Plastic instability of aluminide and platinum modified diffusion coatings during 1100˚C cyclic testing.
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Authors
Manley, Thomas F. II
Subjects
turbine blade coatings
platinum-aluminides
diffusion coatings
IN-738
coating plastic instability
rumpling
cyclic oxidation testing
coating-substrate thermal expansion mismatch
coating surface morphology
platinum-aluminides
diffusion coatings
IN-738
coating plastic instability
rumpling
cyclic oxidation testing
coating-substrate thermal expansion mismatch
coating surface morphology
Advisors
Boone, D.H.
Date of Issue
1985-12
Date
December 1985
Publisher
Language
en_US
Abstract
Platinum modified and unmodified aluminide diffusion
coatings, on a nickel base superalloy (IN-738), were
prepared to test the pre-aluminizing surface roughness
effect on coating oxide scale adherence. A preliminary
study of coating microstructure and surface structure
changes during cyclic oxidation at 1100˚C was begun. During
this testing, significant surface deformation described as
rumpling was observed and attributed to plastic instability
produced during the cycling. Rumpling is found to be a
function of the number and type of thermal strain cycles,
thermal expansion mismatch, coating strength, and coating
thickness. The role of oxide adherence observed for the Pt
modified coatings cannot be determined from the data.
Previous mention of this effect was not found in the
literature. A similar surface rumpling phenomena, however,
has been observed in overlay coating systems under similar
conditions. The mechanical and protectivity impact of
rumpling can only be inferred due to the limited available
data .
Type
Thesis
Description
Series/Report No
Department
Mechanical Engineering
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Funder
Format
77 p.
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.