The Dual Character of MAX Phase Nano-Layered Structure Highlighted by Supersonic Particles Deposition

Abstract

MAX phase compounds offer an attractive mixture of ceramic–metallic properties due to their covalent ionic–metallic nature. Since their discovery, a great interest was attributed to their synthesis and potential applications, but the processing of pure compounds as coatings for industrial large-scale application is still considered a challenge. To date, a limited number of papers have evaluated the build-up of MAX phase coating by cold spray (CS), a novel cost-effective and productive spray technology used in both areas of research and industry. Employing CS, the hot gas-propelled material particles have ballistic impingement on a substrate where they undergo plastic deformation. Because of the brittleness, internal delamination, and limited deformability, the deposition of the pure MAX phase is rather challenging. This paper presents the building-up ability of dense MAX-phase coatings by CS with retained structures and compositions, in close relation with the substrate characteristics and phase composition that influences the dual character ceramic–metallic behaviour. Besides recent literature, the originality of this research consists of pioneering deposition of Ti3AlC2 that emphasizes the ceramic–metallic character influenced by the particle speed and the mechanical properties of both substrate and compound.

Research and Development on Cold-Sprayed MAX Phase Coatings

“…So far, cold-sprayed MAX coatings on metal substrates such as Ti, Cu, Zr, Al, Inconel, and stainless steel have been achieved [10,[20][21][22][37][38][39][40]. Through plastic deformation, metal substrates mechanically interlock with MAX particles, thus resulting in good adhesion between MAX coatings and metal substrates.…”

“…MAX phase coatings prepared via cold spraying have been extensively studied. The successful cold spray deposition of Ti 3 AlC 2 , Ti 3 SiC 2 , Cr 2 AlC, and Ti 2 AlC, as representative MAX coatings, has been reported [20][21][22]. In contrast to thermal spraying, cold spraying offers attractive properties with respect to the preparation of MAX coatings due to the following typical advantages: (1) MAX particles experience little oxidation and no decomposition upon low-temperature cold spraying, and the resulting coatings retain the original composition and properties of the employed powders; (2) MAX coatings are dense and their bonding strength is high under high-energy impacts; (3) compressive residual stresses rather than tensile stresses are generated in MAX coatings, which is beneficial to a coating's integrity.…”