Exploring the Effect of Sintering Temperature on Hydroxyapatite Derived from Egg Shells

Effect of Temperature on Hydroxyapatite

Abstract

The term hydroxyapatite Ca5(P04)3(0H) is naturally occurring mineral and chemically identical to the mineral constituent of bones and solid tissues of mankind and mammals used for bone grafting, augmentation in maxillofacial surgery and in orthopedics as space filling material. However, the brittleness of pure HA materials narrows its application only to low-load bearing applications. Generally, for the improvement of the mechanical properties and the structural one, hydroxy apatite is subjected to the  sintering process. Thus, an optimization of the mechanical properties and micro structure of hydroxy apatite through a suitable choice of sintering parameters is under investigation. This paper presents the effect of sintering temperature on mechanical properties of hydroxy apatite compacts. A chemical precipitation method was successfully employed to prepare hydroxy apatite powder from waste egg shells. The eggshell derived HA is a cost effective bio-ceramic for biomedical applications and an effective material recycling technology. HA derived from egg shells and 5% organic additive was cold uniaxially pressed at 2500 psi for 3 min isothermal hold. The resulting compacts were sintered at different temperatures from 900-1100 °C for dwell time of 2 h. The samples were characterized by analyzing micro structural analysis, compressive strength, porosity and radial shrinkage. Compressive strength and porosity was increased with increase  in sintering temperature, while radial shrinkage was decreased with increasing sintering temperature. Structural analysis showed that inter connected pores were developed and a material with inter connected pores is thought to be a good candidate as scaffold material.