Estudo da obtenção de cerâmica composta de alumina e beta alumina sódica utilizando-se resíduo cerâmico de velas de ignição e pó químico de extintores de incêndio

Abstract

Ceramic materials the alumina base are large industrial applications. They are required for these products, specific characteristics obtained by following strict criteria during the manufacturing process. However, after life, not always these products are reused by a suitable waste management process. In ceramist context, advance research aimed at the reuse of waste aimed at obtaining ceramics and composite materials, with marked reduction of conventional raw materials. Aiming to generate scientific, technological and environmental contribution, this work studied to obtain a composite of alumina ceramic (Al2O3) and sodium beta alumina (NaAl11O17 ), and as starting materials the residue of the ceramic insulator of spark plugs, as a source alumina (Al2O3) powder and unusable sodium bicarbonate (NaHCO3) of fire extinguishers, as a source of sodium oxide (Na2O). The final ceramic product was obtained from a conventional mixture of sodium aluminum oxide in appropriate molar proportions. Sample spark plugs were obtained, discarded by lifetime, specific to a manufacturer, which, after passing through mechanical stress (grinding, magnetic purification, washing, drying and grinding the high energy), which resulted in residue powder with ceramic content of 84.34 % alumina (Al2O3), found by FRX chemical analysis, the phases present and identified by DRX. The dry chemical fire extinguisher, baking soda-based (NaHCO3) with expired, was obtained through direct collection of the waste generated during maintenance. Subjected to heat treatment at 120 °C , the NaHCO3 powder was decomposed in sodium oxide ( Na2O), which, subjected to chemical analysis (FRX) and mineralogical (DRX) revealed a content of 86.62 % sodium oxide (Na2O) . In the following steps the experimental procedure, chemical formulations were made on a molar basis of the starting material (1:9, 1:10 and 1:11 de Na2O/ Al2O3) inclusion of additives, milling parameters, sieve analysis, dilatometry, conformation of specimens, sintering in firing steps at 800 °C , 1000 °C and 1.200 °C with varying stays 30 , 60 and 120 minutes in each of the levels. The characterization of the final product was made by the following physical tests: water absorption, porosity, linear shrinkage, mineralogical analysis by DRX and microstructural analysis by MEV. A higher formation of sodium beta alumina (NaAl11O17), in sintered specimens in levels of 1.200 °C and 120 minutes, despite the prevailing coexistence of alpha phase alumina (Al2O3). From the results obtained opens up prospects for the reuse of waste studied in this work, the potter context and in other technological areas.