Al{sub 2}O{sub 3} coatings as diffusion barriers deposited from particulate-containing sol-gel solutions
- Univ. of Connecticut, Storrs, CT (United States)
- Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering
A procedure for the formation of Al{sub 2}O{sub 3} coatings as diffusion barriers between ductile reinforcements (e.g., Nb and Ta) and intermetallic matrices (e.g., MoSi{sub 2} and NiAl) is described. The coating technique involved sol-gel processing of alumina-forming sols with the addition of submicrometer-sized Al{sub 2}O{sub 3} particles. Cracking in the coatings, a typical shortcoming of alumina sol-gel coating, was overcome by the addition of the fine particles into the sols. The surface charge of the Al{sub 2}O{sub 3} particles was adjusted to be the same as the AlO(OH) colloids in the sols and electrophoresis was used to codeposit Al{sub 2}O{sub 3} and AlO(OH) onto the surfaces of the reinforcements. The alumina gel derived from the sols acted as a binder for the alumina particles, while the particles reduced the shrinkage of the sol-gel coatings and promoted the formation of dense coatings. The thickness of the coatings could be easily controlled without cracking and the effectiveness of the coatings as diffusion barriers was improved substantially.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 177988
- Journal Information:
- Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 12 Vol. 78; ISSN 0002-7820; ISSN JACTAW
- Country of Publication:
- United States
- Language:
- English
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