A double layer Rare Earth Metal (REM) conversion coating process of Al 6061/SiCp metal matrix composites (MMC) was studied.The corrosion resistance of REM conversion coating was examined by electrochemical impedance s...A double layer Rare Earth Metal (REM) conversion coating process of Al 6061/SiCp metal matrix composites (MMC) was studied.The corrosion resistance of REM conversion coating was examined by electrochemical impedance spectroscopy (EIS).REM conversion coating produced very corrosion resistant surface of Al 6061/SiCp MMC.The X ray diffraction (XRD) analysis revealed that REM conversion coatings exhibited non crystalline structure.The composition of REM conversion coating was studied by X ray photoelectron spectroscopy (XPS).The coatings consisted of cerium oxide and hydrated cerium oxide.Some of Ce3+were oxidized to Ce4+during the formation of the first layer coating in the solution containing Ce3+.During the course of exposing the specimens in open air,some of the residual Ce3+were oxidized to Ce4+.REM conversion coating formed in the solution containing Ce4+consisted entirely of Ce4+compounds.展开更多
To improve the surface quality for aluminum alloy 6061(Al6061) in ultra-precision machining, we investigated the factors affecting the surface finish in single point diamond turning(SPDT)by studying influence of the p...To improve the surface quality for aluminum alloy 6061(Al6061) in ultra-precision machining, we investigated the factors affecting the surface finish in single point diamond turning(SPDT)by studying influence of the precipitates generation of Al6061 on surface integrity and surface roughness.Based on the Johnson-Mehl-Avrami solid phase transformation kinetics equation, theoretical and experimental studies were conducted to build the relationship between the aging condition and the type, size and number of the precipitates for Al6061. Diamond cutting experiments were conducted to machine Al6061 samples under different aging conditions. The experimental results show that, the protruding on the chip surface is mainly Mg_(2)Si and the scratches on the machined surface mostly come from the iron-containing phase(α-, β-AlFeSi).Moreover, the generated Mg_(2)Si and α-, β-AlFeSi affect the surface integrity and the diamond turned surface roughness. Especially, the achieved surface roughness in SPDT is consistent with the variation of the number of AlFeSi and Mg_(2)Si with the medium size(more than 1 μm and less than 2 μm) in Al6061.展开更多
文摘A double layer Rare Earth Metal (REM) conversion coating process of Al 6061/SiCp metal matrix composites (MMC) was studied.The corrosion resistance of REM conversion coating was examined by electrochemical impedance spectroscopy (EIS).REM conversion coating produced very corrosion resistant surface of Al 6061/SiCp MMC.The X ray diffraction (XRD) analysis revealed that REM conversion coatings exhibited non crystalline structure.The composition of REM conversion coating was studied by X ray photoelectron spectroscopy (XPS).The coatings consisted of cerium oxide and hydrated cerium oxide.Some of Ce3+were oxidized to Ce4+during the formation of the first layer coating in the solution containing Ce3+.During the course of exposing the specimens in open air,some of the residual Ce3+were oxidized to Ce4+.REM conversion coating formed in the solution containing Ce4+consisted entirely of Ce4+compounds.
基金Funded by Natural Science Foundation of Guangdong Province,China (No.2017A030313330)Science and Technology Program of Guangzhou (No.201804020040)。
文摘To improve the surface quality for aluminum alloy 6061(Al6061) in ultra-precision machining, we investigated the factors affecting the surface finish in single point diamond turning(SPDT)by studying influence of the precipitates generation of Al6061 on surface integrity and surface roughness.Based on the Johnson-Mehl-Avrami solid phase transformation kinetics equation, theoretical and experimental studies were conducted to build the relationship between the aging condition and the type, size and number of the precipitates for Al6061. Diamond cutting experiments were conducted to machine Al6061 samples under different aging conditions. The experimental results show that, the protruding on the chip surface is mainly Mg_(2)Si and the scratches on the machined surface mostly come from the iron-containing phase(α-, β-AlFeSi).Moreover, the generated Mg_(2)Si and α-, β-AlFeSi affect the surface integrity and the diamond turned surface roughness. Especially, the achieved surface roughness in SPDT is consistent with the variation of the number of AlFeSi and Mg_(2)Si with the medium size(more than 1 μm and less than 2 μm) in Al6061.
