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The wrought nickel–chromium–cobalt Nimonic 90 alloy is widely used in turbine blades, piston rings and forged tools due to their high stress-rupture strength and creep resistance up to 920∘C. The application components showed unavoidable wear behaviors at high loads due to the reduced resistance of the components. Hence, in order to increase the wear resistance of this alloy, Inconel 625 and Nimonic 90 particle depositions have been carried out on Nimonic 90 substrate through the laser-cladding techniques to study the microstructure, mechanical and tribological behaviors of alloys. The phases, microstructure and microhardness of the claddings were investigated by X-ray diffractometry (XRD), Transmission electron microscopy (TEM), Scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDS) and hardness test, respectively. Results showed that the mean thickness of the interfacial layer of Inconel 625 and Nimonic 90 was 18.51 ± 4 μ m and 90.68 ± 7 μ m, respectively. The microstructure of the cladding surfaces resulted in dendritic and interdendritic structures. An overall analysis found that the gamma-Ni and hard laves phases were presented in Inconel 625 and Nimonic 90 clad surfaces, respectively. Nimonic 90 clad surface had a high hardness and wear resistance compared with Inconel 625 clad surface and substrate due to the present hard laves phase. Besides, the roughness of the Nimonic 90 clad surface was lower compared with the Inconel 625 clad surface and substrate. [ABSTRACT FROM AUTHOR]

In this study, La2Zr2O7, Yb2O3 and Gd2O3-doped La 1. 4 (Gd, Yb) 0. 6 Zr2O7 thermal barrier coatings have been manufactured from the crystalline and amorphous feedstock by plasma spraying. The thickness of the bond coat is 100±25 μ m and the thickness of the top coat is 250±25 μ m. Thermal shock tests were carried out in furnace temperature of 1200∘C. The thermal shock tests indicate that lifetime of the La 1. 4 Gd 0. 6 Zr2O7 coating has 55 cycles which is the highest thermal shock lifetime compared to other coatings in this study. The type of feedstock, amorphous or crystalline, strongly affects the thermal shock lifetime of La2Zr2O7 coatings. Coating damage after thermal shock tests was investigated using scanning electron microscope to observe the microstructure and X-ray diffraction techniques to analyze the phase composition. The failure of coatings is mainly in consequence of the accumulation of stress between bond coat–ceramic coat interface due to thermal expansion coefficient differences and thermally grown oxide layer formation during thermal shock cycling tests. [ABSTRACT FROM AUTHOR]

Hypereutectic Al-Si alloys are widely utilized in the automotive industry due to their high strength-to-weight ratio, minimal thermal expansion, and superior castability. The downside of hypereutectic Al-Si alloys is the formation of coarse primary silicon particles. The primary Si phases were controlled by the growth-hindering agents, phosphorus (refiner), and strontium (modifier) by using a conventional stir casting technique at room temperature. The microstructural changes were observed through an optical microscope and SEM analysis. The additions of 0.08% P have ensured the formation of the uniformly distributed fine-grained particles in the alloy. The primary silicon particle size was reduced from 220 μ m to 150 μ m as compared to the untreated alloy. The tensile and yield properties of the treated alloy were increased by 12.7% when compared to the untreated alloy with a hardness of 131 BHN. The treated alloy imparted better impact toughness, ensuring a ductile mode of failure through the fractography studies. The influence of the microstructure on the machinability of the alloy was investigated in a dry environment with uncoated and coated inserts (code: CCGT 09T304 FL K10) by varying the process parameters, i.e. speed, feed rate, and depth of cut (DoC). Modification of the primary and eutectic Si phases of an Al-20Si hypereutectic alloy increases machinability with coated inserts as well as its mechanical properties. [ABSTRACT FROM AUTHOR]

Metal-based functionally graded coatings have proven effectiveness in improving anti-wear properties and surface integrity of the substrates. The use of electrodeposition coating technique, considering the economics and versatility associated with this method, is a preferred technique of depositing metal-based composite coatings. Further, Ni-based composite coatings are proven for anti-wear applications, and addition of various reinforcement for developing functional coatings need to be evaluated for different applications. This study describes the development, analysis, and performance evaluation of Ni–TiN–AlN and Ni–SiC–Cr electrodeposited composite coatings on tungsten carbide (WC) tool substrates, to impart improved anti-wear properties during machining. The composite coatings were deposited and optimized for current density values of the electrodeposition process, which was identified as the most significant parameter in both the cases. The coatings were characterized using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) for microstructural analysis. The results were further analyzed for tribological behavior through microhardness and adhesion strength tests of the deposited coatings, which are significant properties imitating anti-wear characteristics of the substrate. A significant increase of 47% and 36% in microhardness was obtained for Ni–SiC–Cr coated specimen and Ni–TiN–AlN coated specimen, respectively, compared to the uncoated WC substrates, accompanied with a good adhesion strength in both the cases. The microstructural analysis in both the cases revealed an increase in the deposited coating constituents with increasing current density, leading to a denser coating deposition up to the saturation point, and then beginning of coating delamination due to over-saturation with further increase in current density. [ABSTRACT FROM AUTHOR]

Taking the high volume fraction SiCp/6061Al-based composite material prepared by the powder metallurgy method under different sintering temperatures and holding times as the research object, the microstructure and interface actions are investigated by X-ray diffractometer, scanning electron microscope, transmission electron microscope, etc. The results show that as the sintering temperature increases, the interface reaction between SiC and Al intensifies, producing brittle phase Al4C3 and MgAl2O4 and MgO interface products. The nucleation and growth of Al4C3 are controlled by the sintering temperature and time. When preparing large-size workpieces with high volume fraction SiCp/6061Al-based composite materials, the sintering temperature should be controlled below 6 7 0 ∘ C, and the holding time should not exceed 24 h. [ABSTRACT FROM AUTHOR]

In this paper, the high-temperature oxidation resistant coating on the TA15 titanium alloy by laser cladding (LC) of the KF110-B4C-Ag mixed powders was analyzed in detail. The scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDS) images indicated that a good metallurgy bond between the fabricated coating/TA15 was formed; also the fine/compact microstructure was produced after a cladding process. The oxidation mass gain of TA15 was higher than that of the coating after LC process, which were 3.72 and 0.91 mg ⋅ cm − 2 , respectively, at 60 h, greatly enhancing the high temperature oxidation resistance. [ABSTRACT FROM AUTHOR]

g–C3N4 nanosheets were first synthesized by calcining the mixture of hydrochloric acid-pretreated melamine and ammonium chloride. Then, by the aiding of solvothermal method and hydrofluoric acid as morphology modifier, 001-TiO2/g–C3N4 (TCN-X, X = 5 , 3, 2, 1) nanocomposites were synthesized using g–C3N4 nanosheets and tetrabutyl titanate, with the mass ratio of g–C3N4 to TiO2 was 5:1, 3:1, 2:1 and 1:1, respectively. The as-synthesized samples were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption–desorption method, ultraviolet–visible diffuse reflectance spectrum, photoluminescence spectrum, etc. Their photocatalytic properties were evaluated under visible light irradiation with rhodamine B (RhB) as the target pollutant. The results reveal that the TCN-3 composites had a large specific surface area of 67.38 m2/g and consisted of g–C3N4 nanosheets and anatase TiO2 crystals about 10–20 nm in size. The (001) crystal planes of TiO2 can be easily observed in TCN-X composites. All TiO2/g–C3N4 composites exhibited excellent photocatalytic activity compared with the pure g–C3N4 did. The photocatalytic property of TCN-X samples varied with the mass ratio of g–C3N4to TiO2, and TCN-3 presented the optimum photocatalytic performance. In total, 50 mg of TCN-3 completely degraded 50 mL and 100 mL of RhB solution (10 mg/L) in 15 min and 40 min, respectively. The reaction rate constant of TCN-3 was 6.7 times as large as that of pure g–C3N4. TCN-3 also presented outstanding activity for the photocatalytic degradation of the colorless tetracycline solution. The significant improvement in photocatalytic activity of TCN-3 was attributed to the evenly distribution of TiO2 on g–C3N4, the enhanced specific surface area and the construction of 001-TiO2/g–C3N4 heterojunction between the g–C3N4 nanosheets and the (001) crystal planes of anatase TiO2, which greatly reduced the recombination rate of the photo-generated electron and hole. In this work, the g–C3N4 nanosheets were obtained by simple mixing and calcination of ammonium chloride and acid-treated melamine. Then, using tetrabutyl titanate as the precursor and hydrofluoric acid to expose the 001 crystal face of TiO2, 001-TiO2/g–C3N4 composite materials with different mass ratios were synthesized by simple hydrothermal method. The composite exhibited excellent photocatalytic performance and degraded RhB within 15 min. The rate constant of TiO2/g–C3N4 composite is 6.7 times that of pure g–C3N4. [ABSTRACT FROM AUTHOR]

In this study, Hardox 400 steel used as substrate material was coated through solid media Thermoreactive Diffusion (TRD) method using Ferro Niobium and Ferro Boron powders from carbide forming element powders. Coating was carried out in three different temperatures (9 5 0 ∘ C, 1 0 0 0 ∘ C and 1 0 5 0 ∘ C) and three different time intervals (1, 2 and 3 h). Microstructures of the coated specimens were examined by optical microscope, Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDX) and X-ray Diffraction (XRD); and hardness values were measured. The effects of coating parameters on coating thickness and hardness were analyzed by ANOVA. In addition, specimens were subjected to wear tests to determine the effect of hardness and coating parameters on wear. In the wear tests, Taguchi test design setup was used. The obtained results were compared with the Hardox 400 steel used under current conditions. It was seen from optical microscope and SEM images that Hardox 400 steel surface could be coated with TRD method depending on coating parameters. The average thickness of NbC–B coating ranged from 1.797 μ m to 5.596 μ m under different process temperature and time. Rising the coating time and temperature increased the coating thickness by 311.40%. EDX analysis showed that the coating layer was composed of B, C, Fe and Nb elements, and XRD analysis also showed that the phase in the coating layer is NbC–B. The NbC–B phase was determined to be an important factor in increasing the hardness. The coating hardness is enhanced by 320.80% depending on the coating parameters. Optimum coating thickness, hardness and wear results were obtained from high coating temperature and time. Uncoated Hardox 400 steels were worn out more compared to the coated Hardox 400 steels. The contribution of coating temperature and time to wear resistance was 1.46% and 8.02%, respectively. It was observed that the important parameter for wear volume was the applied load. [ABSTRACT FROM AUTHOR]

The magnetic properties and microstructures of electrodeposited Co–Ni–Fe–Gd thin films have been investigated for various concentrations of Mn. Nanocrystalline Co–Ni–Fe–Gd alloy thin films were deposited by electrodeposition method on copper substrate with different concentrations of Mn. Microstructures of the deposited Co–Ni–Fe–Gd films were investigated with scanning electron microscope (SEM) and different morphologies such as one-dimensional flower-like crystallites and two-dimensional plate-like crystallites were observed. The Co–Ni–Fe–Gd alloy films exhibit both soft and hard magnetic properties as the Mn ion concentration is varied and the best soft magnetic character is obtained when Mn concentration is 0.1 M, which may be a good candidate for MEMS and recording media. [ABSTRACT FROM AUTHOR]

Aluminum alloy 6061(AA6061) sheets of 4 mm in thickness are joined by laser wire-filling welding (LWFW) using the ER4047 welding wire. Microstructure and alloy element distributions near the fusion line are characterized and are investigated by optical microscope, scanning electron microscope, energy dispersive spectrometer. The results showed that the well-formed welded joints are obtained with a few thermal cracks near the fusion line. The coarse grain and a reduction in the weight ratio of magnesium to silicon can be observed, when the welding speed decreases under constant laser power. The thermal crack is caused by the decrease of the weight fraction of magnesium and the proportion of silicon content has an effect on the microhardness of welded joints. By properly controlling the welding speed, the various properties of AA6061 LWFW joints can be balanced. [ABSTRACT FROM AUTHOR]

Ti-6Al-4V alloy is restricted in industrial application as a result of its relatively low hardness and poor tribological properties. However, the limitations associated with Ti-6Al-4V in severe tribological conditions can be improved via laser cladding technique. In this study, the influence of rare earth oxide (CeO 2) addition on microstructure, hardness and tribological behavior of laser-clad titanium–cobalt-based coatings on Ti6Al4V alloy was investigated. The optimized parameters used for laser depositions are laser power 900 W; beam spot size 3 mm; powder feed rate 1.0 g/min; gas flow rate 1.2 L/min while laser scan speed was varied at 0.6 m/min and 1.2 m/min. Thereafter, the coating morphology as well as wear mechanism of the coatings of CeO2 particles (5–10 wt.%) dispersed in TiCo matrix were investigated via scanning electron microscope (SEM) equipped with energy dispersed spectrometry (EDS), whereas the intermetallic phases present in the coatings were observed using Philips PW1713 X-ray diffractometer (XRD). Furthermore, the micro-hardness values of the coatings were recorded while wear test was carried out using a reciprocating set up (UMT-2 — CETR tribometer). Results revealed that the incorporation of CeO2 particles into the melt pool influenced the morphology of the coatings, thus resulting in finer cellular dendrites, homogenous and strong metallurgical bonding between the laser cladded coating and the substrate. The phases revealed various fractions of interdendritic compounds (CeCo2, Ni3Ti, Co2Ti, CoTi, Al2O3, TiO, AlTi3, and Ce2O 3) dispersed within the coating matrix, thus resulting in 2.68 times improvement on the surface hardness and 47.4% reduction in friction coefficient in comparison with Ti-6Al-4V alloy. [ABSTRACT FROM AUTHOR]

The high energy density beam welding techniques, such as laser and electron beam welding process, have been widely used in industrial applications. In this study, the butt structures of Ti-6Al-4V alloys with the thickness up to 8 mm are successfully joined by the laser welding process. The macromorphology and microstructures of the welded joints are investigated by a scanning electron microscope (SEM). The penetration increases from 5.91 mm to 9.37 mm with the decrease of welding speed from 1.2 m/min to 0.8 m/min under the condition of equal laser power. The acicular α ′ is formed in the fusion zone, resulting from high cooling rate during the process. The metallurgical porosity formation is proposed by investigating the distribution of Al and H elements around the pores. It is concluded that the pores in the weld bead are induced by aluminum vapor and hydrogen gas from the molten pool. The diameter of metallurgical pore has a tendency to increase with the decrease of welding speed. [ABSTRACT FROM AUTHOR]

In this paper, for Q235 carbon steels in NaNO2 solutions with different concentrations of NO 2 − , a passive film composed of mainly Fe2O3 was formed on the Q235 surface, and the effects of NO 2 − concentrations on the properties of passive film were studied by electrochemical methods and microstructural analyses. The applications of electrochemical impedance spectroscopy (EIS), Mott–Schottky (MS) plot, scanning electron microscope (SEM) and X-ray photoelectron spectroscope (XPS) were carried out to characterize the resistance, defect, morphology and composition of passive film, respectively. The passive film resistance and defect, respectively, increased and decreased with the increase of NO 2 − concentration until the NO 2 − concentration was up to 0.01 M, which was the critical NO 2 − concentration of stable passivation for the Q235 surface. The relation between the electrochemical behavior and the passive film was also discussed in detail. [ABSTRACT FROM AUTHOR]

Calcium doped Ni–Zn ferrites having the nominal composition Ni 0. 6 Zn 0. 4 − x Ca x Fe 2 O 4 (x = 0, 0.1, 0.2, 0.3 and 0.4) are prepared via the conventional ceramic method at 1 2 5 0 ∘ C for 3 h to study their physical, electrical and dielectric properties at high frequencies which have extended their applications. The X-ray diffraction (XRD) and scanning electron microscope (SEM) have been used to characterize the microstructure and surface morphology of the prepared composition. XRD patterns reveal the formation of pure spinel phase ferrites whereas SEM micrographs display nonhomogeneous grains of polyhedral shape. The studies disclose that with increasing Ca content in spinel, the lattice parameter of the Ni–Zn ferrite increases and at the same time the grain boundary also increases. As a result of the increased boundary, the large grains could be trapped pores inside the grains which have affected the density, resistivity and dielectric constant of the sample. The DC electrical resistivity of the prepared sample decreases with the increase of Ca content. Also, the resistivity decreases with increasing the temperature. This increase in the conductivity with temperature must be regarded mainly as due to the thermally activated mobility of charge carriers, but not to a thermally activated creation of these carriers. The dielectric constant decreases with the increasing frequency following the Verway-de-Boer hopping mechanism. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The effect of rare earth element neodymium (Nd) addition on the microstructure and martensitic transformation behavior of NiTiNd ( = 0, 0.1, 0.3, 0.5 and 0.7 at.%) shape memory alloy was investigated by scanning electronic microscope, X-ray diffraction and differential scanning calorimetry. The results show that the microstructure of Ni-Ti-Nd ternary alloy consists of NiNd phase, NiTi2 and the NiTi matrix. A one-step martensitic transformation is observed in the alloys. The martensitic transformation temperature Ms increases sharply increasing 0.1-0.7 at.% Nd content is added. [ABSTRACT FROM AUTHOR]

In the present study, the effects of carburization treatment on the microstructure and corrosion property of medium-carbon steels (40Cr) were investigated by means of X-ray diffraction (XRD), electron microprobe analyzer (EMPA), optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and electrochemical corrosion, respectively. It was found that the microstructures beneath the surface were refined and a smooth transition microstructure from the surface to the core was observed in carburized samples. The fine plate-like but not granular carbide precipitation (Cr7C3) was observed in carburized sample by heat-treatment. The carburized specimens exhibited some effectiveness in the improvement of hardness and a smooth transition hardness profile. Corrosion resistance of 40Cr was improved by carburization treatment, resulting in the higher self-corrosion potential and the lower self-corrosion current density. [ABSTRACT FROM AUTHOR]

Corrosion resistant Fe–Al/Al2O3 duplex coating for pipeline steel X80 was prepared by a combined treatment of low-temperature aluminizing and micro-arc oxidation (MAO). Phase composition and microstructure of mono-layer Fe–Al coating and Fe–Al/Al2O3 duplex coating were studied by X-ray diffraction (XRD), scanning electron microscope (SEM) with energy dispersive spectrometer (EDS). Corrosion resistance of the coated pipeline steel X80 in a simulated oil and gas well condition was also investigated. Mono-layer Fe–Al coating consists of Fe2Al5 and FeAl, which is a suitable transitional layer for the preparation of ceramic coating by MAO on the surface of pipeline steel X80. Under the same corrosion condition at 373 K for 168 h with 1 MPa CO2 and 0.1 MPa H2S, corrosion weight loss rate of pipeline steel X80 with Fe–Al/Al2O3 duplex coating decreased to 23% of original pipeline steel X80, which improved by 10% than that of pipeline steel X80 with mono-layer Fe–Al coating. It cannot find obvious cracks and pits on the corrosion surface of pipeline steel X80 with Fe–Al/Al2O3 duplex coating. [ABSTRACT FROM AUTHOR]

The composite coatings were fabricated by laser cladding Al/TiN pre-placed powders on Ti–6Al–4V substrate for enhancing wear resistance and hardness of the substrate. The composite coatings were analyzed by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The sliding wear tests were performed by MM200 wear test machine. The hardness of the coatings was tested by HV-1000 hardness tester. After laser cladding, it was found that there was a good metallurgical bond between the coating and the substrate. The composite coatings were mainly composed of the matrix of β-Ti (Al) and the reinforcements of titanium nitride (TiN), Ti3Al, TiAl and Al3Ti. The hardness and wear resistance of the coatings on four samples were greatly improved, among which sample 4 exhibited the highest hardness and best wear resistance. The hardness of the coating on sample 4 was approximately 2.5 times of the Ti–6Al–4V substrate. And the wear resistance of sample 4 was four times of the substrate. [ABSTRACT FROM AUTHOR]

Calcium silicate (CaSi03) is a promising material due to its favorable biological properties. However, it was difficult to fabricate ceramic scaffolds with interconnected porous structure via conventional technology. In present study, CaSi03 scaffolds with totally interconnected pores were fabricated via selective laser sintering (SLS). The microstructure, mechanical and biological properties were examined. The results revealed that the powder gradually fused together with the reduction of voids and the elimination of particle boundary as the laser power increased in the range of 3-15 W with scanning electron microscope. Meanwhile the low-temperature phase(β-CaSi03) transformed into high-temperature phase (a-CaSi03) gradually, which decreased the mechanical properties of the obtained scaffolds. Besides, the compressive strength increased from 12.9 ±2.34 MPa to 18.19± 1.24MPa (the laser power is 12 w) and then decreased gradually with increasing laser power. In vitro biological properties of CaSi03 scaffolds sintered under optimal conditions indicated that the distribution of apatite mineralization became uniform as the amount of them increased after being immersed in simulated body fluids. In the meantime, the thin cytoplasmic extensions of MG-63 cells increased until formed a dense cell layer after 1-5 days of cell culture. The results suggested that the CaSi03 scaffold fabricated via SLS has potential application for bone tissue engineering. [ABSTRACT FROM AUTHOR]

Ba4LaTi0.3Sn0.7O15 ceramic was prepared through conventional solid state mix oxide route followed by characterization using X-ray diffraction (XRD) and scanning electron microscope (SEM) for phase and microstructural investigation. The dielectric properties at low and microwave frequencies were measured using LCR meter and vector network analyzer. XRD results revealed single phase ceramics and the microstructure was comprised of compact grains with size ranging from 4–12 μm. The lattice parameters refined by the least squares method were a = b = 5.7680(2) Å, c = 11.7491(6) Å, V = 337.81 Å3 and Z = 1. Optimum properties i.e., εr~44.6, Qufo~15, 500 GHz and τf~2.05 ppm/°C were achieved for Ba4LaTi0.3Sn0.7 Nb3O15 ceramic sintered at 1475°C for 4 h. [ABSTRACT FROM AUTHOR]

For the first time, pyromilling synthesis for production of nanocrystalline titanium carbide was presented in this research. Raw materials containing stoichiometric ratio of titanium and carbon were milled and heated simultaneously. Samplings were done at different times. Then, phase transformation, crystallite size and strain of samples were estimated by XRD technique. Microstructures of milled samples were studied by SEM and TEM. Results showed that by increasing temperature, milling time for synthesizing of titanium carbide was reduced. Crystallite size of milled samples were in nanometer scale which were reduced by increasing of milling time and decreasing of temperature while strain was intensified. Existence of created strain changed lattice parameter of synthesized titanium carbide from standard value. This study aims at presenting pyromilling synthesis as a new method for production of titanium carbide in nanometer scales. This method is based on simultaneous application of milling and heating processes. Titanium and carbon powder were milled in different times and temperatures. The results obtained from X-ray patterns showed that an increase in temperature entails a reduction in milling time for synthesizing titanium carbides. Moreover, it is proved that the size of synthesized carbide titanium crystals were in nanometer scale which were decreased by an increase in the milling time and a decrease in the temperature. [ABSTRACT FROM AUTHOR]

In situ synthesized TiC reinforced composite coating was fabricated by laser cladding of Al-Ni-Cr-C powders on titanium alloys, which can greatly improve the surface performance of the substrate. In this study, the Al-Ni-Cr-C laser-cladded composite coatings have been researched by means of X-ray diffraction, scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). There was a metallurgical combination between the Al-Ni-Cr-C laser-cladded coating and the Ti-6Al-4V substrate, and the micro-hardness of the Al-Ni-Cr-C laser-cladded coating was in the range of ~1200-1450 HV0.2, which was ~3-4 times higher than that of Ti-6Al-4V substrate. Furthermore, the reinforcement of theAl-Ni-Cr-C laser-cladded coating were mainly contributed to the action of the TiC, Ti3Al, Cr7C3, Al8Cr5 phases and the solution strengthening. [ABSTRACT FROM AUTHOR]

Laser cladding of the Fe3Al + B4C/TiN + Al2O3 pre-placed powders on the Ti-6Al-4V alloy can form the Ti3Al/Fe3Al + TiN/TiB2 composite coating, which improved the wear resistance of the Ti-6Al-4V alloy surface. In this study, the Ti3Al/Fe3Al + TiN/TiB2 composite coating has been researched by means of X-ray diffraction and scanning electron microscope. It was found that during the laser cladding process, Al2O3 can react with TiB2, leading to the formations of Ti3Al and B. This principle can be used to improve the Fe3Al + B4C/TiN laser-cladded coating on the Ti-6Al-4V alloy. Furthermore, during the cladding process, C consumed the oxygen in Fe3Al + B4C /TiN + Al2O3 molten pool, which retarded the productions of the redundant metal oxides. [ABSTRACT FROM AUTHOR]

The microstructures and mechanical properties of Ni50-xTi43+xAl6Mo1 (x= 0.5, 1, 1.5, 3.5, 5.5 and 7 at. %) alloys have been investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and compressive tests. We found that the variation of Ni/Ti ratio is the predominant reason for affecting the yield stress. The yield stress at room temperature of Ni-rich and Ti-rich alloys was higher than that of the equi-atomic alloy due to the strong solid solution hardening caused by the variation of Ni/Ti ratio. The size and volume fraction of Ti2Ni phase decreased with increasing Ni/Ti ratio. The yield stress at 600°C and 700°C increased with the increasing volume fraction of Ti2Ni phase due to the precipitation hardening effect. The precipitation hardening effect was weakened with increasing temperature. For the Ti-rich alloy deformed at 800°C, the yield stress deceased with the increasing of Ni/Ti ratio due to the reduced strength and unfavorable distribution of Ti2Ni. [ABSTRACT FROM AUTHOR]

In this study, the peening behavior of shot particles in a fine particle peening (FPP) process such as velocity and impact angles were analyzed by using a high-speed-camera. Results showed that the velocity of shot particles depended on a peening pressure; the higher the peening pressure, the higher the particle velocity. The particle velocity measured in this study was approximately 120 m/s; this was much higher than that of the conventional shot peening (SP) process. This was because the air resistance of shot particles in the FPP process was higher than that of shot particles in the SP process. In order to discuss the surface modification effect of the FPP process, commercial-grade pure iron treated by the FPP process was characterized by micro-Vickers hardness tester and scanning electron microscope (SEM). Thickness of hardened layer treated with higher peening pressure was much higher than that of the lower pressure treated one. The unique microstructure with stratification patterns, which was harder than that of the other part, was observed near the specimen surface. The reason for the microstructural changes by the FPP treatment was discussed based on the kinetic energy of shot particles. [ABSTRACT FROM AUTHOR]

The microstructure and magnetic properties of Mg–Cu–Zn ferrites prepared by using solid-state reaction method have been investigated. X-ray diffraction (XRD), a scanning electron microscope (SEM), impedance analyzer and a vibrating sample magnetometer (VSM) were utilized in order to study the effect of copper substitution and its impact on the crystal structure, grain size, microstructure and magnetic properties of the Mg–Cu–Zn ferrite. The formation of cubic spinel phase was identified using XRD technique. The microstructures of the samples show that the grain growth is greatly enhanced by the addition of CuO which is attributed to the liquid phase during sintering. The average grain size (Dm) increases significantly with increasing Cu content. The initial permeability (μ') of the samples increases appreciably with increasing Cu content which is attributed to the increase of grain size and density of the samples. The resonance frequency (fr) of the samples shifts toward the lower frequency as the Cu content increases. The sharp fall of μ' in μ'-T curves is observed for all the samples which indicate the homogeneity of the samples. The saturation magnetization (Ms) of the Mg–Cu–Zn ferrites increases slightly with increasing Cu concentration. [ABSTRACT FROM AUTHOR]

TiC-based wear resistant coating was prepared by plasma spraying using reconstituted composite powders doped with ultra-fine carbide. Phase composition and microstructure of as-sprayed coating were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) utilizing backscattered imaging mode (BSE), and electron probe micro-analysis. Wear test was performed by using a ring-on-block tester under dry sliding condition. Results show that the coating adheres well to the substrate and no delamination appears. TiC content underwent pronounced reduction because of oxidation, reaction, and physical loss. Reactions between TiC and Mo and probably between dissociated C and Mo lead to the formation of Mo2C. Wear resistance of NiCrMo–TiC coating is about 4–8 times higher than that of substrate under different applied force. This work shed light on the reconstitution of spraying powder doped with ultra-fine reinforce phase particles, and the present results are important for the preparation of nano-doped TiC-based coatings. [ABSTRACT FROM AUTHOR]

The effect of nano size Ag addition on the YBa2Cu3O7-δ (Y-123) system has been investigated. 2–15% weight of nano size Ag was added to the Y-123 system prepared by using the sol-gel-solid-state method. The phase purity was investigated by the powder X-ray diffraction method. Energy Dispersive X-ray Analysis (EDAX) was used to determine the distribution of nano Ag in the samples, and the microstructure was observed using a Scanning Electron Microscope (SEM). The transport critical current density was found to increase with increase in nano Ag content. [ABSTRACT FROM AUTHOR]

Indium tin oxide (ITO) thin films were prepared by radio frequency (RF) magnetron sputtering and under a quite low vacuum level of 2.3 × 10-3Pa. The sputtering was done in an Ar and O2 gas mixture at a temperature of 200°C. A ceramic In2O3:SnO2 target (10 wt% SnO2) was used. The microstructures of the films were investigated by a field emission scanning electron microscope (FESEM) and an X-ray diffractometer (XRD). X-ray photoelectron spectroscopy (XPS) was performed to characterize the composition of the films. ITO films with a high transparency in the visible wavelength range (80–95%) were obtained. The dependency of the electrical, optical and structural properties of ITO films on both the O2 flow ratio (O2/(O2 + Ar)) and the working pressure was investigated. In the case of low working pressure (1 Pa), the more highly transparent and conducting films were produced at the lower O2 flow ratio. High working pressure (2 Pa) gave rise to low quality, low transparency and amorphous films. Under RF sputtering at low vacuum level, the main contribution to the chamber atmosphere is due to water vapor. Oxygen originating from water vapor dissociation induced by plasma plays the same role as an oxygen or water vapor flux usually intentionally introduced in the system in order to have good quality films. [ABSTRACT FROM AUTHOR]

Thermal barrier coatings of Al2O3–ZrO2 were prepared by air plasma spraying on the surface of 20G steel. Phase constitution, microstructures and elemental distributions of the coatings were studied by X-ray diffraction, scanning electron microscope and electron probe X-ray microanalysis. The results show that the plasma spray coating mainly consists of α-Al2O3, c-ZrO2, and t-ZrO2. The bond state of the interface between the top layer and bond layer is fine, and the bond layer has a good combination with the substrate. ZrO2 and Al2O3 structures can closely integrate together and form compact top layer system. [ABSTRACT FROM AUTHOR]