Elements Diffusion of Al-Si Coating on Nickel-Base Superalloy K4104 in High Temperature Oxidation Process

Al-Si binary diffused coatings were prepared on nickel-base superalloy K4104 by the slurry process.According to GB/T13303-91,the high temperature oxidation experiment at 1000℃ of specimens with coating and without coating was carried out with static mass gain method.Surface and section morphology and content of the oxide layer were studied by means of SEM/EDX,and the elements diffusion for the samples in the high temperature oxidation was analyzed.The results indicated that diffusion between Al-Si coatings and the superalloy substrate caused a 120~140μm thick coating structure.In the processing of oxidation,the content of Al in the surface layer decreased,but steady β-NiAl phase in this layer could be kept.As the diffusion continued,there was more Si in the outer and inner layer,the Cr₃Si and M₆C which contain rich Si were helpful for preventing the diffusion between the coating and the substrate,and reducing the rate of compound formation.It indicates that Al-Si coating had active effect on high temperature oxidation resistance.