Amorphous alumina films were deposited by metal-organic chemical vapour deposition (MOCVD) on stainless steel, type AISI 304. The MOCVD experiments were performed in nitrogen at low and atmospheric pressures. The effects of deposition temperature, growth rate and film thickness on the mechanical properties have been studied. The experiments were performed with the dynamic ultra-micro-hardness tester, DUH-200, and the scanning scratch tester, SST-II)]. both developed by Shimadzu. The DUH-200 is associated with crack formation during indentation. This technique involves a qualitative method to study the crack behaviour of the thin alumina films as well as a method to estimate the fracture toughness of the film and the film/substrate interface. The experiments performed with the SST-101 are based on the estimation of the film adhesion to the substrate by determining a critical load; the load where the film starts to spall or to delaminate. The best mechanical properties were obtained using low deposition rates and high deposition temperatures. Therefore, low-pressure MOCVD is recommended in addition to the deposition of alumina films at high temperatures.

Thin amorphous alumina films were prepared on stainless steel, type AISI 304, by low pressure metal-organic chemical vapour deposition. The effect of thermal annealing in nitrogen (for 2, 4 and 17 h at 600, 700 and 800 "C) on the film properties, including the protection of the underlying substrate against high temperature corrosion and the chemical composition of the film, were investigated.Corrosion experiments performed at 450 "C in a hydrogen sulphide-containing gas, showed that the thermal annealing process had a detrimental effect on the protective properties of the alumina films. From FTIR and Auger measurements, it was found that the amorphous alumina, containing boehmite, converted to y-alumina during the annealing process.

Thin alumina films, deposited at 280~ by low-pressure, metal-organic, chemical-vapor