BI Gang, WANG Haowei, WU Renjie, ZHANG Di. Nitridation Characteristics of Aluminum Borate Whisker[J]. Journal of Materials Engineering, 2000, 0(7): 3-6,9.
Aimed to overcome the serious interfacial reaction of aluminum borate whisker reinforced aluminum alloy composites, the nitridation process of the aluminum borate whisker was put out first time based on the thermodynamic calculation. By means of the X-ray photoelectron spectroscopy(XPS) analysis, the nitridation characters of the whisker were studied. The experimental results show that the nitrogen element can react with the whisker and the boron in the aluminum borate whisker transforms into the boron nitride compound. The nitridation, which is controlled by the diffusion, is a thermally activated process, the activation energy Ea=30634kJ/mol.
HOU Xianghui, LI Hejun, SHEN Jian, WANG Can, ZHU Zhengang. Research on Internal Friction Behavior in Carbon/Carbon Composites[J]. Journal of Materials Engineering, 2000, 0(7): 6-9.
The internal friction behaviors in carbon-carbo composites are the results of combination effects of various structural factors in materials. The present work mainly focused on the effects of pyrolytic carbon matrix, carbon fibers and interface on the whole internal friction of carboncarbon composites respectively According to experimental results, the characters of internal friction in carbon-carbon composites were discussed.
XIANG Yibin, CHEN Dunjun, WU Shichun. Toughening Mechanics Mechanism and Toughening Design for Material Interfaces[J]. Journal of Materials Engineering, 2000, 0(7): 10-12.
Based on the interfacial fracture mechanics, this paper presents the principal toughening mechanics mechanism for the material interfaces using interfacial fracture energy and mixture mode as primary microstructural parameters:one is to improve interfacial fracture toughness, the other is to realize optimum fracture path. And according to the toughening mechanism the main principles and methods in toughening design of material interfaces are studied, which provides theory basis for the actual interface design.
HUANG Chuanyong, TANG Zilong, ZHANG Zhongtai, JIN Miao, SONG Chaozhong. Gel-Tape Casting of Yttria Stabilized Zirconia Thin Film[J]. Journal of Materials Engineering, 2000, 0(7): 13-16.
A new method of tape casting was modified with the advantages of gelation. A thin solid electrolyte film of yttria stabilized zirconia with high density, less porosity was fabricated by this method with 54vol% solid content slurry. The character of the process was discussed based on the aspects of powder, influence of disperant and pH on slurry, density of green body and sintered materials. The experiments show that compared with pressing and tape casting, gel-tape casting can fabricate thin film with high density and homogenous structure. The method is suitable for preparing thin electrolyte film of yttria stabilized zirconia.
WAN Yizao, WANG Yulin, ZHOU Fugang, ZHAO Qiang, QI Jingang, WANG Qin. Effect of Fiber Surface Treatment on Interfacial Bonding Strength of C/PLA Composites(Ⅱ)[J]. Journal of Materials Engineering, 2000, 0(7): 17-19,23.
Interfacial conditions of carbon fiber-reinforced polylactide(C/PLA) composites were investigated. The emphasis was focused on the influence of fiber surface treatment with nitric acid on interfacial bonding strength of the C/PLA composites and the adhesion mechanism. The results showed that the interfacial bonding strength increased greatly, while the impact strength, flexural strength and modulus, and shear strength increased slightly after fiber surface treatment XPS analyses demonstrated that a chemical reaction occurred at fiber-PLA interfaces. The increase in interfacial bonding strength was attributed to the increase in the level of chemical reaction at fiber-PLA interfaces and fiber surface roughness, but the former is dominant.
WANG Xiaoping, ZHENG Yunrong. Discontinuous Coarsening Transformations in TiAl Based Alloys[J]. Journal of Materials Engineering, 2000, 0(7): 20-23.
In order to obtain fine grain microstructure in as-cast TiAl based alloys, three alloys of Ti-44.9Al, Ti-48Al and Ti-44.3Al-3.0Cr(at%) were heat treated at 1150℃(just slightly above the TiAl eutectoid temperature). The results show that there are three typical types of discontinuous coarsening transformations of the Ti3Al+TiAl lamellae in these Ti-Al based alloys and the ascast grain sizes of these TiAl alloys can be refined significantly by the discontinuous coarsening transformations. The best result of refining grains is achieved in Ti-44.3Al-3Cr alloy Moreover, the increase of aluminum content,addition of alloying element Cr can speed up the process of discontinuous coarsening greatly.
JIN Fangwei, LIU Zuoquan. Study on the Structures and Magnetic Properties of Rapidly Solidified Bi-Mn Alloys[J]. Journal of Materials Engineering, 2000, 0(7): 24-26,29.
The six Bi-Mn ribbons with different compositions were prepared by using a vacuum melt-spinning instrument made ourselves A X-ray diffractometer and a vibrating sample magnetometer were used for measuring the phases and magnetic properties of as-quenched and annealed samples. The linear variation equation of saturation magnetization σs and remained magnetization σr with composition(wt%),and the existence of a maximum in a variation of coercive force Hcm with Mn concentration have been obtained. The solubility of Mnin solid Biin as-quenched samples has been deduced to be 24% from the data of magnetic measurement Large quantity of quenched hight-emperature phase(QHTP) were detected in the as-quenched sample of 16wt% Mn.
WANG Jun, CHEN Ge, SONG Yongcai, WANG Yingde, FENG Chunxiang. Designing of Structural Radar Absorbing Materials with Shaped Silicon Carbide Fibers for Absorbent[J]. Journal of Materials Engineering, 2000, 0(7): 27-29.
The structural radar absorbing materials, which composed of shaped silicon carbide fibers with resin, were prepared through designing impedance matching,the materials exhibited a reflection attenuation amount of about 10dB in the range of X-band.
ZHOU Longjie, XU Xingli, HUANG Yong, XIE Zhipeng, DAI Jianqing. Gas-discharging Reactions in Gelcasting of Si-containing Materials and Their Effect on Microstructure of Green Bodies[J]. Journal of Materials Engineering, 2000, 0(7): 30-33,36.
in situ consolidation colloidal forming processes, such as gelcasting, are promising techniques for complex shapes of materials with high density, high uniformity and, thus, high reliability of performance Si-containing powders, e. g. Si, SiC and Si3N4, are suitable for being well dispersed in alkaline solutions However, silicon powder and free silicon contained in silicon carbide and silicon nitride powders have a tendency to hydrolyze, especially in a basic aqueous solution for gelcasting, causing a large amount of macropores in green bodies as a consequence of hydrogen gas evolution Moreover, silicon nitride itself is chemically unstable in aqueous solutions and easy to react with other reagents when processed by aqueous gelcasting, which also affects the microstructure of green bodies After identifying the causes of macropores formation in the gelcast green bodies, some solutions are proposed to overcome these problems.
CHENG Jihong, ZENG Zhaoqiang, WU Chongjun. A Study on Reactive Sintering of TiH2-TiB2[J]. Journal of Materials Engineering, 2000, 0(7): 34-36.
The reactive sintering between TiH2 and TiB2 was studied in this paper, with the in situ formation of the transient phase TiB. With the increase of TiB2 content, TiB2 is transformed to TiB gradually and the sample's porosity increases, density and conductivity decreases. But when TiH2:TiB2 increases to 2:1,all TiB2 is transformed to TiB and both density and conductivity are improved Laminated structure of the transient phase TiB is observed by SEM.
WANG Guisong, GENG Lin, ZHENG Zhenzhu, WANG Dezun, YAO Zhongkai. Effects of Compression Deformation Strain Rates at Temperature in the Solid-Liquid Two-phase Region on the Microstructure and Properties of SiCw/6061Al Composites[J]. Journal of Materials Engineering, 2000, 0(7): 37-39,48.
Effects of compression deformation strain rates at temperature in the solid-liquid two-phase region on the microstructure and properties of SiCw/6061Al composites were investigated It is found that the aspect ratio and orientation of whisker,uniform of composites,interfacial bonding is affected more or less by compression deformation strain rates. The properties of composites are affected by the changes of composite microstructure. The changes of composite properties after large deformation what took place at high temperature are the most important index for evaluating high temperature plastic forming. The best deformation parameter is determined by analyzing the microstructure and the properties of composites.
JIANG Zhaohua, XIN Shigang, WANG Fuping, WU Xiaohong. A Study on the Micro-plasma Oxidation of Aluminum Alloy in Systems(NaPO3)6-NaAlO2[J]. Journal of Materials Engineering, 2000, 0(7): 40-42.
The microplasma oxidation processes of the LY12 aluminum alloy in the solution sodium hexametaphosphite-sodium meta-aluminate, the formation characteristics of the ceramic film, and the effects of sodium meta-aluminate concentration on the oxidation process were studied The phase compositions and morphologies of the film were analyzed by XRD and SEM.
XU Zhongbin, YI Xiaosu, WU Shunying. Progress in Study of Spinning Mechanism and Technique of Special Plastics PEEK[J]. Journal of Materials Engineering, 2000, 0(7): 43-46.
On the basis of literatures, the spinning mechanism and technique of special plastics PEEK are analyzed. The influence factors of PEEK melt spinning process and the key problems of PEEK melt extrusion equipment as well as the solving methods are pointed out. It provides scientific basis for further construction design and processing.
