An analysis of island-delamination type cracking pattern in the brittle film coated on a disk under axisymmetric tension

In order to characterize the island-delamination type cracking patterns in the brittle film on a ductile substrate under uniform tension, an analysis based on energy consideration was carried out to introduce the relation among the size of island-crack, the tensile stress at the formation of island-crack, film and substrate thickness, surface energy of film, interfacial energy between film and substrate, elastic and plastic constants, Poisson ratio and yield strength of film and substrate. The bulge tests Of ceramic and heat-resistant paint films on steel disks show that the size of island-crack increases and the pressure at the formation of island-crack decreases with increase in film thickness. The film thickness dependencies of island size and tensile stress at the formation of island-crack calculated from the analysis agree relatively well with the experimental results. (C) 1998 Elsevier Science Ltd.