EFFECT OF PERMANENCE TIME AT THE MAXIMUM TEMPERATURE OF SINTERIZATION IN THE PHYSICAL-MECHANICAL PROPERTIES OF TEST SPECIMENS OBTAINED FROM COMPOSITIONS CONTAINING CLAYS AND ALUMINUM WASTE

Reference	Presenter	Authors (Institution)	Abstract
09-059	Karina Ruiz Silva	Silva, V.J.(Federal University of Campina Grande); Taveira, S.K.(Federal University of Campina Grande); Gonçalves, W.P.(Federal University of Campina Grande); Lira, H.L.(Federal University of Campina Grande); Neves, G.A.(Federal University of Campina Grande); Santana, L.N.(Federal University of Campina Grande); Silva, K.R.(Federal University of Campina Grande);	Mullite is an attractive ceramic material for structural and functional applications due to its excellent chemical, thermal, optical, electrical and mechanical properties. The objective of this work is to study the physical-mechanical properties of test specimens obtained from compositions containing clays and alumina waste at temperatures of 1300 and 1400°C, heating rate of 5°C/min and permanence time in the maximum sinterization temperature of 60, 120 and 180 minutes. The raw materials were characterized by chemical analyzes (by X-ray fluorescence), mineralogical (by X-ray diffraction - XRD), granulometric and thermogravimetric (TG/ATD). Then, compositions containing clays and alumina waste were formulated, obeying the stoichiometry of the 3:2 mullite, which were submitted to chemical, granulometric, thermal, mineralogical and morphological analyzes (by scanning electron microscopy - SEM). From the compositions, were specimens conformed by uniaxial pressing and subjected the heat treatments in conventional oven, and then the crystalline phases formed using the XRD standards were determined. In relation to the physical-mechanical characterization, the following properties were determined: water absorption, linear retraction, apparent porosity and mechanical resistance to flexion at three points. In general, XRD results showed that it is possible to obtain mullite as major phase from compositions containing clays and alumina waste, whose data corroborate the morphological analysis, which revealed crystals in the form of needles typical of mullite obtained from of clay minerals. However, this phase contributed to increase the mechanical strength of the specimens, thus favored, therefore, by the increase in temperature and the dwell time at the maximum sinterization temperature.
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