Synthesis of Double Phosphates in a Combustion Wave
A. L. Vereshchagin, E. D. Minin
AltSTU, Biysk, Russia
Keywords: self-propagating high-temperature synthesis, calcium hypophosphite, double phosphates
Abstract
The composition of combustion products of calcium hypophosphite Ca(H2PO2)2 with sodium or potassium nitrates or nitrites as oxidizers in air at atmospheric pressure has been studied. Synthesis was carried out to obtain double phosphate of the composition Na(K) CaPO4. Mixtures of powders with zero oxygen balance were prepared using, if necessary, an additional amount of ammonium nitrate. The phase composition of condensed combustion products was studied by X-ray powder analysis. The mixtures burned stably at atmospheric pressure releasing P4O10 aerosol. The combustion products were melted white particles up to 1 mm in size. In condensed combustion products were found to contain the double phosphates NaCaPO4, Na2CaP2O7, K2CaP2O7, and KCaPO4 and calcium pyrophosphates Ca2P2O7.
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