Effect of Spray Angle and Substrate Material on Coating Formation and Properties of HVAF Sprayed Coatings

Thermal sprayed (TS) coatings can enhance the surface properties of engineering components to extend their performance and service lifetime. The industrial components typically possess complex geometries and are fabricated using different materials, which can influence the deposited coating’s microstructure and performance. High-velocity air fuel (HVAF) spraying is a relatively new TS process that has shown tremendous potential to deposit high performance coatings. However, no detailed studies on HVAF coating formation in relation to the spray angle and substrate properties, and the influence of coating material on the above have been reported so far. The objective of this work was to study the influence of spray angle and substrate material on splat characteristics, coating microstructure evolution, properties and performance for two distinct coating materials.

WC-Co and Inconel 625 coatings were deposited onto three different substrates (aluminium alloy, carbon steel and Hastelloy-X) utilising different spray angles (90º, 60º, and 40º). The coating evolution was analysed utilising SEM. Coatings were subjected to micro-indentation and dry sliding wear test. The results showed that initial splat characteristics were substantially altered on changing the substrate and the spray angle. However, the final coating properties were not affected significantly, suggesting the versatility of the HVAF process.