High-temperature corrosion-resistant ceramic coatings obtained by laser chemical vapour deposition

Abstract

An ArF excimer laser-induced CVD method is described in which amorphous silicon and silica layers were deposited on Incoloy 800H and 2 1 4 Cr1Mo steel substrates from a gas mixture of SiH 4, (N 2O) and Ar for corrosion protection at high temperatures. A parallel configuration was used, which would allow easy scale-up of the method for large area deposition. All process parameters (SiH 4/N 2O ratio, total and partial pressures, substrate temperature, laser repetition rate, energy density and beam-substrate distance) had been previously optimized for SiO 2 deposition on Si wafers. Based on this experience, SiO 2 and a-Si films have been deposited on both metallic substrates with and without a sputter ion-plated TiN interlayer. Samples were characterized by SEM, EDAX and AES. Analyses taken before and after corrosion testing in an aggressive environment at 450°C have demonstrated that these LCVD SiO 2 films perform well as diffusion barriers and were resistant to spalling.