Principais processos e meios de desgaste ……………………………………………. Tab. 2-3Classificação proposta por Chatterley; Macnaughtan (1999), das ligas dos discos de freio, de acordo com o teor de carbono………………….

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Purpose This paper aims to understand the effect of steadite in gray cast iron (GCI) cylinder liners performance (friction and wear) when lubricated with new lube oil formulations to verify if steadite can be reduced or suppressed from cylinder liners composition. Design/methodology/approach The paper presents an experimental approach to quantify the separated effect of lube additives and steadite content on GCI performance. Friction and wear of GCI samples with and without steadite were analyzed under lubricated conditions with a 5W30 lubricant and a base oil of similar viscosity under operating conditions similar to the ones observed at the top dead center of Otto engines. Scanning electron microscopy (SEM)-EDS analysis was used to evaluate wear and tribofilm formation. Findings The paper shows that steadite stabilizes friction coefficient and slightly reduces wear in the tests performed with base oil. However, its advantages are marginal in comparison to the ones provided by the fully formulated oil. Furthermore, SEM-EDS analyses of the wear track showed that steadite does not chemically react with zinc and sulfur compounds, reducing the tribofilm formation on the real area of contact and consequently changing the tribosystem behavior. Originality/value This paper covers an identified need to study the effect of lube additives and GCI composition using actual piston ring and cylinder liners under operating conditions similar to the ones observed at the top dead center of Otto engines.

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