Análise comparativa do desempenho tecnológico de massas industriais de porcelanato

Abstract

Porcelain tile is a type of ceramic coating material that emerged in Italy in the late 1970s, developed over the following decade, and reached high performance in the production process in the 1990s. Brazil began importing porcelain tile from Italy and only started producing it domestically around 1996. Porcelain ceramic tiles have stood out in the market due to their low water absorption and, consequently, high mechanical strength, as well as their occasional resemblance to natural stone. Generally, the product's properties result from the low porosity achieved through material processing conditions (such as high degree of raw material grinding, high compaction force, and sintering temperature) and the potential of raw materials to form liquid phases during sintering (resulting in high densification). The formulation of mixtures for ceramic product manufacturing is a research stage associated with numerous tests at laboratory scale and later at semi-industrial scale, until a suitable mixture for industrial production is developed. Technically, the mixture is what differentiates ceramic tiles; it allows for the creation of products that, despite very low porosity, meet current standards and, above all, possess desirable visual aspects, especially flatness. The aim of this work was to evaluate industrial mixtures used in the production of porcelain tiles regarding microstructure, process performance, and mechanical properties, to compare them among themselves and with the parameters indicated in scientific literature. The mixtures were formulated and produced using raw materials available or viable in their respective manufacturing locations. The samples were subjected to physical and chemical characterization tests. The results reveal the existence of significant correlations between the different mixture compositions and the properties analyzed. The kaolinite content increases as the quartz content decreases, demonstrating that there are mixtures with a higher proportion of kaolinitic raw materials and others with more quartz, as reinforced by the chemical composition of the mixtures. High albite content was also observed in some mixtures. When this occurs, it becomes evident that the levels of microcline and phases containing alkaline earth oxides (such as talc, dolomite, and calcite) decrease. The medium and coarse contents of the particle size distribution varied among the industrial porcelain tile mixtures studied. For these samples, this observation may be more related to grinding process parameters, such as milling residue, than to chemical or mineralogical compositions. Generally, expandable mixtures had a firing threshold below 16 °C. Firing thresholds above 16 °C typically corresponded to non-expandable mixtures. This effect is more pronounced for unglazed porcelain tiles. The albite phase contributes to reducing the values of the pyroplasticity index along the temperature gradient. Kaolinite content above 20% also contributed to reducing pyroplastic deformation index values. Lower pyroplasticity index results are associated with samples that combined higher albite and kaolinite contents and lower levels of the [Microcline + Dolomite + Calcite + Talc + Hematite] group.