engleski

Preparation and characterization of oil based nanofluids with metal oxide and carbon nanoparticles

Nanofluids are the two-phase systems in which solid nanoparticles are dispersed in a very small amount in conventional base fluid, mostly water and oils but also other common solvents. Well-designed and carefully optimized, nanofluids show a number of advantages over conventional suspensions in various fields of application – as heat transfer fluids, transformer oils, metalworking fluids, etc. Here, very important issues are their good dispersibility and long-term stability. According to DVLO - Derjaguin, Verway, Landau and Overbeek theory on the stability of colloidal solutions, the basic precondition for stability obtaining is dominance of the repulsive forces between dispersed particles. There are two kinds of repulsion within the fundamental mechanism ; one is steric repulsion, and another is electrostatic repulsion. For achieving the steric stabilization, specially designed polymer molecules with the ability to adsorb on the surface of the particles that contribute to the additional increase of the steric repulsive forces are looked for. In this work, results of preparation of stable nanostructured fluids and some of its properties like thermal conductivity and lubrication will be presented and discussed. As solid phase, metal oxide and carbon nanoparticles were used ; base fluids were mineral transformer oil, as well as mineral, synthetic (poly-alpha-olefin, PAO) and vegetable (rapeseed oil) lubricating base oils. In order to achieve stability of the investigated two-phase systems, efficiency of the several types of commercially available surfactant as well as dispersant copolymers based on styrenemethacrylate monomers designed in our laboratory were tested.

mineral transformer oil, synthetic (poly-alpha-olefin), rapeseed oil, thermal conductivity, lubrication

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