A silica (SiO2) layer was deposited on the surface of an AlN ceramic in order to increase the strength and to prevent the high-temperature oxidation of the material. The layer was formed on the surface by exposing coupons to the atmosphere downstream of a bed of SiC powder in a flowing H2-0.1% H2O atmosphere at 1450°C. A reaction between the SiC powder and H2O in the H2 gas resulted in the generation of SiO2 'smoke' in the product gas stream. Part of the SiO2 smoke was subsequently deposited on the surface of the AlN specimen to form a dense and uniform SiO2 layer. The strength of AlN was improved by about 20% apparently because of blunting of surface defects by SiO2. More importantly, the layer was very effective in protecting the AlN from the oxidation at elevated temperatures, through the inhibition of transport of oxidants to the sample surface.
|Number of pages||5|
|Journal||Journal of the American Ceramic Society|
|Publication status||Published - 2000 Jan 1|
ASJC Scopus subject areas
- Ceramics and Composites
- Materials Chemistry