Investigation of strengthened hydroxyapatite/ß-tricalcium phosphate composites with tailored porosity
Final Report Abstract
Calcium phosphate scaffolds have been used in clinical applications as a bone graft material for many years. Vapor transport sintering (VTS) in halide atmospheres is a novel method for the cost-efficient production of calcium phosphate ceramic scaffolds. During sintering, the presence of a reactive halide atmosphere enhances evaporation and condensation of solid calcium phosphate resulting in the simultaneous coarsening of pores and grains for all tested additives, i.e. HCl, HBr, CaCl2, MgCl2 and AgCl. The VTS method provides a ceramic scaffold structure with fully interconnected porosity. As the shrinkage rate resulting from VTS is generally very low compared to sintering in air, this method holds potential for the nearnet-shape manufacturing of the green body for the fabrication of custom-made ceramics. However, due to the rather low sinterability of β-TCP, the effect of VTS on the microstructure will be less pronounced for this precursor material. As the phase conversion of β-TCP to apatite can be influenced by limiting the Cl-availability, β-TCP and biphasic calcium phosphate (BCP) are both suitable starting materials for the fabrication of biphasic ceramics of adjustable phase composition. For bone graft applications, VTS needs to be combined with other processing techniques to meet the requirements regarding pore volume and size. Notwithstanding this limitation, the fine dispersion of Ag particles resulting from the presence of AgCl in the sintering atmosphere is promising with regard to the potential reduction of infection risks. To conclude, the VTS method offers high versatility for the fabrication of custom-made calcium phosphate ceramic scaffolds which can be adjusted to various requirements.
Publications
- 2012. Vapor transport sintering of calcium phosphate ceramics. Dissertation, Technische Universität Darmstadt, Darmstadt, Germany
Schlosser, M.
- 2012. Vapor transport sintering of porous calcium phosphate ceramics. Journal of the American Ceramic Society, 95 (5), 1581-1587
Schlosser, M., Kleebe, H.-J.
(See online at https://doi.org/10.1111/j.1551-2916.2012.05121.x) - 2013. Combined hydrothermal conversion and vapor transport sintering of Agmodified calcium phosphate scaffolds. Journal of the American Ceramic Society, 96 (2), 412-419
Schlosser, M., Fröls, S., Hauf, U., Sethmann, I., Schultheiss, S., Pfeifer, F., Kleebe, H.- J.
(See online at https://doi.org/10.1111/jace.12137) - 2013. Pseudomorphic transformation of Ca/Mg carbonates into phosphates with focus on dolomite conversion. Mineralogical Magazine, 77 (6), 2725-2737
Schultheiss, S., Sethmann, I., Schlosser, M., Kleebe, H.-J.
(See online at https://doi.org/10.1180/minmag.2013.077.6.03)
