Tribological Impact of Carbon Black Nanoparticles Obtained From Recycled Waste Tires as Additive to Motor Oil

Abstract Used tires are commonly stockpiled at landfills, taking up a vast space of land and leading to serious environmental issues, which makes recycling and finding better waste management strategies necessary. This study explores the potential role of recycled material extracted from waste tires in the lubrication industry by examining different properties of motor oil with the addition of carbon black (CB) particles obtained from used tires via the pyrolysis process. The CB particles have been added to motor oil at various concentrations (0.5, 1, 2, and 4 wt%), and several properties of the oil–CB lubricant mixture, such as tribological, rheological, and lubrication, have been investigated. After testing different concentration samples, the 2 wt% of CB in the motor oil showed the best tribological and rheological behavior compared to other samples. The improvement in motor oil performance with the addition of CB was evident in the mixed lubrication regime, with a more than 20% reduction in frictional and wear losses compared to the reference motor oil. This improvement in the oil's lubrication performance is attributed to the presence of CB particles between sliding surfaces operating as a third body that helps reduce the contact pressure and minimize solid–solid asperities contact. Therefore, this work demonstrates the viable role of carbon black recycled material in improving the lubrication properties of current motor oils.