Microstructural dependence of Young's and shear moduli of P 2O 5 glass reinforced hydroxyapatite for biomedical applications

Abstract

P 2O 5 glass reinforced hydroxyapatite composite materials were prepared through a liquid-phase sintering process. Secondary phases, β- and α-tricalcium phosphates ( β-TCP and α-TCP), were formed in the microstructure of the composites, due to the reaction between the liquid glassy phase and the hydroxyapatite matrix. The dynamic Young's modulus ( E) and shear modulus ( G) of these composites were determined using an impulse excitation method. By applying the Duckworth–Knudsen equation, the elastic property results were correlated with the relative proportion of β-TCP and α-TCP phases and with the porosity percentage present in the microstructure. Glass reinforced hydroxyapatite composites showed lower Young's and shear moduli than unmodified hydroxyapatite, mainly due to the presence of β-TCP phase. The Duckworth–Knudsen model demonstrated an exponential dependence of E and G modulus with porosity and mathematical equations were derived for composite materials with porosity correction factors ( b) of 4.04 and 4.11, respectively, indicating that porosity largely decreased both E and G moduli.