Metallic and other inorganic coatings - Simultaneous thickness and electrode potential determination of individual layers in multilayer nickel deposits (STEP test)

This standard applies to electrodeposited zinc and zinc-alloy coatings on iron and steel with Cr(VI)-free passivation. The
zinc-alloy coatings contain nickel or iron as alloying agents (referred to as zinc/nickel and zinc/iron coatings, respectively).
The main purpose of the coatings or coating systems is protecting iron and steel components against corrosion.
The standard prescribes the designations to be used for the above coating systems and specifies minimum corrosion
resistances to be achieved in specified test procedures and the minimum coating thicknesses required to achieve them.

Metallische und andere anorganische Überzüge - Schichtpotentialmessung von galvanischen Mehrfach-Nickelschichtsystemen (STEP-Test)

Diese Europäische Norm gilt zur Messung der Schichtdicken der einzelnen Nickelschichten in galvanisch abgeschiedenen Mehrfach Nickelschichtsystemen sowie zur Messung der Potentialdifferenzen zwischen den einzelnen Nickelschichten in galvanisch abgeschiedenen Mehrfach Nickelschichtsystemen.
Die Messung anderer Schichten oder Schichtsysteme als galvanisch abgeschiedene Mehrfach Nickelschicht-systeme gehören nicht zum Anwendungsbereich dieser Europäischen Norm.

Revêtements métalliques et autres revêtements inorganiques - Détermination simultanée de l’épaisseur et du potentiel d’électrode de couches individuelles dans des dépôts de nickel multicouches (essai STEP)

La présente norme s’applique au mesurage de l’épaisseur des couches de nickel individuelles dans des revêtements électrolytiques de nickel multicouches, ainsi qu’au mesurage des différences de potentiel entre ces couches.
Le mesurage des revêtements ou des systèmes de couches autres que les revêtements électrolytiques de nickel multicouches est hors du domaine d’application de la présente norme.

Kovinske in druge anorganske prevleke - Istočasno določevanje debeline in potenciala elektrode posameznih plasti v večplastnih nikljevih depozitih (preskus STEP)

Ta standard se uporablja za elektrogalvanske prevleke cinka in cinkovih zlitin na železu ali jeklu s pasivizacijo brez Cr (VI). Prevleke cinka in cinkovih zlitin vsebujejo nikelj ali železo kot legirni sredstvi (imenujejo se cink-nikljeve in cink-železove prevleke). Glavni namen prevlek ali sistemov prevlek je zaščita železnih in jeklenih sestavnih delov pred korozijo. Ta standard predpisuje oznake za uporabo z zgornjimi sistemi prevlek ter določa najmanjšo korozijsko odpornost, ki jo je treba doseči v podanih preskusnih postopkih, in najmanjšo potrebno debelino prevleke.

General Information

Status
Published
Public Enquiry End Date
29-Sep-2015
Publication Date
13-Dec-2017
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
08-Dec-2017
Due Date
12-Feb-2018
Completion Date
14-Dec-2017

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.67(3Metallische und andere anorganische Überzüge - Schichtpotentialmessung von galvanischen Mehrfach-Nickelschichtsystemen (STEP-Test)Revêtements métalliques et autres revêtements inorganiques - Détermination simultanée de l’épaisseur et du potentiel d’électrode de couches individuelles dans des dépôts de nickel multicouches (essai STEP)Metallic and other inorganic coatings - Simultaneous thickness and electrode potential determination of individual layers in multilayer nickel deposits (STEP test)25.220.40Kovinske prevlekeMetallic coatingsICS:Ta slovenski standard je istoveten z:EN 16866:2017SIST EN 16866:2018en,fr,de01-januar-2018SIST EN 16866:2018SLOVENSKI

STANDARD
SIST EN 16866:2018
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16866
November
t r s y ICS
t wä t t rä v r English Version

Metallic and other inorganic coatings æ Simultaneous thickness and electrode potential determination of Revêtements métalliques et autres revêtements inorganiques æ Détermination simultanée de l 5épaisseur et du potentiel d 5électrode de couches individuelles dans des dépôts de nickel multicouches

Metallische und andere anorganische Überzüge æ Schichtpotentialmessung von galvanischen MehrfachæThis European Standard was approved by CEN on

s s September
t r s yä

egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä

translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä

CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Serbiaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey and United Kingdomä

EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels

t r s y CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN

s x z x xã t r s y ESIST EN 16866:2018
EN 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 ................................................................................................................................................... 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 7.3 Evaluation .......................................................................................................................................................... 9 8 Measurement uncertainty ........................................................................................................................ 13 9 Test report ...................................................................................................................................................... 14 Annex A (informative)

Precision data obtained by a round robin test.................................................. 15 Bibliography ................................................................................................................................................................. 16 SIST EN 16866:2018

EN 16866:2017 (E) 3 European foreword This document (EN 16866:2017) has been prepared by Technical Committee CEN/TC 262 “Metallic and 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 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 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, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 16866:2018

EN 16866:2017 (E) 4 Introduction STEP test is an abbreviation for the term “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 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 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. 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 special 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. SIST EN 16866:2018

EN 16866:2017 (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 measurement 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 dated 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 analytical 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 multilayer 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 positioned 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. 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 solution is typically some 0,1 ml per second. SIST EN 16866:2018

EN 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 measuring 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 constructions 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 required it is adjusted by means of diluted hydrochloric acid or sodium hydroxide solution. SIST EN 16866:2018

EN 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 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 damaged 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 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. Lack 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 manufacturer's information. NOTE The conditioning quality is checked on the 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 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 deposits, 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 shape 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 uncer

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