The Effect of Sliding Speed on the Wear Mechanisms of IS304 Self-lubricating Coating

Self-lubricating coatings prepared by Induction sintering had fine and uniform lubricating phases. Wherein the size of lubricating phase Ag and fluoride was about 5 μm,respectively,and the size of strengthening phase Cr₂O₃ was smaller than 1 μm. The worn surface was rough at low sliding speed,and the main wear mechanisms were abrasive wear and fatigue wear. However,the worn surface was smooth at high sliding speed. Although abrasive wear and fatigue wear were still the wear mechanisms of coatings, Ag lubricating film was found on the worn surface. The formation of such lubricating film was responsible for lower coefficient of friction. The presence of Ag lubricating film was due to the frictional heat. As the sliding speed increased,the transient temperature of local area was significantly increased by the frictional heat. Then,Ag particles with high thermal expansion coefficient overflowed from the NiCr matrix. And the overflowing Ag particles were plastically deformed under pressure and friction to form the Ag film. When the sliding speed was 1m/s,the transient temperature rise,using the overflow volume calculation method was as high as 296 ℃. The temperature was significantly higher than the temperature rise calculated from finite element model.