热处理温度对制备β-SiC结合SiC材料的影响

Effects of hot treat temperatures on preparation of β-SiC bonded SiC materials

以绿碳化硅、单质硅和炭黑微粉为原料,以聚乙烯基吡咯烷酮(K90)为结合剂,采用注浆工艺制备碳化硅坯体,然后在埋炭(焦炭)保护气氛中分别于1 000、1 200、1 420和1 510℃保温3 h热处理,主要研究了热处理温度对β-SiC结合SiC材料的致密度、强度、物相组成、显微结构等的影响,并探讨了β-SiC的生成生长机制。结果表明:1 000℃热处理后试样的致密度和强度较低,没有生成β-SiC;1 200和1 420℃热处理后试样的致密度和强度均比1 000℃热处理后试样的大,并且生成了较多β-SiC晶须;1 510℃热处理后试样的致密度和强度均比1 200和1 420℃热处理后试样的小,并且生成的β-SiC晶须的长径比也比1 200和1 420℃热处理后试样的小。

The SiC green bodies were prepared by grouting technology using green SiC,Si and carbon black micropowder as starting materials,polyvinyl pyrrolidone (K90)as a binder.Then the green bodies were hot treated in carbon (coke)embedded atmosphere at 1 000,1 200,1 420,and 1 510 ℃ for 3 h,re-spectively.Effects of the hot treat temperatures on the density,strength,phases composition and micro-structure of specimens were investigated,and the growth mechanism of β-SiC was also discussed.The re-sults show that,for the specimens hot treated at 1 000 ℃,the density and strength are low,there is noβ-SiC;for the specimens hot treated at 1 200 and 1 420 ℃,the density and strength are both higher than those of the specimens at 1 000 ℃,and there are a lot of β-SiC whiskers;for the specimens hot treated at 1 510 ℃,the density and strength are low,and the formed β-SiC whiskers have smaller length-diameter ratio than the specimens hot treated at 1 200 and 1 420 ℃.