• Sakamoto, Kiyomi
• Shitara, Yuji
• Tatsumi, Go
• Mellor, Brian
• Ratoi, Monica

Abstract

Poly-Ether-Ether-Ketone (PEEK) has been widely used for tribological applications with steel counterparts because of its superior mechanical and self-lubricating properties. Lubrication has the potential to further improve its performance. However, lubrication can have positive or negative effects depending on the operating conditions and little is known about the mechanism of lubrication. To elucidate these aspects, the friction and wear properties of the PEEK/steel contact in both dry and poly-α-olefin (PAO) lubricated conditions were investigated by tribological tests and surface analytical techniques. The nanoindentation measurements showed that lubrication with PAO had a softening effect on the wear track of PEEK, but no correlation was established with the wear of PEEK. The tribological behavior, for both dry and lubricated contacts, was correlated with the formation of PEEK transfer films on the steel counterparts. The thickness of these films, as determined by Electron Probe Micro Analysis (EPMA) and X-ray Photoelectron Spectroscopy (XPS), was controlled by the rates of their transfer and removal and depended on the operating conditions. Moreover, lubrication with PAO not only inhibited the transfer but also suppressed the removal of PEEK films. This study thus sheds light on the mechanism of lubrication of the PEEK/steel contact.

Topics

• impedance spectroscopy
• surface
• x-ray photoelectron spectroscopy
• steel
• nanoindentation
• ketone
• electron probe micro analysis