Abstract

Fracture mechanical properties of metallic, thermally sprayed layers made of NiCr, NiCrAlY, molybdenum, and NiCrBSi were characterized using an indentation process close to the edge, known as edge chipping. Thermally sprayed layers were assessed according to their relative fracture toughness. The indentation took place in a vacuum chamber of a scanning electron microscope, which enables positioning in the micrometer range and in-situ observation of crack growth. The evaluation of preliminary indentation tests on a choice of thermally sprayed nickel based alloys failed for different indenter geometriy in most cases due to the porosity and the plasticity of the coating material avoiding a defined crack formation and propagation even at very high loads. Scaling down from macroscopic dimension to the micro range is feasible for edge chipping. It can be applied on coatings considering the anisotropic properties parallel and perpendicular to the substrate surface. Paper includes a German-language abstract.

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