High Velocity Oxy-Fuel Spraying and Surface Finish

Abstract

High Velocity Oxy-Fuel (HVOF) spray technique is being adapted by many industries for several diverse applications such as internal combustion engines, fluidized bed combustion, industrial waste incinerators, power generation equipment, gas turbines, and paper and pulp industries. The HVOF-sprayed coatings possess high hardness, low porosity, good adhesion strength, and minimal damage to metallurgical properties of the substrate materials, which make them to provide good corrosion and wear resistance. This chapter describes the HVOF spray technology and its applications in relation to surface finishing. The definitions of the surface roughness parameters as found in ISO 4287 for finished HVOF-coated surfaces are reported. Pre-deposition, as-sprayed deposition and post-deposition surface finish methods and studies are discussed. It is evident from literature studies that with increasing time in service, the HVOF-coated surfaces have been found to retain their surface attributes. The significance of surface finish before the deposition of HVOF spray technique has been discussed with the help of related studies done by various researchers. The advanced techniques used for post-coating surface finish have also been highlighted.