Influence of Co-enriched surface zones in cemented carbides on the microstructure and mechanical properties of TiN/TiC0.6N0.4/ α-Al2O3 coatings

Research output: Contribution to journalArticleResearchpeer-review

Authors

  • Martin Krobath
  • Werner Ecker
  • Christoph Czettl

External Organisational units

  • Materials Center Leoben Forschungs GmbH
  • Ceratizit Austria GmbH
  • Christian Doppler Laboratory of Advanced Coated Cutting Tools

Abstract

In metal cutting applications functionally graded near-surface zones in cemented carbide substrates are applied to optimize their properties, in particular toughness and hardness. Thus, the present work focuses on the influence of Co-enriched substrate surface zones and their thickness on the microstructure and mechanical properties of state-of-the-art TiN/TiC 0.6N 0.4/α-Al 2O 3 coatings synthesized using chemical vapor deposition. Complementary cross-sectional energy dispersive X-ray spectroscopy and electron back-scatter diffraction maps provided insight into the grain size, preferred orientation and phase composition of coatings and substrates. While the hardness and Young's modulus of the coatings were hardly affected by the Co-enriched surface zone and its thickness, nanoindentation maps performed on the cross-sections of the substrates confirmed a lower hardness and Young's modulus in zones with higher Co content. Furthermore, it was found that the Co-enriched surface zone and its thickness have no effect on the thermal crack networks of the coatings. Rockwell-indentation tests demonstrated a reduction of the coating adhesion with increasing thickness of the Co-enriched surface zone. As determined by X-Ray diffraction, the tensile residual stress in both, the TiC 0.6N 0.4 and α-Al 2O 3, decreased with increasing thickness of the Co-enriched surface zone. Complementary finite element method simulations have shown that plastic deformation due to creep in the substrate and the Co-enriched surface zone only has a minor influence on the residual stress in the coating. The results obtained within this work contribute to a better understanding of the influence of a Co-enriched surface zone and its thickness on the performance of TiN/TiC 0.6N 0.4/α-Al 2O 3 coated cutting tools.

Details

Original languageEnglish
Article number106025
Number of pages8
JournalInternational journal of refractory metals & hard materials
Volume110.2023
Issue numberJanuary
Early online date18 Oct 2022
DOIs
Publication statusPublished - Jan 2023