Improvement of high-temperature oxidation resistance to water vapor by alumina coating on beta-sialon ceramic

Abstract

To improve oxidation resistance to water vapor in high-temperature environment, alumina (Al 2 O 3 ) film is coated on β-sialon (z=3) ceramic. Aluminum alkoxide (Al(OBt) 3 ) with diethanolamine and ethanol and Al 2 O 3 sol with ethanol were used as precursor solutions. These precursors were coated on β-sialon substrate by dip coating method and the coated sample was heated at 600°C for 1 h (as-coated sample). The as-coated sample was heat-treated at 1300°C in Ar/O 2 (95/5 vol%) for 2 h and subsequently treated in Ar for 10 h (heat-treated sample). The samples were oxidized in Ar/O 2 /H 2 O (8/2/90 vol%) at 1200°C for ~100 h. The heat-treated samples showed high oxidation resistance to water vapor comparing with as-coated sample.