Experimental Investigation of the Effect of Electrical Potential on Adhesive Friction of Elastomers

Abstract

Using an electrically conductive, carbon black filled rubber slider, it is found that the frictional force may be increased when an electrical potential is applied across the interface. Under certain conditions a two to three fold increase in friction was observed for voltages up to 2000 V. The current flow is generally so small that the power consumption does not exceed a few watts. Such a remarkable influence on friction obtained at the expense of only a small power may be of interest in certain applications. It is therefore interesting to study phenomenological laws of friction under these conditions. It is found that Amonton’s law of proportionality between normal load and frictional force is approximately valid for given speed, temperature and applied voltage.

Within the range of voltages used, the increase in friction was observed for rubber compounds with 50 p.p.hr carbon black content. No influence was observed for compounds which contained only 10 p.p.hr carbon black.

Some effort is made to understand the mechanism which is responsible for the observed increase in friction. It appears that the increase results from an additional electrical force which supplements the normal force on the real area of contact. An alternative explanation based upon rise in the intrinsic coefficient of friction is thought to be less plausible. In order to elucidate the details of the mechanism, certain experiments have been performed. An electrical model of the contacting bodies is considered.