Analysis of repeating division and delamination processes of sprayed WC-Co coating under biaxial tension
Gao Sande; Nakasa Keijiro; Kato Masahiko
Abstract:In order to characterize the 'Repeating division type' cracking pattern which is often observed in brittle coating on a ductile substrate under increasing biaxial tensile stress, the bulge tests were carried out on steel disks with WC-Co coating which were prepared by high velocity flame spraying. Moreover, an elastic analysis was applied to the division process of coating to derive a relation among the crack interval, the tensile stress and strain of substrate at the division, coating and substrate thickness and material's constants. The characteristics of the division process calculated from the analytical equation agree qualitatively well with the experimental results that the crack interval decreases with an increase in tensile stress and the crack interval is large when the coating thickness is large at the same stress. Key Words:spray coating, biaxial tension, cracking pattern, repeating-division, elastic and plastic analysis