Cold Spray Forming Inconel 718

Cold spray technology has tremendous potential for producing thick coatings with soft metals such as aluminum and copper. However, high critical velocity, residual stresses and technical issues such as nozzle clogging have limited the number of materials that could have been cold spray formed. For example, although the aerospace industry would consider cold spray forming Inconel for many potential applications, this material has been challenging to spray mainly due to nozzle clogging. This problem has been recently solved in commercial cold spray equipment by using non clogging nozzle material combined with a nozzle water cooling system.

In this work, Inconel 718 powder was cold sprayed using a Plasma Giken PCS-305 equipment to produce thick coatings on aluminum tubes using both helium and nitrogen as the propellant gases. The spray conditions were optimized based on in-flight particle velocity measurements. The spray formed parts were sectioned to produce several samples for material characterisation through SEM, EDS and XRD and for mechanical tensile and compressive testing. The effect of post sprayed heat treatment was also investigated.