Virginia Tech Intellectual Properties, Inc.

Center for Innovative Technology

Virginia Polytechnic Institute and State University

Tawei Sun

Jesse J Brown

Nancy R Brown

Min Kang

Mg.sub.x Al.sub.2-2x Ti.sub.1+x O.sub.5 (x.ltoreq.0.2) protective coatings have been developed for both dense and porous substrates, such as SiC and Si.sub.3 N.sub.4, using a chemical solution processing method involving the hydrolysis and condensation of magnesium, aluminum and titanium precursors. The solution viscosities, pH values, H.sub.2 O/alkoxide molar ratios, and dip coating withdrawal rates which are optimum for crack-free Mg.sub.x Al.sub.2-2x Ti.sub.1+x O.sub.5 (x.ltoreq.0.2) are 1.0 to 6.2 cP, pH 1-4.5, molar ratio 1.5-10, and withdrawal rate of 2.2-8.0 cm/min, respectively. Conversion of the amorphous coating to crystalline Mg.sub.x Al.sub.2-2x Ti.sub.1+x O.sub.5 (x.ltoreq.0.2) is achieved by a succession of calcination below 450.degree. C. and a final heat treatment above 1000.degree. C. for ten hours with controlled heating and cooling rates.

Magnesium doped .beta.-aluminum titanate thin film coating

.beta.-Al.sub.2 TiO.sub.5 protective coatings have been developed for both dense and porous ceramics such as SiC and Si.sub.3 N.sub.4 using a chemical solution processing method involving the hydrolysis and condensation of aluminum tri-sec butoxide and titanium butoxide. The solution viscosities, pH values, H.sub.2 O/alkoxide molar ratios, and dip coating withdrawal rates required for crack-free .beta.-Al.sub.2 TiO.sub.5 are 1.0 to 6.2 cP, pH 1-4.5, molar ratio 1.5-10, and withdrawal rate of 2.2-8.0 cm/min, respectively. Conversion of the amorphous coating to crystalline .beta.-Al.sub.2 TiO.sub.5 is achieved by a succession of calcination below 450.degree. C. and a final heat-treatment at 1300.degree. C. for ten hours with controlled heating and cooling rates.

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Blacksburg, VA, United States of America

Tawei Sun