THE EFFECT OF SURFACE ROUGHNESS AND MATERIAL HARDNESS ON THE TRIBOLOGICAL PERFORMANCE OF THE SLIDING PAIR WC-42CrMo4 UNDER STARVED LUBRICATION

摘要

Ceramic materials are more and more popular in industrial applications. Machine elements made of ceramic materials are characterized by long durability, especially those elements that work in hard operating conditions. In this paper, the results of tribological examinations of WC-42CrMo4 sliding pair are presented. Tribological tests were realized with the T-11 stand with the ball-on-disc sliding pair. For lubrication, the machine mineral oil L-AN 46 was used. The analysis showed that surface roughness significantly affected the tribological performance of tested sliding pairs. Steel samples were characterized with various hardnesses in the range of 22-42 HRC and this feature also effected on friction coefficient. Statistical analyses of the achieved results were made using the 3-level PS/DC 3~2 design. According to the statistical analysis, the quadratic functions describing the dependence for friction coefficient on surface roughness and material hardness were obtained. The most unfavourable surface roughness was after the grinding process, but the best was those after the lapping process which allows the smallest friction coefficient.