Fabrication of composites based on Ca 10 (PO 4 ) 6 (OH) 2 and SiO 2

The aim of the work described in this paper was to make a composite consisting of hydroxyapatite as bioactive matrix and SiO 2 as bioinert component. Five different systems were formed where the content of SiO 2 in the hydroxyapatite matrix were 10, 30, 50, 70 and 90 wt%. Consolidation of the composites was made by pressing ( P = 15 MPa) and sintering ( T = 1200 oC/1h). Dilatometer investigations of the composites show that composites with 10, 30 and 50 wt% are in thermal equilibrium. The increasement of SiO 2 content is reflected in decreasement of the density of the sintered composites. The E-modulus and shear modulus of the composites with 10, 30 and 50 wt% SiO 2 are 32 ± 1 GPa and 18 ± 3 GPa, respectively. The equations given by several authors like Turner, Kerner, Thomas, Tummala & Friedberg and Taya were used to predict the coefficient of thermal expansion of the composites as a function of E-modulus, shear modulus, module of compressibility, Poisson’s ratio and volume fraction of the constitutive phases. According to the coefficients of correlation, the equations given by Turner and Kerner give the best approximation of the experimental data.