Assessment of the Wear of Composite Coatings in Reciprocating Line Contact Conditions

Aerospace dry-bearing materials commonly consist of a plastics-composite coating, typically 200 to 400 μm in thickness, adhesively bonded to a metal substrate. These materials are intended for use at high loads and low speeds, and assessments of their performance in full-scale bearing tests are expensive and time-consuming. This paper describes an accelerated test procedure for determining the wear behavior of such coatings, in which a small coated strip is loaded in nominal line contact against a rotating metal ring. The advantages and limitations of the method are discussed and examples given relating to (1) comparative screening of commercially available bearing liners, (2) effects of coating structure and composition on wear, (3) importance of the adhesive bond between the coating and its substrate, and (4) assessment of which particular parameters, amongst the many known to influence sliding behavior, are most important to the wear of these coatings. One problem identified by the work is the need for more information on the mechanical properties of thin composite coatings.