Synthesis, Characterization, and Tribological Behavior of Oleic Acid–Capped Calcium Borate Hydrate

In this article, a series of calcium borate, molecular formula 4CaO·5B2O3·7H2O (CB), was hydrothermally synthesized using borax and calcium nitrate. Furthermore, a of oleic acid–capped calcium borate (OAMCB) was prepared and characterized by means of Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), thermogravimetry (TG), and X-ray diffraction (XRD). In addition, the friction and wear properties of OAMCBs as additives in poly-alpha-olefin (PAO) were investigated using Cu-Cr-Zr alloy–AISI 52100 steel couples. Our results showed that the OAMCB improved the friction and wear by forming an interfacial boundary lubrication layer.