Adhesion measurements using telephone cord buckles

Thin film adhesion energies can be calculated using buckles with the telephone cord geometry. The buckles can be measured through the point of inflection of the buckle or through the center of the buckle and modeled as a straight buckle of uniform width and height. In the tungsten-silica system, a unique delamination morphology involved a transition from the straight to telephone cord buckle. This structure was used to compare various measurement techniques. The stability range between the straight and telephone cord morphology has been shown to be broader than previously described and exhibits a smooth transition from the straight to telephone cord structure. Measurements of the straight-sided buckles produce adhesion energies which are within 15% of the values calculated when approximating the telephone cord as a straight-sided structure at the inflection point of the buckle.