International Journal of Modern Physics B

The microstructures and mechanical properties of as-extruded Mg–2.3Zn–0.18Y–$x$Zr ($x$ = 0.03, 0.06 and 0.13 at.%) alloys and aged Mg–2.3Zn–0.18Y–0.13Zr alloy were studied. The results revealed that the microstructures of as-extruded Mg–2.3Zn–0.18Y–$x$Zr alloys are typical bimodal structures. The coarse $\alpha$-Mg grains are surrounded by fine dynamically recrystallized $\alpha$-Mg grains. The average size of $\alpha$-Mg grains decreases with increasing Zr content. Moreover, the addition of Zr (at.%) can improve the mechanical properties of alloy. The as-extruded Mg–2.3Zn–0.18Y–0.13Zr alloy has the best mechanical properties with ultimate tensile strength (UTS) and yield strength (YS) of 346 MPa and 292 MPa, respectively, and an elongation of 26.7%, which can be attributed to the grain refining effect and precipitate strengthening. The UTS and elongation of Mg–2.3Zn–0.18Y–0.13Zr alloy changed slightly after aging treatment, but the YS increases remarkably, with the maximum increase of 30 MPa. The fracture surfaces of all alloys consist of many tearing ridges and dimples.

AZ61 Mg alloy contains Al and Zn, and it has a good combination of castability, strength and ductility. However, the effect of other alloying elements on AZ61 is seldom investigated. Lead is a cheap metallic material, though its vapor is hazardous, a small amount of Pb as an alloying addition will not have significant influence on the application of Mg alloys. Studies showed that the Pb addition suppresses the formation and growth of discontinuous precipitation in AZ91 alloy. In our study, a small amount of Pb element was added into the AZ61 alloy. Mechanical properties of the alloy have been improved. The microstructures were examined by the optical microscopy (OP), scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS). The elemental distribution with Pb alloying was explicitly studied. This alloy composed of $\alpha$-Mg phase and $\beta$-Mg${}_{17}$Al${}_{12}$ phase, while Pb element inclined to distribute in $\alpha$-Mg rather than in $\beta$-Mg${}_{17}$Al${}_{12}$ phase.

The elastoplastic properties of plasma-sprayed Cr₃C₂–NiCr coatings were obtained through the dimension analysis and inverse analysis by combining the experimental nanoindentation tests and numerical modeling. The digital image processing technique was used to extract the pore distribution inside the coatings based on the actual microstructure. Finally, the effect of pore distribution on the coating residual stress during nanoindentation process was analyzed through simulations. The anisotropic pore microstructure shows different mechanical responses and stress propagation behaviors during nanoindentation process. The elastic modulus of the coating demonstrates anisotropy along the spraying direction and the transverse directions due to the presence of pores.

Stainless steel surface was irradiated by linear polarized laser (800 nm, 35 fs, 4 Hz and 0.7 J/cm²) with different pulse numbers. Environmental scanning electron microscope (ESEM/EDS) was used for detailed morphology, microstructure and composition studies. The wettability of irradiated steel surface was tested by Interface Tensiometer JC-2000X and compared with untreated stainless steel. Results showed that micro/nanostripes with different periods were formed. The period increased with the increasing pulse numbers from 450 nm for 90 pulses to 500 nm for 180 pulses. The orientation of those stripes was parallel with the laser beam polarization. Nanoparticles were observed on those periodic structures. EDS indicated that the atomic ratio of Cr increased and the atomic ratios of Fe and Ni decreased after laser irradiation, which may enhance the corrosion resistance due to the Cr-rich layer. The prepared structure exhibited hydrophobic property without further treatment. The formation mechanism of micro/nanoperiodic structures was also explored.

The exfoliation corrosion (EXCO) sensitivities and electrochemical corrosions of A7N01 aluminum (Al) alloys with 0.074% and 0.136% Cu contents were investigated in EXCO solution. The exfoliation corrosion developed more rapidly for the alloy with 0.136% Cu by expressing higher exfoliation rate and deeper corrosion pits as observed by SEM and laser confocal scanning microscopy (LCSM). In EXCO solution, the alloy with 0.136% Cu content showed lower open-circuit potential (OCP) than the alloy with 0.074% Cu content. The alloy with 0.136% Cu content had bigger “hysteresis loop” in cyclic polarization curve which meant lower self-passivation ability. In electrochemical impedance spectroscopy plot, its curvature radius and capacitance index were lower. The electrochemical test results revealed that the alloy with 0.136% Cu content showed more severe electrochemical corrosion than the alloy with 0.074% Cu content, consistent with the exfoliation corrosion results. The microstructures of two alloys were observed through optical microscopy (OM) and transmission electron microscopy (TEM). The continuous distribution of the equilibrium precipitate $\eta$-MgZn₂ on grain boundaries, the decreasing of the width of precipitate-free zone (PFZ) and the coarse Cu–Fe–Si–rich phase were responsible for the higher corrosion sensitivity of the Al alloy with 0.136% Cu than that of Al alloy with 0.074% Cu content in EXCO solution.

The solidification and precipitation behaviors of AE42 magnesium at different quenching temperatures were studied. The results showed that the liquid–solid transition temperature range of AE42 alloy was from 630${}^{\circ }$C to 590${}^{\circ }$C. Precipitation of two kinds of rare earth compounds during solidification had been found. One was Al₂RE phase at 616${}^{\circ }$C. The other was Al${}_{11}$RE₃ phase at 604${}^{\circ }$C. The solidification path of AE42 alloy was L $\to$ $\alpha$-Mg $\to$ $\alpha$-Mg+Al₂RE $\to$ Al₂RE+$\alpha$-Mg+Al${}_{11}$RE₃.

The structural properties, formation heats, cohesive energies, elastic properties and electronic structures of common intermetallics in CrMnFeCoNiZr system high-entropy alloys are analyzed by using density functional theory. The calculation results show that Co₁Zr₁, Co₂Zr₁, Fe₂Zr₁ and Fe${}_{23}$Zr₆ phases may form in the casting process of the alloy, which indicates good agreement with the XRD results of the self-designed alloys. The calculated elastic constants reveal that Co₂Zr₁, Fe₂Zr₁ and Fe${}_{23}$Zr₆ are mechanically stable. In addition, the results show that Co₂Zr₁, Fe₂Zr₁ and Fe${}_{23}$Zr₆ with high shear modulus and elastic modulus would be excellent strengthening phases in high-entropy alloy and would improve the hardness of the alloys.

This paper analyzes two failure cases of creep-caused fracture of PbSn solder joint, including the joint between the wire and solder cup in the connector and the joint between the integrated circuit (IC) pins and the printed circuit board (PCB). The environment conditions, for the creep of PbSn solder joint is demonstrated, including the temperature and stress level. The stress origin and fracture morphology are summarized based on the failure analysis. Besides, the developing process of creep-caused fracture is explained. The paper comprehensively clarifies the creep mechanism of PbSn solder and consequently provides significant guidance for the reliable electronic assembly to avoid the creep-caused damage.

A modified single-edge notch tension (SENT) specimen exposed to saline environment was utilized to investigate the corrosion–fatigue crack growth behaviors of 5083, 6005 and 7N01 aluminum alloys. The fatigue crack propagation life, corrosion–fatigue crack rate ($da/dN$) were tested. The microstructures and fracture surfaces of specimens were examined by optical microscopy and scanning electron microscopy (SEM). The results showed that fatigue crack propagation rate of 7N01 in 3.5% NaCl was significantly higher than 6005 and 5083 alloys. The mechanisms of anodic dissolution and hydrogen embrittlement are used to explain the results.

Developing amorphous alloys with good corrosion resistance has attracted wide interests recently. In this work, a series of Fe${}_{73.5-x}$Ni${}_x$Cu₁Nb₃Si${}_{13.5}$B₉ ($x=0$, 1, 2, 3 and 4 at.%) amorphous alloys are fabricated. The influence of Ni addition on the structure and corrosion resistance of the alloys in KNO₃ solution was investigated. The amorphous ribbons showed excellent corrosion resistance due to the formation of a stable passive film that ensured a very large passivation plateau. The corrosion resistance is sensitive to the minor addition of Ni ($\le$4 at.%), which significantly improved the corrosion resistance according to the results of electrochemical measurements.

The Fe–6.5% Si/SiO₂ powder cores were prepared by dry-type stirring ball milling and subsequent spark plasma sintering (SPS). Microstructure, magnetic properties and sintering mechanism of Fe–6.5% Si/SiO₂ powder core were investigated. The experimental result indicated that Fe–6.5% Si particles were perfectly surrounded by SiO₂ insulating layer with cristobalite structure. Compared with Fe–6.5% Si powder core, Fe–6.5% Si/SiO₂ powder core has 20 times higher electrical resistivity ($1.7\times 10^{-5}\mathrm{\Omega }\cdot \mathrm{\text{m}}$) and maintained excellent soft magnetic properties ($M_s=183.7$ emu/g, $H_c=7.8$ Oe). Core losses decreased to nearly 1/10 of those of Fe–6.5% Si powder core due to the insulation effect of SiO₂ particles. Sintering mechanisms of Fe–6.5% Si/SiO₂ core-shell powders during spark plasma sintering are proposed on the basis of high electrical resistivity (easy to heat) and pin effects (easy to discharge) of SiO₂ particles.

Zr-based amorphous alloys are promising materials applied in engineering field, due to their strong glass-forming ability, outstanding mechanical properties and relatively low cost. In this work, the crystallization kinetics of Zr${}_{56}$Co${}_{18-x}$Ni${}_x$Al${}_{16}$ ($x=0$, 2, 4 and 8; marked as Ni0, Ni2, Ni4 and Ni8, respectively) alloys are investigated in detail. The results show that, due to the addition of Ni, the glass transition of the alloys presents obvious dynamic characteristics, i.e., with the increasing heating rate, all characteristic temperatures are shifted to higher temperature. By fitting the Kissinger equation, the glass transition activation energy of Ni8 is the highest, indicating that Ni8 is much more difficult to crystallize. Therefore, the Ni8 alloy has the strongest anti-crystallization ability in the Zr${}_{56}$Co${}_{18-x}$Ni${}_x$Al${}_{16}$ alloys investigated.

Fe–6.5 wt.% Si powder coated with 10 wt.% MnZn(Fe₂O₄)₂ (MnZn ferrite) was successfully prepared by using dry-type stirring ball milling. The Fe–6.5 wt.% Si/MnZn(Fe₂O₄)₂ soft magnetic composites were prepared by subsequent spark plasma sintering. This paper aims at analyzing the microstructure and magnetic properties of Fe–6.5 wt.% Si/MnZn(Fe₂O₄)₂ soft magnetic composites (sintering temperature: 750${}^{\circ }$C, sintering pressure: 50 MPa, holding time: 8 min, heating rate: 60 K/min). Based on X-ray diffraction and scanning electron microscopy, microstructure and powder morphology were examined and magnetic measurements on bulk samples were conducted by vibrating sample magnetometer and impedance analyzer. According to the experiments results, Fe–6.5 wt.% Si/MnZn(Fe₂O₄)₂ composites displayed a core-shell structure, and ceramic phase was observed after sintering. The Fe–6.5 wt.% Si/MnZn(Fe₂O₄)₂ composites achieved high resistivity ($\rho :2.9$ m$\mathrm{\Omega }$/cm) while maintaining excellent magnetic properties ($M_s:174.00$ emu/g). Core losses especially at medium and high frequencies were significantly reduced.

Tensile deformation behavior of ultrafine-grained (UFG) copper processed by accumulative roll-bonding (ARB) was studied under different strain rates at room temperature. It was found that the UFG copper under the strain rate of 10${}^{-2}$ s${}^{-1}$ led to a higher strength (higher flow stress level), flow stability (higher stress hardening rate) and fracture elongation. In the fracture surface of the sample appeared a large number of cleavage steps under the strain rate of 10${}^{-3}$ s${}^{-1}$, indicating a typical brittle fracture mode. When the strain rate is 10${}^{-2}$ or 10${}^{-1}$ s${}^{-1}$, a great amount of dimples with few cleavage steps were observed, showing a transition from brittle to plastic deformation with increasing strain rate.

Selective laser melting (SLM) was used to prepare 316L stainless steel parts and the effects of laser power on the microstructure and mechanical properties of the final products were studied. With increasing applied laser power, the defects of as-built parts were reduced greatly and the as-built parts presented a highest relative density of 99.1%. The tensile strength of samples was significantly improved from 321 ± 10 MPa to 722 ± 10 MPa. The microhardness was homogeneous; the residual stresses in the samples were tensile, which were higher in the section perpendicular to the laser scanning strategy. The probable reasons for this phenomenon were proposed.

Additive manufacturing technology is a systematic process based on discrete-accumulation principle, which is derived by the dimension of parts. Aiming at the dimension mathematical model and slicing problems in additive manufacturing process, the constitutive relations between micro-beam plasma welding parameters and the dimension of part were investigated. The slicing algorithm and slicing were also studied based on the dimension characteristics. By using the direct slicing algorithm according to the geometric characteristics of model, a hollow thin-wall spherical part was fabricated by 3D additive manufacturing technology using micro-beam plasma.

Numerical simulation and intelligent optimization technology were adopted for rolling and extrusion of zincked sheet. By response surface methodology (RSM), genetic algorithm (GA) and data processing technology, an efficient optimization of process parameters for rolling of zincked sheet was investigated. The influence trend of roller gap, rolling speed and friction factor effects on reduction rate and plate shortening rate were analyzed firstly. Then a predictive response surface model for comprehensive quality index of part was created using RSM. Simulated and predicted values were compared. Through genetic algorithm method, the optimal process parameters for the forming of rolling were solved. They were verified and the optimum process parameters of rolling were obtained. It is feasible and effective.

Direct writing technique is usually used in femtosecond laser two-photon micromachining. The size of the scanning step is an important factor affecting the surface quality and machining efficiency of micro devices. According to the mechanism of two-photon polymerization, combining the distribution function of light intensity and the free radical concentration theory, we establish the mathematical model of coverage of solidification unit, then analyze the effect of coverage on the machining quality and efficiency. Using the principle of exposure equivalence, we also obtained the analytic expressions of the relationship among the surface quality characteristic parameters of microdevices and the scanning step, and carried out the numerical simulation and experiment. The results show that the scanning step has little influence on the surface quality of the line when it is much smaller than the size of the solidification unit. However, with increasing scanning step, the smoothness of line surface is reduced rapidly, and the surface quality becomes much worse.

Aluminum (Al)-based materials composited of different low melting point materials were prepared by mechanical ball-milling. Hydrogen production using these materials was investigated to help resolving the safety issues associated with the storage and transportation of hydrogen. The phase composition and microstructure of the Al-based composited materials were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. As observed in this study, the addition of low melting point metals (such as Sn, Bi and In) helped to lower the initial Al-water reaction temperature and to increase the yield in the production of hydrogen. Samples of optimized compositions, Al–6% Sn–4% Bi and Al–6% Sn–4% In, were found to exhibit high hydrogen production yields of up to 448 and 515 mL, respectively. Meanwhile, their hydrogen generation rates were increased.

Bending fretting fatigue behavior of 17CrNiMo6 alloy structural steel at room temperature was investigated under different bending and contact loads; and the $S$–$N$ curve also was built up. The results showed that the $S$–$N$ curve had a “C” shape. The bending fretting fatigue life was mainly dependent on the bending fatigue stress and fretting displacement. The limit of the specimens and the fretting fatigue life were dramatically decreased by fretting actions. The bending fretting fatigue damage changed under varied bending fatigue stress levels. When the wear first occurred, there is a lower bending fatigue stress; and with a higher bending fatigue load, microcracks were generated. However, some serious wear and surface delamination were observed under the highest fatigue load.

The modeling and numerical method for the dynamics of a planar-motion rigid body with frictional contact between plane surfaces were presented based on the theory of contact mechanics and the algorithm of linear complementarity problem (LCP). The Coulomb’s dry friction model is adopted as the friction law, and the normal contact forces are expressed as functions of the local deformations and their speeds in contact bodies. The dynamic equations of the rigid body are obtained by the Lagrange equation. The transition problem of stick-slip motions between contact surfaces is formulated and solved as LCP through establishing the complementary conditions of the friction law. Finally, a numerical example is presented as an example to show the application.

During the manufacturing of tires, surface pollutants on tire mould will lead to the production of unqualified tires. Tire moulds need to be regularly cleaned. Laser cleaning is recognized as a non-destructive, effective, precise and environmental friendly method. In this paper, laser cleaning was used to remove contaminants on tire mould surface. First, laser induced damage experiments were performed. The results showed that the roughness and hardness of the cast steel sample surface seldom changed under the energy range of 140.1–580.2 mJ laser irradiation 1 pulse and the energy range of 44.7–168.9 mJ laser irradiation 100 pulses. In the laser cleaning experiments, the cleaning thresholds and the optimal cleaning parameters were obtained. Results indicated that laser cleaning was safe and effective for tire mould contamination removal.

Ni–Co–ZrO₂ nanocomposite coatings have been electroplated on mild steel by adding ZrO₂ nanoparticles into an Ni–Co plating solution. The microstructure and mechanical properties of nanocomposite coatings were systematically investigated. The results show that the microhardness of Ni–Co–ZrO₂ nanocomposite coatings varied significantly with the quantity of ZrO₂ nanoparticles. Ni–Co–10 g/L ZrO₂ nanocomposite coating exhibited the optimum mechanical properties due to the dispersion strengthening effect. Addition of ZrO₂ nanoparticles beyond 10 g/L led to particle agglomeration and caused a porous coating structure, resulting in a deterioration of coating mechanical properties.

Black nickel coatings are widely used in industries due to their shiny black color and other unique properties. However these coatings are normally soft, which limits their applications. In order to increase the mechanical properties of black nickel coatings, sol-enhanced technology has been applied to the plating process. TiO₂ sol-enhanced black nickel nanocomposite coatings were electroplated on nickel-coated brass. A systematic study on the microstructure and properties of the black coatings were conducted. The effects of TiO₂ concentration (TiO₂ sol concentration in 0–20 mL/L) on the surface morphology, nanohardness and wear resistance have been studied. The results indicated that the nanohardness of the sol-enhanced black nickel coating was increased by $\sim$20%. The mechanisms of improvement and surface morphology variation were also discussed.

Two types of WC–12Co coatings with different modifications were deposited on steel substrates using high velocity oxygen fuel (HVOF) spraying. The coated samples were oxidized at 550${}^{\circ }$C and 650${}^{\circ }$C in ambient atmosphere. Oxidation mass gain was measured by electronic balance. Phase composition and microstructure evolution of both coatings after oxidation were conducted by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Microhardness testing was performed before and after oxidation testing. The results showed that at 550${}^{\circ }$C and 650${}^{\circ }$C, the rare-earth modified WC–12Co coating has lower oxidation rates compared with the nanostructured WC–12Co coating. This might be due to the rare-earth modification coating reducing the porosity and oxygen diffusion in the coatings, therefore delaying the crack formation and propagation.

Sn coatings were widely used in electronic and device industries due to their unique properties. Sn–TiO₂ sol-enhanced nanocomposite coatings were prepared in order to improve the mechanical properties of Sn coatings. The microstructure, mechanical properties and conductivity of sol-enhanced Sn–TiO₂ nanocomposite coatings were systematically investigated. The results show that after adding an optimum quantity of TiO₂ nanoparticles, the nanohardness of Sn–TiO₂ coatings was increased by 75% while the conductivity remained unaltered when compared with a pure Sn coating. The effect of TiO₂ sol addition on the properties of coatings was discussed.

Under the sodium aluminates’ system, microarc oxidation treatment was conducted on the superhard aluminum alloy 7A04 for different times. The microstructure of microarc oxidation ceramic layer was investigated by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The influences of different oxidation times on the adhesion strength of ceramic layer and substrate, the morphology of surface and cross-section, the phase composition and the electrochemical properties were studied. The results indicated that the connection of the coating and substrate appears to be metallurgical bonding and dense ceramic layer, and the surface is in a “volcanic vent” morphology, which is composed of $\gamma$-Al₂O₃ and little $\alpha$-Al₂O₃. The corrosion resistance of ceramic layer is improved significantly in contrast with that of the substrate.

The Al5056/SiC composite coatings were prepared by cold spraying. Experimental results show that the SiC content in the composite coating deposited with the SiC powder having an average size of 67 $\mu$m (Al5056/SiC-67) is similar to that deposited with the SiC powder having an average size of 27 $\mu$m (Al5056/SiC-27). The microhardness and cohesion strength of Al5056/SiC-67 coating are higher than those of the Al5056/SiC-27 coating. In addition, the Al5056/SiC-67 coating having a superior wear resistance because of the coarse SiC powder with a superior kinetic energy contributes to the deformation resistance of the matrix Al5056 particles.

Gold (Au) coatings are widely used for electrical contacts in devices, decoration and jewelry. However, the relatively low hardness and poor wear resistance of pure Au coatings lead to a short service life and limit their application. Ni is frequently used as an alloying element to enhance the hardness but it lowers the conductivity of Au coatings. In this research, Co was co-deposited as an alloying element with Au to improve its mechanical properties while maintaining conductivity. TiO₂ sol in different concentrations was added to the Au–Co plating bath to further enhance the coating strength. Systematic studies including surface morphology, hardness, wear resistance and electrical conductivity have been carried out. Key results from nanoindentation tests demonstrated that the hardness of Au–Co–TiO₂ composite coating was increased by 30% when compared to a pure Au–Co coating, while the electrical conductivity has been kept at the same level.

Anodized aluminum (Al) and Al alloys have a wide range of applications. However, certain anodized finishings have relatively low hardness, dull appearance and/or poor corrosion resistance, which limited their applications. In this research, Al was first electropolished in a phosphoric acid-based solution, then anodized in a sulfuric acid-based solution under controlled processing parameters. The anodized specimen was then sealed by two-step sealing method. A systematic study including microstructure, surface morphology, hardness and corrosion resistance of these anodized films has been conducted. Results show that the hardness of this new anodized film was increased by a factor of 10 compared with the pure Al metal. Salt spray corrosion testing also demonstrated the greatly improved corrosion resistance. Unlike the traditional hard anodized Al which presents a dull-colored surface, this newly developed anodized Al alloy possesses a very bright and shiny surface with good hardness and corrosion resistance.

Tungsten as the most effective carbide-forming element was added in the Fe–Cr13–C hardfacing alloy to precipitate WC particles. Optical microscope (OM), scanning electron microscope (SEM) and energy-dispersive spectrometer (EDS) were used to investigate the microstructures of the hardfacing alloy. The wear resistance was tested through a slurry rubber wheel abrasion test machine, and the wear behavior was also studied. The results indicate that the microstructures of the hardfacing alloy consist of lath martensite, residual austenite and WC particles. The wear resistance can be significantly improved through the addition of tungsten element being provided by the precipitation of WC particles. And the predominant wear mechanism was microcutting with shallow grooves and spalling.

The Ni–Cr–Fe metal powder was deposited on EA4T steel by laser cladding technology. The microstructure and chemical composition of the cladding layer were analyzed by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The bonding ability between the cladding layer and the matrix was measured. The results showed that the bonding between the cladding layer and the EA4T steel was metallurgical bonding. The microstructure of cladding layer was composed of planar crystals, columnar crystals and dendrite, which consisted of Cr₂Ni₃, $\gamma$ phase, M${}_{23}$C₆ and Ni₃B phases. When the powder feeding speed reached 4 g/min, the upper bainite occurred in the heat affected zone (HAZ). Moreover, the tensile strength of the joint increased, while the yield strength and the ductility decreased.

Chromium nitride coatings were prepared by reactive DC-superimposed high-power-impulse magnetron sputtering (HiPIMS) system. The influence of substrate bias on the microstructure and mechanical properties of CrN coatings was investigated. XRD and cross-sectional SEM were utilized to characterize the film structures. Mechanical properties were characterized by nanoindentation and Vickers indentation test. The results revealed that the microstructure and mechanical properties of CrN coatings were affected by bias voltage. The CrN coatings exhibited dense and fine columnar grain structure with the hardness of about 18.7 GPa. The fracture toughness of CrN coatings was around 3.16 MPa ⋅ m${}^{1/2}$. However, further increase of the bias voltage from −250 V to −300 V led to the degradation of coating properties.

Cr₂O₃–TiO₂ coatings with different proportions of La₂O₃ were deposited by atmospheric plasma spraying. The coatings were evaluated by hardness tester, surface roughness tester, SEM and wear tester. The experiment results showed that the addition of La₂O₃ could improve the microhardness and decrease porosity, wear rate and surface roughness of the coating. The coating containing 2 wt.% La₂O₃ had the best tribological properties. The dominant wear mechanism is a mixture of abrasive wear and adhesive wear. The microscopic analysis suggests that the addition of La₂O₃ could refine the microstructure and promote the formation of solid solution powder, and then affect the properties of coatings.

Through investigating the corrosion fatigue crack initiation behavior of A7N01P-T4 aluminum alloy welded joints in 3.5 wt.% NaCl solution, corrosion fatigue crack initiation life is formulated as $N_i=6.97\times 10^{12}{[\mathrm{\Delta }{\sigma }_{\mathrm{\text{eqv}}}^{1.739}-{49}^{1.739}]}^{-2}$ and the mechanism of corrosion fatigue crack initiation is proposed. SEM and TEM tests revealed that several corrosion fatigue cracks formed asynchronously and the first crack does not necessarily develop into the leading crack. The uneven reticular dislocations produced by fatigue loading are prone to piling up and tangling near the grain boundaries or the second phases and form the “high dislocation-density region” (HDDR), which acts as an anode in microbatteries and dissolved to form small crack. Thus the etching pits, HDDR near the grain boundaries and second phases are confirmed as the main causes inducing the initiation of fatigue crack.

Butt joining of AA6061 aluminum (Al) alloy and 304 stainless steel of 2-mm thickness was conducted using laser–MIG hybrid welding–brazing method with ER4043 filler metal. To promote the mechanical properties of the welding–brazing joints, two kinds of intermediate layers (Al–Si–Mg alloy and Ag-based alloy) are used to adjust the microstructures of the joints. The brazing interface and the tensile strength of the joints were characterized. The results showed that the brazing interface between Al alloy and stainless steel consisted of double layers of Fe₂Al₅ (near stainless steel) and Fe₄Al${}_{13}$ intermetallic compounds (IMCs) with a total thickness of 3.7 $\mu$m, when using Al–Si–Mg alloy as the intermediate layer. The brazing interface of the joints using Ag-based alloy as intermediate layer also consists of double IMC layers, but the first layer near stainless steel was FeAl₂ and the total thickness of these two IMC layers decreased to 3.1 $\mu$m. The tensile strength of the joints using Al–Si–Mg alloy as the intermediate layer was promoted to 149 MPa, which was 63 MPa higher than that of the joints using Al–Si–Mg alloy as the intermediate layer. The fractures occurred in the brazing interface between Al alloy and stainless steel.

Aluminum alloy has been widely used in automobiles, high-speed trains, aerospace and many other fields. The loss of elements during welding process causes welding defects and affects the microstructure and properties of the joints. This paper discusses the correlation between welding process, spectral intensity and loss of elements in laser-arc hybrid welding of Al alloys. The results show that laser power and arc current have a significant impact on the spectral intensity and loss of elements. Compared with the base metal, the contents of alloying elements in the weld area are lower. The burning losses of alloy elements increase with the welding heat input.

Two dissimilar Al alloys, 5083-H111 and 6005A-T6, were joined by hybrid laser–MIG welding method. Mechanical properties of the welded joint were investigated and compared. The results show that the tensile strength of the dissimilar joint is 219.8 MPa, 11.7% higher than that of 6005A-T5 joint. After statistical analysis of the fatigue data, the $P$–$S$–$N$ curves of the dissimilar joint were obtained. The mean fatigue strength at $N_f=10^7$ of the dissimilar joint is 112.5 MPa. The fatigue strength at $N_f=10^7$ of the dissimilar joint for a given 10% probability of failure, at a confidence level of 95%, is 101.4 MPa. The fatigue strength at $N_f=10^7$ of the dissimilar joint is almost same as that of the 6005A-T6 joint. In welded structure designing, different $P$–$S$–$N$ curves should be chosen according to the different service conditions and reliability requirements.

Simulated HAZ continuous cooling transformation (SH-CCT) diagram presents the start and end points of phase transformation and the relationships of the microstructures of HAZ, temperature and cooling rates. It is often used to assess the weldability of materials. In this paper, a weathering steel Q345C which is widely used in the bogies manufacturing was studied. The cooling times from 800${}^{\circ }$C to 500${}^{\circ }$C ($t_{8/5}$) were from 3 s to 6000 s, aiming to study the microstructures under different cooling rates. Different methods such as color metallography were used to obtain the metallography images. The results show that ferrite nucleates preferentially at the prior austenite grain boundaries and grows along the grain boundaries with a lath-like distribution when $t_{8/5}$ is 300 s. Austenite transforms into ferrite, pearlite and bainite with decreasing $t_{8/5}$. Pearlite disappears completely when $t_{8/5}=150$ s. Martensite gradually appears when $t_{8/5}$ decreases to 30 s. The hardness increases with decreasing $t_{8/5}$. The SH-CCT diagram indicates that the welding input and $t_{8/5}$ should be taken into consideration when welding. This work provides the relationships of welding parameters and microstructures.

Weld joint softening occurs during the welding process of heat-treatable aluminum alloys and strongly influences the mechanical properties. In this work, the softening of heat-treated Al–Zn–Mg alloy was studied in the multipass welding process. By Gleeble-3500 thermal–mechanical simulator, the heat treatment and tensile test with welding thermal cycles were carried out to simulate the microstructure evolution and mechanical softening during multipass welding. After that, the softening mechanism of the HAZ was analyzed by microstructure analysis. The results indicate that the heat-treated Al–Zn–Mg alloy exhibited obvious softening after several thermal cycles with peak temperature higher than 200${}^{\circ }$C, and this phenomenon is worse with increasing peak temperature. Based on the microstructure analysis, it was found that the reinforcement phase changes according to the applied thermal cycles, which strongly affects the strength of Al–Zn–Mg alloys.

Aluminum alloy 5083 was joined with Sn–$x$Zn ($x=0$, 5, 9, 30 and 60 wt.%) filler metal by ultrasonic soldering at 400${}^{\circ }$C. The joint microstructure consisted of $\beta$-Sn and $\alpha$-Al solid–solution phases when using pure Sn solder. Zn-rich phases were observed in the joints with Sn–Zn filler metal. The Zn-rich phases grew thicker and larger with the increase in Zn content in the filler metal. The joints soldered with Sn–30Zn filler metal reached a maximum shear strength of 70 MPa. Joint cracking occurred at the interface of pure Sn and Sn–9Zn solders as indicated by SEM observation of the fracture surfaces. The locations of the fracture surface moved from the interface to the seam when using the Sn–30Zn or Sn–60Zn filler metal. The coarse Zn-rich phases were also observed on the fracture surface using Sn–60Sn solder, which results in a shear strength reduction of the joints.

In this paper, welded joints of four types of A7N01S-T5 aluminum alloy with different chemical compositions were investigated. The welding process was under 70% environmental humidity conditions at 10${}^{\circ }$C with single-pulse GMAW welding technology. The strength and fracture toughness of the four types of samples were tested, and the microstructures were investigated by micro-X-ray fluorescence (SR-LXRF) technology and backscattered electron diffraction (EBSD) technology. The results showed that the #2 alloy that is composed of Zn: 4.59 wt.%, Mg: 1.56 wt.% Mn: 0.22 wt.%, Cr: 0.14 wt.%, Zr: 0.01 wt.% and Ti: 0.027 wt.% had the best combination of tensile strength and elongation, with the values of 302.35 MPa and 3.74%, respectively. The better result for the combination of the strength and elongation was mainly determined by the volume fraction and size. The fine grain size and compositions played important roles to obtain high fracture toughness.

With the promotion of fuel economy policy and automobile lightweight concept, ferritic stainless steels applied in vehicles’ exhaust hot end systems have been developed. This paper simulated the high-temperature environment at which the automobile exhaust system serviced in for high-temperature corrosion. Kinetic curves were conducted in isothermal environments at 1000${}^{\circ }$C. X-ray diffraction, scanning electron microscope and energy dispersive spectrometer were used to study the oxidation behavior of ferritic stainless steels and the effects of tungsten (W) addition. The results show that, with increasing oxidation time, the rate of weight gains increase and the main failure is spalling of surface oxide layer. The addition of W has a complicated effect on the oxidation behavior of ferritic stainless steel weldment.

Direct current A-TIG (DCEN A-TIG) welding using special active agent had eliminated the pores and the oxidation of 2219 high-strength aluminum alloy in welding. Addition of AlF₃–25% LiF active agent to DCEN A-TIG welding and arc morphology showed a trailing phenomenon. However, the change in arc morphology was not remarkable when AlF₃–75% LiF active agent was added. Addition of AlF₃–75% LiF active agent can refine the grain size of DCEN A-TIG joint. The mechanical properties of the weld were optimal at 10% AlF₃–75% LiF active agent. Compared with AC TIG and AC A-TIG welding, DCEN A-TIG welding yielded better results for 2219 Al alloy.

Single-wire flux-aided backing-submerged arc welding (FAB-SAW) technology has been widely used to weld thick steel plate due to its easy assembly and high heat input. The microstructure and property of welded joint are closely related to the thermal field of FAB-SAW process. In this research, the feature of thermal field for single-wire FAB-SAW was investigated. Based on the heat transfer mechanism, a three-dimensional transient model for thermal field was developed based on the influence of steel thickness, groove angle and ceramic backing. The temperature profile in single-wire FAB-SAW of D36 steel under different welding conditions was simulated by ANSYS. The characteristic of thermal field was analyzed and the influences of groove angle on temperature field for different plate thicknesses were discussed. The calculated geometries and dimensions of weld cross-section under different conditions show a good agreement with the experimental results. This newly built model can describe the thermal field accurately, which would be helpful to understanding the thermophysical mechanism of FAB-SAW and optimizing the welding process.

Welded joints made of 6061-T6 Al alloy were studied to evaluate warm laser shock peening (WLSP) and laser shock peening (LSP) processes. The estimation model of laser-induced surface residual stress was examined by means of experiments and numerical analysis. The high-cycle fatigue lives of welded joint specimens treated with WLSP and LSP were estimated by conducting tensile fatigue tests. The fatigue fracture mechanisms of these specimens are studied by surface integrity and fracture surface tests. Experimental results and analysis indicated that the fatigue life of the specimens processed by WLSP was higher than that with LSP. The large increase in fatigue life appeared to be the result of the larger residual stress, more uniform microstructure refinement and the lower surface roughness of the WLSP specimens.

Flux-aided backing-submerged arc welding has been conducted on D36 steel with thickness of 20 mm. The effects of processing parameters such as welding current, voltage, welding speed and groove angle on welding quality were investigated by Taguchi method. The optimal welding parameters were predicted and the individual importance of each parameter on welding quality was evaluated by examining the signal-to-noise ratio and analysis of variance (ANOVA) results. The importance order of the welding parameters for the welding quality of weld bead was: welding current $>$ welding speed $>$ groove angle $>$ welding voltage. The welding quality of weld bead increased gradually with increasing welding current and welding speed and decreasing groove angle. The optimum values of the welding current, welding speed, groove angle and welding voltage were found to be 1050 A, 27 cm/min, 40${}^{\circ }$ and 34 V, respectively.

Stress concentration is a key factor that affects the fatigue strength of welded joints. In this study, the fatigue strengths of butt joints with and without the weld reinforcement were tested to quantify the effect of stress concentration. The fatigue strength of the welded joints was measured with a high-frequency fatigue machine. The $P$–$S$–$N$ curves were drawn under different confidence levels and failure probabilities. The results show that butt joints with the weld reinforcement have much lower fatigue strength than joints without the weld reinforcement. Therefore, stress concentration introduced by the weld reinforcement should be controlled.

The stress corrosion cracking (SCC) behaviors at slow strain rate tensile (SSRT) test of AISI301L stainless steel laser–MIG welded joints in 3.5 wt.% NaCl solution at 20${}^{\circ }$C, 40${}^{\circ }$C and 60${}^{\circ }$C were investigated. The results showed that the weld metal composed of as-cast with $\delta$-Fe and austenite. The base metal (BM) and heat affected zone (HAZ) contained strain-induced M phase. The stress and strain decreased with the increasing temperature. The SCC cracks are initiated by anodic dissolution at 20${}^{\circ }$C. Besides the anodic dissolution mechanism, hydrogen-induced SCC mechanism had appeared in 3.5 wt.% NaCl solution at 40${}^{\circ }$C and 60${}^{\circ }$C.

A two-step anodization method has been used to produce patterned arrays of TiO₂ on the surface of Ti sheet. Hexagonal ripples were created on Ti substrate after removing the TiO₂ layer produced by first-step anodization. The shallow concaves were served as an ideal position for the subsequent step anodization due to their low electrical resistance, resulting in novel hierarchical nanostructures with small pits inside the original ripples. The mechanism of morphology evolution during patterned anodization was studied through changing the anodizing voltages and duration time. This work provides a new idea for controlling nanostructures and thus tailoring the photocatalytic property and wettability of anodic TiO₂.

ZnO nanorods were decorated by Cu nanocrystals via magnetron sputtering to form Cu/ZnO nanocomposite arrays. The crystal structure and morphology of Cu/ZnO nanocomposite arrays were characterized by XRD and SEM. The optical absorbance of Cu/ZnO nanocomposite arrays was measured using a UV-vis spectrophotometer and their potential applications were discussed.

Submicron zinc oxide (ZnO) spheres prepared by a two-stage hydrothermal method were assembled into a layer on a substrate by vertical deposition. Vanadium pentoxide (V₂O₅) was deposited onto the top of ZnO spheres by magnetron sputtering followed by annealing in oxygen atmosphere at 500${}^{\circ }$C for an hour. The microstructures and optical properties of the prepared samples were investigated. The photoluminescence (PL) results indicate that the intensity of PL in the annealed ZnO/V₂O₅ composite microstructures is dramatically improved compared to the constituent V₂O₅ and ZnO spheres. The intensity enhancement of light emission from the ZnO/V₂O₅ composite may be attributed to the special microstructure of ZnO particles and the coupling effect between ZnO and V₂O₅. This transition oxide composite may possibly be developed into a new type of high-efficiency light emitting material.

We propose a novel silicon structure, Hot Electron Emitting Substrate (HEES), which exhibits important effect of repeated tunneling at two different voltage ranges, which we refer to as double tunneling. In ambient atmosphere and room temperature, the $I$–$V$ characteristic of HEES shows two current peaks during voltage sweep from 2 to 15 V. These two peaks are formed by the Fowler–Nordheim (FN) tunneling effect and tunneling diode mechanism, respectively.

Morphology and photophysics of polymers are critical to the performance of organic optoelectronics. In this work, poly(3-thiophene) (P3HT) nanoparticles were successfully fabricated by the miniemulsion and reprecipitation methods. The P3HT nanoparticles demonstrated uniform distribution with the domain size of $\sim$40 nm. The photophysics of P3HT nanoparticles was investigated by absorption and steady-state and time-resolved PL spectroscopy. P3HT nanoparticles showed more ordered and longer conjugation length than pristine P3HT. At the same time, P3HT nanoparticles showed aggregate species which are favorable for interchain charge transfer. The organic/inorganic hybrid photodetectors based on P3HT and TiO₂ nanorods were fabricated. The superior performance of the photodetector based on P3HT nanoparticle and TiO₂ nanorods comes from the efficient charge transfer and large donor/acceptor interface.

SnS thin films with gear-like sheet appearance were successfully prepared by close-spaced vacuum thermal evaporation using SnS powders as a source. The influence of substrate temperature on the surface morphology, chemical composition, crystal structure and optical property of SnS thin films was investigated by scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction and ultraviolet–visible–near infrared spectroscopy. The results revealed that serration architecture appeared obviously in the edge of the SnS sheet and the strongest peak at 2$𝜃$=31.63${}^{\circ }$ was broadened and many shoulder peaks were observed with increasing substrate temperature. The atomic ratio of Sn to S increased from 1:1.08 to 1:1.20, the grain size became slightly smaller and the optical absorption edge had a blueshift in the SnS thin film with decreasing substrate temperature.

ZnS nanoparticles were prepared by hydrothermal method using zinc nitrate [Zn(NO${}_3{)}_2$ ⋅ 6H₂O] and thiourea [SC(NH${}_2{)}_2$] as sources of Zn${}^{2+}$ and S${}^{2-}$ ions and cetyltrimethyl ammonium bromide [CH₃(CH₂)${}_{15}$N${}^{+}$(CH₃)₃ ⋅ Br${}^{-}$; CTAB] as a surface active agent. The structural, surface morphology and optical properties of ZnS nanoparticles as a function of growth temperature were investigated. The studies show that ZnS nanoparticles have high transmittance over 70% in the visible light range of 400–800 nm, and it has a strong green emission band at about 520 nm which originates from the recombination of electrons from the energy level of sulfur vacancies with the holes from the energy level of zinc vacancies. With the increase of the growth temperature, the XRD peak intensity and the size of ZnS nanoparticles increase, while the green emission intensity firstly increases and then decreases.

The electrical transport properties are the key factors to determine the performance of ZnO-based quantum effect device. ZnMgO is a typical material to regulate the band of ZnO. In order to investigate the electrical properties of the interface of ZnO/Zn${}_{0.85}$Mg${}_{0.15}$O films, three kinds of ZnO/Zn${}_{0.85}$Mg${}_{0.15}$O films have been fabricated with different thickness. After comparing the structural and electrical properties of the samples, we found that the independent Zn${}_{0.85}$Mg${}_{0.15}$O hexagonal wurtzite structure (002) peak can be detected in XRD spectra. Hall-effect test data confirmed that the two-dimensional electron gas (2DEG) became lower because of the decrease of thickness of Zn${}_{0.85}$Mg${}_{0.15}$O films, increase of impurity scattering and lattice structure distortion caused by the increase of Mg content.

An ultra-broad working temperature dielectric material, Bi₄Ti${}_x$O${}_{12}$($x$ = 2.96, 2.98, 3.0, 3.02 and 3.04), prepared by a conventional mixed oxide route was investigated which is supposed to replace lead-containing ceramics for its outstanding dielectric properties. Microstructure and dielectric properties of well-sintered samples (at 1040${}^{\circ }$C, 1060${}^{\circ }$C, 1080${}^{\circ }$C, 1100${}^{\circ }$C and 1120${}^{\circ }$C) were studied. X-ray diffraction analysis indicated that the new material was in a single Bi-layered perovskite phase. The dielectric constant and dielectric loss at different frequencies (10, 100 and 1000 kHz) were measured at 1100${}^{\circ }$C. With the increasing frequency, the dielectric constant decreased and the dielectric loss was almost unchanged. While at 100 kHz, there is the highest relative permittivity (${𝜀}_r$) of 2822.8 and the lowest dielectric loss of 0.0040 ($x$ = 2.98), the Curie temperature ($T_c$) is 668.9${}^{\circ }$C. At the frequency of 1 MHz, the highest relative permittivity (${𝜀}_r$) is 1115.8 when Ti content is 3.02, and the Curie temperature is 672.2${}^{\circ }$C. SEM can explain the results of the dielectric spectrum at different Ti content and sintering temperatures. $Z\ast$ plots show that Bi₄Ti₃O${}_{12}$ ceramics are a kind of dielectrics. Since it possesses large dielectric constant, low dielectric loss and stable temperature character, this material shows promising applications for the ultra-broad temperature range components, such as high-temperature multilayer ceramic capacitors and microwave ceramics.

A novel phosphor, K₂MgSiO₄:Eu${}^{3+}$, was synthesized by a solid-state reaction method. The phase formation was checked by X-ray powder diffraction. The photoluminescence excitation, emission spectra, decay curve and CIE coordinates of samples with different Eu${}^{3+}$ ion concentrations were investigated in detail. The excitation spectra show a broad wavelength range of 225–470 nm. The K₂MgSiO₄:Eu${}^{3+}$ phosphors exhibit highly red emission peaking at about 616 nm which is assigned to the ⁵D${}_0\to {}^7$F₂ transition of Eu${}^{3+}$ions under the excitation of near-ultraviolet (NUV) (394 nm) light. The critical quenching concentration of Eu${}^{3+}$ doped in the K₂MgSiO₄: Eu${}^{3+}$ phosphors was about 10 mol.% and the concentration quenching mechanism was dipole–dipole interactions between Eu${}^{3+}$ ions. The results indicate that K₂MgSiO₄:Eu${}^{3+}$ is a potential red phosphor candidate for NUV-pumped white light emitting diodes.

BiVO₄/Bi₂MoO₆ composites have been fabricated via the one-step hydrothermal method. The properties of composites were tailored by altering the V/Mo molar ratios. Photocatalytic activities were evaluated by measuring degradation of RhB under visible-light irradiation. BiVO₄/Bi₂MoO₆ composites with V/Mo molar ratio of 8:1 possessing the optimal photocatalytic performance. The enhanced photocatalytic activity was attributed to the efficient charge carrier separation of composite heterostructures. In addition, the study of adsorption and photocatalytic activity suggested that a moderate amount of adsorption has a positive effect on photocatalytic reaction.

The influence of Nb₂O₅-doped concentration on the positive temperature coefficient of resistance (PTCR) effect, electrical properties and microdefects of (Ba${}_{0.95}$Sr${}_{0.05}$)(TiNb${}_x$)O₃ (BSTN) ceramics were investigated. Firing was conducted at 1350${}^{\circ }$C for 2 h in air. The donor-doped content affected the electrical properties, PTCR effect and formation of the microdefect type of the BSTN samples. The room temperature resistivity of the BSTN specimens first decreased and then increased with increasing donor-doped content in the range of 0.2 mol.% Nb${}^{5+}$ to 0.5 mol.% Nb${}^{5+}$. Moreover, the information on microdefects in BSTN ceramics was demonstrated by coincidence Doppler broadening spectrum. The influence of the defects on the PTCR characteristics of the ceramics was also revealed.

This study investigates the influence of dopant content and firing conditions on electrical properties and positive temperature coefficient of resistance (PTCR) effect of Ba${}_{1.005}$(Ti${}_{1-x}$Nb${}_x)$O₃ (BTN) ceramics sintered at different temperatures from 1070${}^{\circ }$C to 1220${}^{\circ }$C for 2 h in a reducing atmosphere and reoxidized within the temperature range of 600–750${}^{\circ }$C for 0.5–8 h. The results indicate that the room-temperature (RT) resistance of the laminated BTN specimens initially decreased and then increased as a function of the dopant concentration. Moreover, the resistance jump exhibited a contrasting tendency. Furthermore, the RT resistance of the BTN samples rapidly decreased at first and then gradually decreased with increasing sintering temperature. Meanwhile, the resistance jump of the samples increased first and then decreased. In addition, the influence of reoxidation times on the PTCR characteristics of ceramics was investigated.

Dense BaZr${}_{0.8}$Y${}_{0.2}$O${}_{3-\delta }$ (BZY) proton-conducting electrolyte membranes are successfully fabricated on NiO–BaZr${}_{0.1}$Ce${}_{0.7}$Y${}_{0.2}$O${}_{3-\delta }$(NiO–BZCY) using tape casting combined with suspension spraying technique. The NiO–BZCY anode substrates were prepared by the tape-casting method and the BZY electrolyte membranes were prepared on the NiO-BZCY anodes by suspension spraying. The thermal decomposition of the anode green tape prepared by tape casting was investigated by thermogravimetry-differential thermal analysis while the phase structure and the morphology of the anode/electrolyte bi-layers were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). No obvious reaction was found between NiO and BZCY in anode substrates and gas-tight BZY membranes were achieved after co-sintering at 1450${}^{\circ }$C. With Sm${}_{0.5}$Sr${}_{0.5}$CoO${}_{3-\delta }$–Ce${}_{0.8}$Sm${}_{0.2}$O${}_{2-\delta }$(SSC–SDC) as the composite cathode, a maximum power density of 121 mW cm${}^{-2}$ was obtained at 650${}^{\circ }$C for the single cell with 23 $\mu$m thick BZY electrolyte. Resistances of the tested cell were investigated under open circuit conditions at different operating temperatures by impedance spectroscopy.

The quantum ratchet effect means that the directed transport emerges in a quantum system without a net force. The delta-kicked model is a quantum Hamiltonian model for the quantum ratchet effect. This paper investigates the quantum ratchet effect based on a time non-uniform double-kicked model, in which two flashing potentials alternately act on a particle with a homogeneous initial state of zero momentum, while the intervals between adjacent actions are not equal. The evolution equation of the state of the particle is derived from its Schrödinger equation, and the numerical method to solve the evolution equation is pointed out. The results show that quantum resonances can induce the ratchet effect in this time non-uniform double-kicked model under certain conditions; some quantum resonances, which cannot induce the ratchet effect in previous models, can induce the ratchet effect in this model, and the strengths of the ratchet effect in this model are stronger than those in previous models under certain conditions. These results enrich people’s understanding of the delta-kicked model, and provides a new optional scheme to control the quantum transport of cold atoms in experiment.

In order to improve the photoelectric transformation efficiency of thin-film solar cells, one plausible method was to improve the transparent conductive oxides (TCO) material property. In-doped tin oxide (ITO) was an important TCO material which was used as a front contact layer in thin-film solar cell. Using magnetron sputtering deposition technique, we prepared preferential orientation ITO thin films on quartz substrate. XRD and SEM measurements were used to characterize the crystalline structure and morphology of ITO thin films. The key step was adding a ZnO thin film buffer layer before ITO deposition. ZnO thin film buffer layer increases the nucleation center numbers and results in the (222) preferential orientation growth of ITO thin films.

Formamidinium lead iodide (FAPbI₃) is a promising hybrid perovskite material for optoelectronic devices. We synthesized bulk single crystal FAPbI₃ by a rapid solution crystallization method. X-ray diffraction (XRD) was performed to characterize the crystal structure. Temperature-dependent photoluminescence (PL) spectra of the bulk single crystal FAPbI₃ were measured from 10 to 300 K to explain PL recombination mechanism. It shows that near band edge emission blueshifts with the temperature increasing from 10 to 120 K and from 140 K to room temperature, a sudden emission band redshift demonstrates near 140 K because of the phase transition from orthorhombic phase to cubic phase. From the temperature-dependent PL spectra, the temperature coefficients of the bandgap and thermal activation energies of FAPbI₃ perovskite are fitted.

Resonance Raman spectra of Be${}_x$Zn${}_{1-x}$O alloy materials were studied using 325 nm Laser. The research showed that the Raman spectra of Be${}_x$Zn${}_{1-x}$O alloys presents a dual-mode vibration. Compare Be${}_x$Zn${}_{1-x}$O alloy with ZnO single crystal, the A₁ (LO) phonon vibration mode of Be${}_x$Zn${}_{1-x}$O alloy moved to the larger wave number direction. The position of A₁ (LO) phonon vibration modes of Be${}_{0.08}$Zn${}_{0.92}$O and Be${}_{0.12}$Zn${}_{0.88}$O was 580 cm${}^{-1}$ and 582 cm${}^{-1}$, respectively. In addition, the temperature-dependent Raman spectroscopy was employed for Be${}_{0.12}$Zn${}_{0.88}$O, and the phonon mode frequency shift with temperature was studied in detail. Finally, the stability of the polar and nonpolar Be${}_x$Zn${}_{1-x}$O alloy materials was studied using resonance Raman spectroscopy. The results showed that the A₁ (LO) phonon mode frequency of polar Be${}_x$Zn${}_{1-x}$O alloy remained in the same position, while the nonpolar Be${}_x$Zn${}_{1-x}$O alloys moved nearly 3.5 cm${}^{-1}$ to larger direction after being placed in the air for two years. The reason may be that the stability of the nonpolar Be${}_x$Zn${}_{1-x}$O alloy is relatively poor upon interaction with molecule such as H₂O, O₂ in the air.

The Y₃Al₅O${}_{12}$ (YAG):Ce ceramic rods and single crystals were prepared by solid state reaction and optical floating zone method, respectively. The XRD results showed that the phases in the YAG:Ce ceramics are mixture of YAG phase and YAlO₃ (YAP) phase. There is only a single YAG phase in the single crystals of YAG:Ce. The mean positron lifetime of the YAG:Ce crystal decreases with increasing Ce content, and reaches minimum at 1 at.% Ce, then increases with Ce content. The mean positron lifetime of the YAG:Ce crystal is higher than that of YAG:Ce ceramic with the same chemical composition. The UV–visible absorption spectra of the YAG:Ce crystals indicated that the transmittances of the YAG:Ce crystals are higher than 90% in the wavelength range from 550 nm to 800 nm. The photoluminescence spectra of the YAG:Ce crystals showed wide luminescence emission peaks located in the range of 525–529 nm. A relatively high luminescence intensity is found in the YAG:Ce crystal with 1 at.% Ce. With further increase of Ce content, the luminescence decreases due to the fluorescence quenching effect.

Thin films of TiO₂-doped ZnO (TZO) with TiO₂ contents from 0.5 to 3.0 wt.% were deposited on glass substrates by RF magnetron sputtering. The microstructures and optoelectronic properties of the TZO films were characterized by XRD, Hall effect analyzer, UV–VIS spectrophotometry and physical property measurement (PPMS-9). Results indicate that the microstructure and optoelectronic properties of TZO films are strongly affected by the TiO₂ content. The best optoelectronic properties were obtained with the film having 2.0 wt.% TiO₂. This film had superior crystal properties, high average optical transmittance (89.0%), and the lowest resistivity (9.58 × 10${}^{-4}$ $\mathrm{\Omega }$ ⋅ cm). Furthermore, the resistivity of this film changed with temperature between 10 and 350 K, they experienced an initial decrease followed by an increase as the temperature increased.

The single crystals of YAG, Cr:YAG and (Cr,Ca):YAG were grown in an optical floating zone furnace. The experimental results show that the optical bandgap of the YAG, (Cr,Ca):YAG and Cr:YAG crystals is about 6.52, 6.31 and 5.50 eV, respectively. The optical bandgap of the (Cr,Ca):YAG crystal is smaller than YAG and larger than Cr:YAG. First-principles calculation results showed that the additions of Cr into YAG will give rise to the change of the electronic states. In a Cr:YAG crystal, the Cr${}^{3+}$ impurity introduces a band of 3$d$ occupied state near the Fermi level, which significantly narrowed the bandgap of Cr:YAG. In a (Cr,Ca):YAG crystal, as the Ca${}^{2+}$ ions substitute for the Y${}^{3+}$ ions, some of the Cr${}^{3+}$ ions will change into Cr${}^{4+}$ ions due to the charge balance, which increased the bandgap of the (Cr,Ca):YAG crystal in comparison with that of the Cr:YAG crystal. The calculation is in agreement with the experimental results.

The Y${}_{2.94}$Dy${}_{0.06}$Al₅O${}_{12}$ (Dy:YAG) ceramic rods were sintered at different temperatures from 1000${}^{\circ }$C to 1450${}^{\circ }$C by solid-state reaction method and the Dy:YAG single crystals were grown by the optical floating zone method. The XRD found the Y₄Al₂O₉ (YAM) phase after sintering at 1000${}^{\circ }$C and disappeared after sintering at 1450${}^{\circ }$C. The YAG phase and the YAlO₃ (YAP) phase were found in the ceramic sintered at $>$1200${}^{\circ }$C. As the sintering temperature increases, the amount of the YAG phase increases, while YAP phase decreases. There is only a single YAG phase in the Dy:YAG single crystal. The SEM images showed that the grain size in the Dy:YAG ceramic increases with the sintering temperature. There are several emission bands in the photoluminescence spectrum of the Dy:YAG single crystal located at 483 nm in the blue region, 580 nm in yellow region and 670 nm in red region. Dy:YAG is a good candidate crystal for white light emission.

Vertically-aligned WO₃ nanoplates on transparent conducting fluorine-doped tin oxide (FTO) glass were prepared by a facile template-free crystal-seed-assisted hydrothermal method. The effects of the hydrothermal temperature and reaction time on the crystal structure and morphology of the products were investigated by XRD and SEM. The XRD results showed that the as-prepared thin films obtained below 150${}^{\circ }$C comprised orthorhombic WO₃ ⋅ H₂O and completely converted to monoclinic WO₃ at 180${}^{\circ }$C. It was also noted that there was a phase transformation from orthorhombic to monoclinic by increasing the reaction time from 1 to 12 h. SEM analysis revealed that WO₃ thin films are composed of plate-like nanostructures.

This paper studies the fabrication of a novel planar electromagnet consisting of a planar copper coil and a magnetic yoke. CoFeB was used as the magnetic yoke material instead of the traditional permanent magnets. The planar electromagnet was fabricated and optimized to maximize the electromagnetic force, especially with varying CoFeB thickness. The micro-planar electromagnet was fabricated successfully by the traditional micro-electro-mechanical-system (MEMS) techniques and XRD, VSM were used to characterize the performance of the electromagnet. The planar electromagnet exhibits superior perpendicular magnetic anisotropy (PMA) and 0.006 emu of $M_S$ was achieved following 2 min deposition of CoFeB thin film. By integrating with other micro apparatuses, it is anticipated that the planar electromagnet will have potential applications in areas such as biosensors, biological medicine, drug delivery, chemical analysis and environmental monitoring.

The interaction between formaldehyde (HCOH) and pristine single-walled carbon nanotube (SWCNT) fragment was investigated by density functional theory (DFT) to evaluate the detection of HCOH. The simulation results demonstrated less adsorption on surface of SWCNT and doped CNTs, while a HCOH molecule tended to be chemisorbed to the C atom located on SWCNT’s edge positions with larger binding energy of 1.742 eV and smaller binding distance of 1.351 Å. Furthermore, charge transfer and density of states study indicated that the electronic properties changed evidently in the most stable HCOH-SWCNT system, and were mainly around the Fermi level. More importantly, the adsorption of HCOH affected the electronic conductance of SWCNT. It is expected that the results could provide a useful theoretical guidance for the investigation of molecular films interface bonding and design of HCOH sensing devices.

Amorphous rare earth–transitional metal (RETM) GdFeCo memory layer with RE- and TM-rich compositions was fabricated in stacks of GdFeCo (10 nm)/Cu (3 nm)/[Co(0.2 nm)/Pd(0.4 nm)]₆. Their magnetic properties and spin transfer torque (STT) switching of magnetization were investigated. The maximum magneto-resistance (MR) was around 0.24% for the TM-rich Gd${}_{21.4}$ (Fe${}_{90}$Co${}_{10}$)${}_{78.6}$ memory layer and was −0.03% for the RE-rich Gd${}_{29.0}$ (Fe${}_{90}$Co${}_{10}$)${}_{71.0}$ memory layer. The critical current densities $J_c$ to switch the GdFeCo memory layers are in the range of $1.4\times 10^7$ A/cm²–$4.5\times 10^7$ A/cm². The dependence of critical current density $J_c$ and effective anisotropy constant $K_{\mathrm{\text{eff}}}$ on Gd composition were also investigated. Both $J_{\mathrm{\text{c}}}$ and $K_{\mathrm{\text{eff}}}$ have maximum values in the Gd composition range from 21–29 at.%, suitable for thermally assisted STT-RAM for storage density exceeding Gb/inch².

Due to the mismatch between ZnO film and $p$-Si lattice, there are a large number of interface states which seriously affect the photoelectric properties of ZnO/$p$-Si heterojunction optoelectronic devices. In this research, ZnO thin films were deposited on $p$-Si by magnetron sputtering and ZnO/$p$-Si heterojunction was prepared. CuSCN film buffer layer was inserted into the interface of ZnO/$p$-Si heterojunction to reduce the interface state and improve the electric properties of heterojunction. The results show that the insertion of CuSCN films can effectively improve the interface state of ZnO/$p$-Si heterojunction, increase the forward current, reduce the reverse current and improve the heterojunction rectification ratio.

In order to restore image color and enhance contrast of remote sensing image without suffering from color cast and insufficient detail enhancement, a novel improved multi-scale retinex with color restoration (MSRCR) image enhancement algorithm based on Gaussian filtering and guided filtering was proposed in this paper. Firstly, multi-scale Gaussian filtering functions were used to deal with the original image to obtain the rough illumination components. Secondly, accurate illumination components were acquired by using the guided filtering functions. Then, combining with four-direction Sobel edge detector, a self-adaptive weight selection nonlinear image enhancement was carried out. Finally, a series of evaluate metrics such as mean, MSE, PSNR, contrast and information entropy were used to assess the enhancement algorithm. The results showed that the proposed algorithm can suppress effectively noise interference, enhance the image quality and restore image color effectively.

In order to resolve the problems of low efficiency and large separating difference in fault detection of lamp holders with single soldering lug, an image-detection-based defect detection method is presented in this paper. The selected image is first preprocessed, where the possible area of soldering lug is cut in this preprocessing to narrow the scope for subsequent partition with the consideration that the smooth surface of metal at lamp holder and black insulation glass may reflect the light. Then, the soldering lug is extracted by a series of processing including clustering partition. Based on this, the defects are detected by regional marking, area comparison, circularity and coordinate deviation. The experiment results show that the designed method is simple and practical to detect main quality defects of lamp holder with single soldering lug correctly and efficiently.

Cloud obstacles obscure ground information frequently during remote sensing imaging which leads to valuable information losses. Removing clouds from a single image becomes challenging since no reference images containing cloud-free regions are available. In order to study cloud removal technologies and evaluate their performances, a method to simulate evenly and unevenly distributed clouds was proposed by analyzing the physical model of remote sensing imaging. Dual tree complex wavelet transform (DTCWT) and its features were introduced briefly. According to the frequency relationships between clouds and ground objects in remote sensing images, a novel cloud removal algorithm was proposed. The algorithm divided the cloud-contaminated image into low-level high frequency sub-bands, high-level high frequency sub-bands and low frequency sub-band by DTCWT. Low-level high frequency sub-bands were filtered to enhance the ground object information by Laplacian sharpening. The other two types of sub-bands were processed to remove clouds by cloud cover coefficient weighting (CCCW). The experiments were implemented to process cloud disturbed images produced by the proposed simulation method. The results of cloud removal from remote sensing images were analyzed. It proved the proposed algorithm is greatly superior to algorithms based on traditional wavelet transform and dark channel prior.

SiNx thin film has been widely used in crystalline silicon solar cell production because of the good anti-reflection and passivation effect. We can effectively optimize the cells performance by plasma-enhanced chemical vapor deposition (PECVD) method to change deposition conditions such as temperature, gas flow ratio, etc. In this paper, we deposit a new layer of SiNx thin film on the basis of double-layers process. By changing the process parameters, the compactness of thin films is improved effectively. The NH₃ passivation technology is augmented in a creative way, which improves the minority carrier lifetime. In sight of this, a significant increase is generated in the photoelectric performance of crystalline silicon solar cell.

Two $\beta$-Sialons, with $z$-values of 1 and 4, respectively, were successfully synthesized by silicothermal reduction and nitridation method under 0.4 MPa nitrogen pressure. The effect of firing temperatures on the phase transformations and morphologies of $\beta$-Sialons were analyzed by XRD and SEM. For $\beta$-Sialons ($z=1$), the product was finally composed of targeted $\beta$-Sialon ($z=1$) and secondary phase $\alpha$-Si₃N₄; for $z=4$, $\beta$-Sialon ($z=4$) was the main phase, and 15R-Sialon and $\alpha$-Al₂O₃ co-existed as secondary phases. A higher firing temperature is more beneficial for the phase transformations and crystal growth of $\beta$-Sialons, however, the most suitable firing temperature was 1400${}^{\circ }$C.

The effect of point defect on mechanical properties of MoSi₂ has been investigated by the first-principles. The elastic constants, mechanical modulus, hardness and thermodynamic properties of MoSi₂ with four different single point defects have been calculated. By comparing with the defect-free MoSi₂, it is found that the bulk modulus/shear modulus ratio (B/G) of MoSi₂ with a single point defect increases slightly while the Debye temperature decreases drastically, which indicates that MoSi₂ with some point defects have relatively good ductility. The calculated three-dimensional (3D) contours of elastic modulus and these projections on the (001) and (010) planes show that the directionality of Young’s modulus and shear modulus is unapparent for MoSi₂ with a point defect (V${}_{\mathrm{\text{Mo}}}$ and Mo${}_{\mathrm{\text{Si}}}$) but it is relatively obvious for MoSi₂ with V${}_{\mathrm{\text{Si}}}$ and Si${}_{\mathrm{\text{Mo}}}$. It suggests that V${}_{\mathrm{\text{Si}}}$ and Si${}_{\mathrm{\text{Mo}}}$ can strengthen the anisotropy in elasticity. The electronic properties of C11${}_{\mathrm{\text{b}}}$ MoSi₂ with different single point defects have been studied to reveal further the influencing mechanism of point defect on mechanical properties. This work should help reveal the interrelation between intrinsic defects and service performance of MoSi₂.

Two types of black ceramic coatings with high spectrum absorptivity were prepared on Al alloy substrate by using plasma electrolytic deposition method. The spectrum absorption properties of coatings were tested by using 355 nm ultraviolet laser pulses. Particle counter device was employed to collect and analyze the particles formed during the irradiation process. Experimental results showed that the coatings have porous structures. The sample coatings 1 and 2 have thickness of 120 $\mu$m and 60 $\mu$m with holes’ diameter of about 70 $\mu$m and 15 $\mu$m, respectively. The coating 1 is mainly composed of Al₂O₃ and SiO₂ while coating 2 consists of Al₂O₃. The reflectivity of both coatings is much lower than that of Al alloy substrate. The absorptivity of samples 1 and 2 is about 99.88% and 99.92% for wavelength from 300 nm to 800 nm. The mechanisms of spectrum absorption were also explored.

The calcination process was used to remove free carbon and to change the structure of amorphous microsilica powder. The results show that the carbon content in amorphous silica powder strongly depends on the calcination temperature. When the calcination temperature is higher than 900${}^{\circ }$C, the free carbon content, SiO₂ content and weight loss of microsilica powder tend to be stable, with values of 0.05%, 83.8% and 4.8%, respectively. The crystalline structure, particle size and morphology start changing at a calcination temperature of 850${}^{\circ }$C. When the calcination temperature is higher than 900${}^{\circ }$C, the amorphous microsilica powder is fully crystallized. The morphology of the silica fume kept its original spherical shape under 850${}^{\circ }$C, while above 850${}^{\circ }$C the microsilica powder recrystallizes. These results provide a basis for chemical removal of metal impurities in the preparation of high-purity silica powder.

Searching for an economical and effective sand-fixing material and technology is of great importance in Northwest China. This paper described the use of a semihydrated gypsum-(CaSO₄ ⋅ 1/2H₂O-)based composite as a sand-fixing material. Its morphology and composition were characterized by SEM, and its water resistance, freezing–thawing resistance and wind erosion resistance were tested in the field. The results indicated that semihydrated gypsum-(CaSO₄ ⋅ 1/2H₂O-)based sand-fixing composite has good water resistance and water-holding capacity. Its strength is maintained at 1.42 MPa after 50 freezing and thawing cycles, and its wind erosion increases with increasing wind speed and slope. Its compressive strength starts to decrease after nine months of field tests with no change in appearance, but it still satisfies the requirements of fixation technology. This sand-fixing material should have wide application owing to its good weather resistance.

This paper reports the preparation and characterization of eutectic Glauber’s salt-based composite, phase-change materials (G-PCMs). PCMs were prepared using industrial-grade sodium sulfate decahydrate (Na₂SO₄ ⋅ 10H₂O) as the basic material. Other salts were added to obtain the eutectic Glauber’s salt-based PCMs with phase-change temperatures of 25${}^{\circ }$C, 15${}^{\circ }$C and 10${}^{\circ }$C. The modification of the G-PCMs was designed using the same experimental method to select the efficient nucleating, thickening and thermal conductive agents. The results show that borax can be an effective nucleating agent, sodium carboxymethyl cellulose is an excellent thickener and carbon powder is a good thermal conductive agent. The phase-change temperature, latent heat and thermal conductivity of the three different PCMs are 23.9${}^{\circ }$C, 15.4${}^{\circ }$C and 9.5${}^{\circ }$C; 179.6, 129 and 116.2 J/g; and 1.02, 1.10 and 1.23 W/(m K), respectively. These PCMs possess suitable phase-change temperature, high latent heat and good thermal conductivity, and can be used in Qinghai–Tibet Plateau agricultural solar greenhouses.

Chalcopyrite and wurtzite CuInS₂ (CIS) nanomaterials were synthesized from Cu${}^{2+}$, In${}^{3+}$, thiourea with or without triethanolamine (TEA) by simple hot injection method at low temperature. The effect of synthesis duration on the various properties of the synthesized CIS nanomaterials was studied. It shows that for chalcopyrite CIS, the optimal synthesis duration is 60 min and the synthesized nanomaterial is in spherical shape with diameter of about 90 nm. However, for the wurtzite CIS, the optimal synthesis duration should reach 150 min and the synthesized nanomaterial looks like nanoplate with thicknesses of $\sim$10 nm and diameters near 100 nm. The photovoltaic characteristics of two types of nanomaterials are quite different. This study may contribute to the synthesis of CIS nanomaterials at low temperatures.

In order to develop a kind of slurry with low permeability which has some adsorption and retardation to the pollutants in leachate to be used in antiseepage engineering of leachate for landfill site, experiments based on orthogonal method were performed. The optimal PBFC slurry was selected: bentonite 18–26%, cement 16–24%, fly ash 18–20%, TOJ800-10 water reducing agent 0.01–0.03%, polyvinyl alcohol 0.2–0.8%, sodium carbonate 0.8–1.5% and water 680–780/1000 mL seriflus. The material has good groutability and a concretion stone ratio which is greater than 99.6%. The coefficient of permeability of 28-day concretion body is 0.53 × 10${}^{-8}$–1.86 × 10${}^{-8}$ cm/s and the compressive strength is 0.64–1.04 MPa. The slurry has good adsorption and retardation properties. The block rate of NH₄-N and phosphorus reached 98.28%, and the block rate of CODCr and BOD₅ reached 85.67%. The block rate of Hg, Pb and other heavy metal ions reached 99.8%. The PBFC slurry improved the retardation capability of the pollutants of the leachate at the landfill site by its infiltration sedimentation and adsorption fixation.

Phase change material (PCM) is increasingly being applied in the manufacturing of functional thermo-regulated textiles and garments. This paper investigated the thermal buffering performance of different composite PCMs which are suitable for the application in functional low-temperature protective garments. First, according to the criteria selecting PCM for functional textiles/garments, three kinds of pure PCM were selected as samples, which were $n$-hexadecane, $n$-octadecane and $n$-eicosane. To get the adjustable phase change temperature range and higher phase change enthalpy, three kinds of composite PCM were prepared using the above pure PCM. To evaluate the thermal buffering performance of different composite PCM samples, the simulated low-temperature experiments were performed in the climate chamber, and the skin temperature variation curves in three different low temperature conditions were obtained. Finally composite PCM samples’ thermal buffering time, thermal buffering capacity and thermal buffering efficiency were calculated. Results show that the comprehensive thermal buffering performance of $n$-octadecane and $n$-eicosane composite PCM is the best.

Auxetics are materials showing a negative Poisson’s ratio. Early research found several categories of auxetic materials in the chemical field. Later research identified the fundamental mechanism generating this behavior is rotation; a variety of two-dimensional auxetic material have been generated accordingly. Nevertheless, the successful example of three-dimensional auxetic material is still rare. This paper introduces a new design of three-dimensional periodic cellular auxetic material based on geometrical and mechanical methodology. The projections of the optimized periodic modules in two horizontal directions are geometrically same with auxetic hexahedral poem, so that the optimized periodic material can perform auxetic in both two horizontal directions under vertical compression. Parametric model is simulated to prove the design.

The high-ortho epoxy phenolic fibers (HEPFs) were prepared by the crosslinking of as-spun filaments derived from melt-spinning of the epoxy novolac resins copolymerized among epichlorohydrin (ECH), phenol and formaldehyde, and cured in a combined solution of formaldehyde and hydrochloric acid with a different heating rate. The changes in functional groups, thermal performance and mechanical properties during the different heating rates in solution curing were characterized. The results show that a peak of thermal stability and mechanical properties can be obtained with increasing heating rate, and crosslinking structure and characteristic group have changed after the solution curing. The epoxy phenolic fibers show great potential in the application of elastic flame-resistant textiles, aero-composites and precursors for activated carbon fibers used in electronic devices.

Organic soluble poly(substituted-aniline) was synthesized by chemical oxidative polymerization from 2-methyl-6-ethylaniline tar. The structural information of samples was characterized using FT-IR and SEM techniques. The influences of acid concentration, mole ratio of oxidants to tar, reaction time and temperature were investigated. The solubility of polymers was also studied. The results indicate that the conductivity of poly(substituted-aniline) could reach 2.51 ${\times }^{-4}$ S ⋅ cm${}^{-1}$ under the reaction conditions with 1 mol./L hydrochloric acid, mole ratio of oxidants to tar = 1, and at 10${}^{\circ }$C for 3 h. The polymers show better solubility than polyaniline in most organic solvents.

Poly(lactide) (PLA) — flax fibers stereocomplex composites were prepared by casting commercial poly(L-lactide) (PLA) and flax-g-poly(D-lactide) (flax-g-PDLA), where flax-g-PDLA was synthesized via ring-opening polymerization. Successful surface grafting was revealed by Proton Nuclear Magnetic Resonance (¹H NMR) spectroscopy, wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) studies. DSC results showed that stereocomplex crystallites formed between the PLA matrix and flax-g-PDLA, resulting in good fiber/PLA interfacial adhesion.

Ar/H₂O microwave-excited surface-wave plasma-induced grafting-polymerization and crosslinking technique was presented to construct a bio-functional surface layer. Optical emission spectroscopy was used to diagnose Ar/H${}_{\mathrm{\text{2}}}$O plasma. The surface/interface behavior especially the aging effect of hydroxyl groups over the grafted PEG spacer layer was investigated by measuring water contact angle and X-ray photoelectron spectroscopy. The results demonstrate that the addition of water vapor into Ar plasma can optimize the concentration of hydroxyl functional groups on surface; grafted PEG spacer layer can provide a long-term hydrophilicity of PU films, and alleviate the aging effect of hydroxyl functional groups.

In capillary polymer electrophoresis, the property of polymer sieving matrix dominates the migration behavior of DNA/RNA. We investigated the capillary electrophoresis of RNA ranging from 100 nt to 10,000 nt in polyacrylamide (PA) solutions with different molecular weights (Mw) and different concentrations. We observed that the resolution length (RSL) of RNA fragments was improved and the migration time was prolonged, when polymer concentration was increased. The resolution for small RNA fragments ($<$1000 nt) was improved with the increase of polymer concentration, whereas the large ones ($>$3000 nt) became inseparable. In addition, we estimated the smallest resolvable nucleotide length (Ls) by the plot of RSL against RNA size.

Transition metal oxide photocatalysis is a relatively new method representing advanced oxidation process to be applied in industrial wastewater treatment especially for degradation of organic pollutants. We investigate TiO₂ as a photocatalyst for the photocatalytic degradation of Rhodamine B (RhB) under simulated sunlight. Various parameters and their effectiveness have been studied. The effects of processing parameters including catalyst loading and feed concentration were investigated; and the degradation pathway was proposed based on the UHPLC-MS analysis. The result showed that a higher kinetic rate can be obtained by employing low catalyst loading and feed concentration, i.e., 0.5 g/L of TiO₂ loading and 5 ppm of RhB concentration, respectively. For this particular system, the optimum degradation rate ($k$) can achieve 0.297/min. The effectiveness of solar light-TiO₂ system for RhB degradation shows this method can be used for wastewater treatment.

Separation and recovery of valuable metals including silver (Ag) and copper (Cu) from electronic waste mixtures are of great economic and environmental importance. Recent years, semiconductor photocatalysts have been investigated intensively for the removal of Ag from wastewater. Few studies have been carried out on the effect of pH and co-exist metal ions such as Cu on Ag. In this study, ZnO and TiO₂ were applied as photocatalysts to target on the selective recovery Ag and Cu from its mixtures under UV light. The effects of pH, catalyst, ethylene-diamine tetraacetic acid (EDTA) on the Ag and Cu photo-reduction were studied. Modeling of Ag${}^{+}$ and Cu${}^{2+}$ with and without EDTA distribution together with metal precipitations was plotted against pH to understand the chemistry involved in photocatalysis. Experimental results showed that Ag${}^{+}$ photo-reduction was nearly completed by ZnO and TiO₂ to Ag metal, while Cu${}^{2+}$ photo-reduction to Cu₂O only occurs by ZnO in the presence of EDTA. This work illustrates that semiconductor photocatalysts are suitable for selective recovery of Ag and Cu from wastewaters.

High-efficient recycling of solid waste from the semiconductor or textile dyeing industry has been a challenge since these industrial waste not only brings a heavy burden to enterprises but also seriously affects our ecological environment. Here, a feasible method is proposed to recycle this solid waste by transferring it into high value-added ceramsites. They were prepared by using the third grade sand of cutting silicon (TGSCS) and textile dyeing sludge (TDS) as raw materials and composed mainly of SiO₂–Al₂O₃. Through systematic analysis of the experimental results, it was concluded that the optimized ratios of the TGSCS and the TDS should range from 1:1.5 to 1:3, while the sintering temperature should be around 1150${}^{\circ }$C. These lightweight ceramsites can have excellent properties of the cylinder compressive strength of 4.65 MPa and bulk density of 477 kg/m³. The potential expansion mechanism was thought to be related to both TGSCS and TDS as they reacted with Fe₂O₃ impurity to form CO₂/CO gases. This work is to prepare lightweight ceramsites and to recycle solid waste.

Graphene and titanium dioxide (TiO₂) composite catalyst has been synthesized by hydrothermal synthesis method, and used for the degradation of Rhodamine B (Rh.B) in water. The photoelectrocatalytic activity of this composite was evaluated by decomposing of Rh.B in water under visible or UV light irradiation. The degradation results indicated that the photoelectrocatalytic performance of this composite catalyst was greatly enhanced due to the improved adsorption performance and separation efficiency of photo-generated carriers possibly. The composite with graphene content of 10 wt.% exhibited superior activity under UV light irradiation. After 30 min of reaction, the photoelectrocatalytic degradation ratio of Rh.B was about 96% when pH $=$ 6–7. The results of this work provide a good method for the treatment of organic wastewater with high performance.

This work studies the adsorption behavior of methylene blue (MB) from water by bone char (BC). The effects of pH, initial dye concentration and dosage of adsorbent on the adsorption were investigated. It was found that the adsorption capacity of MB was affected by the mount of OH${}^{-}$, initial concentration gradient driving force of MB, the surface charge and adsorption site of BC.