粗糙度对铜基表面PDA/PTFE涂层摩擦磨损性能的影响

Effect of roughness on friction and wear performance of PDA/PTFE coatings on copper substrate surfaces

为了改善PTFE涂层和Cu基体的界面结合性能,采用聚多巴胺(PDA)对PTFE涂层和Cu基体之间的界面进行改性,在不同粗糙度的Cu基体表面制备了PDA/PTFE自润滑涂层,利用光学轮廓仪、扫描电镜(SEM)、接触角测量仪和摩擦磨损试验机等研究了基体粗糙度对PDA改性PTFE涂层微观组织和摩擦磨损性能的影响。结果表明:PTFE涂层的成膜受到基体粗糙度和PDA分布的综合作用;当基体粗糙度R_(a)=60 nm时,基体表面粗糙峰和粗糙谷都覆盖了PTFE涂层,涂层的厚度达到最大值(约为1.83μm),此时PDA改性PTFE涂层的耐久性达到最大值(循环次数=813),涂层的磨损率最低;当基体粗糙度过大时,粗糙峰处PDA含量减少且粗糙峰处应力集中严重,容易导致PDA改性PTFE涂层的快速失效。

In order to improve the interface bonding performance between PTFE coating and Cu substrate,polydopamine(PDA)was used to modify the interface between PTFE coating and Cu substrate.Then,PDA/PTFE self-lubricating coatings were prepared on the surface of the Cu substrate with different roughness.The effect of substrate roughness on the microstructure and friction and wear properties of PDA modified PTFE coatings was studied using optical profilometer,scanning electron microscopy(SEM),contact angle measuring instrument and friction and wear testing machine.The results show that the film formation of the PTFE coatings is influenced by the combined effect of substrate roughness and PDA distribution.When the substrate roughness R_(a)=60 nm,both the rough peaks and rough valleys of the substrate surface are covered by PTFE coating,and the thickness of the coating reaches its maximum value(about 1.83μm),meanwhile,the durability of the PDA modified PTFE coating reaches the maximum value(the number of cycles=813),and the wear rate of the coating is the lowest.When the substrate roughness is too large,the PDA content at the rough peaks decreases and the stress concentration at the rough peaks is severe,which can easily lead to rapid failure of the PDA modified PTFE coatings.