Analysis of island-delamination type cracking pattern in the brittle film coated on disk under axisymmetric tension
Nakasa Keijiro; Takata Soichiro; Ichigo Hirozo
Abstract:In order to characterize the island-delamination type cracking pattern which appears 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-cracking, the tensile stress at the formation of island-cracking, film and substrate thickness, surface energy of film, interfacial energy between film and substrate, elastic and plastic constants, Poisson's 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-cracking increases and the pressure at the formation of island crack decreases with an increase in film thickness. The film thickness dependency of tensile stress at the formation of island-cracking and the size of island calculated from the analysis agree relatively well with the experimental results. Key Words:island-delamination cracking, surface energy of film, interfacial energy, film thickness, substrate thickness, ceramic film, heat-resistance paint film