Influence of MAX-Phase Deformability on Coating Formation by Cold Spraying
Andreas Elsenberg, Marco Busato, F. Gärtner, Alexander List, Alessia Bruera, Giovanni Bolelli, Luca Lusvarghi, Thomas Klassen
Abstract
Abstract As solid-state deposition technique avoiding oxidation, cold gas spraying is capable of retaining feedstock material properties in the coatings, but typically fails to build up coatings of brittle materials. Ceramic MAX phases show partial deformability in particular lattice directions and may thus successfully deposit in cold spraying. However, deformation mechanisms under high strain rate, as necessary for cohesion and adhesion, are not fully clear yet. A MAX-phase deposit only builds up, if the specific mechanical properties of the MAX phase allow for, and if suitable spray parameter sets get realized. To investigate the influence of material properties and deposition conditions on coating microstructure and quality, three MAX phases, Ti 3 SiC 2 , Ti 2 AlC and Cr 2 AlC, were selected. Up to ten passes under different spray parameters yielded Ti 2 AlC and Cr 2 AlC coatings with thicknesses of about 200-500 µm. In contrast, Ti 3 SiC 2 only forms a monolayer, exhibiting brittle laminar failure of the impacting particles. In all cases, the crystallographic structure of the MAX-phase powders was retained in the coatings. Thicker coatings show rather low porosities (< 2%), but some laminar cracks. The deposition behavior is correlated with individual mechanical properties of the different MAX-phase compositions and is discussed regarding the particular, highly anisotropic deformation mechanisms.