Durability of chromium plating under dry sliding conditions

Experimental data are presented to show that engineering chromium plating on cast iron fails catastrophically after a given number of sliding cycles depending upon the applied load and the coating thickness. The failure mechanism involves the initiation of cracks in the chromium both at its sliding surface and at the coating-substrate interface adjacent to graphite flakes. The cracks propagate through the coating to give fracture and mechanical breakdown of the coating. The use of durability limit curves to identify ‘fail-safe’ conditions is discussed.