Sintering and mechanical properties of the alumina-tricalcium phosphate-titania composites

The objective of this study was to determine the effect of the content of titania and the sintering process on the transformation phase, the densification, the rupture strength and the microstructures of the alumina-10 wt.% tricalcium phosphate composites. After the sintering process, the samples were examined by using P-31 and Al-27 magic angle scanning nuclear magnetic resonance, X-ray powder diffraction and scanning electron microscopy analysis. The Brazilian test was used to measure the rupture strength of the samples. The present results provide new information about solid-state reactivity in the ternary system alpha-alumina-beta-tricalcium phosphate-anatase-titania. The differential thermal analysis of the alpha-alumina-beta-tricalcium phosphate-titania composites Shows two endothermic peaks, at 1360 degrees C and at 1405 degrees C, which are caused by the reactions between titania/alumina and titania/tricalcium phosphate, respectively. Thus, the presence of titania in the alumina-10 wt.% tricalcium phosphate leads to the formation of beta-Al2TiO5 at 1360 degrees C. At 1600 degrees C, the alumina-10 wt.% tricalcium phosphate-5 wt.% titania composites displayed the highest rupture strength (74 MPa), compared to the alumina-10 wt.% tricalcium phosphate composites (13.5 MPa). Accordingly, the increase of the rupture strength is due to the formation of the new beta-Al2TiO5 phase. (C) 2014 Elsevier B.V. All rights reserved.