Controlled microstructural evolution of Hydroxyapatite-Bioglass® nanocomposites via two-step sintering

Area of Science:

• Biomaterials Science
• Materials Engineering
• Nanotechnology

Background:

• Hydroxyapatite (HA) and Bioglass® (45S) are key biomaterials for bone regeneration.
• Optimizing processing methods is crucial for enhancing their performance in implants.
• Two-step sintering (TSS) offers potential for improved densification and phase stability.

Purpose of the Study:

• To fabricate and optimize Hydroxyapatite-Bioglass® nanocomposites using two-step sintering (TSS).
• To investigate the effect of TSS parameters on densification, phase stability, and mechanical properties.
• To evaluate the potential of these nanocomposites for bone regeneration applications.

Main Methods:

• Composite nanopowders prepared via sol-gel route.
• Pellets compacted and subjected to a two-step sintering (TSS) protocol with varied temperatures and holding times.
• Characterization using X-ray diffraction, scanning electron microscopy, bulk density, and nanoindentation.

Main Results:

• Optimized TSS parameters (1150°C for 15 min, then 1050°C for 25 h) achieved best densification and phase stability.
• Bioglass® addition promoted densification and increased β-tricalcium phosphate (β-TCP) formation.
• 10 wt% Bioglass® composite showed highest density and superior mechanical properties (hardness, modulus, toughness) with nanoscale grains.
• Enhanced fracture toughness observed due to crack-bridging and transformation toughening.

Conclusions:

• Controlled two-step sintering (TSS) effectively tailors the microstructure and performance of HA-Bioglass® nanocomposites.
• The optimized nanocomposites exhibit excellent densification and mechanical properties.
• These findings present a promising strategy for developing advanced bioceramic implants for bone regeneration.