Adhesive and cohesive properties of nanostructured Zr02 coatings by the original Vickers Indentation Cracking technique

In order to characterize the adhesion of nanostructured plasma-sprayed Y2O3–ZrO2 coatings presenting some geometrical specificities, it is here suggested to apply the Vickers Indentation Cracking (VIC) technique, which is capable of initiating a crack at the interface by performing the indentation test close to the interface within the substrate. This method renders it possible to overcome the difficulties concerning the characterization of the adhesion of nanostructured Y2O3–ZrO2 (YSZ) coatings. It was suggested to calculate an adhesive stress parameter by employing two physical parameters, i.e., the critical load to initiate the crack and the indentation distance measured between the interface and the indent center. In addition, for the case of brittle coatings, the crack was found to deviate from the interface toward the coating. Under such conditions and on the basis of the critical point (given by the two parameters: load and indentation distance), a stress parameter representative of the cohesive properties of the coating was defined according to the crack deviation conditions.