LIU Qian, LI Jia-lu, LI Xue-ming. Research of Bending and Compression Properties of 3-d Braided Composite Materials[J]. Journal of Materials Engineering, 2000, 0(8): 3-6.
The bending and compression experiments have been done for the 4-step 3-d braided composites. Their principal mechanical properties, deformational characteristics and destroy ruler are obtained. The results show that the 3-d braided composites have good behavior, and the braid structures have a great influence on it. These results can provide an experimental basis for further studies on failure problems of braided composites.
LUO Ruiying. A Study of Oxidation and Protection Properties From Oxidation for Carbon/Carbon Composite[J]. Journal of Materials Engineering, 2000, 0(8): 7-10.
Carbon/carbon (C/C)composite whose density is 1.77g/cm3 was prepared after the preforms were deposited in 210 hours by new technology of rapid chemical vapor deposition,and their oxidation dynamics was studied .The results show that the initial oxidizing temperature of C/C composite is up to 672℃,the Arrhenius curve is composed by two straight line at linear oxidation st age (the transition temperature is 700℃),and the value of activation energy is 80 and 121kJ/mol at different oxidation stage respectively. The oxidizing process has been dynamically observed by SEM. It is found that the oxidation begins with the original pores on C/C composite surface,the carbon fiber and matrix are oxidized simultaneously,and the residue of oxidizing is noeven and porous deposited carbon which is distributed about carbon fiber. The coating of protection C/C composite from oxidizing was developed. The cost of this kind coating is low,and brushing technology is simple, The experiment after oxidizing at 900℃ and thermal shock testified that the coating has better effect of oxidation-resistant. The mechanism of oxidation-resistant on coating is discussed.
SUN Yong-xing, WANG Yin-zhen, HE Yan-ling, ZHENG Xiu-lin. The Effects of Additive on Thermal Shock Life of Cr2O3 Coating and the Choice of Coating[J]. Journal of Materials Engineering, 2000, 0(8): 11-14.
The influence of additive CeO2 and SiO2 with different content on the thermal shock failure life of Cr2O3 coating was studied. It is shown that the thermal shock failure mechanism of coating is thermal stress fatigue destruction through thermal shock text. The critical temperature range △TC can be greatly enhanced by adding CeO2 and SiO2 to Cr2O3 layer through reanalysis the results of thermal shock experiment date. The addition of proper amount of CeO2 to Cr2O3 layer obviously increase the coefficient of coating’s resistance to thermal shock, but proper amount of SiO2 to Cr2O3 layer greatly increase △TC. The choosing additive is based on the serve condition of coating. When coating works at temperature being lower 300℃,the adding 3.0% CeO2 to Ce2O3 layer is chosen because which has the best complex property. But, when coating works between 300℃ and 500℃, the SiO2 is chosen as additive to Cr2O3 layer, which has longer thermal shock lifetime.
WANG Ji-gang, GUO Quan-gui, LIU Lang, SONG Jin-ren. Adhesive Shear Strength and Electrical Conductivity of Graphite Bonded by Adhesives of Phenol-formaldehyde Resin Modified by Silicon[J]. Journal of Materials Engineering, 2000, 0(8): 15-17.
High temperature adhesives were prepared using Phenol-Formaldehyde Resin as matrix and silicon powders as additives to modify the properties of the adhesives. The samples of graphite bonded by the above adhesives were heat-treated at different temperatures ranged from 200℃ to 1500℃. Subsequently their adhesive shear strength and electrical conductivity were tested. Results showed that bonded graphite samples heat-treated at 200℃ have high electrical resistivity and their fracture mode is due to failure of graphite, but not the adhesion interface. The samples treated at 800℃ demonstrated good adhesion between the adhesives and graphite, while their electrical conductivity decreased markedly compared with that at 200℃. With the heating temperatures rising to 1500℃ further, adhesive shear strength and electrical conductivity of the bonded samples decreased drastically. The relationship between the composition, structure of the adhesives and the adhesive shear strength and electrical conductivity of the bonded samples were also discussed in this paper.
LI De-zhan, LI Yin-kui, ZHANG HONG ping, LONG Yong-fu. A Study of the Carbon Fiber Coated Continually with B4C by CVD Method[J]. Journal of Materials Engineering, 2000, 0(8): 18-20,38.
Using H2,CH4,BCl3 as raw materials,carbon fibers were coated with B4C by CVD method. The best coating condition like BCl3/CH4=3/5,H2 excessive,deposition temperature(1150℃)and fiber walking speed(1m/min) was got by the discussion of several influential factors such as the temperature,the ratios of reaction gases and fiber walking speed. Comparing the TG DTA,the SEM and the straining strength of coated fibers and raw fibers,we can find that the properties of coated fiber is improved.
HUANG Chuan-yong, TANG Zi-long, ZHANG Zhong-tai, JIN Miao, CHEN Qing-ming. The Process and Properties of Nanometer Zirconia Powder by Environmental Benign Method[J]. Journal of Materials Engineering, 2000, 0(8): 21-24.
Nanometer zirconia powder was prepared by the environmental benign method and the properties of ultrafine zirconia were studied with aids of XRF, XRD, TEM, particle size analysis, etc. The experiments show that the method has great accommodation and the powders have high purity, activity and less chlorion. The cause was also investigated in the paper. In the powder the main phase is t/c zirconia and no monoclinic zirconia is found. Compared with the particle size of powder (about 7nm), the agglomerate is narrowly distributed at about 1μm and is crushed under the pressure of nearly 250MPa. The coexisting critical size of m and t/c phase is 12.6nm.
WANG Ying-chun, MA Zhuang, LÜ Guang-shu, WANG Quan-sheng. Study On Wearing Resistance of Electroless Ni-P Alloy[J]. Journal of Materials Engineering, 2000, 0(8): 25-27.
The wear resistance tests of electroless Ni-P coating which was treated at several different temperatures were studied, and the wear resistance mechanism of E-Ni-P coating was discussed. The results indicate that the hardness of Ni-P coating is the highest with 400℃ heat treatment,and the best effect of wear resistance is 600℃ heat treatment.
KOU Kai-chang, YANG Yan-qing, CHEN Yan, KANG Mo-kuang. Self-propagating High-temperature Combustion Synthesis of [Mo(1-x),Wx]Si2/[Mo(1-x),Wx]5Si3[J]. Journal of Materials Engineering, 2000, 0(8): 28-30.
According to thermodynamic consideration, it is possible that, during alloying MoSi2 with WSi2, Mo5Si3-W5Si3 particles can be introduced in the [Mo(1-x),Wx]Si2 powder by the method of self propagating high temperature combustion synthesis.[Mo0.87,W0.13]Si2/[Mo0.87,W0.13]5Si3 composite powder was synthesized by the method. It was confirmed that Mo5Si3-W5Si3 exists in a form of solid solution of [Mo(1-x),Wx]5Si3.
YANG Lian-he, WANG Rui. Composite Measurement of Elasticity Constants of Brittle Materials and its Programming Realization[J]. Journal of Materials Engineering, 2000, 0(8): 31-33.
The paper points out the difficulty brought by determining directly the elasticity constants of brittle materials, presents the composite measurement and describes the procedure of the data processing. A new method is found which is more precise for measuring the elasticity constants The C program is worked out based on the method.
CAI Bo-cheng, LIU Pei-ying, TAO Ye, ZHANG Shao-yong. The Isothermal Oxidation Behavior of Ti60 Alloy at Elevated Temperature[J]. Journal of Materials Engineering, 2000, 0(8): 34-36.
The isothermal oxidation behavior of Ti60 alloy (Ti-5.6Al-4.8Sn-2.0Zr-1.0Mo-0.85Nd-0.34Si)at 620℃, 720℃, 800℃ in air environment was investigated in this paper. The mass gain was measured and the oxidation kinetics curves were determined SEM, XRD and EDS were used to study the microstructure, composition and morphology of the oxidized layer. It has been showed that at 620℃, the oxidation kinetics can be described by parabolic law and the oxidation kinetics curves,at 720℃ and 800℃, have linear character.
ZHAO Ping, GAO Sheng-ji, SHEN Bao-luo, TU Ming-jing. Oxide Film in Interface between Matrix and Fibre in Mullite Short-fibre Reinforced ZL109 Composite[J]. Journal of Materials Engineering, 2000, 0(8): 37-38.
The existing of the oxide film in the interface between the fibre and matrix in the mullite short fibre reinforced ZL109 composite has been proved by TEM, and it has also been showed by TEM that the crystal structure of the oxide film is gama-Al2O3.
WANG Er-min, WANG Xiao-zhen, ZHAO Xin-qing. The Effect of Ion Implantation on the Characteristics of Oxide Formation of Copper Thin Films[J]. Journal of Materials Engineering, 2000, 0(8): 39-40,46.
Using X-ray diffraction and Rutherford back-scattering techniques, a study has been made of the oxidation characteristics of copper thin films by Cr ion implantation. It is indicated that the implantation of Cr ions remarkably changes the oxidation behavior and the copper oxide structures Ion implantation suppresses the diffusion of copper atoms during oxidation and then inhibits the change of Cu2O to CuO The formation mechanism of oxides before and after implantation was discussed.
ZHANG Wen-long, YAN Jia-chao, WANG De-zun, YAO Zhong-kai, GU Ming-yuan. Clad-extrusion of SiCW/LD2 Composite[J]. Journal of Materials Engineering, 2000, 0(8): 41-42,24.
The extrusion technologies of SiCW/LD2 composite were investigated. The results indicate that there are the serious defects on the outer surface of SiCW/LD2 composite tubes made using a conventional hot-extrusion method. The outer surface of SiCW/LD2 composite tubes is clad by a layer of aluminum when a clad extrusion method is used. Therefore, the clad-extrusion is an effective method for hot extruding SiCW/Al composites into tubes.
TANG Jing-lin, ZENG Da-ben. Influence of Microstructure of Semi-solid A356 Alloy on its Transient Rheological Behavior[J]. Journal of Materials Engineering, 2000, 0(8): 43-46.
Transient rheological behavior of semi-solid A356 alloy was explored through the use of rest time experiment by a self-designed rheometer. The morphology of primary α phases was respectively dendrite, rosette and spheroid. In the rest time experiments, abrupt shear resulted in peak viscosity which then drifted to an equilibrium or steady state with constant shearing. The apparent viscosity evidently decreased along with the microstructure transforming from dendrite to spheroid. Regression analysis was adopted to study the variation of apparent viscosity of semi solid alloy in the isothermal constant shear process. Results indicated that semi-solid A356 alloys fit the power law model in rest time experiments. After abrupt shear, It would take much longer time for dendritic SSM to reduce viscosity to an equilibrium or steady state than that for semi-solid alloys with spheroid and rosette.
HONG Run-zhou. Research for Foundry Process of Complicate Thin-Wall Aluminum Alloy Castings[J]. Journal of Materials Engineering, 2000, 0(8): 47-48,10.
This paper studied a complicate,thin-wall aluminium alloy casting,according to the solution of the numerical simulation of foundry process,the best parameter and process of pouring had been studied out.With the technique of vacuum suction and solidification under pressure,the casting was shaped with high metallurgical quality conforming to the standard′s demand.
