Fabrication Of Ni-Fe-W Ternary Alloy Coating By Jet Electrodeposition

Ni-Fe-W alloy coating has good wear resistance,high temperature corrosion resistance,thermal shock resistance and other properties,making it possible to replace the chromium coating.However,the conventional preparation method of slow rate of deposition of Ni-Fe-W alloy and coarse grains,the coating performance is not fully utilized.In order to solve this problem,Ni-Fe-W alloy coating with rapid deposition rate and excellent performance was prepared by Jet Electrodeposition.The effects of process parameters,such as main salt concentration,injection rate,current density and temperature,on the deposition behavior,cathodic polarization behavior,properties and structure of Ni-Fe-W alloy coatings were studied.And to determine the optimal process parameters for preparation of Ni-Fe-W alloy coating.The results show that: compared with the conventional Ni-Fe-W ternary alloy coating method,Jet Electrodeposition accelerates the liquid-pHase mass transfer rate,reducing the cathodic concentration polarization and accelerating the deposition rate of the alloy coating.Ni-Fe-W ternary alloy coating was prepared at the same concentration of electrolyte solution.The deposition rate of the Jet Electrodeposition method was 27.3 mg / min,which was more than 20 times of the conventional deposition rate and the current efficiency was over 85%.The depositional parameters have different effects on the deposition behavior of the Jet Electrodeposition: increasing the concentration of the main salt in the electrolyte solution will increase the concentration of metal cations in the vicinity of the cathode and increase the proportion of the hydrated cations involved in the deposition;In addition,the electrolyte solution injection speed and temperature increases,the cathode potential of negative displacement,increased polarization,so that the structure and properties of alloy coating changes: With the increase of the concentration of sodium tungstate in the electrolyte solution,the content of tungsten in the alloy coating increases,and the content of iron in the alloy solution increases with the increase of the concentration of sodium tungstate in the electrolyte solution.And the micro hardness increases.With the increase of the Jet rate of the electrolyte solution,the content of tungsten and iron in the alloy coating increases,the grain size decreases and the micro hardness increases.The percentages of all the elements in the alloy coating are not affected by the current density.However,the increase of the current density promotes the grain refinement of the alloy coating,and the hardness of the coating increases.The results show that Ni-Fe-W ternary alloy coating can be prepared by Jet Electrodeposition: Ni?NH₂SO₃?₂·4H₂O 300 g/L,Na₂WO₄·2H₂O 40 g/L,FeCl₂·4H₂O 2.0 g/L,H₃BO₃ 40 g/L,NiCl₂·4H₂O 10 g/L,Na₃C₆H₅O₇·2H₂O 40 g/L,additives 7 g/L.The optimum technological parameters were as follows: current density 60 A/dm²,injection velocity 4 m/s,electrolyte temperature 60 ?,pH 4.0.The Ni-Fe-W ternary alloy coating prepared under the optimal technological scheme has the following advantages: the appearance is smooth and bright,and the alloy coating has a dense cellular structure under SEM;XRD shows that the alloy coating is face-centered cubic structure with pHase structure Ni₃Fe;The grain size of the alloy coating is small and the micro hardness of the alloy coating is up to 605 HV,which has good wear resistance and corrosion resistance.