Structure–property relations in ZrCN coatings for tribological applications E. Silva a , M. Rebelo de Figueiredo b , R. Franz b , R. Escobar Galindo c,d , C. Palacio e , A. Espinosa e , S. Calderon V. a, ⁎, C. Mitterer b , S. Carvalho a a Universidade do Minho, Dept. Física, Campus de Azurém, 4800-058 Guimarães, Portugal b Christian Doppler Laboratory for Advanced Hard Coatings, Department of Physical Metallurgy and Materials Testing, University of Leoben, Franz-Josef-Str. 18, 8700 Leoben, Austria c Centro de Micro-análisis de Materiales (CMAM-UAM), Cantoblanco, 28049, Madrid, Spain d Instituto de Ciencia de Materiales de Madrid (ICMM -CSIC), Cantoblanco, 28049, Madrid, Spain e Departamento de Física Aplicada (CXII), Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain abstract article info Article history: Received 1 January 2010 Accepted in revised form 29 August 2010 Available online 7 September 2010 Keywords: ZrCN PVD Magnetron sputtering Metal-containing coating Hardness Tribology ZrCN coatings were deposited by dc reactive magnetron sputtering with N 2 flows ranging from 2 to 10 sccm in order to investigate the influence of the nitrogen incorporation on structure and properties. Information about the chemical composition was obtained by glow discharge optical emission spectroscopy and Rutherford backscattering spectroscopy. The evolution of the crystal structure studied by X-ray diffraction revealed the formation of a face-centred cubic ZrCN phase for N 2 flows greater than 4 sccm. Additionally, the presence of an amorphous phase in the coatings deposited with the highest N 2 flows could be evidenced by Raman spectroscopy and X-ray photoelectron spectroscopy. This phase can act as a lubricant resulting in a low coefficient of friction as shown in the conducted ball-on-disc tests. Nanoindentation measurements showed that coatings deposited with a 6 sccm N 2 flow had the maximum hardness which also revealed the best performance in the conducted dry cutting tests. © 2010 Elsevier B.V. All rights reserved. 1. Introduction The increasing demand of new materials with enhanced mechan- ical and tribological properties has strongly encouraged investigations in the field of surface engineering and a wide variety of coatings like diamond-like carbon, transition metal nitrides, carbides and carboni- trides have been developed [1–20]. Among the transition metal nitrides and carbonitrides, Ti-based coatings have been extensively studied and evaluated with respect to industrial applications [8,15]. However, despite the fact that ZrN films have good characteristics concerning hardness, corrosion resistance and tribological perfor- mance and, similar to TiCN, significant improvements by carbon addition can be expected, studies concerning the synthesis and properties of ZrCN coatings are quite scarce. Researchers that investigated ZrCN coatings reported on the synthesis by chemical vapor deposition (CVD) [2,5] and physical vapor deposition (PVD) [2,3,6,7,21] techniques. Rie et al. [5] obtained a ZrCN coating with a dense columnar structure by plasma-assisted CVD. Structural investigations by Larijani et al. [7] showed a variation of the lattice parameter due to the substitution of N atoms by C in the ZrN crystal lattice. Since both compounds, ZrN and ZrC, form a solid solution over the entire composition range, the change of the lattice parameter is in agreement with Vegard's law. Measured hardness values reach up to 1040 HK0.01 [5], 3600 HV0.1 [3], 2500 HV [7] and 28.0 GPa [4] while the highest values are typically observed for a C/N ratio slightly exceeding 1. Investigations by Gu et al. revealed a good corrosion resistance for ZrCN coatings deposited by arc-evaporation which are promising results for the use of these coatings in decorative applications. In terms of cutting behaviour, Kudapa et al. combined TiCN with ZrCN deposited by medium temperature CVD and found an improved abrasion wear resistance and prolonged tool lifetime in machining of nodular iron and 4340 low-alloyed steel [2]. In general, the studies carried out so far indicated that ZrCN coatings could be a promising material in a wide variety of mechanical devices, but studies relating the structure of ZrCN coatings to their properties including mechanical and tribological properties as well as the cutting performance are rare. In the present work, ZrCN coatings were synthesized by dc reactive magnetron sputtering. The study addresses the influence of the nitrogen concentration on the structure and properties of the coatings, in particular mechanical and tribological properties as well as cutting behaviour. For the latter ZrCN coatings have been deposited onto cermet cutting tools and were compared with a commercial coating serving as a reference for the tests under dry cutting conditions. 2. Experimental part ZrCN coatings were deposited on (100) single crystalline silicon wafers, high-speed steel (AISI M2) and WC–Co “TNMG 16 04 08-QM H13A” cutting tools for turning by dc reactive magnetron sputtering in an Ar/N 2 /C 2 H 2 atmosphere. The deposition system consists of two Surface & Coatings Technology 205 (2010) 2134–2141 ⁎ Corresponding author. E-mail address: secave44@gmail.com (S. Calderon V.). 0257-8972/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.surfcoat.2010.08.126 Contents lists available at ScienceDirect Surface & Coatings Technology journal homepage: www.elsevier.com/locate/surfcoat