Integrated XRD–SEM–EDS characterization of Al₂O₃ nano-enhanced engine oil and its influence on surface preservation of diesel engine cylinder liners

This study investigates the influence of aluminum oxide (Al₂O₃) nanoparticle-enhanced engine oils on the wear behavior of diesel engine cylinder liners. The aim is to evaluate the tribological performance and surface preservation capabilities of nano-lubricants under severe operating conditions. Cylinder liner samples were subjected to wear testing using four lubrication conditions of original unworn material, base engine oil, base oil with 1 g Al₂O₃ nanoparticles, and base oil with 2 g Al₂O₃ nanoparticles. A multi-modal characterization approach was employed, including X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy mapping, and optical microscopy. XRD analysis revealed substantial crystallinity degradation in the sample lubricated with base oil, while samples treated with Al₂O₃ nano-oils exhibited retained crystal structure, particularly at 2 g concentration. FESEM confirmed reduced surface damage with increasing nanoparticle content. EDS and elemental mapping demonstrated the formation of a protective Al₂O₃ tribofilm, particularly in the 2 g/L formulation, which minimized Fe exposure and oxidative wear. Optical microscopy corroborated these findings through visible preservation of the honing pattern in the 2 g sample. This work provides a comprehensive, experimentally validated case for the application of Al₂O₃ nano-lubricants in enhancing cylinder liner durability. The integrated use of structural, chemical, and morphological tools contributes novel insights to the field of nano-tribology and engine component reliability.