Abstract
Ti0.92Ta0.08N and Ti0.41Al0.51Ta0.08N thin films grown on stainless-steel substrates, with no external heating, by hybrid high-power impulse and dc magnetron sputtering (HiPIMS/DCMS), were investigated for corrosion resistance. The Ta target was operated in HiPIMS mode to supply pulsed Ta-ion fluxes, while two Ti (or Ti and Al) targets were operated in DCSM mode in order to provide a high deposition rate. Corrosion resistance was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy employing a 3.5% NaCl solution at room temperature. The 300-nm-thick transition-metal nitride coatings exhibited good corrosion resistance due to film densification resulting from pulsed heavy Ta-ion irradiation during film growth. Corrosion protective efficiencies were above 99.8% for both Ti0.41Al0.51Ta0.08N and Ti0.92Ta0.08N, and pore resistance was apparently four orders of magnitude higher than for bare 304 stainless-steel substrates.
Highlights
NaCl solutions, with more noble corrosion potentials and lower corrosion currents, than much thicker (1.6 μm) TiN coatings deposited by HiPIMS [45], 1.25-μm-thick TiN coatings deposited by HiPIMS and DCMS [46], 5.3-μm-thick Ti/TiN multilayers deposited by electron-beam evaporation [47], and 2-μm-thick TiN/TiAlN multilayers deposited by DCMS [48]
Electrochemical impedance spectroscopy (EIS) measurements as a function of frequency were performed at open-circuit potential (OCP) with the same cell configuration, area, and potentiostat used in the polarization experiments
The relaxed lattice constant a o of Ti0.92Ta0.08N is 4.28 ± 0.01 Å as and peak shapes for the TM nitride alloys are in agreement with previous X-ray diffraction (XRD) and selected-area determined from XRD
Summary
Refractory transition-metal (TM) nitride thin films are used in a wide variety of applications due to their unique combination of properties, which include high hardness [1,2,3,4,5]; scratch and abrasion resistance [6]; low coefficient of friction [7]; high-temperature oxidation resistance [8,9,10]; and tunable optical [11,12], electrical [11,13,14], and thermal [14], properties. The primary technique employed to obtain dense, hard, low-stress refractory thin films by PVD at reduced growth temperatures has been the use of inert-gas ion irradiation [26,27,28,29] to provide dynamic ion mixing and ion-bombardment-enhanced surface adatom mobilities [26,29,30,31]. Greczynski et al recently reported a novel PVD approach for the growth of dense, hard, and low-stress refractory TM nitride thin films without external substrate heating. [40] TiN was used as an initial model materials system, while employing hybrid high-power impulse and dc magnetron co-sputtering (HiPIMS/DCMS) [40,41,42], with synchronized substrate bias [40,41,42,43], to deposit. NaCl solutions, with more noble corrosion potentials and lower corrosion currents, than much thicker (1.6 μm) TiN coatings deposited by HiPIMS [45], 1.25-μm-thick TiN coatings deposited by HiPIMS and DCMS [46], 5.3-μm-thick Ti/TiN multilayers deposited by electron-beam evaporation [47], and 2-μm-thick TiN/TiAlN multilayers deposited by DCMS [48]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
