WTH copper brass?


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snuffy
March 29, 2011, 06:35 PM
I can find more ways to screw up! What's happened to this load of brass in my HF sonic cleaner?

http://photos.imageevent.com/jptowns/cannont2ifolder/websize/IMG_0318.JPG

http://photos.imageevent.com/jptowns/cannont2ifolder/websize/IMG_0319.JPG

I was running some mildly corroded LC brass,(new,never fired), through to remove the water caused corrosion. I had already done 3 batches with no problems. Using the new Hornady one shot case clean solution.

What was different for this load was I had dropped a steel shoe horn into it to see if it would remove the rust. I forgot it was in there, dropped the 100 cases in and started it up.

Maybe somebody on here with chemical knowledge will tell me why the brass that was in close proximity to the steel shoe horn was discolored to a copper color. The steel was covered in a black powder, as were some of the copper colored brass. They have been through a 2 hour tumble in my vibratory cleaner with corn cob and nu finish/flitz polish.

I'm aware of the fact that brass that turns copper color is probably missing zinc, or the zinc has leeched out of the brass. Almost looks like electrolysis has taken place. But where did the electrical charge come from?

I won't try to load ANY of the brass involved because it may be weak, at least not until I find out what happened. Waddaya think?:confused:

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blarby
March 29, 2011, 07:08 PM
Not sure of the exact combination of metals in your shoehorn...but by adding citric acid and zinc you've basically made a large one cell battery in your ultrasonic tub.

Don't mix metal types and acid solutions.

snuffy
March 29, 2011, 08:44 PM
Maybe I should have galvanic reaction, like in galvanizing zinc onto steel?

If for no other reason, this is to warn everybody using acidic acid to clean brass in a U.S. cleaner NOT to include any other metal in with the brass.

I dumped the solution, and I may junk the brass just to be on the safe side.

Apparently the stainless tub of the cleaner has no concerns with what's in it.

snuffy
March 30, 2011, 01:00 AM
I put this on several other boards, it turns out to be a galvanic reaction. Actually it could be reproduced any time. 2 different metals in an acid bath and heat made it happen pretty fast. Zinc and steel are pretty close on the galvanic chart, but copper is way up. The heat caused it to happen faster.

Into the brass recycle bag they all go! Chalk it up to my lousy memory and ignorance.

243winxb
March 30, 2011, 09:13 AM
I wonder why there is a difference between the stainless tub of the cleaner & the steel shoe horn? :confused: Interesting.

ambidextrous1
March 30, 2011, 09:24 AM
Stainless stel isn't very active, galvanically. The nickel and chromium in the stainless alloy account for this.

Stainless steel can also be [I]passivated[I], to further modify its galvanic potential.

243winxb
March 30, 2011, 09:39 AM
Know we know, thank you, ambidextrous1

snuffy
March 30, 2011, 12:59 PM
Here's a galvanic chart I found on Google. From a company called;
GRABBERGARD

G001. GALVANIC CHART
CORRODED END (ANODIC OR LEAST NOBLE)
MAGNESIUM
MAGNESIUM ALLOYS
ZINC
ALUMINUM 5052, 3004, 3003, 1100, 6053
CADMIUM
ALUMINUM 2117, 2017, 2024
MILD STEEL (1018), WROUGHT IRON
CAST IRON, LOW ALLOY HIGH STRENGTH STEEL
CHROME IRON (ACTIVE)
STAINLESS STEEL, 430 SERIES (ACTIVE)
302, 303, 304, 321, 347, 410,416, STAINLESS STEEL (ACTIVE)
NI - RESIST
316, 317, STAINLESS STEEL (ACTIVE)
CARPENTER 20 CB-3 STAINLESS (ACTIVE)
ALUMINUM BRONZE (CA 687)
HASTELLOY C (ACTIVE) INCONEL 625 (ACTIVE) TITANIUM (ACTIVE)
LEAD - TIN SOLDERS
LEAD
TIN
INCONEL 600 (ACTIVE)
NICKEL (ACTIVE)
60 NI-15 CR (ACTIVE)
80 NI-20 CR (ACTIVE)
HASTELLOY B (ACTIVE)
BRASSES
COPPER (CA102)
MANGANESE BRONZE (CA 675), TIN BRONZE (CA903, 905)
SILICON BRONZE
NICKEL SILVER
COPPER - NICKEL ALLOY 90-10
COPPER - NICKEL ALLOY 80-20
430 STAINLESS STEEL
NICKEL, ALUMINUM, BRONZE (CA 630, 632)
MONEL 400, K500
SILVER SOLDER
NICKEL (PASSIVE)
60 NI- 15 CR (PASSIVE)
INCONEL 600 (PASSIVE)
80 NI- 20 CR (PASSIVE)
CHROME IRON (PASSIVE)
302, 303, 304, 321, 347, STAINLESS STEEL (PASSIVE)
316, 317, STAINLESS STEEL (PASSIVE)
CARPENTER 20 CB-3 STAINLESS (PASSIVE), INCOLOY 825
NICKEL - MOLYBDEUM - CHROMIUM - IRON ALLOY (PASSIVE)
SILVER
TITANIUM (PASS.) HASTELLOY C & C276 (PASSIVE), INCONEL 625

As can be seen, zinc and steel are pretty close together. But nickle is further down, so if the shoe horn was plated with nickel, it reacted more. Then add heat to the equation, faster reaction.

http://photos.imageevent.com/jptowns/cannont2ifolder/websize/IMG_0327.JPG

The shoe horn has a logo from "miller jones footwear Co" on it. Dad used to order shoes from them, they sent a shoe horn with each pair of shoes.

918v
March 30, 2011, 01:50 PM
I think your brass looks nice. I like the colors. Reminds me of pre-war S&W color case hardening.

Ruger GP100 fan
March 30, 2011, 05:00 PM
...but by adding citric acid and zinc you've basically made a large one cell battery in your ultrasonic tub.

..and may have just stumbled upon a perpetual motion machine by powering the tumbler with the current:rolleyes:

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