Accession Number:

ADA413960

Title:

Surface Cracking and Interface Reaction Associated Delamination Failure of Thermal and Environmental Barrier Coatings

Descriptive Note:

Technical Memorandum

Corporate Author:

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CENTER

Report Date:

2003-04-01

Pagination or Media Count:

12.0

Abstract:

In this paper, surface cracking and interface reactions of a BSAS coating and a multi-layer ZrO2-8wtY2O3 and mulliteBSASSi thermal and environmental barrier coating system on SiCSiC ceramic matrix composites were characterized after long-term combined laser thermal gradient and furnace cyclic tests in a water vapor containing environment. The surface cracking was analyzed based on the coating thermal gradient sintering behavior and thermal expansion mismatch stress characteristics under the thermal cyclic conditions. The interface reactions, which were largely enhanced by the coating surface cracking in the water vapor environment, were investigated in detail, and the reaction phases were identified for the coating system after the long-term exposure. The accelerated coating delamination failure was attributed to the increased delamination driving force under the thermal gradient cyclic loading and the reduced interface adhesion due to the detrimental interface reactions.

Subject Categories:

  • Coatings, Colorants and Finishes
  • Metallurgy and Metallography
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE