High performance thermal-sprayed WC-10Co-4Cr coatings in narrow and complex areas

Abstract

A complex geometry is always a challenge for the thermal spray community, because the spray angle affects the droplet’s impact on the substrate resulting in changes in coating properties. In this work, an attempt has been made to overcome this limitation. WC-Co-Cr coating was deposited on the CA6NM steel using newly developed high-velocity oxy liquid fuel (HVOLF) thermal spraying gun. As-sprayed coatings were analysed using x-ray diffraction, scanning electron microscopy for phase and microstructural analysis, respectively. Coating microhardness and porosity were also measured. Adhesion strength tests were conducted to determine the mechanical properties of the as-sprayed coatings. Results show that the coating produced by the HVOLF thermal spray system is excellent in terms of mechanical properties achieved. The angular design of this gun allows spraying in narrow areas, complex parts and inside internal diameter minimum as 140 mm having almost uniform coating properties at both spray angles (45° and 70°); this makes it a promising solution for coating deposition on complex geometries.