Remote microwave plasma enhanced chemical vapour deposition of alumina on metallic substrates

摘要

This paper is devoted to the discussion of insulating aluminium oxide layers deposited on metallic substrates in the afterglow region of a microwave oxygen plasma. The chosen organometallic precursor, trimethylaluminium (TMA), has high vapour pressure and reactivity. The experimental set-up is described and the influence of the deposition parameters on deposition rate, physical and chemical properties of the coatings is presented. Deposition rates range from 0.05 to 0.2μm min{sup}(-1). Microwave power and pressure ranges are limited by the formation of particles produced by homogeneous nucleation in the gas phase for high values. Weight gain, which illustrates the deposition rate, is strongly dependent on the precursor flow rate. Density and chemical composition are improved by deposition temperature. The main impurities are CH{sub}x groups. High compressive stresses and electrical resistivity are well suited for the planned uses of these coatings at high temperature on turbine blades.