Some high power-density diesel engines employ unstable splash lubrication for connecting rod small ends, driven by structural strength considerations. However, the shrink-fitted bushing may loosen due to the high temperature generated by starved lubrication. This paper illuminates the friction characteristics of piston pin made of carbon/carbon (C/C) composite under starved lubrication. The coefficient of friction, bushing temperature, and surface morphology were analyzed. Three piston pins made of C/C composite were graphitized at different temperatures and then tested. The results indicate that C/C composite, predominantly consisting of smooth laminar pyrolytic carbon, exhibits lower temperature and coefficient of friction while maintaining surface stability. Then the friction characteristics of the C/C piston pin were compared to those of a steel piston pin. It is found that C/C piston pin has a lower coefficient of friction and superior anti-seizure capacity at high swing frequencies. This not only effectively reduces bushing temperature but also prevents the significant friction forces generated by severe adhesion, which helps suppress bushing looseness. These results offer valuable insights for the design of friction pairs under starved lubrication.
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