||Input Sought from Testers of Thermal Spray Coatings for Cohesion
Thermal spray scientists and adhesion testers are sought to examine
and suggest updates to ASTM C 633, Standard Test Method for Adhesion or Cohesive Strength of Flame-Sprayed
Coatings. The test method is being revised by ASTM Committee B08 on Metallic and Inorganic Coatings to include new methodologies.
Those interested should contact Chris Berndt, Ph.D., State University
of New York, at the address that follows, and consult the Web
site, Measurement Technique, Analysis and Critique of the Tensile
Adhesion Test (ASTM C 633) Method at http://dol1.eng.sunysb.edu/Berndt/Berndt-NP34.
A wide range of feedback will be crucial for an effective revision.
The thermal spray industry has experienced advancements in testing
technique, increased applications, and new terminology since the
test method was originally published in 1979.
Technology has changed quite a bit, but its not only that,
said Berndt, vice president, Thermal Spray Society of ASM International.
Its much more of a mature industry than what it was 25 years
back. The whole ball game has really gone to a different league.
Thermal spray is deep seated within the infrastructure of engineering
in America, he continued. Thermal spray coatings that are tested
with C 633 range from hydroxyapatite-coated onto prosthetic implants
for orthopedic and dental devices, thermal-barrier coated turbine
blades for aerospace or power-generating equipment, and coatings
used in paper manufacturing.
The following adjustments to Test Method C 633 have been proposed:
Alter the title to reflect the generic technology of thermal
Define the fracture locus to provide a common grounding in
terminology. This fracture locus needs to be reported for each
For a multi-component system (e.g., a bond coat with a ceramic
overlay), failure at the interface between two coatings is described
as internal adhesive;
Increase the minimum specimen length from 1 to 1.5 inches, or
as agreed upon by the manufacturer and customer; and
Change the specimen attachment system so that a pin coupling
to the tensile testing device is permissible.
Input is actively being sought on these adjustments; all comments
are highly invited.
An ASTM working group of thermal spray engineers, aerospace scientists,
academicians, and corrosion specialists will be involved in the
C 633 revision. As working group chair, Berndt is collecting input
from all corners of industry through his association with ASM,
the Steel Structures Painting Council, the National Association
of Corrosion Engineers, and the American Welding Society. I now
feel that this important standard test method is undergoing a
long overdue revision, he concluded.
For further technical details, contact Chris Berndt, Ph.D., SUNY at Stony Brook, Dept. of Materials Science and Engineering,
306 Old Engineering, Stony Brook, NY (631/632-8507; 632/8525 or
8052). Committee B08 meets April 2-4, 2001, Phoenix, Ariz. For
meeting information, contact Staff Manager Dan Schultz, ASTM (610/832-9716). //
Copyright 2000, ASTM