The effect of TiO2 phase on the lubricating performance of sol–gel-derived TiO2 nanoparticles in fully formulated engine oil

• Published in: Journal of sol-gel science and technology Vol. 96; no. 2; pp. 327 - 335
• Main Authors: Cao, Lei, Li, Yang, Wan, Yong, Qi, Caixia
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.11.2020; Springer Nature B.V
• Subjects: Abrasive wear; Ceramics; Chemistry and Materials Science; Coefficient of friction; Composites; Friction; Friction reduction; Glass; Hardness; Inorganic Chemistry; Lubricants; Materials Science; Nanoparticles; Nanotechnology; Natural Materials; Optical and Electronic Materials; Original Paper: Industrial and technological applications of sol–gel and hybrid materials; Roasting; Rutile; Sliding contact; Sol-gel processes; Synthetic products; Titanium dioxide; Tribology; Nanoparticles; TiO; Engine oil; Friction; Calcination temperature; Wear
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-020-05354-4

This paper is devoted to investigate the friction-reducing and wear protection performance of TiO 2 nanoparticles as lubricant additive in fully formulated engine oil. The phase of TiO 2 nanoparticles, synthesized by a sol–gel process, was characterized by XRD. A four-ball tribometer was used to compare the friction coefficient and wear when lubricated by engine oil in absence and presence of TiO 2 nanoparticles. The surface chemistry of tribofilm was observed by XPS. The experiments showed that phase of TiO 2 nanoparticles plays great role in determining the friction-reducing and wear protection of engine oil containing TiO 2 nanoparticles. TiO 2 nanoparticles upon calcination at 300 °C are amorphous, showing lowest hardness and then best friction-reducing and wear protection performance in engine oil. Rutile nanoparticles obtained upon calcination at the temperature above 700 °C, on the contrary, act as abrasive in the sliding contact and present larger wear than the blank engine oil. Amorphous TiO 2 nanoparticles calcinated at 300 °C presents lowest average coefficient of friction and wear scar diameter in engine oil. Highlights The tribological performances of TiO 2 nanoparticles (NPs) in the engine oil are investigated. The phase of TiO 2 NPs plays role in determining tribological performance of oil with TiO 2 NPs. Amorphous TiO 2 NPs calcinated at 300 °C show lowest hardness and best wear protection in oil. Rutile NPs upon calcination at >700 °C act as abrasive and present larger wear than blank engine oil.