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 boundaryrnfilms was studied experimentally by using an electrical contact resistance method duringrnthe break-in period of coated piston rings rubbing against a cylinder bore segment. Arnsimplified one-dimensional film model was developed to describe the film formation andrncorrelated to the electrical contact resistance measurements. Two scaling factors wererndetermined from the electrical resistance measurement during the break-in filmrndevelopment. The modeling results agreed well with the experimental measurementsrnwhen the scale factors were selected appropriately in the model. Parameters such asrnapplied normal load, surface roughness, lubricant viscosity, and Young’s modulus of thernring coatings were considered in film modeling. The experimental results showed that thernbehavior of break-in film development was affected by the oil additives. The numericalrnsimulation results showed that the film developed more quickly with decreasing normalrnload and lubricant viscosity and with increasing surface roughness and Young’s modulus.