Experimental study of the conducting spots in aluminum contact interfaces

Experimental results from a study of contact spots in aluminum-aluminum interfaces that have passed heavy direct currents are reported. The size, shape and appearance of the spot fractures were found to be correlated to the surface roughness and to the recorded voltage and resistance characteristics. Rough contact surfaces caused irregularly shaped contact spots to develop, while high and unstable resistances were always associated with large contact spots. The latter observation indicates that the electrical conductivity of the contact spots has been reduced by the electrical stresses.<
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