Synthesis and tribological studies of nanoparticle additives for pyrolysis bio-oil formulated as a diesel fuel

The tribological behaviour of pyrolysis bio-oil with a synthesized nano-Lanthanum oxide (La₂O₃) additive was evaluated using a point contact four ball tribometer under different frictional conditions. Results were compared against a micro (μ)-La₂O₃ additive and an un-additised bio-oil as a control. The results show that nano-La₂O₃ impregnated bio-oil had better tribological properties than the control groups. Under the operating loads, the optimum nanoparticle concentration within the bio-oil was investigated. At these levels, the combined action of adsorbed bio-oil films on the worn surfaces and the bearing effects of the nano-La₂O₃ minimized friction and wear. The tribo-mechanisms were ascribed to adhesive wear as a result of lubrication starvation under high loads, and abrasive wear at high rotational speeds as a result of combined deformation and aggregation of the nano-La₂O₃ particles. - Highlights: • The tribological properties of pyrolysis bio-oil with (μ & n) La₂O₃ were assessed. • Nano-La₂O₃ was synthesized with diameters of approximately 20–1000 nm. • Bio-oil w. 1% nano-La₂O₃ was the optimum additive & concentration for tribological properties. • 1% nano-La₂O₃ reduced corrosive wear with stable lubrication film for test conditions. • Wear mechanisms were predominately adhesive for higher loads and abrasive for higher speeds