Formulação, caracterização e análise de condutividade térmica de um compósito cerâmico a base de argilas e vermiculita

Abstract

This work accomplished the formulation, characterization and analysis of the technological properties and thermal conductivity of a ceramic composite based on clays and vermiculite. To perform this research, expanded (commercial) vermiculite and two kaolinite clays were used in the northern region of Piauí. The first step was to characterize the clays and the vermiculite, for which it was made the tests of Granulometric Analysis (AG), Plasticity Limit (LP), Liquidity Limit (LL), X-ray Fluorescence (FR-X) Thermogravimetry and Derivative Thermogravimetry (TG and DTG), in clays isolated and in formulations and of X-ray Diffraction (DR-X), Scanning Electron Microscopy (SEM) in clays and vermiculite. In order to determine the percentage of the components, in the formulation, the partial replacement of the clays by the expanded vermiculite in the contents of 5%, 10%, 15% and 20% of the total weight of the trace was considered. The specimens were extrusion formed at a vacuum of 25 in / Hg and measuring approximately 15.0 cm x 2.8 cm x 1.8 cm. After drying, the specimens were burned at four temperatures (950 ° C, 1050 ° C, 1150 ° C, 1250 ° C), with a heating rate of 2 ° C / min and a maximum temperature of 60 minutes. For the test specimens, the Technological Tests (ET) of Linear Retraction (RL), Water Absorption (AA), Apparent Porosity (PA), Flexural Rupture Stress (TRF) and Apparent Specific Mass (MEA) were performed. X-ray diffraction (DR-X), Scanning Electron Microscopy (SEM), Dispersive Energy Spectrometry (EDS) and Thermal Conductivity. Based on the results obtained it was possible to verify that the addition of vermiculite in kaolinite clays and burned at 1250 ° C, can add results of increase of mechanical resistance and reduction of thermal conductivity to ceramic composites, appearing as a possibility of use in refractory blocks for construction industry or for industry.