Effect of Microsilica on Natural Hydroxyapatite in the Synthesis of Calcium Phosphate/Calcium Silicate Bioceramics: Characterization and Evaluation of Their Mechanical and Surface Properties

In this study, bioceramic composites based on natural hydroxyapatite and microsilica at 0, 3, 6, and 9% by weight were prepared. Powder mixing was performed using a high-energy ball mill, and the samples were heat-treated at 1200 °C for 2 hours. Phase identification was performed by X-ray diffraction (XRD), which confirmed the presence of hydroxyapatite, calcium silicate hydrate, and calcium silicate. The synthesized powders were compacted under a pressure of 50 MPa into cylindrical and disk-shaped specimens with a diameter of 10 mm, and their mechanical and surface properties—including compressive strength, density, porosity, surface roughness, and wettability—were evaluated. The results indicated that the sample containing 6 wt% microsilica (HM6) exhibited the highest compressive strength and density, along with the lowest apparent porosity and surface roughness. Therefore, the addition of 6 wt% microsilica leads to the formation of calcium phosphate–calcium silicate bioceramics with improved mechanical and surface properties, and the HM6 composition is proposed as the optimal candidate for bone tissue engineering applications.