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Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/41670
- Thermal analysis of amorphous phases in hydroxyapatite coatings
- Gross, Karlis A.; Gross, Volfgangs; Berndt, C. C.
- The amorphous phase in hydroxyapatite coatings has been examined by using X-ray diffractometry, Fourier transform infrared spectroscopy, optical microscopy, and thermal analysis methods. The amorphous phase mostly consists of a dehydroxylated calcium phosphate. When heated, crystallization of hydroxyl-rich areas produces hydroxyapatite, followed by diffusion of hydroxyl ions, thus increasing the amount of crystalline phase. Hydroxyl-deficient amorphous areas crystallize to oxyapatite at 700°C. Thus, crystallization occurs over a range of temperatures and is dependent on the hydroxyl content of the amorphous phase and the partial water-vapor pressure. The activation energies of crystallization to hydroxyapatite, diffusion of hydroxyl ions, and crystallization to oxyapatite are 274, 230, and 440 kj/mol, respectively. Shrinkage from these processes leads to a crack network and decreases the mechanical strength of the coating.
- Publication type
- Journal article
- Journal of the American Ceramic Society, Vol. 81, no. 1 (Jan 1998), pp. 106-112
- Publication year
- Activation energy; Amorphous phase; Ceramic coatings; Composition effects; Crystalline phase; Crystallization; Dehydroxylated calcium phosphate; Diffusion; Fourier transform infrared spectroscopy; Heating; Hydroxyapatite coatings; Ions; Optical microscopy; Partial water vapor pressure; Shrinkage; Strength of materials; Thermoanalysis; X-ray diffraction analysis
- Wiley-Blackwell Publishing
- Publisher URL
- Peer reviewed