HIGH-TEMPERATURE CORROSION-RESISTANT CERAMIC COATINGS OBTAINED BY LASER-CHEMICAL VAPOR-DEPOSITION

An ArF excimer laser-induced CVD method is described in which amorphou s silicon and silica layers were deposited on Incoloy 800H and 2 1/4 C r1Mo steel substrates from a gas mixture of SiH4, (N2O) and Ar for cor rosion protection at high temperatures. A parallel configuration was u sed, which would allow easy scale-up of the method for large area depo sition. All process parameters (SiH4/N2O ratio, total and partial pres sures, substrate temperature, laser repetition rate, energy density an d beam-substrate distance) had been previously optimized for SiO2 depo sition on Si wafers. Based on this experience, SiO2 and a-Si films hav e been deposited on both metallic substrates with and without a sputte r ion-plated TiN interlayer. Samples were characterized by SEM, EDAX a nd AES. Analyses taken before and after corrosion testing in an aggres sive environment at 450 degrees C have demonstrated that these LCVD Si O2 films perform well as diffusion barriers and were resistant to spal ling.