通过同时加入Y和Ce获得了阻燃效果优异的Mg-Y-Ce阻燃镁合金,实现了镁合金在大气条件下的无保护熔炼,Mg-Y-Ce合金由工业纯Mg(99.9%,质量分数)、Mg-25%Y(质量分数)中间合金和纯Ce(99.5%,质量分数)在电阻炉中于保护性气氛(CO2+0.5%SF6)下...通过同时加入Y和Ce获得了阻燃效果优异的Mg-Y-Ce阻燃镁合金,实现了镁合金在大气条件下的无保护熔炼,Mg-Y-Ce合金由工业纯Mg(99.9%,质量分数)、Mg-25%Y(质量分数)中间合金和纯Ce(99.5%,质量分数)在电阻炉中于保护性气氛(CO2+0.5%SF6)下熔配而成。AES(PHI550 ESCA/SAM)和XRD(X’Pert Pro MPD)表面分析结果表明:当Mg-3Y-4.5Ce阻燃镁合金在高温下暴露于大气中时,其表面膜为双层膜,外层主要由Y2O3组成,而内层Y和Ce含量极低,以Mg和MgO为主。基于高温氧化热力学分析,建立了Mg-Y合金在高温下的选择性氧化模型,获得了Mg-Y合金能够发生选择性氧化的Y浓度阈值(约为7%,质量分数)。分析了Ce在Mg-Y合金选择性氧化中的第三元素效应,Ce起到了"吸气剂"的作用,可以抑制氧向合金内部扩散,从而抑制Y元素的内氧化。展开更多
Ni-CeO2 nanocomposite coatings with different CeO2 contents were prepared by codeposition of Ni and CeO2 nanoparticles with an average particle size of 7 nm onto pure Ni surfaces from a nickel sulfate. The CeO2 nanopa...Ni-CeO2 nanocomposite coatings with different CeO2 contents were prepared by codeposition of Ni and CeO2 nanoparticles with an average particle size of 7 nm onto pure Ni surfaces from a nickel sulfate. The CeO2 nanoparticles were dispersed in the electrodeposited nanocrystalline Ni grains （with a size range of 10-30 nm）. The isothermal oxidation behaviours of Ni-CeO2 nanocomposite coatings with two different CeO2 particles contents and the electrodeposited pure Ni coating were comparatively investigated in order to elucidate the effect of CeO2 at different temperatures and also CeO2 contents on the oxidation behaviour of Ni-CeO2 nanocomposite coatings. The results show that the as-codeposited Ni-CeO2 nanocomposite coatings have a superior oxidation resistance compared with the electrodeposited pure Ni coating at 800 °C due to the codeposited CeO2 nanoparticles blocking the outward diffusion of nickel along the grain boundaries. However, the effects of CeO2 particles on the oxidation resistance significantly decrease at 1050 °C and 1150 °C due to the outward-volume diffusion of nickel controlling the oxidation growth mechanism, and the content of CeO2 has little influence on the oxidation.展开更多
Three different chromizing coatings were produced on Ni substrate using a conventional pack-cementation method with Al2O3,Al2O3＋CeO2 and CeO2 acting as filler,respectively,at a greatly decreased temperature（700 ℃）...Three different chromizing coatings were produced on Ni substrate using a conventional pack-cementation method with Al2O3,Al2O3＋CeO2 and CeO2 acting as filler,respectively,at a greatly decreased temperature（700 ℃）.Effects of different fillers on the isothermal and cyclic oxidation resistance of chromizing coating in air at 850 ℃ were comparably investigated.Microstructure results show that the addition of CeO2 into the filler significantly retards the grain growth of the chromizing coating.Oxidation results indicate that the chromizing coating using CeO2 as filler exhibits somewhat increased oxidation resistance than the normal chromizmg coating,while the chromizing coating using Al2O3＋CeO2 as filler exhibits much better oxidation resistance.The effects of different fillers on the oxidation behaviors were discussed in detail.展开更多
Ni-La2O3/CeO2 composite films were prepared by electrodeposition from a nickel sulfate bath containing certain content of micrometer and nanometer La2O3/CeO2 particles. The effect of La2O3 or CeO2 particle size on the...Ni-La2O3/CeO2 composite films were prepared by electrodeposition from a nickel sulfate bath containing certain content of micrometer and nanometer La2O3/CeO2 particles. The effect of La2O3 or CeO2 particle size on the oxidation resistance of the electrodeposited Ni-La2O3/CeO2 composites in air at 1000 °C was studied. The results indicate that, compared with the electrodeposited Ni-film, Ni-La2O3/CeO2 composites exhibit a superior oxidation resistance due to the codeposited La2O3 or CeO2 particles blocking the outward diffusion of nickel. Moreover, compared with nanoparticles, La2O3 or CeO2 microparticles have stronger effect because La2O3 or CeO2 microparticles also act as a diffusion barrier layer at the onset of oxidation.展开更多
Ni3Al coatings with and without Y2O3 particles were developed by annealing the electrodeposited Ni-Al composite coatings with and without Y2O3 particles at 800 °C for 3 h. The microstructures and cyclic oxidation...Ni3Al coatings with and without Y2O3 particles were developed by annealing the electrodeposited Ni-Al composite coatings with and without Y2O3 particles at 800 °C for 3 h. The microstructures and cyclic oxidation performances of the produced Ni3Al coatings were comparatively investigated, with the emphasis on the effect of Y2O3. SEM/EDAX and TEM characterizations showed that the dispersion of Y2O3 refines the grains. Oxidation at 900 °C for 100 h showed that the addition of Y2O3 significantly improved the cyclic oxidation resistance of Ni3Al coating. The effect of Y2O3 on the microstructure and the oxidation of the Ni3Al coating were discussed in detail.展开更多
文摘通过同时加入Y和Ce获得了阻燃效果优异的Mg-Y-Ce阻燃镁合金,实现了镁合金在大气条件下的无保护熔炼,Mg-Y-Ce合金由工业纯Mg(99.9%,质量分数)、Mg-25%Y(质量分数)中间合金和纯Ce(99.5%,质量分数)在电阻炉中于保护性气氛(CO2+0.5%SF6)下熔配而成。AES(PHI550 ESCA/SAM)和XRD(X’Pert Pro MPD)表面分析结果表明:当Mg-3Y-4.5Ce阻燃镁合金在高温下暴露于大气中时,其表面膜为双层膜,外层主要由Y2O3组成,而内层Y和Ce含量极低,以Mg和MgO为主。基于高温氧化热力学分析,建立了Mg-Y合金在高温下的选择性氧化模型,获得了Mg-Y合金能够发生选择性氧化的Y浓度阈值(约为7%,质量分数)。分析了Ce在Mg-Y合金选择性氧化中的第三元素效应,Ce起到了"吸气剂"的作用,可以抑制氧向合金内部扩散,从而抑制Y元素的内氧化。
基金Project(11531319)supported by Scientific Research Fund of Heilongjiang Provincial Education Department,China
文摘Ni-CeO2 nanocomposite coatings with different CeO2 contents were prepared by codeposition of Ni and CeO2 nanoparticles with an average particle size of 7 nm onto pure Ni surfaces from a nickel sulfate. The CeO2 nanoparticles were dispersed in the electrodeposited nanocrystalline Ni grains （with a size range of 10-30 nm）. The isothermal oxidation behaviours of Ni-CeO2 nanocomposite coatings with two different CeO2 particles contents and the electrodeposited pure Ni coating were comparatively investigated in order to elucidate the effect of CeO2 at different temperatures and also CeO2 contents on the oxidation behaviour of Ni-CeO2 nanocomposite coatings. The results show that the as-codeposited Ni-CeO2 nanocomposite coatings have a superior oxidation resistance compared with the electrodeposited pure Ni coating at 800 °C due to the codeposited CeO2 nanoparticles blocking the outward diffusion of nickel along the grain boundaries. However, the effects of CeO2 particles on the oxidation resistance significantly decrease at 1050 °C and 1150 °C due to the outward-volume diffusion of nickel controlling the oxidation growth mechanism, and the content of CeO2 has little influence on the oxidation.
基金Project (11551419) supported by Scientific Research Fund of Heilongjiang Provincial Education DepartmentProject (12511469) supported by Heilongjiang Provincial Science and Technology Department
文摘Three different chromizing coatings were produced on Ni substrate using a conventional pack-cementation method with Al2O3,Al2O3＋CeO2 and CeO2 acting as filler,respectively,at a greatly decreased temperature（700 ℃）.Effects of different fillers on the isothermal and cyclic oxidation resistance of chromizing coating in air at 850 ℃ were comparably investigated.Microstructure results show that the addition of CeO2 into the filler significantly retards the grain growth of the chromizing coating.Oxidation results indicate that the chromizing coating using CeO2 as filler exhibits somewhat increased oxidation resistance than the normal chromizmg coating,while the chromizing coating using Al2O3＋CeO2 as filler exhibits much better oxidation resistance.The effects of different fillers on the oxidation behaviors were discussed in detail.
基金Project(GC13A113)supported by the Technology Research and Development Program of Heilongjiang Provincial Science and Technology DepartmentProject(12511469)supported by Heilongjiang Provincial Science and Technology Department
文摘Ni-La2O3/CeO2 composite films were prepared by electrodeposition from a nickel sulfate bath containing certain content of micrometer and nanometer La2O3/CeO2 particles. The effect of La2O3 or CeO2 particle size on the oxidation resistance of the electrodeposited Ni-La2O3/CeO2 composites in air at 1000 °C was studied. The results indicate that, compared with the electrodeposited Ni-film, Ni-La2O3/CeO2 composites exhibit a superior oxidation resistance due to the codeposited La2O3 or CeO2 particles blocking the outward diffusion of nickel. Moreover, compared with nanoparticles, La2O3 or CeO2 microparticles have stronger effect because La2O3 or CeO2 microparticles also act as a diffusion barrier layer at the onset of oxidation.
基金Project (11531319) supported by Scientific Research Fund of Heilongjiang Provincial Education Department, China
文摘Ni3Al coatings with and without Y2O3 particles were developed by annealing the electrodeposited Ni-Al composite coatings with and without Y2O3 particles at 800 °C for 3 h. The microstructures and cyclic oxidation performances of the produced Ni3Al coatings were comparatively investigated, with the emphasis on the effect of Y2O3. SEM/EDAX and TEM characterizations showed that the dispersion of Y2O3 refines the grains. Oxidation at 900 °C for 100 h showed that the addition of Y2O3 significantly improved the cyclic oxidation resistance of Ni3Al coating. The effect of Y2O3 on the microstructure and the oxidation of the Ni3Al coating were discussed in detail.
