UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2003 Meeting


Section: Solid State Physics and Materials Science


Title:
Microchemical and Microstructural Properties of Metallic Nitride and Carbide Hard Coatings


Authors:
M.Braic, V.Braic, M.Balaceanu, G.Pavelescu, A.Vladescu


Affiliation:
National Institute for Optoelectronics, INOE 2000, P.O.Box MG-05, Bucharest 76900, Romania


E-mail


Keywords:


Abstract:
TiN, TiC, Ti(C,N), ZrN, (Ti,Zr)N and (Ti,Al)N hard coatings were deposited on Si, high speed steel and stainless steel substrates by a cathodic arc system. Various investigation techniques (ERDA, EDX, XPS and XRD) were used to analyze the main microchemical and microstructural characteristics of the films (elemental composition, surface chemistry, phase composition and texture) prepared under different deposition conditions. The deposition parameters were : cathode material – Ti, Zr, Al; reactive gas – N2, CH4, and/or C2H2; gas pressure – 3x10-3 ÷ 1 Pa; arc current – 60 ÷ 120 A; substrate bias voltage – 15 ÷ 220 V; deposition temperature – 160 ÷ 340 0C; deposition time – 15 ÷ 90 min. The experiments showed that the film properties depended mainly on the reactive gas pressure, arc current and, to some extent, on the substrate bias. It is interesting to note that for this deposition method, unlike other systems, the stoichiometry of the compounds did not change for variations of the reactive gas pressure and bias voltage over relatively wide ranges (10-2 – 1 Pa and 20 – 220 V, respectively). As a consequence, other film characteristics such as surface chemistry, phase composition and texture depended only slightly on these parameters within the above mentioned ranges. In the case of TiN films, XPS analysis revealed that a stoichiometric TiN bulk is covered by an oxidized layer consisting of a mixture of Ti2O3 and Ti oxynitride. Most layers exhibited a strong (111) preferred orientation, as it was commonly reported for the films deposited by this methods. This particular orientation was predicted in the deposition conditions in which the strain energy was dominant as compared to the surface energy.