Design of alumina/β-eucryptite composite from alum sludge waste: physical properties, phase composition and coefficient of thermal expansion

Abstract

The main objective of this research is to design alumina/β-eucryptite composite with a low coefficient of thermal expansion (CTE) and then test its sinterability using alum sludge from water treatment plants as an alumina source. A suitable chemical method is used to extract alumina from alum sludge waste. In addition to extracted alumina, silica fume waste and lithium carbonate were used to prepare β-eucryptite. In order to prepare β-eucryptite, the phase formation is first to be adjusted. The prepared samples were fired at 800, 1000, and 1200 ºC, respectively.XRD, SEM, physical properties, and thermal expansion are used to characterize these samples. The results indicate that 1000ºC is the optimum temperature for eucryptite formation. The samples of alumina/βeucryptite containing 10, 20, 30, and 40% eucryptite are then prepared, and the influence of the heat treatment on the prepared composites is studied at temperature ranges of 1300, 1400, and 1500ºC. XRD analysis, microstructure, physical, and mechanical properties of alumina/β-eucryptite composites are investigated. The coefficient of thermal expansion (CTE) for various alumina/β-eucryptite samples at 1500ºC reduces with increasing β-eucryptite content, reaching 0.8098 x 10 -6 o C -1 . The results demonstrate that a composite with good mechanical properties and a low thermal expansion coefficient can be formed and utilized in a variety of different applications.