WEB Deformation of an industrial coated WC-Co cemented carbide at the microscaleThursday (24.09.2020) 10:25 - 10:40 F: Functional Materials, Surfaces, and Devices 2 Part of:
WC-Co Cemented carbides (called also hardmetal) is one of the most successful composite materials used in demanding applications like metal cutting and forming. Tool life and performance have been improved tremendously by the deposition of several micrometers thick hard coatings as an external protective layer which made the use of uncoated cutting an exception. Since their introduction, coatings are generally based on transition metal carbide, nitride or carbonitride (CN) owing to their outstanding physical and mechanical properties of both ceramic and metal-like. However, the brittleness and limited ductility is still a major concern for these compounds. As these coatings are not used as a standalone component but rather associated to a substrate with a particular interface, understanding interaction and deformation mechanisms of these components is of a great value. Compression tests of cemented carbides micropillars were already used for evaluating mechanical deformation of these composite compounds. Therefore, this method was proposed and different micropillars from the substrate, coating and at the interface were milled and tested under compression. It is shown that the phase assemblage of Co and WC influences strongly the deformation of the substrate. The new composite hybrid pillar composed of the association of the different components (Substrate/TiN-Interface/Zr(C,N)-Coating) deformed plastically as a unique structure, and even showed the highest strength which outclassed even the coating. The TiN interlayer guaranteed excellent interfacial strength between the substrate and the coating despite the considerable shear stress.