Kovove Mater. 51 2013 1–10 DOI: 10.4149/km 2013 1 1 1 Cr x N y coatings prepared by magnetron sputtering method M. Béger 1 , P. Jurči 1 *, P. Grgač 1 , S. Mečiar 1 , M. Kusý 1 , J. Horník 2 1 STU, MtF in Trnava, J. Bottu 52, SK-917 24 Trnava, Slovak Republic 2 CTU in Prague, Faculty of Mechanical Engineering, Karlovo nám. 13, CZ-121 35 Prague, Czech Republic Received 17 July 2012, received in revised form 24 October 2012, accepted 7 November 2012 Abstract Chromium nitride coatings were deposited by reactive magnetron sputtering onto sub- strates made from Cr-ledeburitic steel 1.2379. Microstructures, phase constitution, mechan- ical and tribological properties of CrN-coatings were investigated. It has been found that the deposition at given combination of parameters gave dense, fine-grained coatings, having colum- nar structure and very smooth surface. The coatings were formed from Cr2N when low N2 : Ar ratio has been used while they contained CrN at higher nitrogen input into the processing chamber. The Young’s modulus of the coatings was influenced only slightly by the deposition conditions. On the other hand, the hardness of the CrN was higher than that of the Cr2N. The adhesion of the CrN is better than that of Cr2N. The principal explanation is that the Cr2N is brittle in nature and exhibits a strong tendency to cracking and spallation when normally loaded. Generally, the friction coefficient measured against 100Cr6 ball bearing steel was lower than that determined against sintered alumina. Considerable material transfer (adhesion) has been recorded for 100Cr6-steel while no transfer but abrasion has been detected for alumina counterpart. For the alumina counterpart, better tribological behavior has been recorded for the CrN than that for Cr2N, which is consistent with its good adhesion. K e y w o r d s: ledeburitic steel substrate, magnetron sputtering, CrN-coating, microstruc- ture, mechanical properties, tribology 1. Introduction Chromium nitride (Cr x N y ) hard coatings have been developed over the past two decades. They have early gained a great scientific interest due to their good wear- and corrosion resistance, up to very high tem- peratures [1–3]. The chromium nitride coatings are used in a variety of applications such as tools for wood machining [4, 5], cutlery industry [6], ultra-high speed micro-machining [7], automotive industry [8], and bio- medicine [9]. Another important field of their applic- ation is the nuclear industry as hard facing mater- ial due to their excellent anti-galling properties and high thermal stability [10]. Besides that, it is possible to deposit fine-grained CrN-films up to a relatively great thickness (around 7 μm) whereas low internal stresses are kept. This fact together with that CrN is less brittle than TiN, but still quite hard, makes CrN more suitable for surface protection at relatively soft substrates such as aluminum alloys and stainless steels [3]. *Corresponding author: e-mail address: p.jurci@seznam.cz The Cr x N y coatings are generally manufactured by various physical vapor deposition (PVD) meth- ods such as the arc deposition and reactive magnet- ron sputtering [13]. Magnetron sputtering has been developed rapidly over the last decade. This depos- ition technique offers the same or better functionality of the films than the others, but at greater film thick- ness. It now makes a significant impact in application areas including hard, wear-resistant coatings, low fric- tion coatings, corrosion-resistant coatings, and decor- ative coatings [11]. The effect of the nitrogen partial pressure on the phase constitution of magnetron sputtered chromium nitride coatings has been studied extensively [2, 12– 15]. It has been established that the phase constitution of the coatings was changed from the Cr(N) solid solu- tion at very low nitrogen partial pressure to the mix- tures of Cr(N) + Cr 2 N or Cr 2 N + CrN when higher nitrogen partial pressure has been used. At specific conditions, pure either Cr 2 N or CrN were obtained. The opinions on the effect of the nitrogen partial