Study on Microstructure and High Temperature Oxidation Resistance of Laser Cladding NiAl-Mo Composite Coating

NiAl-Mo composite coating was prepared on the surface of P92 steel by laser cladding technology. The microstructure and high temperature oxidation resistance of the coating were studied. The results show that a dense and crack-free NiAl-Mo composite coating can be prepared on the surface of P92 steel by laser cladding technology. Ni₃ Al and NiAl are the main phases in the coating. Fe and some Mo elements are dissolved in Ni₃ Al and NiAl to form Ni-based solid solution. The incompletely dissolved Mo exists in the Mo-rich region at the upper part of the coating, and the Mo particles are slightly dissolved at the lower part of the coating. When it is oxidized at 800 ℃ for 162 h, a 600 μm loose oxide film is formed on the uncoated P92 substrate, and a 5 μm dense oxide film is formed on the coating. The coating oxide film is composed of Ni O, Ni Fe₂ O₄ and Al₂O₃. The preparation of NiAl-Mo composite coating on the surface of P92 steel by laser cladding is of great significance to solve the problems of too thick oxide film and easy spalling of P92 steel under high temperature conditions.