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大尺寸轻型碳化硅质镜体的制造与材料性能测试 被引量:24
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作者 张舸 赵汝成 赵文兴 《光学精密工程》 EI CAS CSCD 北大核心 2006年第5期759-763,共5页
利用凝胶注模(gel-casting)成型工艺制备了620 mm和700 mm×300 mm的碳化硅(SiC)轻型反射镜素坯,经过脱模、干燥、脱脂和反应烧结等工艺,制备了反应烧结SiC(RB-SiC)镜体。镜体经过加工和测试,结果表明:制备的RB-SiC内部结构均匀致... 利用凝胶注模(gel-casting)成型工艺制备了620 mm和700 mm×300 mm的碳化硅(SiC)轻型反射镜素坯,经过脱模、干燥、脱脂和反应烧结等工艺,制备了反应烧结SiC(RB-SiC)镜体。镜体经过加工和测试,结果表明:制备的RB-SiC内部结构均匀致密;力学性能和热学性能优异,抗弯强度、断裂韧性和热膨胀系数分别达到了350 MPa、4.1 MPa.m1/2和2.67×10-6/K;镜体经抛光后的表面粗糙度RMS值可优于3 nm,适合用于制备空间用大尺寸轻型反射镜。 展开更多
关键词 凝浇注模 轻型反射镜 反应烧结碳化硅
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Simulation of stray grain formation during unidirectional solidification of IN738LC superalloy 被引量:1
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作者 李响妹 张捷宇 +2 位作者 王波 任忠鸣 周国治 《Journal of Central South University》 SCIE EI CAS 2011年第1期23-28,共6页
The influence of casting parameters on stray grain formation of a unidirectionally solidified superalloy IN738LC casting with three platforms was investigated by using a 3D cellular automaton-finite element (CAFE) m... The influence of casting parameters on stray grain formation of a unidirectionally solidified superalloy IN738LC casting with three platforms was investigated by using a 3D cellular automaton-finite element (CAFE) model in CALCOSOFT package. The model was first validated by comparison of the reported grain structure of AI-7%Si (mass fraction) alloy. Then, the influence of pouring temperature, heat flux of the lateral surface, convection heat coefficient of the cooled chill and mean undercooling of the bulk nucleation on the stray grain formation was studied during the unidirectional solidification. The predictions show that the stray grain formation is obviously sensitive to the pouring temperature, heat flux and mean undercooling of the bulk nucleation. However, increasing the heat convection coefficient has little influence on the stray grain formation. 展开更多
关键词 computer simulation unidirectional solidification stray grain grain structure
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