Sintering behaviour of 45S5 bioactive glass

Area of Science:

• Materials Science
• Ceramics Engineering
• Biomaterials Science

Background:

• Bioglass sintering is crucial for fabricating ceramic components.
• Understanding structural transformations is essential for controlling sintering kinetics.

Purpose of the Study:

• To investigate the effect of Bioglass structural transformations on its sintering behavior.
• To correlate specific transformations with changes in sintering rate and shrinkage.

Main Methods:

• Thermal analysis (Differential Scanning Calorimetry, Thermogravimetric Analysis) to identify transformations.
• Dilatometry to measure sintering shrinkage.
• Modification of Frenkel's model to analyze phase separation kinetics.

Main Results:

• Five successive transformations observed up to 1000°C: glass transition, phase separation, two crystallizations, and a second glass transition.
• Two main sintering shrinkage stages identified, linked to glass transitions at 550°C and 850°C.
• Glass-in-glass phase separation at 580°C initially decreased sintering rate, followed by crystallization (Na2CaSi2O6) and sintering inhibition.

Conclusions:

• Bioglass structural transformations, particularly glass-in-glass phase separation and crystallization, critically influence sintering.
• The modified Frenkel model successfully quantifies phase separation kinetics and links structural changes to sintering behavior.
• Controlling these transformations offers a pathway to tailor Bioglass sintering for specific applications.