Measurement of Mechanical Properties of Single and Multilayered Nitride thin Films Prepared by Cathodic Arc Deposition
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MEASUREMENT OF MECHANICAL PROPERTIES OF SINGLE AND MULTILAYERED NITRIDE THIN FILMS PREPARED BY CATHODIC ARC DEPOSITION A.K. Sikder1, I. M. Irfan1, Ashok Kumar1, 2, Robert Durvin3, Mark McDonough3 and M. D. Smith3 1 Center for Microelectronics Research, University of South Florida, Tampa, FL 33620 2 Also with Department of Mechanical Engineering 3 BryCoat Inc., Safety Harbor, Florida 34695-3403. Mechanical properties of thin films differ significantly from those of bulk materials due to the effects of interfaces, microstructure and thick underlying substrates. In this study we will present the results of nanoindentation tests to evaluate mechanical properties of nitride (TiN, ZrN, CrN, TiCN and TiAlN) thin films. Films were coated on steel substrates using cathodic arc deposition technique. Surface morphology and roughness of the samples are investigated using atomic force microscopy (AFM). Films were also characterized by x-ray diffraction (XRD) technique. Nanoindentation technique along with AFM and XRD methods are very useful for characterizing hard thin coatings. INTRODUCTION: Traditionally the term hard coating refers to the property of high hardness in the mechanical sense with good tribological properties. Coatings are generally classified into two categories, i.e. soft and hard, depending on a hardness value lower or higher than 10 GPa. Demand of multilayered and homogeneous coatings are increasing to improve the tribological properties of a wide variety of mechanical components such as tools for metal cutting and forming, and machine elements such as rolling or sliding bearing surfaces, seals, piston/cylinder systems, and valves [1-3]. Nitrides are used as wear-resistant coatings on the surface of high-speed steel (HSS) because of their ultrahigh hardness, low friction co-efficient and high heat, oxidation, and corrosion resistance properties [4]. A variety of hard coatings are widely used in the tool industry, mainly to reduce friction and to increase wear resistance. One of the mostly widely used and studied coatings to date is TiN, which has beneficial properties including high hardness, low friction, and chemical inertness. In recent years, a new generation of coating, titanium carbo-nitride (TiCN), has been gaining focus. In addition to TiCN, other nitrides such as chromium nitride (CrN), zirconium nitride (ZrN) as well as multi-component nitrides such as TiAlN has been studied. The performance and reliability of these hard coatings are often limited by their mechanical properties. Physical vapor deposited (PVD) TiN and TiN/TiAlN multilayers are currently used in tooling applications achieving an increase in lifetime of up to ten times the normal. In milling processes, the tool lifetime of TiCN coated cemented carbide indexible tips is four times higher than the tool lifetime of TiN coated tips [5]. The advantages in the PVD technology over CVD counterpart are the lower deposition temperature, control over deposition rate, the stoichiometry and nitrogen: carbon ratio, and the availability of not-equilib
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