Papers by Keyword: Substituted Hydroxyapatite

Abstract: The present work is aimed at the synthesis of fluorine substituted and carbonate substituted hydroxyapatites (FHA, CHA) by the mechanochemical method. The shortest milling time required for the synthesis of FHA and CHA using calcium hydroxide and diammonium hydrogen phosphate as precursors was estimated. In addition to the Ca and P precursors, ammonium carbonate and ammonium fluoride were used for carbonate and fluorine substitutions, respectively. Thermal stability of the synthesized FHA and CHA was evaluated. The phase composition and crystallite size were evaluated by the X-Ray Diffraction (XRD). Fourier Transform Infrared Spectroscopy (FTIR) technique was employed to confirm the functional groups corresponding to the FHA and CHA. Thermal stability of the FHA and CHA was determined by the XRD and FTIR studies on the FHA and CHA powders annealed at 900 ^°C. From the XRD and FTIR results, it is observed that the 30 min milling time is the shortest time for the complete formation of FHA and CHA. The powders synthesized with a minimum milling time of 30 min exhibited better thermal stability.

Abstract: Investigations of wollastonite and calcium phosphate biocoatings with Zn-and Cu-incorporation produced by a microarc oxidation method were presented. Dependences of coating properties on the microarc oxidation parameters were revealed. A variation of the process parameters allowed us to produce wollastonite-calcium phosphate coatings with a plate-like structure, thickness of 25–30 μm, roughness of 2.5–5.0 μm, and enhanced strength properties. Coatings based on substituted hydroxyapatite deposited under voltages of 200–250 V have an X-ray amorphous structure. An increase of oxidation voltage to 300 V leads to the formation of crystalline phases in the coating, such as CaHPO₄ and β-Ca₂P₂O₇. The maximum content of 0.4 at% zinc and 0.1 at% copper was obtained for coatings based on Zn-and Cu-substituted hydroxyapatites, consequently, deposited under oxidation voltage of 250 V.