SILICON-CARBIDE MEMBRANES MODIFIED BY CHEMICAL-VAPOR-DEPOSITION USINGSPECIES OF LOW STICKING COEFFICIENTS IN A SILANE ACETYLENE REACTION SYSTEM/

Asymmetric SiC membranes are modified by a SiH4/C2H2/Ar low-pressure c hemical vapor deposition (LPCVD) system at a temperature of 800 degree s C. The pore size of the membrane is reduced to increase its selectiv ity at the expense of its permeance. The chemical vapor deposition (CV D) modification, using a chamber to minimize the gas-phase reaction, i s superior to that without a chamber, because the film-forming species of low sticking coefficients can improve the pore size at a lower cos t of permeance reduction. With the knowledge of pore structure and CVD kinetics, the alteration of membrane properties can be properly predi cted.