In-situ synthesis of calcium borate/cellulose acetate-laurate nanocomposite as efficient extreme pressure and anti-wear lubricant additives.

In this study, calcium borate (CB) nanoparticles were in-situ grown onto cellulose acetate-laurate (CAL) template to prepare CB/CAL nanocomposite with uniform dispersion of CB nanoparticles by hydrothermal method. As-prepared CB/CAL nanoparticles were characterized by field emission scanning electron microscope, Fourier transforms infrared spectrometry, X-ray diffraction, and energy-dispersive X-ray spectroscopy. With average wear scar diameter (WSD), coefficient of friction (COF) and maximum non-seizure load (P_B) as evaluation criterions, CB/CAL, CAL, and CB were used as lubricant additives in poly-alpha-olefin (PAO) base oil to comparatively investigate the tribological properties with a four-ball tribotester. It was found that under the load of 490 N, the WSD and COF of PAO + CB/CAL (concentration of 0.6 wt%) reduced by 25.9% and 48.7%, respectively, and P_B increased by 79.6% compared with pure PAO base oil. CB/CAL nanocomposite exhibited superior lubricating performances than CB and CAL. In addition, the synergistic lubricating mechanism of CB/CAL nanocomposite as lubricant additive was explored.