Abstract
•Fe-Ni-Co-Ti shape memory alloy (Fe-SMA) substrates were pickled at different plasma-treating.•The phase composition, structure, mechanical, and tribological surface characteristics were examined.•The carbonitrided films were improved the corrosion resistance of Fe-SMA samples.•The treated Fe-SMA sample at 450 W had the highest the protection capacity (91.38%).
In this work, Fe-Ni-Co-Ti shape memory alloy (Fe-SMA) substrates were pickled at various plasma-treating powers of 300, 400, and 450 W at a fixed handling time of 15 min. The carbonitriding procedure was achieved by employing a gas blend contains 10% acetylene and 90% nitrogen. The phase composition, structure, and mechanical and tribological surface characteristics were examined using X-ray diffraction (XRD), oscillating ball-on-disk tribometer, optical microscopy, surface profile, and microhardness tester. The plasma carbonitriding treatment demonstrated high surface micro-hardness up to 725 HV0.1 compared with the untreated specimen (220 HV0.1). The corrosion and wear characteristics of the plasma-treated and untreated Fe-SMA surface were assessed by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques in a 1.0 M solution of HCl. The obtained findings indicated that carbonitrided films improve the corrosion resistance of Fe-SMA samples. This improvement was enhanced when the plasma-treating power increased from 300 to 450 W. The treated Fe-SMA sample at 450 W has the highest protection efficiency (91.4 %) and the lowest corrosion current density Icor (1.11 µA cm−2). Moreover, the surface morphology examination approves the corrosion protection of the treated Fe-SMA samples.
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