Friction and Wear Behavior of Self-lubricating Ceramic Composite

Al_2O_3/TiC self-lubricating ceramic material with addition of CaF_2 was produced by hot pressing.Friction and wear behaviors of the self-lubricating material were investigated on an MRH-3 ring-on-block friction and wear tester under dry friction,and worn surface morphologies were observed on a scanning electron microscope.It was found that the composite with 10% CaF_2 content showed higher bend strength,fracture toughness,and hardness compared with that of the composites with 5% and 15% CaF_2 content owing itsporosity absent and finer microstructure.Friction coefficient is reduced with increasing of CaF_2 content,speed and load individually.A lubricating layer was generated on the worn surfaces under high speed and load,which accounted for the friction-reducing and antiwearability of the self-lubricating material at high speed and load.While at low speed,abrasive wear is the main wear mode and the lubricating layer is difficultly generated.But solid lubricant existing between friction surfaces can still contribute to reducing the friction coefficient.Cracks were found on the surface of the self-lubricating film under repeated frictional condition because of mechanical stress and thermal stress.