A Study on Wear Limit (pV-limit) of Ultra High Molecular Weight Polyethylene

Abstract

To decide pV-limit applicable to a wide range of experimental conditions, the friction and wear tests are carried out by using ultra high molecular weight polyethylene (UHMWPE), CFRUHMWPE and γ ray irradiated ones as samples. Two distinguishable phenomena in friction and wear have been observed. One is a usual phenomenon; the frictional force and the temperature of friction surface increase as the load increases. The wear rate is kept low in this state. The other is such that the frictional force and the surface temperature remain constant, even though the load is increased beyond a certain value. In this state, the wear rate increases abruptly with increasing load. The latter phenomenon is discussed in detail and the mechanism of this behavior is proposed on the condition that such behavior appears when the friction force reaches the shearing strength of the material and an apparent area of contact becomes equal to the real contact area. It may be concluded that, pV-limit is regarded as the state where the friction force saturates and remains constant, even though the load is increased (the saturated frictional force state).