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ABSTRACT
Calcium Phosphate glass-ceramic have a potential in application of biomaterials, due to their composition was as like human’s, nontoxic and bio-compatible. In our study, in order to improve the crystallizability of glass-ceramic addition of the nucleus agents to calcium phosphate glass was performed. It is excepted to increase mechanical properties.
Application of calcium phosphate glass was limited, because of their higher melting point and absorption. Generally, matrix glass with Ca/P molar ratios lower than 0.7 was comfortable. In this work, six kinds of matrix glass were selected with molar ratios ranging from 0.3 to 0.6. By addition of calcium pyrophosphate and calcium metaphosphate, the detail reaction mechanism in solid state will be gotten. Using DTA, XRD and SEM, the effects of addition of nucleus agent were investigated.
Adding calcium pyrophosphate to matrix glass with higher molar ratios, the forming temperature of bata-calcium metaphosphate nuclide decreased with additions. However, the crystal growth did not concern with nucleus agent directly. After addition, crystallization reaction was fast more than non-addition. In additional, the crystal phase own thermal stableness well. According to the result of thermal analysis, adding procedure make exothermic peak of the crystal growth symmetric. Further, in the investigation on thermodynamic, the lower value of growth activity energy, Ea=243.75 KJ/mole, was gotten. The crystal morphology was small and distributed well in bulk of glass.
Adding calcium metaphosphate to matrix glass with lower molar ratios, the forming temperature of bata-calcium metaphosphate nuclide also was decreased and the crystallization raising, but have lower reaction rate. The crystal morphology was network differ to higher molar ratio glass and non-additional glass. Unexpectedly, a mirror product, Ca2P6O17 poor crystal, was find besides the major phase β-Ca(PO3) 2 by XRD studying.
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