Tribological Properties of Alkyldiphenylethers in Boundary Lubrication

Renguo Lu,Shinji Koganezawa,Hiroshi Tani,Masaya Morimoto,Norio Tagawa

doi:10.3390/lubricants7120112

Abstract

Lubricants that are used in miniaturized moving mechanical components generally serve under severe conditions, such as high temperature, high speed, and high load. Although alkyldiphenylethers (ADEs) are used as base oils for high-temperature greases, their tribological properties remain unclear. This study investigated the influence of the alkyl chains on the tribological properties of ADEs. Longer and more attached alkyl chains decreased the friction coefficient of ADEs under both reciprocating and continuous sliding conditions. Wear was found to be independent of the alkyl chain under reciprocating sliding conditions due to abrasion being caused by debris that was not readily removed. ADEs showed good anti-wear properties when used as either a lubricant or an additive under continuous sliding conditions. Much smoother surfaces in the friction track were observed in comparison to poly-α-olefin. Fourier-Transform infrared spectroscopy analysis suggested that the ether groups were attracted to the worn steel surface, phenyl groups became consequently perpendicular, and the attached alkyl chains repelled other substances and prevented further wear of the surface. Moreover, ADEs showed a high adaptability with traditional additives.

Highlights

As machines have been increasingly downsized in recent years, demand for smaller, lighter, higher-speed, and maintenance-free moving mechanical components has grown [1,2,3]
When the alkyl chain length increased to C18, the friction coefficient decreased to 0.105
These results showed that the friction coefficients of ADEs strongly depended on the alkyl chain length

Summary

Introduction

As machines have been increasingly downsized in recent years, demand for smaller, lighter, higher-speed, and maintenance-free moving mechanical components has grown [1,2,3]. Lubricants used in such components generally serve under severe conditions, such as high temperature, high speed, and high load. It is known that temperature rise, thermal decomposition, and oxidative deterioration in lubricants occur due to the breakage of the oil film under operating conditions of high temperature and high speed. It is known that lubricant oils tribochemically decompose, due to the high activity of a nascent steel surface: hydrogen and gaseous hydrocarbons are generated [4].

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Results

Conclusion