A special bearing tester was constructed to investigate the damage behavior on the lubricated surfaces in bearings with the passage of weak electrical currents as low as^1 mA.The results showed that when polar glycerine was used as the lubricant,many narrow and deep pits formed on the lubricated surfaces.In contrast,when the experimental conditions under the lubrication of the nonpolar paraffin oil were close to those under the lubrication of polar glycerine oil,damages on the lubricated surfaces were unobvious.Emergence of microbubbles in polar lubricants with the passage of electrical currents was proposed to be responsible for the observed damages on the lubricated surfaces.
