The Synthesis of Tricalcium Aluminate, 3CaO?Al_2O_3, using Low-temperature Combustion Synthesis

摘要

The paper starts from the premise that there is a predilection of metal nitrates with respect to certain fuels. Among urea, glycine and β-alanine, urea represents the optimum fuel for Al(NO_3)_3, whereas β- alanine is the most suitable fuel for Ca(NO_3)_2. There is presented - for the first time - a new version of the solution combustion synthesis, involving the use of fuel mixtures selected according to the reactivity of each metal nitrate. The synthesis of 3CaO?Al_2O_3 using a single fuel, urea, glycine orβ-alanine - as it is usually done in the initial version of the combustion synthesis - cannot be achieved unless subsequent thermal treatments are applied. In addition, in this case, the 3CaO?Al_2O_3 formation is always preceded by the preliminary formation of 12CaO?7Al_2O_3. The version we suggest - the use of a fuel mixture containing urea andβ-alanine - leads to the maximization of the exothermic effect associated to the combustion reaction and ensures the prerequisites for the direct formation of tricalcium aluminate as single phase, without being necessary any additional thermal treatments.