The Characters of Mo-MoSi_2 Functionally Graded Coating

摘要

Mo-MoSi_2 functionally graded coating on Mo substrate is prepared by siliconizing technology. The characters of Mo-MoSi_2 functionally graded coating are analyzed by SEM, EDS, GDS and XRD. The result shows that Mo-MoSi_2 functionally graded coating is dense and smooth, without pore and crack defects, gradient coating and Mo matrix achieve good metallurgy bond. The silicon molybdenum atom ratios (Si/Mo) in functionally graded coating appear three changing regularities. When the Si/ Mo of outer layer are from 6:1 to 2:1, the surface phase is constituted by MoSi_2 and Si; when the Si/Mo of interlayer is about 2:1, the interlayer phase is constituted by MoSi_2; when the Si/Mo of transitional layer are from 2:1 to 0:1, the transitional layer phase is constituted by Mo_5Si_3 and Mo. The phase structure of Mo-MoSi_2 functionally graded coating from outside to inside is outer layer MoSi_2+Si, interlayer MoSi_2 and transitional layer Mo_5Si_3+Mo_3Si three-layer structure. The thermodynamic calculation results are consistent with the experimental results substantially.