Silicon Nitride Coatings on Molybdenum by RF Reactive Ion Plating

Rf reactive ion plating technique has been applied to the preparation of protective silicon nitride coating on molybdenum. All the deposits prepared at deposition temperature of less than 1000°C were amorphous. Silicon in deposits was found to be present as nitride by Auger electron spectroscopic, infrared absorption spectroscopic, and x‐ray diffraction analyses. Nearly stoichiometric silicon nitride deposits were obtained at a deposition rate of as high as 1 μm/min. Several factors affecting the stoichiometry of the silicon nitride were discussed. Oxidation test of the coated specimens showed that the silicon nitride layer obtained under optimum conditions protected the molybdenum substrate from oxidation in Ar‐1% gas mixtures up to approximately 1200°C. Typical pitting corrosion was observed in the coating film at the higher temperatures.