ZHU Zi-xin, XU Bin-shi, MA Shi-ning, ZHANG Wei, LIU Wei-min. Friction and Wear Behavior of High Velocity Arc Sprayed Fe-Al/WC Composite Coatings at Elevated Temperature[J]. Journal of Materials Engineering, 2003, 0(8): 3-6.
The friction and wear behavior of FeAl/WC intermetallic coating against Si3N4 under dry sliding from room temperature to 650℃ was investigated using a ball on disc tribotester, and the mechanism of high temperature friction and wear was discussed.The coatings were deposited onto 20g low carbon steel substrates using high velocity arc spraying (HVAS) and cored wires.The results indicate that the friction coefficient of the FeAl/WC composite coating decreased significantly with the increased temperature, and the composite coating exhibited low wear rate in the test temperature range.The reason of the friction coefficient decreasing at elevated temperatures is that protective oxide film formed on the worn surface of FeAl/WC composite coating during sliding wear process, which act as a solid lubricant.The delamination is the predominant wear mechanism of the coatings at elevated temperatures. The Fe3Al and FeAl intermetallics with higher strength and hardness at elevated temperatures in the coating can effectively resist crack initiation, propagation and splat fracture, thus resulting in excellent high temperature wear resistance. The slight increase of wear rate at 650℃ may be caused by oxidation and decarburization of WC hard phase on the surface of composite coating.
LIU Zhi-guo, ZHAO Jin-long. Preparation of ZrC Layers in the Tool Steel Surface by Low Pressure Gas Diffusion and Study on their Properties[J]. Journal of Materials Engineering, 2003, 0(8): 7-9.
ZrC layers in the tool steel surface were formed by low pressure gas diffusion, and their properties were investigated in this paper. The results show that the microhardness, abrasion and corrosion resistance of the tool steels are markedly increased because of ZrC in diffusion layers.
FENG Liang, ZHAO Yong-qing, QU Heng-lei, LI Hui, YANG Hai-ying, ZHU Zhi-shou. Microstructure and Property of Ti-6-22-22S Alloy Dimension Bar[J]. Journal of Materials Engineering, 2003, 0(8): 10-12.
The effect of heat-treatments (6 different heat-treatment conditions) on the microstructures and tensile properties at room temperature of Ti-6-22-22S alloy were investigated. The results indicate that the microstructure of the alloy was fine basket weave after forged. While asforged samples were solution treated at higher temperature or aged at lower temperature in α+β phase field, a complex basket weave microstructure was obtained, which contained an irregular basket weave microstructure with few primary α particles or intergranular α lath. A needle basket weave was gained through the triplex heat-treatment. The suitable heat-treatment should be selected to get a more perfect combination properties.
SUN Ming-yan, CHE Ren-chao, CHEN Qing. Fabrication of Aligned Carbon Nanotube Films and Its Field Emission Properties[J]. Journal of Materials Engineering, 2003, 0(8): 13-16.
With FePc,a process to fabricate well-aligned carbon nanotube films was introduced by pyrolysis on different substrates. SEM and TEM images indicate that the as-grown film consists of well-aligned Multi-walled carbon nanotubes(MWNTs). The influence of parameters(such as reaction temperature)was investigated. The field emission properties of as-grown films on different substrates were measured.
WANG Ying, YU Shui, YU Hong-ying, SUN Dong-bai. Nano-scale Ni-P Alloy Powder Produced by Cavitative Field[J]. Journal of Materials Engineering, 2003, 0(8): 17-19.
Nano-scale Ni-P alloy powder in the solution was produced by means of a homemade electrochemistry system with acvitative field. The electrochemistry system consists of a cavitative generating apparatus based on electric spark technique, reaction container, circulating cooling device and a filter by vacuum. The experimental results indicate that the nano-scale Ni-P alloy powder with the microstructure of amorphous have been obtained in NiSO4 and NaH2PO2 solution upon cavitative field. The powder size of the Ni alloy decreases with increasing energy of cavitative field. The typical powder size of the sample is about 80nm.
ZHU Chen-fu, WEI Yun-he, YU Ping, GUO Xiao-yu, LIU Xiu-yu, WANG Lei-lei, CUI-Wei, ZHANG Chang-qiao. The Comparison of Structure and Composition of Corrosion Product for Galvalume in Different Solutions[J]. Journal of Materials Engineering, 2003, 0(8): 20-22.
The structure and composition of Galvalume in different solutions such as NaCl, Na2SO4 and NaCl+Na2SO4 were studied by electron micro-probe and X-ray diffractometer respectively. The results show that the corrosion product in NaCl solution is mainly crystal compound which is not protective to coating, the corrosion product in Na2SO4 and NaCl+Na2SO4 solution is mainly amorphous which is protective to coating. So the amorphous structure is caused by the existence of SO42-.
GUO Hong-min, LIU Xu-bo, YANG Xiang-jie. Model Framework for Microstructure Evolution Modeling with Cellular Automata[J]. Journal of Materials Engineering, 2003, 0(8): 23-27.
Based on the framework characteristic of cellular automaton model, a model framework named as MicrosCA was developed as a general framework model by extending the classical cellular automata. The present framework described brief ideas through which special cellular automaton model simulating and analyzing complicated microstructure evolution phenomena could be built up, and discussed coupling between micromodel and other analyzing models. MicrosCA was not a concretely practical model, but a scheme. Under the framework, it can be extended as practical instance to fulfill the analysis and investigation of various microstructure evolution problems.
HU Zi-li, XIONG-Ke, WANG Xin-wei. Property Evaluation of NiTi Shape Memory Alloy[J]. Journal of Materials Engineering, 2003, 0(8): 28-32.
The important relationships among stress, strain, temperature, electrical resistance and phase transformation of NiTi shape memory alloy (SMA) was synthetically tested and analyzed by various combinations of parameters. A physical model was established to describe the experimental stressstrain curves of SMA, and numerical simulations were performed. Several testing methods were proposed for the need of material evaluations and smart structure developments. Experimental results show that a series of unusual changes on physical and mechanical properties of SMA occur when martensitic, especially R(rhombohedral), phase transformation emerge, and that the constitutive relationship of SMA is highly non-linear. Numerical results are in good agreement with experimental dataIt is an important and effective method to measure stress, strain, electrical resistance and temperature synthetically for studying properties and structural variations of SMA.
HE Fang-cheng, GONG Zhao-bin. Ultrasonic Velocity Measuring Technology and its Application in Materials Evaluation[J]. Journal of Materials Engineering, 2003, 0(8): 33-34.
Two ultrasonic velocity measuring methods were introduced, the principle and difference between the two methods were expatiated. Some examples of ultrasonic velocity measuring technology in material evaluation were given.
FENG Quan, HUANG Xin-yue, TAN Wei-dong, ZHAO Di, WANG Xin-zeng. A Computer Digital System for Temperature Control of Creep Test[J]. Journal of Materials Engineering, 2003, 0(8): 35-36.
A computer digital system for temperature control of creep test was described. It is a research work for the automation of creep test. The emphasis is focused on the designation and mechanism of this system. A 500 hours proved test was successed by this system and the designed functions were tested.
ZHOU Xiao-hu, MA Wen-ge, YU Han-qing, ZHU Zhi-shou. Thermo-mechanical Processing Parameters of TB8 Super-high Strength Titanium Alloy[J]. Journal of Materials Engineering, 2003, 0(8): 37-39,48.
The effect of forging processing parameters such as forging temperature, deformation and post-forging cooling rate on microstructure and mechanical properties of TB8 titanihm alloy was studied. The results show that, after β forging by 30% to 65% at Tβ+20℃ and by post-forging air cooling way, optimum mechanical properties can be obtained with proper heat treatment processing.
LI Dong-mei, CHEN Jing-jing, LI Hui, PAN Feng. Research on Materials of High Frequency Surface Acoustic Wave and Preparation of its Devices[J]. Journal of Materials Engineering, 2003, 0(8): 40-42,36.
The effects of the DC magnetron reactive sputtering technique and the electron beam vapour deposition technique on surface morphology, microstructures of the Al thin films deposited on LiNbO3 substrate were investigated. The 920MHz surface acoustic wave (SAW) filter that use the longitudinally coupled transducers had been fabricated on LiNbO3 substrate using electron beam direct writing and dry etching processes. These results show that electron beam vapour deposition technique can obtain the Al thin films with satisfied properties in the preparation of SAW filters because high binding force between LiNbO3 substrate and Al thin films.
ZHANG Yi, XU Jia-rui. Studies on Microfiber Reinforced Molecular Composites: Concept of Molecular Composites and its Academic Foundations[J]. Journal of Materials Engineering, 2003, 0(8): 43-48.
Microfiber reinforced molecular composites is now playing a more and more importance role in polymer science for its attracted potential industry applications. In this paper, the concept of molecular composites and its academic foundations are reviewed.
