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.
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.
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