Insights on the Formation Mechanism of Ultra-Low Friction of Phenolic Resin Graphite at High Temperature

Fan Zhang,Jianmei Wang,Peng Yin,Qunfeng Zeng

doi:10.3390/coatings12010006

Fan Zhang, Jianmei Wang + Show 2 more

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https://doi.org/10.3390/coatings12010006

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Abstract

In the present paper, the influences of high temperature on the tribological properties of phenolic resin graphite (PRG) sliding against tungsten carbide-nickel (WC-Ni) alloy in ambient air were investigated systematically. Results demonstrated that the antifriction behaviors of PRG was sensitive to high temperature and PRG exhibits ultra-low coefficient of friction (CoF) of about 0.01–0.015. The low CoF is attributed to the formation of graphite tribofilms, which shows different formation processes on the contact interface at different temperatures (room temperature, 200, 300 and 400 °C). These findings provide insight into the formation mechanism of graphite tribofilms, and provide an important basis for improving the tribological properties of graphite-based friction materials and manufacturing new graphite for seal applications.

Highlights

Performance of the mechanical seal in an aerospace engine is mainly determined by the tribological properties of friction pairs which are mostly composed of graphite and cemented carbides [1,2]
Jia et al [13] experimentally studied the tribological properties of impregnated graphite under a dry and corrosive environment, and the results showed that the degree of graphitization had an important influence on the friction coefficient
(2) At room temperature, the graphite material is mainly subjected to extrusion and shear force and crushed to form cracks, forming point, sheet and strip fragments with uneven size and shape

Summary

Introduction

Performance of the mechanical seal in an aerospace engine is mainly determined by the tribological properties of friction pairs which are mostly composed of graphite and cemented carbides [1,2]. During the use of the mechanical seal, due to excessive frictional temperature rise, the surface of the metal moving ring is deformed at high temperature and blue due to overheating. It is necessary to study the friction and wear performance of the pair at high temperature. Compared with traditional basic lubricants such as molybdenum disulphide (MoS2) [3] and polytetrafluoroethylene (PTFE) [4], graphite has been recognized as the ideal seal material and is commonly used as a soft face in the friction pair of the seal due to its self-lubricating performance, high thermal conductivity, excellent chemical stability and corrosion resistance [5]. The hard face is often composed of tungsten carbide (WC)-based cemented carbides because of their mechanical strength, high abrasion and corrosion resistance [6,7]

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