AbstractThe present work aims to develop the abrasion resistance of surfaces lubricated by contaminated greases. The intended development can be achieved by reducing the effect of abrasive action of sand particles on the wear of the friction surfaces. Different polymeric thickeners in powder form, such as high density polyethylene (HDPE), low density polyethylene (LDPE), polyvinylchloride (PVC), polystyrene (PS), polyamide (PA6) and polymethylmethacrylate (PMMA), were added to lithium based grease. Friction coefficient and wear resistance of cylindrical steel specimens were examined using a cross pin wear tester. The wear tester provided concentrated contact under mixed lubrication conditions. Wear was measured on the stationary test specimen by the wear scar diameter, using an optical microscope, with an accuracy of ±1 µm. The frictional torque generated between the rubbing surfaces was measured using a load cell attached to the stationary test specimen holder. The experiments were performed using clean and sand contaminated lubricating greases. Air Cleaner Fine Test Dust (ACFTD Arizona Sand) was added as a contaminant to the grease at a concentration of 10 wt.%. The results show that the effect of the abrasive contaminants can be reduced by dispersing the grease by polymeric powders. However, the addition of polymer to lubricating grease at relatively high concentration (more than 35 wt. %) has no effect on the antiwear action of the lithium grease. Besides, the addition of polymeric powder of particle size relatively greater than that of the contaminant can be considered as a useful method of eliminating the cutting process of sand particles.
Ali et al. (Fri,) studied this question.