Adherence of Al/sub 2/O/sub 3/ to CoCrAl coatings. [1000-1200/sup 0/C]

Conference · Sat Mar 01 04:00:00 EST 1980

OSTI ID:5270855

Whittle, D P; Boone, D H; Allam, I M

Adhesion between surface scale and protective coating is an essential requirement of a material possessing good overall oxidation resistance. Poor adhesion can lead to exfoliation of the oxide in response to thermal cycling, or mechanically applied stresses, resulting in enhanced oxidation rates. Marked improvements in scale/substrate adhesion can be obtained via the formation of protrusions of oxide growing into the substrate. These act to key the protective scale to the surface and are more effective when a uniform distribution of small oxide pegs can be achieved. Thus, the structure of the coating, the type of rare earth addition, and its concentration are all important and this has been examined using EB-PVD CoCrAl coatings containing a variety of elemental additions. These have been subjected to both isothermal and cyclic oxidation in the temperature range 1000 to 1200/sup 0/C. The coating/scale interface and the development of pegs growing into the coating has been examined in detail by dissolving away the underlying metal + coating using a Br-methanol.

• Research Organization: California Univ., Berkeley (USA). Lawrence Berkeley Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5270855
• Report Number(s): LBL-10607; CONF-800439-4
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360205* -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
ADHESION
ALLOYS
ALUMINIUM
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CHROMIUM ALLOYS
COATINGS
COBALT ALLOYS
CORROSION RESISTANCE
DEPOSITION
ELEMENTS
METALS
OXIDES
OXYGEN COMPOUNDS
PROTECTIVE COATINGS
STRESSES
SUBSTRATES
SURFACE COATING
VERY HIGH TEMPERATURE