石墨相形态对铜/石墨复合材料摩擦学性能和可靠性的影响  

Influence of Graphite Morphologies on Tribology Properties and Reliability of Copper/Graphite Composites

作　　者：张孝禹 樊恒中 黄晓鹏 胡天昌[2] 宋俊杰[2] 张永胜[2] 胡丽天[2] ZHANG Xiaoyu;FAN Hengzhong;HUANG Xiaopeng;HU Tianchang;SONG Junjie;ZHANG Yongsheng;HU Litian(College of Mechanical and Electronical Engineering,Gansu Agricultural University,Gnsu Lanzhou 730070,China;State Key Laboratory of Solid Lubrication,Lanzhou Institute of Chemical Physics,Chinese Academy of Sciences,Gansu Lanzhou 730000 China)

机构地区：[1]甘肃农业大学机电工程学院,甘肃兰州730070 [2]中国科学院兰州化学物理研究所固体润滑国家重点实验室,甘肃兰州730000

出　　处：《摩擦学学报》2022年第3期609-619,共11页Tribology

基　　金：国家自然科学基金项目(52005486);中国科学院“西部之光”人才培养计划(2017)资助。

摘　　要：采用真空热压烧结工艺制备了石墨相形态为粉体(粒径约5μm)、鳞片状(粒径445~636μm)和近球形颗粒状(粒径200~300μm)的铜/石墨复合材料,考察了以Al_(2)O_(3)陶瓷为摩擦副条件下石墨相形态对铜/石墨复合材料摩擦磨损性能及作用机制的影响,并探讨了材料在外载作用下的可靠性.结果表明:石墨相形态不同时,石墨相和金属铜在材料中的分布方式也随之改变,进而影响到材料的摩擦学性能和力学性能.在保持复合材料中石墨相含量不变的基础上,将石墨相形态从微米级粉体转变为各向异性的大块鳞片状石墨,再转变为各向同性较好的大尺寸近球形颗粒状石墨时,石墨相在材料中与金属铜形成的弱界面含量逐渐减小,金属铜的三维连续性变得更好.材料在受到外载破坏时,从石墨相与铜基体界面萌生裂纹的扩展应力可被连续金属铜及时吸收钝化,使材料抵抗裂纹破坏的能力明显提高.当石墨相为近球形颗粒状时,材料的抗弯强度、抗压强度、断裂韧性和冲击韧性分别高达155.4±3.6 MPa、353.5±24.7 MPa、5.3±0.6 MPa·m^(1/2)和4.0±0.4 J/cm^(2).此外,石墨相形态对材料的摩擦学性能也有重要影响,当石墨相以粉体形态存在时,石墨相与金属铜间形成的弱界面越多,铜基体的连续程度被石墨显著割裂,在摩擦力作用下割裂的铜颗粒易被剥离进入摩擦界面,与摩擦副形成“三体”磨损,导致材料的大量磨损.当石墨相以鳞片状形态存在时,石墨相的聚集程度相对增加,使得金属铜的连续程度相对提高,可避免发生类似复合粉体形态石墨材料的磨损.但是,鳞片状石墨呈大块片层状,形状各向异性,随着材料表面鳞片石墨的摩擦损耗,或者垂直于材料表面的鳞片石墨较多时,将造成摩擦副间摩擦系数较大的波动.当石墨相为近球形颗粒状时,较为均匀的石墨相空间分布状态、三维连续结构的铜基体和润滑相Copper/graphite composites with various of graphite morphologies containing powder(~5μm),flake graphite(445~636μm)and near spherical graphite(200~300μm)were prepared by vacuum hot pressing sintering process.The influences of the graphite morphologies on the friction-wear properties and mechanisms of copper/graphite composites coupled with Al_(2)O_(3) pin were investigated,and the reliability of the materials under loading was discussed as well.The results showed that the distribution of graphite phase and copper in the material also changed with various of graphite morphologies,which affected the tribological properties and mechanical properties of the material.On the basis of keeping the graphite phase content in the composite unchanged,when the graphite phase morphology was transformed from micron powder to large flake graphite with anisotropic structure,and then to large nearly spherical particle graphite with isotropic structure,the number of the weak interfaces formed by graphite phase and copper in the material decreased gradually,and the copper matrix became more continuous in three-dimensional space.When the graphite phase was near spherical particles,the bending strength,compressive strength,fracture toughness and impact toughness of the material were as high as 155.4±3.6 MPa、353.5±24.7 MPa、5.3±0.6 MPa·m^(1/2) and 4.0±0.4 J/cm2.In addition,the morphology of graphite phase also had a significant impact on the tribological properties of the material.When the morphology of graphite was powder,the more weak interfaces between the graphite phase and the metal copper were formed,and the continuity of the copper matrix was significantly separated by the graphite.Under the action of friction sliding,the separated copper particles could be stripped into the friction interface easily,and then forming the“threebody”wear within friction counterpart,thus resulting in a large abrasion of the material.When the graphite phase existed as flakes,the aggregation degree of the graphite phase was relatively i

关 键 词：铜/石墨复合材料 石墨形态 三维连续结构 力学性能 抗磨机制 

分 类 号：TH117.3[机械工程—机械设计及理论]