Why control the nickel ion concentration of the cathode liquid?
The precipitation potential of cathode nickel is related to the concentration of nickel ions in the solution. In order to obtain high purity electrical productNickelProducts, there are certain requirements for nickel ion concentration in production.NickelIon concentration is too low, will promote cathode hydrogen precipitation, so that the cathode region of local ph rise, the formation of Ni (OH) z precipitation, affecting product quality. Nickel ion concentration is too high,NickelPlate grain roughness, surface easy to form bumps, of course, nickel ion concentration is too high is not economical.
In order to ensure product quality, according to different nickel ion concentration flexibly adjust the electrodeposition production current, so that it reaches a reasonable balance point, to avoid high current control, low nickel ions or low current, nickel ions caused by the electro-nickel surface long gas lone l or granulation affect product quality. Through long-term production practice, reference table 9-2 nickel ion concentration control in the process of current adjustment.
In the production process should be strictly controlled according to technical conditions, to avoid the current and the main metal concentration control mismatch, affecting product quality. (2) A clean diaphragm bag must be cushioned. (3) It is strictly forbidden to tread on the starting pole tablet with both feet. (4) Make sure that the original angle and plate surface of the rear pole after the plate are straight. Press on when the tablet is operated strictly
The operation is required to avoid two pollution on the surface of the starting pole and to ensure the cleanliness of the surface. 517. What is the effect of cathode ph on the quality of electrodeposition nickel?
Although harmful impurity ions in nickel saline solution electrolytes can be removed as far as possible by chemical methods, the hydrogen ions in them are always present. This inevitably complicates the cathode process of nickel electrolysis. Calculations indicate that at 25QC:
EH2/H+=-0.0591pH (9-19) ENVNi2+=-0.25 +0.02951gcwi2+ (9-20) when the cn,:+ is certain, then E. ，。 ,: + constant, while E. ：，。 + Changes with ph, when ph is low, then E. ：，。 +>e. ，。 , +, so that hydrogen takes precedence over nickel in cathode precipitation, electrodeposition nickel surface to form a large number of stomata, when the ph is high, will produce Ni (OH) 2 precipitation, so can not get dense cathode nickel. The control range of the ph can be found in the e-ph diagram of the NI-H20 system.
Therefore, the cathode liquid ph must be strictly controlled within the technical conditions, the production of general control ph 3.0~3.8.