Reciprocating frictional properties of C/C composite under different frequencies

The influence of reciprocating frequency on the sliding friction behavior of two kinds of C/C composites against GCr steel ball was investigated on a UMT-3 tester at 40 N.The results show that the coefficient of friction(COF) of the two C/C composites increases firstly with increasing the sliding frequency until it reaches the maximum at 400 r/min,and then the COF shows a similar linear decline except some fluctuation generated under 1 200 r/min.The COF of the composites with rough lamination pyrocarbon/resin carbon matrix(RL/RC) is larger than that of the composites with smooth lamination pyrocarbon(SL) matrix at the same sliding frequency.The COFs of the RL/RC-composites are in the range of 0.183-0.063,while those of the SL-composites are 0.150-0.059.The COFs of all the samples become more and more stable with increasing time.The results of Raman spectrum detection show that the graphitization of micro-worn-area composites with SL increases with increasing the reciprocating frequency.SEM images show that the worn surfaces of the two C/C composites change from smooth surface to rough surface with more plough-worn grooves.