In order to improve the property of traditional Ce-based conversion coatings, Ce-silane-ZrO2 composite coatings were successfully prepared on 1060 aluminum. The microstructure, chemical element composition and corrosi...In order to improve the property of traditional Ce-based conversion coatings, Ce-silane-ZrO2 composite coatings were successfully prepared on 1060 aluminum. The microstructure, chemical element composition and corrosion resistance of Ce-based conversion coatings and Ce-silane-ZrO2 composite coatings were investigated by SEM, AFM, XPS and EIS analyses. Stacking structure of the composite coating can be observed. The inner layer of the composite coatings mainly consists of oxide and hydroxide of Ce（Ⅲ）, and the silane network is composed of the outer layer together with a small amount of Ce（Ⅳ） hydroxide. By adding silane and ZrO2 nanoparticles into Ce-based conversion coatings, the porosity and the micro cracks of the coatings decrease apparently accompanying with the improvement of the corrosion resistance.展开更多
Vacuum thermal diffusion technique was applied to preparing alloying coating on AZ31 B magnesium alloy. The microstructure and phase composition of the coatings prepared at different holding time were investigated in ...Vacuum thermal diffusion technique was applied to preparing alloying coating on AZ31 B magnesium alloy. The microstructure and phase composition of the coatings prepared at different holding time were investigated in detail using optical microscopy（OM）, scanning electron microscopy（SEM）, energy dispersive spectrometer（EDS） and X-ray diffraction（XRD）, and so on. The microhardness tester and electrochemical workstation（PS-168a） were used to measure the microhardness and corrosion resistance of the alloying coating. The results showed that the alloying coatings gradually generated with the extension of holding time under constant temperature. And the obvious bonding interface between the coating and substrate was observed, and the bonding interface was changed from smooth to zigzag. EDS and XRD analyses showed that the microstructure of alloying coating mainly consisted of eutectic α-Mg phase and continuous network β-Al（12）Mg（17） phase. The average microhardness of the coatings increased by 113% in comparison to the substrate, and the self-corrosion potential increased from-1.389 to-1.268 V at the same time.展开更多
Surface mechanical attrition treatment (SMAT) was performed on biomedicalβ-type TiNbZrFe alloy for 60 min at room temperature to study the effect of surface nanocrystallization on the corrosion resistance of TiNbZrFe...Surface mechanical attrition treatment (SMAT) was performed on biomedicalβ-type TiNbZrFe alloy for 60 min at room temperature to study the effect of surface nanocrystallization on the corrosion resistance of TiNbZrFe alloy in physiological environment. The surface nanostructure was characterized by TEM, and the electrochemical behaviors of the samples with nanocrystalline layer and coarse grain were comparatively investigated in 0.9% NaCl and 0.2% NaF solutions, respectively. The results indicate that nanocrystallines with the size of 10-30 nm are formed within the surface layer of 30 μm in depth. The nanocrystallized surface behaves higher impedance, more positive corrosion potential and lower corrosion current density in 0.9%NaCl and 0.2%NaF solutions as compared with the coarse grain surface. The improvement of the corrosion resistance is attributed to the rapid formation of stable and dense passive film on the nanocrystallized surface of TiNbZrFe alloy.展开更多
The present work focuses on a new method combining cast-infiltration with thermal spraying technology to improve the surface corrosion resistance of magnesium alloy.A zinc-based alloy layer was fabricated on the surfa...The present work focuses on a new method combining cast-infiltration with thermal spraying technology to improve the surface corrosion resistance of magnesium alloy.A zinc-based alloy layer was fabricated on the surface of AZ91D magnesium alloy. The microstructure of the layer was characterized by scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy(EDS).The phase constituent of these alloys was identified by X-ray diffractometry(XRD).The analysis results reveal that a zinc-based alloy layer with a thickness of 700μm can form on the surface of AZ91 alloy matrix.The layer is composed of Mg7Zn3,MgZn and a small amount of α-Mg solid solution.The results indicate that the corrosion-resistance of the specimen with a zinc-based alloy layer is much better than that of the specimen without the layer after being immersed in 5%NaCl solution for 240 h, and the layer is more protective for the AZ91 alloy.展开更多
Two types of composites were prepared with Al-4.5Cu alloy as a matrix using stir casting method.One was reinforced with 10wt.%of Si C and 2wt.%of MoS2.The other was reinforced with 10wt.%of Si C and 4wt.%of MoS2.Their...Two types of composites were prepared with Al-4.5Cu alloy as a matrix using stir casting method.One was reinforced with 10wt.%of Si C and 2wt.%of MoS2.The other was reinforced with 10wt.%of Si C and 4wt.%of MoS2.Their surfaces were remelted using a CO2 laser beam with an objective to study the influence of laser surface melting(LSM).The topography,microhardness,corrosion resistance and wear resistance of the laser melted surfaces were studied.Overall surface integrity after LSM was compared with as-cast surface.LSM enhanced the microhardness and wear resistance of the surface in each case.Porosity of the laser melted surface was low and corrosion resistance was high.Thus,LSM can be conveniently applied to enhancing the surface integrity of the aluminium composites.However,there is an optimum laser specific energy,around 38 J/m^2 in this study,for obtaining the best surface integrity.展开更多
Oxide coatings were prepared on magnesium alloys in electrolyte solution of Na2SiO3 at different current densities(3,4 and 5 A/cm 2 )with micro-arc oxidation process.X-ray diffractometry(XRD)results show that the oxid...Oxide coatings were prepared on magnesium alloys in electrolyte solution of Na2SiO3 at different current densities(3,4 and 5 A/cm 2 )with micro-arc oxidation process.X-ray diffractometry(XRD)results show that the oxide coatings formed on magnesium alloys are mainly composed of MgO and MgAl2O4 phases;in addition,the content of MgO increases with increasing the current density.The morphology and surface roughness of the coatings were characterized by confocal laser scanning microscopy (CLSM).The results show that the surface roughness(Ra)decreases with increasing the current density.Moreover,the electrochemical corrosion results prove that the MgO coating produced in the electrolyte Na2SiO3 at current density of 5 A/cm 2 shows the best corrosion resistance.展开更多
The alloy （AI-Cu-Mg） alloy important one dating back to the series （2xxx） where copper foundries basic element which represents the number （2）, the study relied on foundries add elements boron （B） and titanium...The alloy （AI-Cu-Mg） alloy important one dating back to the series （2xxx） where copper foundries basic element which represents the number （2）, the study relied on foundries add elements boron （B） and titanium （Ti） and then use a heat treatment （homogenizing process） to improve the corrosion resistance in saline （NaC1 3.5%） of the base alloy （A1-Cu-Mg）, was prepared four types of alloys （A, B, C, D） depending on the chemical composition. The results showed that the corrosion resistance in saline solution was the best resistance in the alloy （D） （A1-2% Cu-2% Mg-0.1% B-1.0% Ti） compared with the rest of bullion when an examination of corrosion of the alloy prepared after homogenizing. But by examining the surface roughness of the alloy ingot turned out that （D） is softer than the rest of the surface alloys and this is due to the addition of boron and titanium together increases surface smoothness in alloys because it works to reduce the grain size.展开更多
Liquid nitriding of Cll0 steel was conducted in a wide range of temperatures （400-670 ℃） using a kind of chemical heat-treatments, and the hardness, mechanical and corrosion properties of the nitrided surface were ...Liquid nitriding of Cll0 steel was conducted in a wide range of temperatures （400-670 ℃） using a kind of chemical heat-treatments, and the hardness, mechanical and corrosion properties of the nitrided surface were evaluated. Experimental results revealed that the microstructure and phase constituents of the nitrided surface alloy are highly depended on the processing condition. When C 110 steel was subjected to liquid nitriding at 430 ℃, the nitrided layer was almost composed of a thin e-Fe2-3N layer. When C 110 steel was subjected to liquid nitriding at 640 ℃, the phase composition of the nitrided layer was greatly changed. The nitrided layer depth increased significantly with increasing the treating temperature. The liquid nitriding effectively improved the surface hardness. After liquid nitriding, the absorption energy of the treated sample decreased and the tensile strength increased by Charpy V-notch （CVN） test. But the elongation of treated sample decreased. The reason is that the nitrided layer of sample is hardened and there is brittlement by diffusion of nitrogen atom. Despite of treatment temperature, the liquid nitriding can improve the corrosion. After being nitrided at 430 ℃, the nitrided layer of the C110 steel was mainly composed by e-Fe2 3N, which has excellent corrosion resistance and high microhardness, the nitrided sample has the best corrosion resistance. After nitriding temperature over 580 ℃, especially at 680 ℃, the sample＇s surface was covered by the thick oxide layer, which has very low hardness and corrosion resistance. So, the corrosion resistance of samples is severely compromised.展开更多
The corrosion resistance and cytocompatibility of Ti-20 Zr-10 Nb-4 Ta（TZNT） alloy modified by surface laser treatment were investigated. The scanning electron microscopy（SEM） measurements indicated that laser trea...The corrosion resistance and cytocompatibility of Ti-20 Zr-10 Nb-4 Ta（TZNT） alloy modified by surface laser treatment were investigated. The scanning electron microscopy（SEM） measurements indicated that laser treatment on TZNT alloy generated groove morphologies with the width of^40 μm and the depth of ~10 μm on the surface. The water contact angles along the groove direction decreased by 51%compared with that of the untreated alloy. The laser treatment promoted the oxidation of metallic Ti, Zr and Nb and produced more stable oxides on surface. The corrosion potential increased by 50% and corrosion current density decreased by72% compared with that of the untreated alloy in the anodic polarization test for the alloy in Hank’s solution at 37°C. This indicated the improvement of the corrosion resistance by laser treatment. The cytotoxicity testing results showed that the laser-treated TZNT alloy performed similar MC3 T3-E1 cell viability compared with the untreated alloy. The cells displayed oriented growth along the groove direction due to the increased hydrophilicity. This novel material may be a new candidate in orthopedics and dentistry implantations fields.展开更多
基金Project(51172217)supported by the National Natural Science Foundation of ChinaProject(2010GGX10310)supported by Shandong Science and Technology Program,China+1 种基金Project(10-3-4-1-jch)supported by Science and Technology Program on Basic Research Project of Qingdao,ChinaProject(4500-841313001)supported by Fundamental Research Funds for the Central Universities,China
文摘In order to improve the property of traditional Ce-based conversion coatings, Ce-silane-ZrO2 composite coatings were successfully prepared on 1060 aluminum. The microstructure, chemical element composition and corrosion resistance of Ce-based conversion coatings and Ce-silane-ZrO2 composite coatings were investigated by SEM, AFM, XPS and EIS analyses. Stacking structure of the composite coating can be observed. The inner layer of the composite coatings mainly consists of oxide and hydroxide of Ce（Ⅲ）, and the silane network is composed of the outer layer together with a small amount of Ce（Ⅳ） hydroxide. By adding silane and ZrO2 nanoparticles into Ce-based conversion coatings, the porosity and the micro cracks of the coatings decrease apparently accompanying with the improvement of the corrosion resistance.
基金Project(2015GY167)supported by the Science and Technology Department of Shaanxi Province,ChinaProject(2014cxy-05-1)supported by the Science and Technology Bureau of Yulin,China
文摘Vacuum thermal diffusion technique was applied to preparing alloying coating on AZ31 B magnesium alloy. The microstructure and phase composition of the coatings prepared at different holding time were investigated in detail using optical microscopy（OM）, scanning electron microscopy（SEM）, energy dispersive spectrometer（EDS） and X-ray diffraction（XRD）, and so on. The microhardness tester and electrochemical workstation（PS-168a） were used to measure the microhardness and corrosion resistance of the alloying coating. The results showed that the alloying coatings gradually generated with the extension of holding time under constant temperature. And the obvious bonding interface between the coating and substrate was observed, and the bonding interface was changed from smooth to zigzag. EDS and XRD analyses showed that the microstructure of alloying coating mainly consisted of eutectic α-Mg phase and continuous network β-Al（12）Mg（17） phase. The average microhardness of the coatings increased by 113% in comparison to the substrate, and the self-corrosion potential increased from-1.389 to-1.268 V at the same time.
基金Projects(N100702001,N120310001)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(20131036)supported by Doctoral Fund of Liaoning Province,ChinaProject(51301037)supported by the National Natural Science Foundation of China
文摘Surface mechanical attrition treatment (SMAT) was performed on biomedicalβ-type TiNbZrFe alloy for 60 min at room temperature to study the effect of surface nanocrystallization on the corrosion resistance of TiNbZrFe alloy in physiological environment. The surface nanostructure was characterized by TEM, and the electrochemical behaviors of the samples with nanocrystalline layer and coarse grain were comparatively investigated in 0.9% NaCl and 0.2% NaF solutions, respectively. The results indicate that nanocrystallines with the size of 10-30 nm are formed within the surface layer of 30 μm in depth. The nanocrystallized surface behaves higher impedance, more positive corrosion potential and lower corrosion current density in 0.9%NaCl and 0.2%NaF solutions as compared with the coarse grain surface. The improvement of the corrosion resistance is attributed to the rapid formation of stable and dense passive film on the nanocrystallized surface of TiNbZrFe alloy.
文摘The present work focuses on a new method combining cast-infiltration with thermal spraying technology to improve the surface corrosion resistance of magnesium alloy.A zinc-based alloy layer was fabricated on the surface of AZ91D magnesium alloy. The microstructure of the layer was characterized by scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy(EDS).The phase constituent of these alloys was identified by X-ray diffractometry(XRD).The analysis results reveal that a zinc-based alloy layer with a thickness of 700μm can form on the surface of AZ91 alloy matrix.The layer is composed of Mg7Zn3,MgZn and a small amount of α-Mg solid solution.The results indicate that the corrosion-resistance of the specimen with a zinc-based alloy layer is much better than that of the specimen without the layer after being immersed in 5%NaCl solution for 240 h, and the layer is more protective for the AZ91 alloy.
文摘Two types of composites were prepared with Al-4.5Cu alloy as a matrix using stir casting method.One was reinforced with 10wt.%of Si C and 2wt.%of MoS2.The other was reinforced with 10wt.%of Si C and 4wt.%of MoS2.Their surfaces were remelted using a CO2 laser beam with an objective to study the influence of laser surface melting(LSM).The topography,microhardness,corrosion resistance and wear resistance of the laser melted surfaces were studied.Overall surface integrity after LSM was compared with as-cast surface.LSM enhanced the microhardness and wear resistance of the surface in each case.Porosity of the laser melted surface was low and corrosion resistance was high.Thus,LSM can be conveniently applied to enhancing the surface integrity of the aluminium composites.However,there is an optimum laser specific energy,around 38 J/m^2 in this study,for obtaining the best surface integrity.
基金Project(20080505)supported by Science and Technology Department of Jilin Province,China
文摘Oxide coatings were prepared on magnesium alloys in electrolyte solution of Na2SiO3 at different current densities(3,4 and 5 A/cm 2 )with micro-arc oxidation process.X-ray diffractometry(XRD)results show that the oxide coatings formed on magnesium alloys are mainly composed of MgO and MgAl2O4 phases;in addition,the content of MgO increases with increasing the current density.The morphology and surface roughness of the coatings were characterized by confocal laser scanning microscopy (CLSM).The results show that the surface roughness(Ra)decreases with increasing the current density.Moreover,the electrochemical corrosion results prove that the MgO coating produced in the electrolyte Na2SiO3 at current density of 5 A/cm 2 shows the best corrosion resistance.
文摘The alloy （AI-Cu-Mg） alloy important one dating back to the series （2xxx） where copper foundries basic element which represents the number （2）, the study relied on foundries add elements boron （B） and titanium （Ti） and then use a heat treatment （homogenizing process） to improve the corrosion resistance in saline （NaC1 3.5%） of the base alloy （A1-Cu-Mg）, was prepared four types of alloys （A, B, C, D） depending on the chemical composition. The results showed that the corrosion resistance in saline solution was the best resistance in the alloy （D） （A1-2% Cu-2% Mg-0.1% B-1.0% Ti） compared with the rest of bullion when an examination of corrosion of the alloy prepared after homogenizing. But by examining the surface roughness of the alloy ingot turned out that （D） is softer than the rest of the surface alloys and this is due to the addition of boron and titanium together increases surface smoothness in alloys because it works to reduce the grain size.
基金Projects(51471112,51611130204)supported by the National Natural Science Foundation of China
文摘Liquid nitriding of Cll0 steel was conducted in a wide range of temperatures （400-670 ℃） using a kind of chemical heat-treatments, and the hardness, mechanical and corrosion properties of the nitrided surface were evaluated. Experimental results revealed that the microstructure and phase constituents of the nitrided surface alloy are highly depended on the processing condition. When C 110 steel was subjected to liquid nitriding at 430 ℃, the nitrided layer was almost composed of a thin e-Fe2-3N layer. When C 110 steel was subjected to liquid nitriding at 640 ℃, the phase composition of the nitrided layer was greatly changed. The nitrided layer depth increased significantly with increasing the treating temperature. The liquid nitriding effectively improved the surface hardness. After liquid nitriding, the absorption energy of the treated sample decreased and the tensile strength increased by Charpy V-notch （CVN） test. But the elongation of treated sample decreased. The reason is that the nitrided layer of sample is hardened and there is brittlement by diffusion of nitrogen atom. Despite of treatment temperature, the liquid nitriding can improve the corrosion. After being nitrided at 430 ℃, the nitrided layer of the C110 steel was mainly composed by e-Fe2 3N, which has excellent corrosion resistance and high microhardness, the nitrided sample has the best corrosion resistance. After nitriding temperature over 580 ℃, especially at 680 ℃, the sample＇s surface was covered by the thick oxide layer, which has very low hardness and corrosion resistance. So, the corrosion resistance of samples is severely compromised.
基金supported by the National Natural Science Foundation of China (NSFC, 51771011)the Fundamental Research Funds for the Central Universities (KG12002601)
文摘The corrosion resistance and cytocompatibility of Ti-20 Zr-10 Nb-4 Ta（TZNT） alloy modified by surface laser treatment were investigated. The scanning electron microscopy（SEM） measurements indicated that laser treatment on TZNT alloy generated groove morphologies with the width of^40 μm and the depth of ~10 μm on the surface. The water contact angles along the groove direction decreased by 51%compared with that of the untreated alloy. The laser treatment promoted the oxidation of metallic Ti, Zr and Nb and produced more stable oxides on surface. The corrosion potential increased by 50% and corrosion current density decreased by72% compared with that of the untreated alloy in the anodic polarization test for the alloy in Hank’s solution at 37°C. This indicated the improvement of the corrosion resistance by laser treatment. The cytotoxicity testing results showed that the laser-treated TZNT alloy performed similar MC3 T3-E1 cell viability compared with the untreated alloy. The cells displayed oriented growth along the groove direction due to the increased hydrophilicity. This novel material may be a new candidate in orthopedics and dentistry implantations fields.
