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The paper aims to investigate the friction and wear properties of three surface-modified piston rings matched with a chromium-plated cylinder liner.

Samples were taken from the chromium-plated cylinder liner, Cr-Al2O3 ring, CrN ring and Mo ring. Tribo-tests were conducted on a reciprocating sliding tribometer under fully formulated engine oils. Friction coefficients and wear depths of three friction pairs were tested. Surface morphologies of cylinder liners and piston rings before and after test were analyzed.

Experimental results show that in the Cr-Al2O3 piston ring, scuffing occurred easily when matched with the chromium-plated cylinder liner; compared with the Mo ring, the CrN ring could decrease the wear depth of the piston ring from 2.7 to 0.2 μm, and the wear depth of cylinder liner remained; however, the friction coefficient increased from 0.113 to 0.123. The tribological performances of three surface-modified piston rings were significantly different when they matched with chromium-plated cylinder liner.

Chromium-plated cylinder liner and the three kinds of surface-modified piston rings have excellent friction and wear properties, respectively. However, according to the systematic characteristics of internal combustion (IC) engine tribology, only the appropriate cylinder liner–piston ring can improve the tribological performance of the IC engine. This paper reports the tribological performance of three surface-modified piston rings matched with a chromium-plated cylinder liner. The results can be used as reference for the design of high-power-density diesel engine.

This paper aims to address the polymerization of 1-decene by [Emim]Cl/AlCl₃ ionic liquid and the film-forming properties of the product compared with commercially available base stocks.

Experiments were carried out to investigate the influence of [Emim]Cl/AlCl₃ mole ratio, catalyst dosage, reaction temperature, reaction time and water on the polyreaction. Poly alpha-olefin (PAO) is prepared under optimal reaction condition. Film-forming properties of PAO have been compared with those of Group I, Group II and Group III base stocks, which are selected with approximately the same viscosity.

Experimental results show that after a 4-h reaction time, yield of PAO can be higher than 85 per cent and viscosity index can be up to 160 with [Emim] Cl/AlCl₃ mole ratio of 2:1, catalyst dosage of 3 per cent wt. and water content of 20 ppm. A strong influence of water on reaction is observed. With approximately the same viscosity, PAO shows the superiority in film thickness at low-sliding speeds compared with Group I and Group II base stocks. At high temperature, PAO provides a thicker film than other base stocks.

In recent years, there has been considerable interest in ionic liquids. As a novel catalyst, it has so many advantages including low corrosion, low toxicity, low cost and a potentially wide range of properties compared with traditional catalysts. This paper reports the polymerization of 1-decene by [Emim]Cl/AlCl₃ ionic liquid and the study on lubricating properties of PAO compared with mineral base stocks.

The purpose of this paper is to establish a rapid and effective numerical model of thin film lubrication with clear physical conception, in which viscosity variation along the direction of film thickness was used instead of average viscosity, and continuous Reynolds equation was used in the calculation of thin film lubrication.

Based on rheology and thin film lubrication with point contact and considering features of shear thinning and like-solidification of lubricant oil in the thin film lubrication state, a modified formula with overall average equivalent viscosity was proposed by combining numerical calculation and experiment data.

It is a fast and efficient method for film lubrication state simulation.

Thin film lubrication research on a nanoscale is very popular, and a variety of thin film lubrication models are proposed. Due to the complexity of thin film lubrication, it is still in the stage of revealing law and establishing calculation model.

The key issue is how to obtain the viscosity correction formula derived from engineering practice, also considered the lubricating oil class solidification and shear-thinning properties on thin film lubrication, while based on the system experiment, the viscosity modified formula for the gap, speed changes are proposed to obtain the overall average equivalent viscosity which makes the thin film lubrication micro to macro, so that a clear physical meaning for thin-film lubrication numerical calculation model is established.