Cold sintering of calcium carbonate derived from seashells
Keitaro Yamaguchi, Shinobu Hashimoto
Abstract
The cold sintering process (CSP) densifies ceramics powder at significantly lower temperatures (<300 °C) than used in conventional sintering. This is enabled with the application of a uniaxial pressure of several hundred mega pascals and a small amount of transient solvent that derives chemo-mechanical mechanisms. Therefore, by using this method, carbonates can be densified below their decomposition temperature. Since natural seashells are composed of more than 95% calcium carbonate (calcite and/or aragonite) along with organic components, most of them can be densified by CSP. In this study, two types of shells (clam and oyster) with different crystal phases of calcite and aragonite were used as starting materials and the mechanism of their densification by CSP was investigated. Differences in densification behavior between the two kinds of shells with and without heating pretreatment were also examined. Hardened bodies formed by CSP from seashells have potential uses as construction materials.