Development of PVD-coated cutting tools made of natural rocks

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In order to reduce the dependency on raw materials and the negative environmental influences caused by the production of conventional cutting materials such as tungsten carbide, it is necessary to expand the range of cutting materials. Naturally occurring stones offer potential here. In order to expand the usability of these cutting materials and to enable comparable applications to HSS, there is the perspective of using a technical PVD coating. After a selection of stones that are fundamentally suitable for use as a cutting material as well as for the PVD coating, these are processed using mechanical and chemical coating preconditioning processes. The influence of these preconditioning processes on the subsurface as well as on the coatability and layer adhesion is investigated. With the help of this understanding it is then possible to determine suitable coating systems for stones. The mechanisms of coating adhesion are investigated on the basis of residual stress and coating morphology. Finally, coated stone tools are used for the turning of Al7075 and the coating failure mechanisms are characterised by means of a wear analysis. The originality of the project is characterised by the expansion of the application possibilities of tools made of stone by means of performance-enhancing application of PVD technology.