Avaliação tribológica do sistema anel-camisa utilizando componentes novos e usados

Abstract

The present investigation aims to evaluate the tribological behavior of the ring-liner system varying the condition on use of the components, being these fresh and aged. For this evaluation cylinder liner samples, made of gray cast iron were tested. The worn sample of cylinder liner was collected from an engine that was tested in dynamometer for 500 hours and the SAE 15W 40 lubricant oil was obtained under different conditions: one oil is fresh and the other oil is aged after 400 hours of dynamometer test. As counter bodies, samples of rings made of martensitic stainless steel were used. Different combinations were used to evaluate the effect of aging of the liners and oils, being the Test 1: new liner with fresh oil, Test 2: new liner with used oil and finally, Test 3: used liner with aged oil. The tribological tests were carried out with a 4 h duration using a universal tribometer in a reciprocating setup, applying a load of 170 N and a constant oil temperature at 100 °C. The roughness of the liners was determined by optical interferometry. The variation of the roughness parameters of the K family was used as a method to evaluate the wear of the liners. Dispersive energy X-ray spectroscopy (EDS) was used to verify the possible formation of films on dynamometer-tested surfaces. Analysis of the lubrication regime showed that all the tests were performed within the boundary region. The test with new components showed a higher coefficient of friction when compared to the test with used ones. The test condition of new liner with aged oil was the one that showed the greater wear, e.g., the greater variation of the roughness parameters of the K family. Finally, a correlation analysis was performed between the wear results and the amount of zinc and phosphorus elements, which belonging to the ZDDP, which is used in lubricant oil for wear reduction. With this, it was possible to observe that the samples that presented higher values of (Zn + P) resulted in lower wear.