Effect of local curvature of the coating-substrate interface on deformation and fracture of ceramic coatings under uniaxial tension

Scanning electron microscopy and atomic force microscopy have been applied to study the fracture of SiAlN coatings on Cu substrates under uniaxial tension. It is shown that coating spalling occurs in the zones of local curvature of the SiAlN-Cu interface which form due to dislocation glide in the substrate. Preliminary ion bombardment of the substrate suppresses dislocation-induced kinking at the coating-substrate interface and increases the adhesive strength of the coatings, thus preventing their edge delamination. At the same time, the wavy coatingsubstrate interface resulting from ion bombardment gives rise to normal stresses that lead to the buckling and spalling of the coatings in the zones of positive local curvature of the interface.