不同电流下钯触头材料熔桥行为研究

用自制的电接触-高速摄像试验系统观测了钯触头材料在直流单分断模式下的电接触过程中的熔桥行为,用SEM分析触头表面形貌。结果表明,熔桥演化过程可分为熔桥形成、熔桥拉长和熔桥断开3个阶段,历时约2.08 ms;熔桥的形状有哑铃型和圆柱型2种,其尺寸为微米级,并且熔桥断开时具有针尖状的特征;熔桥行为会侵蚀触头表面形成具有熔池和凸丘等特征的表面特征;熔桥的直径和长度随电流的增大均呈现出先增大后减小的趋势,在熔桥形成之前可能有电弧出现,在DC 6 V的分断电压下,钯触头材料的理想工作电流不宜大于14 A。

Observation on Molten Bridge of Pd Electrical Contact Material under Different Current

The molten bridge evolution behavior of Pd electrical contact material was investigated by the homemade electrical contact-high speed video camera system under the DC and break only operation mode, along with the measurements of SEM morphology on the contact surface. Results showed that the evolution of Pd molten bridge could be divided into three stages: the formation of the molten bridge, the extension of the molten bridge and the rupture of the molten bridge during the process of electrical contact. The duration of these three stages was about 2.08 ms. The shape of the molten bridge had two types, dumbbell and cylindrical, and the dimension of the molten bridge was in micron level. The molten bridge would develop a needle tip-shape feature when it was broken. The molten bridge would erode the Pd contact surface, leading to the formation of molten pool and convex. Both the diameter and length of the molten bridge would build up with the increase of current and then diminished with the continuous increase of current. Arc phenomenon would occur before the formation of the molten bridge. The ideal working current of Pd contact material should not exceed 14 A under a DC of 6 V.