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cako82 t1_j5rraih wrote

Reply to comment by Shotgun81 in Reducing the carbon footprint of the steel industry could help curb climate change, but these improvements won't happen without international policy change, new research says. by Impossible_Cookie596

How effective is the use of phosphoric acid on the surface of steel? i have used it in the past to treat surface level corrosion, prior to apply a layer of protection. interested in your opinion.

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Shotgun81 t1_j5s1zt4 wrote

It's great for what it does and is a useful cleaning agent to prepare many types of stainless steel for a protective coating. However, you do have to be aware of the type of stainless steel you have before you use it. Off the rope of my head, I seem to recall that there are a few varieties of stainless that have additives that can react badly with the phosphorus... plus just plain impurities like chloride can potentially set up micro areas of intense corrosion.

I believe there are charts available with a Google search that can outline the compatability of different stainless steels with phosphoric acid.

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cako82 t1_j5s3b6n wrote

Never used it on stainless steel tho, for stainless I have used zinc anode on marine weathers, the phosphorus acid on carbon steel, was a tip that a chemical engineer gave while ago for treat corrosion prior to apply a protective layer. Appreciate the answer for expanding the uses of the component.

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Shotgun81 t1_j5s64o0 wrote

Hmmm... I've never used it on carbon steel. Cool, I'll have to check it out. If it does apply a protective layer, I would think it does so by pre-corroding the top layers, similar to the galvanic coating on galvanized steel pipes and fittings.

I'd have to look more into it to know how durable the coating is, once it is scratched or worn, it would of course be useless.

Edit: you also have to check the permeability of the corrosion product coating. If it's too permeable it's also significantly less useful.

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