Estudo da viabilidade, em termos de desempenho térmico, de placas cerâmicas com a inserção de 8% de aerogel sintetizado pelo método sol-gel à pressão ambiente

Abstract

This work has the objective of evaluating the thermal performance of ceramic plates with the insertion of 8% of airgel synthesized by the sol-gel method at ambient pressure. The airgel, after being synthesized, was chemically characterized by infrared spectroscopy and physically by the Multimolecular Adsorption Theory - BET. Four ceramic plate formulations were made: one composed of 100% red clay, the other composed of 92% red clay and 8% aerogel, a third consisting of 100% white clay and one containing 92% white clay and 8% aerogel. The ceramic plates were manufactured by the following process: dry milling, uniaxial pressing forming at 15 MPa, 48 hour drying and monocoima at 950ºC, 1100ºC and 1300ºC. After being produced, these were characterized mechanically by the three-point flexural strength test. The samples that reached the minimum required by current regulations for this property were characterized chemically, physically and thermally, the others were discarded from the study. The chemical characterization was carried out by X - ray diffraction analysis. The physical characterization was ensured by scanning electron microscopy (SEM), water absorption, apparent porosity, apparent density, linear burning retraction and fire mass loss. The thermal characterization was carried out by the thermal conductivity test. The results indicated that airgel synthesized at ambient pressure does not show reproducibility. The synthesis demonstrated chemical and physical success, confirmed by the silanol, siloxane and methyl silane grouping bands and the mesoporous classification, respectively. The plates with white clay showed satisfactory mechanical resistance, while the red ones did not reach the minimum required by the Brazilian standard. The addition of airgel in the white base ceramics increased water absorption by 20.68%, the apparent porosity by 12.61%, the burning retraction by 6.85% and the loss of mass by fire by 8.77%. 17.41% the flexural strength, 14.70% the apparent density and 7.85% the thermal conductivity. Therefore, the insertion of 8% airgel in ceramic plates is not feasible in terms of thermal performance given the high costs for the production of airgel.