Compression Creep Characteristics of 8‐mol%‐Yttria‐Stabilized Cubic‐Zirconia

Abstract

Constant stress compression creep tests were conducted on 8-mol%-yttria-stabilized cubic-zirconia (8YCZ) over stress (), temperature, and grain-size ranges from ϳ20 to 300 MPa, 1673 to 1773 K, and 4 to 8 m, respectively. Creep data were analyzed in terms of the relationship ؔ n , where is the strain rate and n the stress exponent. Although the experimental data yielded a stress exponent of n Ϸ 2, analysis of the results with compensation of significant concurrent grain growth revealed that the true stress exponent was n Ϸ 1. The results were consistent with deformation by the Coble creep mechanism. Experiments at stresses greater than ϳ100 MPa revealed a transition from grain-size-dependent Coble diffusion creep to grain-size-independent intragranular dislocation creep.

Microstructural and high-temperature mechanical characteristics of nickel oxide/zirconia composites for solid oxide fuel cells

“…This result agrees with the difference in creep strength reported for monolithic NiO [18] and 8YSZ [21]. The microstructure after deformation was investigated looking for modifications with respect to the as-fabricated materials.…”

“…The creep parameters n and Q were determined by stress and temperature changes during deformation; values of n =4.5± 0.8 and Q= 560± 70 kJ/mol were estimated for the 40NiO composite. The high stress exponent value suggests that an intragranular creep mechanism is the rate-controlling deformation process, as found in 8YSZ [21] and NiO [18] monoliths strained at high stresses. Regarding the activation energy for creep, the present value is close to that reported for monolithic NiO, 510 ± 60 kJ/mol [18].…”

Ruthenium-containing bond coats for thermal barrier coating systems

“…The steady-state creep stress versus strain-rate relationships for various TBCrelated materials. 23,[44][45][46] ruthenium modifi cation to NiAl-based alloys increases the creep strength over stoichiometric NiAl; therefore, it is necessary to understand the microstructural state of these coatings in relationship to the ternary and higher order phase diagrams.…”

Estimation of Stress Exponent and Activation Energy for Rapid Densification of 8 mol% Yttria‐Stabilized Zirconia Powder

“…On the other hand, there have been limited reports concerning creep deformation of 8Y‐SZP with submicrometer grains, in contrast to the many reports on 8Y‐SZP containing additives (e.g., SiO 2 , Al 2 O 3 , and TiO 2 ). In the case of creep deformation of 8Y‐SZP with grain sizes of ∼5 μm, Sudhir and Chokshi have reported the occurrence of grain size independent power‐law creep with n > 5 and p = 0 at high stresses above 100 MPa and diffusional creep characterized by n = 1 at low stresses below 100 MPa, in contrast to deformation by grain‐boundary sliding ( n = 2) in 3Y‐TZP at ∼10–100 MPa…”