Desenvolvimento de engobe impermeável para ciclo de queima rápida

Abstract

The growing Brazilian market in the area of ceramic coatings and the need to know better the properties of the engobes, motivated this study, whose objective is the development of waterproof and opaque engobes for fast burning cycle. This work was done in the company Elizabeth Porcelanato LTDA - UNIT 3 belonging to the group paraibano Elizabeth, founded in 1984, being the largest group of the sector in the state of Paraíba. In order to better understand the influence of some raw materials, different formulations were proposed based on modifications made in accordance with the study of their properties. The present work was basically divided into two stages, where the first one was to develop a waterproof engobe through the addition of diopside in its formulation, in this way, after a visual analysis made according to the procedure described in NBR13818 and water spot test, it was observed that test B presented better texture and greater impermeability when compared to tests A and C, choosing test B as a new standard (STD-2). The second stage consisted in the modification of only 3 raw materials in the formulation with the objective of evaluating the influence of each of them in the engobe, they are: feldspar, kaolin and zirconium silicate. In addition to observing the behavioral differences in the engobe suspensions, was performed water absorption, linear retraction, water stain, x-ray fluorescence chemical analysis, dilatometric analysis, calorimetric analysis and evaluation of formulation cost. The results of dilation for the STD-1, STD-2, T1, T2 and T3 tests were: 73,5x10-7°C-1, 74x10-7°C-1, 73x10-7°C-1, 73,7x10-7°C-1, 72x10-7°C-1, respectively, showing that the modifications made in the formulations were very small, therefore, insufficient to show significant variations in dilation. It was verified that the addition of diopside in substitution of feldspar resulted in lower water absorptions, that is, formulated engobes have lower porosity in relation to STD-1, consequently smaller retractions. It was found that the higher the proportion of zirconium silicate in the composition of the engobe, the more opaque and the higher the added value this will be. This was confirmed by the analysis of E and observed in T2, which contained in its composition about 8% of zirconium silicate in relation to T1 with 6%, T3 with 6.5% and STD-2 with 7%, consequently, the T2 in relation to the others did not present savings for the company.