The Mechanism of Tribological Wear of Thermoplastic Materials

Sliding machine elements made of plastics co-operate mostly with metals. The friction of these materials engages several processes like mechanical and adhesion interactions, tribo-chemical and tribo-electrical reactions etc. In this paper, processes involved with the tribological wear of polymer materials under conditions of dry friction were discussed. The focus was on mechanical and adhesion reactions between co-operating surfaces. The role of the surface roughness of the metallic element on the creation of the polymer film and on the wear of the polymer material was stressed. Fundamental modes of wear characteristic for polymer materials were described. These include adhesion wear, abrasive wear, fatigue wear, thermal and chemical wear, asperities melting, creep wear, and fretting. A wear mechanism for different polymer materials (including composites) was presented. The mechanism includes chemical activity of the mating metals, the role of fillers in the transfer of load and creation of the polymer film. A mechanism accounting for additional heating of the material as a result of fluctuating friction force loading of the sliding metal/polymer pair and additional heating due to internal friction of the polymer materials was also presented.