A new quasi-nano wear mechanism (QNWM) has been proposed in this paper based on the facts of wear curve turning under high energy impact contact loading.Its characteristic is that the wear rate of QNWM is only 1/10-1/3 that of delamination mechanism at the same energy density.The diameters of wear debris and pits on the worn surfaces fall into the quasi-nanometer scale (about 50-120 nm).The necessary and sufficient conditions,which bring about the QNWM,are:(i) the nano-structure (nano-crystalline + amorphous phase) in impact contact surface layer has formed by the intensive impact strain;(ii) the delamination wear cracking in sub-surface layer must be restrained;(iii) the microcracks of QNWM are produced in amorphous phase of surface nano-structure layer rather than in nano-crystalline.
ZHU JinHua1,REN XiangHong1,2,ZHANG JianJun1,3,XU YunHua1,3 & LU ZhengXin1,4 1 State Key Laboratory for Mechanical Behavior of Materials,Xi’an Jiaotong University,Xi’an 710049,China
Experiments were performed on 20 different types of materials to analyze the impact contact wear and to establish the wear mechanism map. The wear mechanism has been categorized into three prominent regions(delamination wear, quasi-nano wear and lamination-like wear) and is governed by two hardness thresholds(H_(dq) and H_(ql)). When the material hardness HcpH_(ql), the mechanism is lamination-like wear; however, when H_(cp) is between Hdq and H_(ql), the mechanism is determined to be quasi-nano wear. H_(dq) is determined to be the threshold hardness between delamination wear and quasi-nano wear that reflects the cracks being produced in the subsurface layer, whereas, H_(ql) is termed threshold hardness between quasi-nano wear and lamination-like wear with formation of nanostructure within the surface layer.
