How can I tell what kind of bronze?

Date 10-22-2003 16:17

If you really need to know, send it to a lab, capable of positive material identification testing (PMI) and have them sample it. Our experience is that the cost is about $100. They will provide you with a complete chemical ananlysis and they should be able to list all the UNS numbers that the material chemistry conforms to. From the UNS you will be able to track down the material specification and grade.

We typically use a company called New Hampshire Materials, but there are many others.

Charles Hall

By 49DegreesNorth (**)

Date 10-22-2003 19:25

Thanks -- the key here is to not spend money on this, though. I got this stuff in a scrapyard, and I only got like 20 pounds of it. I was hoping someone might have a cheapo, seat-of-the-pants kind of assay.

Thanks anyway, Charles!

Chris

By rodofgod (**)

Date 10-22-2003 22:03

Hi 49DegreesNorth,

Read your other postings concerning your welding problems!
Check http://www.welding-advisers.com/index.html
I think the problem is that there is that many alloys of Copper, Bronze, Brass, Zinc etc, all with different welding and mechanical properties. I don't know of any 'Workshop' test to differentiate between all the alloys out there!
I would be careful trying to weld the stuff, most of the Copper/Zinc alloys can give off some nasty fumes!!!! Watch out for that 'black' slag! That would start to ring alarm bells to me!
Sorry I can't be more helpful.

Glenn Webb

By billvanderhoof (****)

Date 10-23-2003 03:40

There are two properties that I can think of that may help. Density- determine the volume of a sample (measuring the water it displaces is a good way) then weigh it. Divide weight in grams by volume in cubic centimeters. Almost all alloying agents for copper will produce an alloy with lower density. Melting point- it may be hard to measure these temperatures (ceramic cones are a possibility as are temp sticks) you could however compare with known alloys like brazing rods. Electrical wire is as pure copper as you will find. Generally alloys will have lower melting points.

Your old chemistry teacher may be helpful.

Good luck
Bill

By G.S.Crisi (****)

Date 10-22-2003 22:29

If your point is not to spend money, here are some clues:
1. Pure copper is of reddish brown color, more or less like the "penny" (one cent) coins in the USA.
2. Bronze is yellowish brown, clearer than pure copper.
3. Brass is yellow.
Put a drop of liquid ammonia (ammonia solution, actually) on the material. If it gets blue it means that the material definetely contains copper. From the color you'll be possibly able to identify it.
It should be said, however, that only a chemical analysis is 100% reliable.
Giovanni S. Crisi
Sao Paulo - Brazil

By 49DegreesNorth (**)

Date 10-24-2003 19:42

Thanks for all the helpful replies! The density test is one which I had considered, although I don't think I could get accurate enough to tell high-copper alloys from pure copper. Melting point, though, hmmmm...

Actually I think that what I have is, in fact pure copper given the properties it exhibited while welding: vy. high conductivity, black stuff forming on it, slightly more coppery color than my silicon bronze rod.

Chris

By brande

Date 10-30-2003 06:36

Regardless of what it may or may not be, aluminum bronze A-2 should be able to join. Unless, of course, certain conductivity or related properties must be maintained.

Copper is a pain-it must be run hot, but surface temps in excess of 900 degrees F or so let the copper absorb contaminates from the atmosphere (carbon monoxide the prime culprit).

If welding with mig or tig, a helium addition would definitely mak the day easier.

I've done a bit of this. Any particular questions, email direct.

Many Thanks

Good Luck

brande