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Distinguishing Test for Phosphor Bronze

Is there a Chemist in the House ? ...

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Michael Gilligan06/12/2018 10:07:43
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I need to make a small leaf spring, and Phosphor Bronze would seem the most appropriate material.

The original component was 0.020" thick, but 0.5mm should be near enough angel

Material is available, but not inexpensive; so I thought I might see if I had anything in my stock of offcuts and salvage.

This brings the problem of identification.

An internet search disclosed one helpful 'Distinguishing Test' published in 1930

**LINK**

https://books.google.co.uk/books?id=OigDAAAAMBAJ&pg=PA92&lpg=PA92

I am guessing that this detects the Phosphorous content; so the questions are:

  1. by what reaction ?
  2. is there an easier/cheaper alternative test ?

Thanks

MichaelG.

Edited By Michael Gilligan on 06/12/2018 10:08:08

Phil Boyland06/12/2018 12:56:52
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If you can file some off and post it I can check the chemical composition on our electron microscope in work for you.

All for free

Michael Gilligan06/12/2018 13:12:08
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Posted by Phil Boyland on 06/12/2018 12:56:52:

If you can file some off and post it I can check the chemical composition on our electron microscope in work for you.

All for free

.

Phil,

That's an amazing offer ... Many thanks

I will send you a personal message later today.

MichaelG.

Fowlers Fury06/12/2018 13:13:21
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I've relied on a quick test before now, no guarantee of its infalibility.
Thoroughly degrease and immerse the metal in dilute mineral acid (I use HCl). Those bronzes containing Zn usually acquire a "copper colour" as the surface Zn is dissolved away. PB, containing no Zn, remains uncoloured.

SillyOldDuffer06/12/2018 13:28:56
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I've got an old Chemistry Book on Qualitative Inorganic Analysis that's good on test tube methods: guess what - it's nowhere to be found!

From first principles though, a solution of Ferric Chloride with Hydrochloric Acid would dissolve copper. (Ferric Chloride is used to etch printed circuit boards.)

I guess the solution removes a layer of Copper from the test alloy and in the process creates a complex mix of ions. Then the Iron ions react with any exposed Phosphorous to form something like Iron Phosphate. Iron Phosphate is the blue-black layer left by some rust treatments.

Phil's electron microscope is the bees knees! Test tube analysis was on the way out back when I was at school with Noah. Although many basic chemical tests are easy, others required a lot of skill. I'm always amazed at what people achieved in the past with simple equipment and clever technique. We truly stand on the shoulders of giants.

Dave

Michael Gilligan06/12/2018 13:36:46
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12025 forum posts
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Thanks to FF and S.O.D.

Although Phil's offer obviously trumps everything, it would be good to continue this discussion so that we have a DIY answer available for next time.

MichaelG.

Michael Gilligan06/12/2018 13:45:28
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Posted by SillyOldDuffer on 06/12/2018 13:28:56:

... Then the Iron ions react with any exposed Phosphorous to form something like Iron Phosphate. Iron Phosphate is the blue-black layer left by some rust treatments.

.

Yes, that was my thinking ... like Jenolite treatment, but with all the right chemicals in all the wrong places !

MichaelG.

Phil Boyland06/12/2018 14:29:27
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Ok cool, will look out for a message.

Composition can be measured by measuring the x-rays coming off the sample whilst it's bombarded with electrons. This is a useful by product of the electron stream being used to create an image. Will send you a few screenshots too if you like as it always looks fascinating.......well to me at least. Science nerd!!

Pete Rimmer06/12/2018 19:27:05
178 forum posts

is that similar to how the zapper guns work that the scrap yard use?

Phil Boyland07/12/2018 07:48:53
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I think they work on X Ray fluorescence principle(XRF) where as I am working on the Energy Dispersive X ray principle(EDX). I don't user the former, but you can only look at a whole sample with XRF so if you have several different materials present, it would not tell you the alloy just a % of the elements present that you would not be able to classify. This is more suited to samples you know already are only one material.

With EDX you can pin point a particular particle in a sample and get its composition. Excellent for jumbled up metallic debris in a engine filter for example..

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