Influence of grain boundary structures of subcritical crack growth in high-performance oxide ceramics

1993 ◽  
Vol 28 (2) ◽  
pp. 133-136
Author(s):  
T. Weiss
Keyword(s):  
Grain Boundary ◽  
Crack Growth ◽  
High Performance ◽  
Subcritical Crack Growth ◽  
Oxide Ceramics

Examination of Fracture Interfaces in Silicon Nitride

1975 ◽  
Vol 33 ◽  
pp. 60-61
Author(s):  
Nancy J. Tighe
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Slow Crack Growth ◽  
Ceramic Materials ◽  
Grain Boundary Sliding ◽  
Boundary Phase ◽  
Turbine Engines ◽  
Boundary Sliding

Silicon nitride is one of the ceramic materials being considered for the components in gas turbine engines which will be exposed to temperatures of 1000 to 1400°C. Test specimens from hot-pressed billets exhibit flexural strengths of approximately 50 MN/m2 at 1000°C. However, the strength degrades rapidly to less than 20 MN/m2 at 1400°C. The strength degradition is attributed to subcritical crack growth phenomena evidenced by a stress rate dependence of the flexural strength and the stress intensity factor. This phenomena is termed slow crack growth and is associated with the onset of plastic deformation at the crack tip. Lange attributed the subcritical crack growth tb a glassy silicate grain boundary phase which decreased in viscosity with increased temperature and permitted a form of grain boundary sliding to occur.

Grain Boundary Nanostructure and High Temperature Plastic Flow in Polycrystalline Oxide Ceramics

2010 ◽  
Vol 638-642 ◽  
pp. 1731-1736 ◽  
Author(s):  
Hidehiro Yoshida ◽  
Koji Morita ◽  
Byung Nam Kim ◽  
Keijiro Hiraga
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
High Performance ◽  
Boundary Segregation ◽  
Doping Effect ◽  
Oxide Ceramics ◽  
Chemical Bonding State ◽  
Performance Functional ◽  
Near Future ◽  
Boundary Diffusivity

High temperature creep and superplastic flow in high-purity, polycrystalline oxide ceramics is very sensitive to a small amount of doping by various oxides. The doping effect is attributed to change in grain boundary diffusivity owing to grain boundary segregation of the doped cations. The doping effect on the grain boundary diffusivity is caused mainly by change of chemical bonding state in the vicinity of the grain boundary segregated with the doped cations. In other words, controlling of grain boundary nanostructure based on the doping process will be a useful way to develop new high-performance functional ceramics in the near future.

scholarly journals Subcritical crack growth in oxide and non-oxide ceramics using the constant stress rate test

2015 ◽  
Vol 9 (4) ◽  
pp. 187-191 ◽  
Author(s):  
Agnieszka Wojteczko ◽  
Radosław Lach ◽  
Kamil Wojteczko ◽  
Paweł Rutkowski ◽  
Dariusz Zientara ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Crack Propagation ◽  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Constant Stress ◽  
Stress Rate ◽  
Oxide Ceramics ◽  
Subcritical Crack Propagation ◽  
Growth Phenomenon ◽  
Rate Test

Fracture toughness is one of the most important parameters for ceramics description. In some cases, material failure occurs at lower stresses than described by KIc parameter. In these terms, determination of fracture toughness only, proves to be insufficient. This may be due to environmental factors, such as humidity, which might cause subcritical crack propagation in a material. Therefore, it is very important to estimate crack growth velocities to predict lifetime of ceramics used under specific conditions. Constant Stress Rate Test is an indirect method of subcritical crack growth parameters estimation. Calculations are made by using strength data, thus avoiding crack measurement. The expansion of flaws causes reduction of material strength. If subcritical crack growth phenomenon occurs, critical value of crack lengths increases with decreasing stress rate due to longer time for flaw to grow before the critical crack propagation at KIc takes place. Subcritical crack growth phenomenon is particularly dangerous for oxide ceramics due to chemical interactions occurring as a result of exposure to humidity. This paper presents results of Constant Stress Rate Test performed for alumina, zirconia, silicon carbide and silicon nitride in order to demonstrate the differences in subcritical crack propagation phenomenon course.

Subcritical crack growth behavior of dispersion oxide ceramics

2010 ◽  
Vol 95B (1) ◽  
pp. 202-206 ◽  
Author(s):  
Armin Kirsten ◽  
Sabine Begand ◽  
Thomas Oberbach ◽  
Rainer Telle ◽  
Horst Fischer
Keyword(s):  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Oxide Ceramics

Subcritical Crack Growth and Long-Term Strength in Rock and High-Strength and Ultra Low-Permeability Concrete

2009 ◽  
Vol 58 (6) ◽  
pp. 525-532 ◽  
Author(s):  
Yoshitaka NARA ◽  
Masafumi TAKADA ◽  
Daisuke MORI ◽  
Hitoshi OWADA ◽  
Tetsuro YONEDA ◽  
...  
Keyword(s):  
Crack Growth ◽  
Subcritical Crack Growth ◽  
High Strength ◽  
Low Permeability ◽  
Term Strength

Precision grain Boundary Engineering in commercial Bi2Te2.7Se0.3 thermoelectric materials towards high performance

2021 ◽  
Author(s):  
Shuankui Li ◽  
Zhongyuan Huang ◽  
Rui Wang ◽  
Chaoqi Wang ◽  
Wenguang Zhao ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Thermoelectric Materials ◽  
High Performance ◽  
General Strategy ◽  
Grain Boundary Engineering

The strong interrelation between electrical and thermo parameters have been regarded as one of the biggest bottlenecks to obtain high-performance thermoelectric materials. Therefore, to explore a general strategy to fully...

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