XU Xiao-jing, ZHANG Di, SHI Zhong-liang, ZHAO Chang-zheng, Wu Ren-jie. Superplasticity and Deformation Mechanisms of a Cold-rolled SiCp/LY12 Composite[J]. Journal of Materials Engineering, 1999, 0(10): 3-6.
Superplasticity of a cold-rolled SiC particulate (dp=10um) reinforced Ly 12 (SiCp/LY12) composite has been investigated with a particular focus on superplastic deformation mechanisms. The following results were obtained:(l) the composite exhibits a strain rate sensitivityvalue (m) of about 0.49 and a maximum total elongation of 240% at an initial strain rate of 4.8×10-4 s-1 and at 803K which is 26 K above the solid temperature of the composite; (2) the composite has a grain size of about 10pm after superplastic deformation. (3) the primary superplasticdeformation mechanism in the composite is grain boundary sliding accommodated by the liquidphase at grain boundaries and the dynamic recovery in matrix but controlled by the interfacialstress relaxation by the interfacial liquid phase and interfacial diffusion flow; (4) the liquid phasepresents at the interfaces and grain boundaries due to partial melting plays a vital role in superplasticity in the composite.
LI Chong-jun, YAN Lian-sheng, SU Hong, CUI Wan-ji. Carbon Cloth Layup ZD-C/C Composite[J]. Journal of Materials Engineering, 1999, 0(10): 7-10.
The ZD preforms of carbon/phenolics (C/P) laminates are made by layup of carbon cloth prepregs, then subjected ic carbonization and densification, the ZD-C/C are manufactured.The deepth changes in Z direction during process are checked and the mechanical and Thermophisi-cal properties are studied. The ZD-C/C shrinks obviously in Z direction in process, the ratio of contraction after carbonization is up to 6.99%; after graphitization is 5.55%. The II-SS, tensile strength and modulus are more than 12.6MPa, 133.7MPa and 58.6GPa respectively; the mean compression strength is 228MPa. The thermal conductivity decreases for graphitized ZD-C/C,but enlarges for non-graphitized C/C with temprature increase. The thermal conductivity, the coefficient of thermal expansion and the plasma ablation ratio are of anistropy in X-Y plane and Z direction for ZD-C/C.
LIN Xi-gang, CHEN Shu-xin, MIAO Jing-wei, WEI Jian-jun. Properties and Application of the Low-Temperature Plasma Multiple Technology Deposition Al2O3 Films[J]. Journal of Materials Engineering, 1999, 0(10): 11-13.
The technology of Al2O3 films on permalloy and other magnetically soft materials wasdeposited by low-temperature plasama multiple technology deposition. Properties of Al2O3 filmsand applications of the insulating films to magnetic head lamination were investigated.
WANG Yong, HAN Tao, LIU Min. Local Brittleness of Weld Heat-Affected Zone of X70 Pipeline Steel[J]. Journal of Materials Engineering, 1999, 0(10): 14-16,20.
The effects of thermal cycles on the low temperature brittleness and impact fracture morphology of pipeline steel X70 were studied with the emphasis on the influence of the second thermal cycles on the properties of coarse crystal zone. The results of experiments show that the low temperature toughness goes down with the peak temperature increasing. The toughness isthe best at peak temperature of 950℃ and the fracture is dimple rupture. At peak temperature of 1200℃ and 1360℃ the toughness is lower than the base metal’s, and the fracture is cleavage. The toughness of the coarse crystal zone is improved at the second peak temperature of 950℃, and the fracture is quasi-cleavage, but at the second peak temperature of 780℃, thefracture is cleavage and there are lots of micro-cracks.
ZHI Min-xue, ZHANG Shao-wei. Investigation of Coarsening and Distribution Law ofγ’Phase in Fe-38Ni-13Co-4.7Nb Superalloy[J]. Journal of Materials Engineering, 1999, 0(10): 17-20.
The coarsening and distribution law of r1 phase in Fe-38Ni-13Co-4.7Nb superalloy hasbeen studied. The results show that the γ’ particle is unstable and apt to coarsening. The mean γ’ phase dimension increases linearly with the cube root of time, with the coarsening rate of 0.10nm3/s and 4.26×10-3 nm3/s at 720℃ and 650℃, respectively. The distribution of γ’ phaseis explained by LSEM law. The activation energy for the growth of γ’ phase is estimated to be242. 15kJ/mol. The reason for the unstableness of γ’ phase is short of Al element.
RUAN Zhong-ci, ZHENG Liang. Cd-Zn Alloy and Its Application to Melting Breaker[J]. Journal of Materials Engineering, 1999, 0(10): 21-22,26.
In this paper, the requirement of 280℃ temperature melting breaker used in fireproof valves have been described. According to the requirements, Cd-(11~15)wt% Zn alloys were investigated. Through examination of microstructure and melting characteristic, the selected Cd-11Zn alloy satisfied lechnical specification and was applied widely.
QI Yu-hong, MA Yong-qing, ZHANG Zhan-ping, HEI Zu-kun. Effect of Aluminum on the Reaction Between Cast Iron and Liquid Zn[J]. Journal of Materials Engineering, 1999, 0(10): 23-26.
After adding A1 into cast iron, structure of compound layer formed by reaction betweencast iron and liquid Zn at 500-600 C consists of bulk δ +Fe-Al phases instead of column δ+Γ phases, and the width of the compound layer increases obviously. The consumption of Fe in castiron is dominated by the difflusional speed of Fe through the compound layer, therefor, the corrosion rate of iron is greatly slowed up. The corrosion rate of iron decreases with the content of Al In iron. The corrosion resistance of the cast iron with 8.1% Al is ten times as high as that of ordinary cast iron.
JIAO Jian, LAN Li-wen. Study on Effect of Metal-complex Accelerant to Dicyanodiamide Curing Epoxy Resin[J]. Journal of Materials Engineering, 1999, 0(10): 27-30.
Three kinds of transition metals salt of acetic acid and imldazole complex were synthesised. With the cooperative effect of poly-hydroxy compound, they were the effect accclerant to dicyanodiamide curing epoxy resin. These systems have lower curing temperature than dicyanodiamide curing epoxy without accelerant, can be cured at moderate temperature, and have good potlife at room temperature. Curing reaction of these three systems containing transition metal complex were investigated with gel propertics and differential scanning calorimetry (DSC). Properties of composites were lested. The results show that the curing systems had good properties andcould be used as matrix of composite.
JIANG Bi-biao, HAO Jian-jun, JIANG Lu-xia, CAI Xing-xian. Preparation and Properties of New Bismaleimide MatrixResins and Glass Cloth Reinforced Laminates[J]. Journal of Materials Engineering, 1999, 0(10): 31-34,39.
New bismaleimide with urethane linkages (BMU-T) has been synthesized by means of Diels-Alder reaction of bisfuranylmethylcarbamatc with 4, 4’-bismaleimidodi-phenylmethane(BMI). By mixing BMU-T with BMI in different ratio, a series of toughened bismaleimlde matrix resins and glass cloth reinforced laminates were prepared. The thermal stability of toughened bismaleimide matrix resins, store stability of toughened bismaleimide matrix resins in actonand ethylene glycol monomethyl ether as mixed solvent and mechanical properties of glass clothreinforced laminates have been investigated. It is proved that bismaleimide with urethane linkageis an effective toughening modification agent for 4, 4’-bismaleimidodiphenylmethane, the toughness modified bismaleimide matrix resins have not only excellent solubility but also moderate thermal stability. Glass cloth reinforced laminates have good mechanical, dielectric and heat resistant properties, the fie-cural strength retention can be above 90% at 15℃.
HE Yi-zhu, GAO Jia-sheng, HUANG Zi-you. Influence of Splash and Continuous Annealing on Strength of Mash Seam Welded SPCC Sheet Steel Joints[J]. Journal of Materials Engineering, 1999, 0(10): 35-39.
The high-speed mash seam welding experiments were conducted on cold rolled SPCC sheet steel with thickness ranges of 0.5 to 1.5mm, followed by simulated continuous annealing treatment on some of the samples. The microstructure and splash morphology was investigated.The tensile strength at room and elevated temperature was tested. The effect of splash and continuos treatment on the joint strength was discussed. The results show that the strength of the as-welded joint is greatly reduced when there is crack resulted from splash or incomplete fusion,in the weld. Joint strength is higher than base metal in recrystallized state, and lower than basemetal in non-recrystallized state.
XU Feng-he, XUE Jian-gao. Experimental Analysis of Fatigue Crack Growth for PMMA[J]. Journal of Materials Engineering, 1999, 0(10): 40-41.
The fatigue crack growth experiments were performed according to the phenomena thatcrack occurred at PMMA in use. It is founded that with water immersion, fatigue crack growth isaccelerated for orientation PMMA and delayed for non-orientation PUMA.
WANG Xiao-zhen, JIN Dong-ming. Study of Modifying the Fretting Test Apparatus with Microcomputer[J]. Journal of Materials Engineering, 1999, 0(10): 42-43,47.
The fretting apparatus with step motor takes advantage of simplicity in structure and easy fabricating. However, in operation the vibration from motor will be transferred to flat, interfering in the contacting stability of electronic probe and then affecting the experimental result of fretting, though the vibration possess small amplitude and difficult to measure. The vibration is monitored with computer to lessen the nagative influence.
ZHANG Xiao-ling, HU Nai-sai, HE Jia-wen. Study on the Methods to Improve the Propertiesof Sputtering Deposited MoS2 Films[J]. Journal of Materials Engineering, 1999, 0(10): 44-47.
In this paper, the factors that affect the lubricating properties of sputtering deposited MoS2 films were summarized, and the composite film techniques and the post-deposition treatment techniques were also discussed.
