Thermal crack network on CVD TiCN/α-Al2O3 coated cemented carbide cutting tools

Martina Gassner, Nina Schalk, Michael Tkadletz, Christoph Czettl, Christian Mitterer

Research output: Contribution to journalArticleResearchpeer-review

18 Citations (Scopus)

Abstract

TiCN/α-Al 2 O 3 coatings grown by thermally activated chemical vapor deposition (CVD) on cemented carbide cutting inserts typically exhibit a thermal crack network. Although these coated inserts are frequently industrially used for various cutting operations, there is still a lack in understanding of formation and characteristics of these cracks. Thus, the present work focuses on the investigation of the crack network observed on the surface as well as within the layers of CVD TiCN/α-Al 2 O 3 coated cemented carbide cutting inserts. The samples were investigated in different conditions, i.e. in the as-deposited state, after post-treatment by wet-blasting, after annealing, after wet-blasting and annealing, and after face turning, by scanning electron microscopy. Cross-sections of cracked areas were prepared by focused ion beam milling to evaluate crack formation and opening. Further, diffusion processes within the cracks were investigated by energy-dispersive X-ray spectroscopy. While wet-blasting results in closure of thermal cracks near the coating surface due to the introduction of compressive stresses, this effect is equalized after annealing and after turning; cracks are filled with TiO 2 caused by oxidation of the TiCN base-layer and reaction with Al 2 O 3 and – in the case of turning – by workpiece material.

Original languageEnglish
Pages (from-to)1-6
Number of pages6
JournalInternational journal of refractory metals & hard materials
Volume81.2019
Issue numberJune
DOIs
Publication statusPublished - 5 Feb 2019

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