Effect of Borated Nanometer Calcium Carbonate Colloidal Nucleus on the Tribology Performance of Overbased Calcium Sulfonate Detergent

Borated overbased calcium sulfonate detergent was obtained in a way which nanometer calcium carbonate colloidal nucleuses were replaced by calcium borate and the colloid composite in comparison with overbased calcium sulfonate detergent were characterized by Fourier transform infrared analysis. Thermal stability tests in comparison were also conducted with a thermo-gravimetric analyzer. The tribology performance of overbased calcium sulfonate detergent and borated overbased calcium sulfonate detergent as additives in lithium complex grease were evaluated on an optimol SRV oscillating reciprocating friction tester and a fourball tester in details. The surface topography and chemical composition of wore surface after friction tests were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The results demonstrate that both overbased calcium sulfonate and borated overbased calcium sulfonate detergent improved the extreme pressure, friction-reducing, and anti-wear properties of the base lithium complex grease. In addition, the data show that the borated overbased calcium sulfonate detergent as additive in base lithium complex grease exhibited better anti-wear and extreme pressure properties than overbased calcium sulfonate detergent. This results were ascribed to the different boundary lubricant films formed on worn surface according the SEM and XPS analysis.