MODELING AND ANALYSIS OF CVD PROCESSES FOR CERAMIC MEMBRANE PREPARATION

A mathematical model is presented that describes the modified chemical vapour deposition (CVD) process (which takes place in advance of the electrochemical vapour deposition (EVD) process) to deposit ZrO2 insid e porous media for the preparation and modification of ceramic membran es. The isobaric model takes into account intrapore Knudsen diffusion of ZrCl4 and H2O, which enter the membrane from opposite sides, and La ngmuir-Hinshelwood reaction of the solid product ZrO2 on the internal pore wall. The processes occurring in one single pore are investigated , and the change in pore geometry during deposition is taken into acco unt. Based upon this model, the deposition profile is studied. The mod el fits reasonably well with experimental results.