The adhesion of as-sputtered Pt thin films to NiO single crystals has been characterized by a continuous microscratch technique. In these experiments, a conical indenter was driven into a 1.2 μm thick Pt film at a rate of 15 nm/s, and across the sample surface at a rate of 0.5 μm/s, until a load drop was observed indicating that the film had delaminated. Using the width of the scratch track at the point at which the film delaminated from the substrate, the critical load required for delamination, and the area of the delaminated region, a model has been developed to determine the work of adhesion of the Pt/NiO system. This model uses an elastic contact mechanics approach to relate the stresses acting in a scratch experiment to the strain energy released during film delamination. Using this model, the work of adhesion and hence the interfacial fracture toughness have been determined to be 0.023-0.06 J/m2and 0.07-0.11 MPa✓m, respectively. These values are in reasonable agreement with those determined by other methods for metal-ceramic systems.
Bibliographical noteFunding Information:
This research was supported by the Center for Interfacial Engineering at the University of Minnesota under Grant No. NSF/CDR-8721551 and Corning Incorporated, under Grant No. N00014-89-0164. The authors also gratefully acknowledge the invaluable assistance provided by Dr. Ridha Berriche, of National Research Council, Ottawa, Canada, in carrying out the experiments and by Dr. P.S. Alexopoulos, Dr. T.W. Wu, and Dr. T.C. O'Sullivan, of IBM Almaden Research Center, and Dr. Ridha Berriche of the National Research Council, Canada, in building the microindentation apparatus. The authors also gratefully acknowledge the contributions from He Huang, graduate student in the Department of Chemical Engineering and Materials Science at the University of Minnesota, in the development of the theoretical model.