Abstract
In order to characterize the “Repeating-division type” cracking pattern which is often observed in the brittle coating on a ductile substrate under equi-biaxial tension, the bulge tests were carried out on steel disks with WC-Co coating which was deposited by high-velocity flame spraying. Moreover, an elastic-plastic analysis was applied to the division process of coating to derive the relation among crack interval, tensile stress and strain of substrate at the division, coating and substrate thickness, strength of coating, interfacial strength between coating and substrate, and material's constants. The characteristics of the division process calculated from the analytical equation agree semi-quantitatively well with the experimental results that the crack interval decreases with increasing tensile stress and increases with increasing coating thickness.
