GASEOUS CORROSION MECHANISMS OF SILICON CARBIDES IN NA2SO4 AND V2O5 ENVIRONMENTS

Hot-pressed polycrystalline SiC (HPSiC) and single crystal SiC (SCSiC) were exposed to Na2SO4 and V2O5 vapours at 1000 degrees C. Vapours we re carried by the argon gas over the specimens where corrosion studies were conducted. Mixed-kinetics mechanisms for HPSiC under gaseous env ironments have been developed in the form of corrosion weight loss per unit a rea with time. The decomposed gases diffusing through the SiO2 film and. the reaction products at the substrate surfaces are the two major steps that contribute to the overall reaction for this material . SCSiC was observed to have severe corrosion attacks on its surfaces and corrosion pits with honeycomb shapes were left.