Comparative potential assessment of solid lubricants on the performance of poly aryl ether ketone (PAEK) composites

- Combination of solid lubricants (SL) led to synergism, which is rarely observed.
- Potassium titanate (KT) powder proved as efficient SL in bearing materials first time.
- Developed tribo-composites showed very high performance including PVlimts.

Poly aryl ether ketone (PAEK) is known as a high performance polymer superior to PEEK (poly ether ether ketone) in many aspects such as temperature stability, tribo-performance etc. Recently few efforts are put to enhance the tribo-potential of PAEK by developing composites containing short fibers of carbon and glass and most favored lubricants such as graphite, PTFE (poly tetrafluoroethylene), hexa boron nitride (hBN) etc. The wear and friction got significantly reduced to the extent that the composites showed very high potential as bearing materials for harsh operating conditions.Mica and boric acid (BA) are known as very good solid lubricants (SLs) with layer lattice structures. Potassium titanate (KT) powder also has been very popular ingredient of friction materials responsible for increasing wear resistance (WR) and reducing friction fluctuations. It is, however, never explored in bearing materials for enhancing tribo-potential.Keeping this in view, a series of composites was prepared by injection molding with identical parent composition but differing in type of solid lubricants (hBN, KT, BA and Mica). The tribo-performance was evaluated in adhesive wear mode on tribometer under severe operating conditions (700-900 N, velocity 1.63-3.5 m/s). Composites exhibited very low specific wear rates (K0) (2-8×10-16 m3/Nm) and very low coefficient of friction (µ) (0.04-0.08), which decreased with load and velocity. KT proved to be the most performing filler, while Mica was least effective followed by BA. Worn surface analysis by SEM (Scanning electron microscopy) and EDAX (energy dispersive x-ray) helped to understand wear mechanisms.