Purpose-This paper aims to investigate the wear behaviour of different materials for cylinder liners and piston rings in a linear reciprocating tribometer with special focus on the wear of the cylinder liner in the boundary lubrication regime. Design/methodology/approach-Conventional nitrided steel, as well as diamond-like carbon and chromium nitride-coated piston rings, were tested against cast iron, AlSi and Fe-coated AlSi cylinder liners. The experiments were carried out with samples produced from original engine parts to have the original surface topography available. Radioactive tracer isotopes were used to measure cylinder liner wear continuously, enabling separation of running-in and steady-state wear. Findings-A ranking of the material pairings with respect to wear behaviour of the cylinder liner was found. Post-test inspection of the cylinder samples by scanning electron microscopy (SEM) revealed differences in the wear mechanisms for the different material combinations. The results show that the running-in and steady-state wear of the liners can be reduced by choosing the appropriate material for the piston ring. Originality/value-The use of original engine parts in a closely controlled tribometer environment under realistic loading conditions, in conjunction with continuous and highly sensitive wear measurement methods and a detailed SEM analysis of the wear mechanisms, forms an intermediate step between engine testing and laboratory environment testing.

To decrease mechanical losses in internal combustion engines (ICE) a deeper understanding of the friction and wear processes in the main tribosystems is necessary. In particular, the interrelation between frictional energy and wear has to be analyzed. For this reason the hard to measure quantity of coefficient of accumulation of frictional energy, which is a pivotal parameter in some energy based wear theories, is determined in this work using model tribometer experiments. The experiments are performed using small specimens made of aluminium silicon alloy and gray cast iron with a SRV tribometer (linear reciprocating motion) where loading and lubrication conditions which closely simulate the real contact situation of a piston skirt sliding against a cylinder liner near the top dead center are applied. To calculate the coefficient of accumulation of frictional energy, experimentally gained values for the linear integral intensity of wear are analyzed numerically for various loading parameters (normal load, sliding speed, conditions of lubrication) which result in variation of the coefficient of friction and in the amount of wear. Finally the results of the correlation between the coefficient of accumulated energy in the piston skirt-cylinder liner tribosystem and the loading conditions

To describe and predict wear in a tribosystem, theoretical wear formulas and empirical models exist. Most of the existing formulations have a short range of validity and can only be applied for a specific contact situation. In this paper, the aim is to investigate a specific technical application of a tribocontact in an internal combustion engine. In particular, the contact between a piston skirt and a cylinder liner is experimentally simulated using a linear reciprocating tribometer and original engine parts, under closeto-reality loading conditions. The experimental findings will be analysed with a wear model that is most applicable to the actual tribosystem. This wear model, which is based on a combination of energy theories and a molecular mechanics approach, will be extended in the paper in order to add surface topography relevant parameters. The modified wear model is capable of combining the prediction of wear volume loss with the theory of fatigue and can be applied to any kind of tribosystems suffering damage due to reciprocating relative motion. For comparison with classical wear models, an empirical power law-including Archard as a special case-is shown. Using the measurement results of the tribometer, the parameters that are specific to the aforementioned wear model are determined. Furthermore, the applicability of the used model to describe the wear processes in this specific tribosystem will be discussed.

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