WEAR-LIFE DIAGRAM OF TIN-COATED STEELS

This paper will present the results of indentation, one pass scratch a nd the repeated sliding tests to determine the critical load and the w ear-life of TiN coated specimens. The sliding tests of cone(diamond)-o n-disc type were performed under dry sliding conditions as well as ind entation and scratch. The test specimens were 0.2% plain carbon steels . The coefficient of friction and the wear cycles to failures were mea sured with different coating thickness, substrate hardness and roughne ss. From the scratch tests it was confirmed that the critical loads in creased with the hardness of the substrate, furthermore the critical l oads are increased with the coating thickness and decreased with incre asing surface roughness. Using the percent contact load, the ratio of sliding normal load to the critical scratch load, the cycles to failur e are measured to predict the wear-life of TiN film. On the wear-life diagram, the percent contact loads and the cycles to failure show the good linear relation on log coordinate. With a decreasing load percent age, the diagram shows that the wear-limits, at which the coated steel s survive more than 4000 cycles, an about 6-10% of the critical scratc h loads. (C) 1998 Elsevier Science S.A. All rights reserved.