Cerâmica porosa obtida a partir de argilas utilizando secagem por congelamento.

Abstract

Porous ceramics are solid materials which have a combination of a continue structure and a network of open pores interconnected that may or not be permeated by a liquid or gas. Although several researches on porous ceramics have been carried out, the results are still scarce for the application of these materials in construction to improve acoustic and thermal properties at the same time. Among the research conducted, several have used porous ceramics, such as alumina, zirconia, mullite and cordierite and bioceramics. The aim of this study was to produce ceramic masses from clays, water, starch or gelatin for the production of porous ceramic blocks, using freeze drying. The raw materials were processed and then characterized by X-ray fluorescence (chemical analysis), X-ray diffraction (mineralogical analysis), particle size analysis and thermogravimetric analysis (TG / DTA). Subsequently, ceramic bodies were prepared with different types of clays, and the respective amounts of additives (water, starch and gelatin), in predetermined amounts. From these masses, specimens were made, which were subjected to heat treatment at a temperature of 1100°C with a heating rate of 5°C/min. After this procedure, the samples were characterized by X-ray diffraction, scanning electron microscopy (SEM) and analysis of physical and mechanical properties. From the results of X-ray diffraction it was observed in the samples, after heat treatment, the presence of hematite peaks, cristobalite, spinel and the first peaks of mullite. From SEM images it was revealed that the addition of starch and gelatin in larger proportions generate increased amounts of pores, whose data corroborate with those obtained from physical-mechanical analysis (apparent porosity and water absorption) being the best result obtained for the sample containing gelatin (A1GEL15) whosesimple compression resistance was greater than 2MPa.