Improved Corrosion Resistance of HVOF Sprayed Ceramic-Metallic Coatings

Abstract In corrosive media the wear resistance of ceramic-metallic (cermet) coatings depends on the corrosion resistance of the metallic binder. Other factors influencing the coating deterioration are the corrosivity of the media and any galvanic interaction from the surrounding material. The corrosion resistance of the metallic binder should be comparable to the material of the rest of the system. This is especially important when the surrounding materials are corrosion resistant alloys as stainless steels, where the coatings otherwise will act as an anode. This paper summarises results from corrosion tests of different ceramic-metallic coatings sprayed by the high velocity oxygen fuel (HVOF) process. The corrosion properties of the coatings have been compared with results from corresponding tests obtained for stainless steel and some nickel based alloys. The corrosion compatibility and risk of galvanic corrosion is discussed.