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991.
992.
993.
大尺寸TiB2-Cu-Ni金属陶瓷块体的燃烧合成及准热等静压致密化 总被引:4,自引:1,他引:4
利用燃烧合成结合准热等静压 (PHIP)技术成功制备了直径为 2 40mm的大尺寸TiB2 Cu Ni金属陶瓷 ,对合成产物进行了X射线衍射 (XRD)、扫描电镜 (SEM)和力学性能等实验研究。XRD结果表明反应产物中只有TiB2 和 (Cu ,Ni)两相。SEM分析发现增强相TiB2 陶瓷颗粒已经形成骨架状 ,其间为 (Cu ,Ni)基体相 ,TiB2 颗粒形貌为近等轴状 ,尺寸细小且较均匀。合成产物的致密度为 94.2 % ,弯曲强度和断裂韧性分别达到 5 99.4MPa和12 .5 6MPa·m1/ 2 。 相似文献
994.
用量子化学半经验计算方法CNDO/2程序,研究了苯胺类缓蚀剂的电子性质与缓蚀性能的关系。结果表明质子化的胺基是苯胺衍生物与金属作用的活性部位。提出了该类分子作为酸性介质中金属缓蚀剂在铁表面形成吸附膜的作用机理。 相似文献
995.
Sulfidation behavior of Fe-25Cr-20Ni-1.5Al2O3 in simulated coal combustion/gasification environments
The effect of minor addition of -Al2O3 dispersoids on the sulfidation behavior of Fe-25Cr-20Ni was investigated over a range of pO2, 1.13×10–20 to 1.18×10 ****–22 atm. at constant pS2=1.22×10–8 atm. Fe-25Cr-20Ni and Fe-25Cr-20Ni 1.5 Al2O3 with and without preformed oxide scales were exposed to bioxidant gas mixtures H2/H2O/H2S/Ar at 700° C. Both isothermal and cyclic exposures were included. Scales were characterized by a combination of several surface analytical tools. A remarkable improvement in sulfidation resistance is observed in Fe-25Cr-20Ni-1.5Al2O3 under the conditions investigated here. This is attributed to the ability of the alloy to form and maintain a predominantly Cr2O3 scale with reduced Fe-diffusion and content. Possible scientific reasons for such improvement are discussed. The base alloy, Fe-25Cr-20Ni, fails to develop and retain such a Cr2O3 scale and undergoes sulfidation within a few minutes of exposure. The scale breakdown process by sulfidation is explained qualitatively. Experimental evidence suggests that sulfur in the environment enhances Fe-diffusion and content in the scale. 相似文献
996.
本文研究了烧结助剂Ni对C-B_4C-SiC复合材料显微结构与性能的影响.X射线衍射表明Ni在烧结温度下与SiC,B_4C人发生反应在晶界生成Ni_(4.6)Si_2B,并产生液相,有效地促进了C-B_4C-SiC复合材料的烧结,抑制了晶粒的长大,使复合材料密度与强度大幅度地增加,电阻率下降;同时Ni_(4.6)Si_2B在氧化时生成致密的2NiO·B_2O_3,包裹了易氧化的B_4C和C,有效地防止了复合材料的氧化,从而大大提高了制品的抗氧化性能. 相似文献
997.
998.
MODELLINGOFP/MFORMINGPROCESSESBYFEM¥Wei,Yuanping;Ruan,Xueyu(DepartmentofPlasticityTechnology,ShanghaiJiaoTongUniversity,Shang... 相似文献
999.
Effect of growth-interrupted method on quality of AlGaAs/GaAs multiple quantum wells prepared by MBE
AlGaAs/GaAs multi-quantum well (MQW) was prepared by molecular beam epitaxy(MBE) with growth-interrupted heterointerface (GIH) method and continuous growth (CG) method, respectively. The microstructures Of the MQWs were characterized by double-crystal X-ray rocking curve (DCRC) and atomic force microscopy (AFM), and the photoluminescence (PL) properties of the MQWs were also studied. The MQWs grown with GIH method show that higher order satellite peaks of Pendelloesung fiinges are observed in DCRC, the roughness of surface is much reduced in AFM, and the full width at half maximum (FWHM) of exciton line is much narrower in PL. The results indicate that the GIH method reduces the monolayer growth step density at the heterointerface due to the migration of surface atomsfor a few minutes grower interruption, and substantially improves the quality of AlGaAs/GaAs MQWs. 相似文献
1000.
This paper presents an integrated simulation model for full digital controlled PMIG/MAG welding system with Matlab/Simulink, and it consists of power inverter, digital control system and dynamic arc-load model. An integrated simulation study was done for fuU digital PMIG/MAG welding, and a method of connecting dynamic arc-load model to the system with controlled current source was presented, in addition, the simulation results were utilized to study the issues of digital control PMIG/MAG welding in this paper. The experimental results validated the developed simulation model, and this simulation study can be applied in implementation of the full digital PMIG/MAG welding and analysis of system dynamic process. 相似文献