Low-temperature and single-step synthesis of fully-dense MgAl2O4 by reaction spark plasma sintering Al2O3 and MgO nano-oxides |
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| Institution: | 1. Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran, 31261, Saudi Arabia;2. Interdisciplinary Research Center for Advanced Materials, King Fahd University of Petroleum and Minerals, Dhahran, 31261, Saudi Arabia;1. Selvamm Arts and Science College, Namakkal, 637 003, Tamilnadu, India;2. Adiyamaan College of Engineering, Hosur, 635 209, Tamilnadu, India;3. Department of Physics, Periyar University, Salem, 636 011, Tamilnadu, India;1. Department of Chemistry, Osmania University, Hyderabad, 500007, India;2. Department of Chemistry, Malla Reddy Engineering College (Autonomous), Main Campus, Hyderabad, Telangana, 500100, India;1. Department of Engineering Chemistry, Andhra University, Visakhapatnam, India;2. Department of Chemistry, Adikavi Nannaya University, Rajahmundry, India;3. Department of Chemical Engineering, Andhra University, Visakhapatnam, India;4. Department of Chemistry, KGRL College, Bhimavaram, India;5. Department of Chemistry, P. R. Government College (A), Kakinada, 533001, A. P., India;6. Department of Engineering Physics, AUCE (A), Andhra University, Visakhapatnam, India |
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| Abstract: | The availability of commercial nano-powders and the rapidly maturing powder metallurgy technology have enabled researchers to develop advanced ceramics, with tailored microstructure and improved properties. However, a major challenge in the production of MgAl2O4, from Al2O3 and MgO, is the relatively high-volume expansion (5–8%) accompanying spinellization. This study demonstrates the possibility to prepare fully-dense and single-phase magnesium aluminate spinel, at low temperature and in short time, without the use of a sintering aid. This is achieved by sonication of magnesia and alumina followed by reaction spark plasma sintering. X-ray powder diffraction and scanning electron microscopy methods were used to characterize the starting nano-powders, sonicated powder mixture, spinel formation, and fractured specimens. The values of HV, K1c, and GIC were obtained from indentation measurements. The chemical composition, the SEM images, and the X-ray maps of magnesium and aluminum, confirmed the stoichiometry and homogeneity, at nano scale, of the densified specimens. The fully dense spinel, obtained at 1300 °C and 30 min, had average grain size of 40.92 nm, HV of 17.29 ± 0.185 GPa, K1c of 2.129 ± 0.106 MPa mm1/2, and GIC of 15.488 J/m2. |
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| Keywords: | MgO nano-oxide Spinellization Magnesium aluminate spinel Reaction sintering |
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