Open AccessKinetics of conversion of brushite coatings to hydroxyapatite in alkaline solution
Author(s) -
Daniel Navarro da Rocha,
Marcelo Henrique Prado da Silva,
José Brant de Campos,
Rubens Lincoln Santana Blazutti Marçal,
Dindo Q. Mijares,
Paulo G. Coelho,
L. R. Cruz
Publication year - 2018
Publication title -
journal of materials research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.832
H-Index - 44
eISSN - 2214-0697
pISSN - 2238-7854
DOI - 10.1016/j.jmrt.2018.02.002
Subject(s) - brushite , materials science , nucleation , kinetics , activation energy , dissolution , rietveld refinement , avrami equation , chemical engineering , phase (matter) , deposition (geology) , mineralogy , thermodynamics , crystallography , chemistry , crystal structure , arrhenius equation , metallurgy , calcium , paleontology , physics , organic chemistry , quantum mechanics , sediment , biology , engineering
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.
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