磷化处理EN 12476标准(英文版)

ICS 25.220.99Phosphatierüberzüge auf Metallen – Verfahren für die Festlegung vonAnforderungen European Standard EN 12476:2000 has the status of a DIN Standard.A comma is used as the decimal marker.National forewordThis 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 (Ma-terials 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 2of the EN.AmendmentsThis standard differs from the DIN EN 12476, July 2000 edition, and DIN 50942, September 1996 edition,in that a national annex has been introduced.Previous editionsDIN 50942: 1955-01, 1973-11, 1987-05, 1996-09; DIN EN 12476: 2000-07.National Annex NAStandard referred to(and not included in Normative references and Bibliography )DIN EN ISO 3892Conversion coatings on metallic materials – Determination of coating mass per unit areawith gravimetric methods (ISO 3892:1980)Ref.No.DIN EN 12476:2001-10English price group 09Sales No.110902.02DEUTSCHE NORM October 2001EN 12476{Continued on pages 2 and 3.EN comprises 12 pages.©No part of this standard may be reproduced without the prior permission ofDIN Deutsches Institut für Normung e.V., Berlin. Beuth Verlag GmbH , 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).Phosphate conversion coatings of metalsMethod of specifying requirementsEnglish version of DIN EN 12476Supersedes DIN EN 12476,July 2000 edition, and DIN 50942, September 1996 edition.Page 2DIN EN 12476:2001-10Notes on the use of this standardNA.1Chemical composition of coatingIn 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 is 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.1.1ReagentsThe following reagents, of analytical grade, and distilled or deionized water should be used.a)5% sodium hydroxide solution, NaOH, prepared by dissolving 50g of sodium hydroxide in one litre of water.b) 40% nitric acid solution, HNO 3, prepared by mixing four parts by volume of nitric acid (of density 1,4g/cm³) and 2,5 parts by volume of water.c)Ammonium molybdate solution, prepared by dissolving 88,3g of ammonium heptamolybdate tetrahydrate, (NH 4)6Mo 7O 24·4 H 2O, 30m l of 25% ammonia solution (of density 0,91g/cm³), and 240g of ammonium nitrate, NH 4NO 3, in water and making up to 1litre.d)25% hydrochloric acid solution, HC l , prepared by mixing 2,5 parts by volume of hydrochloric acid (of density 1,19g/cm³), and 1,2 parts by volume of water;e)5% potassium hexacyanoferrate (II ) solution, K 4[Fe(CN)6], prepared by dissolving 50g potassium hexacyanoferrate in one litre of water;f)17% nitric acid solution, HNO 3, prepared by mixing 1,7 parts by volume of nitric acid (of density 1,4g/cm 3) and 4,8 parts by volume of water.g)3% hydrogen peroxide solution, H 2O 2 (of density 1,3g/cm 3), prepared by mixing one part by volume of hydrogen peroxide and nine parts by volume of water;h)Bismuth sodium trioxide, NaBiO 3.i)Ammonium nitrate, NH 4NO 3.j)10% aqueous ammonia solution, NH 3, prepared by mixing two parts by volume of concentrated ammo-nia solution (of density 0,91g/cm³) and five parts by volume of water.k)Ammonium oxalate, (NH 4)2C 2O 4 · H 2O.l)Ammonium chloride, NH 4C l .m)10% hydrochloric acid solution, HC l , prepared by mixing one part by volume of hydrochloric acid (of density 1,19g/cm 3) and 2,7 parts by volume of water.n)45% sulfuric acid solution, H 2SO 4, prepared by mixing 4,5 parts by volume of sulfuric acid (of density 1,84g/cm 3) and 5,3 parts by volume of water.o)5% potassium permanganate solution, KMnO 4, prepared by dissolving 50g of potassium permanganate in one litre of water.NA.2Testing for the presence of phosphateTo test for the presence of phosphate in the coating, treat a coated test piece having a surface area of about 100 cm 2 with 100m l 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 25m l of the filtrate with 40% nitric acid. Add 10m l of the ammonium molybdate solution and 5g 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.NA.3Testing for the presence of manganeseTo test for the presence of manganese, dissolve the filter residue obtained as described in subclause NA.2 with warm 17% nitric acid, to which a few drops of 3% hydrogen peroxide have been added. To decompose the excess hydrogen peroxide, boil the resulting solution for a few minutes and then cool it to ambient ing half of the solution, test for manganese by adding 0,5g of bismuth sodium trioxide, thus oxidizing any manganese present to permanganate; a reddish violet colour indicates the presence of manganese.Use the other half of the solution to test for the presence of calcium as described in subclause NA.5, if necessary.NA.4Testing for the presence of zincTo test for the presence of zinc (only for coatings on zinc-free substrates), use 25% hydrochloric acid to slightly acidify 25m l of the filtrate obtained as described in subclause NA.2 and then add 5m l of 5% potassium hexacyanoferrate (II ) solution. A white precipitate, which may have a slight green tinge due to the presence of a small amount of iron, indicates the presence of zinc.NA.5Testing for the presence of calciumTo test for the presence of calcium, take 5m l of the alkaline filtrate obtained as described in subclause NA.2and combine it with the remaining half of the solution obtained as described in subclause NA.3. Prepare a clear solution by adding a few drops of 17% nitric acid and then buffering it to a pH between 2 and 3 by adding a few drops of 10% ammonia solution (check the pH with special indicator paper, e.g. ion-specific indicator paper). After heating the solution to about 80°C, dissolve into it 1g of solid ammonium oxalate, thus changing the pH of the solution to between 5 and 6 (check again with indicator paper). If necessary, adjust the pH to the desired level by adding solid ammonium chloride.If calcium is present, a fine white crystalline precipitate of calcium oxalate forms when the solution is heated to 80°C. Filter off this precipitate after about 10 minutes of heating, rinse it with hot distilled water to which some ammonium oxalate (2g/l ) has been added, and then purify it by reprecipitation as follows: Redissolve the precipitate on the filter in hot 10% hydrochloric acid, heat the resulting solution to 80°C, adjusting it to a pH of between 5 and 6 by adding 10% ammonia solution; the calcium then reprecipitates as fine crystalline calcium oxalate. Filter this off after 10minutes of heating and rinse thoroughly with hot distilled water.To identify the purified white precipitate as calcium oxalate, remove it from the filter by spraying with hot distilled water, and then add about 50m l of distilled water. Add 5m l of 45% sulfuric acid to dissolve the precipitate and treat it at about 80°C by adding some drops of 5% potassium permanganate solution. De-coloration of the permanganate solution identifies the precipitate as calcium oxalate, thus indicating the pres-ence of calcium in the coating.Table NA.1:Minimum exposure times for phosphate coatings on ferrous materials withoutsupplemental coating, using the NSS type atmosphere as in ISO 9227Type of phosphate coatingZinc phosphate Manganese phosphateSymbolZnph Mnph Mass per unit area, in g/m 2Over 10Over 16Minimum exposure time, in hours 21,5Table 8:Minimum exposure times for phosphate coatings on test panels coated with standardreference oil 1), using using the NSS type atmosphere as in ISO 9227Type of phosphate coatingZinc phosphate Zinc phosphate Zinc calcium Manganese phosphatephosphate Symbol Znph ZnphZnCaph Mnph Mass per unit area, in g/m 2 5 to 10Over 105 to 15Over 16Minimum exposure time,24482436in hours 1)Information on sources of supply is obtainable from the Normenausschuss Materialprüfung (Materials Test-ing Standards Committee), Burggrafenstr. 6, 10787 Berlin, Germany.Page 3DIN EN 12476:2001-10English versionICS 25.220.99Management Centre: rue de Stassart 36, B-1050 BrusselsEuropean Committee for StandardizationComité Européen de NormalisationEuropäisches Komitee für NormungPhosphate conversion coatings of metalsMethod of specifying requirements©2000.CEN –All rights of exploitation in any form and by any means reserved worldwide for CEN national members.Ref. No. EN 12476:2000 ECouches de conversion phosphatéesdes métaux – Méthode de spécifica-tions des exigences Phosphatierüberzüge auf Metallen –Verfahren für die Festlegung von AnforderungenThis European Standard was approved by CEN on 2000-03-01.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.Up-to-date lists and bibliographical references concerning such national stand-ards may be obtained on application to the Management Centre or to any CEN member.The European Standards exist in three official versions (English, French, German).A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official versions.CEN members are the national standards bodies of Austria, Belgium, the Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy,Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland,and the United Kingdom.ÈÉËEN 12476April 2000Page2EN12476:200023333345555568101112Page3 EN12476:2000Page4EN12476:2000Page5 EN12476:2000Page6EN12476:2000。