The role of surface texture on friction and transfer layer formation

In the present investigation, various kinds of textures, namely, unidirectional, 8-ground, and random were attained on the die surfaces. Roughness of the textures was varied using different grits of emery papers or polishing powders. Then pins made of Al-4Mg alloys were slid against steel plates at various numbers of cycles, namely, 1, 3, 5, 10 and 20 using pin-on-plate reciprocating sliding tester. Tests were conducted at a sliding velocity of 2 mm/s in ambient conditions under both dry and lubricated conditions. A constant normal load of 35 N was applied in the tests. The morphologies of the worn surfaces of the pins and the formation of transfer layer on the counter surfaces were observed using a scanning electron microscope. Surface roughness parameters of the plates were measured using an optical profilometer. In the experiments, it was observed that the coefficient of friction and formation of the transfer layer depend on the die surface textures under both dry and lubricated conditions. More specifically, the coefficient of friction decreases for unidirectional and 8-ground surfaces while for random surfaces it increases with number of cycles. However, the coefficient of friction is highest for the sliding perpendicular to the unidirectional textures and least for the random textures under both dry and lubricated conditions. The difference in friction values between these two surfaces decreases with increasing number of cycles. The variation in the coefficient of friction under both dry and lubrication conditions is attributed to the change in texture of the surfaces during sliding. 1 2 3 4 The role of surface texture on friction and transfer layer formation 5 during repeated sliding of Al-4Mg against steel 6 7 8 Pradeep L. Menezes 1, 3† , Kishore 1 , Satish V. Kailas 2* and Michael R. Lovell 3 9 10 Department of Materials Engineering, Indian Institute of Science, Bangalore, Karnataka 560 012, India 11 Department of Mechanical Engineering, Indian Institute of Science, Bangalore, Karnataka 560 012, India 12 Department of Industrial Engineering, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA 13 14 15 Received Date Line (to be inserted by Production) (8 pt) 16 17 18 Abstract 19 20 In the present investigation, various kinds of textures, namely, unidirectional, 8-ground, and random were 21 attained on the die surfaces. Roughness of the textures was varied using different grits of emery papers or 22 polishing powders. Then pins made of Al-4Mg alloys were slid against steel plates at various numbers of cycles, 23 namely, 1, 3, 5, 10 and 20 using pin-on-plate reciprocating sliding tester. Tests were conducted at a sliding 24 velocity of 2 mm/s in ambient conditions under both dry and lubricated conditions. A constant normal load of 35 25 N was applied in the tests. The morphologies of the worn surfaces of the pins and the formation of transfer layer 26 on the counter surfaces were observed using a scanning electron microscope. Surface roughness parameters of the 27 plates were measured using an optical profilometer. In the experiments, it was observed that the coefficient of 28 friction and formation of the transfer layer depend on the die surface textures under both dry and lubricated 29 conditions. More specifically, the coefficient of friction decreases for unidirectional and 8-ground surfaces while 30 for random surfaces it increases with number of cycles. However, the coefficient of friction is highest for the 31 sliding perpendicular to the unidirectional textures and least for the random textures under both dry and lubricated 32 conditions. The difference in friction values between these two surfaces decreases with increasing number of 33 cycles. The variation in the coefficient of friction under both dry and lubrication conditions is attributed to the 34 change in texture of the surfaces during sliding. 35 36