Study on the Preparation and Tribological Properties of Fly Ash as Lubricant Additive for Steel/Steel Pair

Fly ash, generated during the combustion of coal for energy production, has been regarded as an environmental pollutant if not properly disposed of. Many aggressive efforts have been evaluated to recycle the fly ash. In this paper, a new approach was developed to prepare lubricant additive based on fly ash and the tribological properties were investigated in detail. The results show that fly ash modified with oleic acid not only performs favorable dispersive ability, but also significantly improves the friction-reducing and anti-wear abilities for steel/steel contact. Based on the characterization of the wear scars by scanning electron microscopy, Raman spectroscopy and energy-dispersive X-ray spectroscopy, the excellent tribological properties are attributed to the synergies of fly ash and oleic acid because fly ash can act as spacer and bearing and deposit on the worn surfaces to significantly improve the friction-reducing and anti-wear abilities, and the introduction of strong polar groups can make fly ash easily form a stable and successive tribofilm on the rubbing surfaces throughout the sliding process.