Combustion synthesis of calcium aluminates
Abstract
Commercial calcium aluminate cements for refractory use are known to contain various phases, the hydration behavior of which is interdependent and not fully understood. Hydration studies normally require that pure oxides be synthesized. Solid-state synthesis of single aluminates requires high temperatures and full conversion is not guaranteed. Moreover, it is difficult to obtain a compositionally homogeneous product with this method. The present work discusses a straightforward combustion synthesis technique to prepare submicron calcium aluminates using the corresponding metal nitrates-urea mixtures, at low temperature and short reaction times. The effect of the ratio oxidizer/fuel in the redox mixture was investigated, namely, to find out if urea contents below stoichiometry were enough to trigger the explosive combustion of the fuel and the subsequent decomposition of the salts, and how that ratio affected the phase formation and the characteristics, e.g., morphology and grain size, of the powder produced.
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Chemical synthesis and crystallographic data on iron doped cubic ye'elimite
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An investigation of fuel precursors and calcination temperature to obtain mayenite (Ca<inf>12</inf>Al<inf>14</inf>O<inf>33</inf>) powders by solution combustion synthesis
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Near-infrared emission of erbium-doped noncytotoxic calcium aluminate
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Deconvolution of thermoluminescence(TL) curve has evolved as a subject of its own merit and has attained a mature state. Unfortunately, even with the availability of multiple methods id analysis and numerous deconvolution software, the pitfalls are many. This paper presents a comprehensive deconvolution of TL curves of a typical phosphor, namely CaAl2O4:Sm3+ and once for all settle the prevailing myths on evaluation of intrinsic trap parameters (Activation energy, E and frequency factor, s) for crystalline phosphors. The TL curves are that of four different kinds of excitation (UV, x-ray gamma-ray and electron beam) as well as ten doses of gamma-ray excitation(0.5–50 Gy). Our results show multiple discrete trap levels within the bandgap of the CaAl2O4 lattice that are a potential source for developing novel afterglow phosphors and thermoluminescence dosimeters. Finally, we provide some simple guidelines to overcome the misconceptions that have been perpetually being propagated in the literature of TL and its applications.
Calcium aluminate cement in castable alumina: From hydrate bonding to the in situ formation of calcium hexaluminate
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