Self-propagating high-temperature synthesis of spinel-type pigments

Abstract

with aluminum powder ASD-4 and MgO and ZnO additives by the method of self-propagating high-temperature synthesis (SHS) is investigated. A blue and an ultramarine pigment are obtained. Their phase composition, IR spectra, and structural and color characteristics are studied. It is demonstrated that the SHS method is promising for producing heat-resistant spinel-type pigments of a blue-sky-blue color range.

Phase Transformations of Cobalt Oxides in CoxOy-ZnO Multipod Nanostructures via Combustion from Thermopower Waves

“…This unique color change followed the trace of the combustion waves on the surface. This phenomenon could be reasonably explained by combustion in the Co 3 O 4 –ZnO multipod/fuel composite that decomposed Co 3 O 4 –ZnO into CoO–ZnO 1− x …”

“…High temperature annealing near 900 °C can cause the chemical transition from Co 3 O 4 to CoO . However, this transition via annealing generally requires a long time and high‐temperature conditions.…”

Nanocrystalline Intermetallics in Al-Cu-Fe-Cr Decagonal Quasicrystalline Alloy

“…Moreover, the oxidation reaction being exothermic in nature, it generates heat and thus enhances the temperature of the reactants, which in turn augments the kinetics of reaction. This is analogous to self propagating high temperature synthesis for synthesizing spinels by solid state reactions [27]. Thus the mechanically activated surface coupled with the nanocrystallinity and, in the presence of the heat evolved due to exothermic reaction, has caused the easy formation of nanospinel even at moderate annealing temperature, i.e., in the case of 100 h MM is 500 C. In general, the calcinations temperature required is more than 1500 C for the formation of spinels from the mixture of individual oxides.…”

Size effect on the magnetic property of CoAl2O4 nanopowders prepared by reverse micelle processing

“…The 3 mode of the CO 3 2− anion appeared around 1384 cm −1 [24]. However, the bands due to the stretch vibrations of NO 3 − are evident at 1245 cm −1 [25,26]. The absorption band at 1097 cm −1 is probably due to CH-OH stretching vibration [22].…”

“…The spinels are complex oxides and represented by the general formula of A 2+ B 3+ O 4 . If the bivalent metal is cobalt with a small amount of magnesium, and the trivalent metal is aluminum, then the resulting pigments form blue to sky-blue color range [3]. The common methods reported for the synthesis of cobalt aluminate are sol-gel [4], EDTA chelating precursor [5], combustion [6,7], polymerized complex [8], glycine chelated precursor [9], hydrothermal [10], molten salt [11], polymer aerosol pyrolysis [12], and reverse micelle processes [13,14].…”