Formation mechanism of electrical damage on sliding lubricated contacts for steel pair under DC electric field

A dynamic electrical pitting tester has been developed to investigate the effects of supply voltage, supply current, and oil film thickness on the electrical behavior, the normal and frictional forces, and the formation mechanism of electric damage for the sliding lubricated contacts of steel pair under DC electric field. Based on the experimental results for the normal and frictional forces, and the observations of the pitted surface, the process by which electrical damage occurs on the sliding lubricated surfaces is deduced. In this process, the molten metals are attracted to each other, leading to the formation of a molten metal column, which becomes a semisolid metal column due to the cooling action of the oil film. The normal force is significantly affected by this semisolid column, which grows and pushes against the lubricated contacts. Results also show that the frictional force primarily comes from the electrostriction force. The correlation formula for the damage width in terms of supply voltage, supply current, and oil film thickness is derived, but the supply current is the most important parameter affecting the width of the electric damage.