Microwave Sintering of Nanocrystalline Hydroxyapatite

Abstract

Hydroxyapatite (HA), with the chemical constituent Ca10(PO4)6(OH)4, is the main mineral component of bone and teeth. This material is the most commonly used ceramic for bone replacement due to its superior biocompatibility that allows for intergrowth of new bones onto the material. However, the full exploitation of HA ceramics as implants has been limited due to the brittle nature of the material. Nanocrystalline microstructure has been found to enhance mechanical properties of ceramics. in this work, nanocrystalline hydroxyapatite, synthesized by the coprecipitation technique, was pressed into pellets with uniaxial press and consolidated via microwave sintering. Samples were easily sintered within a short time of 30 minutes at a temperature of 1 1000°CC and achieve a density up to 97% of the theoretical value. Dielectric measurements indicated signs of microwave coupling by HA above 9000°CC. Microstructural analysis showed that nanocrystalline grain size could be retained after densification. This paper reports the phase evaluation, microstructure and physical properties of the compacts upon sintering in the microwave.