Properties of sintered zinc hydroxyapatite bioceramic prepared using waste chicken eggshells as calcium precursor

In the recent years, research on the development of hydroxyapatite (HA) using calcium from natural resources such as limestone, mammalian bones, marine shells and avian eggshells have been extensively studied. However, many studies focused on the properties of prestine HA without incorporation of dopants for strengthening effect. In this work, HA bioceramic was prepared using waste chicken eggshells calcium with addition of various concentrations of zinc dopant (1, 3 and 5 mol% Zn). In this work, the zinc-doped HA (ZnHA) was synthesized using a wet-chemical precipitation technique followed by oven drying and unixial pressing to formed green compacts. Pressureless sintering was carried out at 1200, 1250 and 1300 degrees C. The results showed that 5 mol% ZnHA (5ZnHA) exhibited the overall best properties after sintering at 1250 degrees C. The improvement in the fracture toughness was attributed to the formation of beta-TCP phase when zinc ion was incorporated into HA, combined with enhanced densification. It was observed that the HA grains were coarser and more densely when sintered at 1250 degrees C, indicating that there was strong interaction between pores and grain boundaries. However, fracture toughness slightly declined after sintering at 1300 degrees C due to rapid and abnormal HA grain growth.

Automated summary

In recent years, there has been extensive research on the development of hydroxyapatite (HA) using calcium from natural resources. However, most studies focused on pristine HA without incorporating dopants for strengthening. This study prepared HA bioceramic using waste chicken eggshells calcium with various concentrations of zinc dopant, and found that 5 mol% zinc-doped HA exhibited the best properties after sintering at 1250 degrees C. The improvement in fracture toughness was attributed to the formation of beta-TCP phase and enhanced densification.