Chemistry

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Lab discovers titanium-gold alloy that is four times harder than most steels (phys.org)

submitted 10 months ago by [email protected] to c/[email protected]

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[–] [email protected] 3 points 10 months ago* (last edited 10 months ago) (1 children)

what the heck is passivating? That word has no cromulence for me.

[–] [email protected] 0 points 9 months ago (1 children)

Passivation (chemistry)

Passivation is the use of a light coat of a protective material, such as metal oxide, to create a shield against corrosion.

Titanium, aluminum, chromium, nickel and many other metals passivates rapidly in the presence of oxygen and water.

[–] [email protected] 2 points 9 months ago (1 children)

Thank you. I enjoyed https://en.wikipedia.org/wiki/Passivation_(chemistry). I don't see the opposite nature though as being to incongruous as the material that passivates does so such that it never really is utilized without its coating while the non passivating just never gets the coating. In both cases, in the state they are utilized, they are very unreactive.

[–] [email protected] 0 points 9 months ago* (last edited 9 months ago)

I think I get what you say : if I take your words, you could say 2 metals are "opposite in nature" in the sense that they would form a galvanic couple that would (that may) in certain conditions, inhibit the passivation.

This can happen to alloys (as well) as follows. Start with a piece of stainless steel that passivates well. Now, heat it at about 500 degrees Celsius. Doing this, you produce chromium carbide precipitates around which the alloy is depleted in chromium and though enriched in iron. The result is that, after this treatment, you would notice the metal now corrodes and rust dots appear on the surface.