Development of Mo(Si,Al)2-MoB composite coatings to protect TZM alloy against oxidation at 1400 °C

Mo(Si,Al)2-MoB composite coatings were deposited on TZM alloy by a single-step pack cementation process. The microstructure development of the coatings and the influence of deposition temperature on the coating structure are investigated. The coatings form via a sequence manner of first Al depositing and then Al-Si-B or Si-B co-depositing, while increasing the deposition temperature will move Al-Si-B or Si-B co-depositing ahead during the process. The coatings prepared at 1250 °C for more than 4 h consist of thick Mo(Si,Al)2 outer layer with dispersed MoB particles and thin MoB inner layer. The oxidation-resistant performance and degradation mechanism for the coatings during oxidation at 1400 °C are discussed.