膨胀石墨对磷铜纤维电刷载流摩擦学性能的影响  

Effects of expanded graphite on the current carrying tribological properties of phosphor-bronze fiber brush

作　　者：罗博 经贵如 李长江 张雷[1] LUO Bo;JING Guiru;LI Changjiang;ZHANG Lei(State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083,China;Aerospace System Engineering Shanghai,Shanghai 201109,China)

机构地区：[1]中南大学粉末冶金国家重点实验室,长沙410083 [2]上海宇航系统工程研究所,上海201109

出　　处：《粉末冶金材料科学与工程》2018年第2期147-156,共10页Materials Science and Engineering of Powder Metallurgy

基　　金：国家自然科学基金资助项目(51674304)

摘　　要：采用直径50μm的磷铜纤维作为主体材料,用膨胀石墨纸作润滑组元,用石墨纸包覆纤维束制备磷铜纤维电刷,研究石墨含量对电刷电接触性能及载流摩擦磨损性能的影响。结果表明,通过将纤维进行弯曲处理构建金属纤维均匀分散的三维网状刷体结构,可使电刷具有较低弹性系数的同时保持一定的抗压强度,在17.5%的纤维填充率(体积分数)下,弯曲纤维电刷比未弯曲纤维电刷具有略高的抗压强度(分别为2.69和2.62 MPa)和更低的弹性系数(分别为149.5和428.8 N/mm)。膨胀石墨在改善磷铜纤维电刷摩擦磨损性能的同时,降低电刷的电接触性能,随膨胀石墨的体积分数从6.2%增至29.1%,电刷的摩擦因数由0.67降至0.25,接触电压降由244.86 mV升至427.81 mV。此外,石墨的润滑作用可有效改善磷铜纤维电刷的不对称磨损状态,在无石墨润滑条件下,电刷阴阳两极的磨损率分别为5.83×10^(-9) m/m和1.12×10^(-8) m/m,膨胀石墨含量为29.1%时,阴阳两极的磨损率分别降至0.44×10^(-9)和0.53×10^(-9) m/m,并且两极的磨损率差异显著减小。A fiber brush was prepared by rolling the fiber bundle with expanded graphite paper using phosphor-bronze fibers with diameter of 50μm as the main material and expanded graphite paper as the lubricant.The effects of expanded graphite content on the electric contact property and current carrying tribological properties of the fiber brush were studied.The results show that,a three-dimensional brush structure with uniform dispersion of fibers was constructed through bending the phosphor-bronze fibers,which leads to a lower elastic constant and appropriate compression strength of the fiber brush.The bent phosphor-bronze fiber brush,compared to the unbent phosphor-bronze fiber brush with the same packing fraction of fiber(17.5%),possesses slightly higher compressive strength(2.69 MPa vs 2.62 MPa)and lower elastic constants(149.5 N/mm vs 428.8 N/mm).The friction and wear properties of the brushes increase while the electrical contact property decreases.With the content of expanded graphite increasing from 6.2%to 29.1%,the friction coefficient decreases from 0.67 to 0.25,and the contact voltage drop increases from 244.86 mV to 427.81 mV.Otherwise,the asymmetric wear behavior of the phosphor-bronze fiber brush can be suppressed by the lubricating effect of expanded graphite.The wear rates of the negative and positive brush without expanded graphite are 5.83×10-9 m/m and 1.12×10-8 m/m respectively.As the content of expanded graphite increases to 29.1%,the wear rate of the negative and positive brush decrease to 0.44×10-9 m/m and 0.53×10-9 m/m respectively.

关 键 词：纤维电刷 膨胀石墨 抗压强度 弹性系数 摩擦磨损 接触电压降 

分 类 号：TG142[一般工业技术—材料科学与工程]