Tribological solutions for engine piston ring surfaces: an overview on the materials and manufacturing

ABSTRACT

This paper exhibits an outline of the piston rings operational characteristics and consequently, of their main functional challenges. The basic geometrical shapes, materials and manufacturing technologies used to produce compression rings for up to date diesel engines are summarized. Based on this description, each technological solution to enhance the behavior of the piston rings is fully described and explained. The state-of-the-art solutions such as a DLC (diamond-like carbon) layer, multi-layered coatings and compound coatings are tersely presented and discussed. New approaches suggest surface textures, which are expected to be a major improvement in the development of optimized surface coatings of the piston rings, and the latest progress in that area is examined and debated. Also, a novel solution for the enhancement of the behavior of ring coatings is presented, using a proposed and previously tested solution for a different application. This solution attempts to optimize most of the properties in relation to friction, wear, mechanical stresses, heat dissipation and self-lubrication. The overall idea is to use specific materials in specified positions over the surface to individually enhance the referred properties, creating a multifunctional surface.

Graphical Abstract

KEYWORDS:

• Engine
• piston ring
• tribology
• wear
• friction
• coatings
• multilayer
• surface
• textures
• cavities
• powder
• reinforcement

Highlights

• Full characterization of the compression piston ring-cylinder liner pair.

• Contextualization on the conventional solutions for the piston ring surface.

• Proposal of new technological approaches to improve piston ring performance.

• A review from the current solutions to proposals beyond the state-of-the-art.

Declaration of interest statement

The authors have no conflicts of interest to declare.

Data availability

A part of the data necessary to replicate these conclusions cannot become public at this time as the information constitutes a significant part of an ongoing project. The available data that support part of the findings of this study are available at https://doi.org/10.1016/j.triboint.2019.105843.

Additional information

Funding

This work was supported by FCT (Fundação para a Ciência e a Tecnologia) and MAHLE, Componentes de Motores, S.A under Grant [SFRH/BDE/110654/2015]; and FCT (Fundação para a Ciência e a Tecnologia) under Grant [SFRH/BSAB/142994/2018], and by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the project with reference NORTE-01- 0145-FEDER-000018-HAMaBICo, with the reference project UID/EEA/04436/2019 and by the project POCI-01-0145-FEDER-006941.