Vapor Deposition of Ceramic Oxides.
Abstract
Thin coatings of dense chemically vapor deposited Al2O3 were prepared in Al2O3 substrates and strength measurements made to determine if the mechanical properties of conventionally formed materials could be enhanced. Results showed that even with thin coatings (1-10 mils), fissures develop between the mis-oriented anisotropic grains of the Al2O3 coating. These cracks then propogate through the coating into the substrate giving lower strengths then the original substrate. Several methods were investigated to chemically vapor deposit MgO under controlled conditions which were compatible with the conditions for simultaneously depositing Al2O3. The method which appears most favorable is that which utilizes the flow of H2 and Cl2 over MgO granules at elevated temperatures resulting in the generation of MgCl2 and then the hydrolysis of the chloride. Alloys based on an isotropic cubic structure such as MgO or MgAl2O4 or two-phase mixtures will be required for high mechanical strength free standing vapor deposited oxides. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1969
- Accession Number
- AD0864944
Entities
People
- B. Albanese
- W. A. Waugh
- W. D. Kingery