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Letter 3451
Alternative to Ferroxyl testing & Spot
Indicator of Chromium and/or Nickel
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I am trying to find a porosity indicator for Electroless Nickel
type coatings on steel that *does not* contain potassium ferrocyanide
(Ferroxyl Test). Is there any other indicator that indicates presence
of iron?
I have also seen references to submerging in boiling water. Has
anyone had experiences pro or con these two methods?
Also, is there anything to detect presence of hard chromium or
nickel on a steel surface as a *color indicator* spot test
(recognition by the appearance alone is difficult on some exotic
materials) I would prefer to not use droplets of HCl and looking for
gassing or discoloration.
H. Sencza
- Canada
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The copper sulfate spot test may be a useful alternative to the
ferroxyl test. This test plates out copper on to expose iron
surfaces. The holiday size resolution for a copper spot, however, may
not be as good as for the bright blue indication in the ferroxyl
test. The method is used often for checking for free iron
contamination on stainless steel as a test for passivation. As for a
spot test to check for plating, investigate the spot test kits
provided by Koslow. They will probably have something that would be
easy, safe, and reliable.
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Larry Hanke
materials testing laboratory
Minneapolis, Minnesota
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I am looking for a non-toxic alternative to ferroxyl solution for
testing stainless steel which has been passivated.
Kenneth Fortune
distiller - Scotland
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Probably the simplest "non-toxic" test is the boiling distilled
water test. There are a number of varieties of this. You can see ASTM
F1089 [link is to spec at TechStreet] for a typical test.
Different industries use different times on the test. Very typical is
1 hour in boiling water, 1 hour cooldown, 1 hour in air to dry. Many
varieties of this.
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