Friction and wear behavior of flame-sprayed PEEK coatings

Polyetheretherketone (PEEK) becomes of great interest to applications as bearing and slider materials. In this paper, PEEK coatings with three kinds of crystallinities were deposited using the flame spray process. Employing a uniform design experiment, the friction and wear behavior of the three PEEK coatings were systematically investigated under dry sliding conditions against a 100C6 counterbody on a ball-on-disc arrangement for several loads and sliding velocities. For the three coatings, the friction coefficient significantly followed the normal distribution. The average friction coefficients appeared to decrease while increasing the sliding velocity, but were insensitive to the applied load in the range of investigation. Among the three coatings, the higher the crystallinity of the coating, the lower its average friction coefficient was. The wear rate of the coating with the lowest crystallinity decreased with an increase in the load and a decrease in the sliding velocity. The wear rate of the coating with the intermediate crystallinity decreased with an increase in the load, but increased with an increase in the sliding velocity at lower loads, and then decreased with an increase in the velocity at higher loads. The wear rate of the coating with the highest crystallinity decreased with the increase of both the load and the sliding velocity. The wear mechanisms of the different coatings are explained in terms of plastic deformation, plogh marks and fatigue tearing.