XU Wei-pu, XU Bin-shi, ZHANG Wei, WU Yi-xiong. High Temperature Properties Research of High Velocity Arc Sprayed Fe-Al/Cr3C2 Coatings[J]. Journal of Materials Engineering, 2004, 0(11): 3-6,10.
High temperature wear, erosion and corrosion properties of Fe-Al/Cr3C2 coatings that in-situ synthesized by cored wire and high velocity arc spraying (HVAS) were investigated. The results show that, coatings improve high temperature erosion properties of the substrate, the erosion properties of coatings increase with the increase of temperature and angle. As the exists of Cr2O3 and high bond energy of coatings, its high temperature corrosion properties of coatings is good. Coatings have excellent room temperature wear resistance because of the rich of Cat wear place, it also has good high temperature wear resistance.
LI Jin-ping, MENG Song-he, HAN Jie-cai, LUO Shou-jing. Effect of Post-sintering Treatment on Microstructure of Explosively Compacted CuCr Alloys[J]. Journal of Materials Engineering, 2004, 0(11): 7-10.
Two kinds of post-sintering processes were used for explosively compacted CuCr alloys, and mi-crostructure change before and after sintering was observed, so as to study on effect of post-sintering on microstructure of explosively compacted CuCr alloys. The results showed that, the microstructure of CuCr alloys showed liquid-sintering characters after hydrogen sintering, the microstructure of CuCr alloys showed solid-sintering characters after vacuum sintering and their structure after sintering treatment was finer than that of explosively compacted CuCr alloys. After explosively compacted CuCr alloys were post-sintered, CuCr alloys still were composed of Cu phase, Cr phase and small amount of oxides. Besides, compound separation appeared at lower degree in micro-area, and there were many strain stripes and dislocations in the sintered CuCr alloys.
LI Ping, WANG Han-gong. Study of Slide Wear Resistance Properties of Coatings Ti-Al Twin Wires Ultrasonic Arc Sprayed[J]. Journal of Materials Engineering, 2004, 0(11): 11-14,17.
In order to strengthen the wear resistance in surface of aluminum alloy (LY12), coatings were manufactured by using titanium and aluminum wires and supersonic arc spraying systems of model SAS-I. The influence of arc spraying technological parameters on oil drip feed lubrication slide-wear resistance of coatings was studied by orthogonal regression experimental design method, then the slide wear properties of the coatings sprayed under optimum parameters conditions and the aluminum alloy matrix (LY12) was determined, the microstructure of the coatings and the character of worn surface were observed and analyzed by X-ray diffraction and scanning electric microscopy respectively. The results show that; the abrasive volume of coatings decreases with spraying voltage while the spraying distance is shorter, and increases with spraying voltage at the longer spraying distance, the longer the spraying distance, the higher the speed of coating abrasive volume increasing with spraying voltage; the abrasive volume of coatings decreases with spraying distance at lower spraying voltage, but with spraying voltage increasing, the volume of coatings increases with spraying distance and the more quickly the abrasive volume of coatings increasing with spraying distance. The abrasive volume of coatings sprayed by optimum parameters, such as 26V and 0.236m, is only equal to 1/38.84 of aluminum alloy (LY12). It is indicated that the coatings of Ti-Al twin wires ultrasonic arc spraying has excellent surface strengthening effect on aluminum alloy with optimum spraying parameters.
HONG Quan, ZHAO Yong-qing, YANG Guan-jun, ZENG Wei-dong. Effects of Pack Ply-rolling Process on Microstructure and Mechanical Properties of Ti-6Al-4V Alloy Sheets[J]. Journal of Materials Engineering, 2004, 0(11): 15-17.
The influence of pack ply-rolling process and heat-treatment on the microstructure, tensile properties and fatigue properties of Ti-6Al-4V alloy sheets was studied . The results show that the unidirectional rolling process condition has higher elongation and lower fatigue strength. The sheets in cross rolling process possess good comprehensive properties.
CAO Zhong-qiu, NIU Yan, WANG Chong-lin, WU Wei-tao. Study of Preparation and Microstructure of Cu40Ni40Cr20 Alloys with Different Grain Size[J]. Journal of Materials Engineering, 2004, 0(11): 18-21,27.
The Cu40Ni40Cr20 bulk alloys with much different grain size have been prepared respectively by conventional arc-melting (CA) and mechanical alloying (MA) . Their micro-structural characteristics were investigated by X-ray diffraction (XDR), scanning electron microscopy(SEM) and energy-dispersive X-ray microanalysis (EDX). The results show that the microstructure of CA Cu40Ni40Cr20 is composed of double phases but extremely not uniform, while that of MA Cu40Ni40Cr20 is also composed of double phases but uniform with excellent density. With increase of ball milling time, the X-ray diffraction peaks have a deviation and become wide because of fine grain size and internal stress whereas the solid solubility of Cu in Cr and Cr in Cu increased evidently. When powders are milled for 60h, the alloyed powers have become single solid solution. Because the mechanically alloyed powders are in non-equilibrium state, the solute super-saturation decompose slowly with hot pressing and annealing in vacuum and finally the alloys transformed double-phases from single phase solid solution. The sizes of the two phases particles increased but still remained nano-size range. The lattices of copper, nickel and chromium do not produce distortion in the course of mechanical alloying, hot pressing mechanically alloyed powders and annealing. The effect of grain size on alloys microstructure was discussed in detail.
HUANG Tai-wen, LIU Lin, YANG Ai-min, XIONG Yu-hua, ZHAO Zhi-long. Effect of Structure Refinement by Addition of Refiner on LCF Properties of Cast Superalloy K4169[J]. Journal of Materials Engineering, 2004, 0(11): 22-27.
The ingots of cast superalloy K4169 was refined with the addition of a trace of intermetallic compounds to the melt under conventional casting condition. The low cycle fatigue(LCF) properties were tested both for normal and refined test bars. The results show that the grains can be refined to ASTM 1.7. As a result, LCF life of refined test bars is 1.2-2 times compared to that of normal ones at room temperature. As a contrast, LCF properties at 700℃ are different, depending on the total strain amplitude. LCF life for refined samples are superior than coarse ones at small total strain amplitude, and inferior at high total strain amplitude. Fatigue data fluctuation is improved of fined grains at all conditions.
ZHANG De-fen, HUANG Tao, HU Zhuo-chao, ZUO Liang, WANG Fu. Study of Recrystallization Texture of Aluminium Alloy 3104[J]. Journal of Materials Engineering, 2004, 0(11): 28-31,36.
The recrystallization textures after different annealing processes of 3104 aluminium alloy had been investigated by means of orientation distribution functions(ODFs) .The results show that the deformation textures are composed of C{112}<111>,B{110}<112>and S{123} <634>components. Annealing temperature and retaining time have notable effects on recrystallization textures.The intensity of cube texture is weak at low temperature for short time, but with temperature and retaining time increasing, the intensity of cube texture is increased. Recrystallization is finished after annealed at 350℃ for 60min, 400℃ for 60min and 450℃ for 15min, the intensity of cube texture is the strongest about 10 grade at 400℃ for 60min and there are a little weak cold textures. With annealing temperature increasing, diffuse precipitated phases Al6(Fe,Mn) and Al(Fe,Mn) act on particle stimulate nucleation during process of re-crystallization .
GUO Shi-bo, QU Xuan-hui, DUAN Bo-hua, HE Xin-bo, QIN Ming-li. Optimization of Titanium Alloy Injection Molding Process Parameters[J]. Journal of Materials Engineering, 2004, 0(11): 32-36.
Effects of process parameters such as injection pressure, injection speed, injection temperature, die temperature and their interaction, on the density and strength of the as-molded specimens were systematically studied by using orthogonal arrays design and statistical analysis method. The notability of process parameters was estimated and process parameters were optimized. Results indicated that injection pressure, injection temperature and their interaction had remarkable effect on strength, however, injection pressure, injection temperature, injection speed and interaction of injection pressure and die temperature, had distinguished influence on density. The density and strength increased as injection pressure increased. The density decreased as injection temperature increased, but the strength nearly keep constant at 155-160℃,then decreased sharply beyond 160℃.The density and strength reached the best values when die temperature and injection speed are 30℃ and 60% respectively. The optimized injection parameters for rectangular with a dimension of 6.38mm × 6.38mm × 48mm are as followings: injection pressure 100MPa,injection temperature 155℃,injection speed 60% and die temperature 30℃.
LIU Guo-yu, BAO Chong-gao, ZHANG An-feng. Study on Erosion-corrosion Property of Metal Material[J]. Journal of Materials Engineering, 2004, 0(11): 37-40.
The two-phase flow of liquid and solid erosion-corrosion tester was used to simulate different erosion-corrosion conditions. The erosion-corrosion behavior of 1Cr18Ni9Ti and T8 was studied. The damage of material was accelerated as increasing erosion speed and slurry temperature. The erosion-corrosion mass loss rate of T8 was much higher than that of 1Cr18Ni9Ti. In order to increase the resistance of the erosion-corrosion of material in acid slurry, first, the materials must have good corrosion resistance, and the second, they must have good wear resistance. The erosion-corrosion mass loss rates of 18-8 and T8 appears maximum value, when the erosion angle is at 45 degree, so that the erosion angle of 45 degree in the pipeline structure should be avoided.
LI Xiong, ZHANG Hong-bing, RUAN Xue-yu, LUO Zhong-hua, ZHANG Yan. Analysis and Modeling of Flow Stress of 40Cr Steel[J]. Journal of Materials Engineering, 2004, 0(11): 41-44,49.
The flow stresses at various deformation conditions were studied. The results show that flow stress decreases with deformation temperature increasing, and increases with strain rate increasing. Based on Ludwik-Hollomon model, an improved model suiting for hot and warm working was discussed. A good result was got when modeling flow stress of 40Cr steel in the improved model. Hardening exponent n is insensitive to deformation temperature. At low strain rate, n value is hardly changed; when up to a high strain rate, n jumps to a high value. By simplifying some parameters, peak stress can be predicted. The average relative error and the mean square root between predicted and experimental flow stresses are 7.7% and 17.59MPa, respectively.
YAN Shi-jian, TIAN Wen-huai. Preparing TEM Thin Foil by Composite Electroplating[J]. Journal of Materials Engineering, 2004, 0(11): 45-49.
A convenient and practical technique to prepare TEM thin foil containing particles have been presented. First, particles were entrapped into copper electroplating coat by composite electroplating. Second, the composite coating was thinned by twin-jet electropolishing or ion-thinning, then the particles in it were thinned simultaneousely. In this study nonconducting LiCoO2 and conducting WC were entrapped. Select proper current density to obtain composite coating in which the particles were as many as possible and were entrapped tightly. Select proper pH-value of electrolyte to obtain composite coating which had moderate brittleness. Select proper stirring velocity to entrap smaller particles into composite coating.
REN Si-yu, WANG Ying-lian, SUN Wang-dian, LIU Yu-hua. Characteristic Comparison of ZnO Thin Film Prepared by Sol-gel Method and R.F. Magnetron Sputtering[J]. Journal of Materials Engineering, 2004, 0(11): 50-52,56.
ZnO thin films were successfully fabricated by sol-gel method and R.F. Magnetron Sputtering on quartz glass substrates. The preparing details were thoroughly introduced. X-ray Diffractometer (XRD), Atomic Force Microscope (AFM) , Raman Scattering Spectroscope (RAMAN), UV-Vis Absorp-tion(UV-Vis) were used to carried out specific studies and comparisons of their specialties. The results show that, coated on same substrates, annealed at same temperature, the films prepared by magnetron sputtering show much more prominent c-axis orientation and excellent crystallinity than those prepared by sol-gel.
LI Shang-ping, LUO He-li, FENG Di, CAO Xu, ZHANG Xi-e. Influence of Carbides Characters on Microstructure and Properties of Ni3Al Base Surface-strengthening Composites[J]. Journal of Materials Engineering, 2004, 0(11): 53-56.
Two welding wires including Cr3C2-Ni-Al and WC-Ni-Al were produced by pressureless sintering in vacuum. When the welding wires were welded on the surface of carbon steel by the manual gas-tungsten arc welding, carbide particles reinforced Ni3Al base composites were formed by the physical heat of arc and Ni-Al exothermic reaction. XRD showed that Ni reacted with Al to form Ni3Al in both wires during welding. Microstructure and hardness tests showed that carbides distributed in matrix and strengthened matrix differently, which was mainly attributed to their different physical characters (such as density, melting point). WC appeared as large particles and segregated on welding interfaces, and hence the strengthening effect was small. However, Cr3C2 was decomposed during welding to form the dispersed Cr7C3 with stripe shape, which strengthened the matrix significantly. The room and high temperature hardness of Cr7C3/ Ni3Al composite was much higher than that of Stellite alloys. Cr7C3/Ni3Al composite is attractive as potential candidate for high-temperature surface wear-resistant material.
TAN Qiang-qiang, TANG Zi-long, ZHANG Zhong-tai. Preparation and Microstructure of Nanometer Tetragonal Polycrystal Zirconia Powder at Low Temperature Condition[J]. Journal of Materials Engineering, 2004, 0(11): 57-60.
Nanometer tetragonal polycrystal zirconia powder was prepared by the milling method in the super-alkaline medium containing organic addition. The properties and the microstructures of zirconia nanometer particles were investigated by X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), transmission electron microscopy (TEM). The results show that the zirconia nuclei are synthesized in the beginning of the reaction between zirconium oxy-chloride and sodium hydroxide. It is obviously different from the others about preparing methods of zirconia powders. Simultaneity the nanomerter tetragonal polycrystal zirconia powders are obtained with the perfect properties including high purity and less chlorine, smaller and even particle size, excellent dispersing property due to addition of the polymer. The organic addition-assisted super-alkaline method has the advantages of low synthesizing temperature and saving resources and high efficiency relative to other methods.
WANG Juan, LIANG Tong-xiang, LI Chen-sha. Preparation Technologies of Monodisperse Polymer Microspheres[J]. Journal of Materials Engineering, 2004, 0(11): 61-64.
The progress of different synthesis methods of monodisperse microspheres are reviewed. Especially, some special preparation technologies, including shirasu porous glass-suspension polymerization, microwave or ionizing radiation-induced polymerization and photopolymerization reactions in aresols, are introduced. And the first-three kinds of methods polluted environment lightly, they can help industrial production of monodisperse polymer microspheres environmentally-friendly.
