1、BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06Metallic and other inorganic coatings - Simultaneous thickness and electrode potential determination of individual layers in multilayer nickel deposits (STEP test)BS EN 16866:2017EUROPEAN STANDARD NORME EUROPENNE EUROPI
2、SCHE NORM EN 16866 November 2017 ICS 25.220.40 English Version Metallic and other inorganic coatings - Simultaneous thickness and electrode potential determination of individual layers in multilayer nickel deposits (STEP test)Revtements mtalliques et autres revtements inorganiques - Dtermination sim
3、ultane de lpaisseur et du potentiel dlectrode de couches individuelles dans des dpts de nickel multicouches (essai STEP) Metallische und andere anorganische berzge - Schichtpotentialmessung von galvanischen Mehrfach-Nickelschichtsystemen (STEP-Test) This European Standard was approved by CEN on 11 S
4、eptember 2017. 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 b
5、e 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 responsibility of a CEN member into its own language and notified to
6、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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, I
7、reland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Man
8、agement Centre: Avenue Marnix 17, B-1000 Brussels 2017 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 16866:2017 ENational forewordThis British Standard is the UK implementation of EN 16866:2017.The UK participation in its prepara
9、tion was entrusted to Technical Committee STI/33, Electrodeposited and related coatings.A list of organizations 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
10、 its correct application. The British Standards Institution 2017 Published by BSI Standards Limited 2017ISBN 978 0 580 87902 9ICS 25.220.40Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy
11、and Strategy Committee on 30 November 2017.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARDBS EN 16866:2017EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 16866 November 2017 ICS 25.220.40 English Version Metallic and other inorganic coatings - Simultaneous thick
12、ness and electrode potential determination of individual layers in multilayer nickel deposits (STEP test)Revtements mtalliques et autres revtements inorganiques - Dtermination simultane de lpaisseur et du potentiel dlectrode de couches individuelles dans des dpts de nickel multicouches (essai STEP)
13、Metallische und andere anorganische berzge - Schichtpotentialmessung von galvanischen Mehrfach-Nickelschichtsystemen (STEP-Test) This European Standard was approved by CEN on 11 September 2017. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions f
14、or 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 CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in thr
15、ee 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 CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bo
16、dies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Sl
17、ovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2017 CEN All rights of exploitation in any form and by any means reserv
18、ed worldwide for CEN national Members. Ref. No. EN 16866:2017 EBS EN 16866:2017EN 16866:2017 (E) 2 Contents Page European foreword . 3 Introduction 3 1 Scope 5 2 Normative references 5 3 Test equipment 5 3.1 Construction of the measuring cell . 5 3.2 Composition of the test solution 6 4 Requirements
19、 . 7 5 Sampling . 7 6 Factors influencing measurement accuracy 7 6.1 Electrolyte 7 6.2 Conditioning 7 6.3 Ni deposits . 7 6.4 Surface cleanliness . 7 6.5 Measurement area and contact pressure . 7 6.6 Electrical contact . 8 6.7 Complete dissolution . 8 7 Procedure. 8 7.1 General 8 7.2 Measurement 8 7
20、.3 Evaluation 9 8 Measurement uncertainty 13 9 Test report 14 Annex A (informative) Precision data obtained by a round robin test 15 Bibliography . 16 BS EN 16866:2017EN 16866:2017 (E) 3 European foreword This document (EN 16866:2017) has been prepared by Technical Committee CEN/TC 262 “Metallic and
21、 other inorganic coatings, including for corrosion protection and corrosion testing of metals and alloys”, 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
22、May 2018, and conflicting national standards shall be withdrawn at the latest by May 2018. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights. According
23、to the CEN-CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Gree
24、ce, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 16866:2017EN 16866:2017 (E) 4 Introduction STEP test is an abbreviation for the ter
25、m “Simultaneous Thickness and Electrode Potential determination“. The STEP test can be used to measure, in one single operating step, the parameters (thickness of the individual nickel layers and the potential differences among them) relevant for the course of corrosion in a multilayer nickel system
26、 and, provided the suitable instruments be applied, to document them as well. The test is a modification of the well-known coulometric method for the measurement of the coating thickness. This method takes advantage of the fact that, following the anodic dissolution of a nickel coating, a potential
27、jump takes place whose magnitude can be measured against a reference electrode. Although, nowadays, the STEP test has been incorporated into a number of company standards, particularly in the automobile industry, so far no uniform and generally acknowledged potential difference values are available.
28、 At present, values between 80 mV and 150 mV are assumed for double nickel layers, with the semi-bright nickel layer always being nobler than the bright one. Likewise no obligatory numerical values are available, so far, regarding the potential difference between bright nickel layers and existing sp
29、ecial nickel layers (e.g. in the case of micro-porous chromium plating). According to the current practical experience, the potential difference is larger than approximately 20 mV, with the bright nickel layer always having to be less noble than the special nickel layer. BS EN 16866:2017EN 16866:201
30、7 (E) 5 1 Scope This European Standard applies to the measurement of the thickness of the individual nickel layers in electroplated multilayer nickel coatings and to the measurement of the potential differences between the individual nickel layers in electroplated multilayer nickel coatings. The mea
31、surement of coatings or layer systems other than electroplated multilayer nickel coatings is outside the scope of this European Standard. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For da
32、ted references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN ISO 2177, Metallic coatings - Measurement of coating thickness - Coulometric method by anodic dissolution (ISO 2177) EN ISO 3696, Water for ana
33、lytical laboratory use - Specification and test methods (ISO 3696) 3 Test equipment 3.1 Construction of the measuring cell Figure 1 shows two examples of the typical schematic construction of a measuring cell used for the simultaneous determination of layer thicknesses and potential differences in m
34、ultilayer nickel systems. The cells differ with regard to the implementation of the reference electrode. In Figure 1 a), the reference electrode is a silver wire coated with silver chloride and positioned at the edge of the cell; in Figure 1 b), it is a silver ring coated with silver chloride and po
35、sitioned at the bottom of the cell. With regard to measurement uncertainty, both variants provide the same result for the measurement of the potential difference and (following calibration) the measurement of the layer thickness, independent of the concrete implementation of the reference electrode.
36、 NOTE 1 The silver ring used as the reference electrode in Figure 1 b) is of advantage insofar as the adjustment of the silver wire, which would otherwise be required, becomes unnecessary, leading to results that are more exact and more reproducible. NOTE 2 The circulated volume of electrolyte solut
37、ion is typically some 0,1 ml per second. BS EN 16866:2017EN 16866:2017 (E) 6 a) Measuring cell with silver wire, coated with AgCl, used as the reference electrode b) Measuring cell with silver ring, coated with AgCl in the electrolyte-wetted area, used as the reference electrode Key 1 pump 2 measuri
38、ng instrument (with constant-current source and voltmeter) 3 reference electrode 4 electrode surface wetted with electrolyte 5 dissolving electrolyte 6 counter electrode (cathode) 7 gasket 8 working electrode (anode, measurement object with nickel layer system) Figure 1 Typical schematic constructio
39、ns of the measuring cell 3.2 Composition of the test solution Nickel(II)-chloride hexahydrate (NiCl2 6 H2O) 300 g/l Sodium chloride (NaCl) 50 g/l Boric acid (H3BO3) 25 g/l pH value 3,0 Water of grade 3 in accordance with EN ISO 3696. The pH value should be complied with as closely as possible. If re
40、quired it is adjusted by means of diluted hydrochloric acid or sodium hydroxide solution. BS EN 16866:2017EN 16866:2017 (E) 7 4 Requirements The geometry of the parts to be tested shall be such that the measuring cell can be attached to the surface in a liquid-tight way, at the respective points to
41、be measured. Prior to this, the surface to be measured shall be appropriately de-chromed and activated (e.g. in a 1:1 dilution of chemically pure, concentrated hydrochloric acid). When selecting the de-chroming and activating procedures, it shall be ensured that the nickel coating is not visibly dam
42、aged by these procedures. 5 Sampling Sampling from the ongoing production of parts should be performed in accordance with ISO 2859-1 and ISO 2859-2. The tolerable margin of error is specified by the client. 6 Factors influencing measurement accuracy 6.1 Electrolyte Each measurement shall be carried
43、out using fresh electrolyte. Used electrolytes can result in falsified measurement results. 6.2 Conditioning New reference electrodes or ones which had not been in use for an extended period of time shall be conditioned (creation of a silver chloride layer at the electrode surface) prior to use. Lac
44、k of or inadequate conditioning results in falsified or atypical courses of measurement that cannot be correctly interpreted. Any conditioning and potentially required cleaning are carried out in accordance with the instrument manufacturers information. NOTE The conditioning quality is checked on th
45、e basis of comparative measurements using reference standards of known potential differences and layer thicknesses. 6.3 Ni deposits As a result of repeated measurements, Ni is gradually deposited on the surface of the cathode. From a certain thickness on, these Ni deposits can become dissolved from
46、the cathode and move around in the electrolyte in the form of “flocs”, leading to very noisy measurement curves and a faulty evaluation. It is, therefore, necessary to remove any Ni deposits early enough from the surface of the cathode (this is done mechanically or, in the case of persistent deposit
47、s, chemically). 6.4 Surface cleanliness In order to achieve a uniform dissolution process across the whole measurement area, the surface of the test specimen shall be free from contaminations and oxide layers (see also Clause 4). 6.5 Measurement area and contact pressure Depending on the size and sh
48、ape of the test specimen different gaskets defining the measurement area can be selected. The measurement area influences the measurement uncertainty. Usually larger measurement areas result in smaller uncertainties. The contact pressure exerted on the test specimen by the measuring cell shall be su
49、fficiently high to enable a leakage-free sealing between the cell and the sample surface. Too high a pressure, on the other hand, can lead to a reduction of the active dissolution surface (increase of the sealing surface with regard to a calibration carried out beforehand), thereby causing measurement errors. When placing the measuring cell, the relevant manufacturers provisions shall be met. BS EN 16866:2017EN 16866:2017 (E) 8 6.6 Electrical contact Good contacts shall be ensured at the electrical connections of the installation. It is particu
