Crystalline anorthite (CaO·Al2O3·2SiO2) powder was synthesized below 1000oC by a solution process employing a polymer carrier. Polyvinyl alcohol (PVA), having different molecular weights, was used as an organic carrier for preparation of the precursor ceramic gel. The PVA content, its degree of polymerization and type of silica sol had a significant influence on the specific surface area and morphology of the powder, and its crystallization behavior. The polymer content and its molecular length had an effect on the cation distribution in the solution and resulted in different crystallization behavior. Abnormally, omisteinbergite (CaO·Al2O3·2SiO2), which has the same composition as anorthite, was observed prior to crystallization of anorthite. A more porous morphology and higher specific surface area were obtained with a higher content of the PVA polymer. The milled, amorphous-type anorthite powder was densified to a relative density of 94% below 1000oC.

Keywords: Anorthite, Polyvinyl alcohol, Omisteinbergite, Crystallization, Densification