Making graphite,SiC,clay,silicon powder etc.as the raw material to process the graphite SiC crucible,the below are some results about the oxidation resistance from different factors such as:the raw material constitution,firing temperature,the method of forming and the different coating on the surface.
1) The firing temperature has a big influence on the density,and the density will lead to the service life of the crucible. When the temperature reach 1150 centigrade,the porosity of the graphite-SiC crucible is the lowest,and the density is the best.
2) The content of the SiC is also very important to the oxidation resistance of the graphite crucible,with the content of the SiC increasing,the porosity of the crucible is reducing,and the performance of the oxidation resistance will be better. The content between 35~50%,the porosity and weight loss rate are the best,when the content of SiC reach 50%,the density will be the highest,and the oxidation resistance is the best.
3) The silicon powder also has influence on the graphite-SiC crucible oxidation resistance,and with the different contents of the silicon powder changing,it can improve the the porosity,density and the oxidation resistance performance. When the silicon powder reach 15% content,the oxidation resistance performance is the best.
4) Different methods of forming also have different influence on the performance of the graphite-SiC crucibles. After the comparison between machine molding and isostatic molding,we could found that the way by isostatic molding is better than the machine molding ,because of the better density,lower weight loss rate,so it can tell that the oxidation resistance performance is better than the isostatic molding.
5) The coating on the surface of the crucible and the wall thickness also have influence on the oxidation resistance performance. When the thickness of the coating is the same,the crucible with B2O3 can reduce the weight loss rate of the crucible,and at the same time it can improve the oxidation resistance performance,and when the content of the coating is the same,the multi-storey coating is better than the single-storey on the density and the weight loss rate,and increase the oxidation resistance performance.
