Polytechnic Study On The Two Membrane Three Room Electroplate Of Cr

The Chromium is a material with higher melting point,boiling point and rigidity.Cr(â…¥)electroplate technics exist grievous contaminative question.Separate out potential of Chromiun is relatively negative and overpotential of hydrogen is low in Cr electrode.The current efficiency of deposition chromium is very low for the low separating potential itself and the drastic hydrogen separating reaction resulted by its overpotential. overpotential achieved under different conditions is also highly lacked. Cr(â…¢)electroplate is hardly any virulence and energy conservation,current efficiency is high.This paper studied the electrodeposition coating of trivalent chromium from the copper sulfate in the system of sulfate and the experimental insta-llation of double-membrane and electrodeposited on the copper was first used. Bright,uniform and dense Cr coating was achieved by use of the technology, meanwhile,it got much characteristics,such as high current efficiency,good equality ability and depth ability,wide current density,simple equipment,and pollution-free characteristics.This paper explored the electrolysis system first, in Cr³⁺+(NH₄)₂SO₄ + H₃BO₃ system,by observing the quality of the coating, current efficiency,surface morphology,identified plating a bright,smooth, uniform,dense coating of solid,the optimum conditions is the Cr³⁺concentra-tion of 20 g / L,the current density Dk = 8～14A/dm2,pH= 2.1～2.5,the temperature is 26 to 34℃,electroplating time is about 15 to 20 min,conduc-tive salt(NH₄)₂SO₄.The process of trivalent chromium was studied through experiments and the effective factors such as current efficiency,temperature, pH value,electroplating process on trivalent chromium forming law was also discussed.Coating,plating solution and the performance of a more comprehe-nsive were all tested.With different additives,by adding a certain amount of OP-10,the current efficiency was high,followed by urea and saccharin.The experimental results showed that,in the three trivalent chromium sulfate system,bright,uniform,dense chrome plating can be gained on copper plating and OP-10 should be used as additives and the coating will be more uniform, bright,dense.On the contrary,saccharin as additive there was no coating and urea-although,very thick coating was got,but was a very serious skin,black surface.Through polarization curves,it can be seen that under the same conditions, stirring enabled the polarization curves move to negative,potential increased and the cathode polarization increased,which were conducive to precipitation chromium coating.With temperature increasing,polarization became smaller, which was not good for chrome;with the pH value increasing,polarization curve was moved to the correctitude.When pH value of 1.8 to 2.4 within the scope of the changes,it did not affect the polarization curves Obviously.The separating of chromium is conducive when the OP-10 concentration was 0.5 mol / L,which also caused the maximum polarization.