Protective oxides formed on CoCrAlY (cobalt, chromium, aluminum and yttrium) coatings. Interim report, 1 October 1985-1 April 1986

Technical Report · Sat Nov 01 04:00:00 EST 1986

OSTI ID:6671005

Aprigliano, L F

The metallic coatings used to protect the hot-section turbine blades of marine gas turbines are often a mixture of cobalt, chromium, aluminum, and yttrium (CoCrA1Y). Using the surface-sensitive technique of x-ray photoelectron spectroscopy, the protective oxide scales on CoCrA1Y coatings containing nominal levels of 20, 29, and 35wt% chromium were found to be essentially the same and were predominantely alumina and a yttrium rich phase that is tentatively identified as yttrium aluminum garnet. As increasing levels of chromium in this coating system are known to improve the coating's hot corrosion resistance, the similarity of the initial scales on all these coatings leads to the conclusion that chromium provides its hot corrosion benefit by slowing the propagation phase of the bulk coating attack.

• Research Organization: David W. Taylor Naval Ship Research and Development Center, Annapolis, MD (USA). Ship Materials Engineering Dept.
• OSTI ID: 6671005
• Report Number(s): AD-A-176137/8/XAB; DTNSRDC/SME-86/52
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
330103 -- Internal Combustion Engines-- Turbine
36 MATERIALS SCIENCE
360205* -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
ALUMINIUM
CHEMICAL REACTIONS
CHROMIUM
COATINGS
COBALT
CORROSION
CORROSION RESISTANCE
DISPERSIONS
ELEMENTS
GAS TURBINES
HIGH TEMPERATURE
MACHINERY
METALS
MIXTURES
OXIDATION
PROTECTIVE COATINGS
SENSITIVITY
SURFACES
TRANSITION ELEMENTS
TURBINE BLADES
TURBINES
TURBOMACHINERY
YTTRIUM