Effect of grain size on friction and wear behavior of Ti3SiC2

The effects of grain size on the sliding friction, sliding wear, and two-bo dy abrasive wear behavior of Ti3SiC2 were investigated. Samples with two di fferent grain sizes, namely, 5 mu m ('fine') and 100 mu m ('coarse'), were used as discs in pin-on-disc sliding wear tests against a 340C steel pin an d as rectangular pins in diamond belt abrasion tests. In the pin-on-disc te st, irrespective of the grain size, it was found that the material undergoe s an initial transition stage where the friction coefficient, mu, increases linearly to 0.15 to 0.45. After this transition stage, mu rises to steady state values, of about 0.83 for both coarse- and the fine-grained materials . It was concluded that the transition from the low to high mu is due to ac cumulation of debris entrapped between the disc and the pin, resulting in t hird-body abrasion. The average sliding wear rates in the pin-on-disc tests were 4.25 x 10(-3) and 1.34 x 10(-3) mm(3)/N m for the fine and the coarse grains, respectively. In the diamond belt abrasion tests. the average wear rates were much higher: 6.14 x 10(-2) and 3.96 x 10(-2) mm(3)/N m for the fine and the coarse grains, respectively. In the fine-grained material, it was concluded that the wear mechanisms include grain pre-fracture and remov al. Delamination, crack bridging, grain deformation, microcracking, and gra in fracture are the operative wear mechanisms observed in the case of the c oarse-grained material. It is this multitude of possible sliding energy dis sipation mechanisms that is believed to enhance the wear resistance of the coarse-grained material relative to the fine-grained one. (C) 2000 Elsevier Science S.A. All rights reserved.