Production of Cement Based on Calcium Aluminate by Means of Solid State Reactions

Abstract

Through powder techniques and in situ solid state reactions, a refractory cement CaAl2O4-based was fabricated, using CaCO3 extracted from chicken eggshells and Al as precursor materials. To reduce the particle size and achieve a homogeneous mixture, the powders were subjected to high-energy milling in a planetary mill. The powders resulting from the grinding were compacted to form cylindrical tablets. These samples were pressureless sintered in air. A particle size distribution analysis indicates that they were obtained from the grinding particles ranging in size from nanometers to 2 microns. Differential thermal analysis indicates that the decomposition of CaCO3 begins at 953 K and ends at 1073 K, a situation confirmed by X-ray diffraction analysis, the latter also indicating that the formation of the CaAl2O4 crystalline phase is completed at 1773 K. The microstructure observed by scanning electron microscope shows equiaxial grains in the form of flakes and sizes from 1 to 2 microns. The average density and hardness of the material was 3.08 g/cm3 and 430 HV, respectively. With regard to thermal shock tests, the material showed cracks from cooling with temperature gradients of 873 K.