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
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
目的探讨舍曲林联合归因训练对脑卒中后抑郁及神经功能康复的影响。方法共78例脑卒中后抑郁患者,随机分为研究组和对照组,研究组给予舍曲林联合归因训练,对照组单用舍曲林治疗,疗程8周。在治疗前及治疗的第2、4、6、8周末用汉密尔顿抑...目的探讨舍曲林联合归因训练对脑卒中后抑郁及神经功能康复的影响。方法共78例脑卒中后抑郁患者,随机分为研究组和对照组,研究组给予舍曲林联合归因训练,对照组单用舍曲林治疗,疗程8周。在治疗前及治疗的第2、4、6、8周末用汉密尔顿抑郁量表(Hamilton depression rating scale,HAMD)和美国国立卫生研究院卒中量表(National Institute of Health stroke scale,NIHSS)分别评定抑郁症状和神经功能康复情况。结果经重复测量方差分析显示,患者HAMD总分的时间主效应、分组主效应以及时间与分组交互效应均有统计学意义(P<0.05)。其中研究组在2、4、6、8周末HAMD总分均明显低于对照组[(18.25±4.27)vs.(20.81±4.63),(15.94±3.47)vs.(18.12±4.51),(12.85±3.12)vs.(16.54±3.70),(10.42±3.66)vs.(13.09±3.59)],差异有统计学意义(P<0.05);研究组与对照组HAMD总分在各个时点均较治疗前降低(P<0.01)。治疗8周后研究组有效率(以HAMD减分率评价)高于对照组(77.5%vs.52.6%),差异有统计学意义(P<0.05)。两组NIHSS总分的时间主效应有统计学意义(P<0.01),分组主效应、时间与分组交互效应无统计学意义(P>0.05)。研究组与对照组NIHSS总分在各个时点均较治疗前降低(P<0.01)。结论舍曲林联合归因训练可明显缓解脑卒中后抑郁患者的抑郁症状,但归因训练对患者神经功能改善不明显。展开更多
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.
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.
文摘目的探讨舍曲林联合归因训练对脑卒中后抑郁及神经功能康复的影响。方法共78例脑卒中后抑郁患者,随机分为研究组和对照组,研究组给予舍曲林联合归因训练,对照组单用舍曲林治疗,疗程8周。在治疗前及治疗的第2、4、6、8周末用汉密尔顿抑郁量表(Hamilton depression rating scale,HAMD)和美国国立卫生研究院卒中量表(National Institute of Health stroke scale,NIHSS)分别评定抑郁症状和神经功能康复情况。结果经重复测量方差分析显示,患者HAMD总分的时间主效应、分组主效应以及时间与分组交互效应均有统计学意义(P<0.05)。其中研究组在2、4、6、8周末HAMD总分均明显低于对照组[(18.25±4.27)vs.(20.81±4.63),(15.94±3.47)vs.(18.12±4.51),(12.85±3.12)vs.(16.54±3.70),(10.42±3.66)vs.(13.09±3.59)],差异有统计学意义(P<0.05);研究组与对照组HAMD总分在各个时点均较治疗前降低(P<0.01)。治疗8周后研究组有效率(以HAMD减分率评价)高于对照组(77.5%vs.52.6%),差异有统计学意义(P<0.05)。两组NIHSS总分的时间主效应有统计学意义(P<0.01),分组主效应、时间与分组交互效应无统计学意义(P>0.05)。研究组与对照组NIHSS总分在各个时点均较治疗前降低(P<0.01)。结论舍曲林联合归因训练可明显缓解脑卒中后抑郁患者的抑郁症状,但归因训练对患者神经功能改善不明显。