| The goal of this project is the development of iron nanofluids for magnetic and thermal applications. The specific contribution of this project to the advancement of science is the detailed study of scale-up procedures for the preparation of iron nanofluids using three different methodologies. Emphasis is placed on engineering the particles such that they meet certain morphological characteristics for microfluidic device development. A two-step approach is explored to formulate the nanofluids, starting with nanopowder development followed by the dispersion of synthesized nanopowders in a carrier fluid. The processing of nanopowders is carried out by optimizing the microemulsion, coprecipitation, and polyol synthesis processes. To study the effect of different processing parameters on the structure, phase, particle, and agglomerate sizes of the powders, the precursor concentrations, pH, temperature, processing time, stabilizers, surfactants, and polymers are varied. In-situ growth mechanisms of crystalline iron and iron oxide nanoparticles are discussed. The results show crystalline phases of metallic and oxide phases of iron with varying particle sizes (5-200 nm) and morphologies obtained under a variety of conditions. After nanopowder synthesis, the sonochemical technique is used to disperse powders in a base fluid to develop magnetorheological fluids (nMRF) and thermal fluids. The yield strength, flow, and thermal conductivity characteristics are measured for the developed fluids with varying solids loadings. The results show an enhancement of ∼20% in thermal conductivity for iron nanofluids over base fluids without the application of an external field. The nMRF's show maximum yield strength of ∼4 kPa with the ability to flow through microchannels. |
