滚压诱导梯度超细晶铜的润滑微动磨损特性研究  

Lubricated Fretting Wear of Gradient Ultrafine-Grained Copper Induced by Burnishing

作　　者：李宁[1] 夏伟[1] 赵婧[1] 李风雷[1] 唐正强[2] 

机构地区：[1]华南理工大学机械与汽车工程学院,广东广州510640 [2]美国加州大学圣地亚哥分校磁记录研究中心,拉霍亚ca92093

出　　处：《摩擦学学报》2014年第1期20-27,共8页Tribology

基　　金：国家自然科学基金(50975095);中央高校基础研究基金(2012ZM0048)资助~~

摘　　要：通过滚柱对纯铜表面进行大载荷的多次滚压,使其表层累积不同应变水平的塑性变形,对所形成的约150μm的塑性变形层沿深度方向的晶粒形态和分布进行分析,并对其显微硬度进行测试,表明该工艺在纯铜表层诱导形成了一种梯度超细晶结构;最表层平均晶粒尺寸约为662 nm,并随深度逐渐增至基体晶粒尺寸94μm;梯度超细晶铜(简称梯度铜)最表层硬度较基体硬度提高约45%,并随深度逐渐下降至基体硬度.在SRV IV试验机上对梯度铜和粗晶铜在润滑条件下的微动磨损特性进行对比研究.结果表明:梯度铜摩擦系数先减小后增大,并在大载荷下与粗晶铜趋于一致;梯度铜的主要磨损形式为磨粒磨损,而粗晶铜为磨粒磨损和疲劳剥落,部分区域出现氧化磨损;梯度铜抗微动磨损能力比粗晶铜提高10倍以上.The surface of pure copper was repeatedly burnished by rollers using large loads, introducing the plastic deformation with different strain levels into the surface layer. The microstructure and grain distributions of a plastic deformation surface layer with the thickness of 150 μm at different depths were analyzed, and the microhardness was also measured. The results show that, a gradient uhrafine - grained （GUG） structure was induced on the surface layer of copper. The average grain size increased from 662 nm in the topmost surface to 94μm in the matrix with the increasing depth. The hardness of the topmost surface increased by 45% than that of the matrix and gradually decreased with the increase of depth. The fretting wear properties of GUG Cu and the coarse - grained （CG） Cu were investigated at the SRV IV tribo - meter at room temperature. The results indicate that the friction coefficients of GUG Cu first decreased and then increased, which were consistent with that of CG Cu under large loads. The wear mechanism of GUG Cu was mainly abrasive wear but the main wear forms of CG Cu were abrasive wear and fatigue spalling accompanied by oxidation wear in some regions. The fretting wears resistance of GUG Cu increased by more than 10 times than that of CG Cu.

关 键 词：滚压 梯度结构 超细晶 微动磨损 

分 类 号：TH117.1[机械工程—机械设计及理论]