Dense lanthanum silicate oxyapatite ceramics obtained by uniaxial pressing and slip casting

Abstract

Lanthanum silicate oxyapatite (LSO) is a promising ion conductive ceramic material, which has higher oxygen ion conductivity at intermediate temperatures (600-800°C) compared to yttria-stabilized zirconia. Its mechanical properties, though important for any of its applications, have been scarcely reported. In this study, we compare apparent densification, open porosity and Vickers hardness of samples conformed by uniaxial pressing and slip casting and fired up to 1600°C. Colloidal processing was optimized for slip casting in order to get high green densities. At sintering temperatures higher than 1400ºC, both processing routes yielded comparable densities, although uniaxially pressed samples show slightly better mechanical properties, evidencing that slip cast ones already underwent a grain growth process.

Keywords

• apatite-type lanthanum silicates
• uniaxial pressing
• slip casting
• sintering
• microstructure