How to electrodeposit Aluminum (electroplating aluminum onto something)

A. Hi Matteo,

We added your posting to this long thread which discusses the ways of putting an aluminum coating onto an object. But remember that anodizing *consumes* aluminum in the process of making aluminum oxide from it.

And anodizing requires a certain thickness to be of value depending on what you intend to do with the components ... so methods which apply only a very thin coating of aluminum are probably not of value to you. Please tell us what you want to apply an anodized aluminum coating to and why. Thanks!

Luck & Regards,


Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

A. Hi again, Matteo.

If you are looking for a European supplier, I understand that there is or was an HGA Galvano-Aluminium of The Netherlands offering this process as well.

Luck & Regards,


Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

A. Hi Matteo, There is (or was) a company in Germany called Rasant-Alcotec Beschichtungstechnik GmbH near Cologne, which offered electrochemical deposition of aluminium. HGA withdrew from the business in the mid-1980s. I was head of the R&D team at Aluminal, a company that offered this technology on an industrial scale until 2008, and tried to do the same thing. The problem was to get an absolutely perfect aluminium surface without pores, because every pore causes problems during anodising.

A. Hello Kawhi. If you mean conventional aqueous-based electroplating, no, aluminum cannot be electrodeposited from conventional water-based electroplating baths. If you are asking whether it is possible --at all-- to apply aluminum onto aluminum, yes. IVD, cladding, and organic-based electroplating can be done.

Luck & Regards,


Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

A. There is a company that is electroplating aluminum, but I don't know if they can plate it on aluminum. I would suggest you look at Ion Vapor Deposition (IVD) of aluminum instead. You can probably find a company near you that can do the job.

A. To my knowledge there is one (count 'em) shop in the country that commercially electrodeposits aluminum, but it involves non-aqueous electrolytes and sealing out air from the process -- so this is not something that you casually just up and do.

As Jim says, aluminum is usually deposited by IVD, and in fact it's a common practice to deposit pure aluminum onto lower purity alloys by IVD.

A. Mr. Feger - IVD is not the only option to get an aluminum coating. There are many processes to "aluminize":

The method used to achieve an aluminum coating will depend on what your component is (i.e., cladding is typically used in the aerospace industry for large sheets), and what your specifications are for the layer, etc.

The company you are looking for is us (not the only company in the world, but one of only a couple).

A. Hi Brandon and Reynaldo. Aluminum cannot be electroplated out of a conventional aqueous plating bath because it is too active a metal, so all of the electricity goes to electrolyzing hydrogen out of the water instead of depositing aluminum. But it is not impossible to electroplate aluminum; rather it is a specialized process which must be done out of molten salts or special organic solvents. It may also be possible to electroplate aluminum via the rapidly developing field of ionic liquids, although as of this writing ionic liquids are not used in plating shops to my knowledge.

Alternately, aluminum can be deposited by a vacuum process (vacuum metallizing) or by Ivadizing, and as Reynaldo mentions by flame spraying. Every process has limitations: some are line-of-sight only, some are limited by chamber size, etc. Consequently, you must specify in some detail exactly what you are trying to do (production rate, part size and shape, how thick the aluminum should be) before people will be able to best help you. Good luck.

A. Hi,

I don't know if this helps, but I have also been interested in plating steel with aluminum. I was recently contacted by a gentlemen from Alumiplate, who was very helpful. You may wish to check out their site.

Good Luck,

A. Hi. There is a Siemens Sigal® process for electroplating aluminum, which is based on an alkyl aluminum fluoride in toluene and operates at 100 °C, which might be similar to what Alumiplate does; there is also molten salt plating, CVD plating, maybe other processes -- but 'conventional' electroplating from aqueous solutions is not possible because aluminum is too active.

Luck & Regards,

A. Kapila:

There is no common knowledge of electrolytic plating of aluminum at low temperature. But there is a conventional Al vacuum coating used extensively on all kinds of plastics.

Dear Mr. Oliveira,

A. It is indeed possible to plate products with aluminium, though not out of a conventional (aqueous) plating bath. Aluminium can be deposited from organic solutions. I know that a German company has a process which deposits aluminium on products.

A. Alumiplate is another brand name for plating products with aluminum.

A. Mr. Oliviera,

We can plate 300 series stainless steel with a high purity Al coating. Although the coating itself could not survive up to 1000 °C, I assume you would want to anodize it. Let me know what questions you have. We have several customers that routinely anodize the coating for their applications.

Regards,

A. It is possible to plate Aluminium, the only solution for this which has been commercially realised is the Sigal process , which has been invented in 1973. It uses Toluol as solvent, the problems with it are: it has to be absolutely water-free, you need an inert-gas atmosphere over your electrolyte, and the electrolyte is decomposing over time due to its instability.
This makes the process very expensive; to my knowledge there are only 3 or 4 companies in the world working with it. If the workpieces you want to be aluminium coated are not sensitive to heat, a PVD coating will be much cheaper.

A. This is one where you will have to go back to the customer and ask what the alternatives are.

I would be surprised if you could just drop the Aluminium coating, especially as this is going to affect the dimensions of the part.

You don't mention whether this is a Type I or Type II coating (although for use in a marine environment one may expect it to be Type I because of the potential environmental damage of the hexavalent chrome).

Directly replacing Aluminium with chromate conversion means that you lose the thickness of the aluminium coating and so risk corrosion of the component at a much earlier stage,

For treatment of titanium the same really applies, that is, ask your customer.

A. Hi Metin. MIL-DTL-83488 says the coating can be applied by IVD, sputtering, or the special organic electroplating methods of Sieman or Alumiplate, or any other method that works. But in addition to what Brian has mentioned, the general idea behind this spec is that the high purity aluminum it calls for has greater corrosion resistance than the substrate materials you mention.

Luck & Regards,

A. Aluminum cannot be deposited from solution containing water because of the reason Ken mentions. I am working on depositing aluminum from non aqueous solution at room temperature currently. You may find US patent number 6,083,647 filed by Takahashi et al. interesting.
Q. I also had a question about aluminum. Does anyone know of a chemical/ chemical mixture which will dissolve alumina but not aluminum?

Thank you,

Meenakshi Singh
- State College, Pennsylvania, USA
January 24, 2008

A. Thanks, Meenakshi. Alumina can be dissolved without attacking aluminum with a mixture of chromic and phosphoric acid. If you search the site for "strip anodized coatings" you will see a number of references to it including topic 3397. Good luck.

A. Hi, Bidyut.

There are probably a number of solvents that can theoretically be used.

"Studies on the AlCl3/dimethylsulfone (DMSO2) electrolytes for the aluminum deposition processes" by Jiang, Chollier Brym, Dubé, Lasia, and Brisard, (Surface and Coatings Technology, Volume 201, Issue 14, 2 April 2007, Pages 6309-6317)
suggests that AlCl3/dimethylsulfone (DMSO2) is a promising possibility. You can order a copy of the paper from www.sciencedirect.com/science/article/pii/S0257897206014484

But the previously mentioned Alumiplate is a commercial concern which electroplates aluminum out of an organic solution; naturally, they retain much of their knowledge of the topic as proprietary trade secret.

Good luck.

Regards,

A. The only way I know of is to use ionic liquids and this is not commercial. You may be able to use PVD or sputtering technologies, but I do not know of it on a commercial basis

A. There is a vendor of aluminum plating process in the USA in MN (Alumiplate). But it is very expensive to buy and to operate, so it has limited commercial applications. In short, it is not practical for most applications.

You can coat parts by PVD deposition. Ivadizer is an old name for one of the processes.

A. I have been coating aluminum by cathodic arc process on various substrates. Adhesion is pretty good. We can coat aluminum on copper also!

A. Many companies claim that aluminum can be electroplated using Ionic Liquids based solutions.
Ionic liquids is the next generation & water free electroplating technology .
You can find more information in the following link:
http://www.basionics.com/en/ionic-liquids/applications/metal/aluminum-plating.htm
This technology is still under development; materials may be degraded under air atmosphere .
Anyway it is recommended to follow up this new technology

A. You can vacuum evaporate aluminum onto nickel, or, if you need a denser coating, sputter deposit the aluminum.

A. Hello Iqbal!

When I want to coat with aluminum, I'll first use an ion vapor deposited technique: AMS2427 and MIL-DTL-83488 are two specifications that cover the process.

If I need a better, denser, more corrosion resistant or higher adhesive strength coating and I'm willing to throw more money at the problem, then I'll use the organic solvent electroplating process mentioned above. AlumiPlate is one company that does that process.

A. Hi Robin. The subchapter you quote from ASM Metals Handbook, Vol. 5 is indeed about electroplating ONTO aluminum, and it does not seem to offer anything on ELECTRODEPOSITION OF aluminum. Each half of the proposition has its quirks because:
1). Electroplating of anything onto aluminum presents difficulties because of the instantaneous formation of aluminum oxides on the aluminum substrate. The most common solution is an immersion deposit of zincate, followed by electroless (autocatalytic) nickel plating, followed by whatever type of plating you seek for the top layer. The handbook addresses this half of the problem well.
2). Electrodeposition of aluminum is difficult because you cannot use aqueous baths -- the applied electricity hydrolyzes the water into hydrogen gas and hydroxide ion instead of depositing aluminum. You are limited to plating from fused salts or the previously mentioned patented organic solution.

While we perhaps could find some stuff about electrodeposition of aluminum for you, it might be such a large research project as to derail you from your present goal. I would suggest that consider simply contracting out the IVD coating of your samples to a jobshop. I'm quite sure that IVD is the best solution to the problem you have presented. Good luck.

Regards,

Ok, good! So I will follow your advice with the IVD coating.

Thank you very much for responding ;)

A. IVD is ok, but the coating will have an open structure, and is usually relatively thick. Given that this is an experiment, and you have small samples, suggest you look into sputtering. Sputtered aluminum will be much denser, and it will be easier to find someone in a university that will coat the samples for you. I know they have suitable equipment at the University of Illinois, Colorado School of Mines, UCLA, and Michigan, to name a few sites. You can also check with your local chapter of the American Vacuum Society.

Thanks Jim. I gratefully yield to your knowledge of vacuum coating processes.

Regards,

A. Hi Smarajeet. Unfortunately there is probably no solution to your immediate situation because aluminum cannot currently be electrodeposited from AlCl3 in an aqueous solution. We appended your inquiry to a thread which explains why and what the options are.

Regards,

A. We have developed a solution to this problem using organic ligands to stabilize the Al center in such a way that the reduction potential is decreased to less than water. Thus allowing us to electrodeposit Al from aqueous media.

Best Regards,

A. Hi Dale. Please give us the URL of that video. It isn't possible to electrodeposit aluminum with any conventional electroplating process, as you'll read here.

Luck & Regards,

Looks like I wasted some of your time, Ted. Looking most of the day and can not find it. Must have been half asleep. May had been watching Zinc plating. Close, but no cigar. Sorry. The amount of great info here has helped me so much, big thanks too all.

A. Zinc plating has a long history of pretending to be aluminum plating, Dale. In the 1990's I was involved in the replating of the ironwork/clock tower of Philadelphia's City Hall/Wm Penn Clock Tower which, when it was built in the 1890's, was claimed to be plated with aluminum ... but it was actually zinc plating of course.

Luck & Regards,

Well Ted, I re-watched the video and he did admit you can not deposit Al directly onto Al. But only after he was burned on the comments. He then had to admit it was a zincate solution. Had a laugh though. As a hobbyist I'll try whatever looks the best way here, which is a goldmine of great info. Thank you for getting me on the right track. very helpful when your a 1st timer to this process. Having a hoot learning this stuff.

A. Hi Siemen. Electrodeposition of aluminum is possible (but not from aqueous solutions). Ironically it's often called "The Siemens Process". But it is very specialized, and electroplating is not generally good for thick layers.

Luck & Regards,

A. Alumiplate the company can plate onto aluminum. Let me know if you have any questions. I would be happy to answer them.

"Electrodeposition of Alloys: Principles & Practice"
by Abner Brenner

on AbeBooks

or eBay or

Amazon

(affil links)

A. Hi Siemen. Electrodepositing an alloy is generally much more difficult than plating a pure metal, and only a few alloys are routinely electrodeposited, although Abner Brenner has written a 1400-page tome on the subject :-)

The reason it is so much more difficult is that there are no ions of alloys, there are only ions of the individual metals, so what you are trying to do is to get two or more different ions to electrodeposit but each has it's own deposition potential. The more noble metal, the one with the lower potential, will deposit readily and the baser metal will not deposit at all. In general, "tricks" are required for alloy plating like complexing/sequestering the more noble metal.

Carbon-zinc battery electrolyte is zinc chloride in water according to Eveready, so you still have the problem that hydrogen rather than aluminum will be reduced at the cathode.

Luck & Regards,