Multiphase Fe/N nanoparticles were synthesized by means of chemical vapor reaction, the influence of the preparing parameters on the properties of particles was studied carefully dur-ing the first nitriding process. T...Multiphase Fe/N nanoparticles were synthesized by means of chemical vapor reaction, the influence of the preparing parameters on the properties of particles was studied carefully dur-ing the first nitriding process. The optimum process was determined. Single phaseγ’-Fe4N was prepared by twice-nitriding. Multiphase iron-nitride really transformsγ’-Fe4N nanoparticle of sin-gle-phase and uniform. Moreover, the mechanism of nanoparticle nucleation and growth, including phase-transformation, was revealed. In addition, the mircograph, particle size, physical phases, schemical constituents and magnetic properties before and after phase-transformation were char-acterized initially.展开更多
Plasma nitrocarburizing and plasma oxidizing treatments were performed to improve the wear and corrosion resistance of AISI 4140 steel. Plasma nitrocarburizing was conducted for 3 h at 570 ℃ in the nitrogen, hydrogen...Plasma nitrocarburizing and plasma oxidizing treatments were performed to improve the wear and corrosion resistance of AISI 4140 steel. Plasma nitrocarburizing was conducted for 3 h at 570 ℃ in the nitrogen, hydrogen and methane atmosphere to produce the ε-Fe2-3(N,C) phase. It was found that the compound layer produced by plasma nitrocarburising was predominantly composed of ε-phase, with a small proportion of γ′-Fe4(N,C) phase. The thickness of the compound layer was about 10 μm and the diffusion layer was about 300 μm in thickness, respectively. Plasma post oxidation was performed on the nitrocarburized samples with various oxygen/hydrogen ratio at a constant temperature of 500 ℃ for 1 h. The very thin magnetite (Fe3O4) layer 1-2 μm in thickness on top of the compound layer was obtained by plasma post oxidation. It was confirmed that the corrosion characteristics of the nitrocarburized compound layer can be further improved by the application of the superficial magnetite layer.展开更多
Plasma nitrocarburizing and plasma oxidizing treatments were performed to improve the wear and corrosion resistance of SKD 61 steel.Plasma nitrocarburizing was conducted for 12 h at 540℃in the nitrogen, hydrogen and ...Plasma nitrocarburizing and plasma oxidizing treatments were performed to improve the wear and corrosion resistance of SKD 61 steel.Plasma nitrocarburizing was conducted for 12 h at 540℃in the nitrogen, hydrogen and methane atmosphere to produce theε-Fe-（2-3）（N,C） phase.The compound layer produced by plasma nitrocarburising was predominantly composed ofε-phase,with a small proportion ofγ′-Fe-4 （N,C） phase. The thickness of the compound layer and the diffusion layer are about 10μm and about 200μm,respectively. Plasma post oxidation was performed on the nitrocarburized samples with various oxygen/hydrogen ratio at constant temperature of 500℃for 1 h.The very thin magnetite （Fe-3O-4） layer of 1-2μm in thickness on top of the compound layer was obtained.Anodic polarization test revealed that plasma nitrocarburizing process contributed a significant improvement of corrosion resistance of SKD 61 steel.However,the corrosion characteristics of the nitrocarburized compound layer was deteriorated by oxidation treatment.展开更多
基金supported by the China Funds of Excellent Youth and China Funds of Post Doctorthe National Natural Science Foundation of China and Post Doctor Funds of Heilongjiang Province.
文摘Multiphase Fe/N nanoparticles were synthesized by means of chemical vapor reaction, the influence of the preparing parameters on the properties of particles was studied carefully dur-ing the first nitriding process. The optimum process was determined. Single phaseγ’-Fe4N was prepared by twice-nitriding. Multiphase iron-nitride really transformsγ’-Fe4N nanoparticle of sin-gle-phase and uniform. Moreover, the mechanism of nanoparticle nucleation and growth, including phase-transformation, was revealed. In addition, the mircograph, particle size, physical phases, schemical constituents and magnetic properties before and after phase-transformation were char-acterized initially.
文摘Plasma nitrocarburizing and plasma oxidizing treatments were performed to improve the wear and corrosion resistance of AISI 4140 steel. Plasma nitrocarburizing was conducted for 3 h at 570 ℃ in the nitrogen, hydrogen and methane atmosphere to produce the ε-Fe2-3(N,C) phase. It was found that the compound layer produced by plasma nitrocarburising was predominantly composed of ε-phase, with a small proportion of γ′-Fe4(N,C) phase. The thickness of the compound layer was about 10 μm and the diffusion layer was about 300 μm in thickness, respectively. Plasma post oxidation was performed on the nitrocarburized samples with various oxygen/hydrogen ratio at a constant temperature of 500 ℃ for 1 h. The very thin magnetite (Fe3O4) layer 1-2 μm in thickness on top of the compound layer was obtained by plasma post oxidation. It was confirmed that the corrosion characteristics of the nitrocarburized compound layer can be further improved by the application of the superficial magnetite layer.
文摘Plasma nitrocarburizing and plasma oxidizing treatments were performed to improve the wear and corrosion resistance of SKD 61 steel.Plasma nitrocarburizing was conducted for 12 h at 540℃in the nitrogen, hydrogen and methane atmosphere to produce theε-Fe-（2-3）（N,C） phase.The compound layer produced by plasma nitrocarburising was predominantly composed ofε-phase,with a small proportion ofγ′-Fe-4 （N,C） phase. The thickness of the compound layer and the diffusion layer are about 10μm and about 200μm,respectively. Plasma post oxidation was performed on the nitrocarburized samples with various oxygen/hydrogen ratio at constant temperature of 500℃for 1 h.The very thin magnetite （Fe-3O-4） layer of 1-2μm in thickness on top of the compound layer was obtained.Anodic polarization test revealed that plasma nitrocarburizing process contributed a significant improvement of corrosion resistance of SKD 61 steel.However,the corrosion characteristics of the nitrocarburized compound layer was deteriorated by oxidation treatment.
