Si/ SiC coatings on C/ SiC composites and their effects on the structure of the substrate

Si/ SiC coatings were prepared on C/ SiC composites by a slurry-precoating reaction process. The slurrycomponent s with which non-cracked coatings were prepared were concluded through theoretical calculation and experiment s. The effects of powder embedded sintering and vapor silicon vacuum-reaction-sintering atmosphere on themorphology and components of the Si/ SiC coatings were studied. The effect s of single-coating-process (SCP) anddouble-coating-process (DCP) on the st ructure of the subst rate were compared. The micrographs of the coatingswere observed by SEM. The component s and crystal st ructure of the coatings were analyzed by XRD. The result sshow that the non-cracked coatings prepared with slurry in which the mass ratio of C∶Si is 1∶1. 25 and the coatingsprepared by vapor silicon vacuum- reaction- sintering are dense and st rongly bonded with the subst rate , while thecoatings prepared by powder embedded sintering become powder. The st ructure of the subst rate becomes denserthan the coatings prepared by SCP , while the subst rate remaines porous af ter being coated by DCP.