Sliding Friction of Copper
Abstract
The sliding friction between copper specimens were measured under atmospheric conditions under loads of 0.1 to 20 grams. With very clean surfaces* the coefficient of friction was 1.0-1.1 for the entire load range. With less clean surfaces, the coefficient of friction obtained was about 0.4. Since the degree of cleanliness cannot be controlled quantitatively, the friction - load curve of sliding copper pairs in air exhibits a bifurcation characteristic. The higher friction value may be satisfactorily explained by adhesion theory. No sign of adhesion, however, was detectable when the friction coefficient was 0.4. All observations to date indicate that plastic deformation: exists during the sliding process. Using published data on the total expended work in plastic deformation, the coefficient of friction between copper pairs was estimated to be about 0.2. When adhesion is negligible, based on the plastic deformation mechanism, one may deduce that (1) the friction coefficient depends largely on the properties of the softer material of the two specimens, and (2) upon repeated sliding, a slight drop in friction may be observed. Both of these predictions have been verified experimentally.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1963
- Accession Number
- ADA375187
Entities
People
- Tung Liu
Organizations
- Air Force Research Laboratory