To solve the problem of macro-crack and residual silicon content of SiC ceramic parts caused by the carbon black agglomeration and insufficient content

an effective method to control the micro-structure defect and residual silicon content and to improve the mechanical properties of SiC ceramic parts at high temperature was proposed. Short carbon fibers(CF)serve as the carbon source

the dispersibilities of carbon black and short carbon fiber in ceramic slurry were comparatively investigated and the influences of the two carbon sources on the quality of the green body were analyzed. The mic

ro-structure and phase composition of the reaction infiltrated Cf/SiC ceramic were observed by SEM and XRD. The effects of carbon fiber content on high temperature bending strength and fracture toughness of the SiC ceramic were discussed. The results show that short carbon fibers better disperse in ceramic slurry

and large-size pores and cracks in the ceramic green body can be well controlled. When in the reactive melt infiltration process

the porous structure formed by carbon fiber and ceramic particles facilitate the infiltration of liquid silicon

and the carbon fiber dissolves in the silicon liquid and reacted form β-SiC surrounding the carbon fiber surface. As the volume fraction of short carbon fiber increases(0 to 40%)

the residual silicon content in the ceramic matrix decreases

and the high temperature(1 350 ℃)performance of the ceramic part increases firstly then decreases. When the short carbon fiber volume fraction gets 20%

the high-temperature flexural strength and fracture toughness reach the highest

343±19 MPa and 5.04±0.27 MPa·m

1/2

respectively.