Review: The anti-friction and anti-wear mechanism of lubricate oil additives in the piston ring-cylinder liner system of engines

Purpose To effectively meet the special requirements under various operation conditions of marine engines, lubricant base oils are often formulated with suitable additives to enhance the comprehensive performance. An in-depth understanding of the additives’ mechanism is of great significance in exploring the abnormal wear in marine engines and other related issues. Design/methodology/approach First, the absorption mechanism of anti-friction additives was described in an overview, and the formation process of the boundary film and its influencing factors are discussed under the perspective of mathematical modeling. Subsequently, the typical types of anti-wear additives and their tribochemical reactions are emphasized, and zinc dialkyl dithiophosphate (ZDDP) was selected as an object of investigation, and the thermal and mechanical stress activation conditions on the tribochemical reaction process were discussed through the tribofilm growth and wear models. Finally, the research process of tribochemical reactions in the piston ring-cylinder liner (PRCL) system in marine engines is discussed from both experimental studies and numerical simulations, and the current challenges to be solved by applying to tribochemical reactions mechanism to PRCL are analyzed. Findings This paper reviews the main components, mechanism of action and basic characteristics of anti-friction and anti-wear additives, and summarizes the formation process of the boundary film, tribofilm and their influencing factors. At the same time, the typical types of anti-wear additives and their tribochemical reactions are emphasized, especially for the ZDDP, and the influence of thermal and mechanical stress activation conditions on the tribochemical reaction process is discussed. Finally, this paper discusses the research process of tribochemical chemical reaction in the PRCL system of the internal combustion engine, and analyzes the current challenges of applying tribochemical reaction mechanism to solve the engineering challenges of PRCL system. Originality/value The understanding of this study could be readily applied to the tribofilm growth and lubrication evaluation in engines. Furthermore, the proposed views and research ideas in this paper could be used in the engine industry. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2024-0496/