Kinetics of conversion of brushite coatings to hydroxyapatite in alkaline solution

Daniel Navarro da Rocha, Marcelo H.Prado da Silva, José Brant de Campos, Rubens L.Santana Blazutti Marçal, Dindo Q. Mijares, Paulo Coelho, Leila Rosa Cruz

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Abstract

This work describes the kinetics of conversion of brushite coatings, produced by chemical deposition, to hydroxyapatite. The conversion was performed in alkaline solution at three temperatures: 50. °C, 55. °C, and 60. °C. The evolution of the transformation was assessed by X-ray diffraction, and the phase fractions were determined by Rietveld refinement. The Johnson-Mehl-Avrami equation was applied to the data in order to describe the conversion mechanisms. The value of 42. kJ/mol obtained for the conversion activation energy is of the same order as found in similar surface-controlled dissolution processes. The Avrami exponent was n = 3.5, which is consistent with an interface-controlled growth of three-dimensional HA crystals with decreasing nucleation rate.

Original languageEnglish (US)
JournalJournal of Materials Research and Technology
DOIs
StateAccepted/In press - Jan 1 2018

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Keywords

  • Activation energy
  • Avrami equation
  • Conversion kinetics
  • Hydroxyapatite

ASJC Scopus subject areas

  • Ceramics and Composites
  • Biomaterials
  • Surfaces, Coatings and Films
  • Metals and Alloys

Cite this

Rocha, D. N. D., Silva, M. H. P. D., Campos, J. B. D., Marçal, R. L. S. B., Mijares, D. Q., Coelho, P., & Cruz, L. R. (Accepted/In press). Kinetics of conversion of brushite coatings to hydroxyapatite in alkaline solution. Journal of Materials Research and Technology. https://doi.org/10.1016/j.jmrt.2018.02.002