Detonation Consolidation of NiFe/SiO 2 and Co/SiO 2 nanocomposites
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Detonation Consolidation of NiFe/SiO2 and Co/SiO2 nanocomposites Xinqing Ma1, Y. D. Zhang1, S. Hui1, Mingzhong Wu1, Shihui Ge1, W. A. Hines2, J. I. Budnick2, B. M. Cetegen3, and S. Y. Semenov3 Inframat Corporation, 74 Batterson Park Road, Farmington, CT 06032, U.S.A. 1 Inframat Corporation, 74 Batterson Park Road, Farmington, CT 06032 2 Department of Physics and Institute of Materials Science, University of Connecticut, Storrs, CT 06269, U. S. A. 3 Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269, U. S. A. ABSTRACT Consolidation of nanostructure magnetic particles is required not only for manufacturing bulk component, it is actually a fundamental requirement for obtaining novel magnetic properties from the material. Consolidation (assembly) of nanoparticles to full density without deteriorating their nanostructure (size and morphology) is a big challenge. Here we present the consolidation experiments of NiFe/SiO2 and Co/SiO2 nanocomposites via detonation consolidation. This approach is based on the explosive pressure created when an acetylene and oxygen mixture gas fires in a sample containing tube, the very high hypersonic propulsion force makes nanoparticles deposit onto the target. Depending on the powder morphology and operation conditions, the density of the consolidated sample can reach over 91% of the theoretical density of the bulk materials. X-ray diffraction experiments on the samples before and after consolidation indicate that the denotation consolidations can be optimized such that it does not cause any phase transition. However, a particle size increase was observed. Static magnetic studies carried out on the samples before and after detonation operation shows that the saturation magnetization does not. This indicates that the operation does not cause an oxidation of the nanopowders. These experiments show that detonation approach is a good candidate for consolidating magnetic nanoparticles. INTRODUCTION Nanocomposite fabrication provides a new opportunity to develop novel soft magnetic materials. In a metal/insulator nanocomposite system, its resistivity can be dramatically increased compared with conventional metallic alloys, leading to significantly reduced eddy current loss. Meanwhile, the exchange coupling between neighboring magnetic nanoparticles can overcome the anisotropy and demagnetizing effects, resulting in much better soft magnetic properties than conventional materials.1,2 In pursuit of this idea, a large number of metal/insulator nanocomposite powder systems have been explored based on powder processing, which is advantageous for mass production of nanocomposite materials.3-5 However, densifying nanoparticles into a bulk material while retaining their nanostructure is a big challenge. Among the consolidation approaches,6,7 detonation compaction is a promising one.8-12 The detonation gun spray process, referred to as the D-gun process, has been widely used in various industrial applications where a layer with high strength, high hardness and high
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