Effect of Externally Applied Electric Field on Friction and Wear Characteristics

The effect of an electric field applied between rubbing surfaces onfriction and wear characteristics was examined using a ball-on-disc testing apparatus under a mixed lubrication condition. The ball and disc were made of bearing steel with high hardness and plain carbon steel annealed with low hardness, respectively. The frictional characteristics were improved in an electric field where the disc was the anode, but with application of an electric field in which the disc was the cathode, the frictional characteristics were deteriorated. Improvement resulted from the formation of a passive-state film on the disc surface of the anode. The lowest limiting values of voltage and electric current possibleto form a passive-state surface film were found. Applying an electric field below the limiting values did not result in an effective passive-state film. The limiting values were also influenced by oxygen content in the oils tested.