Three-body abrasive wear by (silica) sand of advanced polymeric coatings for tilting pad bearings

Aromatic Thermosetting Polyester (ATSP)-based coatings exhibit extremely low wear rates (4.15×10-8 mm3/Nm) under boundary lubrication simulating tilting pad bearings in harsh conditions. It is acknowledged that coatings' resistance to abrasive particles encountered in the bearing is also critical; the abrasive wear resistance of ATSP-based coatings and polyether ether ketone(PEEK)-based coatings are studied in this work using an accelerated wear experimental configuration with submerged lubrication and 2% weight of silica sand. The coatings' performance is compared with bare substrate (C182000 chromium copper) material. The results demonstrate that ATSP-based coatings have good abrasive wear resistance and very stable coefficient of friction (COF) because of their elastic deformation and a black tribo-layer that forms on the surface. ATSP-based coatings exhibit higher wear rate after adding the silica sand, while the wear rate of PEEK-based coating decreased with silica sand compared with no silica sand condition due to silica sand working as solid lubricant. The abrasive wear mechanism of ATSP was studied by varying the duration of experiments between 3420 m and 13,680 m, different silica sand size particles and different pin materials; scanning electron microscopy (SEM), micro-scratch testing and X-ray photoelectron spectroscopy (XPS) were used to verify the wear mechanisms.