Abstract
Coatings obtained by thermal spray techniques are widely used in many industrial applications where wear and abrasion resistance is required. High Velocity Oxy-Fuel (HVOF) spraying represents the state of the art of such types of coatings. The high velocity of the particles achieved during the spraying process and relatively low temperatures at the point of application enhance bond strength and eliminates substrate deformation by thermal effects. These aspects make the process attractive for high value components. In this work the electrochemical behaviour of both as-sprayed and HIPed Stellite 6 coatings are compared. Hot Isostatic Pressing (HIPing) consists of simultaneous applications of high pressure and high temperature. In this paper HIPing has been used as a post-treatment process for HVOF coating. Electrochemical DC anodic polarisation corrosion experiments were conducted in seawater at 18°C, 30°C, 40°C, 50°C, 70°C and 90°C. To support the electrochemical tests, detailed microscopy was conducted after corrosion tests to determine the attack mechanisms.
