TY - JOUR

T1 - Thermal crack network on CVD TiCN/α-Al2O3 coated cemented carbide cutting tools

AU - Gassner, Martina

AU - Schalk, Nina

AU - Tkadletz, Michael

AU - Czettl, Christoph

AU - Mitterer, Christian

PY - 2019/2/5

Y1 - 2019/2/5

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=85061354054&partnerID=8YFLogxK

U2 - 10.1016/j.ijrmhm.2019.02.006

DO - 10.1016/j.ijrmhm.2019.02.006

M3 - Article

VL - 81.2019

SP - 1

EP - 6

JO - International journal of refractory metals & hard materials

JF - International journal of refractory metals & hard materials

SN - 0263-4368

IS - June

ER -