Study of the Behavior of Mo 40 Si 40 B 20 Coatings in the Temperature Range of 1000–1200°С

The resistance of Mo40Si40B20 magnetron coatings to high-temperature oxidation in the 1000–1200°С temperature range is investigated. The main phases of the initial coating are high-temperature β‑MoSi2 with a hexagonal lattice and t-MoB. The phase transition of β-MoSi2 phase into the low-temperature tetragonal α-MoSi2 one proceeds at 1000°С. After annealing, the main structural components of the coating are the t-MoSi2, t-Mo5Si3, and t-MoB phases. The size of the formed crystallites’ of the t-MoSi2, t‑Mo5Si3, and t-MoB phases increases 1.5-fold at 1000–1200°С. The coatings oxidation is studied at 1200°С in the isothermal and non-isothermal modes. After annealing on the surface, a dense oxide SiO2 layer formed and prevented the diffusion of oxygen to the substrate and its subsequent oxidation. In the case of non-isothermal annealing, the protective oxide layer’s thickness increases 2.6–3.6-fold compared to that during isothermal holding for the same holding time.