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Development and characterization of alumina-toughened zirconia (ATZ) ceramic composites doped with a beneficiated rare-earth oxide extracted from natural ore

2021; Elsevier BV; Volume: 16; Linguagem: Inglês

10.1016/j.jmrt.2021.11.141

2214-0697

Eduardo de Sousa Lima, Camila Catalano Gall, Manuel Fellipe Rodrigues Pais Alves, José Brant de Campos, Tiago Moreira Bastos Campos, Claudinei dos Santos,

Nuclear materials and radiation effects

This work analysed the effect of the addition of rare-earth mixed oxide (RE2O3), a solid solution of Y2O3 and other rare earths benefited from a Brazilian natural ore called Xenotime, on the sintering and properties of a commercial nanopowder composed of Ce-tetragonal polycrystal zirconia (TZP) + 15 wt.% Al2O3. Powder mixtures were prepared, adding 10 wt.% of Y2O3 or 10 wt.% RE2O3 in Ce-TZP/Al2O3 powder, which were compacted and sintered at 1500 °C for 2 h. Sintered samples were characterized by X-ray diffraction, scanning electron microscopy, and relative density. Structural analyses and phase quantification were performed using the Rietveld refinement method. Mechanical characterization - Vickers hardness and fracture toughness - of the samples was carried out by Vickers indentation. The results indicated that the RE2O3 is composed of a solid Y2O3 solution with lattice parameters slightly lower than those of pure Y2O3 due to the presence of other oxides such as Yb2O3 (19.7%), Er2O3 (13.9%), or Dy2O3 (10.2%). During sintering, the oxides added to the composite were completely consumed by the Ce-TZP/Al2O3 matrix to form two different crystalline phases: ZrO2-Cubic and Y3Al5O12. As a consequence, multi-phase composites with relative density of 93.8 ± 1.2 (Y2O3 reinforced) and 94.5 ± 1.7 (RE2O3 reinforced), average hardness in the order of 10.5 GPa, and fracture toughness of 7.1–8.5 MPa m1/2 were obtained. The high fracture toughness observed was a consequence of the presence of different coupled toughening mechanisms resulting from the multiphase characteristic of these composites.