Abstract
In the present investigation, the nano- and micro-sized powders were synthesized by stoichiometric contents of magnesium and aluminum nitrates using combustion–oxidation method. The study was conducted over a wide range of operating conditions, in terms of fuel ratio and calcination temperature. The characteristics of magnesium aluminate powders were studied by differential thermal analysis and thermogravimetry (DTA–TG), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. The thermal stability of powders was evaluated by calcination at different temperatures. Differences of the specific surface areas were related to the composition and crystallite size. The importance of fuel ratio and calcination temperature to achieve the nano- and micro-sized oxide was discussed in detail. The fuel ratio of 0.56 and calcination at 800 °C provided the conditions to achieve the nano-scale magnesium aluminate powders, smaller than 20 nm. The application of presented algorithm can be an important tool for control of particle size in the nano- and micro-scale.
Highlights
Magnesium aluminate (MgAl2O4), which is a ceramic composition, is employed at different engineering fields
The differential thermal analysis and thermogravimetry (DTA–TG) curves of precursors synthesized with fuel ratios of 0.56 and 0.75 are shown in Figs. 2 and 3, respectively
The weight losses of 69.0 and 58.0 wt% are recorded for precursors synthesized using fuel ratios of 0.56 and 0.75, respectively
Summary
Magnesium aluminate (MgAl2O4), which is a ceramic composition, is employed at different engineering fields. The important properties that make magnesium aluminate as a superior material are high melting point (2135 °C), relatively low density (3.58 g/cm3), excellent transmittance in the wavelength of 0.25–5.0 m, high bending strength (180 MPa) and Vickers hardness (16 GPa), inertness in acidic environments, low thermal expansion coefficient (9 10 6 (°C) 1 between 30 and 1400 °C), and high thermal shock resistance [1]. The major applications of this composition can be summarized as: (i) catalyst support especially for high temperature reactions [2,3]; (ii) fabrication of refractory [4,5]; (iii) manufacture of optical devices and sensors [6,7]; (iv) advance applications such as electrochemical fields, dentistry, and reinforcing fibers [6].
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