Key-role of the recipe formulation in the solution combustion synthesis of monocalcium aluminate, CaAl2O4

Abstract

The preparation of monocalcium aluminate, CaAl2O4, via solution combustion synthesis is discussed in a side-by-side evaluation of the single-fuel and fuel-mixture approach. Single-fuel recipes based on urea or glycine, and corresponding metal nitrates, generated low combustion temperatures (480 °C and 748 °C), which did not enable the formation of CaAl2O4. Under identical experimental conditions, urea and glycine fuel mixture generated a much higher combustion temperature (1558 °C), which promoted the formation of single-phase CaAl2O4 directly from the combustion reaction. The as-prepared CaAl2O4 had a crystallite size of 60 nm and a BET surface area of 0.8 m2/g. Laser granulometry measurements evidenced that 90% of the CaAl2O4 particles were smaller than 28 µm. Combustion synthesis of CaAl2O4 powders requires a careful recipe formulation, as single-fuel approach and fuel-mixture approach may lead to different results in terms of combustion reaction evolution and phase composition of the resulted powder.