The use of boron-containing additives for synthesis of anorthite ceramic powders

Abstract

Anorthite ceramics have a great potential as a substrate material due to their low thermal expansion coefficient and low dielectric constant. For lowering the sintering temperature of anorthite ceramics several routes like employing additives, sol-gel method and the use of mechanochemical methods have been proposed.In this study, anorthite was synthesized by using mechanochemical methods and boron oxide addition. The raw materials used in this study were Sivas kaolin as a source for Al2O3 and SiO2, calcined alumina or Al(OH)3 as a source for Al2O3 and calcite powder as source for CaO. Phase characterizations of synthesized powders were performed by XRD using CuK radiation. Microstructural characterization was performed by SEM. Statistical experimental design techniques (SED) were used in order to determine and analyze the more important process variables for synthesizing anorthite ceramics. The results of screening experimental design clarified that the temperature was the most important process variable. Second most important process variable was grinding speed which was followed by additive amount and additive type. This study showed that both additive type and additive amount were important process variables because these two factors were related to each other.The effect of both additive use and grinding on anorthite synthesis helped decrease the synthesis temperature down to 900 oC.