24-10-2012, 11:19 AM
Crack Growth Analysis of Solid Oxide Fuel Cell Electrolytes. Final Topical Report, January 2002-September 2002
ABSTRACT
Defects and Flaws control the structural and functional property of ceramics. In determining the reliability and lifetime
of ceramics structures it is very important to quantify the crack growth behavior of the ceramics. In addition, because of the
high variability of the strength and the relatively low toughness of ceramics, a statistical design approach is necessary. The
statistical nature of the strength of ceramics is currently well recognized, and is usually accounted for by utilizing Weibull or
similar statistical distributions. Design tools such as CARES using a combination of strength measurements, stress analysis,
and statistics are available and reasonably well developed. These design codes also incorporate material data such as elastic
constants as well as flaw distributions and time-dependent properties. The fast fracture reliability for ceramics is often different
from their time-dependent reliability. Further confounding the design complexity, the time-dependent reliability varies with
the environment/temperature/stress combination. Therefore, it becomes important to be able to accurately determine the
behavior of ceramics under simulated application conditions to provide a better prediction of the lifetime and reliability for
a given component. In the present study, Yttria stabilized Zirconia (YSZ) of 9.6 mol% Yttria composition was procured in the
form of tubes of length 100 mm. The composition is of interest as tubular electrolytes for Solid Oxide Fuel Cells.
ABSTRACT
Defects and Flaws control the structural and functional property of ceramics. In determining the reliability and lifetime
of ceramics structures it is very important to quantify the crack growth behavior of the ceramics. In addition, because of the
high variability of the strength and the relatively low toughness of ceramics, a statistical design approach is necessary. The
statistical nature of the strength of ceramics is currently well recognized, and is usually accounted for by utilizing Weibull or
similar statistical distributions. Design tools such as CARES using a combination of strength measurements, stress analysis,
and statistics are available and reasonably well developed. These design codes also incorporate material data such as elastic
constants as well as flaw distributions and time-dependent properties. The fast fracture reliability for ceramics is often different
from their time-dependent reliability. Further confounding the design complexity, the time-dependent reliability varies with
the environment/temperature/stress combination. Therefore, it becomes important to be able to accurately determine the
behavior of ceramics under simulated application conditions to provide a better prediction of the lifetime and reliability for
a given component. In the present study, Yttria stabilized Zirconia (YSZ) of 9.6 mol% Yttria composition was procured in the
form of tubes of length 100 mm. The composition is of interest as tubular electrolytes for Solid Oxide Fuel Cells.