Metallic and other inorganic coatings - Chromate conversion coatings on zinc, cadmium, aluminium-zinc alloys and zinc-aluminium alloys - Test methods (ISO 3613:2021)

This document specifies methods for the determination of
— the presence of colourless chromate conversion coatings,
— the presence of hexavalent chromium in colourless and coloured coatings on zinc or cadmium or
aluminium-zinc (mass fraction of aluminium: 55 %, within a range of 54 % to 56 % mass fraction)
and zinc-aluminium (mass fraction of aluminium: 5 %) alloys,
— the total chromium content per unit area on zinc and cadmium,
— the mass per unit area of both colourless and coloured coatings,
— the satisfactory adhesion of chromate conversion coatings, and
— the quality of chromate coatings.
These methods are applicable to
— colourless and coloured chromate conversion coatings containing trivalent and hexavalent
chromium in varying proportions and produced by either chemical or electrochemical processes,
and
— chromate coatings that are free from any supplementary coatings, such as oil, water or solventbased
polymers or wax.

Metallische und andere anorganische Überzüge - Chromatierüberzüge auf Zink, Cadmium, Aluminium-Zink- und Zink-Aluminium-Legierungen - Prüfverfahren (ISO 3613:2021)

Dieses Dokument legt Verfahren fest zur Bestimmung:
- der Anwesenheit farbloser Chromatierüberzüge;
- der Anwesenheit von sechswertigem Chrom in farblosen und farbigen Überzügen auf Zink oder Cadmium oder Legierungen aus Aluminium-Zink (mit einem Massenanteil von 55 % Aluminium in einem Bereich von 54 % bis 56 % Massenanteil) und aus Zink-Aluminium (mit einem Massenanteil von 5 % Aluminium);
- des Gesamtchromgehalts je Flächeneinheit auf Zink und Cadmium;
- der flächenbezogenen Masse farbloser und farbiger Überzüge;
- der zufriedenstellenden Haftfestigkeit von Chromatierüberzügen; und
- der Qualität von Chromatierüberzügen.
Diese Verfahren sind anwendbar
- auf farblose und farbige Chromatierüberzüge, die dreiwertiges und sechswertiges Chrom in veränder-lichen Anteilen enthalten und durch chemische oder elektrochemische Verfahren erzeugt wurden, und
- nur auf Chromatierüberzüge, die frei von weiteren Schichten sind, wie Öl, in Wasser oder Lösungsmittel gelösten Polymeren oder Wachs.

Revêtements métalliques et autres revêtements inorganiques - Couches de conversion au chromate sur zinc, cadmium et alliages d'aluminium-zinc et de zinc-aluminium - Méthodes d'essai (ISO 3613:2021)

Kovinske in druge anorganske prevleke - S kromanjem nanesene plasti na cinku, kadmiju, zlitinah aluminij-cink in cink-aluminij - Metode preskušanja (ISO 3613:2021)

General Information

Status
Published
Public Enquiry End Date
09-Sep-2020
Publication Date
03-Jun-2021
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
03-Jun-2021
Due Date
08-Aug-2021
Completion Date
04-Jun-2021

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SLOVENSKI STANDARD
SIST EN ISO 3613:2021
01-julij-2021
Nadomešča:
SIST EN ISO 3613:2011
Kovinske in druge anorganske prevleke - S kromanjem nanesene plasti na cinku,
kadmiju, zlitinah aluminij-cink in cink-aluminij - Metode preskušanja (ISO
3613:2021)

Metallic and other inorganic coatings - Chromate conversion coatings on zinc, cadmium,

aluminium-zinc alloys and zinc-aluminium alloys - Test methods (ISO 3613:2021)
Metallische und andere anorganische Überzüge - Chromatierüberzüge auf Zink,
Cadmium, Aluminium-Zink- und Zink-Aluminium-Legierungen - Prüfverfahren (ISO
3613:2021)

Revêtements métalliques et autres revêtements inorganiques - Couches de conversion

au chromate sur zinc, cadmium et alliages d'aluminium-zinc et de zinc-aluminium -

Méthodes d'essai (ISO 3613:2021)
Ta slovenski standard je istoveten z: EN ISO 3613:2021
ICS:
25.220.20 Površinska obdelava Surface treatment
SIST EN ISO 3613:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN ISO 3613:2021
---------------------- Page: 2 ----------------------
SIST EN ISO 3613:2021
EN ISO 3613
EUROPEAN STANDARD
NORME EUROPÉENNE
May 2021
EUROPÄISCHE NORM
ICS 25.220.20 Supersedes EN ISO 3613:2010
English Version
Metallic and other inorganic coatings - Chromate
conversion coatings on zinc, cadmium, aluminium-zinc
alloys and zinc-aluminium alloys - Test methods (ISO
3613:2021)

Revêtements métalliques et autres revêtements Metallische und andere anorganische Überzüge -

inorganiques - Couches de conversion au chromate sur Chromatierüberzüge auf Zink, Cadmium, Aluminium-

zinc, cadmium et alliages d'aluminium-zinc et de zinc- Zink- und Zink-Aluminium-Legierungen -

aluminium - Méthodes d'essai (ISO 3613:2021) Prüfverfahren (ISO 3613:2021)
This European Standard was approved by CEN on 9 May 2021.

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 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 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, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 3613:2021 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN ISO 3613:2021
EN ISO 3613:2021 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

---------------------- Page: 4 ----------------------
SIST EN ISO 3613:2021
EN ISO 3613:2021 (E)
European foreword

This document (EN ISO 3613:2021) has been prepared by Technical Committee ISO/TC 107 "Metallic

and other inorganic coatings" in collaboration with 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 November 2021, and conflicting national standards

shall be withdrawn at the latest by November 2021.

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.

This document supersedes EN ISO 3613:2010.

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, Greece, Hungary, Iceland,

Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 3613:2021 has been approved by CEN as EN ISO 3613:2021 without any modification.

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SIST EN ISO 3613:2021
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SIST EN ISO 3613:2021
INTERNATIONAL ISO
STANDARD 3613
Fourth edition
2021-05
Metallic and other inorganic
coatings — Chromate conversion
coatings on zinc, cadmium,
aluminium-zinc alloys and zinc-
aluminium alloys — Test methods
Revêtements métalliques et autres revêtements inorganiques —
Couches de conversion au chromate sur zinc, cadmium et alliages
d'aluminium-zinc et de zinc-aluminium — Méthodes d'essai
Reference number
ISO 3613:2021(E)
ISO 2021
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SIST EN ISO 3613:2021
ISO 3613:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 3613:2021
ISO 3613:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Reagents ........................................................................................................................................................................................................................ 2

5 Apparatus ..................................................................................................................................................................................................................... 3

6 Test methods ............................................................................................................................................................................................................. 4

6.1 General ........................................................................................................................................................................................................... 4

6.2 Test for the presence of a colourless chromate coating on zinc ................................................................... 4

6.3 Test for the presence of a colourless chromate coating on zinc and cadmium ............................... 4

6.4 Test for the presence of a colourless chromate coating on zinc-aluminium (mass

fraction of aluminium: 5 %) alloys ........................................................................................................................................ 5

6.5 Test for the presence of hexavalent chromium in both colourless and coloured

chromate coatings ................................................................................................................................................................................ 5

6.5.1 General...................................................................................................................................................................................... 5

6.5.2 Test method employing test solution C 1 ................................................................................................... 5

6.5.3 Test method employing alternative test solution C 2 (destructive) .................................... 5

6.5.4 Expression of results .................................................................................................................................................... 7

6.5.5 Calibration of spectrophotometer .................................................................................................................... 7

6.6 Determination of hexavalent chromium content of coloured chromate coatings ........................ 8

6.6.1 Preparation of calibration graph ........................................................................................................................ 8

6.6.2 Blank test ................................................................................................................................................................................ 8

6.6.3 Determination .................................................................................................................................................................... 8

6.6.4 Expression of results .................................................................................................................................................... 8

6.7 Determination of total chromium content of coloured chromate coatings ........................................ 9

6.7.1 Preparation of calibration graph ........................................................................................................................ 9

6.7.2 Blank test ................................................................................................................................................................................ 9

6.7.3 Determination .................................................................................................................................................................... 9

6.7.4 Expression of results .................................................................................................................................................... 9

6.8 Determination of mass per unit area of both colourless and coloured chromate

coatings by gravimetric method .............................................................................................................................................. 9

6.9 Test for adhesion by abrasion .................................................................................................................................................... 9

6.10 Quality evaluation test of chromate layers on zinc and cadmium surfaces .....................................10

7 Test report ................................................................................................................................................................................................................10

Bibliography .............................................................................................................................................................................................................................11

© ISO 2021 – All rights reserved iii
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SIST EN ISO 3613:2021
ISO 3613:2021(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coatings,

in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/

TC 262, Metallic and other inorganic coatings, including for corrosion protection and corrosion testing of

metals and alloys, in accordance with the Agreement on technical cooperation between ISO and CEN

(Vienna Agreement).

This fourth edition cancels and replaces the third edition (ISO 3613:2010), which has been technically

revised. The main changes compared with the previous edition are as follows:
— Table 1 has been revised;

— analysis method described in 6.5 was aligned with the method described in IEC 62321-7-1;

— procedure for the preparation of test solution C 2 in 4.3.2 has been revised and a second standard

solution has been added;
— limiting time has been amended in 6.1;
— procedure for testing with test solution C 2 has been revised in 6.5.2;
— description of the calibration of spectrophotometer has been added.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved
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SIST EN ISO 3613:2021
ISO 3613:2021(E)
Introduction

This document specifies methods for the qualitative determination of the presence of chromate

conversion coatings as well as the total chromium content of chromate conversion coatings.

The application of very thin, colourless, practically invisible chromate conversion coatings is frequently

called “passivation”, while the application of thicker, coloured chromate conversion coatings is called

“chromating”. The term “passivation” is not correct, as it does not conform to the ISO 2080 designation,

and is therefore deprecated.

Chromate conversion coatings are based on a solution containing Cr(VI). Both the process solution and

the coating contain hexavalent chromium. The term passivation is nowadays often used for Cr(VI)-free

coatings replacing chromate conversion coatings. Products containing Cr(VI) are not allowed within

EU and processes using Cr(VI) are strictly regulated.
© ISO 2021 – All rights reserved v
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SIST EN ISO 3613:2021
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SIST EN ISO 3613:2021
INTERNATIONAL STANDARD ISO 3613:2021(E)
Metallic and other inorganic coatings — Chromate
conversion coatings on zinc, cadmium, aluminium-zinc
alloys and zinc-aluminium alloys — Test methods

WARNING — This document calls for the use of substances and/or procedures that can be injurious

to health if adequate safety measures are not taken. This document does not address any health

hazards, safety or environmental matters associated with its use. It is the responsibility of the

user of this document to establish appropriate health, safety and environmentally acceptable

practices and take suitable actions for any national and international regulations.

1 Scope
This document specifies methods for the determination of
— the presence of colourless chromate conversion coatings,

— the presence of hexavalent chromium in colourless and coloured coatings on zinc or cadmium or

aluminium-zinc (mass fraction of aluminium: 55 %, within a range of 54 % to 56 % mass fraction)

and zinc-aluminium (mass fraction of aluminium: 5 %) alloys,
— the total chromium content per unit area on zinc and cadmium,
— the mass per unit area of both colourless and coloured coatings,
— the satisfactory adhesion of chromate conversion coatings, and
— the quality of chromate coatings.
These methods are applicable to

— colourless and coloured chromate conversion coatings containing trivalent and hexavalent

chromium in varying proportions and produced by either chemical or electrochemical processes,

and

— chromate coatings that are free from any supplementary coatings, such as oil, water or solvent-

based polymers or wax.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 3892, Conversion coatings on metallic materials — Determination of coating mass per unit area —

Gravimetric methods

ISO 4520, Chromate conversion coatings on electroplated zinc and cadmium coatings

IEC 60068-2-30, Environmental testing — Part 2-30: Tests — Test Db: Damp heat, cyclic (12 h + 12 h cycle)

3 Terms and definitions
No terms and definitions are listed in this document.
© ISO 2021 – All rights reserved 1
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SIST EN ISO 3613:2021
ISO 3613:2021(E)

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Reagents

Use only reagents of recognized analytical grade and distilled water or water of equivalent purity,

unless otherwise specified, for analysis.
4.1 Test solution A (see 6.2).

Dissolve 1 g of diphenylcarbazide in a mixture of 20 ml of acetone, 60 ml of glacial acetic acid and 40 ml

of distilled water contained in a beaker. Add 15 ml of concentrated hydrochloric acid (ρ = 1,18 g/cm ),

stir and add slowly 30 ml of sodium hypochlorite solution (10 % to 15 % available chlorine). Add 5 ml

of hydrogen peroxide (30 % volume fraction) slowly with continuous stirring. Leave the solution in the

open beaker for 24 h in a fume cupboard, to allow excess chlorine to escape, before use.

The solution does not deteriorate with age and can be kept in a bottle with a loosely fitted stopper.

However, there can be losses due to evaporation and the concentration can alter so it is discarded after

six months.
4.2 Test solution B (see 6.3).

Dissolve 50 g of lead acetate trihydrate [(CH COO) Pb⋅3H O] in 1 l of distilled water or water of

3 2 2

equivalent purity. Ensure that the pH of the solution is between 5,5 and 6,8 as prepared. If the pH of the

solution is outside this range, discard the solution and obtain a new supply of lead acetate.

Any white precipitate formed during the initial preparation of the solution may be dissolved by small

additions of glacial acetic acid, provided that the pH is not reduced to a value below 5,5. Discard the

stock solution if the white precipitate does not disappear.
4.3 Test solution C (see 6.5).
4.3.1 Test solution C 1.

Dissolve 0,4 g of diphenylcarbazide in a mixture of 20 ml of acetone and 20 ml of ethanol (96 %). After

dissolution, add 20 ml of 75 % orthophosphoric acid solution and 20 ml of distilled water. Prepare this

solution not more than 8 h prior to use.
4.3.2 Test solution C 2.

Add 700 ml of orthophosphoric acid, of specific gravity 1,7, to 250 ml of distilled water or water of

equivalent purity and make up to 1 000 ml.

Dissolve 0,5 g of 1,5-diphenylcarbazide of analytical reagent grade in 50 ml of acetone of analytical

reagent grade. Dilute slowly, while stirring, with 50 ml of distilled water or water of equivalent purity

(rapid mixing can result in precipitation of diphenylcarbazide). Keep the solution in a dark glass bottle in

the refrigerator. The solution shall be discarded after four weeks or earlier when the solution becomes

discoloured.

For the Cr(VI) stock solution, dissolve 0,113 g of K Cr O of analytical reagent grade (dried for 1 h at

2 2 7

100 °C before use) in distilled water or water of equivalent purity and make up to the mark in a 1 000 ml

volumetric flask. The solution shall be discarded after nine months.
From this stock solution, prepare two Cr(VI) standard solutions.
2 © ISO 2021 – All rights reserved
---------------------- Page: 14 ----------------------
SIST EN ISO 3613:2021
ISO 3613:2021(E)

For 0,10 µg/ml Cr(VI): Measure 2,5 ml of this solution into a second 1 000 ml volumetric flask and make

up to the mark. 1 ml of this standard solution contains 0,10 µg of Cr(VI).

For 0,13 µg/ml Cr(VI): Measure 3,3 ml of this solution into a third 1 000 ml volumetric flask and make

up to the mark. 1 ml of this standard solution contains 0,13 µg of Cr(VI).

For the preparation of the comparison solution for 0,10 µg/cm Cr(VI), add 1 ml of orthophosphoric

acid and 1 ml of diphenylcarbazide solution to 50 ml of the standard Cr(VI) solution solution with

0,10 µg/ml Cr(VI) and mix thoroughly. Then add 2 ml of the diphenylcarbazide solution and mix. Allow

the solution to stand for 10 min for the colour reaction to be completed.

For the preparation of the comparison solution for 0,13 µg/cm Cr(VI), add 1 ml of orthophosphoric

acid to 50 ml of the standard Cr(VI) solution with 0,13 µg/ml Cr(VI) and mix thoroughly. Then add 2 ml

of the diphenylcarbazide solution and mix. Allow the solution to stand for 10 min for the colour reaction

to be completed.
4.4 Test solution D (see 6.6 and 6.7).

Dissolve 0,50 g of diphenylcarbazide in 50 ml of acetone. Dilute slowly, while stirring, with 50 ml of

water (rapid mixing can result in precipitation of diphenylcarbazide).

For maximum stability, store the solution under refrigeration in an amber-coloured glass bottle.

4.5 Sulfuric acid, diluted 1 + 3.

Slowly add one volume of concentrated sulfuric acid (ρ = 1,84 g/cm ) to three volumes of water.

4.6 Ammonium persulfate [(NH ) S O ].
4 2 2 8
4.7 Sodium hydroxide (NaOH), 240 g/l solution.
4.8 Silver nitrate (AgNO ), 17 g/l solution.
4.9 Potassium dichromate (K Cr O ), standard solution.
2 2 7

Dilute 2 ml of standard volumetric potassium dichromate solution (4,9 g/l) to 1 000 ml.

4.10 Phosphate buffer solution.

Dissolve 55 g of sodium dihydrogen orthophosphate monohydrate (NaH PO ·H O) in 100 ml of water.

2 4 2
5 Apparatus
Use normal laboratory apparatus and the following.
Glassware shall be of grade A. Pipettes shall be calibrated.

Clean all glassware thoroughly. It is recommended that cleaning be done by boiling the glassware with

nitric acid (HNO ) of 30 % mass fraction, and then rinsing thoroughly with distilled water or water of

equivalent purity. Adequate cleanliness should be demonstrated through the analysis of method blanks.

5.1 Photoelectric absorptiometer (colorimeter), with a filter having a mean transmission of 520 nm.

The absorptiometer shall be used with an absorption cell having an optical path length of 10 mm.

5.2 Spectrophotometer, with wavelength set at 540 nm. The spectrophotometer shall be used with

an absorption cell having an optical path length of 10 mm.
© ISO 2021 – All rights reserved 3
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SIST EN ISO 3613:2021
ISO 3613:2021(E)
5.3 Analytical balance, with an accuracy of 0,10 mg.
6 Test methods
6.1 General

The test surface, prior to the following tests, shall be free of all contaminants, fingerprints and other

extraneous stains. If the surface is coated with a thin oil film, this shall be removed prior to the test

by degreasing using a suitable solvent at room temperature (not exceeding 35 °C). If it is necessary

to store samples, they shall be stored at temperatures not exceeding 40 °C and at a relative humidity

below 70 %. For test purposes, the samples shall not be subjected to forced drying at temperatures in

excess of 35 °C. Treatment in alkaline solutions shall not be performed as chromate conversion coatings

are broken down by alkalis. Spot tests are not always a precise means of determining the presence of

chromate coatings.
The test methods for the following are given in 6.2 to 6.7:

a) the presence of a colourless chromate coating on zinc, cadmium and aluminium-zinc alloys;

b) the presence of hexavalent chromium in both coloured and colourless chromate coatings;

c) the determination of hexavalent chromium content;
d) the determination of total chromium content.
The test methods for the following are given in 6.8, 6.9 and 6.10, respectively:
e) the determination of mass per unit area of chromate conversion coatings;
f) adhesion by abrasion;
g) the evaluation of the quality of chromate layer.
The tests shall be carried out within the following time limits:

— a minimum of 24 h after the application of the chromate conversion coating for almost all tests (6.2

to 6.4, 6.5.2 and 6.6 to 6.10);

— a minimum of 5 d after the application of the chromate conversion coating for the test specified in

6.5.3 to 6.5.5;
— a maximum of 3 d for the tests specified in 6.2 to 6.4 and 6.5.2;

— a maximum of 30 d for the tests specified in 6.6 and 6.7. It could be recommendable to apply this

limit also to the test specified in 6.5.3 to 6.5.5.
6.2 Test for the presence of a colourless chromate coating on zinc

Apply one drop of test solution A (4.1) to the chromated zinc surface. The formation of a red or red-

violet colour in the drop shall be deemed to indicate the presence of a chromate film.

6.3 Test for the presence of a colourless chromate coating on zinc and cadmium
Place one drop of test solution B (4.2) on the surface to be tested.

In the case of a zinc substrate, observe the appearance of the spot for 3 min. The formation of a dark

or black stain, at least 1 min after the application of the test solution, shall be deemed to indicate the

presence of a colourless chromate conversion coating.

Black stain formation after more than 3 min can be indicative of the presence of supplementary

coatings, such as wax or oil.
4 © ISO 2021 – All rights reserved
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SIST EN ISO 3613:2021
ISO 3613:2021(E)

In the case of a cadmium substrate, observe the appearance of the spot for 1 min. The formation of a

dark or black stain at least 5 s after the application of the test solution shall be deemed to indicate the

presence of a colourless chromate conversion coating.

Black stain formation after more than 1 min can be indicative of the presence of supplementary

coatings, such as wax or oil.

For comparison purposes, test an untreated surface similarly. Untreated zinc and cadmium surfaces, or

the surfaces that have been treated for the chromate conversion coating but do not have a continuous

coating, will react with the lead acetate solution to form a black stain on the untreated or bare zinc and

cadmium surfaces almost immediately, within 2 s to 5 s, after the application of the test solution.

No significance is to be placed upon any differences in the reaction time to black-spot formation between

1 min and 3 min on a zinc substrate, or between 5 s and 60 s on a cadmium substrate, with a colourless

chromate conversion treatment. Factors such as substrate surface texture (rou
...

SLOVENSKI STANDARD
oSIST prEN ISO 3613:2020
01-september-2020
Kovinske in druge anorganske prevleke - S kromanjem nanesene plasti na cinku,
kadmiju, zlitinah aluminij-cink in cink-aluminij - Metode preskušanja (ISO/DIS
3613:2020)

Metallic and other inorganic coatings - Chromate conversion coatings on zinc, cadmium,

aluminium-zinc alloys and zinc-aluminium alloys - Test methods (ISO/DIS 3613:2020)

Metallische und andere anorganische Überzüge - Chromatierüberzüge auf Zink,
Cadmium, Aluminium-Zink- und Zink-Aluminium-Legierungen - Prüfverfahren (ISO/DIS
3613:2020)

Revêtements métalliques et autres revêtements inorganiques - Couches de conversion

au chromate sur zinc, cadmium et alliages d'aluminium-zinc et de zinc-aluminium -

Méthodes d'essai (ISO/DIS 3613:2020)
Ta slovenski standard je istoveten z: prEN ISO 3613
ICS:
25.220.20 Površinska obdelava Surface treatment
oSIST prEN ISO 3613:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 3613:2020
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oSIST prEN ISO 3613:2020
DRAFT INTERNATIONAL STANDARD
ISO/DIS 3613
ISO/TC 107 Secretariat: KATS
Voting begins on: Voting terminates on:
2020-06-22 2020-09-14
Metallic and other inorganic coatings — Chromate
conversion coatings on zinc, cadmium, aluminium-zinc
alloys and zinc-aluminium alloys — Test methods

Revêtements métalliques et autres revêtements inorganiques — Couches de conversion au chromate sur

zinc, cadmium et alliages d'aluminium-zinc et de zinc-aluminium — Méthodes d'essai

ICS: 25.220.20
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PROVIDE SUPPORTING DOCUMENTATION. ISO 2020
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oSIST prEN ISO 3613:2020
ISO/DIS 3613:2020(E)
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© ISO 2020

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ii © ISO 2020 – All rights reserved
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oSIST prEN ISO 3613:2020
ISO/DIS 3613:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Reagents ........................................................................................................................................................................................................................ 2

5 Apparatus ..................................................................................................................................................................................................................... 3

6 Test methods ............................................................................................................................................................................................................. 4

6.1 General ........................................................................................................................................................................................................... 4

6.2 Test for the presence of a colourless chromate coating on zinc ................................................................... 4

6.3 Test for the presence of a colourless chromate coating on zinc and cadmium ............................... 4

6.4 Test for the presence of a colourless chromate coating on and zinc-aluminium

(mass fraction of aluminium: 5 %) alloys ........................................................................................................................ 5

6.5 Test for the presence of hexavalent chromium in both colourless and coloured

chromate coatings ................................................................................................................................................................................ 5

6.5.1 Test method employing test solution C 1 ................................................................................................... 5

6.5.2 Test method employing alternative test solution C 2 (destructive) .................................... 5

6.5.3 Expression of results .................................................................................................................................................... 6

6.5.4 Calibration of spectrophotometer .................................................................................................................... 7

6.6 Determination of hexavalent chromium content of coloured chromate coatings ........................ 7

6.6.1 Preparation of calibration graph ........................................................................................................................ 7

6.6.2 Blank test ................................................................................................................................................................................ 7

6.6.3 Determination .................................................................................................................................................................... 8

6.6.4 Expression of results .................................................................................................................................................... 8

6.7 Determination of total chromium content of coloured chromate coatings ........................................ 8

6.7.1 Preparation of calibration graph ........................................................................................................................ 8

6.7.2 Blank test ................................................................................................................................................................................ 8

6.7.3 Determination .................................................................................................................................................................... 8

6.7.4 Expression of results .................................................................................................................................................... 9

6.8 Determination of mass per unit area of both colourless and coloured chromate

coatings by gravimetric method .............................................................................................................................................. 9

6.9 Test for adhesion by abrasion .................................................................................................................................................... 9

6.10 Quality evaluation test of chromate layers on zinc and cadmium surfaces ........................................ 9

7 Test report ................................................................................................................................................................................................................... 9

Bibliography .............................................................................................................................................................................................................................10

© ISO 2020 – All rights reserved iii
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oSIST prEN ISO 3613:2020
ISO/DIS 3613:2020(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coating.

This fourth edition cancels and replaces the third edition (ISO 3613:2010), which has been technically

revised.
The main changes compared to the previous edition are as follows:
— Table 1 was amended.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
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oSIST prEN ISO 3613:2020
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Introduction

This document specifies methods for the qualitative determination of the presence of chromate

conversion coatings as well as the total chromium content of chromate conversion coatings.

The application of very thin, colourless, practically invisible chromate conversion coatings is frequently

called “passivation”, while the application of thicker, coloured chromate conversion coatings is called

“chromating”. The term “passivation” is not correct, does not comply with the ISO 2080 designation and

is therefore deprecated.
© ISO 2020 – All rights reserved v
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oSIST prEN ISO 3613:2020
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oSIST prEN ISO 3613:2020
DRAFT INTERNATIONAL STANDARD ISO/DIS 3613:2020(E)
Metallic and other inorganic coatings — Chromate
conversion coatings on zinc, cadmium, aluminium-zinc
alloys and zinc-aluminium alloys — Test methods

WARNING — This International Standard calls for the use of substances and/or procedures

that may be injurious to health if adequate safety measures are not taken. This International

Standard does not address any health hazards, safety or environmental matters associated with

its use. It is the responsibility of the user of this International Standard to establish appropriate

health, safety and environmentally acceptable practices and take suitable actions for any

national and international regulations. Compliance with this International Standard does not in

itself confer immunity from legal obligations.
1 Scope
This document specifies methods for the determination of
— the presence of colourless chromate conversion coatings,

— the presence of hexavalent chromium in colourless and coloured coatings on zinc or cadmium or

aluminium-zinc (mass fraction of aluminium: 55 %, within a range of 54 % to 56 % mass fraction)

and zinc-aluminium (mass fraction of aluminium: 5 %) alloys,
— the total chromium content per unit area on zinc and cadmium,
— the mass per unit area of both colourless and coloured coatings,
— the satisfactory adhesion of chromate conversion coatings, and
— the quality of chromate coatings.
These methods are applicable

— to colourless and coloured chromate conversion coatings containing trivalent and hexavalent

chromium in varying proportions and produced by either chemical or electrochemical processes, and

— only to chromate coatings that are free from any supplementary coatings, such as oil, water or

solvent-based polymers or wax.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 3892, Conversion coatings on metallic materials — Determination of coating mass per unit area —

Gravimetric methods

ISO 4520, Chromate conversion coatings on electroplated zinc and cadmium coatings

IEC 60068-2-30, Environmental testing — Part 2-30: Tests — Test Db: Damp heat, cyclic (12 h + 12 h cycle)

3 Terms and definitions
No terms and definitions are listed in this document.
© ISO 2020 – All rights reserved 1
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oSIST prEN ISO 3613:2020
ISO/DIS 3613:2020(E)

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Reagents

Use only reagents of recognized analytical grade and distilled water or water of equivalent purity,

unless otherwise specified, for analysis.
4.1 Test solution A (see 6.2).

Dissolve 1 g of diphenylcarbazide in a mixture of 20 ml of acetone, 60 ml of glacial acetic acid and 40 ml

of distilled water contained in a beaker. Add 15 ml of concentrated hydrochloric acid (ρ = 1,18 g/cm ),

stir and add slowly 30 ml of sodium hypochlorite solution (10 % to 15 % available chlorine). Add 5 ml

of hydrogen peroxide (30 % volume fraction) slowly with continuous stirring. Leave the solution in the

open beaker for 24 h in a fume cupboard, to allow excess chlorine to escape, before use.

The solution does not deteriorate with age and can be kept in a bottle with a loosely fitted stopper.

However, there may be losses due to evaporation and the concentration may alter so it is discarded

after 6 months.
4.2 Test solution B (see 6.3).

Dissolve 50 g of lead acetate trihydrate [(CH COO) Pb⋅3H O] in 1 l of distilled water or water of

3 2 2

equivalent purity. Ensure that the pH of the solution is between 5,5 and 6,8 as prepared. If the pH of the

solution is outside this range, discard the solution and obtain a new supply of lead acetate.

Any white precipitate formed during the initial preparation of the solution may be dissolved by small

additions of glacial acetic acid, provided that the pH is not reduced to a value below 5,5. Discard the

stock solution if the white precipitate does not disappear.
4.3 Test solution C (see 6.5)
4.3.1 Test solution C 1

Dissolve 0,4 g of diphenylcarbazide in a mixture of 20 ml of acetone and 20 ml of ethanol (96 %). After

dissolution, add 20 ml of 75 % orthophosphoric acid solution and 20 ml of distilled water. Prepare this

solution not more than 8 h prior to use.
4.3.2 Test solution C 2

Add 700 ml of orthophosphoric acid, of specific gravity 1,7, to 250 ml of distilled water or water of

equivalent purity and make up to 1 000 ml.

Dissolve 0,5 g of 1,5-diphenylcarbazide of analytical reagent grade in 50 ml of acetone of analytical

reagent grade. Dilute slowly, while stirring, with 50 ml of distilled water or water of equivalent purity

(rapid mixing may result in precipitation of dipehnylcarbazide). Keep the solution in a dark glass bottle

in the refrigerator. The solution shall be discarded after 4 weeks or earlier when the solution becomes

discoloured.

For the Cr(VI) stock solution, dissolve 0,113 g of K Cr O of analytical reagent grade (dried for 1 h at

2 2 7

100 °C before use) in distilled water or water of equivalent purity and make up to the mark in a 1 000 ml

volumetric flask. The solution shall be discarded after 9 months.
From this stock solution prepare two Cr(VI) standard solutions.
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For 0,10 µg/ml Cr(VI): Measure 2,5 ml of this solution into a second 1 000 ml volumetric flask and make

up to the mark. 1 ml of this standard solution contains 0,1 µg of Cr(VI).

For 0,13 µg/ml Cr(VI): Measure 3,3 ml of this solution into a third 1 000 ml volumetric flask and make

up to the mark. 1 ml of this standard solution contains 0,13 µg of Cr(VI).

For the preparation of the comparison solution for 0,10 µg/cm Cr(VI), add 1 ml of orthophosphoric

acid and 1 ml of diphenylcarbazide solution to 50 ml of the standard Cr(VI) solution solution with 0,10

µg/ml Cr(VI) and mix thoroughly. Then add 2 ml of the diphenylcarbazide solution and mix .Allow the

solution to stand for 10 min for the colour reaction to be completed.

For the preparation of the comparison solution for 0,13 µg/cm Cr(VI), add 1 ml of orthophosphoric

acid to 50 ml of the standard Cr(VI) solution with 0,13 µg/ml Cr(VI) and mix thoroughly. Then add 2 ml

of the diphenylcarbazide solution and mix. Allow the solution to stand for 10 min for the colour reaction

to be completed.
4.4 Test solution D (see 6.6 and 6.7).

Dissolve 0,50 g of diphenylcarbazide in 50 ml of acetone. Dilute slowly, while stirring, with 50 ml of

water (rapid mixing can result in precipitation of diphenylcarbazide).

For maximum stability, store the solution under refrigeration in an amber-coloured glass bottle.

4.5 Sulfuric acid, diluted 1 + 3.

Slowly add 1 volume of concentrated sulfuric acid (ρ = 1,84 g/cm ) to 3 volumes of water.

4.6 Ammonium persulfate [(NH ) S O ].
4 2 2 8
4.7 Sodium hydroxide (NaOH), 240 g/l solution.
4.8 Silver nitrate (AgNO ), 17 g/l solution.
4.9 Potassium dichromate (K Cr O ), standard solution.
2 2 7

Dilute 2 ml of standard volumetric potassium dichromate solution (4,9 g/l) to 1 000 ml.

4.10 Phosphate buffer solution.

Dissolve 55 g of sodium dihydrogen orthophosphate monohydrate (NaH PO ⋅H O) in 100 ml of water.

2 4 2
5 Apparatus
Use normal laboratory apparatus and the following.
Glassware shall be of grade A. Pipettes shall be calibrated.

Clean all glassware thoroughly. It is recommended that cleaning be done by boiling the glassware with

nitric acid (HNO ) of 30 % mass fraction and then rinsing thoroughly with distilled water or water of

equivalent purity. Adequate cleanliness should be demonstrated throug
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