A study of break-in film development with different piston ring coatings and correlation with electrical contact resistance measurements

摘要

The film formation including hydrodynamic oil film and chemical boundary films was studied experimentally by using an electrical contact resistance method during the break-in period of coated piston rings rubbing against a cylinder bore segment. A simplified one-dimensional film model was developed to describe the film formation and correlated to the electrical contact resistance measurements. Two scaling factors were determined from the electrical resistance measurement during the break-in film development. The modeling results agreed well with the experimental measurements when the scale factors were selected appropriately in the model. Parameters such as applied normal load, surface roughness, lubricant viscosity, and Young's modulus of the ring coatings were considered in film modeling. The experimental results showed that the behavior of break-in film development was affected by the oil additives. The numerical simulation results showed that the film developed more quickly with decreasing normal load and lubricant viscosity and with increasing surface roughness and Young's modulus.