HARDNESS AND WEAR PROPERTIES OF BORON-IMPLANTED POLY(ETHERETHERKETONE) AND POLY-ETHER-IMIDE

The effects of boron beam irradiation on the hardness, friction, and wear of polymer surfaces were investigated. Typical high-performance thermoplastics, poly(ether-ether-ketone) (PEEK) and a poly-ether-imide (Ultem) were studied after 200 keV boron ion beam treatment at ambient temperature to doses of 2.3 x 10(14), 6.8 x 10(14), and 2.2 x 10(15) ions cm-2. The hardnesses of pristine and boron-implanted materials were characterized by a conventional Knoop method and a load depth sensing nanoindentation technique. Both measurements showed a significant increase in hardness with increasing dose. The increase in hardness was also found to depend on the penetration depth of the diamond indenter. Wear and friction properties were characterized by a reciprocating sliding friction tester with an SAE 52100 high-carbon, chrome steel ball at 0.5 and 1 N normal loads. Wear and frictional properties varied in a complex fashion with polymer type and dose, but not much with normal load. A substantial reduction in friction coefficient was observed for PEEK at the highest dose but no reduction was observed for Ultem. The wear damage was substantially reduced at the highest dose for both Ultem and PEEK. For the system studied, the highest dose, 2.2 x 10(15) ions cm-2, appears to be optimum in improving wear resistance for both PEEK and Ultem.