Damage evolution and stress analysis in zirconia thermal barrier coatings during cyclic/isothermal oxidation.

Journal Article · Mon Oct 01 04:00:00 EDT 2001 · J. Am. Ceram. Soc.

DOI:https://doi.org/10.1111/j.1151-2916.2001.tb01019.x· OSTI ID:943068

Singh, J P; Nair, B; Renusch, D; Sutaria, M; Grimsditch, M

The failure mechanisms of air-plasma-sprayed ZrO{sub 2} thermal barrier coatings with various microstructures were studied by microscopic techniques after thermal cycling. The elastic modulus (E) and hardness (H) of the coatings were measured as functions of the number of thermal cycles. Initially, both E and H increased by -60% with thermal cycling because of sintering effects. However, after -80 cycles (0.5 h at 980{sup o}C), the accumulated damage in the coatings led to a significant decrease of -20% of the maximum value in both E and H. These results were correlated with stresses measured by a spectroscopic technique to understand specific damage mechanisms. Stress measurement and analysis revealed that the stress distribution in the scale was a complex function of local interface geometry and damage in the top coat. Localized variations in geometry could lead to variations in measured hydrostatic stresses from -0.25 to -2.0 GPa in the oxide scale. Protrusions of the top ZrO{sub 2} coat into the bond coat were localized areas of high stress concentration and acted as damage-nucleation sites during thermal and mechanical cycling. The net compressive hydrostatic stress in the oxide scale increased significantly as the scale spalled during thermal cycling.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: EE
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 943068
• Report Number(s): ANL/ET/JA-37255
• Journal Information: J. Am. Ceram. Soc., Journal Name: J. Am. Ceram. Soc. Journal Issue: 10 ; Oct. 2001 Vol. 84; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

36 MATERIALS SCIENCE
DAMAGE
ELASTICITY
HARDNESS
MICROSTRUCTURE
OXIDATION
SPRAYED COATINGS
STRESS ANALYSIS
THERMAL BARRIERS
THERMAL CYCLING
YOUNG MODULUS
ZIRCONIUM OXIDES