Replacement of hydroxyapatite from chicken eggshell waste for ceramic properties improvement

The chicken eggshell waste from food processing was synthesized as the hydroxyapatite for fluxing agent replacement in ceramic manufacturing. The main fluxing agents in Thailand ceramic manufacturing are natural potash feldspar (k-feldspar) and animal bone ash. To overcome the problems of inconstant properties and the lack of k-feldspar, the hydroxyapatite from chicken eggshell waste was selected as fluxing agent for the enhancement of the ceramic product. In this work, the hydroxyapatite with 0, 5, 10, and 15 wt% was replaced with the k-feldspar in the ceramic samples. The results revealed the physical and mechanical properties of the ceramic samples with various hydroxyapatite contents were investigated after heat treatment in the temperature range of 1000–1200 °C. The ceramic samples added with hydroxyapatite have higher linear shrinkage and bulk density as compared with the ceramic sample without hydroxyapatite. The apparent porosity and water absorption decreased to near zero after the heat treatment at a temperature of 1200 °C. Moreover, the results showed that the physical properties affected the mechanical properties improvement after the hydroxyapatite addition and heat treatment process.