High-Temperature Cyclic Oxidation Behavior of MAX-Phase Coating Partially Pre-Oxidized during the Magnetron Sputtering

We explored the behavior of a layered MAX-phase coating during the high-temperature oxidation. The coating was deposited on a heat-resistant titanium alloy Ti-40%Nb-10%Al-(Zr, Mo, V, Si) (wt. %) using the method of bipolar pulsed magnetron sputtering assisted with gas plasma. The coating’s surface was intentionally oxidized during the synthesis to obtain a dual–layered microstructure: surface layer of 2.0 μm—width contains Ti-based and Al-based oxides additionally to the main MAX-phases Ti3AlC2, Ti2AlC and Ti3AlC (total coating width is 3.8 μm). The MAX-phase coated material was subjected to cyclic oxidation in air at temperature of 700ºС (totally for 98 hours with intermediate cooling in every 7 hours). Pre-oxidized layered coating of MAX-phases shown moderate oxidation behavior. It destructs due to the microblistering of the pre-oxidized surface layer assisting the preservation of the base MAX-phase coating integration with the substrate material. The results of the paper apply the approach for decreasing high-temperature oxidation of MAX-phase coatings by pre-oxidation of the coating during the synthesis.