Effect of sodium tungstate concentration in bath on electrodeposition of nickel-tungsten alloy
[Introduction] The effect of the concentration of sodium tungstate in bath on the properties of Ni-W alloy coating needs to be studied to prepare a wear-resistant Ni-W alloy coating for application in high-temperature environments. [Method] Ni-W alloy coatings with different mass fractions of tungsten were electrodeposited on 20CrMoA steel under direct current by adjusting the mass concentration of sodium tungstate in bath. The effect of the mass concentration of sodium tungstate on the deposition rate, and the W content, morphology, density, microhardness, and high-temperature oxidation resistance of Ni-W alloy coating was studied. [Result] The mass concentration of sodium tungstate in bath had significant impact on the W content of Ni-W alloy coating, which further affected the morphology, internal stress, microhardness, and high-temperature oxidation resistance of Ni-W alloy coating. The Ni-W alloy electrodeposited with 40 g/L of sodium tungstate was smooth, compact, and crack-free, contained 34.82％ (mass fraction) of W, had a density of 10.88 g/cm3 and a microhardness up to 1199.6 HV after being annealed at 500 ℃, and showed much better high-temperature oxidation resistance than the PCrNi3MoVA alloy steel commonly used in the weapon industry. [Conclusion] The results of this paper can provide experimental basis for application of Ni-W alloy coating in high-temperature and high-wear environments such as weapon barrel.
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