Preparation of hydroxyapatite ceramic through centrifugal casting process using ultra-fine spherical particles as precursor and its decomposition at high temperatures

Ultra-fine hydroxyapatite (HAp) powder with a diameter of about 10 nm was used as precursor for preparation of HAp ceramic. The precursor hydroxyapatite was single phase and highly crystallized without any additional thermal treatment. Highly densified HAp ceramic was fabricated through centrifugal infiltration casting (CIC), followed by pressureless sintering. The relative densities of compacts prepared at 1100 degrees C and 1200 degrees C were 77.8% and 94.1%, respectively. SEM micrographs of HAp ceramic sintered at 1100 degrees C showed a porous microstructure with a grain size of 1 mu m. HAp ceramic fabricated at 1200 degrees C revealed a dense microstructure with nano-sized spherical alpha-TCP distributed at grain boundaries and triple points. The mechanism of decomposition from HAp to alpha-TCP at 1200 degrees C was discussed on the basis of SEM, XRD and FTIR results.