Abstract
Chemical vapor infiltration (CVI) is a relatively new fabrication method for forming ceramic composites. The vapor deposition mechanism is determined by the reaction pressure and temperature, as well as the concentration and composition of the reactants. This commentary discusses two mechanisms for the deposition of alumina from AlCl 3 -H 2 -CO 2 gas mixtures, and it explains that the reaction of the gas reactants on the substrate surface is a highly feasible deposition mechanism of the CVI process for forming alumina matrix composites. Comments are also made regarding a recent publication of Middleman in the Journal of Materials Research. © 1990, Materials Research Society. All rights reserved.