Multiscale mechanical and microstrutural characterization of titanium and zirconium carbonitride hard coatings
- Autores: Idriss El Azhari
- Directores de la Tesis: Frank T. Mücklich (dir. tes.), Luis Llanes Pitarch (codir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2020
- Idioma: español
- Materias:
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- Resumen
The present dissertation is an in-depth investigation from the macro to atomic scale of industrial wear-resistant CVD hard coatings deposited on cemented carbides for cutting tool applications. Micro-compression tests at the micro-scale and contact damage induced by means of millimetric spherical indentation were deployed to study deformation mechanisms of two systems consisting of a defined cemented carbide substrate coated with two different films: Ti(C,N) and Zr(C,N). The latter system exhibited a superior tool life in comparison to the conventional Ti(C,N) one. Several characterization techniques were used: confocal microscopy, scanning electron microscopy, focused ion beam, electron back scattered diffraction, X-ray synchrotron and atom probe tomography.
It was found that remnant structural integrity related to the absence of an extensive cracking network for Zr(C,N) - in the as deposited state - is one of the main reasons that could explain better performance in interrupted cutting. Adapted coefficient of thermal expansion toward the substrate, plastic deformation and better cohesive strength at the grain boundaries (which renders more toughness) are factors that contribute not only to this preserved structural integrity but also to the extended tool life during in-service interrupted cutting.
