Materials Chemistry and Physics 125 (2011) 576–586 Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys Enhancement of mechanical and tribological properties in AISI D3 steel substrates by using a non-isostructural CrN/AlN multilayer coating G. Cabrera a , J.C. Caicedo a,∗ , C. Amaya a,b , L. Yate c , J. Mu ˜ noz Salda ˜ na d , P. Prieto a,e a Thin Film Group, Universidad del Valle in Cali, Colombia b Laboratory of Hard Coatings, CDT-ASTIN SENA in Cali, Colombia c Department de Física Aplicada i Óptica, Universitat de Barcelona, Catalunya, Spain d Centro de Investigación y de Estudios Avanzados del IPN, Unidad Querétaro, Mexico e Center of Excellence for Novel Materials – CENM, Calle 13 #100-00 320-026, Cali, Colombia article info Article history: Received 16 February 2010 Received in revised form 5 August 2010 Accepted 14 October 2010 PACS: 68.65.Ac 81.15.Cd 68.55.-a 62.20.Qp Keywords: Multilayers Coatings Vacuum deposition Crystal structure Mechanical properties Tribology Wear abstract Enhancement of mechanical and tribological properties on AISI D3 steel surfaces coated with CrN/AlN multilayer systems deposited in various bilayer periods () via magnetron sputtering has been studied in this work exhaustively. The coatings were characterized in terms of structural, chemical, morphologi- cal, mechanical and tribological properties by X-ray diffraction (XRD), electron dispersive spectrograph, atomic force microscopy, scanning and transmission electron microscopy, nanoindentation, pin-on-disc and scratch tests. The failure mode mechanisms were observed via optical microscopy. Results from X- ray diffraction analysis revealed that the crystal structure of CrN/AlN multilayer coatings has a NaCl-type lattice structure and hexagonal structure (wurtzite-type) for CrN and AlN, respectively, i.e., made was non-isostructural multilayers. An enhancement of both hardness and elastic modulus up to 28 GPa and 280 GPa, respectively, was observed as the bilayer periods () in the coatings were decreased. The sam- ple with a bilayer period () of 60 nm and bilayer number n = 50 showed the lowest friction coefficient (∼0.18) and the highest critical load (43 N), corresponding to 2.2 and 1.6 times better than those values for the coating deposited with n = 1, respectively. The best behavior was obtained when the bilayer period () is 60 nm (n = 50), giving the highest hardness 28 GPa and elastic modulus of 280 GPa, the lowest fric- tion coefficient (∼0.18) and the highest critical load of 43 N. These results indicate an enhancement of mechanical, tribological and adhesion properties, comparing to the CrN/AlN multilayer systems with 1 bilayer at 28%, 21%, 40%, and 30%, respectively. This enhancement in hardness and toughness for mul- tilayer coatings could be attributed to the different mechanisms for layer formation with nanometric thickness such as the Hall–Petch effect and the number of interfaces that act as obstacles for the crack deflection and dissipation of crack energy. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Single layers such as TiCN [1], AlCN [2], YSZ [3], CrAlN [4], BiMnO 3 [5] played an important role a few years ago, due to their chemical, mechanical and tribological properties reflected in higher hardness and toughness, as well as in lower friction coefficients compared to high speed steel, cemented carbide, and other steel substrates used in industrial applications [6]. Nowa- days, these coatings are being mixed, designed and improved in their multilayer coatings structure with periods in the range of nanometers, which some of the advanced coating concepts more commonly investigated during the last two decades, together with ∗ Corresponding author. Tel.: +57 2 339 4610; fax: +57 2 339 3237. E-mail address: jcaicedoangulo@gmail.com (J.C. Caicedo). nanocomposites systems [7,8]. One of these first generation coat- ings, which has been improved by multilayer arrangement, is the CrN, due to the necessity of overcoming the already known fast oxidation of over 700 ◦ C, where properties of hardness and cor- rosion resistance decrease rapidly [9]. In recent years, the CrN coating has been deposited with different nitride coatings as multilayer systems like TiN/ZrN [10], TiCN/TiNbCN, [11] CrN/ZrN [12], WC/CrAlN, CrN/NbN [13,14] and CrN/AlN multilayers. The last one system has shown good results related specifically to the improvement of mechanical properties and oxidation resis- tance as compared to the single layer CrN and CrAlN coatings [4,15]. The enhancement of these properties is attributed to different mechanisms of layer formation with nanometric thick- ness such as the Hall–Petch effect, and the interface numbers that act as obstacles for the inward and outward diffusions of atomic species between layers in the case of oxidation resis- 0254-0584/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.matchemphys.2010.10.014