Sw. Yurgartis et al., MICROCRACK MORPHOLOGY OF AN ADHERENT COATING ON A THERMALLY MISMATCHED SUBSTRATE, Journal of adhesion science and technology, 9(2), 1995, pp. 199-213
It is well known that thermal expansion mismatch between a coating and
a substrate often results in a microcracked coating. Depending on the
degree of adhesion to the substrate, the coating can fracture at the
interface (leading to coating spalling) or the coating can fracture no
rmal to the plane of the interface. The latter is given attention in t
his paper. A better understanding of the mechanics and the performance
of coatings requires an improvement in the quantification of the coat
ing crack morphology. This work proposes and implements a variety of c
oating crack morphology measurements. Characterization has been accomp
lished via section and plan views. Specimen preparation techniques and
digital image processing approaches have been developed to make measu
rements feasible. A data set from a chemically vapor deposited SiC-coa
ted carbon-carbon composite substrate is given. The data obtained are
used to propose two simplified models of the coating crack morphology.