Post-processing of Cold Spray Coatings via Rapid Induction Heating

Cold spray is an additive manufacturing process increasingly used for repair and restoration of damaged components. A common problem with the technology is the high level of porosity in the as-sprayed coatings. Effort has been made in the past to reduce the porosity level by post-processing methods such as heat treatment in vacuum furnace. However, the conventional heat treatment is a slow process which typically takes a few hours. The prolonged heating and cooling cycles reduce productivity and could cause some adverse effects on the components. The current research aimed to develop a rapid technique for post-processing of cold spray coatings. Cold spray was carried out to coat multiple layers of CoNiCrAlY powders onto Inconel 718 substrate. The coatings were then post-processed by induction heating at 800, 900, 1000 and 1100 °C. The experimental results show that induction heating reduced the porosity level significantly in a short period of merely 10 min. The effectiveness of induction heating is attributed to the preferential electrical resistance heating of regions with pores. The study demonstrates the potential application of induction heating for rapid post-processing of cold spray coatings.