Densification Behaviour and Mechanical Properties of Aluminium Oxide and Cerium Oxide-Doped Yttria Tetragonal Zirconia Polycrystal Ceramics Using Two-Step Sintering (original) (raw)
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Journal of the Australian Ceramic Society
The effect of additions of Al 2 O 3 and CeO 2 (up to 1 wt %) on the sintering behavior of yttria-stabilized Tetragonal Zirconia Polycrystals (Y-TZP) were studied. The effects of Al 2 O 3 and CeO 2 on the Vickers hardness, bulk density, fracture toughness and Young's modulus were carried out on the sintered samples. The sintering temperature was ranging from 1250 °C to 1450 °C with the ramp rate of 10°C/min. The results revealed that the doped samples demonstrated a stronger effect in contrast with the undoped samples. The relative densities were above 97.5 % of theoretical (i.e. > 6.1 gcm-3) could be obtained in Y-TZPs sintered at low temperatures, 1350 °C. The hardness's value of Y-TZP was increased in the 1 wt % Al 2 O 3 and CeO 2-doped samples when sintered above 1400 °C.
Hardness and Fracture Toughness of Alumina-Doped Tetragonal Zirconia with Different Yttria Contents
MATERIALS TRANSACTIONS, 2003
The 0.75 to 3.0 mol% Y 2 O 3-stabilized tetragonal ZrO 2 (Y-TZP) and Al 2 O 3 /Y-TZP fine-grained ceramics with 0.2 to 0.7 mass% of alumina were produced by a colloidal technique and low-temperature sintering. Trace alumina addition enhanced the densification of Y-TZP. The influence of the resulting density, microstructure, the yttria-stabilizer and the alumina content on the hardness and toughness were studied. The bulk 2.7Y-TZP ceramic with an average grain size of 110 nm reached a hardness of 13.6 GPa and fracture toughness of 11.2 MPaÁm 1=2. Y-TZP ceramics with a reduced yttria-stabilizer content were found to reach a fracture toughness of 13.8 MPaÁm 1=2 (2Y-TZP), and 14.5 MPaÁm 1=2 (1.5Y-TZP). A nano-grained alumina dispersed zirconia with 3 mol% Y 2 O 3 with an average grain size of 97 nm was obtained, and the hardness increased to 16.8 GPa. Y-TZP/alumina ceramics with a 0.35 mass% Al 2 O 3 were found to reach a fracture toughness of 15.7 MPaÁm 1=2 (2Y) and 15.3 MPaÁm 1=2 (1.5Y).
Preparation and Characterization of Yttria–Ceria Doped Tetragonal Zirconia / Alumina Composites
The International Conference on Applied Mechanics and Mechanical Engineering
Yttria-ceria doped tetragonal zirconia / alumina, (Y,Ce-TZP / Al 2 O 3) composites were prepared via sol-gel and powder mixing techniques. The bodies were uniaxially pressed at 220 MPa. The formed green bodies were fired at 1500˚C up to 1650˚C with temperature interval of 50˚C and firing rate of 5˚C /min. The samples were evaluated for their densification, microstructure and phase constitution as well as their mechanical properties. ANSYS (finite element package) is utilized to simulate the temperature distribution along the material and so thermal conductivity of the material is calculated. The present study results showed an improvement in the properties of the samples prepared via sol-gel route compared with traditional powder mixing one. X-ray diffraction patterns of both sol-gel and mechanically mixed fired samples indicate the presence of cerium-zirconium oxide (Ce 2 Zr 3 O 10) phase and the absence of cerium aluminate (CeAlO 3) phase. It was concluded that the starting materials preparation route has a noticeable impact on the sintering behavior and mechanical properties of the final product.
2017
In the current study, the effect of adding nano Al2O3 to 3 mol%Y2O3 stabilized tetragonal zirconia (3Y-TZP) prepared by precipitation method on the grain size and the mechanical properties was investigated. Different amount of nano Al2O3 (1.5 wt. % , 2.5 wt.% , 3.5 wt.% and 4.5 wt.%) have been added to (3Y-TZP). X-Ray diffraction (XRD) and scanning electron microscopy (SEM) was used to characterize both the prepared powder and the full dense ceramic composite. It has been found that ,the addition of nano Al2O3 have an influence on the densification process and lead to increase in both the apparent and bulk relative densities and recorded a 96.45% and 94.46 % respectively at 4.5 wt.%. The results also shows a decrease in grain size from 0.7 μm to 0.62 μm as the amount of nano Al2O3 vary from 0 wt.% to 4.5 wt.% due to the restricted of the grain boundary mobility via the effect of particle pinning. Also, the addition of nano Al2O3 have great effect on mechanical properties .The Vicker...
Sintering Behavior of 0.8 mol%-CuO-Doped 3Y-TZP Ceramics
Journal of the American Ceramic Society, 2006
In recent years, 3 mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) doped with copper oxide has obtained increasing interest due to its enhanced superplastisity and good potential in tribological applications. In this work, the effect of addition of small amounts (0.8 mol%) of copper oxide on the sintering behavior of 3Y-TZP was studied using a dilatometer and high-temperature X-ray diffraction (XRD). A qualitative sintering model was established based on several reactions during sintering as indicated by thermal analysis and XRD. Some of these reactions remarkably retard densification and consequently result in low final density (86%) of the sample sintered at 14001C in air. The reaction between molten Cu 2 O and yttria as segregated to the Y-TZP grain boundaries at around 11801C leads to the depletion of yttria from Y-TZP grains, which results in the formation of monoclinic phase during cooling. A relatively higher oxygen partial pressure can inhibit the dissociation of CuO to Cu 2 O. This inhibition in dissociation is one of the reasons why a dense (496%) 0.8 mol% CuO-doped 3Y-TZP ceramic can be obtained after sintering at 14001C in flowing oxygen.
2014
Background: The effect on mechanical properties and densification of Y-TZP ceramics doped with niobium pentoxide (Nb2 O5) (0.1 wt. % to 0.5 wt. %), has been investigated in this study. Samples were sintered at 1300-1500°C, retaining a holding time of 4 hours at 1200°C and then cooling back to room temperature. Vickers hardness, fracture toughness and bulk density test were analyzed on the sintered samples. From the result it was relevant that the two step sintering method was effective in promoting densification of the Nb2O5-doped Y-TZP without sacrificing tetragonal phase stability and mechanical properties. High densification, hardness occurred at 0.3 wt. %-0.5 wt. % ≥1400°C.
Sintering and Ageing Properties of Manganese Doped Y-TZP Ceramics
The sinterability of 3 mol% yttria-tetragonal zirconia polycrystals (Y-TZP) containing small amounts of manganese oxide (MnO2) as sintering aid was investigated over the temperature range of 1250°C to 1500°C. Sintered samples were evaluated to determine bulk density, Young’s modulus, Vickers hardness and fracture toughness. In addition, the tetragonal phase stability of selected samples was evaluated by subjecting the samples to hydrothermal ageing in superheated steam at 180°C/10 bar for periods up to 525 hours. The research showed that the addition of MnO2, particularly ³ 0.3 wt%, was effective in aiding densification and improving the matrix stiffness and hardness when compared to the undoped Y-TZP sintered at temperatures below 1350°C. On the other hand, the fracture toughness of Y-TZP was unaffected by MnO2 addition except for the 1 wt% MnO2-doped Y-TZP samples sintered above 1400°C. The hydrothermal ageing resistance of Y-TZP was significantly improved with the additions of Mn...
Low-Temperature Processing and Mechanical Properties of Zirconia and Zirconia-Alumina Nanoceramics
Journal of the American Ceramic Society, 2003
The 1.5-to 3-mol%-Y 2 O 3 -stabilized tetragonal ZrO 2 (Y-TZP) and Al 2 O 3 /Y-TZP nanocomposite ceramics with 1 to 5 wt% of alumina were produced by a colloidal technique and lowtemperature sintering. The influence of the ceramic processing conditions, resulting density, microstructure, and the alumina content on the hardness and toughness were determined. The densification of the zirconia (Y-TZP) ceramic at low temperatures was possible only when a highly uniform packing of the nanoaggregates was achieved in the green compacts. The bulk nanostructured 3-mol%-yttria-stabilized zirconia ceramic with an average grain size of 112 nm was shown to reach a hardness of 12.2 GPa and a fracture toughness of 9.3 MPa⅐m 1/2 . The addition of alumina allowed the sintering process to be intensified. A nanograined bulk alumina/zirconia composite ceramic with an average grain size of 94 nm was obtained, and the hardness increased to 16.2 GPa. Nanograined tetragonal zirconia ceramics with a reduced yttria-stabilizer content were shown to reach fracture toughnesses between 12.6 -14.8 MPa⅐m 1/2 (2Y-TZP) and 11.9 -13.9 MPa⅐m 1/2 (1.5Y-TZP).
Journal of Materials Engineering and Performance, 2014
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Your article is protected by copyright and all rights are held exclusively by ASM International. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to selfarchive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".