Tribological behavior of glass fiber reinforced-PA66 in contact with carbon steel under high contact pressure, sliding and grease lubricated conditions

Polyamide 66 is widely used for sliding parts, such as resin worm gear. Glass fibers are usually added to increase its strength. In this study, the tribological behavior of glass fiber reinforced-polyamide 66 composite in contact with carbon steel under high contact pressure, sliding, and grease lubricated conditions is studied. Measurement of mechanical properties and SEM observations of composite sliding surfaces after different sliding cycle numbers indicate that sliding induces characteristic damage of the surface (peeled off fibers and scratching of polyamide) and a degradation in mechanical properties. These lead to an increase in friction and creep of the composite. The wear effect increases with the increase in sliding cycles, and the initial orientation of the fibers in the composite sliding surface has significant effects on the wear of the steel counterpart. The contribution of each phenomenon to the tribological behavior is discussed. The damage to the composite surface and the increase in contact temperature due to sliding have great effects on the tribological properties compared to the presence of wear debris in grease and wear on the steel. The effects of the hardness of the steel on the tribological properties are investigated, and it is found that wear of the composite is reduced by using softer steels.