Deposition of α-alumina via combustion chemical vapor deposition

Combustion chemical vapor deposition was used to synthesize alpha-alumina thin films. The deposition solutions were 0.0015 M aluminum acetylacetonate dissolved in isopropanol. Fused silica and nichrome (Ni-20Cr) served as substrates. Deposition temperatures were in the range of 1050 degrees C to 1125 degrees C. Crystalline films consisting of hexagonal alpha-grains were produced on both substrates. Some films on nichrome displayed preferred orientations of (113) and (116) normal to substrate surfaces, while films deposited on silica showed no preferred orientation. Films deposited on nichrome seemed denser than those on silica as the grains clustered together to provide a 'cauliflower' appearance. The oxidation response of uncoated and alumina-coated nichrome specimens was measured by isothermal thermogravimetric analysis in pure flowing air at 900 degrees C, 1000 degrees C and 1100 degrees C. The coated specimens had significantly lower mass gain values and parabolic rate constants than their uncoated counter parts. (c) 2006 Elsevier B.V. All rights reserved.