CALCIUM PHOSPHATE POWDERS OBTAINED THROUGH THE PYROSOL METHOD

The decreasing in particle size, from micro to nano meter dimensions, allows the development of new materials, with improved properties. The pyrolysis method is a modern, unconventional synthesis method of various powders which leads to the preparation of very small (few nanometers) particles. This method is based on the spray-pyrolysis technique - pyrolysis of an aerosol obtained by ultrasonic spray. The present paper describes the evolution of the powders microstructure and composition with different processing parameters. Using different precursors, phosphate powders - hydroxyapatite (HAp) and beta-tricalcium phosphate (PTCP) - were synthesized In order to obtain homogeneous and fine powders of calcium phosphates the following experimental parameters were modified: the concentration of the solution of precursors, the flow of carrying gas, the frequency of piezoelectric ceramics ultrasonic vibration and the temperature of the pyrolysis furnace. The obtained powders were investigated using Thermogravimetric Analysis (or TGA) and Differential Thermal Analysis (or DTA) measurements, X-ray diffraction and scanning electron microscopy. The average crystallite size of powders was also estimated from diffraction data. The results are emphasizing that by the pyrosol method can be obtained powders with various compositions, consisting of spherical particles, with size within the nanometer range, which may have many medical applications.