| Abstract |
| Multilayered WC-Cr_(1-x)Al_(x)N coatings were deposited on AISI D2 steel by cathodic arc ion plating process (CAIP). The Al concentration was controlled by using evaporation source for Al and fixing the evaporation rate of the other metals (WC alloy and Cr). Five types of WC-Cr_(1-x)Al_(x)N were deposited, i.e., WC-Cr_(0.6)Al_(0.4)N, WC-Cr_(0.57)Al_(0.43)N, WC-Cr_(0.53)Al_(0.47)N, WC-Cr_(0.48)Al_(0.52)N, and WC-Cr_(0.45)Al_(0.55)N. The corrosion behavior in deaerated 3.5 wt.% NaCl solution for the prepared samples was investigated by electrochemical tests (potentiodynamic polarization test, galvanic corrosion test, electrochemical impedance spectroscopy (EIS)) and surface analyses (scanning electron microscopy (SEM), X-ray diffractometry (XRD), glow discharge optical emission spectroscopy (GDOES), and electron probe micro analyzer (EPMA)). The results from potentiodynamic polarization test showed that the WC-Cr_(0.48)Al_(0.52)N coating with the lower porosity (0.144) enhanced the corrosion resistance. Galvanic corrosion test was accomplished using the galvanic couple between the substrate and the WC-Cr_(1-x)Al_(x)N coating. The WC-Cr_(0.6)Al_(0.4)N showed a higher galvanic current density. In EIS measurements, the WC-Cr_(0.48)Al_(0.52)N coating showed an increased charge transfer resistance (R_(ct)). The measured electrochemical tests indicated that the WC-Cr_(0.48)Al_(0.52)N coating with the lower corrosion current density (3.023 μA/㎠) and higher charge transfer resistance (158.7 kΩ㎠) enhanced corrosion resistance. |
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| Key Words |
| Multilayerd coating, CAIP, Galvanic corrosion test, EIS, Porosity, Scratch adhesion test |
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