Study of devitrification and sinterability of SiO2– CaO – K2O – ZrO2 and SiO2 – Li2O – ZrO2 system frits

Reference Presenter Authors
(Institution)
Abstract
11-008 Ana Paula Fonseca Albers Albers, A.P.(Universidade Federal de São Paulo); QUINTEIRO, E.(Universidade Federal de São Paulo); Trichês, E.d.(Universidade Federal de São Paulo); Freitas, L.d.(Universidade Federal de São Paulo); SiO2 – CaO – K2O – ZrO2 and SiO2 – Li2O – ZrO2 system frits are known for presenting a fast crystallization kinetics, making it possible to obtain vitroceramic glazes in a single heat treatment. However, the simultaneously occurrence of sintering and devitrification is a technological challenge in the production of this glaze typology. This work had as objective to study thermal transformations in these frits and to propose an optimized heat treatment cycle, aiming at the maximum densification with the crystallization of the interest phases. The frits were obtained by fusion at 1450°C and quenching in room temperature water. The systems were characterized to verify the transformations characteristic temperatures (differential thermal analysis - DTA), the crystalline phases developed (X-ray diffraction - XRD), final porosity and microstructure (scanning electron microscopy - SEM). The results indicates that the best alternative for a single heat treatment is the high speed heating (to inhibit crystallization) up to the system fusion, where the frits particles sintering occurs, achieving maximum densification. The crystallization occurs during the system cooling in the crystallization temperature plateau, optimizing the proportion of crystalline phases in the already densified system.
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