What would happen if you put a bit of sacrificial metal on a knife to stop rust.

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Drop bear

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Which is a process I don't really understand. But I think they do it with cars or something where they put a slab of magnesium or something to stop steel rusting.
 
Sacrificial anodes usually wear away (sacrificial), and end up looking sort of eroded and crappy. (crappy is a technical term.... :rolleyes: )
I don't think that would be good on a knife. Especially when it's relatively easy to prevent bad rust from happening anyway.
 
sacrificial anodes would probably make your knife pretty ugly. The gist of them is that they are more reactive than the material around them and thus sacrifice themselves instead of allowing corrosion to eat what you don't want to be eaten by corrosion. They are generally in an area where they are out of sight slowly being worn away as they do tend to look chalky and...well, corroded. Usually you find them in areas where there is a high degree of electrolysis among materials that would be overwhelmed by this. I would think that with today's super stainless steels, they are able to fight off pocket sweat better (and look better doing it) than going with something like a carbon steel blade and some sort of sacrificial anode.
 
Steely_Gunz said:
sacrificial anodes would probably make your knife pretty ugly. The gist of them is that they are more reactive than the material around them and thus sacrifice themselves instead of allowing corrosion to eat what you don't want to be eaten by corrosion. They are generally in an area where they are out of sight slowly being worn away as they do tend to look chalky and...well, corroded. Usually you find them in areas where there is a high degree of electrolysis among materials that would be overwhelmed by this. I would think that with today's super stainless steels, they are able to fight off pocket sweat better (and look better doing it) than going with something like a carbon steel blade and some sort of sacrificial anode.
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It would have to be cheaper than a super steel though.
 
Drop bear said:
It would have to be cheaper than a super steel though.
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Well yes and no. I mean the components by themselves could be cheaper, I guess. However, the engineering to where it would be practical in anything but the most academic of ways would carry with it either a monetary cost or at the very least being ok with some frankensteined knife. Sacrificial anodes aren't perfect either. They tend to limit corrosion but usually don't stop it all. Even that has to do with with the technology you are using. You can keep salt water used to produce chlorine from reacting to the surrounding steel via a specialized flow-through that will severely limit the ability to react with what you don't want it to react with...or you can toss a chunk of zinc in the water and let it chew on that passively instead of the other material. It will work. It will be cheaper. I just won't do as good of a job.

Also the way a SA corrodes is messy. So while you won't technically rust your knife, you'll be left with some pretty gnarly looking stuff on it.

Now, this can use a similar process to REMOVE rust as well. Instead of using a piece of zinc, you can use baking soda, an old iron rod, and a weak electrical current to pull rust off of steel and deposit it on the iron bar. I learned about this on a black powder forum regarding removing rust from barrels. I've tried it with decent results.
 
I don't think it would work the way you wanted it to, either, as in preventing rust on the parts of the knife you care about.

What we're talking about here is "Galvanic corrosion". For it to work though, there has to be a complete electrical circuit, among other things. It works with ships, because they spend all their time in a medium which is just peachy for conducting electricity. Your skin is dielectric under most conditions, which means you are a pretty lousy electrical circuit. The corrosion process on knives is chemical oxidation, not electro-chemical oxidation.

tl;dr, you would get a nasty piece of rust hanging off your knife, and nasty rust on the rest of your knife too, if you didn't take care of it.

More to the point: what are you doing that you even need this kind of rust protection? H1 exists, and there are at least three ways to coat a non-stainless blade for equal, if not better, oxidation protection.
 
Shorttime said:
I don't think it would work the way you wanted it to, either, as in preventing rust on the parts of the knife you care about.

What we're talking about here is "Galvanic corrosion". For it to work though, there has to be a complete electrical circuit, among other things. It works with ships, because they spend all their time in a medium which is just peachy for conducting electricity. Your skin is dielectric under most conditions, which means you are a pretty lousy electrical circuit. The corrosion process on knives is chemical oxidation, not electro-chemical oxidation.

tl;dr, you would get a nasty piece of rust hanging off your knife, and nasty rust on the rest of your knife too, if you didn't take care of it.

More to the point: what are you doing that you even need this kind of rust protection? H1 exists, and there are at least three ways to coat a non-stainless blade for equal, if not better, oxidation protection.
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I live on a tropical rainforest by the coast.

Cotton rusts here.
 
It wouldn't work the best for this application. Coatings are a better solution.

The plated metal used for corrosion reistance has a shelf-life and it would be harder to strip and recoat than with a coating.

Something I've never seen before, until recently, is an actual knife with an electroplated metal as a surface finish. Maxpedition did it for a little while with a plated hard chrome finish. I picked up 2 on the exchange recently but I've yet to see how it performs. Hard chrome is an ugly finish compared to polishing the blade or using a decorative coating like you see on the showy pieces on cars.

I worry more about hydrogen embrittlement since high carbon steels are more prone to it from the plating process, though that's not the type of plating I have direct experience with, just text book education for those processes.
 
Not for nothing, but a little preventative maintenance goes a long way. I worked every day for many years in a salt rich environment. Salt rich as in sometimes up to my ankles in sodium chloride, the air full of salt dust, working on equipment full of mag chloride, calcium chloride and sodium chloride brine solution. I used my knives regularly to cut damaged hoses for replacement and they were always covered with some sort of corrosive salt. Everything got washed thoroughly and oiled when needed. Never had a problem with rust.
For instance, I carried this Spyderco C-44 Dyad and Leatherman for 20 + years at work with no real problems.
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there is this amazing new tech -- they developed something called stainless steel -- which has chrome & does a much better job than any sacrificial anode could...

you can still force rust on it, but usually need to leave it in saltwater for a long duration ;)
 
Maybe give Sandrin knives a look? They make their blades out of tungsten carbide. Larrin brought up the possibility that the cobalt binding material might corrode. You could maybe get Sandrin to let you test one for them.

There are companies making knife blades out of ceramic. Some of them for $30 on the big river website. Your mileage may vary.
 
I've got a few Maxpedition knives that are chrome plated over D2.

I have no idea if it does anything other than look cool.
 
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