LOW TEMPERATURE CVD ROUTE FOR THE PREPARATION OF ALUMINA COATINGS WITH A HIGH SPECIFIC SURFACE AREA

摘要

We report on low temperature MOCVD of alumina designed for coating sub-millimetric channels of stainless steel substrates and supporting a catalyst at the same time. Coatings were grown from aluminium tri-isopropoxide, at deposition pressurel3.3 kPa and temperature in the range 623K - 973K. They are conformal but present variable thickness on the walls of the channels. Coatings deposited below 753K contain hydroxy-aluminas, with the O/Al atomic ratio decreasing with increasing temperature: it corresponds to boehmite at 623K and to alumina at 753K and above. Most films do not diffract X-rays. Those deposited at 973K or annealed at 1073K consist of crystallized γ-AI_2O_3.