DIN EN 12476-2001 ENG金属磷化转化涂层方法

Notes on the use of this standard
NA.1 Chemical composition of coating
In addition to the methods specified in this annex, other analytical methods with at least the same precision may be used. The detection of phosphate in a coating shall be taken as proof that it Байду номын сангаасs a phosphate coating (cf. subclause NA.2). To establish that a coating is a manganese phosphate coating, it is sufficient to establish the presence of manganese (for ferrous substrates only) (cf. subclause NA.3). To establish that a coating is a zinc phosphate or a zinc calcium phosphate coating, it is sufficient to establish the presence of zinc or zinc and calcium, respectively (for zinc-free substrates) (cf. subclause NA.5). If neither manganese nor zinc has been detected in a phosphate coating on a substrate of ferrous material, then the coating is certain to be an iron phosphate coating.
NA.1.1 Reagents
The following reagents, of analytical grade, and distilled or deionized water should be used. a) 5 % sodium hydroxide solution, NaOH, prepared by dissolving 50 g of sodium hydroxide in one litre of water. b) 40 % nitric acid solution, HNO3, prepared by mixing four parts by volume of nitric acid (of density 1,4 g/cm³) and 2,5 parts by volume of water. c) Ammonium molybdate solution, prepared by dissolving 88,3 g of ammonium heptamolybdate tetrahydrate, (NH4)6Mo7O24 · 4 H2O, 30 ml of 25 % ammonia solution (of density 0,91 g/cm³), and 240 g of ammonium nitrate, NH4NO3, in water and making up to 1 litre. d) 25 % hydrochloric acid solution, HCl, prepared by mixing 2,5 parts by volume of hydrochloric acid (of density 1,19 g/cm³), and 1,2 parts by volume of water; e) 5 % potassium hexacyanoferrate (II) solution, K4[Fe(CN)6], prepared by dissolving 50 g potassium hexacyanoferrate in one litre of water; f) 17 % nitric acid solution, HNO3, prepared by mixing 1,7 parts by volume of nitric acid (of density 1,4 g/cm3) and 4,8 parts by volume of water. g) 3 % hydrogen peroxide solution, H2O2 (of density 1,3 g/cm3), prepared by mixing one part by volume of hydrogen peroxide and nine parts by volume of water; h) Bismuth sodium trioxide, NaBiO3. i) Ammonium nitrate, NH4NO3. j) 10 % aqueous ammonia solution, NH3, prepared by mixing two parts by volume of concentrated ammonia solution (of density 0,91g/cm³) and five parts by volume of water. k) Ammonium oxalate, (NH4)2C2O4 · H2O. l) Ammonium chloride, NH4Cl. m) 10 % hydrochloric acid solution, HCl, prepared by mixing one part by volume of hydrochloric acid (of density 1,19 g/cm3) and 2,7 parts by volume of water. n) 45 % sulfuric acid solution, H2SO4, prepared by mixing 4,5 parts by volume of sulfuric acid (of density 1,84 g/cm3) and 5,3 parts by volume of water. o) 5 % potassium permanganate solution, KMnO4, prepared by dissolving 50 g of potassium permanganate in one litre of water.
NA.2 Testing for the presence of phosphate
To test for the presence of phosphate in the coating, treat a coated test piece having a surface area of about 100 cm2 with 100 ml of a 5 % sodium hydroxide solution at 80 °C to 90 °C until either the coating has been stripped or it has at least been noticeably attacked. If necessary, scrub the coating off with a rubber wiper. Filter the resulting solution and acidify 25 ml of the filtrate with 40 % nitric acid. Add 10 ml of the ammonium molybdate solution and 5 g of ammonium nitrate to the acidified filtrate, and leave the mixture to stand for at least 15 minutes. A yellow precipitate indicates the presence of phosphate.
Previous editions DIN 50942: 1955-01, 1973-11, 1987-05, 1996-09; DIN EN 12476: 2000-07.
National Annex NA Standard referred to
(and not included in Normative references and Bibliography) DIN EN ISO 3892 Conversion coatings on metallic materials – Determination of coating mass per unit area
with gravimetric methods (ISO 3892 : 1980)
Continued on pages 2 and 3. EN comprises 12 pages.
© No part of this standard may be reproduced without the prior permission of DIN Deutsches Institut für Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany, has the exclusive right of sale for German Standards (DIN-Normen).
European Standard EN 12476 : 2000 has the status of a DIN Standard.
A comma is used as the decimal marker.
National foreword
This standard has been prepared by CEN/TC 262 ‘Metallic and other organic coatings’ (Secretariat: United Kingdom). The responsible German body involved in its preparation was the Normenausschuss Materialprüfung (Materials Testing Standards Committee), Technical Committee Chemische und elektrochemische Überzüge. The committee decided to retain the specifications of subclause 7.2 (cf. clauses NA.1 to NA.5) and of tables 7 and 8 (cf. tables NA.1 and NA.2) of DIN 50942 by introducing them in the national annex below. DIN EN ISO 3892 is the standard corresponding to European Standard EN ISO 3892 referred to in clause 2 of the EN.