Corrosion behavior of protective CVD coatings based on metastable phases of tungsten in a solution of hydrochloric acid and hydrogen sulfide

The paper presents data on the corrosion resistance of coatings based on metastable phases of tungsten in the W–C system, obtained by chemical deposition from the gas phase (CVD – chemical vapor deposition) in hot concentrated solutions of hydrochloric acid and hydrogen sulfide, simulating media that can be in contact with metal surfaces of oil and gas equipment during hydrochloric acid treatment of the bottomhole zone wells. It is shown that the corrosion rate of coatings in all media does not exceed 20 microns/year, while their anticorrosive ability practically does not depend on their mechanical characteristics. Also, the extended exposure in hydrochloric acid solution showed that the penetrability of the coatings does not exceed 0.02%.