Actions for Crack Driving Forces in a Multilayered Coating System for Ceramic Matrix Composite Substrates

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Crack Driving Forces in a Multilayered Coating System for Ceramic Matrix Composite Substrates

Author
Miller, Robert A.
Published
September 2005.
Physical Description
1 electronic document
Additional Creators
Ghosn, Louis J. and Zhu, Dongming
Online Version

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Summary
The effects of the top coating thickness, modulus and shrinkage strains on the crack driving forces for a baseline multilayer Yttria-Stabilized-Zirconia/Mullite/Si thermal and environment barrier coating (TEBC) system for SiC/SiC ceramic matrix composite substrates are determined for gas turbine applications. The crack driving forces increase with increasing modulus, and a low modulus thermal barrier coating material (below 10 GPa) will have no cracking issues under the thermal gradient condition analyzed. Since top coating sintering increases the crack driving forces with time, highly sintering resistant coatings are desirable to maintain a low tensile modulus and maintain a low crack driving force with time. Finite element results demonstrated that an advanced TEBC system, such as ZrO2/HfO2, which possesses improved sintering resistance and high temperature stability, exhibited excellent durability. A multi-vertical cracked structure with fine columnar spacing is an ideal strain tolerant coating capable of reducing the crack driving forces to an acceptable level even with a high modulus of 50 GPa.
Other Subject(s)
Collection
NASA Technical Reports Server (NTRS) Collection.
Note
Document ID: 20050215687.
NASA/TM-2005-213835.
E-15205.
29th International Conference on Advanced Ceramics and Composites; 23-28 Jan. 2005; Cocoa Beach, FL; United States.
Terms of Use and Reproduction
No Copyright.
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