Comparison Between Synthetic Oil Lubricants for Reducing Fretting Degradation in Lightly Loaded Gold-Plated Contacts

This article presents a comparison between the performances of two chemistries of synthetic oil lubricants, polyalphaolefins (PAOs), and perfluoropolyethers (PFPEs) when applied on gold-plated electrical contacts operating at contact loads of 9.8 centiNewton (cN) and experiencing fretting-induced degradation. Performance assessment was done using the contact resistance and coefficient of friction behavior and the surface’s response to fretting in the presence of three different lubricants, each within the two chemistries. It was found that the PAOs improved the fretting performance of the lightly loaded contacts and, statistically, were at least 50 times more reliable for a longer duration of fretting cycles than the PFPEs, suggesting their suitability for low contact load applications. At low loads, PFPEs underwent contact separation due to hydrodynamic lubrication, and the behavior was more observable among the PFPEs with higher kinematic viscosities. On the contrary, viscous PAOs had improved fretting performance and delayed time to contact failure than less viscous PAOs. The applied lubricant film thickness also contributed to the contact’s performance, and it was found that increasing the thickness of the PFPE films advanced contact failures, while thicker PAO films postponed the contact’s time to failure.