Author(s): J Kusinski, M Rozmus, J Bujak
Purpose: This research was done to study the tribological behavior of twist HS6-5-2 drills covered with Cr/ CrN/CrN+Cr 2 N/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 Cr 2 N nitrides. The TEM analysis revealed that coating crystallization starts with nanometric Cr 2 N 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.