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Electroplating with copper?

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LAN_403

Firnagzen

Sun Jun 01 2008, 01:44AM

Registered Member #567 Joined: Tue Mar 06 2007, 10:55AM
Location: Singapore
Posts: 147

Story part:
I've just obtained a nice shiny new butane powered blowtorch/soldering iron. But I'm a bit worried about the tip being eroded away and not taking solder any more, and I can't get tips for the iron so easily. So I was wondering when that day occurs (ie. unusable tip), I can replate the tip with copper?

Science part:
Well, to do that, I need a solution of copper salts. Unfortunately, I live in Singapore, so there aren't any good sources of chemicals around that I know of, so it looks like I'll have to make some myself. Does anyone on this forum know how? (I can get copper metal with no problem, though.)

Firefox

Sun Jun 01 2008, 04:18AM

Registered Member #1389 Joined: Thu Mar 13 2008, 12:50AM
Location: Pittsburgh, PA
Posts: 346

I know you could do a redox reaction with FeCl3+Cu-->FeCl2+CuCl to FeCl3+CuCl-->FeCl2+CuCl2. I don't know if this reaction will work, seeing as it would likely be difficult to separate the two products, and I also don't know how well you could electroplate it, but I thought it may help a bit.

Shaun

Sun Jun 01 2008, 06:04AM

Registered Member #690 Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616

If you set up an electrolyser with a salt bridge, you could use a copper anode and any cathode. If you let this run for a very long time, you would eventually end up with all CuCl2 on th anode side and all NaOH on the cathode side.

The downside is that no salt bridge is perfect and you will never get *all* the Na+ to one side. You can get very close, though. I've done this with a KNO3 solution (not for electroplating, just to make copper nitrate). It was run off an MOT rewound for 15V and would push nearly 10A through the solution. My salt bridge was made of 1" PVC pipe with cotton plugs in each end.

As a test, I put some solution from the anode side in its own electrolysis cell (graphite anode, no salt bridge). Only a very small amount of H2 was generated (>10 bubbles per minute), and a large amount of black copper dust. Pure copper nitrate would yield no H2 and all copper dust.

The reason you want a very small amount of Na+ (or K+ in my case), is because when you go to do the actual electroplating the cation impurities will form OH- at the cathode (workpiece), which will precipitate out along with some of you precious Cu+2.

One last note, no matter how you get your copper solution, when you get to the actual electroplating, you will have to do so *very* slowly. You will have to use very low current, especially since you will have a very small workpiece. If you go to fast, the copper metal will just fall off as a black dust. The maximum current to use while still avoiding this is something you will have to experiment with.

Wolfram

Sun Jun 01 2008, 07:13AM

Registered Member #33 Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971

The chemistry behind copper plating is all well and good, but of no relevance with this problem. Soldering tips are usually made of a solid copper core that is iron plated. To do what you want, you need to iron-plate the tip. Here's a thread with some relevant info:

Shaun

Sun Jun 01 2008, 02:20PM

Registered Member #690 Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616

Wouldn't copper still work, though? I mean solder obviously bonds extremely well to copper, in fact its almost like it's designed to. I always though the tips were actually tinned copper, but I guess they're iron. Either way, for the majority of the life of the tip, the iron plating has worn away and for all intents and purposes we are soldering with a copper tip.

Firnagzen

Mon Jun 02 2008, 02:31AM

Registered Member #567 Joined: Tue Mar 06 2007, 10:55AM
Location: Singapore
Posts: 147

Thanks for all the responses and help. So, I get some copper wool, use that as the anode, put in in one beaker, use a salt bridge to another beaker with the cathode in it, and zap it with a PC power supply? The solution in this case is concentrated NaCl, right?

Also, Shaun (funnily enough, that's my name, too), that's exactly what I was thinking, too. Weird.

Incidentally, wikipedia says:

Modern soldering iron tips are usually iron coated to reduce the need for resurfacing. When a tip is pitted, it is either replaced or filed to give a fresh clean surface. A copper faced tip pits a little quicker than an iron coated one, but does not present any usability issues. Molten solder should be wiped off before filing.

Bare copper tips that are repeatedly resurfaced, as typically found on old high power irons, can last decades in use, and the shaft of the copper tip is prone to corrosion over such long times. It is therefore best practice to remove and wire-brush the bit to remove shaft corrosion about once a decade, to maintain effective thermal contact with the iron.

EDIT: Erm. I've left the setup running for a while now, and the anode side solution is becoming extremely murky while the cathode side solution is clear, but there are lots of bubbles appearing on the cathode. Shaun, is this more or less right? Thanks.

Hon1nbo

Sat Jun 14 2008, 01:01AM

Registered Member #902 Joined: Sun Jul 15 2007, 08:17PM
Location: Pacific Northwest USA
Posts: 1042

I tought myself copper plating on accident with this [note: this uses a relatively safe, but still dangerous acid; it can be used safely but take appropriate caution, this is what worked for me]
get a piece of copper that has some green oxidation on it (like the statue of liberty, you just need a little piece of green to get started, as the process produces more) then take it and some CLEAN copper and place it in a [about] gallon bath of hardware store muriatic acid and let it sit for a while [until the solution turns blue, or two hours later, but the time is best] then neutralize the solution with some sodium bicarbonate (baking soda) and keep doing so until no bubbles form (POUR IN ONLY A LITTLE AT A TIME, OR YOU CAN MAKE THE ACID SPLASH!)
the blue liquid is CuCl2, and will directly plate some metals without electricity (though it never hurts, I recommend 8 AAs with a piece of copper as the anode and the tip as the cathode)
this works well when I use it.

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