Study of cathode current effect on the properties of CrAlSiN coatings prepared by LARC M. Har  s  ani * , M. Sahul, P. Zackov  a,  L.  Caplovi  c Institute of Materials Science, Faculty of Materials Science and Technology, Slovak University of Technology in Bratislava, J. Bottu 25, 917 24 Trnava, Slovakia article info Article history: Received 8 July 2016 Received in revised form 25 January 2017 Accepted 28 January 2017 Available online 31 January 2017 Keywords: CrAlSiN hard coatings LARC Deposition parameters Properties abstract The aim of this paper is to investigate effect of cathode current on the properties of a series of CrAlSiN nanocomposite monocoatings prepared by the lateral rotating cathodes arc technique using the PLATIT p 80 þ DLC coating device and were deposited onto high speed steel HSS 6-5-2-5. The influence of the cathode arc current as well as increasing in the Al and Si content were studied in order to determine the coating properties. A sudden change of preferred orientation from (111) / (002) was observed in the interval from 1.3 to 1.7 at. % of Si, and 13.0 to 15.0 at. % Al, respectively. This change of preferred orientation is due to the incorporation of Al and Si into coatings, which also leads to an increased volume of Si 3 N 4 matrix. All as-deposited coatings exhibit continuous nanohardness increment from 30 ± 1.8 to 34.2 ± 1.5 GPa with increasing Al þ Si due to strengthening the solid solution and precipitation of the Si 3 N 4 silicon nitride from the saturated CrAlSiN lattice at ~2.3 at. % of Si. Coatings deposited with cathode current ratio (CCR)  1.00 satisfy the H/E*  0.1 condition for simultaneously hard and tough coatings. The chemical composition, XRD structure, residual stresses, surface roughness and nanohardness were systematically characterised using a scanning electron microscope (SEM) fitted with Energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), laser scanning confocal microscope (LSCM) and nanoindentation. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction The increasing demand for high performance coatings has led to the production of coatings which are becoming more sophisticated in terms of their engineered microstructure and properties [1]. Deposition processes and technologies as well as the nature of coatings are rapidly changing to keep pace with advanced tech- nologies and the requirements for the machining of materials. Therefore, a coating must be prepared in order to achieve the best properties that are limited in the use of high-tech applications and/ or high speed machining. Nanostructured coatings have recently attracted increased interest because of the possibilities of synthe- sizing materials with unique physical-chemical properties [2]. Hard and superhard coatings exhibit excellent hardness, toughness, oxidation resistance and thermal stability, outstanding resistance to wear and abrasion, and low thermal conductivity [3,4]. CrAlN coatings show high hardness and high thermal stability together with excellent oxidation resistance [5]. However, the properties of the CrAlN coatings may be further improved by addition of Si. The addition of Si suppresses the grain growth and refines it. Many authors report [5e9] that Si segregates as amorphous SixNy along the grain boundaries and is reported to prevent the generation of dislocations in the grains due to its nanometric size, and hinder crack propagation by grain boundary enhancement [2,5,6,8,10e12]. Crystalline CrAlN grains become embedded into this amorphous phase (matrix), thus creating the nanocomposite structure [8,13]. Another improvement in the material properties by the addition of Si is the suppression of the of fcc-(Al 1-x Ti x )N decomposition up to the temperature of 1100  C [14]. An approximately one monolayer thin amorphous Si 3 N 4 layer is formed during deposition and this avoids the decomposition and softening of the nanocrystalline grains, which typically occurs at about 800e900  C. This thin amorphous matrix suppresses the diffusion of Al out of metastable Al 1-x Ti x N to stable würtzite h-AlN with a decrease in the hardness [14]. The superhardness of quaternary CrAlSiN coatings, with a hardness 40 GPa [15e17], have better mechanical and tribological properties than CrN, TiN, CrAlN or AlTiN. For this reason, (super) * Corresponding author. E-mail addresses: marian.harsani@stuba.sk (M. Har s ani), martin.sahul@stuba.sk (M. Sahul), paulina.zackova@stuba.sk (P. Zackov a), lubomir.caplovic@stuba.sk (  L.  Caplovi c). Contents lists available at ScienceDirect Vacuum journal homepage: www.elsevier.com/locate/vacuum http://dx.doi.org/10.1016/j.vacuum.2017.01.029 0042-207X/© 2017 Elsevier Ltd. All rights reserved. Vacuum 139 (2017) 1e8