Densification Studies of Tetragonal Zirconia with Manganese as Sintering Additive (original) (raw)
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Influence of manganese on the sintering properties of tetragonal zirconia
Ceramics - Silikaty, 2013
The influence of small additions of MnO2 (up to 1 wt. %) on the sintering behaviour of yttria-stabilized zirconia sintered over the temperature range from 1250°C to 1500°C was investigated. It was found that the mechanical properties of Y-TZP were dependent on the dopant amount and sintering temperature. The results revealed that relative densities above 97.5 % of theoretical (i.e. < 5.95 Mg m-3) could be obtained in Y-TZPs sintered at low temperatures, 1250°C and 1300°C, with the additions of ≥ 0.3 wt. % MnO2. In comparison to the undoped samples, the additions of up to 1 wt. % MnO2 and for sintering up to 1350°C was found to be beneficial in enhancing the Vickers hardness of the ceramic. The fracture toughness of Y-TZP however, was found to increase only in the 1 wt. % MnO 2-doped samples when sintered above 1400°C. The relation between the measured mechanical properties is discussed with the emphasis on the role of the manganese oxide. www.doaj.org/doaj?func=fulltext&aId=1470542
Science of Sintering, 2016
In the current paper we present a study of the sinterability of two zirconia (ZrO2) nanopowders with different content of yttrium oxide (Y2O3) 3 and 8 % tetragonal and cubic zirconia, respectively. After sintering between 900-1500?C, the samples were characterized in terms of their density and porosity using Archimedes technique. Their grain size was evaluated using scanning electron microscope (SEM). Vickers hardness and fracture toughness (KIC) were measured by the indentation method. The results showed that pores are almost eliminated at sintering temperatures higher than 1400?C and grain size is larger due to the agglomerates formed as a result of grain growth. Vickers hardness evaluated at 1400?C sintering temperature is greater than that obtained at 1500?C due to the grain growth produced at this temperature. In addition, we show a correlation between Vickers hardness and the porosity, obtained by evaluating empirical and theoretical models.
Densification and properties of zirconia prepared by three different sintering techniques
Ceramics International, 2007
Densification of nanocrystalline yttria stabilized zirconia (YSZ) powder with 8 mol% Y 2 O 3 , prepared by a glycine/nitrate smoldering combustion method, was investigated by spark plasma sintering, hot pressing and conventional sintering. The spark plasma sintering technique was shown to be superior to the other methods giving dense materials (!96%) with uniform morphology at lower temperatures and shorter sintering time. The grain size of the materials was 0.21, 0.37 and 12 mm after spark plasma sintering, hot pressing and conventional sintering, respectively. Total electrical conductivity of the materials showed no clear correlation with the grain size, but the activation energy for spark plasma sintered materials was slightly higher than for materials prepared by the two other densification methods. The hardness, measured by the Vickers indentation method, was found to be independent on grain size while fracture toughness, derived by the indentation method, was slightly decreasing with increasing grain size. #
Sintering properties of zirconia-based ceramic composite
Materials Research Innovations, 2014
This study examines the effects of different ZrB 2 content on various mechanical properties and electrical conductivity of ZrB 2 /Y-TZP composite. Composites with ZrB 2 content of up to 20 wt-% were particularly beneficial at the lower sintering temperature range by achieving greater densification and better hardness than Y-TZP monolith. In contrast to the trends estimated from rule of mixture, the increment of ZrB 2 content did not result in any significant improvement in the elastic modulus and hardness of the zirconia composites. Nevertheless, all composites showed tremendous improvement in fracture toughness compared with monolithic Y-TZP and thus, suggested that other toughening mechanisms were operative besides transformation toughening of zirconia. Incorporation of ZrB 2 up to mass fraction of 20 wt-% into Y-TZP generally did not affect the tetragonal phase stability of zirconia. Significant reduction of electrical resistivity of the composites was achieved with ZrB 2 content of 20 wt-% and sintering temperature of 1400°C.
Effect of sintering additives on the properties of alumina toughened zirconia (ATZ)
MRS Communications
The effect of small amounts of copper oxide, manganese oxide, and stainless steel as sintering additives on the sintering behavior and mechanical properties of Alumina Toughened Zirconia (ATZ, 3Y-TZP with 20 wt% Al2O3) ceramic composites were evaluated and contrasted with that of undoped ATZ by using microwave sintering (MW) method. Green bodies were sintered at 1250°C, 1350°C, and 1500°C using a holding time of 5 min., with a heating rate of 30°C /min. In general, all ATZ samples exhibited a similar trend, as the results showed that the relative density and mechanical properties increased with increasing sintering temperature regardless of the addition of dopants. It was found that the addition of 0.2 wt% CuO, 0.5 wt% MnO2, and 0.2 wt% SS were beneficial in enhancing the densification and improving the mechanical properties of ATZ without inducing grain coarsening. The ATZ composite samples' relative density, tetragonal phase stability, microstructural evolution, Vickers hardne...
Influence of sintering profile on the mechanical properties of manganese oxide doped 3Y-TZP
IOP Conference Series: Earth and Environmental Science, 2020
Zirconia ceramic has been identified as one of the advanced ceramic material with great mechanical properties which is used as engineering and implant materials. However, the great potential of the ceramic is hindered by low temperature degradation (LTD) where the ceramic experiencing t-m phase transformation that weakens the properties of 3Y-TZP in the presence of moisture. Two-step sintering was found to be effective in producing fully resistance 3Y-TZY but very long holding time is required. Manganese Oxide (MnO2) is reported as good densification aid at low sintering temperature for 3Y-TZP but the LTD issue is not fully resolved. In this study, the effects of different sintering profiles and dwell time on 3Y-TZP added with 0.5 wt.% of MnO2 were studied in order to improve the resistance towards LTD without affecting the intrinsic properties of the ceramic. The effects of adding 0.5 wt.% of manganese oxide (MnO2) into 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-...
Journal of Nanoscience, 2014
The densification behaviour, mechanical properties, and microstructure of high-purity Al2O3 and CeO2-doped Y-TZP with different weight percentage varied from 0.3 to 1 wt% were investigated. The samples were pressed uniaxially at 200 MPa into rectangular bars and discs and pressureless-sintered at temperature ranging between 1250°C and 1450°C for 2 h while the microstructure was characterized with a scanning electron microscope (SEM). Two-step sintering process works well for temperature higher than 1400°C and it created most tetragonal phase arrangement for stable structure to delay ageing through phase transformation. The mechanical properties in terms of bulk density, Young’s modulus, Vickers hardness, and fracture toughness were also measured. The results indicate that the addition of dopants accelerated the densification parameters and reinforced and toughened the obtained bodies. The maximum values for the mechanical properties of the Al2O3 and CeO2-doped Y-TZP ceramics were 6....
2018
Oxide ion conductors have important applications in oxygen sensors, pumps and SOFCs. The best-known oxide ion conductor is stabilized zirconia with exclusive ionic conductivity at elevated temperature. An understanding of the impact from the use of dopant on the zirconia ceramic is critical for tailoring the fabrication and high temperature operational stability of these devices. The conventional sintering method is time and energy consuming, in contrast to traditional approaches to heat transfer based on radiation and convection, rapid microwave heating allows volumetric heating, thus a potential alternative sintering route to provide accelerated densification with limited grain growth. This research work investigated the effect of manganese oxide (MnO 2) dopant and sintering on the properties of ceria-doped scandia stabilized zirconia (10Sc1CeSZ). Commercially available 10Sc1CeSZ ceramic powder was compared with the powder synthesized via solid state sonication-ball milling method. The results showed that all 10Sc1CeSZ sintered compacts prepared from commercial powder had pure cubic phase, with better resulting mechanical and electrical performance compared to synthesized powder. The effect of MnO 2 additions on the properties of 10Sc1CeSZ was investigated and the results showed that the addition up to 1 wt% had negligible effect on the mechanical properties of the ceramic. The samples containing up to 1 wt% MnO 2 attained above 97.5 % relative density, Vickers hardness of 13-14 GPa and fracture toughness of 3 MPam 1/2. In addition, it was revealed that the 0.5 wt% MnO 2 addition was beneficial in suppressing the cubic zirconia grain growth i.e. the highest average grain size was measured at 4.9 µm when sintered at 1550 C as compared to 9.9 µm measured for the undoped zirconia when sintered at the same temperature. On the other hand, the addition of 5 wt% MnO 2 was found to be detrimental to the densification and
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).
Sintering behavior of tetragonal zirconia polycrystalline powders
Interdependences between the properties of the powder, the compact and the sintered specimen were determined for various TZP powders (tetragonal zirconia, polycrystalline). Tests were conducted to ascertain the impurities content, specific surface and mean crystal size of the powders, the pore-size distribution in the compacts and their shrinkage behavior during sintering at a constant rate of heating. There is a linear relationship between the mean crystal size of a powder and the mean pore diameter of the corresponding compact. The powder agglomerates extensively determine the shape of the compact's pore-size distribution curves. At the early and intermediate stages of sintering, the shrinkage rate is directly dependent on the pore-size distribution of the compact. Quality criteria for the sintering behavior of TZP powders were arrived by correlation pore-size distributions and sintering rates.