Preparation of refractory calcium aluminate cement using the sonochemical process

• Published in: Materials research (São Carlos, São Paulo, Brazil) São Paulo, Brazil), 2013-07, Vol.16 (4), p.731-739
• Main Authors: Lourenco, R R, Angelica, R S, Rodrigues, J de A
• Format: Article
• Language: eng ; por
• Subjects: calcium aluminate cement; Castable refractories; Cements; Combustion; ENGINEERING, CHEMICAL; Firing; heat treatment; MATERIALS SCIENCE, MULTIDISCIPLINARY; METALLURGY & METALLURGICAL ENGINEERING; Phases; Raw materials; sonochemistry; synthesis; Tensile tests; Ultrasonic testing
• ISSN: 1516-1439; 1980-5373; 1980-5373
• DOI: 10.1590/s1516-14392013005000041

Calcium aluminate cements (CAC) were prepared by the sonochemical process, followed by heat treatment. The action of ultrasonic waves and the influence of thermal treatment conditions on two initial molar compositions of calcia:alumina of 1:1 and 1:2 were studied. The aqueous suspension containing the raw materials (A-50 alumina and CaO) was subjected to an ultrasonic bath, followed by drying and burning at 1000, 1200 and 1300 C. These cements were characterised by SEM, XRD and the mechanical strength was evaluated by splitting tensile tests, using commercial cement as a reference. The phases were semi-quantified using the Rietveld method. Results showed that hydration and sonochemical action increased the reactivity of the raw materials during firing and that phase formation depended on the thermal treatment conditions. The CAC cements were obtained at temperatures at least 200 C lower than those used in conventional methods, indicating the potential of this synthesis method, particularly for refractory castables.