Effect of particle size of starting materials on the structure and properties of biogenic hydroxyapatite/glass composites

The work is devoted to investigation of porous glass-ceramic composite materials on the basis of biogenic hydroxyapatite and sodium borosilicate glass prepared from starting powders with different particle sizes (<50 ?m and <160 ?m). Starting hydroxyapatite/glass weight ratio was 1.0/0.46 and sintering temperature was ~800?C. Microstructural characterization of the surface and fracture of the samples revealed a decrease in sizes of grains and pores with decreasing the particle size of the precursor powder. However, porosity of the composites practically did not depend on the particle size and was equal to 32.5-33.0%. The same tendency was observed for the compression strength (66-67MPa). However, investigation of structural-mechanical properties using an indentation method, where dominant load is applied to the surface layers of sample, showed up the effect of the particle size of the starting powder on the mechanical properties of the composites: the smaller particle size, the higher mechanical properties.