Electrodeposition and Characterization of Ni–W–Cr2O3 Nanocomposite Coating

Abstract

In this paper, compact Ni-W and Ni-W-Cr 2 O 3 nanocomposite coatings were deposited on mild steel substrates by DC electrodeposition method. The surface morphology, elemental composition, and structure of the obtained coatings were investigated by scanning electron microscopy, energy dispersive spectrometer, and x-ray diffraction. The corrosion resistance was evaluated by potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy. It is shown that incorporation of Cr 2 O 3 nanoparticles into amorphous Ni-W coating would transform its structure into crystalline and influence its properties. The microhardness of Ni-W-Cr 2 O 3 nanocomposite coatings (717-764 HV0.1) is significantly bigger than that of Ni-W coating (687 HV0.1). In addition, with increase of Cr 2 O 3 addition in the electroplating bath, a tendency of improvement in hardness and corrosion resistance performance is observed. Finally, an excellent Ni-W-Cr 2 O 3 nanocomposite coating with a slightly lower resistance and much higher hardness compared with Ni-W coating is electrodeposited in the bath containing 20 g/L Cr 2 O 3 nanoparticles.

Synthesis and Characterization of Ni–W/Cr2O3 Nanocomposite Coatings Using Electrochemical Deposition Technique

“…At 20 g•L −1 , the coatings display a more amorphous tendency characterized by cavities. Similar observations were reported by Zhang et al [21].…”

“…At 20 g•L −1 , the coatings display a more amorphous tendency characterized by cavities. Similar observations were reported by Zhang et al [21]. From the current efficiency analysis, it was found that Ni-W coatings with 11.0 wt.% W content had a current efficiency of 42.05% compared to 32.82% for Ni-W/Cr2O3 electrodeposited with 10 g•L −1 Cr2O3 nanoparticles.…”

“…It can be seen that the microhardness increasede with increase in the content of Cr 2 O 3 in the coatings, such that all the Ni-11.0W/Cr 2 O 3 nanocomposite coatings exhibited better microhardness compared to the purely Ni-W alloy coatings. Similar observations were made by Zhang et al [21]. Ni-W binary alloy coatings fabricated under similar conditions exhibited microhardness of 498 HV.…”

“…Coatings 2019, 9, x FOR PEER REVIEW 11 of 20 W in all EDS pictographs owing to the absence of ammonium chloride in the electrolyte solutions. It is evident that the predominant element in the coatings was Ni, which sees a deviation from results reported by Zhang et al [21]. This can be related to the composition of electrolyte bath used.…”

“…Also, an improvement in corrosion resistance was reported with incorporation of Cr 2 O 3 nanoparticles as a result of the combined increase in both Cr 2 O 3 and Co in the Ni-Co nanocomposite coatings. Zhang et al [21] electrodeposited Ni-W/Cr 2 O 3 with a constant current density of 4 A•dm −2 . However, research on the wear properties of electrodeposited Ni-W/Cr 2 O 3 has not been done.…”