Mechanical resistance of sintered fluorapatite

Fluorapatite has a good aptitude to sintering in the temperature domain 900-1100 degrees C. The densification could reach 97%. At high temperatures, the densification is only hindered by grain coarsening. Fluorapatite is very sensitive to water vapour traces in the used gases. In the presence of water, we note the formation of hydroxyfluorapatite and the hydrolysis of calcium fluoride. The evolution of the tensile strength of sintered fluorapatite was studied as a fimction of temperature; such a characterization was made with the Brazilian test. This study showed that the mechanical properties decrease above 1000 degrees C under oxygen atmosphere, whereas, under argon atmosphere, the resistance increases with temperature and reaches its maximum value at 1050 degrees C.