Material Choice for Anodes & Auxiliary Anodes in Nickel Plating?

A. Hello, Aon. (Sorry, we deleted the name of the plating shop you mentioned; they may consider it a trade secret and inappropriate for us to tell the world what they use for auxiliary anodes). A number of shops use platinized titanium auxiliary anodes, and I don't think it's a problem. I personally don't think the platinized anodes are the source of the shelf roughness.

A. Aon,
Just a quick note to add. If you suspect the Pt is peeling from the Ti substrate, take a portable propane torch and heat the anode for one minute, keeping the flame in one spot. If the anode turns black after wiping away any smut, there is very little or no platinum on the surface. If it remains a silver grey color you have sufficient Pt thickness. I prefer platinum "clad" Ti or niobium. The term "platinized" can mean the anode material is electroplated with as low as 10 microinches Pt thickness. Does your anode supplier provide certs regarding material type, lot # and thicknesses? It is important to know.

A. I am in perfect agreement with Ted Mooney, but want to add a couple "way-out" possibilities.

With high voltage in the presence of chloride, the platinum will be undercut and fall off, but probably would not settle on the shelves.

If the boric acid is too high for the temperature, then the boric acid will fall out on the shelves, and this is a very common cause of shelf roughness.

A. Nont,
Did you platinize the titanium after fabrication? Maybe there are welds that are not platinized?

Thank you so much for your ideas.

Q. How can I measure platinum thickness? Can I use Ir/Ti mesh or Ru-Ir/Ti mesh to be auxiliary anode in nickel or acid copper bath? Is it source of any problems if I use it?

Is there any devices or tools that can do this work? Where can I buy it from?

Thank you for taking time with my question.

A. Hello Nont D. I am working for a company which produces titanium anodes. You can use Ir/Ti mesh or Ru-Ir/Ti mesh to be auxiliary anode in nickel or acid copper bath. But if you use Ir-Ta/Ti mesh, the life of the anode will be longer, and electrolytic effect will be better. About the platinum thickness, there is no device or tool can do this work in our country. You can turn to some other countries.

A. Hi James. For an electroplating process to take place, metal must deposit on the cathode. This metal can come from either one of two places: it can come from consumable (soluble) anodes made of the material that you are trying to plate; or it can be dissolved into the make-up solution, in which case you use non-consumable or DSA anodes whose purpose is to act as an electrode not as the supply of metal.

It is usually best to use consumable anodes because they will be an inexpensive source of the metal, and it's usually easier to keep the solution in balance because metal is dissolving into it in almost exact measure to the metal being plated out of it. But there are cases where consumable anodes cannot work for electrochemical reasons (chrome plating, for example), or where they would be prohibitively expensive (no one can afford to have hundreds of pounds of gold anodes sitting in a gold plating tank), or where a combination is best (the nickel plating step in chrome plated wheels, where soluble consumable anodes supply the nickel but DSA auxiliary anodes may be used to get an electrode deep into recessed areas).

DSA anodes can be platinum clad titanium, but there are several other choices discussed above.

A. Hi, John.

As far as I can envision there would rarely be a need for auxiliary anodes to dissolve, so I don't see why Nickel 200 could not be used for the auxiliary anodes. But I think you will need depolarized nickel for your main anodes in order to reliably dissolve nickel into your bath for the plating to reliably continue. If you can't obtain it as oval bars anymore, I think you'll need to switch to anode baskets and S-rounds or similar. Good luck, and maybe you'll get a more encouraging second opinion.

Regards,

A. Nickel 200 is 99% nickel, so it would not be a bad metal to uses as an auxiliary anode if the total area was a fairly small % of the total anode area. Since it is not very soluble compared to S rounds, it is going to affect the internal stress of your nickel plate. We used it to keep the internal stress in the desired range as well as it filled a need on certain parts. Excessive use is as bad as not enough.
You could use micromesh Ti baskets with SD nickel pellets. I used them in a 1" dia. basket, covered with napped poly "socks".

A. Hello Sherrill,
You may have better luck finding titanium rods or platinum clad titanium for your auxiliary anodes. I would not use SS anodes. One thing to keep in mind is that good cathode agitation that will "push" solution into the holes, thereby supplying fresh Ni ions inside the holes at a good rate. Front to back cathode rocker agitation works well in conjunction with eductors on your filter system discharge lines. Good Luck!

A. Are you plating other portions of the part at the same time? If so, you would have better plating if you used a second power supply for the Aux. anode since your anode to cathode distance will be much tighter.
Very good air agitation under the bores will go a long way to getting uniform plating.

A. Greetings,
The main reason that Au anodes are not used is because of the theft risk factor. As you know Pt anodes have very low resistance qualities. With most Au solutions, current efficiency runs between 40 and 50%, so it makes more sense to use Pt. In acid or neutral gold plating, Pt anodes are the norm in the industry.