Wear behaviour of a spontaneously liquid infiltrated aluminum alloy matrix composite in pin-on-disk high velocity dry sliding wear tests

Spontaneous liquid infiltration of alumina preforms is a well known method for the production of disks to be used in brakes for motorcycles, automobiles and even rail transportation. The pin on disk wear testing is a mean to evaluate the suitability of the Alumina-Aluminum alloy composite for such applications and moreover allows to evaluate the stability of the surface of the rotating composite disk in contact with a stationary counterpart. A series of high velocity dry sliding wear tests were carried out on a properly modified horizontal lathe, against metallic and brake lining counterparts. Friction coefficients as well as the wear rates were determined during pin-on-disk and flat-on-disk tests carried out at different sliding speeds, up to 15 m/s. The sliding speed heavily affects the stability of the composite which showed increasing degradation rate with increasing speed. The microstructural examinations carried out by means of light and scanning electron microscopy showed the important role played by the third body, which enhances delamination, especially during the tests carried out at the highest sliding speed.