表面光洁度对氧化处理工业纯锆干磨损行为的影响

摘要

研究在干磨条件下表面光洁度对氧化处理工业纯锆(CP-Zr)摩擦磨损性能的影响.CP-Zr试样经表面打磨后(Ra=0.21 μm),在650℃氧化6h.氧化后,部分试样经过抛光而取得镜面光洁度(Ra=0.04 μm).采用单向滑动试验对抛光和未抛光的氧化试样进行比较测试.结果 表明,表面抛光对氧化CP-Zr的干摩擦磨损性能有较大的影响,包括磨擦因数、磨损速率、裂纹形成和氧化层破裂.表面抛光加快在干磨擦过程中半圆形裂纹的形成和氧化层的破裂.在高接触应力下,稍微粗造的氧化表面有利于减缓裂纹的形成和耐磨性的提高.并对磨损机理,包括裂纹形成、扩展和断裂进行探讨.%The effect of surface polishing on the wear behavior of thermally oxidized commercial pure zirconium (CP-Zr) under dry sliding conditions was investigated.Surface ground CP-Zr with a roughness of 0.21 μm (Ra) was thermally oxidized (TO) at 650 ℃ for 6 h.After TO,some samples were polished to smoothen the surface with a finish of 0.04 μmn (Ra).The response of the polished and unpolished TO samples to dry sliding wear was investigated under unidirectional sliding conditions.The results show that surface polishing after TO affects the dry sliding wear behavior of TO CP-Zr in several aspects,including coefficient of friction,wear rate,crack formation and oxide layer breakdown.In particular,it is found that smoothening the TO surface favors the formation of semi-circular cracks in the wear track and accelerates oxide layer breakdown during dry sliding.A slightly rough TO surface helps to reduce the tendency of the oxide layer towards cracking and to increase the wear resistance at high contact loads.The mechanisms involved are discussed in terms of asperity contacts,crack formation,propagation and final fracture.