CHEMICAL-VAPOR-DEPOSITION OF SOLID OXIDES IN POROUS-MEDIA FOR CERAMIC MEMBRANE PREPARATION - COMPARISON OF EXPERIMENTAL RESULTS WITH SEMIANALYTICAL SOLUTIONS

Explicit equations correlating chemical vapor deposition (CVD) conditions and substrate parameters to the deposition zone thickness, location of maximum deposition, and pore size evolution of a modified counterdiffusion CVD process (MCVD) are derived from recently developed semianalytical solutions. The permeability reduction ratio and the substrate average pore size as a function of deposition time are calculated using the semianalytical solutions and substrate pore size distribution data. Recently reported experimental data of CVD of ZrO2, TiO2, and Al2O3 in porous substrates are compared with the theoretical results in terms of the location of maximum deposition, deposition zone thickness, permeability reduction ratio, change in average pore size, and pore closure time. The theoretical results agree reasonably well with the experimental findings and provide an improved insight into the MCVD process for ceramic membrane fabrication.