What are cost effecient ways of doing chemical analysis of ferrous alloys in steel?
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Usman K asked:
I would like to get information for the products (other than Spectrometer, and physical laboratory testing through reactions). available in market that allow to do a chemical analysis of mild steel. i would be interested in finding the following elements manganese, silicon, nickel, chromium, aluminium, molybdenum and copper. Also not forgetting the ‘impurities’ such as phosphorous and sulphur.
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I would like to get information for the products (other than Spectrometer, and physical laboratory testing through reactions). available in market that allow to do a chemical analysis of mild steel. i would be interested in finding the following elements manganese, silicon, nickel, chromium, aluminium, molybdenum and copper. Also not forgetting the ‘impurities’ such as phosphorous and sulphur.
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September 19th, 2008 at 8:01 am
You might find an answer to your question in an article by Bradner Wheeler.
September 22nd, 2008 at 1:30 pm
These elements ought to be heavy enough for handheld X-ray spetrometry. After an initial cost of some 15.000 Euros and upwards the cost for analyzing a sample is just operator time.
Any wet chemical approach will be more cost intensive for routine analytics.
If you need low cost analysis with school laboratory equipment, wet chemistry will do.
You will need a glass flask, smoking hydrochloric acid, a heater for temperatures up to 150°C, a cooler attachable to the glass flask, and a gas washing device attachable to the cooler filled with hydrogen peroxide solution.
Use of aqua regia or even just addition of hydrogen peroxide may inactivate some steel alloys.
Phosphorous and sulphur will be transported as hydrids and retained in the gas washing device. Phosphate can be measured gravimetrically by adding calcium and repeated rinsing of the solid with distilled water. Sulphate can be measured gravimetically as Barium sulphate, either from the remaining liquids or as mixture of Barium sulphate and phosphate with known phosphate content.
The solution in the flask will contain lots of iron and traces of the target elements Mn, Si, Ni, Cr, Al, Mb and Cu.
Si will form a gel-like solid or colloid under these conditions. The gel might be filtered off if you’re lucky. Gravimetric detection will have a huge error.
Cu may be felled as sulphide at pH 1-2 and gravimetically determined.
Mn, Mb and Cr can be separated from the dissolved iron in neutral to mildly alkaline solution after being oxidized to permanganate and chromate. Fe(OH)3 will retain some traces and may need to be dissolved and re-felled again.
Al can be separated in alkaline solution. Avoid use of glass containers, since Al will be leached from the glass as well.
Ni (and Co) will be hardest to separate by wet chemistry. Ni might be separated from the Fe(OH)3 with fairly concentrated Ammonia solution and subsequent felling as sulphide at pH 8.