Synthèse et caractérisation d’une mullite a base de matières locales pour substrats de silicium photovoltaïque

Abstract

Mullite (3Al2O3-2SiO2 and 2Al2O3-SiO2), is one of the most studied and used ceramics. Its applications are very diverse and range from refractory to technological products. Under air and atmospheric pressure, it’s stable thermally and chemically from ambient temperature upto its melting temperature. These interesting characteristics such as it’s very limited creep sensitivity, it’s very good thermo mechanical properties, it’s relatively low thermal expansion coefficient which gives it good resistance to thermal shocks. In this work, we have valorised local raw materials by the synthesis of a mullite from Algerian kaolin (DD1, DD2, and DD3) and a recycled alumina. First, we studied the raw materials powders (kaolin and aluminium slag) to understand the phases transformations during firing. The results obtained show the formation of primary mullite as well as cristobalite at 1400 °C. We enriched these kaolin’s by adding aluminium slag to obtain secondary mullite. Primary mullite is formed from the transformation of metakaolinite while secondary mullite results from the reaction of slag alumina with the excess of silica of the kaolin. The results obtainedat 1400°C show that the quantity of the mulllite formed is more important. The study of the rheological behaviour allowed us to choose the kaolin suitable for the casting. The samples obtained after sintering present good mechanical characteristics.