Preparation of nanocrystalline Ni–Mo and Ni–Mo–ZrO2 coating and investigation of its corrosion resistance and wear behaviors.

Nanocrystalline Ni–Mo and Ni–Mo–ZrO 2 coatings were designed and successfully fabricated via electrodeposition process in direct current mode. Impacts of molybdate and ZrO 2 nanoparticles, cathodic current density (i c) on surface, structure and performance of Ni–Mo alloy were analyzed. Electrochemical behaviors were evaluated by electrochemical impedance method in sodium chloride solution. A more compact and consistent surface morphology was prepared by introducing molybdate in nickel. Grain sizes of Ni–Mo alloy decreased as molybdate increased from 2 to 6 g L−1, and enlarged as i c increased. After incorporation of ZrO 2 , the grains initially decreased to 12 nm and later increased to 18 nm. The structure of the deposit is a face-centered cubic phase. With the increase of molybdate content, the preferential Ni (220) crystal plane was changed to oriented (111) plane. The Ni–Mo alloy comprises 91 wt% Ni and 5.4 wt% Mo. R a of Ni–Mo–ZrO 2 was 73 ± 4 nm. Ni–Mo alloys obtained at 20 mA cm−2 and 2 g L−1 molybdate possess the best corrosion-resistant behavior. Incorporation of ZrO 2 can strengthen electrochemical stability and anti-wear behavior of Ni–Mo alloy. The inclusion of ZrO 2 refined the grain size from 18 to 12 nm. The Ni–Mo/ZrO 2 coatings electrodeposited under 2–4 g L−1 Na 2 MoO 4 ·2H 2 O, 20–40 mA cm−2, 10–15 g L−1 ZrO 2 have excellent wear and corrosion resistance. [ABSTRACT FROM AUTHOR]