Surface and Coatings Technology 160 (2002) 145–151 0257-8972/02/$ - see front matter  2002 Elsevier Science B.V. All rights reserved. PII: S0257-8972 Ž 02 . 00330-4 Characterization of TiBN films grown by ion beam assisted deposition S.M. Aouadi *, F. Namavar , T.Z. Gorishnyy , S.L. Rohde a, b a a Department of Mechanical Engineering, University of Nebraska, Lincoln, NE 68588, USA a Spire Corporation, One Patriots Park, Bedford, MA 01730-2396, USA b Received 10 November 2001; accepted in revised form 22 April 2002 Abstract This paper presents one of the first attempts to measure and model the ellipsometric data for ternary nitride coatings in general and TiBN coatings in particular. TiBN coatings with a functionally graded underlayer of TiyTiN have been deposited at low temperatures (-200 8C) on a silicon substrate using ion beam assisted deposition (IBAD). The coating selected for detailed analysis had a total thickness of 1.5"0.2 mm. The deposited structure was characterized post-deposition using X-ray diffraction (XRD), atomic force microscopy (AFM), Rutherford backscattering (RBS), X-ray photoelectron spectroscopy (XPS), infrared spectroscopic ellipsometry (IR-SE), and visible-light spectroscopic ellipsometry (VIS-SE). The primary phases (TiB , TiN, and 2 BN) in the film were identified using XRD. The surface morphology and nanocrystalline nature of the coating (grain size of 5– 7 nm) were deduced using AFM. The chemical composition and phase composition of the sample was determined from RBS and XPS measurements and was subsequently deduced from the analysis of the VIS-SE data. The refractive indices for the constituent phases were deduced from the investigation of TiB TiN and BN single layers with SE. Good correlation was observed between 2, RBS, XPS and VIS-SE for the data on the TiBN sample. XPS and IR-SE suggested that BN formed in the amorphous form. The chemical composition study using these various techniques shows that in-situ SE is a potential technique to control the growth of ternary nitride coatings. Finally, the mechanical properties of the coating were evaluated using a nanoindenter. The hardness and elastic modulus were measured to be 42 GPa and 325 GPa, respectively.  2002 Elsevier Science B.V. All rights reserved. Keywords: Nanocrystal; Nitride; Ellipsometry; X-Ray photoelectron spectroscopy; Rutherford backscattering; Ion beam assisted deposition 1. Introduction In the last 30 years, nitride-based protective coatings have been used in many applications due to their excellent wear, erosion, and corrosion resistance w1–4x. More recently, the addition of boron was found to increase the high temperature stability of these hard coatings. Good corrosion and wear resistance, evident from the low corrosion current density in acid environ- ments w5x, and low abrasion wear volume obtained in wear tests w6x indicate the excellent potential of these coatings in many industrial applications. Some of the *Corresponding author. Tel.: q1-402-472-2380; fax: q1-402-472- 1465. E-mail address: saouadi2@unl.edu (S.M. Aouadi). hard metal boron nitride (MBN) coatings that have been recently deposited include TiBN w7,8x, TiAlBN w9x, TiBCN w6x, and ZrBN w10x. MBN coatings are multiphase materials that have complex phase diagrams. The understanding and control of preferred phases during the deposition of such com- plex materials is the key to the fabrication of coatings with tailored properties yperformance. For example, the hardness and toughness of TiBN coatings was found to be strongly dependent on composition (from 20 to 70 GPa) w11x. Hammer w12x, for instance, obtained a hardness of 55 GPa for TiBN which consists of TiN 0.4 and TiB phases (Fig. 1). As the concentration of B or 2 N is increased either cubic BN (c-BN) andyor hexagonal BN (h-BN) phases start to form. Hexagonal BN is a soft material with a low coefficient of friction and would be an excellent candidate for dry machining applications.