02510nam a22001697a 4500082000800000100004000008245013400048264003800182300002600220500183400246650003602080700004102116856005702157942001302214999001902227952009402246  a621  aShah, Muhammad Usama Habib 9130721  aTribological analysis of Titanium Oxide (TiO₂) based BioLubricants at various operating conditions /cMuhammad Usama Habib Shah  aIslamabad : bSMME- NUST; c2025.  a80p.bSoft Copyc30cm  aMechanical 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.  aMS Mechanical Engineering        aSupervisor : Dr. Rehan Zahid9122313  uhttp://10.250.8.41:8080/xmlui/handle/123456789/55023  2ddccTHE  c614893d614893  00104070aSMMEbSMMEcEBd2025-09-26l0o621pSMME-TH-1173r2025-09-26w2025-09-26yTHE