2019 年 14 巻 2 号 p. 94-101
To clarify the wear mechanism of current collecting materials such as a contact wire and a contact strip under electric current condition, it is necessary to clarify temperature distribution around the contact spot. However, the traditional method of estimating the maximum contact temperature such as the φ-θ theory cannot estimate the temperature distribution. In this paper, we newly proposed an electric field analysis model of hard-drawn copper and iron-based sintered alloy considering a degenerated layer such as an oxide film and wear debris. Then, we newly proposed the heat conduction equation applying the Wiedemann-Franz law, and analyzed temperature distribution in electrodes. As a result, we find that the relation between the maximum temperature and the contact voltage even in dissimilar electrodes are based on the φ-θ theory. The temperature distribution in electrode changes depending on whether or not degenerated layers exist, and the maximum temperatures of each electrode are not necessarily the same as those estimated by the φ-θ theory. Finally, we clarify the influence of the degenerated layer on the melting condition of electrodes, and explain the electric wear phenomena observed in the previous wear test.
