ISSN:
1662-100X
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Biology
,
Technology
Notes:
Hydroxyapatite-zirconia composites have received much attention during the last decadedue to their combination of the desirable mechanical properties of zirconia and the excellentbioactivity of hydroxyapatite (HA). However, thermal decomposition of the hydroxyapatite phase andreaction between the zirconia phase and the hydroxyapatite phase remain a major problem in thehydroxyapatite-zirconia composites. In this study, thermally stable and fluorine-substitutedhydroxyapatite (Ca10(PO4)6(OH)0.8F1.2; coded as HA06F) was prepared by a sol-gel method to replacethe hydroxyapatite. Yttria-stabilized zirconia (YTZP) was also prepared by a sol-gel method in orderto produce HA06F-YTZP composites with 5, 10, 15, 20, 40, and 60 wt% YTZP by simple andcost-effective pressureless sintering. Thermogravimetric analysis (TGA) and x-ray diffraction (XRD)of the HA06F-YTZP composites showed that the thermal stability of the HA06F matrices could bemaintained when the YTZP content did not exceed 20 wt% and for sintering temperatures less than1400 oC. Dilatometric analysis and microstructural observation revealed that the YTZP phase in theHA06F-YTZP composites retarded the densification of the composites if the zirconia content wasover 20 wt%. Electron scanning microscopy (SEM) and high resolution transmission electronmicroscopy (HR-TEM) of the HA06F-YTZP composites showed that the YTZP second phase had asize in the nanometer scale and the reaction between the HA06F phase and the zirconia phase wassuppressed. Mechanical properties including the Knoop hardness, the Young’s modulus, and thefracture toughness of the HA06F-YTZP composites increased with the YTZP content until theoptimal content of 20 wt%; higher YTZP contents led to low mechanical properties due to poordensification of the composites and the severe thermal decomposition of the HA06F phase. Theoptimal HA06F-20YTZP composite also showed desirable attachment and proliferation of osteoblastcells. Nevertheless, the study of the composite system indicated the limitations of the pressurelesssintering technique. To achieve the full potential of the composites for medium or low load bearingapplications, a pressure-assisted sintering technique would still be necessary
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/43/transtech_doi~10.4028%252Fwww.scientific.net%252FJBBTE.1.57.pdf
