Purpose: This research was done to study the tribological behavior of twist HS6-5-2 drills covered with Cr/CrN/CrN+Cr2N/Cr(C, N) and Cr/CrN/ Cr(C, N) coatings as well as to obtain detailed information about microstructure and properties of investigated coatings. Design/methodology/approach: The coatings were deposited by the ARC-PVD process and examined revealing their microstructure: with the use of SEM and TEM microscopy and composition: chemical (EDS microanalysis) and phase (XRD). Also microhardness, Young’s modulus and adhesion were measured using NHT CSEM hardness tester and scratch tester. Findings: The electron energy disspersive (EDS) analysis of coatings showed higher concentration of nitrogen (in the internal coating-zone) and carbon (in the external coating-zone). The X-ray diffractometry showed that coatings are mainly composed of CrN and Cr2N nitrides. The TEM analysis revealed that coating crystallization starts with nanometric Cr2N nitrides coherent with the ferrite matrix grains. The coatings turned out to improve the lifetime of the drills (much better than that of un-coated ones). Practical implications: The main aim of this work is to determine properties of multilayer and multi-component coatings on basis of Cr, C and N, which are potential candidates for replacing TiN coatings in certain applications. Originality/value: The paper contributes to better understanding of microstructure and properties of the coatings (chemical and phase composition, microhardness, Young’s modulus, adhesion), as well as lifetime of the coated drills.
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