Engineered Interfaces for Adherent Diamond Coatings on Large
Thermal-Expansion Coefficient Mismatched Substrates
Rajiv K. Singh,
D. R. Gilbert,
J. Fitz-Gerald,
S. Harkness,
D. G. Lee
Adhesion of thin or thick films on substrates is a critical issue
in systems where the thermal-expansion coefficients of the coating and
bulk material are significantly different from each other. The large
mismatch of the expansion coefficients results in the generation of
very high stresses in the coating that may lead to delamination,
cracking, or other deleterious effects. A method to increase the
adherence of diamond coatings on tungsten-carbide and stainless steel
substrates is reported based on a substrate-modification process that
creates a three-dimensional thermally and compositionally graded
interface. Scratch and indentation tests on diamond-coated steel and
tungsten-carbide samples did not exhibit film fracture at the interface
and concomitant catastrophic propagation of interfacial cracks.
Department of Materials Science and Engineering, University of
Florida, Gainesville, FL 32611-2066, USA.
