Liquid-phase-assisted sintering of β-TCP using borate bioactive glass as a sintering aid

13-93B3 borate bioactive glass was investigated as a potential liquid-phase sintering aid for β-tricalcium phosphate (β-TCP) ceramics. Composites containing 5–15 wt% glass were pressurelessly sintered in air, and thermomechanical analysis revealed a two-stage shrinkage behavior with onset between 780 and 840 °C and rapid densification between 880 and 950 °C, suggesting viscous-flow-assisted behavior during sintering. X-ray diffraction identified the formation of calcium borate, borophosphate, and sodium phosphate phases, demonstrating chemical interactions between the glass and β-TCP. Archimedes measurements confirmed enhanced densification of all glass-containing compositions compared with pure β-TCP, while scanning electron microscopy revealed microstructural changes consistent with viscous-flow-assisted behavior. These results support the potential of borate bioactive glass as a sintering aid for β-TCP, suggesting liquid-phase-assisted behavior and offering a promising route for processing bioactive β-TCP composites.