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Evaluation of the influence of bias voltage on the corrosion resistance of Al-Nb-N thin films

Abstract:

Niobium Nitride (NbN) and Aluminum Niobium Nitride (AlNbN) thin films were deposited on silicon (100) and steel AISI 4140 substrates through a multitarget r.f. (13.56 MHz) magnetron sputtering system. The target where made using 4N purity Nb and Al and the growth was performed under a gas mixture of Ar/N2, for different substrate polarization voltages, in order to study the effect of polarization voltage on the crystalline structure and electrochemical properties. Steel 4140 is widely used for fabrication of machines components with hardness between 28 and 38 Rockwell C, however life time of this steel is limited by its low wear and corrosion resistance. The XRD pattern of the sample showed predominantly Bragg peaks for the planes (200) corresponding to FCC phase of the AlNbN, hexagonalδ' NbN phase and hexagonal AlN phase. The FTIR analysis showed vibrational modes associated with NbN, AlN and AlNbN bounds. The steel AISI 4140 with and without AlNbN coating were characterized through electrochemical impedance spectroscopy (EIS) and Tafel polarization curves. As a result of this work it was found a voltage polarization dependence on speed corrosion for NbN and Al-Nb-N films.