车轴钢表面渗氮／渗硫复合层的扭动微动磨损研究

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Abstract：The sulfurized-nitrided layers were prepared on the surface of LZ50 steel by sulfurized-nitri-ded duplex Drocesses.Base on the characterizations of the sulfurized-nitrided layers，the torsional fret-ting wear tests of the sulfurized-nitrided layers and LZ50 steel were carried out in dry condition underdifferent torsiona1 angular displacement amplitudes.The results indicated the sulfurized-nitrided lay-erS were composed of-Fe2 3 N，7 Fe4 N，FeS and FeS2 phases.The fretting regimes of the sulfurized-nitrided layers were changed，i.e.the range of the mixed fretting regime was diminished，and the slipregime shifted to the direction of smaller angular displacement amplitude.The friction torques of thesuIfurizednitrided layers were lower than that of the substrate in the partial slip and slip regimes dueto the support of the hard nitrided layer and the lubricating of the sulfide layer.Comparing with thesubstrate，the wear of material reduced greatly for the sulfurized-nitrided layers. The damage in thepartial slip regime was slight，but in the mixed and slip regimes the damage mechanisrns of the modi-fied layer were mainly delamination，abrasive wear and oxidative wear。

Key words：friction and wear；fretting wear；torsional fretting；sulfurized-nitrided duplex processes扭动微动是指在交变载荷下接触副接触界面发生微幅扭动的相对运动口 ]。作为微动磨损相对运动的- 种基本模式，普遍存在于机械装备中，如机车的轮轴配合面、汽车悬挂架球窝关节及机车转向架的心盘等，已成 为导致部件失效的主要原因2 ]。而表面工程技术是减缓微动损伤的重要措施之-[8 。对于接触界面而言，理想摩擦表面结构依次为较软的润滑层作为最外层，较硬的次表层支撑着表面。在离子渗氮层上进行低温离子渗硫处理得到渗氮/渗硫复合层可以有效地提高机械零件 的摩擦学性能 ]。本工作通过在 LZ50钢表面进行离子渗氮和离子渗硫复合处理，研究渗氮/渗硫复合层的扭动微动磨损性，为指导