Variation of Cathodic rust prevention

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vinceat852
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Variation of Cathodic rust prevention

Postby vinceat852 » Mon Jun 13, 2011 7:29 am UTC

So here's the thing: I'm going to start a fencing club at school next year and I need to stop my electric lamés (jackets) and masks from oxidizing, because the budget's so tight that we'll have to share the lamés come competition day as it stands.

so here's my diagram for my idea:
Image

I was wondering if it would work...
(I don't want to actually have to construct an experiment with (not) controlled environment at home over the summer to try)

thanks!

edit:
I hope that this won't waer out the battery any faster than would be required to replace electrons lost by the metal strip.

sikyon
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Re: Variation of Cathodic rust prevention

Postby sikyon » Tue Jun 14, 2011 6:44 am UTC

Can you elaborate abit more on exactly what you hope is going to happen?

vinceat852
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Re: Variation of Cathodic rust prevention

Postby vinceat852 » Tue Jun 14, 2011 9:08 am UTC

sikyon wrote:Can you elaborate abit more on exactly what you hope is going to happen?


Sure.

I was hoping to achieve two things:
1. to prevent my metal fencing jackets from rusting.
2. being able to do so without having to make use of an electrolyte or a constant current (ie, I won't have to replace the batteries too often)

The way I look at this is that the connection to the cathode of the battery would keep metal object from undergoing oxidization by supplying the electrons to it when it loses electrons to the natural environment. The grounded anode would take electrons from the earthed wire.

I'm not too sure whether or not it'll work because I'm trying to combine what I learnt in chem class (i'm only in high school) and in physics class. I'm trying to look at this like it's a giant capacitor.

thanks again!

stianhat
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Re: Variation of Cathodic rust prevention

Postby stianhat » Tue Jun 14, 2011 10:56 am UTC

vinceat852 wrote:
The way I look at this is that the connection to the cathode of the battery would keep metal object from undergoing oxidization by supplying the electrons to it when it loses electrons to the natural environment. The grounded anode would take electrons from the earthed wire.


Umm... You need to connect the "battery" to both the fencing shirts and the corrosive agent for this to work, it has to be a closed circuit which counteracts the corrosive circuit. Which means you have to have them covered in electrolyte, yes... Batteries are not, and can not be "electron donators". You could try a van der Graff device to keep them electrified tho ;)

Are the fencing shirts made with tiny chainmail or mesh thingies? That is really hell to protect, since the tiny openings and slits between chains are prime sites for corrosion.

The best thing is to keep 'em oiled or covered with some other rust protection.

Btw, how do they corrode? humid air?

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Velifer
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Re: Variation of Cathodic rust prevention

Postby Velifer » Tue Jun 14, 2011 1:05 pm UTC

vinceat852 wrote:I need to stop my electric lamés (jackets) and masks from oxidizing

They're stainless steel. The oxidation is a chromium oxide, a thin layer of which will still be conductive.
Rinse the sweat out of them, and heat dry.
Time flies like an arrow, fruit flies have nothing to lose but their chains -Marx

vinceat852
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Re: Variation of Cathodic rust prevention

Postby vinceat852 » Tue Jun 14, 2011 3:14 pm UTC

Velifer:
Velifer wrote:They're stainless steel. The oxidation is a chromium oxide, a thin layer of which will still be conductive.
Rinse the sweat out of them, and heat dry.

I wish. I've personally shelled out for a leon paul lamé, but the ones our school can afford would be ggg or jiang or some other made-in-china oxidizable ones. Before I got my beloved leon paul lamé, i used to have to change one every half a year or so. (Hong Kong summers = 80-100% Relative humidity, winters = 60-100% humidity.)
So we can't really leave them out to dry and the gym (where I'm assuming that we're going to store the stuff) does not have 24/7 air-conditioning. =_=||

stianhat:
yes, as I said in my reply to velifer above, hong kong's weather can be the devil.
and yes, fencing jackets are usually made of a mesh of wires.
so is there anyway that I can keep them oxide-free? sacrificial protection by attaching them via a wire to a block of zinc?
and no - I can't just put oil on them; I need them to conduct electricity.

and would it be possible to simply throw on some vinegar/weak acid and just corrode off the oxide then wash out the vinegar?

gorcee
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Re: Variation of Cathodic rust prevention

Postby gorcee » Tue Jun 14, 2011 6:35 pm UTC

Cathodic protection works because the object is immersed in electrolytes, and this allows for different potential fields than you'll get from atmospheric corrosion. I don't think that you'll see this effect in atmosphere. Cathodic protection works by connecting the material to the negative pole of a DC source. In essence, you're over-supplying electrons. This is a simplified description, and it doesn't fully prevent corrosion, but it does slow it down.

Anodic protection, which is what you're suggesting by use of a sacrificial anode, only works in materials that can passivate. Alternatively , if you have such a material, you can connect it to the positive pole of a DC source. However, this will almost certainly NOT work in atmosphere, as it requires a immersion in a material of high conductance, which atmosphere is not.

2.71828183
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Re: Variation of Cathodic rust prevention

Postby 2.71828183 » Tue Jun 14, 2011 6:52 pm UTC

You might try storing them in a closed container with desiccant. If you can find space in the budget for a good amount of silica gel (or another desiccant like calcium chloride, bearing in mind that that's corrosive if you let it contact the metal), then you should be able to store them in a non-humid atmosphere and avoid the problem in the first place.

stianhat
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Re: Variation of Cathodic rust prevention

Postby stianhat » Tue Jun 14, 2011 9:33 pm UTC

vinceat852 wrote:yes, as I said in my reply to velifer above, hong kong's weather can be the devil.
and yes, fencing jackets are usually made of a mesh of wires.
so is there anyway that I can keep them oxide-free? sacrificial protection by attaching them via a wire to a block of zinc?
and no - I can't just put oil on them; I need them to conduct electricity.

and would it be possible to simply throw on some vinegar/weak acid and just corrode off the oxide then wash out the vinegar?


Humid, hot and close to sea air. A material scientists nightmare - or wet dream if you like challenges. Even stainless steel don't do much good in those conditions.

Sacrificial protection (or cathodic protection) works only if the sacrificial anode is immersed in electrolyte. I guess you could try to connect a chunk of Zn (or maybe lead) to the jacket with a wire (try to avoid copper wire though - steel wire. And not some shiny nickel covered stuff.), then keep the chunk immersed in water or a mildly acidic water solution (1 - 5 % vinegar). Maybe, I can't confirm this from memory alone, but maybe you can use solder wire for both connector and sacrificial anode. I'll have to browse some books to check that. That would be a dirt cheap solution.

As for the oxide, use gun cleaning oil or chainsaw chain oil, that stuff works like a charm. Or brass / silver polish, but thats time consuming. You may clean the gun cleaning oil from the metal with soapy water afterwards if it is a problem.

For the long term solution I would get some electrically conducting paint or coating

Good luck.

PS: The cheapest solution is in 99% of the cases - get the correct material - which won't corrode ;)

vinceat852
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Re: Variation of Cathodic rust prevention

Postby vinceat852 » Wed Jun 15, 2011 1:51 pm UTC

Oh dear. I'd love to be able to get good jackets, but that in and of itself would bust the budget. =_=||

so my best bet is either putting them in a dessicator or connecting it to a block of zinc?

oh and yeah, one question - would it be better to wash them and leave them out to dry or to just let our sweat dry on them? (and if we should wash them, how often?)
note: (if this helps) the jacket rusts green, but doesn't look in the least bit red when new..

stianhat wrote:
vinceat852 wrote:As for the oxide, use gun cleaning oil or chainsaw chain oil, that stuff works like a charm. Or brass / silver polish, but thats time consuming. You may clean the gun cleaning oil from the metal with soapy water afterwards if it is a problem.


oh and Hong Kong doesn't people to keep guns, so what would be a household equivalent of gun-cleaner?

sikyon
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Re: Variation of Cathodic rust prevention

Postby sikyon » Wed Jun 15, 2011 6:42 pm UTC

I would have to agree that using a dessicator would be your best bet. You could also simply coat the surface in an oil (you should be able to find this at a general or hardware store), but if you are going to be using a metal mesh and have to clean the oil off every time it will become very time consuming. Coating with oil, though, should prevent rusting if the oil is reapplied regularly.

gorcee
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Re: Variation of Cathodic rust prevention

Postby gorcee » Wed Jun 15, 2011 6:58 pm UTC

vinceat852 wrote:so my best bet is either putting them in a dessicator or connecting it to a block of zinc?


Not necessarily. If the material doesn't passivate, anodic protection won't do anything for you. So all you'll have is a wet, smelly, corroded jacket wired to a block of zinc.

If humidity is your main concern, then your best bet for preventing corrosion is to reduce the humidity. Since air-conditioned storage isn't an option, then you need to think of some other solutions. I would recommend storing them in a garment bag with a box of baking soda. This will help pull some moisture out of the air, and the garment bag (ie, what you'd use to pack a suit for a trip) will prevent moist air from getting in.

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Velifer
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Re: Variation of Cathodic rust prevention

Postby Velifer » Thu Jun 16, 2011 1:07 pm UTC

Can you buy WD-40 in Hong Kong? (I think they have worldwide distribution).
http://www.wd40company.com/about/locations/

Spray on, wipe off excess. Displaces water, inhibits rust.

I always keep a can or three around in the redneck toolbox (next to the duct tape and the hammer).
Time flies like an arrow, fruit flies have nothing to lose but their chains -Marx

vinceat852
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Re: Variation of Cathodic rust prevention

Postby vinceat852 » Thu Jun 16, 2011 3:02 pm UTC

gorcee wrote:. I would recommend storing them in a garment bag with a box of baking soda. This will help pull some moisture out of the air, and the garment bag (ie, what you'd use to pack a suit for a trip) will prevent moist air from getting in.

wait. that would be the best solution, I guess. It's cheap enough. But should I rinse the jackets off from time to time to get rid of the sweat?


Velifer wrote:Can you buy WD-40 in Hong Kong? (I think they have worldwide distribution).
Spray on, wipe off excess. Displaces water, inhibits rust.
I always keep a can or three around in the redneck toolbox (next to the duct tape and the hammer).

Yes, we do - but the coating cannot be something which inhibits conduction.

gorcee
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Re: Variation of Cathodic rust prevention

Postby gorcee » Fri Jun 17, 2011 5:19 pm UTC

vinceat852 wrote:
gorcee wrote:. I would recommend storing them in a garment bag with a box of baking soda. This will help pull some moisture out of the air, and the garment bag (ie, what you'd use to pack a suit for a trip) will prevent moist air from getting in.

wait. that would be the best solution, I guess. It's cheap enough. But should I rinse the jackets off from time to time to get rid of the sweat?

The jackets should be wiped/rinsed clean of sweat for three reasons: 1.) There is such a thing as bacterial corrosion, 2.) Sweat is more electrolytic than water, 3.) It's really nasty if you don't at least wipe them clean.

Of these three reasons, #3 is the biggest argument for cleaning before storage. It even has scientific basis; diseases like Vitaligo can sit dormant and later spread through sweaty equipment.

Also, I second the WD-40 idea. That stuff is magical. To ensure it doesn't prevent conductivity (it shouldn't), spray some on a small section of the jacket, wait an hour, and test it.

Moose Hole
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Re: Variation of Cathodic rust prevention

Postby Moose Hole » Fri Jun 17, 2011 7:57 pm UTC

1) Spray with water and air dry so it gets rusty.
2) Scrub the rust off before using.
3) Go to 1.

vinceat852
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Re: Variation of Cathodic rust prevention

Postby vinceat852 » Sat Jun 18, 2011 4:22 am UTC

gorcee wrote:
vinceat852 wrote:
gorcee wrote:. I would recommend storing them in a garment bag with a box of baking soda. This will help pull some moisture out of the air, and the garment bag (ie, what you'd use to pack a suit for a trip) will prevent moist air from getting in.

wait. that would be the best solution, I guess. It's cheap enough. But should I rinse the jackets off from time to time to get rid of the sweat?

The jackets should be wiped/rinsed clean of sweat for three reasons: 1.) There is such a thing as bacterial corrosion, 2.) Sweat is more electrolytic than water, 3.) It's really nasty if you don't at least wipe them clean.

Of these three reasons, #3 is the biggest argument for cleaning before storage. It even has scientific basis; diseases like Vitaligo can sit dormant and later spread through sweaty equipment.

Also, I second the WD-40 idea. That stuff is magical. To ensure it doesn't prevent conductivity (it shouldn't), spray some on a small section of the jacket, wait an hour, and test it.


Awesome. looks like I've got a way to go about saving my equipment. *cough*
thanks!

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Re: Variation of Cathodic rust prevention

Postby gorcee » Mon Jun 20, 2011 5:10 pm UTC

Oh, and if anyone was wondering if, in a different application, whether the OP's suggestion would work, it probably would. The technique is known as impressed current cathodic protection.

vinceat852
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Re: Variation of Cathodic rust prevention

Postby vinceat852 » Tue Jun 21, 2011 6:26 am UTC

gorcee wrote:Oh, and if anyone was wondering if, in a different application, whether the OP's suggestion would work, it probably would. The technique is known as impressed current cathodic protection.

but I'd still need an electrolyte. oh well. thanks! =]


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