Journal of Modern Processes in Manufacturing and Production, Volume 8, No. 4, Autumn 2019 37 Assessment the Wear Properties of Biodiesel-diesel Blends with the Addition of Copper Oxide Nanoparticles Hossein Khorshidnia 1 , Alireza Shirneshan 1,2* 1 Department of Mechanical Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran 2 Aerospace and Energy Conversion Research Center, Najafabad Branch, Islamic Azad University, Najafabad, Iran Email of Corresponding Author: arshirneshan@yahoo.com Received: November 19, 2019; Accepted: March 3, 2020 Abstract Normal lubricants such as petroleum, coals or natural gases are limited and will keep depleting due to high fuel consumption all over the world; so nano-lubricants can be considered as the alternatives. In the present study, copper oxide nanoparticles were mixed with biodiesel-diesel blends to evaluate the wear properties of the mixture by 4-ball wear tribo-tester. CuO nanoparticles (25, 50 and 75 ppm) were dispersed in B10, B20, and B50 blends. The results showed that with increasing the CuO nanoparticle fraction up to 50 ppm in the fuel blend, the wear scar diameter (WSD) decreased. Also, the results indicated that using copper oxide nanoparticles with a dosage of 75 ppm in the fuel blend causes a higher WSD compared with 50 ppm dosage. Based on the results, the scratches and roughness on the surface also decreased with an increase of biodiesel concentration and addition of nanoparticles up to 50 ppm in the fuel mixture. Keywords Wear Scar Diameter, Copper oxide, Nanoparticles, Wear 1. Introduction Lubricants with solid nanoparticles can reduce the friction coefficient and increase the load-carrying capacity of the lubricant fluid at the same time [1]. Nowadays, normal lubricants such as petroleum, coals or natural gases have been used, however, these sources are limited and will keep depleting due to high fuel consumption all over the world [2–4]. For a few components of an automobile such as fuel injectors and pumps, the lubricity issue is very important as they are lubricated by the fuel itself [5, 6]. In the automobile engine, the temperature of the fuel inlets is appeared to be above 60°C [7, 8] which also can influence lubricity. Especially, the lubricity of the fuel at fuel injectors and high-pressure fuel pumps could be greatly changed because of existing higher temperatures. The lubricity of conventional diesel fuel is poor so it is needed to use some material to improve the lubricity of diesel fuel. The nanoparticles itself is good as it has a self-repair function for the worn surface [9], in another word, it creates a protective layer, which is deposited at the contact area to improve tribological properties [10]. Some studies investigated the effect of using nanoparticles in lubricating oil on the tribological properties of the oil. According to Zhang et al. [11], the interposed layer between two surfaces will improve the smoothness of the relative movement and prevent damage in a variety of materials in many forms such as gas, liquid and solid. The new variant of lubricant developed when