International Journal of Modern Physics B

Pure copper (Cu) soldering joints with 304 stainless steel (SS) at different soldering temperatures (240–$350^{\circ }$C) were prepared by using Sn–3.5 Ag (wt.%) as a soldering filler-metal material. The mechanical properties and microstructure evolution were investigated. Sound Cu/304 SS joints were obtained by soldering at 240–$350^{\circ }$C for 90 s and the highest average joint shear strength was $\sim 39$ MPa when brazed at $300^{\circ }$C. The Cu₆Sn₅ and Ag₃Sn phases were typical intermetallic compounds (IMCs) in the joints at a soldering temperature of $240^{\circ }$C. Cu₃Sn IMCs were formed at the Cu/Cu₆Sn₅ interface as the soldering temperature increased to $300^{\circ }$C and above. Shear fracture analysis by scanning electron microscopy (SEM) with energy dispersive spectroscopy showed that the joints fractured mostly inside the Cu₆Sn₅ layers.

The protective coatings on laser-welded joints of Zr–1Nb alloy were prepared by the micro-arc oxidation (MAO) process. The morphology, microstructure and phase composition of MAO coatings at different regions of Zr–1Nb alloy laser-welded joints were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to evaluate the corrosion behaviors of the coatings. The MAO coatings at the fusion zone (FZ) and heat-affected zone (HAZ) were smooth with some small holes, while MAO coatings at base metal (BM) were relatively rough with large holes. The cross-sectional topography at FZ coatings was quite dense with less distribution of pores and cracks, which can effectively improve the protective properties of the coatings. HAZ coatings were divided into outer loose layer and inner dense layer. The BM coating layer possessing many holes was a typical sparse layer structure. The phase compositions of welded joints treated by MAO were diverse at different zones of the joints, but all of them consisted of the monoclinic ZrO₂ and tetragonal ZrO₂ phases. The coatings of FZ had the best corrosion resistance, compared with HAZ and BM. The results of EIS indicated that the thickness and defects of the inner compact layer played a key role in improving the corrosion resistance of the MAO coatings on the surface of the Zr–1Nb alloy laser-welded joints.

The study addresses the dynamic performance of flax fiber-reinforced polymer (FFRP) composites via a series of drop-weight impact tests. The experiment was performed based on ASTM standards by using an instrumented falling weight impact machine. Increasing impact energy was applied on the FFRP specimens until an occurrence of perforation. The effect of composite thickness and impact striker diameter were considered. The results showed that the striker diameter and composite thickness have a significant effect on the impact properties of the composites. It is also revealed the influence factors that control the impact behavior of FFRP composite that will be useful for developing future protective fiber-reinforced composites.

An axial bulking mode of the thin-walled tube is proposed and investigated experimentally, for the purpose of transforming a pulse impact into a controllable impact. Two types of thin-walled circular copper tubes with different structures are designed based on the basic circular tubes (BCTs), namely, the uniform grooved tube (UGT) and the circumferential opening grooved tube (CGT). Then, the impact characteristics of a series of copper tubes are investigated experimentally. Results show that BCTs are compressed into two-fold forms during impact, where compression deformation occurs at the thin-walled section and a fold is formed at each thin-walled section. BGTs, UGTs, and CGTs show different performances in terms of transforming impact, and impact output via CGT can be controlled by modifying its structural parameters.

Tungsten trioxide (WO${}_3)$ nanostructures were synthesized by a simple hydrothermal method. The morphology of WO₃ nanostructures can be varied by adding inorganic ions from alkali metal salts. The effect of inorganic ions on the microstructure and visible-light-driven photocatalytic activity was characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy. Methylene blue (MB) photodegradation experiments showed that the one-dimensional (1D) WO₃ nanorods prepared by the aid of potassium sulfate exhibited the highest photocatalytic efficiency (96.4% in 2.5 h) under visible light irradiation. It is deduced that the excellent photocatalytic property of 1D WO₃ nanorods was mainly attributed to the efficient charge transfer capability, which is promising for practical applications in environmental remediation.

In recent years, the safety of traditional Chinese medicine has gradually attracted consumers’ attention. Therefore, the qualitative and quantitative detection of traditional Chinese medicine has become a hot research topic in recent years. In this paper, we chose prepared Rehmannia root as the research object. By using the fluorescence polarization spectrum and the least-square method, a method for predicting the concentration of traditional Chinese medicine solutions was established. First, we scanned the fluorescence polarization spectra of the prepared Rehmannia root solution to obtain the inner anisotropy and anisotropy of each sample. Then, the least-square method was used to obtain the functional relationship between concentration and anisotropy. Finally, the functional relation was applied to predict the concentration of the prepared Rehmannia root solution. The correlation coefficients of the predicted concentration were 0.9944 and 0.9928, with an average recovery rate of 100.94% and 99.58%, respectively. The results show that fluorescence polarization spectroscopy combined with the least-squares method can quickly and accurately detect the concentration of Rehmannia glutinosa root solution. This provides a new method for the content detection of traditional Chinese medicine components.

Cluster analysis of apple juice is an important method in the quality identification of fruit juice. However, the traditional principal component analysis (PCA) is to reduce the dimension of high dimensional data and to achieve clustering by way of score value. Experiments have found that this clustering method is not suitable for real samples with fluorescence overlap. In this paper, we propose a processing mechanism to optimize the derivative of the fluorescence spectrum. When the derivative is calculated, we can amplify the spectral difference of the similar matter and improve the ability of the PCA to achieve the best effect of clustering. Experiments show that the optimized method for the actual sample classification accuracy rate of 100%, which can fully realize the type of commercially available apple juice beverage distinction and achieve the practical application of quality testing.

In this paper, we used the finite element method to numerically study the possible optical resonance modes in the all-inorganic metal halide perovskite (CsPbX₃, $X=\mathrm{\text{Cl}}$, Br, I) semicircular and circular microcavities. For the semicircular microcavity, the quasi-three-period mode has the highest quality factor among quasi-whispering gallery mode (WGM), two-period mode and four-period mode. The quality factors of the four resonance modes all increase linearly for the larger cavity size. In addition, the circular perovskite microcavities present the WGM patterns with extremely high-quality factors, which indicates that the circular perovskite microcavity has the potential application in the optical microcavity or laser device.

The corrosion fatigue cracks propagation behavior of A7N01P-T4 and A7N01S-T5 aluminum alloys in 3.5 wt.% NaCl solution and air were studied by single side notch corrosion fatigue tests (SNET). The crack growth rate (da/dN) was measured and the crack propagation mechanism was analyzed by scanning electron microscopic analysis. The results showed that the corrosion fatigue cracks growth rate of A7N01S-T5 alloy in air and 3.5 wt.% NaCl solution is faster than that of A7N01P-T4 alloy. The crack propagation follows a mixed intergranular and transgranular mode. The anodic dissolution and hydrogen embrittlement accelerate the propagation of corrosion fatigue crack of 7-series Al alloy in 3.5 wt.% NaCl solution. The corrosion resistance and fatigue crack propagation are related to the strength of the alloys and the density of grain boundaries.

In order to alleviate the agglomeration of nanoparticles in the plating solution, the dispersion effect of binary nanoparticles in Ni–P–Al₂O₃–PTFE composite coating was studied by physical and chemical dispersion methods. The effects of different dispersion methods on the microstructure, hardness and friction coefficient of the composite coating were discussed. Through the performance evaluation of the composite coating, it is found that the effect of using appropriate dispersant and ultrasonic dispersion process is good, which can make the nanoparticles fully dispersed in the solution and evenly distributed in the coating, the composite amount of nanoparticles in the deposition layer is also high. The results show that it has a good effect on improving the wear-resisting and antifriction properties of the composite coatings.

Three types of CFRP/aluminum (Al) alloy riveted joints, single-rivet joint, double-rivet joint and three-rivet joint, were prepared by the riveting technique. The fatigue limit of the three-rivet joint was 27.35 MPa. The fatigue failure mechanism of the joint was that Al alloy cracks on the surface of rivet holes and propagates to fail.

To further clarify the effect of the polishing slurry dispersant on the chemical mechanical polishing (CMP) performance of 304 stainless steel, a series of tests were carried out. The correlation between the material removal rate (MRR), surface roughness of 304 stainless steel, dispersant composition, and their content was investigated under two kinds of polishing slurry (hydrogen peroxide oxidant and ferric chloride oxidant) conditions. The experimental results indicated that the MRR and surface roughness of 304 stainless steel arrived at the maximum when the content of sodium hexametaphosphate dispersant was 1.2% (wt) under the hydrogen peroxide–oxalic acid polishing slurry condition. The values of MRR and surface roughness were 146 nm/min and 10 nm, respectively. The MRR and surface roughness of 304 stainless also reached the maximum value as the content of the propanetriol dispersant was 1.2% (wt) under the ferric chloride–oxalic acid polishing slurry condition. However, the values of MRR and surface roughness were 457 nm/min and 22 nm, respectively. Therefore, sodium hexametaphosphate was recommended as the dispersant of hydrogen peroxide–oxalic acid polishing, and propanetriol was recommended as the dispersant of ferric chloride–oxalic acid polishing slurry condition, according to the above analysis. This study lays a theoretical foundation for the improvement of 304 stainless steel CMP performance.

The SiC single-crystal substrate with ultrasmooth and damage-free properties has potential applications in the field of optoelectronics and microelectronics. Lapping is one of the important processes for ultraprecision machining of the SiC single-crystal substrate. The lapping quality has an important impact on the surface quality, processing time, processing cost and processing efficiency of the subsequent chemical mechanical polishing (CMP) of the SiC single-crystal substrate. In this paper, four kinds of lapping pastes with different ingredients were prepared. The tribochemical action and mechanism of the oxidant in the lapping paste were studied. The results show that NaOH can be used as an oxidant for the tribochemical mechanical lapping of the SiC single crystal. Under the catalysis of iron oxide and frictional force, the tribochemical reaction between the SiC single-crystal substrate and the oxidant NaOH occurred and the silicon oxides (such as SiO${}_2)$, gaseous carbon oxides and other reactants were produced. The surface energy of the SiC substrate was reduced and the material removal rate was improved effectively. These results can provide a reference for further research on the mechanism of tribochemical mechanical lapping.

In this study, various austenitizing temperatures were selected to explore their influence on the microstructure and mechanical properties of Cr–Mo–Ni–V steels. The dissolution of primary carbides during the quenching process and the precipitation behavior of carbides during the tempering process for the steels were investigated using SEM and EDS analyses. As the austenitizing temperature increases from $860^{\circ }$C to $900^{\circ }$C, VC can be dissolved into the matrix, and the pinning effect of VC on prior austenite grains is weakened. The dissolved V in the quenched condition has a retarding effect on the carbide precipitation upon tempering. With the austenitizing temperature increasing, both tensile strength and elongation of tempered steels are increased, as well as the impact toughness.

This paper studies the relationship between plastic damage and the ultrasonic nonlinear coefficient by changing the interior plastic strain of A7N01P-T4 aluminum alloys. An effective evaluation of the plastic damage of tensile test specimens was made by comparing with two different nonlinear ultrasonic detection methods, namely, nonlinear longitudinal wave method and surface wave method. The nonlinear coefficient of the stress wave factor was introduced to characterize the plastic damage for metallic materials. The results showed that with the increasing plastic damage degree, the nonlinear coefficient increased slowly at the early stage of yield hardening (3%) and then increased rapidly at the middle stage (3–5%). It is concluded that the nonlinear longitudinal wave is more suitable for point measurement and its sensitivity is lower than that of the longitudinal wave.

In this study, the problems of the low deposition rate and bath instability in chemical deposition can be effectively solved by using the pulsed current-assisted chemical deposition process when preparing Ni–P alloy coating. Orthogonal experiments were designed by changing the average current density, pulse frequency and duty ratio of the pulses to study their effects on the deposition rate and hardness of the coatings. Compact Ni–P coating with uniform surface morphology and good performance was prepared by parameter optimization. The results show that our method can greatly improve the deposition rate while ensuring the surface quality and performance of the deposited layer.

Corrosion resistance is of practical importance for the application of 2205 duplex steels in chemical industries. For taking an insight into pitting corrosion behavior, electrolysis was employed to distinguish the 2205 duplex steel samples. In the following, X-ray diffraction, scanning electron microscopy and electron backscattering diffraction are used to characterize the regions with superior and inferior corrosion performance, thus constructing the relationship between the microstructure and their corrosion behavior.

The effects of polishing pressure, polishing speed and pH value of the polishing slurry on the chemical activity of quartz glass, the material removal rate (MRR) and surface roughness (Ra) of the workpiece were studied. Using MRR and Ra as evaluation indexes, three factors and four levels of the orthogonal test were used to perform chemical mechanical polishing on quartz glass. By measuring the contact angle between the polishing slurry and workpiece, the influence of different polishing slurries on the chemical activity of quartz glass surface was studied. The processing mechanism of CMP quartz glass was analyzed. The order of important factors affecting MRR of quartz glass was: pressure $>$ rotation speed $>$ pH value; the order of significant factors affecting Ra of quartz glass was: pressure $>$ pH value $>$ rotation speed. The optimum polishing process parameter combination of the MRR was: pressure 27.58 kPa, rotation speed 85 rpm, pH value 12; the optimum polishing process parameter combination of the Ra was: pressure 13.79 kPa, rotation speed 85 rpm, pH value 12. The MRR and Ra of the workpiece are evaluated from the mechanical action of pressure and speed and the chemical action of polishing slurry on the workpiece. The results proved that the effect of the alkaline polishing solution on MRR and Ra of quartz glass is more significant than that of the acidic polishing slurry.

Zeolites with unique framework structure have wide applications, such as ions’ exchangers, molecular sieves and catalysts. This work focused on the synthesis and characterization of zeolite by recycling coal fly ash as the starting material via hydrothermal method. The intermediate phases and final products were characterized by XRF, XRD, FT-IR, SEM and BET techniques. The effects of aging time on the crystallization/transformation of zeolite were discussed. The results showed that the alkali-activated coal fly ash after hydrothermal process could lead to the formation of zeolite Na-P1. Furthermore, the aging treatment benefited the formation of homogenous zeolite Na-P1 with smaller particle size, larger specific surface area, total pore volume and pore size.

A series of Ti/Sb–SnO₂ electrodes were prepared by direct current electrodeposition. The changes of catalytic properties of Ti/Sb–SnO₂ electrodes prepared at different current densities were studied. The surface morphology and catalytic performance of Ti/Sb–SnO₂ electrodes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-performance liquid chromatography (HPLC). The oxygen evolution potentials of the electrodes were measured by linear sweep voltammetry (LSV) at the same time. The results show that the increase of the current density can improve the polarization and the electrolysis reaction of water, changing the surface morphology of Ti/Sb–SnO₂ electrodes. When the current density increases to 30 mA/cm², the porous structure is formed on the electrode surface, which provides more active sites for the Ti/Sb–SnO₂ electrode surface and improves the catalytic ability of the electrode greatly. However, when the current density continues to increase, the catalytic ability of the electrode will decrease. This is because the excessively high current density will lead to the loose structure of the electrode surface, which is not conducive to the improvement of the catalytic efficiency of Ti/Sb–SnO₂ electrodes.

This study is focused on obtaining a comprehensive understanding of the influence of geometry — size and shape — on the indentation response of a large set of piezoelectric small-volume structures such as nanoislands, nanowires and thin films. Using three-dimensional finite element modeling, the complex interplay between the properties of the indented materials and the indentation response of piezoelectric micro- and nanostructures is analyzed. It is demonstrated that: (i) In general, the indentation response of thin film structures tends to be much stiffer than that of the piezoelectric nanoisland and nanowires, resulting in more charges being generated during the indentation of the thin-film structures. (ii) The indentation of the piezoelectric nanowire structures with a spherical indenter whose radius is substantially larger than the width of the nanowires, introduces a combination of deformation modes — structural bulging and indentation-induced compression. The combined effect of two deformation modes produces a maximum in the charges generated during the indentation process on a nanowire structure with a particular aspect ratio (i.e., wire width/wire height), which is greater than that produced in nanoisland and thin films structures with the same characteristic size.

We prepared aluminum–silicon–rare earth (Al–Si–Re) elements alloys for electrical contact applications. Three Si weight percentages (wt.%) — 10%, 20% and 30% — were used, and rare earth (Re) elements were kept at 0.35 wt.%. The spraying forming process was adopted, and high-pressure hot isostatic pressing (HIP) was conducted to obtain the bulk materials from the as-deposited billets. The electrical conductivity of alloys with 10% and 20% Si reached 40% International Annealed Copper Standard (IACS). The hardness of Al–Si alloys significantly increased with Si content and HIP processing times. The hardness of alloy with 30% Si reached $\sim$90 HV. Meanwhile, HIP reduced weight loss in the wear resistance by reducing the microcracks and materials removal. The current study proposes an approach to manufacture Al–Si alloys with high electrical conductivity and high wear resistance.

$\alpha$-Si₃N₄ nanowires were formed by a simple chemical vapor deposition (CVD) method using Si and SiO₂ as raw materials without the addition of metal catalyst. The effect of reaction temperature on the phase composition and morphologies of the nanowires were analyzed by XRD and SEM. The experimental results indicate that a suitable reaction temperature is essential for the final products. At 1400${}^{\circ }$C, small amount of target products were obtained, and some irregular particles were attached on the surfaces of nanowires. When the temperature increased to 1450${}^{\circ }$C, the nanowires were mainly composed of $\alpha$-Si₃N₄ phase, they had smooth surfaces with diameters fluctuating from 50 to 200 nm and lengths from hundreds to thousands of microns. At further high reaction temperature (1500${}^{\circ }$C), $\beta$-Si₃N₄ phase was observed and the nanowires had larger diameters, this was negative for obtaining purity $\alpha$-Si₃N₄ nanowires. The growth process of $\alpha$-Si₃N₄ nanowires was dominantly governed by the vapor–solid mechanism.

In this study, the effects of Al${}_x$CoCrFeNiCu high entropy alloy (HEA) binder on the phase composition, microstructure, hardness, fracture toughness and abrasion resistance of Ti(C, N) cermets prepared by powder metallurgy method were investigated by X-ray diffraction, scanning electron microscopy, mechanical properties and abrasion test. The results showed that the sintered Ti(C, N) cermets exhibit homogeneous core-shell microstructure at 1500${}^{\circ }$C when HEAs with 0.2 at% aluminum were added. The Vickers hardness and fracture toughness of cermet with Al${}_{0.2}$CoCrFeNiCu could reach the peak value of 2235 Kg/mm² and 10.51 MPa$\ast$m${}^{1/2}$ and the fracture morphology showed mixture fracture. The Ti(C, N) cermets with HEA binder exhibited good friction and wear properties.

In this research, four titanium-doped zinc oxide (TZO) thin films were deposited on quartz glass substrates by radio frequency (RF) magnetron sputtering. Three of the samples were annealed at $400^{\circ }$C for 40 mins in N₂, Ar and vacuum, respectively. The microstructure and photoelectric properties of the films were characterized. The results showed that annealing in different atmospheres has a significant effect on the microstructure and photoelectric properties. The structure of all the annealed films remained polycrystalline, with a $c$-axis preferred orientation, and the crystallization quality was improved. In addition, the photoelectric properties were also significantly improved by annealing with the average transmittance in the visible region exceeding 90%, the resistivity reaching $3.32\times 10^{-4}\mathrm{\Omega }\cdot \mathrm{\text{cm}}$. The conductivity enhancement was mainly attributed to the increased mobility of carriers. Annealing in argon had the best effect. Finally, the resistivity of all the samples experienced an initial negligible change followed by an increase as the temperature was raised from 10 to 350 K.

Lead dioxide (PbO${}_2)$ electrodes have been actively studied since their large-scale application in energy storage industries in the late 20th century. In modern industry, PbO₂ electrodes are anodically electrodeposited from the oxidizing and toxic chloride and nitrate systems. In recent studies, the PbO₂ electrodeposition from methanesulfonate medium is widely proposed owing to the large ion solubility and environmental friendliness. The further developments in PbO₂ electrodeposited from methanesulfonate electrolytic system is now becoming increasingly important and its future scale-up applications could be envisaged. In this regard, this review illustrates the recent developments of lead dioxide electrodes prepared from methanesulfonate electrolytes.

The assisted wire filling (AWF) cable-type welding wire (CWW) gas metal arc welding (GMAW) is an innovative welding process in which the wire of CWW GMAW is used as the electrode, and the assisted wire using the arc and molten pool melt. The electrode and assisted wire are with CWW, composed of seven wires, one in the center and others uniformly distributed around it. This paper compares the weld seam appearance, arc shape, arc behavior, electrical parameters, and deposition characteristics of the AWF CWW GMAW and CWW GMAW. The arc shape and electrical parameters of AWF CWW GMAW are similar to the CWW GMAW, in which the welding process was not disturbed by the assisted wire. The AWF CWW GMAW welding wire melting and metal deposition rates are higher than those for CWW GMAW with the same welding parameters. The regular changes of weld width, weld depth, and reinforcement that increased with the increase of welding current are the same as those of the welding seam from CWW GMAW. The AWF CWW GMAW weld depth decreased, and the reinforcement is increased compared with the CWW GMAW under the same current. The tension test of the AWF CWW GMAW button joint meets the requirements of CCS.

Surfacing technology is widely used in material surface modification and repair industries, with the advantages of low dilution rate and high wear-resistance performance. The assisted wire filling (AWF) of cable-type welding wire (CWW) gas metal arc welding (GMAW) is an innovative surfacing method, using CWW as the consumable electrode. The dilution rate and wear-resistance performance were studied in this paper. The results show that the weld penetration of the AWF-CWW-GMAW surfacing layer increased with the increase of welding current, which was consistent with the method of CWW GMAW. The dilution rate of the surfacing layer was about 19% lower than that of the CWW-GMAW with the same parameters. Comparing with the CWW-GAMW method, the sample treated by AFW-CWW-GAMW had a smaller dilution rate of surfacing layer, a less wear loss, a smaller friction coefficient and a higher hardness under the same welding parameters. The alloy element distribution of the surfacing layer was higher than that of CWW-GMAW from the weld to the base metal.

The cable-type welding wire gas (CWW) metal arc welding (GMAW) is an innovative arc welding process with high efficiency and high welding quality. However, there is still a lack of deep research on the molten pool of CWW-GMAW. The behavior of molten pool of CWW-GMAW was studied by both numerical simulations and experiments. The temperature field and flow field in the longitudinal section and across cross-section under the current of 450 A in CWW-GMAW were simulated. The result shows that the isotherm in front of the molten pool is denser than that in the back on the longitudinal section. The arc rotation force causes the velocity of the molten pool in the direction of weld penetration becoming more significant than that of weld width. The rotating momentum of the droplet affects the temperature distribution of the weld width and penetration on the cross-section of the molten pool. The coupling of electromagnetic force and rotating arc force makes the flow field present a clockwise vortex shape. The simulated results of weld geometries of CWW GMAW are in good agreement with the experimental results, indicating the applicability and accuracy of the established model.

The laser-arc hybrid welding was carried out on the marine-use steel, and the effects of primary parameters on weld behavior were investigated. The results show that the weld penetration increased gradually with the increase of laser power. Meanwhile, superior weld formation, penetration and reinforcement were achieved when laser and wire distance was 2 mm. The weld width, penetration and reinforcement were increased with the increase of current, while they were decreased with the increase of welding speed. The influence of laser power on the generated microstructure was analyzed by the observation in junction of weld and heat affected zone (HAZ). The microstructure of HAZ coarsened with the increase of laser power, which is consistent with the hardness distribution trend in HAZ.

The selective laser melting (SLM) process gives a possibility to create complex shape parts. Joining SLM alloy parts to similar or dissimilar alloy parts can overcome some product design limitations such as limited dimensions and residual stress concentration. In this study, successful electron beam joining work on to SLM AISI 304 stainless steel plates was performed. The influence of beam current on the weld bead profile was investigated. Typical welded joints were analyzed by microstructure, microhardness, and tensile tests. The optimal welding parameters were obtained accordingly. A thorough analysis of the element and microstructure distribution in SLM and its influence on the properties of the welded joints were also investigated.