Surface Review and Letters

The present paper reviews various types of coatings, including platinum, platinum alloys, palladium, ruthenium, iridium, nickel, nickel alloys and composite coatings, on superalloy substrates using electrodeposition method. Attempts were carried out to represent an overall view of plating conditions and electrolyte and highlight the importance of the layer regarding to the performance of high-temperature coatings applied on superalloys, which is extensively used on gas-turbine components.

In this work, the microstructure and magnetic properties of carbon–nickel (C–Ni) composite films annealed at different temperatures (300–1000${}^{\circ }$C) were investigated. The films were grown by radio frequency magnetron sputtering on quartz substrates at room temperature. The nickel concentration in the films are affected by changing of the value of evaporation nickel atoms and measured by Rutherford backscattering spectroscopy (RBS). Values of coercive field were measured under both increasing and decreasing applied magnetic field. It is shown that the coercive field of films strongly dependent on the annealing temperature and at 500${}^{\circ }$C films has maximum value of 93.67Oe. The difference in the coercive fields increased for films annealed from 300 to 500${}^{\circ }$C and then decreased from 500 to 1000${}^{\circ }$C. The I_D/I_G ratio of Raman spectra would indicate the presence of higher sp² bonded carbon in the films annealed at 800${}^{\circ }$C.

The multifunctional textiles are interesting areas to be researched on. In this paper, the effect of the fiber nanocoating on the wrinkle recovery, air permeability and anti-Ultraviolet (UV) property of different woven fabrics using sol–gel method has been studied. The sol–gel method has various advantages over other methods. Along with these properties, no change in visual appearance has also been discussed in this paper. The dispersion of nanoparticles of titanium was obtained into silica sol. The characterization of nanocoating was done using Field emission scanning electron micrograph (FESEM) and Fourier transform infrared spectroscopy (FTIR) studies. The fabric wrinkle recovery properties, air permeability and anti-UV performance were analyzed using three different immersion timings into the nanosol. The results revealed that both wrinkle recovery properties and anti-UV performance have increased with respect to immersing time of the nanocoating although a slight decrease in air permeability and whiteness index of the fabric was also observed.

Tungsten thin films were prepared by pulsed laser deposition (PLD) technique on glass substrates placed at the angles of 0${}^{\circ }$ to 70${}^{\circ }$ with respect to the target surface normal. Rutherford backscattering Spectrometry (RBS) analysis of the films indicated that about 90% of tungsten material flux is distributed in a cone of 40${}^{\circ }$ solid angle while about 54% of it lies even in a narrower cone of 10${}^{\circ }$ solid angle. Significant diffusion of tungsten in glass substrate has been observed in the films deposited at smaller angles with respect to target surface normal. Time-of-flight (TOF) measurements performed using Langmuir probe indicated that the most probable ion energy decreases from about 600 to 91eV for variation of $\theta$ from 0${}^{\circ }$ to 70${}^{\circ }$. In general ion energy spread is quite large at all angles investigated here. The enhanced tungsten diffusion in glass substrate observed at smaller angles is most probably due to the higher ion energy and ion assisted recoil implantation of already deposited tungsten.

The effect of substrate on the crystalline phase and morphology of the poly (vinylidene fluoride) (PVDF) thin film has been investigated. The solution of PVDF/Hexamethyl phosphoramide (HMPA) was deposited on four different substrates, namely, silicon (Si), glass (SiO₂), indium tin oxide (ITO) coated glass and silver (Ag) coated glass respectively by using the spin coating technique. The crystalline structure was investigated using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) techniques. The morphology was determined using scanning electron microscopy (SEM). XRD demonstrated that the structure of PVDF thin films on each substrate is $\beta$-phase with different orientations of the molecular chains. FTIR results confirmed XRD that the samples contain $\beta$-phase. SEM shows spherulites structure, which is rough and porous, besides, the size of spherulites and the porosity are different for each sample. The size of spherulites is in average diameter range (1–6$\mu$m) and this range is attributed to the $\beta$-phase. The nucleation process of $\beta$-phase on the various substrates attributed either to the match of polymer-substrate or to the electrostatic interaction. Among the substrates used, the ITO substrate exhibited a greater tendency for $\beta$-phase formation.

In this work, plasma electrolytic oxidation (PEO) ceramic coatings were prepared on magnesium AZ31B alloy. Various electrolyte solutions including phosphate, aluminate and silicate as additives and NaOH $+$ Na₂SiF₆ as constant agent were used to prepare the coatings. Influence of the additives on chemical composition and structure of the PEO coatings were examined by means of scanning electron microscope (SEM) and XRD. From structural analysis it was found that coatings prepared in the aluminate-based electrolyte have the best structural features. Microhardness and tribological characteristics of the PEO coatings were investigated using Vickers hardness test and pin-on-disc test. Microhardness for aluminate-based coating was found to be 1169.63HV while those for silicate-and phosphate-based coatings were 1093.42HV and 285.91HV, respectively. Wear rate of the aluminate-based coating was found to be lowest than all other coatings having a value of $2.78\times 10^{-3}$mg/Nm.

The aim of this study was to investigate the effect of the surface condition of the coulters of a Poznaniak mechanical seeder working in a sand medium on their abrasive wear resistance. Two types of coulter flap surface treatments were performed. The first treatment method was flame spraying, performed with the use of Eutalloy 10112 powder and other method was laser surface modification consisting in remelting a piece of the coulter flap tip by means of TRUMPF’s CO₂ molecular laser. The study involved the use of a purpose-built laboratory test stand dedicated to testing wear in a sandy medium. The study revealed that surface treatment changes surface microstructure and thus improves its hardness by $1.5$ to 3 times, which translates into two- to six-fold improvement in wear resistance per hectare of cultivated field. Laser surface modification is more economical than thermal spraying and that the coulter flap surface area modified by thermal spraying was much greater than in the case of laser remelting, and finally that the average wear measured as a weight loss of tested coulters was comparable, one can conclude that in the analyzed context laser surface modification will probably prove more efficient than flame spraying. The study showed that there exist ready-to-use technologies for improving operational performance and delaying terminal wear.

The Editor has retracted the above article from its publication in Surface Review and Letters due to duplicate publication

This study examines the critical surface energy of manganese sulfite (MnSO${}_3)$ crystalline thin film, produced via chemical bath deposition (CBD) on substrates. In addition, parachor, which is an important parameter of chemical physics, and its relationship with grain size, film thickness, etc., has been investigated for thin films. For this purpose, MnSO₃ thin films were deposited at room temperature using different deposition times. Structural properties of the films, such as film thickness and average grain size, were examined using X-ray diffraction; film thickness and surface properties were measured by and atomic force microscope; and critical surface tension of MnSO₃ thin films was measured with Optical Tensiometer and calculated using Zisman method. The results showed that critical surface tension and parachor of the films have varied with average grain size and film thickness. Critical surface tension was calculated as 32.97, 24.55, 21.03 and 12.76mN/m for 14.66, 30.84, 37.07 and 44.56nm grain sizes, respectively. Film thickness and average grain size have been increased with the deposition time and they were found to be negatively correlated with surface tension and parachor. The relationship between film thickness and parachor was found as $\mathrm{\text{P}}=-0.1856\mathrm{\text{t}}+183.45;$ whereas the relationship between average grain size and parachor was found as $\mathrm{\text{P}}=-0.8911\mathrm{\text{D}}+150.52.$ We also showed the relationships between parachor and some thin films parameters.

In this paper, frequency, temperature, film thickness, surface effects, and various parameters dependence of dielectric susceptibility is investigated theoretically for ferroelectric thin films by the modified Landau theory under an AC applied field. The dielectric susceptibility versus AC applied field shows butterfly-shaped behavior, and depends strongly on the frequency and amplitude of the field and temperature. Our study shows that the existence of the surface transition layer can depress the dielectric susceptibility of a ferroelectric thin film. These results are well consistent with the phenomena reported in experiments.

Ultrananocrystalline diamond (UNCD) films on silicon were prepared by microwave plasma chemical vapor deposition (MPCVD) method using argon-rich CH₄/H₂/Ar plasmas. The graphene sheets synthesized by chemical vapor deposition (CVD) were successfully transferred on to the UNCD surface to fabricate electron field emission (EFE) property-enhanced graphene/UNCD films. The surface morphology, structure and composition of the graphene/UNCD double-layered structures were characterized by scanning electron microscope (SEM), atomic force microscope (AFM), Raman spectroscopy and grazing incidence X-ray diffraction (GXRD). GXRD clearly shows the characteristic diffraction peaks of both diamond and graphene. The Raman spectrum shows the characteristic band of diamond at 1332cm${}^{-1}$ and D, G and 2D bands of graphene at 1360, 1550 and 2610cm${}^{-1}$, respectively. The EFE behavior of the composite films can be turned on at $E_0=2.2$V/$\mu$m, attaining a current density of 0.065mA/cm² at an applied field of 7.3V/$\mu$m.

The overlapping effects on surface roughness are studied when samples are treated by laser shock peening (LSP). Surface roughness of overlapped circular laser spot is calculated by ISO 25178 height parameters. The usually used overlapping styles namely isosceles-right-triangle-style (AAP) and equilateral-triangle-style (AAA) are carefully investigated when the overlapping degree in x-axis (${\eta }_x$) is below 50%. Surface roughness of isosceles-right-triangle-style attains its minimum value at ${\eta }_x$ of 29.3%, and attains its maximum value at ${\eta }_x$ of 43.6%. Surface roughness of equilateral-triangle-style attains its minimum value at ${\eta }_x$ of 42.3%, and attains its maximum value at ${\eta }_x$ of 32%. Experimental results are well consistent with theoretical analysis.

The present study focuses on the metallurgical and corrosion characterization of post weld heat treated duplex stainless steel joints. After friction welding, it was confirmed that there is an increase in ferrite content at weld interface due to dynamic recrystallization. This caused the weldments prone to pitting corrosion attack. Hence the post weld heat treatments were performed at three temperatures 1080${}^{\circ }$C, 1150${}^{\circ }$C and 1200${}^{\circ }$C with 15min of aging time. This was followed by water and oil quenching. The volume fraction of ferrite to austenite ratio was balanced and highest pit nucleation resistance were achieved after PWHT at 1080${}^{\circ }$C followed by water quench and at 1150${}^{\circ }$C followed by oil quench. This had happened exactly at parameter set containing heating pressure (HP):40 heating time (HT):4 upsetting pressure (UP):80 upsetting time (UP):2 (experiment no. 5). Dual phase presence and absence of precipitates were conformed through TEM which follow Kurdjumov–Sachs relationship. PREN of ferrite was decreasing with increase in temperature and that of austenite increased. The equilibrium temperature for water quenching was around 1100${}^{\circ }$C and that for oil quenching was around 1140${}^{\circ }$C. The pit depths were found to be in the range of 100nm and width of 1.5–2$\mu$m.

Effects of buffer salt concentration on the rate of deposition, dominated deposition mechanism and subsequently the structural, morphological, and optical properties of cadmium sulfide (CdS) thin films deposited by chemical bath deposition (CBD) on glass substrate were investigated. The precursors were chosen to be cadmium chloride (CdCl₂) as the cadmium source, thiourea (CS(NH${}_2{)}_2$) as the sulfur source, ammonium nitrate (NH₄NO₃) as the buffer salt and ammonia as the complexing agent and the pH controller. The influence of the NH₄NO₃ concentration on the structure, morphology, film uniformity, stoichiometry and optical properties of CdS thin films was also studied by X-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive X-ray (EDX) spectroscope, uv–visible and photoluminescence (PL) spectroscopes. The XRD studies revealed that all the deposited films exhibited a (002)h/(111)c preferred orientation. The crystallite size was increased from 20nm to 30nm by the increase of concentration of NH₄NO₃ from 0.5M to 2.5M. The morphology of CdS thin films were agglomerated spherical particles consisted of smaller particles. The surface of thin films deposited at the NH₄NO₃ concentration of 0.5M was compact and smooth. The increase of the concentration of NH₄NO₃ decreased the packing density of the films. The optical band gap was in the range of 2.25–2.4eV, which was decreased by the decrement of packing density. The PL spectra showed two peaks centered at 400nm and 500nm which are attributed to violet and band-to-band emissions, respectively.

This work constitutes an analysis of the thermodynamic properties in the ordered metallic surface alloy system Au(111)-($\sqrt{3}\times \sqrt{3}$)$R30^{\circ }$-Pd. The equilibrium structural characteristics as well as the thermodynamic functions are examined by the matching method, associated with real space Green’s function formalism, evaluated in the harmonic approximation. Our numerical results, for this metallic system of surface alloy, show in particular a significant dependence between the thermodynamic properties and the coordination number and the values of the force constants.

Aluminum oxide (Al₂O₃) thin films with Al₂O₃ buffer layer were deposited on Si (100) and Si (111) substrates using RF magnetron sputtering of Al₂O₃ target in Ar atmosphere. The synthesized films were then annealed at the temperature of 400${}^{\circ }$C, 600${}^{\circ }$C and 800${}^{\circ }$C in nitrogen (N₂) environment for 6h. Structural properties and surface morphology are examined by using X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscope (AFM). XRD analysis indicated that different orientation of Al₂O₃ were formed with different intensities due to increase in the annealing temperature. From FESEM cross-section analysis results, it is observed that the thickness of films were increased as the annealing temperature increased. EDX analysis shows that the concentration of aluminum and oxygen on both the Si substrates increased with the increase in annealing temperature. The surface roughness of the films were found to be decreased first when the annealing temperature is increased to 400${}^{\circ }$C, yet the roughness increased when the annealing temperature is further increased to 800${}^{\circ }$C.