1) Problems in electrode paste electroplating
① Nickel ion in solution rises too fast. Due to the high chloride ion content in the solution, which is twice as large as that in the high nickel tank, the nickel anode dissolves too fast, which brings difficulties and troubles to the normal maintenance of the tank solution.
② The pH value of the plating bath rises very fast. Sometimes LH needs to be adjusted several times, causing more failures.
(2) Adoption of graphite anode
Anode material area ratio: nickel: iron: Graphite = (11.5 ~ 12):1:1.
If the graphite area is too long, it is easy to reduce the main salt concentration and pH value in the solution; If it is too small, the effect is not obvious. Through practice, it is necessary to obtain an ideal area ratio, which not only controls the concentration of plating solution components and the proportion of plating alloy, but also does not make the pH value of plating solution too high or low, which depends on the difference of cathode plated area .
(3) Working principle of graphite anode
① The graphite anode discharges 0h- on the anode graphite, releasing oxygen 02 and water. The reaction formula is as follows: 40h-=02 ↑ +2h2o+4e
And water molecules are continuously ionized to provide oh-:2h20 → 2h++20h-
Based on the above two formulas, graphite consumes a large amount of oh-, and continuously replenishes h+ to the plating solution, so as to provide h+ consumed by hydrogen precipitation from the cathode, so as to achieve the stability of pH value of the solution.
② The current consumed by graphite is only to release oxygen, instead of dissolving nickel and iron ions into the solution like nickel and iron plates, thus reducing the current flowing to nickel and iron plates, thus reducing the excessive growth of nickel and iron ions in the solution. Adjusting the area of graphite also regulates the distribution of current, so that the supplement of ions and iron ions can appropriately supplement their consumption, so as to achieve a stable concentration of nickel and iron main salts.
(4) Usage of graphite anode
① Graphite hanging graphite is brittle, easy to break and free from impact, * put it into titanium basket or protective basket, and hang it on the anode with titanium hook.
② Graphite surface treatment use a woodworking plane to smooth the rough surface before use.
③ Graphite wrapping should be covered with multi-layer filter paper and then covered with polyester cloth