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.