Boric acid in nickel plating solution in what role, if boric acid deficiency, what will happen?

A: Boric acid nickel plating solution is a buffer to buffer the pH of the bath effect. When the concentration of 31 g / l or more, have a significant effect, but not too high, because the solubility of boric acid at room temperature, about 40 grams / liters. As boric acid buffer, the pH value of the cathode region will not produce radical changes, which can allow the use of higher cathodic current density on the cathode without hydroxide precipitation. It also has to improve and improve the coating properties of cathodic polarization effect. But its content is too high will reduce the cathode current efficiency. Less than 20 g / l buffer weak, leaving the bath pH value increased, affecting the quality of the plating layer, the plating process can not be even.
37 nickel, the pH of the electrolyte near the anode and the cathode that close to a pH of the electrolyte is high, and why?
A: Yes, the pH of the electrolyte near the cathode is high. This is due to the electrolysis process, the hydrogen gas leaving the cathode is deposited on the pH rises. 2H + +3 → H2 ↑
38 galvanized after passivation film, white and color passivation passivation layer that kind of good corrosion resistance?
A: galvanized after passivation film, color than white passivation passivation good corrosion resistance. This is because the treatment for blunt white is the color of the passivation film has been formed in the bleaching solution, dissolve treated layer, a passivation film of the color white. Since the white color passivation layer over the passivation layer is thin, the corrosion resistance can be reduced.
39 treated with barium carbonate chrome excess sulfuric acid solution, one gram how many grams of barium sulfate that?
A: To remove one gram of sulfuric acid, in theory require about 2 grams of barium carbonate.
40. Freshly prepared pure chromic acid solution Why not chrome plated to? Why should electrolysis treatment or after a bath in order to add some old-plated coating of good quality?
A: The new preparation of pure chromic acid solution, if there is no trivalent chromium and catalytic anion, is not easily connected to the cathode of the electrolytic reduction of chromate reduction of hexavalent chromium to trivalent chromium ion is not, nor reduced to chromium . The result is equivalent to the electrolytic decomposition of water to generate hydrogen gas at the cathode 2H + +2 e → H2 ↑, to produce oxygen on the anode 4OH - 4e → 2H2O + O2 ↑. So no chrome plating to. When sulfuric acid was added, the solution in which the trivalent chromium complex with a positive charge generated in chromium sulfate [Cr4O (SO4) (H2O) 4] 2 +, due to the sulfate ion radius is small, the charge is high, it easily with The positively charged adsorption chromium sulfate, colloidal Molybdenum tube through basic chromium chromate, Cr ions can promote the precipitation of chromium cathode discharge. Chrome freshly prepared solution, the absence of trivalent chromium, chromium plating is not easy, and therefore need to be processed to produce electrolysis trivalent chromium. Add some old bath is intended to keep the bath contains a certain amount of trivalent chromium in order to facilitate the precipitation of metals.