Stellite Superalloy Powder Deposition on 7075 Aluminum Alloy

Abstract

Several types of powders can be deposited on metal alloys for property improvement using thermal spray processes. Aircraft grade 7075 aluminum alloy possesses good mechanical properties but poor wear and corrosion resistance. Thermal spray coatings can improve the poor wear performance of 7075 so that it is suitable for use in severe conditions by depositing a hard, wear-resisting layer over the base material. This can be done by a simple production process while maintaining the base material properties. Among the available coatings, cobalt-base superalloys, such as Stellites, provides excellent protection against corrosion and wear. However, the treatment must not deteriorate the substrate hardness. In the High Velocity Oxygen Fuel (HVOF) thermal spray process, the short resident time of the powder in the flame results in a relatively small temperature increase, which in turn results in a lower substrate temperature during the coating deposition. In the present work, HVOF thermal spray process was used to coat 7075-T3 aluminum alloy samples with Stellite 6 superalloy. This treatment resulted in layers of high hardness and improved wear performance while keeping the base material properties unchanged.