One of the most important challenges industry has always been facing is the wear phenomenon. Wear is the cause of huge deteriorations in parts and results in a drop in performance and lifetime of different machines. Therefore, finding solutions to reduce friction coefficient and wear is of special importance. The present research aims at numerical and experimental investigation of friction coefficient and wear in the presence of nano-lubricants. In the numerical section, to tackle different scales of contact components, two sub-models are developed. In the first one, contact of asperities is modeled and the properties of contact surfaces are taken into account. Second sub-model simulates nano-particles in the contact region. Furthermore, a series of experiments are conducted under different loads, speeds, and different values for Zinc Oxide nano-particle weight percent using a pin-on-disk test rig. Results show that predicted friction coefficient and wear volume in theory are reasonably in agreement with experimental results. It was found that adding nanoparticle to the lubricant can be beneficial in terms of friction reduction.

The main goal of this study is to present a model to investigate the effect of nano-particles’ weight fraction on the friction coefficient of rough contact in the mixed-lubrication regime. Experimental testing involves pin-on-disk measurements of the friction coefficient with CuO nano-particles added to engine oil. Theoretical analyses involve developing a method for treating an EHL line contact with provision for surface roughness that takes into account the load-carrying capacity of surface asperities, lubricant, and nano-particles. Results show that theoretical and experimental results for friction coefficients are in good agreement. A parametric study is conducted to investigate effect of load, the geometry of the nano-particles, and their mechanical properties as well as their weight fraction on the friction coefficient.

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