WHILE LOOKING AT SOME OF THE THREADS HERE ?

[nomad 11]

I thought of this ? anybody know how long copper would have to be in the ground to become brittle ? over time i found an old shell casing. i think it was a .45 when i tried cleaning out the dirt it started breaking apart so i just left it be. then another time i found an old belt buckle with each initial engraved on it. they were separate pieces. 3 initials when i started to clean them one broke right in half. and that peeved me. then i lost interest. and i dont know what i even did with them. i was guessing they had to be from the mid 1800's. because i never thought copper would become brittle at any point. so just wonderin ? anyone else ever experience this ?

 

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[Charlie P. (NY)]

Shell casings are not copper. They are brass. Brass is an alloy of copper and zinc. Zinc is VERY reactive to ions and acids and dissolves over time - leaving a crumbly matrix in the shell.

It even has a name: dezincification.

https://www.nace.org/Corrosion-Central/Corrosion-101/Dezincification/

It can be a REAL problem where brass and bronze valves are used. People have died unpleasantly when brass or bronze steam fittings failed.

 

[against the wind]

A more obvious form of disintegration is evident in what we call a Zincoln.
I have dug hundreds of brass rifle shells over the years in various stages of zincification.

 

[Dave Rishar]

I thought of this ? anybody know how long copper would have to be in the ground to become brittle ?

Are you sure that it's copper, and not brass or iron or something else? Copper does not normally get brittle out in the wild unless you're bending it back and forth.

Shell casings are not copper. They are brass. Brass is an alloy of copper and zinc. Zinc is VERY reactive to ions and acids and dissolves over time - leaving a crumbly matrix in the shell.

It even has a name: dezincification.

https://www.nace.org/Corrosion-Central/Corrosion-101/Dezincification/

It can be a REAL problem where brass and bronze valves are used. People have died unpleasantly when brass or bronze steam fittings failed.

This. That might be what happened to your belt buckle, nomad 11. A telltale is that your brass artifact is red after cleaning. That red color is caused by the zinc being leached out of the brass, leaving you with a spongy (and possibly crumbly) copper leftover. I actually deal with this a lot in my part of the world, due to the amount of rain that we get and the acidic nature of the soil. If the cartridge case's crumbling is worst at the mouth (where the brass is thinnest) and isn't really an issue at the base (where it's very thick) - and it's red - you're almost certainly dealing with acid leaching the zinc out of your brass.

This next bit doesn't apply to your belt buckle, but it may apply to your cartridge casing: mercuric priming. Mercury fulminate was a very effective priming compound for black powder, and the nature of black powder ignition tended to conceal its drawbacks. Once the world transitioned over to smokeless, mercuric priming compounds went away more or less quickly, as its problems became impossible to ignore. One of those was the deposition of mercury inside the cartridge casing with high heat and pressure, which (due to SCIENCE) sometimes made the casing brittle. If you're dealing with an old, crumbly cartridge case, it may be due to a mercuric primer.

Or it may not. Was it red when you dug it up?

 

[nomad 11]

yep i saw red. thats why i believe it was copper. and if i ever find them (where i put them) i'll post pictures someday. to prove my point. so stay tuned. and if i forget just remind me. K damn those anti depressants !

 

[nomad 11]

Shell casings are not copper. They are brass. Brass is an alloy of copper and zinc. Zinc is VERY reactive to ions and acids and dissolves over time - leaving a crumbly matrix in the shell.

It even has a name: dezincification.

https://www.nace.org/Corrosion-Central/Corrosion-101/Dezincification/

It can be a REAL problem where brass and bronze valves are used. People have died unpleasantly when brass or bronze steam fittings failed.

as to the saying at the bottom of your post there Charlie ? where are those hell raisers today ? inquiring minds want to know ? i'm still waitin. i am. i am.

 

[ToddsPoint]

I worked in a machine shop, part of a valve factory. We made valves for ships out of what we called "naval brass", which had either less zinc or no zinc. Naval brass bar stock was always dirty/splotchy looking, unlike the yellow or red brass bars. Gary