Influence of steadite on the tribological behavior of cylinder liners

Abstract

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.

Effect of an Aftermarket Additive in Powertrain Wear and Fuel Consumption of Small-Capacity Motorcycles: A Lab and Field Study

“…This situation is similar to that observed at the beginning of tooth gearing, in which high levels of sliding occur [26]. Furthermore, boundary lubrication (Λ < 1), high contact pressure, and sliding motion across the texture direction are ideal conditions to test additives' performance [20,21,27], particularly anti-wear and extreme pressure additives, which are the main constituents of most aftermarket additive packages for engine oils [1,9]. Under these conditions, metal contact under higher stress occurs, leading to asperity deformation and wear, which in turn trigger the additives [23].…”

“…However, the chemical elements observed in each ring were different. While calcium, phosphorus, sulfur and zinc were detected in the piston rings from Motorcycle B, as observed by many scholars [21,27,46], the piston ring from Motorcycle A presented only calcium. The lack of the other chemical elements from the 10W-30 engine oil on the piston rings from Motorcycle A clearly indicates the metal conditioner formulation has a synergic effect with the engine oil and alters tribofilm formation and composition.…”

“…Worn surfaces of the compression, middle and oil control rings from both motorcycles presented similar wear mechanisms, which are typical of mild sliding wear with two and three-body abrasion, as observed by surface smoothening, vertical scratches and indentations [21,27,46]. Adhesion and corrosion, which are usually observed in piston rings, did not play a significant role.…”

Brazilian Tribology: origin, status quo and future perspectives

“…A particular area of current concern is the correlation between laboratory experimental results and field-testing data. The ITV Tribology Group currently comprises five full-time researchers and about 15 Master, PhD and Postdoc students, as well as several academic visitors, working on a wide range of problems, including materials for rails [252,260,286,287,[452][453][454][455][456] and railway components [252,287,455], materials for iron ore grinding and crushing [300,445,457], conveyor belt components, lubrication [43,452,[458][459][460], contact mechanics, friction, wear, tribo-corrosion, surface fatigue and emerging technologies like robotics, advanced materials and green ship. This summary of the main activities in each group gives an extensive overview of the Brazilian tribology in different contexts.…”