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31.
利用先进的Gleeble-2000热模拟试验机,对GCr15轴承钢某一轧制过程进行模拟试验,测定出GCr15轴承钢动态CCT曲线,并结合微观组织分析,制定合理的GCr15轴承钢轧后控制冷却工艺,以期达到提高GCr15轴承钢质量的最终目的。 相似文献
32.
从退火态原位TiCp/Fe复合材料的切削力和切屑形状方面分析了其切削性能。研究结果表明其切削力及切削力的波动范围都小于铸态45钢,其切削性能比45钢好。TiCp/Fe复合材料的切屑为C形屑、长紧卷屑和发条状卷屑,在机加工中,产生这几种切屑是比较理想的。从切屑方面看,TiCp/Fe复合材料的切削性能较好。 相似文献
33.
Single-crystalline 3C-SiC nanowires have been synthesized in large scale through a one-step autoclave route by the reaction of SiCl4, (C5H5)2Fe and metallic Na at 500 °C. Electron microscopy investigations show that the nanowires have typical diameters of 15-50 nm, lengths up to several tens of micrometers and grow along the [111] direction. The possible growth mechanism of the nanowires is discussed. 相似文献
34.
Effects of austenitizing treatment temperatures on aqueous corrosion properties of martensitic stainless steels were investigated by electrochemical tests (potentiodynamic test, potentiostatic test and electrochemical impedance spectroscopy), and surface analyses (optical microscopy and XRD). The results of potentiodynamic test revealed that the breakdown potential increased with the increased austenitizing temperature, indicating increased relative resistance to initiation of localized corrosion. EIS measurements showed that MSS3 (1030 °C) exhibits larger polarization resistance value than MSS1 (970 °C) and MSS2 (1000 °C) at passive and breakdown states. This was caused by decreasing the amount of Cr-rich M23C6 carbide which acts as preferential sites for pitting corrosion. 相似文献
35.
36.
Kenzo Kitayama 《Journal of the American Ceramic Society》1992,75(6):1447-1451
Phase equilibria in the Ta-Co-O and Nb-Co-O systems have been studied at 1200°C at oxygen partial pressures from 10−0.68 to 10−13.50 atm for the former and from 10−0.68 to 10−13.30 atm for the latter. In both systems, M2 CoO6 and M2 Co4 O9 are stable ternary compounds under the experimental conditions, and a new phase, Nb5 Co2 O14 , has been identified. The Ta-Co-O system is simple, whereas the Nb-Co-O system is somewhat more complicated because of the extra phase. The lattice constants of the ternary compounds have been determined and compared with previous values. The standard Gibbs energies of reactions have been determined using oxygen partial pressures in equilibrium with three solid phases. 相似文献
37.
38.
Evaluation of Slow Crack Growth Resistance in Ceramics for High-Temperature Applications 总被引:1,自引:0,他引:1
The slow (subcritical) crack growth (SCG) resistance of Si3 N4 and SiC ceramics has been evaluated by a stepwise loading test on bending bars precracked by Vickers indentation. Three highly refractory materials were selected for the evaluation: i.e., (1) high-purity Si3 N4 sintered by hot isostatic pressing (HIP) without additives and (2,3) α - and β - SiC pressureless sintered with B and C addition. Under the hypothesis of linear elastic behavior at high temperature, which was found satisfied in the present materials, the SCG resistance was expressed in terms of initial stress intensity factor critical for SCG failure within a predetermined lifetime. The present method was found useful in shortening the testing time and consistent with other traditional fatigue tests (e.g., static-fatigue test): It is recommended as a screening test for materials under research and development. Among the materials tested in the present study, the highest SCG resistance up to 1440°C was found in the high-purity Si3 N4 without additives. 相似文献
39.
Satohiro Yoshida Tsunehiro Tanaka Tomoko Hanada Takeshi Hiraiwa Hiroyoshi Kanai Takuzo Funabiki 《Catalysis Letters》1992,12(1-3):277-285
XANES of vanadium and niobium oxide on silica or alumina have been analyzed quantitatively by a deconvolution technique. Based on the results for reference compounds, local structures of supported vanadium and niobium species were identified. The composition was estimated from difference spectra for the samples which consisted of two kinds of species. 相似文献
40.
用50W连续波CO_2激光器为热源,诱发SiH_4和C_2H_4反应,合成SiC超细粉末。实验确定了反应腔体内压力p、气源中的C/Si原子比、喷嘴内径2r以及激光功率密度与粉末特性之间的关系,并对合成的产物进行物理、化学表征。 相似文献