Alumina and fluorapatite powder were mixed in a wet medium in order to elaborate biphasic ceramics composites. The effect of fluorapatite addition (26.5 wt%) in the densification and the mechanical properties of the a...Alumina and fluorapatite powder were mixed in a wet medium in order to elaborate biphasic ceramics composites. The effect of fluorapatite addition (26.5 wt%) in the densification and the mechanical properties of the alumina matrix were measured. The phase developments have been systematically analysed by scanning electronic microscopy, X-ray diffraction, Infrared spectroscopy and 31P and 27Al magic angle scanning nuclear magnetic resonance. The Brazilian test was used to measure the mechanical resistance of alumina - 26.5 wt% fluorapatite composites. The densification and strength rupture of composites increase versus sintering temperature and holding time. At 1600°C, the composites densities reached 85% and the rupture strength was about 22 MPa. Also, the composites sintering at 1500°C for 5 hours provides samples with similar density and having higher mechanical resistance, above 26 MPa. For longer holding times, the mechanical properties were hindered by the exaggerated grain growth and the formation of intragranular porosity. From 1400°C, the characterization of the alumina - 26.5 wt% fluorapatite composites indicates the formation of calcium aluminates.展开更多
Mechanical properties of alumina-fluorapatite composites with different titania additive amounts （0, 0.5, 1, 1.4, 2, 3, 4 and 5 wt%） have been investigated between 1200 and 1600℃. The optimum values of densificatio...Mechanical properties of alumina-fluorapatite composites with different titania additive amounts （0, 0.5, 1, 1.4, 2, 3, 4 and 5 wt%） have been investigated between 1200 and 1600℃. The optimum values of densification and mechanical properties of composites have been reached with 1.4 wt% of titania after the sintering process at 1500℃ for 1 h. Thus, the rupture strength of alumina-26.52 wt% Fap-1.4 wt% TiO2 reaches 75 MPa. At higher temperature and beyond 1.4 wt% TiO2 ,the densification and mechanical properties were hindered by the formation of both intergranular porosity and secondary phase. X-ray diffraction （XRD） analysis of alumina-Fap-TiO2 composites shows the formation of aluminium titanate （Al2O3-TiO2：Al2TiO5 ）. The 27Al magic angle scanning nuclear magnetic resonance analysis of Al2O3-Fap-TiO2 composites reveals the presence of octahedral and pentahedral aluminium and novel environment relative to tetrahedral aluminium sites.展开更多
文摘Alumina and fluorapatite powder were mixed in a wet medium in order to elaborate biphasic ceramics composites. The effect of fluorapatite addition (26.5 wt%) in the densification and the mechanical properties of the alumina matrix were measured. The phase developments have been systematically analysed by scanning electronic microscopy, X-ray diffraction, Infrared spectroscopy and 31P and 27Al magic angle scanning nuclear magnetic resonance. The Brazilian test was used to measure the mechanical resistance of alumina - 26.5 wt% fluorapatite composites. The densification and strength rupture of composites increase versus sintering temperature and holding time. At 1600°C, the composites densities reached 85% and the rupture strength was about 22 MPa. Also, the composites sintering at 1500°C for 5 hours provides samples with similar density and having higher mechanical resistance, above 26 MPa. For longer holding times, the mechanical properties were hindered by the exaggerated grain growth and the formation of intragranular porosity. From 1400°C, the characterization of the alumina - 26.5 wt% fluorapatite composites indicates the formation of calcium aluminates.
文摘Mechanical properties of alumina-fluorapatite composites with different titania additive amounts （0, 0.5, 1, 1.4, 2, 3, 4 and 5 wt%） have been investigated between 1200 and 1600℃. The optimum values of densification and mechanical properties of composites have been reached with 1.4 wt% of titania after the sintering process at 1500℃ for 1 h. Thus, the rupture strength of alumina-26.52 wt% Fap-1.4 wt% TiO2 reaches 75 MPa. At higher temperature and beyond 1.4 wt% TiO2 ,the densification and mechanical properties were hindered by the formation of both intergranular porosity and secondary phase. X-ray diffraction （XRD） analysis of alumina-Fap-TiO2 composites shows the formation of aluminium titanate （Al2O3-TiO2：Al2TiO5 ）. The 27Al magic angle scanning nuclear magnetic resonance analysis of Al2O3-Fap-TiO2 composites reveals the presence of octahedral and pentahedral aluminium and novel environment relative to tetrahedral aluminium sites.
