02423nam a22001577a 4500 621 Shah, Muhammad Usama Habib 130721 Tribological analysis of Titanium Oxide (TiO₂) based BioLubricants at various operating conditions / Muhammad Usama Habib Shah Islamabad : SMME- NUST; 2025. 80p. Soft Copy 30cm Mechanical components operating under boundary lubrication experience high friction and wear which lead to energy losses and faster equipment damage. Traditionally, mineral oil–based lubricants have been used to overcome these issues but their declining availability and environmental impact have encouraged a shift toward renewable, eco-friendly bio-lubricants. While bio-lubricants are sustainable and biodegradable, their performance often declines at high temperatures and heavy loads due to lower thermal stability and inconsistent wear resistance. Using nanoparticles in bio-lubricants helps improve their performance by forming a protective film, lowering surface contact and maintaining stable friction behavior. Titanium dioxide (TiO₂) was chosen in this study for its chemical stability, low toxicity and ability to form protective tribofilms. Cottonseed Oil (CSO), Rattan Jot Oil (RJO), Waste Cooking Oil (WCO) and synthetic Polyalphaolefin (PAO) were tested with and without 1 wt% TiO₂ using a four-ball tribometer at 75°C and 100°C under 147N and 392N loads. The coefficient of friction (COF), wear scar diameter (WSD) and surface roughness were measured. Worn surface analyses were conducted using an Olympus DSX-1000 microscope. RJO+TiO₂ showed the best performance, achieving a 65% reduction in COF and 37.5% reduction in WSD at 100°C–147 N. CSO+TiO₂ also performed strongly, with a 62% reduction in WSD, while WCO+TiO₂ gave the worst results, with 111% higher WSD and 36% higher COF under 100°C–392 N due to nanoparticle agglomeration and unstable lubrication films. These results show that TiO₂ nanoparticles can significantly enhance the friction and wear performance of bio-lubricants, with RJO+TiO₂ emerging as the most reliable choice for high-load boundary lubrication applications. MS Mechanical Engineering Supervisor : Dr. Rehan Zahid 122313 http://10.250.8.41:8080/xmlui/handle/123456789/55023 ddc THE 614893 614893 0 0 0 0 SMME SMME EB 2025-09-26 0 621 SMME-TH-1173 2025-09-26 2025-09-26 THE