Hydroxyapatite–Magnesium Bioceramics: Synthesis and Mechanical–Chemical Characterization

Hydroxyapatite (HA) is widely used in biomedical applications due to its biocompatibility and chemical similarity to the mineral phase of bone; however, its low mechanical strength limits its structural use. In this work, HA ceramics with different Mg additions (0, 0.5, 1, 3, 5, and 10% by weight) were prepared using the powder processing technique. The mixtures were homogenized, conformed and sintered at 1100°C. The incorporation of Mg produced a general increase in mechanical properties compared to pure HA. The best mechanical performance was obtained with the formulation containing 5% Mg by weight, achieving a hardness of 319 HV, a porosity of 12.92% and a fracture toughness of 4.06 MPa·m0.5, comparable to those reported for human cortical bone, indicating its potential for applications in moderately loaded bone implants. These results suggest that Mg acts as a reinforcing agent in the ceramic matrix, reducing critical defects, which translates into increased mechanical strength. The polarization resistance results show that the incorporation of low fractions by weight of magnesium (1% Mg) optimizes the electrochemical behavior of the material, while higher increases in its concentration cause a slight deterioration of this property.