Synthesis of Calcium Hydroxyapatite‐Tricalcium Phosphate (HA‐TCP) Composite Bioceramic Powders and Their Sintering Behavior

Composite (biphasic) mixtures of two of the most important inorganic phases of synthetic bone applications‐namely, calcium hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 (HA)) and tricalcium phosphate (Ca 3 (PO 4 ) 2 (TCP))‐were prepared as submicrometer‐sized, chemically homogeneous, and high‐purity ceramic powders by using a novel, one‐step chemical precipitation technique. Starting materials of calcium nitrate tetrahydrate and diammonium hydrogen phosphate salts that were dissolved in appropriate amounts in distilled water were used during powder precipitation runs. The composite bioceramic powders were prepared with compositions of 20%‐90% HA (the balance being the TCP phase) with increments of 10%. The pellets prepared from the composite powders were sintered to almost full density in a dry air atmosphere at a temperature of ~1200°C. Phase‐evolution characteristics of the composite powders were studied via X‐ray diffractometry as a function of temperature in the range of 1000°‐1300°C. The sintering behavior of the composite bioceramics were observed by using scanning electron microscopy. Chemical analysis of the composite samples was performed by using the inductively coupled plasma‐atomic emission spectroscopy technique.