ANALYSIS OF HVOF COATING CHARACTERISTICS FORMED ON THE SURFACE OF SEVERAL CYLINDRICAL COMPONENTS WITH DIFFERENT DIAMETERS

Abstract

Nowaday, the high-velocity oxygen fuel (HVOF) spraying technology is developing and gradually being widely applied in Vietnam. HVOF coating technology is slowly becoming a surface protection solution for components, replacing hard
chrome plating, which has adverse effects on the environment. Essentially, the process of creating internal surface coatings, such as those for molds, valves, and pipes, is extremely complex compared to external surfaces due to the influence of the spraying environment. This paper presents the characteristics of a WC-10Co-4Cr coating sprayed onto the internal surface of CT38 steel for three cylindrical components with diameters of 350mm, 400mm, and 450mm using the HVOF spraying method. The study aims to determine the effect of varying diameters on the microstructure, phase composition, and mechanical properties of the sprayed coatings. The results show that the Ø350 coating has low hardness and high porosity, while the Ø400 coating exhibits the best mechanical properties. The Ø450 coating contains a higher amount of η-carbide phase than the other coatings. Identifying suitable coating characteristics serves as a basis for determining the fixtures and spray gun dimensions for restoration applications, creating internal surface coatings using ID-HVOF.