Influence of chemical composition and microstructure of gray cast iron on wear of heavy duty diesel engines cylinder liners

摘要

This work aims to study the influence of the chemical composition and the microstructure of gray cast iron on wear of heavy duty diesel engines cylinder liners. Two kinds of lamellar gray cast iron are studied: a classical gray cast iron and a micro-alloyed gray cast iron. Polished sampleare tested. Reciprocating friction tests with the configuration steel ball against a flat sample, extracted from a cylinder liner, in lubricated contact are carried out on a Cameron Plint test rig (with commercial synthetic oil for diesel engines of the type 5W30). The friction coefficient and the electrical contact resistance are measured during all tests. The tribochemical film formation on the wear scars of the samples and the steel ball is studied after different friction periods. The wear volume evolution of the cylinder liner part and the steel ball are determined. The influence of the presence of hard phosphorous eutectics on the tribochemical film formation and on the wear behavior of cast iron is identified. After tribochemical film formation, the wear rate decreases considerably for all the samples. The micro-alloyed cast iron shows a better wear resistance than the "classical" cast iron. However, no tribofilm is formed on hard phosphorous eutectics and carbides.