Tribological and strength properties of alumina/multi-walled carbon nanotube composites

The Al2O3/MWCNT composites with MWCNT content up to 10 mass% have been prepared by spark plasma sintering. The effect of MWCNT addition on the tribological and strength properties was investigated, The experimental results revealed that the steady-state friction coefficient (mu) of the composites decreased with increasing up to 4 mass% MWCNT and stayed constant (mu=0.33) with further addition of MWCNT, which value was substantially lower than that of MWCNT-free monolithic Al2O3 (g=0.57). These properties seem to be related to the formation of MWCNT-derived transferred film made up of carbonaceous material during sliding. However, it has not been demonstrated that the presence of MWCNTs improves the fracture strength and fracture toughness of the composites. It is mainly due to the agglomeration of M`WCNTs and the weak interface between MWCNTs and the Al2O3 matrix.