Electrochemical Deposition Thickness Of NiCoCr Protective Coatings

As the development and demand of modern science and technology and modernindustry, many requirements on the performances of the material has been put out. At thesame time, the performance of the material surfaces have higher requirements, so as tomake the material surface treatment technology has a good development space.Electrochemical deposition is one of the most effective methods of surface treatmenttechnology. Single metal coating is difficult to meet the various performance requirementsof metal coating. Many of the surface of the alloy coatings have a variety of performances,so many alloy coatings can provide more choices for professionals. As a result, it has ahigh attention on the electrochemical deposition of alloy coating technology by theresearchers, especially under the condition of some harsh, used in metal materials specially,such as under the condition of high temperature steam or supercritical water, need toimprove the corrosion resistances of materials and increase the service life of materials.Because of Ni-Co-Cr alloy coating has good surface properties and make it become one ofthe researches focus.This article adopts the method of electrodeposition of preparation of Ni-Co-Cr ternaryalloy coating, and affecting the plating solution composition, process conditions, currentefficiency, such as pH value, solution temperature, and testing of corrosion resistance ofthe coating, the combination of coating performances, surface microstructures and thecomposition of plating, etc., by single factor, this paper has a detailed study the salt ionconcentrations in the solution, the concentrations of the solution concentration of complexagent, wetting agent, concentration of boric acid, deposition time and current density onthe content in the alloy plating metal, surface morphology and the electrochemicalproperties, the structure of the alloy coating and current efficiency.The results show that based on single factor experiment to explore the composition ofalloy coatings, can get optimization of plating solution composition for: NiSO4·6H2O is170g/L, NiCl2·6H2O as30g/L, CoSO4·7H2O as35g/L, CrCl3·6H2O is100g/L, citric acidof100g/L and sodium citrate is200g/L, boric acid is40g/L, sodium dodecyl sulfate is0.18g/L, saccharin is1.4g/L, current density is100mA/cm2, pH is3, the temperature is 40℃, electroplating time is80min. In the above conditions of Ni-Co-Cr ternary alloyplating light, compact and Ni content in the alloy coating on45~50%, the content of Coin45~50%, the content of Cr is around5%, current efficiency is about45%.The optimalconditions of Ni-Co-Cr ternary alloy plating on corrosion resistance of the best. Optimalalloy coatings in3.5wt.%NaCl solution is obtained by polarization curve calculation ofcorrosion current of7.7223×10-8A/cm2, polarization resistance of407877·cm2. Thesurface of Ni-Co-Cr ternary alloy coating on the surface of the dense uniform andrelatively smooth and gloss coating is better. Through binding force experiment tests foundNi-Co-Cr alloy coating after bending experiments, the breakup of the coating and thesubstrate without peeling and falls off phenomenon. This suggests that the adhesionstrength of the alloy coating with copper substrate is good. The surface of Co is in theform of β-Co, Co is face-centered cubic crystal structure;Cr is face-centered cubic crystalstructure,too.The crystal orientations of Ni and Co are (111),the crystal orientation of Cr is(210).