A phosphate solution free of chromate, fluoride and nitrite was prepared and an environment-friendly film was obtained on AZ31 magnesium alloy surface via the chemical deposition method. The morphology, composition, p...A phosphate solution free of chromate, fluoride and nitrite was prepared and an environment-friendly film was obtained on AZ31 magnesium alloy surface via the chemical deposition method. The morphology, composition, phase structure and its corrosion resistance were studied. The effects of film-forming temperature and free acid on corrosion resistance, microstructure and electrochemical behavior of the film were discussed. The results indicate that the corrosion resistance of AZ31 with the phosphate film was better than blank AZ31 substrate, which was most attributed to the great inhibitive action on the anodic dissolution and cathodic hydrogen evolution of the film.展开更多
TiO2 mesocrystals can considerably enhance charge separation owing to their oriented superstructures,with fewer internal defects and porous properties providing more active sites.In this work,we prepared TiO2 mesocrys...TiO2 mesocrystals can considerably enhance charge separation owing to their oriented superstructures,with fewer internal defects and porous properties providing more active sites.In this work,we prepared TiO2 mesocrystal films by a direct annealing method.The morphology and crystal phase of the film were controlled by adjusting the ratio of NH4F and the calcination temperature.Moreover,we found that Au nanoparticles loaded on a TiO2 mesocrystal film enabled highly efficient visible light photocatalytic properties.The photocatalytic activities were studied by hydrogen generation and photoreduction of Cr(VI).This work represents a considerable advance in the development and application of the TiO2 mesocrystals.展开更多
The cerium conversion film was applied to improving the corrosion resistance of Mg-Gd-Y-Zr magnesium alloy. The film was electrodeposited on the surface of the Mg-RE alloy in cerium nitrate solution. The compositions ...The cerium conversion film was applied to improving the corrosion resistance of Mg-Gd-Y-Zr magnesium alloy. The film was electrodeposited on the surface of the Mg-RE alloy in cerium nitrate solution. The compositions and morphologies were analyzed by X-ray diffraction(XRD), scanning election microscopy (SEM). The corrosion behaviors of the film were investigated electrochemical impedance spectroscopy (EIS), potentiodynamic polarization tests and immersion tests. The results show that the optimum parameters for electrochemical deposition are as follows: pH 10.0, time 30 min, 50 mmol/L Na2CO3 and temperature 25 ℃ by the designed experiments according to the orthogonal table L(9, 34). The corrosion protection efficiency is dependent on the deposition parameters. The cerium conversion film shows better corrosion protection behavior than chromate conversion film on Mg-Gd-Y-Zr magnesium alloy.展开更多
Applying negative bias voltages caused significant microstructure changes in arc ion plated CrN films. Nanocrystalline microstructures were obtained by adjusting the negative bias voltage. Structural characterizations...Applying negative bias voltages caused significant microstructure changes in arc ion plated CrN films. Nanocrystalline microstructures were obtained by adjusting the negative bias voltage. Structural characterizations of the films were carried out using X-ray diffractometry (XRD) and high-resolution transmission electron microscopy (HR-TEM). The results indicated that increasing ion bombardment by applying negative bias voltages resulted in the formation of defects in the CrN films, inducing microstructure evolution from micro-columnar to nanocrystalline. The microhardness and residual stresses of the films were also affected. Based on the experimental results, the evolution mechanisms of the film microstructure and properties were discussed by considering ion bombardment effects.展开更多
An organic-magnesium complex conversion(OMCC)coating on AZ91D magnesium alloy was obtained by treating in a solution containing organic compounds.SEM,FESEM and XPS were used to examine the surface morphology,thickness...An organic-magnesium complex conversion(OMCC)coating on AZ91D magnesium alloy was obtained by treating in a solution containing organic compounds.SEM,FESEM and XPS were used to examine the surface morphology,thickness and structure of the conversion coatings.The results show that the continuous and uniform conversion coating is deposited on AZ91D alloy and the main component of the coatings is organic compound containing benzene ring,which forms a chemical bond with magnesium.The polarization measurement and salt spray test show that the corrosion resistance of the conversion coating is much higher than that of traditional chromate conversion coating.展开更多
An ODS （oxide dispersion strengthened） steels are one of the most notable structural materials being developed for future high-temperature energy production technologies, and several studies have been devoted to the...An ODS （oxide dispersion strengthened） steels are one of the most notable structural materials being developed for future high-temperature energy production technologies, and several studies have been devoted to the development of ODS materials for such applications. However, only little paper focuses on corrosion behavior of F/M （ferritic martensictic） and ODS steels. The corrosion behavior of 11% Cr F/M steel and 15% Cr ODS steel were evaluated using electrochemical methods in borate buffer and 1 kmol m＂3 HNO3 with or without NaCI and also in boiling 60% nitric acid. The corrosion resistance results clearly indicated the influences of steel alloys composition and chloride ions. The XPS （X-ray photo-electron spectroscopy） results of the pre-passivated surface revealed that the oxide formed were composed predominantly of Fe203 along with Cr203, and Y203 layers in ODS steel. The corrosion rate measured in boiling nitric acid for 48 h for both the steels shows high corrosion rate in boiling condition. The SEM （scanning electron microscopy） observation of the pit morphology after corrosion tests appears with shallow pit in both steel surfaces The corrosion degradation behavior in relation to the composition of the passive oxide film in different electrolytic solutions is discussed in this paper.展开更多
Photocatalytic reduction of hexavalent chromium in wastewater has been widely investigated as an attractive treatment method. In this work, we reported an efficient method for photocatalytic reduction of Cr（VI） over...Photocatalytic reduction of hexavalent chromium in wastewater has been widely investigated as an attractive treatment method. In this work, we reported an efficient method for photocatalytic reduction of Cr（VI） over transparent polyvinyl alcohol/titanium dioxide （PVA/TiO2） nanocomposite films under sunlight irradiation. The trans- parent PVA/TiO2 nanocomposite films were prepared by a simple hydrothermal method combined with a solution casting process. The results revealed that the anatase TiO2 nanoparticles with size less than 10 nm were in-situ generated in PVA matrix, which endowed the films with high trans- parency. Photocatalytic reduction of Cr（VI） over PVA/TiO2 nanocomposite films exhibited superior visible light pho- tocatalytic activity. Mechanism investigation demonstrated that the PVA acted not only as a transparent support for TiO2 nanoparticles, but also as holes scavengers simultaneously to improve the separation of photogenerated holes and elec- trons. Meanwhile, the transparent PVA/TiO2 nanocomposite films displayed remarkable stability and excellent recyclabil- ity during multicycle Cr（VI） photoreduction. Furthermore, the PVA/TiO2 nanocomposite films showed selective adsorp- tion ability for Cr（III）, and thus totally removal of Cr（VI） was achieved after photoreduction process.展开更多
基金Projects (2011CL08, 2011CL01) supported by Open Fund of Material Corrosion and Protection Key Laboratory of Sichuan Province, ChinaProject (2011RC02) supported by Talent Introduction Funds of Sichuan University of ScienceProject (12ZA261) supported by Key Project of Education Department of Sichuan Province, China
文摘A phosphate solution free of chromate, fluoride and nitrite was prepared and an environment-friendly film was obtained on AZ31 magnesium alloy surface via the chemical deposition method. The morphology, composition, phase structure and its corrosion resistance were studied. The effects of film-forming temperature and free acid on corrosion resistance, microstructure and electrochemical behavior of the film were discussed. The results indicate that the corrosion resistance of AZ31 with the phosphate film was better than blank AZ31 substrate, which was most attributed to the great inhibitive action on the anodic dissolution and cathodic hydrogen evolution of the film.
文摘TiO2 mesocrystals can considerably enhance charge separation owing to their oriented superstructures,with fewer internal defects and porous properties providing more active sites.In this work,we prepared TiO2 mesocrystal films by a direct annealing method.The morphology and crystal phase of the film were controlled by adjusting the ratio of NH4F and the calcination temperature.Moreover,we found that Au nanoparticles loaded on a TiO2 mesocrystal film enabled highly efficient visible light photocatalytic properties.The photocatalytic activities were studied by hydrogen generation and photoreduction of Cr(VI).This work represents a considerable advance in the development and application of the TiO2 mesocrystals.
基金Project (5133001E) supported by the Major State Basic Research and Development Program of China
文摘The cerium conversion film was applied to improving the corrosion resistance of Mg-Gd-Y-Zr magnesium alloy. The film was electrodeposited on the surface of the Mg-RE alloy in cerium nitrate solution. The compositions and morphologies were analyzed by X-ray diffraction(XRD), scanning election microscopy (SEM). The corrosion behaviors of the film were investigated electrochemical impedance spectroscopy (EIS), potentiodynamic polarization tests and immersion tests. The results show that the optimum parameters for electrochemical deposition are as follows: pH 10.0, time 30 min, 50 mmol/L Na2CO3 and temperature 25 ℃ by the designed experiments according to the orthogonal table L(9, 34). The corrosion protection efficiency is dependent on the deposition parameters. The cerium conversion film shows better corrosion protection behavior than chromate conversion film on Mg-Gd-Y-Zr magnesium alloy.
基金Project(2010-0001-226) supported by the National Core Research Center (NCRC) Program through the National Research Foundation of Korea funded by the Ministry of Education, Science and TechnologyProject supported by the Fundamental R&D Program for Core Technology of Materials funded by the Ministry of Knowledge Economy, Korea
文摘Applying negative bias voltages caused significant microstructure changes in arc ion plated CrN films. Nanocrystalline microstructures were obtained by adjusting the negative bias voltage. Structural characterizations of the films were carried out using X-ray diffractometry (XRD) and high-resolution transmission electron microscopy (HR-TEM). The results indicated that increasing ion bombardment by applying negative bias voltages resulted in the formation of defects in the CrN films, inducing microstructure evolution from micro-columnar to nanocrystalline. The microhardness and residual stresses of the films were also affected. Based on the experimental results, the evolution mechanisms of the film microstructure and properties were discussed by considering ion bombardment effects.
基金Project(50871046)supported by the National Natural Science Foundation of ChinaProject(2007KZ09)supported by the 2007 Scienceand Technology Support Plan of Changchun City,China
文摘An organic-magnesium complex conversion(OMCC)coating on AZ91D magnesium alloy was obtained by treating in a solution containing organic compounds.SEM,FESEM and XPS were used to examine the surface morphology,thickness and structure of the conversion coatings.The results show that the continuous and uniform conversion coating is deposited on AZ91D alloy and the main component of the coatings is organic compound containing benzene ring,which forms a chemical bond with magnesium.The polarization measurement and salt spray test show that the corrosion resistance of the conversion coating is much higher than that of traditional chromate conversion coating.
文摘An ODS （oxide dispersion strengthened） steels are one of the most notable structural materials being developed for future high-temperature energy production technologies, and several studies have been devoted to the development of ODS materials for such applications. However, only little paper focuses on corrosion behavior of F/M （ferritic martensictic） and ODS steels. The corrosion behavior of 11% Cr F/M steel and 15% Cr ODS steel were evaluated using electrochemical methods in borate buffer and 1 kmol m＂3 HNO3 with or without NaCI and also in boiling 60% nitric acid. The corrosion resistance results clearly indicated the influences of steel alloys composition and chloride ions. The XPS （X-ray photo-electron spectroscopy） results of the pre-passivated surface revealed that the oxide formed were composed predominantly of Fe203 along with Cr203, and Y203 layers in ODS steel. The corrosion rate measured in boiling nitric acid for 48 h for both the steels shows high corrosion rate in boiling condition. The SEM （scanning electron microscopy） observation of the pit morphology after corrosion tests appears with shallow pit in both steel surfaces The corrosion degradation behavior in relation to the composition of the passive oxide film in different electrolytic solutions is discussed in this paper.
基金supported by the Joint Program of Beijing Natural Science Foundation and Beijing Academy of Science and Technology (L140005)the National Natural Science Foundation of China (51203094)
文摘Photocatalytic reduction of hexavalent chromium in wastewater has been widely investigated as an attractive treatment method. In this work, we reported an efficient method for photocatalytic reduction of Cr（VI） over transparent polyvinyl alcohol/titanium dioxide （PVA/TiO2） nanocomposite films under sunlight irradiation. The trans- parent PVA/TiO2 nanocomposite films were prepared by a simple hydrothermal method combined with a solution casting process. The results revealed that the anatase TiO2 nanoparticles with size less than 10 nm were in-situ generated in PVA matrix, which endowed the films with high trans- parency. Photocatalytic reduction of Cr（VI） over PVA/TiO2 nanocomposite films exhibited superior visible light pho- tocatalytic activity. Mechanism investigation demonstrated that the PVA acted not only as a transparent support for TiO2 nanoparticles, but also as holes scavengers simultaneously to improve the separation of photogenerated holes and elec- trons. Meanwhile, the transparent PVA/TiO2 nanocomposite films displayed remarkable stability and excellent recyclabil- ity during multicycle Cr（VI） photoreduction. Furthermore, the PVA/TiO2 nanocomposite films showed selective adsorp- tion ability for Cr（III）, and thus totally removal of Cr（VI） was achieved after photoreduction process.
