Effect of spray drying treatment on the optical properties of Mg–Al spinel ceramics

Abstract

In recent years, Mg–Al spinel ceramic has been in the spotlight due to its large transparency range and good mechanical properties. The aim here, was to control the state of agglomeration of powder to improve densification behaviour and consequently optical and mechanical properties of the ceramics. Commercial powder with a small particle size was used and exhibits poor flowability, which was found to be detrimental to shaping and led to a translucent ceramic with an opaque crown. The powder was granulated by spray drying and the influence of the molecular mass of added polyethylene glycol on the granulate size, compaction and finally sintering behaviour was investigated. Special attention was paid to the differences in rheological behaviour of powders, which was thoroughly characterized with a FT4 powder rheometer. Agglomeration of powder improved in-line transmission at 650 ​nm up to 71% compared to 3% for ceramic from as-received powder.

Keywords

• Spinel
• Transparent ceramics
• Powder treatment
• Spray drying
• Powder rheology
• Post-HIP