Chemical Preparation of the Binary Compounds in the Calcia‐Alumina System by Self‐Propagating Combustion Synthesis

Abstract

The binary compounds Ca3Al2O6 (C3A), Ca12Al14O33 (C12A7), CaAl2O4 (CA), CaAl4O7 (CA2), and CaAl12O19 (CA6) in the CaO‐Al2O3 system have been synthesized as high‐compound‐purity ceramic powders by using the self‐propagating combustion synthesis (SPCS) method. Materials characterization of the above‐mentioned phases was performed via powder X‐ray diffractometry (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy. The structural characterization of the C12A7 phase has been performed via Rietveld analysis on the powdered XRD samples. It has hereby been shown that, by using this synthesis procedure, it should be possible to manufacture high‐purity ceramic powders of CA, CA2, and C12A7 at 850°C, C3A at 1050°C, and CA6 at 1200°C in a dry‐air atmosphere.

Electronic band structure and carrier effective mass in calcium aluminates

“…Calcium aluminates (also known as high alumina cements) have a rich phase diagram which includes five lime-alumina compounds -3CA, 12C7A, CA, C2A and C6A [13,14,15,16,17,18,19,20,21,22,23]. Among them, 12C7A has the lowest melting point (1722…”

“…Such a superior refractory properties of these materials make them attractive for various applications as ceramics and glasses as well as in cement and steel industries [24,25]. Calcium aluminates have been grown by several techniques including solid state reactions (sintering), sol-gel technologies and self-propagating combustion synthesis, see [22,23,24] and references therein.…”

Novel Binary Calcia–Alumina Systems for Device Applications

“…At this stage, some products that are in the gaseous phase will spontaneously ignite at temperature of ~500°C. Ignition will increase the temperature of the dried foam produced to ~1300°C, leading to the formation of C12A7 single phase [30].…”

“…The CaO-Al2O3 phase diagram is composed of a series of binary compounds which are formed at various CaO to Al2O3 weight percent ratios [30][31][32]. As illustrated in figure 2.1, C12A7 is one of these binary compounds and melts congruently at 1392°C [23], [33], [34].…”

Study by DTA/TG of the formation of calcium aluminate obtained from an aluminium hazardous waste

“…These reactions involve the sintering of mixtures of oxides or carbonates at high temperature and long time. Recently sol-gel methods and self-combustion or polymeric precursor methods are used as an alternative way to prepare homogeneous precursor phases [3][4][5]. In these methods, pure reactants (salts, oxides) are employed as starting materials.…”