Influência da incorporação de talco nas propriedades tecnológicas de massas para cerâmica vermelha

Abstract

This study aimed to evaluate the influence of talc incorporation at contents of 0%, 5%, 10%, and 15% in ceramic masses composed of two clays from Teresina, Piauí, Brazil. The raw materials were characterized in terms of their physical, chemical, mineralogical, and thermal properties using particle size analysis, Atterberg limits, residual content determination, X-ray fluorescence (XRF), X-ray diffraction (XRD), and thermogravimetric and differential thermal analysis (TG/DTA). The test specimens were shaped by uniaxial pressing using a regular metal mold with approximate dimensions of 80 mm × 10 mm × 10 mm and fired at temperatures of 800, 850, 900, and 950 °C. The technological properties evaluated included linear drying and firing shrinkage, loss on ignition, water absorption, apparent porosity, apparent density, and flexural strength. The macrostructure of the tested specimens was also examined. Subsequently, the specimens were assessed to determine whether they met the technical specifications established by the standards applicable to red ceramic products. The results demonstrated that talc incorporation influenced the technological properties of the ceramic masses, promoting reductions in apparent porosity and water absorption, as well as an increase in apparent specific mass under certain conditions. Total linear shrinkage ranged from 2.51% to 3.59%, while water absorption ranged from 11.62% to 14.74%. Flexural strength increased with firing temperature, whereas higher talc contents resulted in reduced mechanical performance. Overall, talc incorporation proved technically feasible for the studied ceramic masses, with the 10% talc content standing out as one of the conditions providing the best overall performance.