On the two modes of operation of monolithic Ag-C brushes

Electrical Contacts, 1988., Proceedings of the Thirty Fourth Meeting of the IEEE Holm Conference on Electrical Contacts Pub Date : 1900-01-01 DOI:10.1109/33.31429

D. Kuhlmann-wilsdorf, D. Makel, N. Sondergaard, D. Maribo

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引用次数: 9

Abstract

The transition from low-temperature to high-temperature behavior in silver-graphite brushes may be explained either by changes of constriction resistance due to the temperature dependence of electrical resistivity and hardness at negligible film resistivity and one to three contact spots, or by loss of graphite lubrication within the interfacial film. These two interpretations were tested by controlling the contact spot temperature by (1) heating in an oven, and (2) local heat input through friction. Correlated studies of contact resistance, friction, wear rate, wear chip size, and wear chip microstructure, and calculations of contact spot temperatures, favor the second hypothesis. Micrographic evidence suggests that the loss of lubrication occurs through desorption of water vapor from the graphite. It is found that primary wear particles form because of the wedge mechanism and because of cutting by graphite fragments steeply inclined to the interface. Silver fragments may consolidate into secondary wear particles.<>

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单片Ag-C电刷的两种工作方式

银石墨刷从低温到高温行为的转变可以解释为电阻率和硬度在可忽略的膜电阻率和一到三个接触点的温度依赖性导致的收缩阻力的变化，或者是界面膜内石墨润滑的损失。这两种解释是通过(1)在烤箱中加热和(2)通过摩擦输入的局部热量来控制接触点温度来测试的。接触阻力、摩擦、磨损率、磨损芯片尺寸和磨损芯片微观结构的相关研究，以及接触点温度的计算，支持第二种假设。显微照片证据表明，润滑的损失是通过从石墨中解吸水蒸气而发生的。研究发现，初磨颗粒的形成是由于楔形机制和石墨碎片向界面倾斜的切削作用所致。银碎片可能固结成二次磨损颗粒。

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Electrical Contacts, 1988., Proceedings of the Thirty Fourth Meeting of the IEEE Holm Conference on Electrical Contacts

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