Performance properties of lithium greases with PTFE particles as additive: Controlling parameter- size or shape?

Abstract The tribo-performance of Lithium-based synthetic greases based on poly-alpha olefin as a base-stock and Polytetrafluoroethylene particles (4 wt%) of different sizes viz. 50 nm, 6 μm, 9 μm and 12 μm and shapes as a functional additive were developed and tribo-investigated. Tribo-results revealed that the smaller the size, better was the performance in general. However, there was a strong competition between small particles 6 μm and nano-particles (50 nm) for best performance. The 6 μm particles showed slightly better performance, mainly because of their spherical shape. It was concluded that both the size and shape of particles were the controlling factors.