MAX phase ceramic coatings fabricated by aerosol cold spray

MAX phases are a promising material group for high-temperature coating applications. Currently, the search for sustainable MAX phase synthesis and coating techniques suitable for this particular material group is still ongoing. One of the most promising method is cold spray, which prevents the thermally-induced phase changes of the coating material during deposition, while drastically reducing the energy and gas required for the process in comparison to other thermal spraying techniques. In this work, a modified low pressure cold spray (LPCS) system – aerosol cold spray (ACS) has been successfully used to fabricate Ti₂AlC, Cr₂AlC and Ti₃AlC₂ coatings on carbon steel substrate. Structural and microstructural analysis indicated successful deposition of dense and crack-free coating without inducing phase changes during the spraying process using compressed air as process gas. Additionally, post-processing of the coatings by free- and spark plasma sintering methods were tested. The analysis of post-processed coating’s microstructure indicated the increase of interparticle bonding within the coating, however free sintering method resulted in cracking within Ti₃AlC₂ coating, and formation of porosity in Cr₂AlC coating, due to intense diffusion of aluminum towards the carbon steel substrate. This work presents the first successful deposition of MAX phase coatings using a LPCS-based technique, as well as post-processing and characterization of their structural and mechanical properties.