Papers by Keyword: ZrO₂-Al₂O₃

Abstract: In order to develop porous ceramics with high strength and corrosion resistance as the support for the preparation of asymmetric ceramic membranes, porous ZrO₂-Al₂O₃ composite is designed and fabricated by adding Zr(OH)₄.as sintering aid. The content of Zr(OH)₄, the sintering temperature and the bending strength before and after corrosion of the composite are discussed. The results shows that 10wt% ZrO₂-10wt% Zr(OH)₄ -80wt%Al₂O₃ composite bar fabricated by cold press with the porosity of 32% can be fabricated in 1550°C for 4 h. The bending strength of the composite is 111.2MPa. After corrosion, the quality lose and the bending strength lose is no more than 1%. The tubular composite is suit for the preparation of micro-filtration membrane.

Abstract: Yttria-doped zirconia nanopowders have been obtained using the hydrothermal procedure starting from soluble inorganic salts. The mechanisms and kinetics of the process have been studied to obtain high purity powders with a crystalline size range of 4 to 22nm and specific surface near 200 m2/g. These powders have been have been used to obtain membranes with controlled thickness and with densities over 95% of the theoretical value by employing the tape casting technique using organic binders, dispersants and surfactants. The influence of the additives and sintering regime on the density and microstructure of membranes has been studied. The ionic conductivity of the materials was investigated and modelled. Different types of ruthenate pastes were used to obtain thick resistive films on the zirconia membranes and interactions between the substrate and membranes were studied. Finally the gauge characteristics of the device and possibilities for applications as mechanical pressure sensors with high sensitivity are discussed.

Abstract: ZrO₂/Al₂O₃ bilayer structure was investigated as one of potential replacements for SiO₂ gate dielectric. Al₂O₃ and ZrO₂ films were also examined and showed stoichiometric characteristics with negligible chlorine and carbon impurities. Al₂O₃ film exhibited an amorphous structure without interlayer formation while ZrO₂ film showed a randomly oriented polycrystalline structure with amorphous phase of interlayer. ZrO₂/Al₂O₃bilayer film exhibited no interfacial layer between Si substrate and Al₂O₃ layers. The flat band voltage and hysteresis of ZrO₂/Al₂O₃bilayer film were 0.8 V and 150 mV, respectively, with fully reversible hysteresis. The measured leakage current of ZrO₂/Al₂O₃bilayer film was 1.2E-6 A/cm2 with EOT value of 1.4 nm. ZrO2/Al2O3 bilayer film showed significantly enhanced gate oxide properties compared to those of the individual Al₂O₃ and ZrO₂ films.