Strengthening of alumina by formation of a mullite/glass layer on the surface

Journal Article · Tue Jul 01 04:00:00 EDT 1997 · Journal of the American Ceramic Society

DOI:https://doi.org/10.1111/j.1151-2916.1997.tb03064.x· OSTI ID:529546

Kim, H E; Kim, S H ^[1]; Moorhead, A J ^[2]

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1. Seoul National Univ. (Korea, Republic of). Dept. of Inorganic Materials Engineering
2. Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

A layer composed of mullite and silicate glass was caused to form on the surface of a high-purity alumina ceramic in order to enhance the strength of the material. The layer was formed by exposing the specimens above a bed of SiC platelets at 1,400 C to a flowing H{sub 2} atmosphere containing {approximately}0.1% H{sub 2}O. A reaction between the SiC platelets and the H{sub 2}O in the atmosphere, forming SiO{sub 2} smoke which was deposited on, and reacted with, the alumina substrate. The strength of the ceramic was significantly improved by the reaction layer, which was found to be comprised of mullite and silicate glass. The increases in strength (about 60% above that of the material in the as-polished condition) was attributed to the blunting of surface cracks. A similar strengthening effect was observed in samples of the material which had been ground with a 220-grit diamond abrasive wheel (as had all of the samples) but not polished.

• Sponsoring Organization: Korea Science and Engineering Foundation (Korea, Republic of)
• OSTI ID: 529546
• Journal Information: Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 7 Vol. 80; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
FLEXURAL STRENGTH
GLASS
LAYERS
MECHANICAL PROPERTIES
MORPHOLOGY
MULLITE
SILICATES
SURFACES
X-RAY DIFFRACTION