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Post by nightsky02 on Jan 21, 2009 0:48:47 GMT -5
OK, this may sound stupid to many of you guys, but I have a difficult time differentiating brass from bronze.
My father has aquired a few hundred pounds of brass and bronze, but I cant tell them apart. I mistakenly made connecting rod and driving rod bushings from brass, and now they are worn out. Apparently, brass and bronze arent interchangeable, even though they are both yellow (lol).
I am aware that bronze is generally a darker color, but I`ve used aluminum bronze that has same color as brass.
I tried testing hardness by filing and center punching, but this doesnt appear to be a relaible method.
Also, can anyone tell me if oil impregnated bronze (oilite) is better than phosphorous bronze for a radial bearing?
Ed Hume, this question is directed at you, after seeing your fine work, but I`d love to hear from anyone who has any insight on this.
Thanx,
Ron Hermans
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Post by Ed Hume on Jan 21, 2009 8:59:38 GMT -5
Hi Ron,
My experiences with brass and bronze are limited - mostly brass 360, and the 932 bearing bronze and phosphor bronze 510. These materials are very different looking. The 510 bronze looks like copper.
One big clue is the outer dimensions and color - brass seems to be always be an even stock dimension and the outer color is uniform. The bearing bronzes seem to be mottled in color on the outside, not perfectly round, and a little oversized.
I have heard of the following method but never tried it - take some filings and burn them under a torch. If you get white residue, that is zinc oxide so the material was brass.
Ok guys any other suggestions?
Ed
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Post by Dan Rowe on Jan 21, 2009 10:04:00 GMT -5
As Ed said the color is the best indicator. Bronze has a higher percent of copper than brass. Having said this red brass (US name) is the same as gunmetal (UK name) so the comon names are misleading.
I will have to try the torch method for looking for zinc which is only in brass.
Dan
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Post by Dan Rowe on Jan 21, 2009 19:12:24 GMT -5
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Post by Ed Hume on Jan 21, 2009 20:02:50 GMT -5
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Post by Dan Rowe on Jan 22, 2009 8:09:38 GMT -5
Hi Ed,
Thanks for that link. Chemical analysis is the way to go but most home shops are not that sophisticated.
The article will not be useful for finding either silicone or aluminum bronze which do not contain tin.
Dan
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Post by Ed Hume on Jan 22, 2009 8:31:02 GMT -5
I don't think its as impractical as you might think. In the old days you could buy chemicals like nitric acid at the pharmacy - maybe you still can. But if you have a connection to a high school or college chemistry teacher, you could print out the article and visit with some samples.
If you have any friends that work in a lab setting - and that includes hospitals, police crime labs, and high tech companies - ask them if they have an energy dispersive X-ray system (eg Kevex is a manufacturer). They can determine elemental compositions easily. When I worked at IBM Boulder in the late 70's we had one just to analyze problems with parts.
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Post by Dan Rowe on Jan 22, 2009 8:50:38 GMT -5
Hi Ed,
Yes there are lots of locations to get the analysis done, I simply said that most home shops are not equiped for the task.
I know there are firms that will do this but that adds to the expense of surplus metal.
Dan
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Post by nightsky02 on Jan 23, 2009 2:21:34 GMT -5
Thanx everyone for your suggestions!
I guess Dan had the best idea, just buy new metal. Shouldve been obvious, huh?
Also, I found last night that I can tell some differences between brass and bronze when I`m drilling in lathe. The shape of the chips, the feed resistance, and the sound.
Generally, I try to avoid police crime labs, hospitals, and and x ray machines shooting gamma rays at me. Was only trying to save 10 bucks.
Ty,
Ron
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bruce
Gandy Dancer
Posts: 15
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Post by bruce on Feb 22, 2009 14:47:36 GMT -5
Agaiin thanks for this thread! Here in LA, CA there are lots of surplus houses and you can find grungy brass and bronze at ridiculous prices. I've bought some of this stuff and wondered what it really is. I've been wondering if there might be an "acid test" and through this link found out that yes, there is.
Bruce
Bruce
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Post by jbodenmann on Jun 16, 2009 22:04:04 GMT -5
One thing that can be helpful is to label material with a paint pen or magic marker. That makes identification later much easier.
Jack
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Post by yorkshireman on Jun 26, 2009 6:18:18 GMT -5
There is a simple way. Chemists know it... Put some flakes of the metal in question plus some flakes of Zinc or Aluminium into a glas bowl. Pour some diluted Hydrochloric Acid (HCl) over this. Let it react for some time. Then stick a thin test-tube full of cold water into the mixture and hold the bottom end of the test-tube with some drops of the reaction mixture on its outside into a colourless gas-flame. If there was Tin present in the suspect alloy, then the flame around the test-tube will illuminate in a characteristic light-blue colour. This is perfect proof that there was Tin (i.e. bronce = Copper-Tin alloy) present. Explanation: Bronce is dissolved by the acid, forming Cu and Sn ions. Some of the Sn ions are reduced by the Hydrogen into a Tin-Hydrogen compound, SnH4. SnH4 is dissolved in the muxture. When SnH4 decomposes in the flame around the test-tube, it changes the colour of the flame into this light blue. Chemists call this the simple Test for Tin. Sounds complex, but actually is quite simple. upload.wikimedia.org/wikipedia/commons/thumb/0/00/Leuchtprobe1.jpg/491px-Leuchtprobe1.jpgupload.wikimedia.org/wikipedia/commons/thumb/f/fa/Leuchtprobe2.jpg/550px-Leuchtprobe2.jpgJohannes |
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