Milling of Nanoparticle Clusters for New Formulation Lubricants

A.T. Utomo, T. Addison, G. Konan, G. Ozcan-Taskin
BHR Virtual Pie Ltd., UK

Keywords: nanoparticle, lubrication, stirred bead mill, CFD


This paper comes from a large project working on the development of novel lubricants, which contain nanoparticles in their formulation, for the automotive industry. Two nanoparticles have been identified to reduce the friction coefficient in the boundary lubrication regime, i.e. tungsten disulfide (WS2) and molybdenum disulphide (MoS2). The dispersions of these nanoparticles in host oil have been carried out by using several devices and the stirred bead mill was chosen on account of its intensive energy input and ability to handle high solid concentrations. The milling in the stirred bead mill was carried out in a batch and re-circulation modes with working volumes of 0.25 l and 2.5 l, respectively, and two different grinding beads (0.5 and 0.8 mm) were used. The evolution of particle size distribution suggested that rupture was the dominant break-up mechanism. Besides that, CFD simulations were also carried out by using Eulerian-Eulerian multiphase model coupled with a population balance model to predict the flow patterns inside the milling chamber and particle size distributions of nanoparticles in the dispersions. Detailed comparison between CFD results and experimental data will be discussed.