1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 4195:2011Aerospace series Paints and varnishes T e s t m e t h o d f o r d e t e r m i n a t i o n of chromate leachingBS EN 4195:2011 BRITISH STANDARDNational forewordThis
2、 British Standard is the UK implementation of EN 4195:2011. The UK participation in its preparation was entrusted to TechnicalCommittee ACE/65/-/3, Paints, Surface Finish and Protective T r e a t m e n t s f o r A e r o s p a c e P u r p o s e s f o r A e r o s p a c e P u r p o s e s .A list of org
3、anizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2012 ISBN 978 0 580 75591 0 ICS 49.040 Co
4、mpliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 January 2012.Amendments issued since publicationDate T e x t a f f e c t e dBS EN 4195:2011EUROPEAN STANDARD NOR
5、ME EUROPENNE EUROPISCHE NORM EN 4195 December 2011 ICS 49.040 English Version Aerospace series - Paints and varnishes - Test method for determination of chromate leaching Srie arospatiale - Peintures et vernis - Test de lixiviation de chromate Luft- und Raumfahrt - Beschichtungsstoffe - Chromatausla
6、ugbarkeitstest This European Standard was approved by CEN on 27 August 2011. 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 bibli
7、ographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the respons
8、ibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Gree
9、ce, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Manageme
10、nt Centre: Avenue Marnix 17, B-1000 Brussels 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 4195:2011: EBS EN 4195:2011EN 4195:2011 (E) 2 Contents Page Foreword 3 1 Scope 4 2 Normative references 4 3 Principle 4 4 Specimens a
11、nd test apparatus .4 5 Test procedure .4 6 Analysis of hexavalent chromium5 7 Test report 5 8 Designation 6 Annex A (informative) 7 A.1 Diphenylcarbazide solution 7 A.2 Phosphoric-sulphuric acid .7 A.3 Preparation of standard chromium solutions .7 A.4 Calibration for diphenylcarbazide method 7 Annex
12、 B (informative) Calculation of factor .9 BS EN 4195:2011EN 4195:2011 (E) 3 Foreword This document (EN 4195:2011) has been prepared by the Aerospace and Defence Industries Association of Europe - Standardization (ASD-STAN). After enquiries and votes carried out in accordance with the rules of this A
13、ssociation, this Standard has received the approval of the National Associations and the Official Services of the member countries of ASD, prior to its presentation to CEN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endor
14、sement, at the latest by June 2012, and conflicting national standards shall be withdrawn at the latest by June 2012. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying
15、 any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, G
16、reece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 4195:2011EN 4195:2011 (E) 4 1 Scope This European Standard defines a test procedure for the dete
17、rmination of the leaching rate of hexavalent chromium from the dry paint film of a chromate containing primer for aerospace use. The rate can be related to requirements either to prescribe the type of primer for an intended use or for the purpose of batch quality consistency. The procedure is applic
18、able to products intended for use in aerospace applications. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (
19、including any amendments) applies. EN 2090, Aerospace series - Aluminium alloy AL-P2024-T3 - Clad sheet and strip 0,3 mm a 6 mm EN 2334, Aerospace series Chromic-sulphuric acid pickle of aluminium and aluminium alloys EN ISO 3696, Water for analytical laboratory use Specification and test methods (I
20、SO 3696) 3 Principle The test involves placing a dry film of chromate primer in distilled water in accordance with EN ISO 3696 for a period of time at a controlled temperature to allow soluble chromate to leach from the film into solution in the water. The water is collected for the measurement of d
21、issolved hexavalent chromate by a suitable means. Because the rate of leaching can vary considerably over a period of time the collection time is divided into a number of periods of different duration appropriate to the rate of leaching over the collection period. Some of the water collected in the
22、collection periods is not used for measurement because normally sufficient data is gained from other collections. Values of chromate leaching can be numerically expressed or for convenience plotted on a graph. 4 Specimens and test apparatus The apparatus shall consist of a stoppered test tube to hol
23、d the water and the painted test specimens. The test tube shall be maintained at a constant temperature, as specified, in a suitably controlled chamber. Test specimens shall be of aluminium alloy EN 2090. Test specimens shall be prepared by chrome sulphuric acid pickling in accordance with EN 2334 o
24、r other non chromate leaching pretreatment as may be specified in the relevant material specification. They shall then be sprayed with primer within four hours to give the paint thickness prescribed in the relevant material specification. When dried and preconditioned as prescribed in the relevant m
25、aterial specification an area of 40 cm2shall be cut from the panel for leaching test immersion. All edges shall be uncoated. Using a test tube for the immersion, it is convenient to cut two panels of dimensions (10 2) cm. This assumes that the panels are coated on one side only and are then placed b
26、ack to back in the test tube. 5 Test procedure A test specimen, prepared as above, shall be totally immersed in a stoppered tube containing 50 ml of distilled water maintained at a temperature of (40 2) C. BS EN 4195:2011EN 4195:2011 (E) 5 The distilled water shall be renewed after 1, 2, 3, 4, 7, 10
27、, 14, 18, 23, 29 and 36 days. The samples collected at the end of 2, 10 and 36 days only shall be analysed for chromate content as normally this is sufficient to determine the leach rate characteristics of the paint sample under test. However samples from other collection periods can also be measure
28、d if additional data is required. At the end of the appropriate immersion time, the water in which the painted specimens have been immersed shall be poured into a 100 ml volumetric flask. The specimen and the test container shall be rinsed with a volume of distilled water not exceeding 25 ml and thi
29、s shall be added to the volumetric flask containing the first solution. Another 50 ml of distilled water shall be added to the original container to proceed with the test for the next immersion period. A suitable method of analysis for chromate determination has been outlined in Annex A. Whether thi
30、s or another method is employed for chromate concentration determination, the final volume of chromate containing solution, tube washings and reagents shall be 100 ml. The concentration of hexavalent chromium in the solution shall be measured and calculated as milligrams of chromate leached per squa
31、re decimetre of paint film. 6 Analysis of hexavalent chromium A sample shall be taken from the 100 ml container and analysed for hexavalent chromium content. The result shall be determined as mg Cr per l and expressed as mg CrO42-per dm2of paint film tested. NOTE For a 40 cm2exposed primer area this
32、 involves multiplying the quantity of hexavalent chromium in mg/l by a factor of 0,557 7. Details of the calculation of the factor for this case are given in Annex B. The quantity of CrO42-per dm2shall be converted into CrO42-per dm2per day leaching rate. This means that the value calculated for the
33、 test sample needs to be divided by the number of days over which the paint sample had been in contact with that sample of water since it had been previously renewed. Sample at 2 days duration 1 d to 2 d divide by 1 Sample at 10 days duration 7 d to 10 d divide by 3 Sample at 36 days duration 29 d t
34、o 36 d divide by 7 The results can be numerically expressed or for convenience can be plotted on a semi-logarithmic graph. 7 Test report The test report shall contain at least the following information: a) Complete identification of the paint used including suppliers code numbers, date of manufactur
35、e, batch number, material standard, etc.; b) Reference to this European Standard (EN 4195); c) The number of specimens tested; d) The paint thickness applied; e) Dimensions of specimen tested; f) The overall drying time between application and testing; BS EN 4195:2011EN 4195:2011 (E) 6 g) The method
36、 of analysis of chromate used for the determination; h) Date of test and traceability to individuals performing the test work; i) Any incident which may have affected the results and any deviation from the test method; j) Reference to the material standard; k) The test results. 8 Designation EXAMPLE
37、 Description block DETERMINATION OF CHROMATE LEACHING Identity block EN4195 Number of this standard BS EN 4195:2011EN 4195:2011 (E) 7 Annex A (informative) NOTE The following is one of many methods used for determining chromate concentration in a solution. It uses a colormetric determination of diph
38、enylcarbazide complex. A set of standard solutions are prepared with increasing chromium concentrations and are used to construct a suitable calibration curve. The concentration of chromium in the “unknown” solution can then be read off the graph. A.1 Diphenylcarbazide solution 40 g of phthalic anhy
39、dride shall be dissolved in 1 l of hot industrial ethyl alcohol The solution shall be cooled and 5 g of diphenylcarbazide added. This shall be stirred with a magnetic stirrer to dissolve. A.2 Phosphoric-sulphuric acid 375 ml of concentrated sulphuric acid (S.G. = 1,84 g/cm3) and 375 ml of concentrat
40、ed phosphoric acid (S.G. = 1,83 g/cm3) shall be added to 1 l of distilled water. A.3 Preparation of standard chromium solutions 2,828 g of dried “Analar” potassium dichromate shall be accurately weighed, dissolved in about 100 ml of distilled water and diluted to 1 l in a volumetric flask. This solu
41、tion shall now contain 1 g/l (or 1 000 g/ml) of chromium. In order to obtain a solution containing 5 g/ml of chromium, 5 ml of the 1 g/l solution shall be pipetted into a 1 l volumetric flask and made up to the mark with distilled water. In obtain a solution containing 100 g/ml of chromium, 50 ml of
42、 the 1 g/l solution shall be pipetted into a 500 ml volumetric flask and made up to the mark with distilled water. NOTE Standard solutions prepared in this way are stable when stored in closed glass containers for a maximum of 12 months. A.4 Calibration for diphenylcarbazide method Using a burette,
43、2, 5, 10, 15 and 20 ml of 5 g/ml standard solution shall be put into respective volumetric flasks. NOTE 1 This is equivalent to 10, 25, 50, 75 and 100 g of chromium for calibration. 50 ml of distilled water shall be added to another 100 ml volumetric flask. This shall be used as a blank. The volume
44、of solution in each flask shall be made up to approximately 50 ml with distilled water. 10 ml of the phosphoric/sulphuric acid solution and 10 ml of diphenylcarbazide shall be added. The solutions shall be made up to the mark with distilled water, thoroughly mixed and allowed to stand for 10 minutes
45、. The standards shall be poured into 1 cm cells, the optical density values shall be measured using the blanks a reference on a suitable spectrophotometer set at a wavelength of 540 nm. BS EN 4195:2011EN 4195:2011 (E) 8 A graph of optical density versus chromium content of standards shall be plotted
46、. For test samples the steps outlined in clauses 3 to 5 of this section shall be followed and the chromium content equivalent to the measured optical density shall be read from the calibration graph. NOTE 2 A fresh graph must be produced daily or with each batch of samples. BS EN 4195:2011EN 4195:20
47、11 (E) 9 Annex B (informative) Calculation of factor The result shall be determined as mg Cr per l and expressed as mg CrO4 per dm2of paint film tested. NOTE For a 40 cm2exposed primer area this involves multiplying the quantity of hexavalent chromium in mg/l by a factor of 0,557 7. Mol wt of CrO4a
48、115,994 8 Atomic wt of Cr b 51,996 mg Cr per l Y mg Cr per 100 ml Y/10 mg CrO4per 100 ml Y a/b/10 0,223 084 For 40 cm2Y a/b/10 0,223 084 For 1 cm2Y a/b/10/40 0,005 577 For 100 cm2 = 1 dm2Y a/b/10/40 100 0,557 7 This page deliberately left blankThis page deliberately left blankBSI is the independent
49、national body responsible for preparing British Standardsand other standards-related publications, information and services. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter.British Standards Institution (BSI)raising standards worldwideBSI Group Headquarters389 Chiswick High Road London W4 4AL UKTel +44 (0)20 8996 9001Fax +44 (0)20 8996 Standards are updated by amendment or revision. Users of British Stan-dards should make sure that t
