Deformation Microstructures Near Vickers Indentations in SNO₂/SI Coated Systems

Abstract

The micromechanical properties (hardness and brittleness) of the hard-on-hard SnO₂ ∕ Si-coated system (CS) and their modification depending the on load value has been studied. A nonmonotonic changing of microhardness with load growth was detected. The brittle/plastic behavior of the rigid/hard-on-hard SnO₂ ∕ Si CS and its response to concentrated load action explains it.A specific evolution of the indentation-deformed zone vs. load value attributed to the change in the internal stress redistribution between film and substrate was detected. It results in a brittleness indentation size effect (BISE) of the SnO₂ ∕ Si CS revealed in this experiment.It was shown that the greater portion of internal stresses under indentation is concentrated in the coating layer at small loads. This fact causes a strong elastic–plastic relaxation in the film and its delamination from substrate. The increase of brittle failure in the indentation-deformed zone with a decrease of indentation load was revealed.