Preparation and high‐temperature oxidation resistance of multilayer MoSi2/MoB coating by spent MoSi2‐based materials

Spent MoSi2 and MoB were used as raw materials to prepare multilayer MoSi2/MoB coating on molybdenum by the two‐step method of slurry deposition and spark plasma sintering. The results showed dense MoSi2/MoB coating after sintering while penetrated cracks appeared in MoSi2 coating due to coefficient of thermal expansion mismatch between the Mo substrate and coating. After the sintering of MoSi2/MoB coatings, MoB and Mo2B diffusion layers were formed between MoB transition layer and Mo substrate without defects, exhibiting good metallurgical bonding. The high‐temperature oxidation behavior of coatings (1500°C) was also explored. After oxidation of 50 h at 1500°C, lowest mass gain (0.035 mg/cm2) was obtained for MoSi2/MoB coating, and the oxide scale was dense and complete without voids, making the oxygen diffusion at elevated temperature inhibited. Compared with MoSi2 coating under the same oxidation conditions, relatively thinner silica oxide scale was acquired by MoSi2/MoB coating because of the reduction of cracks, and the multilayer coating exhibits better anti‐oxidation properties at high temperature. Two‐step method of slurry deposition and spark plasma sintering was applied to prepare MoSi2/MoB multilayer coating on Mo. The multilayer coating possessed improved anti‐oxidation properties with dense and complete oxide scale after 1500°C oxidation.