What is the most corrosive resistent metal?

[ckl]

Is it stainless steel? I heard that titanium is also very good in this aspect.

Also, will SS be rusted away eventually even it is properly maintained? ( Stay away from salt water, keep cleaning etc)

Thanks for any help.

 

[freddy1]

gold

but it's a bit too soft ! (and expensive ) therefore since the Inca period, no knife maker really use it anymore !

 

[SIFU1A]

talonite is pretty corrosion resistant from what i understand,

 

[TLM]

No one answer, gold is good, some platinum group metals are better under some conditions. From the "ordinary" metals titanium, nickel and chrome are fairly good.

TLM

 

[Laceration]

H1 is pretty impressive stuff.

 

[ckl]

Thanks guys, so will stainless steel rusts eventually?

 

[Zwaplat]

YES.
Gold is the most resistant. It doesn't even form an oxide. And the only two chemicals that it reacts to are Hg and aqua regia, afaik.

 

[DGG]

Is it stainless steel? I heard that titanium is also very good in this aspect.

Also, will SS be rusted away eventually even it is properly maintained? ( Stay away from salt water, keep cleaning etc)

Thanks for any help.

Gold is the most corrosive resistent metal!

 

[trout #2]

I'll assume you are asking in reference to blade steels. I've been very impressed with H-1. There was a thread a while back where someone did extensive testing of it's corrosion resistance. I'll see if I can find it. I've got a Benchmade river knife and Spyderco Salt I in H-1 and neither has shown any signs of corrosion. I run and bike with the Salt IWB and it has been unaffected by sweat. Also, I left it in the shower for ~2 weeks with nothing besides air-drying and the blade survived unscathed. The pivot action got a little rough, but was easily fixed with a quick cleaning and lubing.

http://www.bladeforums.com/forums/showthread.php?t=344293&highlight=rust

 

[STR]

H1 steel seems pretty much the king as far as stainless goes. Titanium is very resistant to all kinds of things but you can make titanium pit out pretty easy using coke and an anodizer or 9volt batteries in series. I've caused ti to pit out from three 9volt batteries in series using diet coke to color it. (anodize it) The phosphoric acid in the coke and the voltage from the 9 volts seemed to do the trick. After I was done I swear the pits turned a rust color in the titanium. I never would have thought it possible to rust or pit out ti until then but apparently it can be done.

 

[USAFSP]

As far as blade steels go, I think that Stellite 6K and Talonite are the best, just because it can be used to cut as normal and have great edge retention. H1 is good too, but a little softer. Ti is a great alloy, but as far as edge retention it sucks.

 

[Cliff Stamp]

Talonite is softer than Beta-Ti and both are much softer than H1.

-Cliff

 

[freddy1]

as far as you are only interest about corrosion resistance, you should definitively choose a gold knife !

look at bellow knife, couple of thousand years old, and look like Ahmosis 1 just receive it from post office

egypcian gold dagger

otherwise, you should turn to non-metallic blades, that are probably even better !

like this one

silex knives

 

[kl101]

Titanium is not corrosion resistant. In fact it 'rusts' quite easily. 'Rusting' is the process of oxidizing, forming an oxide. Rust on a knife balde is Ferris Oxide ( may be actually ferrous oxide, my chemistry is a little rusty, haha). So the iron part of the steel, stainless or otherwise, forms the oxide which for iron happens to be that lovely brownish red. The alloys in stainless steels (primarly the chromium) are there to slow or retard the oxidizing process. Ferric/ferrous oxide is not a stable compound. so the oxidizing process continues.

Titanium however, forms an oxide very vigourously, but theat oxide is the same color and is extremely stable. In fact titanium oxides so vigorously that in some conditions it will actually burn. So titanium oxides are the corrosion resistant part, not titanium itself.

 

[Joe Talmadge]

Thanks guys, so will stainless steel rusts eventually?

Yes, stainless steels can rust eventually. Depending on the particular stainless steel and the finish, it might be really rust resistant, or just marginally rust resistant. That is, there's a continuum of how rust resistant it will be, but all stainless cutlery steels can rust eventually. That's cutlery steels -- I don't know whether a non-steel products such as talonite will, as a practical matter, show rust.

 

[Walking Man]

Titanium however, forms an oxide very vigourously, but theat oxide is the same color and is extremely stable.

HOLD ON, there Tex......
I don't know if it's true or, let's get some experts on this subject, a while ago, it was said that Titanium does rust, but it rusts very slowly, and it rusts white. It was also commented that this rust is used as pigment for white paint. Can anyone confirm either way?

 

[HoB]

You are both right. TiO2 is white and used as a pigment and as a polishing agent, but it is also the reason why Ti doesn't corrode. It is not so much how easily a material corrodes but whether the oxide layer is "air tight" or porous. ferrous oxide is porous so the oxidation continous...even worse the ferrous oxide acts as a catalyst accelerating oxidation under the right conditions. Both Aluminum and Ti form a "tight" oxide layer. With Al you often have to help the oxidization along to get it uniform enough. That is called anodizing.

A bit of trivia here. There is something called an electrochemical potential. This is the positive voltage that is necessary to extract electrons from the material. It is an academic measure how readily a material oxidizes. It is very acurately measureable but it has little bearing on real world conditions. With a sufficiently large potential even gold can be oxidized (Gold plating is the reverse process, btw.). However, there are metals, where you do not even have to apply a positive potential, because they release their electrons very readily. In such a case you measure the negative potential that is necessary to stop the release of electrons. Aluminum is a fast and violent reaction. Very fine Al power is even self ignitable. But on the grand scale of things even Al is considered only moderately reactive, when compared to metals like Potassium and Sodium. You know, the things that go BOOM, when you throw them in water. An alternative form to adjust the potential of the surrounding, essentially equivalent to applying a potential, is to decrease the pH value of the medium the metal is placed in. Sulfuric Acid will corrode most metals. Only very few metal are resistant to Sulfuric Acid. Gold is among those. Even Aqua Regia relies on a little trick, it is not strict oxidation. Aqua Regia is nitric acid mixed with HCl. The nitric acid is a strong oxidizer and is able to oxidize very, very lightly the Gold, but the equilibrium of the reaction is far on the side of the Gold. The chlorine removes the gold atoms extracted by the nitric acid by forming a AuCl complex. So you constantly "deplete" the equilibrium in disfavor of the Gold.

Ok, I know, WAYYYY too much information. Sorry .

 

[robertmegar]

X-15 is also very corrosion resistant, maybe on par with H1 but with better edge holding

 

[GarageBoy]

Hows platnum?

 

[Murky Depth]

You are both right. TiO2 is white and used as a pigment and as a polishing agent, but it is also the reason why Ti doesn't corrode. It is not so much how easily a material corrodes but whether the oxide layer is "air tight" or porous. ferrous oxide is porous so the oxidation continous...even worse the ferrous oxide acts as a catalyst accelerating oxidation under the right conditions. Both Aluminum and Ti form a "tight" oxide layer. With Al you often have to help the oxidization along to get it uniform enough. That is called anodizing.

A bit of trivia here. There is something called an electrochemical potential. This is the positive voltage that is necessary to extract electrons from the material. It is an academic measure how readily a material oxidizes. It is very acurately measureable but it has little bearing on real world conditions. With a sufficiently large potential even gold can be oxidized (Gold plating is the reverse process, btw.). However, there are metals, where you do not even have to apply a positive potential, because they release their electrons very readily. In such a case you measure the negative potential that is necessary to stop the release of electrons. Aluminum is a fast and violent reaction. Very fine Al power is even self ignitable. But on the grand scale of things even Al is considered only moderately reactive, when compared to metals like Potassium and Sodium. You know, the things that go BOOM, when you throw them in water. An alternative form to adjust the potential of the surrounding, essentially equivalent to applying a potential, is to decrease the pH value of the medium the metal is placed in. Sulfuric Acid will corrode most metals. Only very few metal are resistant to Sulfuric Acid. Gold is among those. Even Aqua Regia relies on a little trick, it is not strict oxidation. Aqua Regia is nitric acid mixed with HCl. The nitric acid is a strong oxidizer and is able to oxidize very, very lightly the Gold, but the equilibrium of the reaction is far on the side of the Gold. The chlorine removes the gold atoms extracted by the nitric acid by forming a AuCl complex. So you constantly "deplete" the equilibrium in disfavor of the Gold.

Ok, I know, WAYYYY too much information. Sorry .

*gets chilling flashback of chemistry class.. then remembers cute lab partner*