ON THE KINETICS OF MODIFIED CVD IN POROUS CERAMICS

This paper reports a kinetic study on modified CVD process in porous c eramic substrates by both theoretical analysis and experimental approa ch. The theoretical analysis indicates that with a heterogeneous chemi cal reaction the decrease of the pore size is proportional to the depo sition time and the pore closure time is proportional to the original pore size. While for a homogeneous reaction the pore size decreases ex ponentially with the deposition time and it is very difficult to achie ve pore closure. The experimental results indicate that the deposition of YSZ in porous ceramics is a heterogeneous reaction.