Toward Efficient Cold Spraying of Inconel 718: Understanding the Influence of Coating and Particle Impact Temperatures

The production of Inconel 718 coatings using the cold spray process is often challenging due to the limited plastic deformation of particles upon impact associated with its mechanical properties. This leads to the requirement of high spray parameters to achieve dense coating build-up that may result in high and complex residual stresses that can also affect negatively the substrate and lead to nozzle clogging. In this work, the role of the coating and particle impact temperatures is investigated while ensuring they are decoupled from the particle impact velocity. This allows starting to explore potential ways to produce a sound and quality Inconel 718 coating at reduced spray parameters. To decouple and evaluate the role of the particle impact temperature, powder preheating units with downstream injection are used to decouple the particle impact temperature from the particle impact velocity. Three initial particle temperatures are studied: 25, 400 and 750 °C. The effect of the coating temperature on the deposition process is investigated by controlling this temperature independently of the gas stagnation temperature through the use of induction heating. Deposition efficiency, porosity, and micro-hardness are used to assess the coating quality. The coating time–temperature history is measured to better understand its influence on the deposition of Inconel 718. In this work, an enhanced understanding of the effect of both particle and coating temperatures on the coating process is obtained, and the findings allow the establishment of a potential approach to produce dense coatings using reduced spray parameters.