BS EN ISO 10309:2016 pdf download – Metallic coatings — Porosity tests — Ferroxyl test 1 Scope This International Standard specifies a method of re-vealing pores or other discontinuities,when testingmetallic coatings,that are not visibly affected by ferricyanide and chloride ions during the test periodand that are cathodic to iron and steel. This method is especially useful for thick, hard chromium coatingsused for wear resistance. NOTE 1With some coating materials a very thin layer isdissolved by the sodium chloride solution during a 10 min-ute application period (see 5.2.3). The impact of such dissolution is that potential porosity, i.e. pores that have beencovered over by very thin layers, are sometimes re-exposed. Experience has shown that such potential porosity is fre-quently re-exposed during actual service. 2Normative reference The following standard contains provisions which,through reference in this text,constitute provisionsof this International Standard. At the time of publi-cation,the edition indicated was valid. All standardsare subject to revision,and parties to agreementsbased on this International Standard are encouragedto investigate the possibility of applying the most re-cent edition of the standard indicated below. Mem-bers of IEC and lSo maintain registers of currentlyvalid International Standards. lso 3696:1987,Water for analytical laboratory use —Specification and test methods. Principle Base metal ions, formed in corrosion cells at the bottom of discontinuities in metallic coatings migrate totreated test paper held in contact with the coatingsurface.The base metal ions retained on the treatedtest paper form a blue-coloured marking or spot whenthe treated paper is subsequently immersed in a sol-ution of a ferricyanide indicator solution. 4Reagents and materials 4.1Purity All chemicals used shall be of a recognized analyticalreagent grade and the water used shall be distilled ordeionized having a conductivity not greater than20 uS/cm (see lSo 3696). 4.2Preparation of the indicator solution 4.2.1Sodium chloride reagent Dissolve 50 g of sodium chloride and 1 g of a non-ionic wetting agent in 1 litre of hot (90 c) water.Dissolve 50 g of gelatin or agar in the above men-tioned hot sodium chloride solution to provide gellingproperties.The solution will then gel upon cooling, butcan be re-liquefied, for use, by heating it to 35℃.NOTE 2 variety of non-ionic wetting agents is com-mercially available. 4.2.2Ferricyanide reagent Dissolve 10 g of potassium hexacyanoferrate(ll) (pot-assium ferricyanide) in 1 litre of water. Measure thepH of the solution. If it is outside the range 6士0,2discard the solution and the reagent and obtain apurer grade of reagent. 4.3Optional equipment flat,flexible plastic sheet (template) with a...
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