“…The solubility of Al 2 O 3 in zirconia is limited, which is reported to be only 0.1 mol% in Y-TZP when sintered at 13001C, 2 and 0.5-1 wt% in 8 mol% YSZ when sintered at 15001C. A recent study 16 that used a similar CRH method seems to support the results of Matsui and colleagues, and reported that sintering activation energy of 8YSZ decreased from 716 to 599 kJ/mol upon 2.16 wt% of Al 2 O 3 addition. It is observed that a small amount of Al 2 O 3 can be sufficient as an effective sintering additive for YSZ by reducing the sintering temperature and promoting densification.…”
Eight mol% of YSZ is considered as one of the most promising electrolyte materials for solid oxide fuel cell. Small amount of Al2O3 is often added to 8YSZ to enhance its mechanical properties and conductivity, as well as to improve its sintering behavior. In this study, the activation energy and sintering kinetics of both undoped and 0.2–2.0 wt% Al2O3‐doped 8YSZ are determined with the help of master sintering curve (MSC). It was found that a better representation of the sintering behavior could be achieved by constructing MSC over two consecutive densification stages with the relative density of 60% set as the boundary. From the activation energy values of the two stages obtained, two densification mechanisms were identified for the undoped and Al‐doped samples. Based on literature data, the possible mechanisms that dominate the two stages were proposed and discussed.
“…The solubility of Al 2 O 3 in zirconia is limited, which is reported to be only 0.1 mol% in Y-TZP when sintered at 13001C, 2 and 0.5-1 wt% in 8 mol% YSZ when sintered at 15001C. A recent study 16 that used a similar CRH method seems to support the results of Matsui and colleagues, and reported that sintering activation energy of 8YSZ decreased from 716 to 599 kJ/mol upon 2.16 wt% of Al 2 O 3 addition. It is observed that a small amount of Al 2 O 3 can be sufficient as an effective sintering additive for YSZ by reducing the sintering temperature and promoting densification.…”
Eight mol% of YSZ is considered as one of the most promising electrolyte materials for solid oxide fuel cell. Small amount of Al2O3 is often added to 8YSZ to enhance its mechanical properties and conductivity, as well as to improve its sintering behavior. In this study, the activation energy and sintering kinetics of both undoped and 0.2–2.0 wt% Al2O3‐doped 8YSZ are determined with the help of master sintering curve (MSC). It was found that a better representation of the sintering behavior could be achieved by constructing MSC over two consecutive densification stages with the relative density of 60% set as the boundary. From the activation energy values of the two stages obtained, two densification mechanisms were identified for the undoped and Al‐doped samples. Based on literature data, the possible mechanisms that dominate the two stages were proposed and discussed.
“…. In this figure, the reported T –ρ curve at a fixed of 0.083 K/s is for pressureless sintering of 8Y‐SZP . As seen in Fig.…”
Section: Resultsmentioning
confidence: 90%
“…(a) and (b). The open squares at bottom and bottom right of the figure represent the relative density as a function of temperature for 8 Y ‐ SZP pressureless‐sintered at a fixed heating rate of 0.083 K/s for comparison.…”
The rapid densification behavior of 8 mol% Y2O3‐stabilized ZrO2 polycrystalline (8Y‐SZP) powder compacts at the initial stage of pressure sintering (relative density (ρ·) below 0.92) has been investigated using an electric current‐activated/assisted sintering (ECAS) system. Data points corresponding to a fixed heating rate were extracted from the densification rate (ρ·) versus ρ and ρ· versus temperature (T) curves. These curves were obtained experimentally by consolidation at a fixed current. Under fixed current ECAS, the heating rate (T·) decreases continuously over sintering time. Using a quasi‐ constant heating rate (CHR) method, data points were extracted to plot ρ· vs. ρ, ρ· vs. T, and ρ vs. T curves at a fixed T·. The stress exponent (n), estimated from a log‐log plot of grain size (d)‐corrected ρ·/ρ and effective stress (σeff) at 1300–1400 K, shows an almost constant value of 1. In addition, the activation energy (Q) for rapid densification, estimated from an Arrhenius plot of d‐corrected ρ·/ρ also shows an almost constant value of 350 kJ/mol, which is considerably lower than the previously reported value of the activation energy for Zr4+ lattice diffusion of about 440 kJ/mol. These results suggest that rapid densification of 8Y‐SZP by ECAS seems to proceed by diffusional creep controlled by grain‐boundary diffusion of Zr4+ ions.
“…That is why it is sintered faster than others. It is a goal that other researchers [3–7] wish to achieve on their nanopowders using various additives, including silica. However, we have already achieved this goal due to our unique nanopowders production technology.Fig.…”
In the present paper the sintering behavior of 3 mol% yttria-stabilized zirconia (3Y-TZP) with and without small amount (0.2 wt %) of SiO2 additive was investigated. It has been studied the silica impact which was added in two ways (co-precipitation and mechanical mixing) on sintering kinetics of 3Y-TZP nanopowders at the initial sintering stage. It was found the silica additive leads to the changing in the predominant sintering mechanism at the initial sintering stage from volume (VD) to the grain boundary diffusion (GBD) in nanopowders obtained by co-precipitation. It was shown that the way of silica addition also significantly influence the sintering kinetics of 3Y-TZP. In case of nanopowders with silica additive obtained by mixing method, sintering process occurred due to the predominance of VD mechanism. It was found that the silica additive and the mechanical activation leads to the acceleration of the sintering process.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
