Barrier Height at the Metal/Polymer Interface as an Indicator of the State of the Metal under Cyclic Deformations

The dependence of the potential barrier height at the metal/polymer interface on the number of elastic deformation cycles of the metal was studied. The objects of the study were structural steel and a wide-bandgap dielectric polymer from the poly(arylene phthalide) class, poly(diphenylene phthalide). It was found that the dependence has a complex form with a periodic component. With a relatively small number of deformation cycles, a sharp decrease in the barrier height is observed, and then small fluctuations. The barrier height increases as the number of cycles approaches the threshold value at which the sample fracture occurs. Immediately before the fracture, a sharp decrease in the potential barrier height is observed. In this case, the polymer film can transition to a state with high conductivity. That is, electronic switching occurs. The absolute change in the barrier height was ∼250 meV, and the change in resistance from 2 to 6 orders of magnitude, which can be used to develop a method for non-destructive testing of the state of metals.