Physico-chemical characterization of cement type hydration of alpha-tricalcium phosphate

Date

2024-12-02

Author

Köhnetarfun, Mehmet Yiğit

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Synthetic bone grafts are widely employed in bone restoration procedures, particularly in the treatment of bone defects. Alpha-tricalcium phosphate (α-TCP, α-Ca₃(PO₄)₂) is a commonly utilized calcium orthophosphate material for bone filling applications. Upon hydration with aqueous solutions, α-TCP-based powder cement systems undergo a transformation into calcium-deficient hydroxyapatite (CDHAp, Ca₉(HPO₄)(PO₄)₅(OH)), a key inorganic component of bone tissue that plays a critical role in bone healing and defect regeneration. The primary objective of this thesis is to synthesize pure α-TCP powder through a solid-state reaction, followed by detailed evaluation of its hydration behavior/reactivity under various reaction conditions. The investigation aims to identify the optimal parameters by assessing the transformation of the cement in terms of its microstructural and mechanical properties. The parameters including solid-to-liquid ratio of cement mixture, hydration temperature, hydration time, and hydration media were systematically studied. The experimental investigations were conducted using x-ray diffraction, electron microscopy, and mechanical testing to assess the effects of these variables. Specifically, the impact of temperature on hydration was examined at 25°C, 37°C, and 60°C. To explore the effect of the solid-to-liquid ratio, ratios of 1:1, 1:3, and 1:5 were tested. The effect of hydration time was evaluated at intervals of 1 hour, 4 hours, 8 hours, 12 hours, 24 hours, and 56 hours. Additionally, disodium phosphate (Na₂HPO₄) solutions were employed together with DI-water, to investigate the influence of the hydration media on cement conversion. The results demonstrated that the addition of Na₂HPO₄ significantly accelerated the α-TCP to CDHAp transformation; however, it concurrently led to a reduction in fracture strength.

Subject Keywords

Tricalcium phosphate, Bone fillers, Calcium deficiency hydroxyapatite

URI

https://hdl.handle.net/11511/112995

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Graduate School of Natural and Applied Sciences, Thesis