SUMMARIES OF TWO LECTURES RECENTLY GIVEN AT THE POLYTECHNIC

“Friction of Metals” This lecture describes in simple terms the adhesion theory of metallic friction. On this view when two metal surfaces are placed in contact the surfaces are supported on their asperities and these flow plastically until the area is sufficient to support the applied load. As a result the area of true contact is directly proportional to the load and independent of the apparent area of the solids. Over the regions of contact strong adhesion occurs and the friction is primarily equal to the force required to shear the junctions so formed. This simple mechanism explains the two basic laws of friction due to Amontons—that the frictional force is proportional to the load and independent of the area of the sliding bodies.