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Using controlled low-energy ion bombardment, CrN and Cr2N films were reactively sputtered from a Cr target in a mixed Ar-N2 discharge. Various Cr-N based coating architectures were developed in this work to provide better substrate accommodation than is currently available using monolithic CrN or Cr2N, as well as to build in “load support” for the hard surface layers on more compliant substrates. A series of monolithic and multilayer structures were deposited at low temperatures (<200 °C) to examine the advantages and disadvantages of various coating architectures and ion energies on three substrates: A2 tool steel, 52100 stainless steel, and 2024-aluminum. The optimal operating point for deposition of stoichiometric CrN and Cr2N coatings was determined from analysis of the target state, and supported by in situ ellipsometric measurement of the optical properties of the films during growth. Films were characterized using X-ray, scanning electron microscopy and Rutherford backscattering spectroscopy. Their properties have been evaluated by microhardness, scratch adhesion, and pin-on-disk wear testing. Many of the multilayer coatings gave microhardness values in excess of 2000 HK, often having better adhesion than the single layer films. This was reflected in the wear performance of these films on both A2 and 2024-Al, where no measurable wear was observed in severe dry sliding wear over sliding distances of more than 9000 m against a WC ball. Thus, wear-resistant Cr-N film architectures can be used on some temperature- sensitive and/or compliant substrates to significantly enhance their surface properties.

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Abstract. The development of micro-and nano-electromechanical systems (MEMS/NEMS) makes use of different thin films such as aluminum, gold, silicon, silver, titanium nitride, silicon carbide etc. This study is a research concerning the influence of substrate nature on the tribological and mechanical characteristics of gold thin films elaborated by thermal evaporation method, for space applications. Three different substrates were employed, namely: C45 steel, plastic (polycarbonate) and glass. Atomic force microscopy investigations were performed in order to characterize the obtained thin films at nanoscale. The nanohardness, Young's modulus, roughness and the friction force are some characteristics that were determined. A significant influence of substrate nature on both mechanical and tribological properties of researched gold thin films was marked out. Regarding the topography, the smallest roughness was determined on the gold thin films deposited on glass substrate.

Abstract. Different nitrides such as titanium nitride, chromium nitride and so on are used in a widespread range of applications such as cutting tools, medical implants, and microelectromechanical devices and all that due to their mechanical, physical and chemical properties. The aim of this study is to obtain chromium nitride thin films and to characterize them by atomic force microscopy investigations. The chromium nitride thin films were deposited by reactive magnetron sputtering on silicon substrates. During the deposition process, the discharge current, the argon and nitrogen flows, the pressure inside the chamber and the deposition time were kept constant. A chromium target with a purity of 99.95 % was used. Some of the films were deposited after a chromium buffer layer was previously deposited on the silicon substrate. The deposition was carried out when substrate temperature was at room temperature, at 300 and 500 °C respectively. Once the films were deposited, atomic force microscopy investigations were performed in order to emphasize the influence of the substrate temperature on the topographical, mechanical and tribological characteristics. The results pointed out an important influence of the substrate temperature on topographical, mechanical and tribological properties of the investigated chromium nitride thin films. IntroductionNowadays the interest of researchers in developing new materials and new technologies for obtaining these new materials is growing so that the increasing need of consumers is satisfied. Different types of nitrides such as titanium nitride [1][2][3][4][5], chromium nitride [6-10], and niobium nitride [11][12][13][14][15] and so on are used for applications such as cutting tools, decorative and protective coatings in the automotive industry, microelectronics, biomedical or aeronautical industries, diffusion barrier in microelectronics etc. The use of these kinds of materials is due to their chemical, mechanical, electrical and tribological properties [1, 16]. The characteristics of these ceramics can be obtained by direct current (DC) or radio-frequency (RF) magnetron sputtering [1, 3, 6, 12, 16], laser ablation [4], ion beam assisted deposition [5] and vacuum arc plasma deposition [8] and so on.Chromium nitride awakes researcher interest for MEMS applications due to its good chemical, wear and corrosion resistance, its good thermal stability, high hardness and so forth [6, 7]. Chromium nitride thin films can be used in corrosive and high temperature environments where titanium nitride thin films cannot be used because of its smaller temperature resistance [8]. One of the most used technologies to elaborate such films is magnetron sputtering [6, 7, 17, 18, 19] due to its high deposition rate, its possibility to control the deposition process and due to the low temperature of the substrate during the deposition. Controlling the substrate temperature, the argon and nitrogen flows,

Niobium nitride is used in a wide range of application due to its mechanical, physical, chemical, electrical and optical properties. The main aim of this paper is to deposit niobium nitride thin films by direct current magnetron sputtering and to characterize them at nanoscale. The films were deposited on silicon Si (100) substrates. Three types of films were deposited by modifying the deposition temperature. In this regard, some of the samples were deposited at room temperature (25 °C), some were deposited when the substrate was preheated at 200 °C, and the rest at substrate temperature of 400 °C. Regarding the topography of the samples, an increase in the average roughness was determined with the increase in deposition temperature. The nanoindentation tests were carried out at temperatures between 20 and 100 °C so that to emphasize the change in hardness and modulus of elasticity in terms of testing temperature. The results pointed out an important influence of both the deposition temperature and testing temperature on the topography, adhesion and mechanical properties of the niobium nitride thin films.

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