Surface modification for dispersion stability of novel FAl₂O₃-POE nanolubricant using functional SiO₂

The presence of a hydroxyl group on the surface of Al2O3 is responsible for the low level of stability of Al2O3-based nanolubricant. This paper aims to illustrate how the SiO2 functionalization approach can be used to modify the surface of Al2O3 nanoparticles. The effects of four different functionalization treatments on Al2O3 on the dispersion stability of FAl2O3-Polyolester (POE) nanolubricant were found to be significant. There are four samples with SiO2:Al2O3 ratios of 15:85, 30:60, 45:55, and 50:50%, respectively. Each sample was mechanically stirred for 120 min for adsorption process. Then, each sample received a sub-inter critical annealing treatment at 120 °C in the furnace for 180 min, after which the samples were chilled using the gradual cooling approach to avoid thermal shock on the FAl2O3 nanoparticle surface. Newly synthesized FAl2O3 was dispersed in POE lubricant for 30 min with a magnetic stirrer and then ultrasonicated for 100 min to prevent agglomeration. On day 1 and day 15, dispersing stability was examined using the UV visible spectrophotometry method to verify the wettability of FAl2O3 nanoparticles enhancement. The results reveal that increasing the SiO2 ratio in the functionalization process enhances the dispersion stability of FAl2O3-POE nanolubricant. The findings suggest that FAl2O3-POE sample with a 50:50 ratio has the best dispersion stability, as shown by the highest absorbance ratio value of 0.945.