DIN EN 12476-2000 金属磷酸盐转化膜 制定要求的方法 英文版

DEUTSCHE NORM October 2001 Phosphate conversion coatings of metals Method of specifying requirements English version of DIN EN 12476 DIN EN 12476 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 tetain 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. Amendments This 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 editions DIN 50942: 1955-01, 1973-11, 1987-05, 1996-09; DIN EN 12476: 2000-07. National Annex NA Standard referred to (and not include 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. Page 2 DIN EN 12476: 2001-10 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 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 of zinc calcium phosphate coatings, 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 b dissolving 88.3g of ammonium heptamolybdate tetrahydrate, (NH4)6Mo7O24·4H2O,30 ML OF 25 % ammonia solution (of density 0.91g/cm3), and 240g 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 1.19g/cm3), and 1.2 parts by volume of water; e) 5% potassium hexacyanoferrate (II) solution, K4[FE(CN)6], prepared by dissolving 50g 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 1.4g/cm3) and 4.8 parts by volume of water; g) 3% hydrogen peroxide solution, H2O2 (of density 1.3g/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 0.9g/cm3) and five parts by volume of water. k) Ammonium oxalate (NH4)2C2O4 ·H20; l) Ammonium chloride, NH4Cl; m) 10% hydrochloric acid solution, HCl, prepared by mixing one part by volume of hydrochloric acid (of density 1.19g/cm3) and 2.7parts by volume of water; n) 45% sulfuric acid solution, H2SO4, prepared by mixing 4.5 parts by volume of sulfuric acid (of density 1.84g/cm3) and 5.3 parts by volume of water; o) 5% potassium permanganate solution,KMnO4, prepared by dissolving 50g 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 100ml of a 5%sodium hydroxide solution at 80℃ to 90 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 25ml of the filtrate with 40% metric acid. Add 10ml 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.3 Testing for the presence of manganese To 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 temperature. Using half of the solution, test for manganese by adding 0.5g of bismuth trioxide, thus oxidizing any manganese present to permanganate; a reddish violet colout 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. Page 3 DIN EN 12476:2001-10 NA.4 Test for the presence of zinc To test for the presence of zinc (only for coatings on zinc-free substrates), use 25% hydrochloric acid to slightly acidify 25ml of the filtrate obtained as described in subclause NA.2 and then add 5ml 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.5 Testing for the presence of calcium To test for the presence of calcium, take 5ml of the alkaline filtrate obtained as described in subclause NA.2 and 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 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℃,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℃. 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 ℃, 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 10 minutes 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 50ml of distilled water. Add 5ml of 45% sulfuric acid to dissolve the precipitate and treat it at about 80 ℃ by adding some drops of 5% potassium permanganate solution. Decoloration of the permanganate solution identifies the precipitate ad calcium oxalate, thus indicating the presence of calcium in the coating. Table NA.1: Minimum exposure times for phosphate coatings on ferrous materials without supplemental coating, using the NSS type atmosphere as in ISO 9227 Type of phosphate coating Zinc phosphate Manganese phosphate Symbol Znph Mnph Mass per unit area, in g/m2 Over 10 Over 16 Minimum exposure time, in hours 2 1.5 Table 8: minimum exposure times for phosphate coatings on test panels coated with standard reference oil1), using the NSS type atmosphere as in ISO 9227 Type of phosphate coating Zinc phosphate Zinc phosphate Zinc calcium phosphate Manganese phosphate Symbol Znph Znph ZnCaph Mnph Mass per unit area, in g/m2 5 to 10 Over 10 5 to 15 Over 16 Minimum exposure time, in hours 24 48 24 36 1) Information on sources of supply is obtainable from the Normenausschuss Materialprüfung (materials Testing Standards Committee), Burggrafenstr. 6, 10787 Berlin, Germany. ICS 25.220.99 English version Phosphate conversion coatings of metals Method of specifying requirements This 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 standards 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, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom CEN European Committee for Standardization Comité Européen de Normalisation Europäisches Komitee für Normung Management Centre:rue de Stassart 36, B-1050 Brussels © 2000. CEN – All rights of exploitation in any form and by any means Reserved worldwide for CEN national members. EUROPEAN STANDARD NORME EUROPéENNE EUROPäISCHE NORM EN 12476 April 2000 Couches de conversion phosphatées des métaux – Méthode de specifica - tions des exigences Phosphatierüberzüge auf Metallen – Verfahren für die Festlegung von Anforderungen Ref. No. EN 12476 : 2000 E Page 2 EN 12476 : 2000 CONTENTS Page Foreword …………………………………………………………………………………………………………………… 2 1 Scope ……………………….……………………………………….……………………………………………. 3 2 Normative references ………………………………………………………………………………...………… 3 3 Information to be supplied by the purchaser …………………………………………………………… 3 4 Coating types and designation ……………………………………………………………………………… 3 4.1 Coating types ……………………………………………………………………………………………………… 3 4.2 Conversion coating designation ………………………………………………………………………………. 4 5 Sampling ……………………………………………………………………………………………………………. 5 6 Coating requirements …………………………………………………………………………………………….. 5 6.1 Appearance ………………………………………………………………………………………………………… 5 6.2 Coating mass per unit area ……………………………………………………………………………………… 5 6.3 Corrosion resistance …………………………………………………………………………………………….. 5 Annex A (informative) Guidance ………………………………………………………………………………………… 6 Annex B (informative) Recommendations …………………………………………………………………………….. 8 Annex C (normative) After treatment …………………………………………………………………………………… 10 Annex D (normative) Determination of corrosion resistance ……………………………………………………… 11 Bibliography ………………………………………………………………………………………………………………… 12 Foreword This European Standard has been prepared by Technical Committee CEN/TC 262 “Metallic and other inorganic coatings”, the secretariat of which is held by BSI. This /European /standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by October 2000, and conflicting national standards shall be withdrawn at the latest y October 2000. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Page 3 EN 12476 : 2000 1 Scope This European Standard specifies a method of specifying requirements for phosphate conversion coatings, intended primarily for application to ferrous metals, aluminium, zinc, cadmium and their alloys (see annex A). 2 Normative references This European Standard incorporates by dated and undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments). EN ISO 3892, Conversion coatings on metallic materials ---Determination of coating mass per unit area --- Gravimetric methods (ISO 3892 : 1980). ISO 4519, Electrodeposited metallic coatings and related finishes --- Sampling procedures for inspection by attributes. ISO 9227, Corrosion tests in artificial atmospheres --- Salt spray tests. 3 Information to be supplied by the purchaser The following information shall be supplied by the purchaser: a) the coating designation (see clause 4); b) any necessary heat treatment for parts that might be subject to failure from the effects of hydrogen induced during the preparation or phosphating processes (see notes 1 and 2); c) sampling methods, acceptance levels or any other inspection requirements, if different from those given in ISO 4519 (see clause 5); d) the surface preparation prior to phosphate conversion coating (see A.2); e) the surface appearance (see 6.1); f) corrosion resistance (see 6.3); g) the nature, condition and finish of the basis metal, if any of these could affect the serviceability and/or the appearance of the coating. NOTE 1 Heat treatment procedures and classes are specified in ISO 9587 for stress relieving before processing and in ISO 9588 for embrittlement relief after processing, but other conditions may be specified by the purchaser provided that they can be shown to be effective. NOTE 2 Heat treatment in accordance with the recommended conditions can never guarantee complete freedom from hydrogen embrittlement and tests should be specified whenever possible. Freedom from failure of test samples will enable a degree of confidence in the procedure to be demonstrated depending on the size of the sample tested. 4 Coating types and designation 4.1 Coating types The conversion coating shall be described in accordance with table 1. NOTE Annex B provides guidance on coating type, purpose, end use and mass per unit area. Page 4 EN 12476 : 2000 Table 1 --- Principle types of phosphate conversion coatings Coating type Symbol Zinc phosphate Znph Zinc-calcium phosphate ZnCaph Manganese phosphate Mnph Iron phosphate (produced by alkali-metal phosphate treatment) Feph NOTE Other coating types exist including zinc phosphate modified with iron and/or nickel and/or manganese. The modifying metal will normally be present in the form of a double salt such as Zn2Me(PO4)2·4H2O, where Me represents Fe(II), Ni or Mn. Zn remains the main metal constituent of these coating which, to avoid confusion, have not been given separate symbols. It should also be noted that metal from the substrate material will often be incorporated in the conversion coating. 4.2 Conversion coating designation The conversion coating designation shall comprise the following: a) the number of this European Standard; b) a hyphen; c) the basis metal code, e.g. its chemical symbol )or that of the principal constituent of an alloy) (see note 1); d) a solidus; e) a symbol describing the type of coating (see table 1); f) a solidus; g) a symbol indicating the function of the conversion coating, as follows: r = adhesion and/or corrosion protection; z = to facilitate cold forming; g = to facilitate sliding action; e = electrical insulation; h) a solidus; i) a number indicating the coating mass per unit area, in grams per square metre, with a tolerance of ± 30%. If the phosphate conversion coating has to be after-treated, the designation shall also comprise the following; a) a solidus; b) a symbol indicating any after-treatment of the conversion coating, as specified in table C.1 (see note 2). NOTE 1 It is recommended that the chemical symbol is followed by the standard designation of the basis metal. NOTE 2 This can be repeated if more after-treatments are required. EXAMPLE Designation of a zinc phosphate type coating (Znph) applied to ferrous metal (Fe) to give corrosion protection ® at a mass per unit area of 3g/m2 ± 0.9 g/m2 (3) and for which the after-treatments are sealing (T2) and painting (T1) Phosphate conversion coating EN 12476-Fe/Znph/r/T2/T1 Page 5 EN 12476 : 2000 5 Sampling Sampling shall either be in accordance with ISO 4519 or as specified by the purchaser (see 3, c). 6 Coating requirements 6.1 Appearance Zinc phosphate, zinc calcium phosphate and manganese phosphate coatings shall cover the metal surface evenly and shall not exhibit any white patches, corrosion products or finger marks. NOTE Slight fluctuations in the appearance of phosphate coatings, which may be caused by differences in the structure of the substrate, by contact with the supports or by contact with other components whilst in the phosphating drum, should not give grounds for complaint. 6.2 Coating mass per unit area The coating mass per unit area shall be determined in accordance with the appropriate method specified in EN ISO 3892. NOTE For quality assurance purposes, instruments which are available and which give a direct reading of coating mass per unit area my be used. It is , however, essential that they be calibrated against standard coatings having a coating mass per unit area of the same order as those being inspected. 6.3 Corrosion resistance When the function of the phosphate conversion coating is corrosion resistance, an after-treatment is always required. The corrosion resistance shall be determined by subjecting the after-treated parts to the accelerated corrosion test specified by the purchaser (see 3, f). If no test is specified, the parts shall be tested in accordance with the neutral salt spray (NSS) test described in ISO 9227 (see annex D). Minimum exposure times specified by the purchaser shall be attained by the test parts before the first evidence of corrosion appears. Page 6 EN 12476 : 2000 Annex A (Informative) Guidance A.1 General Phosphate conversion coatings are produced by treatment with solutions, the main constituents of which are the appropriate dihydrogen orthophosphates shown in table A.1. These coatings are applied principally to ferrous materials, aluminium, aluminium, zinc and cadmium and differ in coating mass per unit area and apparent density, depending on a) the construction material and surface condition of the components;