Preparation of SiC Ceramic by Liquid Silicon Infiltration of Carbonaceous Preform Incorporated with Starch

The purpose of this study is to explore new methods to prepare reaction bonded silicon carbide(RBSC) materials with high performance in a lower cost. Unlike the traditional RBSC process, a pure carbonaceous preform was made of petroleum coke in which cornstarch was incorporated to adjust the preform carbon density and micropore structure as well. The pure carbonaceous preform was then infiltrated with liquid silicon and the sintered materials has a density of 3.12g/cm3 and bending strength of 580MPa. The results of observation on the preform microstructure show that the preform with starch contains more fine pore, which is believe to be vital for complete infiltration. XRD analysis shows that the sintered materials contain β-SiC and free Si and a little free carbon. SEM shows the average granule size in the sintered materials is about 2-4μm and is less than that of the traditional RBSC. We conclude that finer grain is the main cause to the higher strength of the material in comparison with the traditional RBSC.