Abstract: An elastic-plastic interface layer between a brittle coating and a ductile substrate is presented to investigate the fracture behavior of the brittle coating on the ductile substrate under the tensile load. Using a modified shear-lag model, the analytical solutions for the distribution laws of the tensile stress developed in the coating, the shear stress developed along the interface and the relationship between the crack density of the brittle coating and the applied strain of the substrate can be obtained. These analytical results are applied to investigate the fracture behavior of a hard and brittle chromium coating on a normal medium carbon steel substrate. The experiment results show that the average saturated crack density of the brittle chromium coating has a good agreement with that predicted by the solution presented .

Key words: Brittle coating, Ductile substrate, Elastic-plastic interface layer, Fracture characterization, Tensile strain