Behaviour of model abrasive particles between a sliding elastomer surface and a steel counterface

Abstract

Wear at a sliding elastomer–steel interface may occur as a result of direct interaction but also as a result of intervening particles. Much previous work to study abrasion of elastomers has involved the use of blade abrader arrangements. In the current work, a complementary approach is adopted; the short term and longer term motion of model particles (mild steel cylinders and hexagonal rods of steel and of quartz) has been modelled (by means of Finite Elements, FE) and studied experimentally. FE modelling supported by experiment has indicated that a cylindrical model particle rolls when between a sliding rubber block and a (dry) steel counterface. At low loads, the tangential velocity of the “particle” matches, while at high loads, exceeds the velocity of the rubber block. For hexagonal model particles of steel and also of quartz, the particle initially slid on the (oxidised) steel counterface — the ratio of horizontal to vertical force being low (≈0.10–0.14). However, continued sliding produced clean metal surfaces and hence a coefficient of friction sufficiently high (≈0.20–0.25) that incipient rolling of the particle occurred between rubber block and steel counterface. A similar pattern of behaviour was observed with a worn irregular particle of limestone. For a sharp-edged irregular particle of quartz, however, rocking rather than sliding occurred immediately. FE analysis was successful in modelling rolling of the hexagonal particle and in predicting the approximate (steel-particle) frictional coefficient required for rolling to just occur — although the experimental values were somewhat lower. The findings suggest that a number of patterns of particle movement (and thus modes of stressing of the rubber) may occur in rubber where it slides over mild steel in the presence of abrasive particles (and oxygen); what mode of stressing occurs will depend, inter alia, on what type of abrasion occurs at the particle–steel interface.