The forming process of silicide coatings on pure Mo and Mo-base alloys, obtained by the gas- phase deposition method. has been studied by examining the microstructure of coatings and the relationship between coating t...The forming process of silicide coatings on pure Mo and Mo-base alloys, obtained by the gas- phase deposition method. has been studied by examining the microstructure of coatings and the relationship between coating thickness and process parameters. It was shown that the growth of coatings was diffusion-controlled, the diffusion of silicon to be coated into Mo or Mo-base alloys was mainly responsible for the formation of silicide. The relationship between initial silicide thickness and oxidation resistance was also investigated, and the equation of service life of the coatings at high temperature in air is presented.展开更多
Pure silicide coating and Y-Ce modified silicide coating were prepared on Ti-6Al-4V alloy by pack-cementation process. The structures as well as the isothermal oxidation behaviors of the coatings were comparatively st...Pure silicide coating and Y-Ce modified silicide coating were prepared on Ti-6Al-4V alloy by pack-cementation process. The structures as well as the isothermal oxidation behaviors of the coatings were comparatively studied. The results showed that both pure silicide coating and Y-Ce modified silicide coating prepared at 1080℃ for 4 h were composed of a TiSi2 outer layer, a TiSi middle layer and a Ti5Si4 inner layer. The oxidation tests showed that the Y-Ce modified silicide coating possessed much better oxidation resistance than the pure silicide coating at 1000℃, implying the beneficial effects of Y and Ce on the oxidation resistance of the coating.展开更多
Silicide coating was prepared on electro-deposited nickel layer by the slurry pack cementation process on copper matrix at 1173 K for 12 h using SiO2 as Si source, pure Al powder as reducer, a dual activator of NaF＋N...Silicide coating was prepared on electro-deposited nickel layer by the slurry pack cementation process on copper matrix at 1173 K for 12 h using SiO2 as Si source, pure Al powder as reducer, a dual activator of NaF＋NH4Cl and albumen （egg white） as cohesive agent. Microstructure, properties and siliconizing mechanism of silicide coating were discussed. The experimental results show that the silicide coating with 220 μm thickness is mainly composed of a Ni2Si phase and a small amount of Ni31Si12 phase. Its mean microhardness （HV 790） is ten times than that of copper substrate （HV 70）. The coefficient of friction decreases from 0.8 of pure copper to about 0.3 of the siliconzed sample. SiF2, SiCl2 and SiCl3 are responsible for the transportation and deposition of Si during the slurry pack cementation process.展开更多
文摘The forming process of silicide coatings on pure Mo and Mo-base alloys, obtained by the gas- phase deposition method. has been studied by examining the microstructure of coatings and the relationship between coating thickness and process parameters. It was shown that the growth of coatings was diffusion-controlled, the diffusion of silicon to be coated into Mo or Mo-base alloys was mainly responsible for the formation of silicide. The relationship between initial silicide thickness and oxidation resistance was also investigated, and the equation of service life of the coatings at high temperature in air is presented.
基金Project supported by the Shanxi Science and Technology Research and Development Program(2013KJXX-08)
文摘Pure silicide coating and Y-Ce modified silicide coating were prepared on Ti-6Al-4V alloy by pack-cementation process. The structures as well as the isothermal oxidation behaviors of the coatings were comparatively studied. The results showed that both pure silicide coating and Y-Ce modified silicide coating prepared at 1080℃ for 4 h were composed of a TiSi2 outer layer, a TiSi middle layer and a Ti5Si4 inner layer. The oxidation tests showed that the Y-Ce modified silicide coating possessed much better oxidation resistance than the pure silicide coating at 1000℃, implying the beneficial effects of Y and Ce on the oxidation resistance of the coating.
基金Funded by the Natural Science Fundation of Southeast University(9212002232)
文摘Silicide coating was prepared on electro-deposited nickel layer by the slurry pack cementation process on copper matrix at 1173 K for 12 h using SiO2 as Si source, pure Al powder as reducer, a dual activator of NaF＋NH4Cl and albumen （egg white） as cohesive agent. Microstructure, properties and siliconizing mechanism of silicide coating were discussed. The experimental results show that the silicide coating with 220 μm thickness is mainly composed of a Ni2Si phase and a small amount of Ni31Si12 phase. Its mean microhardness （HV 790） is ten times than that of copper substrate （HV 70）. The coefficient of friction decreases from 0.8 of pure copper to about 0.3 of the siliconzed sample. SiF2, SiCl2 and SiCl3 are responsible for the transportation and deposition of Si during the slurry pack cementation process.
