Influence of Ar ion etching on the surface topography of cemented carbide cutting inserts

In situ substrate cleaning by ion etching prior to physical vapor deposition of hard coatings alters topography and composition of the surface to be coated. Within this work, the influence of Ar ion etching on the surface topography of cemented carbide cutting inserts with different geometries was investigated. The surface of cutting inserts before and after ion etching was evaluated by different scanning electron microscopy techniques to illuminate the effect of ion etching on both, the cutting edges and the flat surface. Additionally, profilometric measurements were carried out to determine changes of the surface roughness and to quantify the removed material by measuring the step height between the etched and un-etched surface. Surface roughness and thickness of the removed layer increased with etching time at constant bias voltage, while the applied voltage had only a minor influence. In addition, energy-dispersive X-ray spectroscopy mappings indicated changes of the surface composition by ion etching due to preferential sputtering of the cobalt binder phase.