Electrodeposition of Bismuth, Bismuth Plating Baths

A. You might want a copy of Dingley, et al, Plating and Surface Finishing 63(4), 26, 1978 for a review of bismuth plating, as bismuth plating is not a commercial process.
Lowenheim's ("Electroplating" ⇦[this on eBay , Amazon, AbeBooks affil links] ) mentions that Bi plating might have "some minor uses in the electronics and nuclear energy fields".

A. Compared to say Nickel, not much is written about Bismuth. The anions are: perchlorates, chlorides, and (alkaline based) tartrates. All of the major plating books have something on plating the uncommon metals. Try Modern Electroplating by Lowenheim [on AbeBooks, eBay, or Amazon affil links] .

Regards,

Dear Sir,

I have recently read your letter regarding information on plating Bismuth. We have developed an aqueous solution which will deposit Bismuth onto a magnesium base metal. This is a selective, electrolytic process that has so far shown good results.

"Modern Electroplating"
by F.A. Lowenheim

on AbeBooks

or eBay

or Amazon

(affil links)

A. It would take a book to answer your question.

A good place to start would be Modern Electroplating by Lowenheim published by Wiley.

Reducing agents serve no purpose in normal electroplating solutions and why do you think sodium sulphate is a reducer?

Very few metals deposit from simple ionic salts and I can think of none that plate from a nitrate bath which I would expect to give off ammonia ⇦this on eBay or Amazon [affil links] from the anode.

There are few practical applications for bismuth plating so finding a practical process may not be simple.

Have you considered PVD as a practical alternative?

A. Hi Edwin

It might help if we knew what you want your deposit to do.

If you need a functional deposit, developing a viable plating bath is not a simple solution. Professionals expect to spend months in development with considerable lab backup. Well, I did, but you could get lucky.

On the other hand with a MP of 271° C, bismuth should be a simple job for PVD and easy to set up in a lab. You need a small vacuum chamber and a twisted tungsten wire filament that can be heated to red heat by a small power supply. Load scraps of Bi onto the wire and heat gently under vacuum until they melt and coat the filament and then increase the heat to evaporate. Take it gently or the Bi will fall off! The next step up is a W or Mo boat but you should not need sputtering equipment.

Even simpler, if someone in the lab has a SEM, they probably have a coater you could use for a trial. (a promise of beer may improve their generosity)

"Electroplating Engineering Handbook"
by Larry Durney

on AbeBooks

or eBay or

Amazon

(affil links)

A. Hello,
The question needs to be answered with Electrochemistry basics and applied electrochemistry, i.e., electroplating knowledge. Books like Electroplating by Lowenheim ⇦[this on eBay , Amazon, AbeBooks affil links] , Electroplating and Engineering Handbook by Kenneth Graham.

Electrochemistry by E.C.Potter etc must be gone through. Otherwise it will be like going in wilderness. For e.g. you incorporate a nitrate solution with nitric acid, NO3-ions will get reduced at the expense of metal deposition at the cathode! A very high concentration of metal ions means a very high nucleation rate and you will end up with a non-adherent deposit.For e.g., electrolysis of Silver nitrate solution will only produce non-adherent treeing!Sulphates will be a better selection as electrolyte. Solubility of the salt is an important consideration.Adding electrolytes to improve conductivity of the bath and additives generally organic compounds for better deposit qualities like brightness, etc. are to be investigated.Throwing power and cathode efficiency needs study. A literature survey for a decade (see chemical abstracts) will give a proper leads for further experimentation.

A. Bismuth is used as a substitute for lead in some solders and can be electrodeposited. It is, however, not a common process.

Lowenheim in "Modern Electroplating" [on AbeBooks, eBay, or Amazon affil links] suggested a bath of 40 g/l Bi2O3 with 104 g/l HClO4 and glue and cresol as additives. This is rather nasty as perchloric acid is prone to cause explosions. There is also a recommendation for NaBiCl4 with excess hydrochloric acid, but he concludes the perchloric acid bath is better for electroplating.

More recently a patent was granted for the use of bismuth chloride with various chelating agents; one such bath is 200 g/l potassium pyrophosphate, 35 g/l bismuth chloride and 10 g/l dextrin. The pH is adjusted with either HCl or NaOH, as required. Variations on this include the use of EDTA, with or without pyrophosphate, and gluconic acid as chelators. These baths can be: 1) EDTA 100-250 g/l; NiCl2.H2O 10-100 g/l; dextrin 1-50 g/l; pH 9-11; 2) 50% gluconic acid 100-300 g/l; NiCl2.H2O 10-140 g/l; EDTA 50-250 g/l;' dextrin 1-50 g/l; pH ~10, adjusted with HCl; 3) Potassium pyrophosphate 200 g/l; EDTA 150 g/l; NiCl2.H2O 48 g/l; dextrin 10 g/l pH 9-10. All these baths can be used either hot or at room temperature; if hot the ccd can be at least 50 ASF, but the colder bath prefers 25 ASF.

Bismuth can also be deposited by an electroless route. One prescription is: Bi salt 5-20 g/l; HCl 50-500 ml/l; Iodide 0-4 g/l; wetter <1 g/l; pH<1 temp 150±10 F. This uses an immersion time of 30 secs to 5 mins. Alternatively, dissolve 5g of Bi2O3 in 200 ml of HCl (conc.) and stir for 1 hour at 100 C. Add 100 g of 70% glycolic acid, with 100 g of N methyl pyralidone and 100 g monoethanolamaine. This is followed by 1 g potassium iodide. Dilute to 1 liter.

A. Hello Carlton,

Bismuth can also be brush electroplated. We currently have a bismuth brush plating solution that was originally designed to plate onto magnesium alloys. The bismuth solution, like most brush plating solutions, has a different chemistry than conventional tank plating solutions.

A. First of all, at what potentials are you trying to deposit bismuth onto titanium? What else does your solution consist of other than DMSO and bismuth nitrate? Titanium has a negative Redox potential, so it could be that you are oxidizing the titanium. I would guess though that you need to go to higher reduction potentials because there may be a large overpotential for the reduction of bismuth on titanium. Also, bismuth is very chemically sensitive so any etches that remove titanium are likely to remove bismuth as well.

Hi Jason. Yes, aluminum instantly forms a passive oxide layer, so it requires a special preparation cycle which usually involves immersion zincating followed by cyanide copper electroplating or electroless nickel plating before your final plating layer(s). Good luck.

Regards,