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Lecture

Effect of the cooling rate on physicochemical properties of tricalcium phosphate and derived calcium phosphate cement

Thursday (27.09.2018)
11:45 - 12:00 S1/03 - 23
Part of:


Bone implants is a broad and of current interest topic for research and developments and new contributions are presented day by day trying to fill the needs of orthopedic challenges. Among these materials calcium phosphate cements (CPC) present different behaviors as biocompatibility, biodegradability and bioactivity, besides other interesting characteristics as fast preparation, easy molding and setting at corporal temperature. Despite the fact that several formulations of CPC are known, obtaining it from alpha tricalcium phosphate (α-TCP) by mixing with deionized water is of great interest as it leads to the formation of a calcium deficient Hydroxyapatite (CDHA) which is of big importance to maintain the biodegradable behavior of the cement. TCP presents three polymorphs at high temperatures (β, α and α´) and it is frequent to detect the presence of the β phase as an impurity, which normally is attributed to a non-enough fast cooling in the TCP synthesis. In this work we analyze the differences among three cooling methods in the preparation of TCP (inside the furnace at 10ºC/min, quenched with air jet and quenched with air jet assisted by strikes to enhance the cooling surface area) by evaluating its physicochemical properties by thermogravimetric/differential thermal analysis (TGA/DTA), X ray fluorescence (XRF), X ray diffraction (XRD), and Fourier transform infrared (FTIR). Furthermore, the CPC obtained using the three TCP powders was evaluated by scanning electron microscopy (SEM), XRD, FTIR and mechanical compression. Results show that no major impurities of β phase is presented on the powders even by cooling it at a low rate as 10ºC/min. Moreover, CPCs presented similar physicochemical characteristics and mechanical behavior. This work helps in the understanding of the allotropic phase transformation of β↔α TCP as higher energy is required to transform from β to α than in its opposite way and that a low cooling rate (10ºC/min) is enough to obtain a TCP that leads to a CPC with an acicular open flower CDHA structure as it is seen on SEM.

Speaker:
Dipl.-Ing. Daniel Moreno Duarte
University of Antioquia
Additional Authors:
  • Prof. Dr. María Esperanza López Gómez
    University of Antioquia
  • Dr. Fabio Vargas Galvis
    University of Antioquia

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