Fabrication, structure, mechanical and thermal properties of zirconia-based ceramic nanocomposites

The paper addresses the new nanocomposite prepared by pressureless sintering method (PSM). The properties of the yttrium stabilized zirconia (Y-TZP)/zircon (ZrSiO₄) composite obtained by PSM are discussed in terms of its structure and fabrication conditions that include the content of cordierite in the initial mixture of cordierite and Y-TZP nanopowders and sintering temperature. The structural information has been obtained by X-ray diffraction (XRD), high-resolution scanning and transmission microscopy, density measurements, as well as differential thermal analysis (DTA) and thermogravimetry (TG), while mechanical examinations included both measurements of fracture toughness and flexural strength. The obtained results point towards possibility of control the amount of tetragonal zirconia with nano-size grains in a final composite, by a selection of the proper sintering temperature. The interesting finding of this study concerns the coefficient of thermal conductivity of Y-TZP-based composites with zircon, fabricated from the powder with more than 15 vol.% content of cordierite, which appears to be lower than that of pure zirconia, despite the mixed materials exhibit high thermal conductivity. The DTA-TG examination confirmed excellent stability of the composite at the elevated temperatures and proved the lack of the nanocomposite oxidation.