SIST EN ISO 17668:2016

SLOVENSKI STANDARD
SIST EN ISO 17668:2016
01-maj-2016
1DGRPHãþD
SIST EN 13811:2003
Cinkove difuzijske prevleke na železovih izdelkih - Šeradiranje - Specifikacija (ISO
17668:2016)
Zinc diffusion coatings on ferrous products - Sherardizing - Specification (ISO
17668:2016)
Zink-Diffusionsbeschichtungen auf Eisen - Sherardisieren - Anforderungen (ISO
17668:2016)
Revêtements par diffusion de zinc sur les produits ferreux - Shérardisation - Spécification
(ISO 17668:2016)
Ta slovenski standard je istoveten z: EN ISO 17668:2016
ICS:
25.220.40 Kovinske prevleke Metallic coatings
77.120.60 Svinec, cink, kositer in Lead, zinc, tin and their
njihove zlitine alloys
SIST EN ISO 17668:2016 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 17668:2016

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SIST EN ISO 17668:2016


EN ISO 17668
EUROPEAN STANDARD

NORME EUROPÉENNE

March 2016
EUROPÄISCHE NORM
ICS 25.220.40 Supersedes EN 13811:2003
English Version

Zinc diffusion coatings on ferrous products - Sherardizing -
Specification (ISO 17668:2016)
Revêtements par diffusion de zinc sur les produits Zink-Diffusionsüberzüge auf Eisen - Sherardisieren -
ferreux - Shérardisation - Spécification (ISO Anforderungen (ISO 17668:2016)
17668:2016)
This European Standard was approved by CEN on 2 January 2016.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, 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: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 17668:2016 E
worldwide for CEN national Members.

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SIST EN ISO 17668:2016
EN ISO 17668:2016 (E)
Contents Page
European foreword . 3
2

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SIST EN ISO 17668:2016
EN ISO 17668:2016 (E)
European foreword
This document (EN ISO 17668:2016) 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” 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 September 2016, and conflicting national standards
shall be withdrawn at the latest by September 2016.
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 any or all such patent
rights.
This document supersedes EN 13811:2003.
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, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 17668:2016 has been approved by CEN as EN ISO 17668:2016 without any modification.


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SIST EN ISO 17668:2016

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SIST EN ISO 17668:2016
INTERNATIONAL ISO
STANDARD 17668
First edition
2016-02-01
Zinc diffusion coatings on ferrous
products — Sherardizing —
Specification
Revêtements par diffusion de zinc sur les produits ferreux —
Shérardisation — Spécification
Reference number
ISO 17668:2016(E)
©
ISO 2016

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SIST EN ISO 17668:2016
ISO 17668:2016(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved

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SIST EN ISO 17668:2016
ISO 17668:2016(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General requirements . 3
4.1 Surface condition base material . 3
4.2 Information to be supplied by the purchaser . 3
5 Acceptance inspection and sampling . 3
6 Coating properties . 4
6.1 Appearance . 4
6.2 Thickness . 4
6.2.1 General. 4
6.2.2 Test methods . 4
6.2.3 Reference areas . 5
6.2.4 Magnetic method or electro-magnetic method . 5
6.2.5 Gravimetric method . 5
6.2.6 Thickness requirements . 5
6.3 Acceptance criteria . 6
6.4 Additional clearances for threaded components . 6
7 Ceritificate of compliance . 6
Annex A (normative) Information to be supplied by the purchaser to the sherardizer .7
Annex B (informative) Determination of thickness . 8
Annex C (informative) General information .10
Annex D (informative) Corrosion resistance of sherardized layers .12
Bibliography .13
© ISO 2016 – All rights reserved iii

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SIST EN ISO 17668:2016
ISO 17668:2016(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 on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information.
The committee responsible for this document is ISO/TC 107, Metallic and other inorganic coatings,
Subcommittee SC 4, Hot dip coatings (galvanized, etc.).
iv © ISO 2016 – All rights reserved

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SIST EN ISO 17668:2016
ISO 17668:2016(E)

Introduction
Sherardizing is a thermal diffusion coating process in which ferrous articles are heated in the presence
of a sherardizing mixture consisting of zinc dust with or without an inert material.
The process is commonly performed in closed, slowly rotating or fixed containers at temperatures
ranging from around 300 °C to 500 °C. The normal processing temperature is below the melting point
of zinc (419 °C).
During the process, zinc reacts with the surface to form inter-metallic layers on ferrous articles.
A coating thickness of 10 µm to 75 µm (and higher if required) can be achieved. The coating thickness is
accurately controlled by the amount of zinc dust, processing time and temperature. The coating closely
follows the contours of the base material and uniform coating thicknesses are produced on articles,
including those of irregular shape.
After sherardizing, the container load is cooled down. A screening process separates the sherardized
articles from the unused sherardizing mixture. The articles, with the zinc-iron inter-metallic layers, are
eventually post-treated (by phosphating, chromating or another suitable passivation process) resulting
in a clean and passivated surface.
It is common to use articles coated with zinc-iron inter-metallic layers as a primer or base-coat for
duplex-systems.
For additional information about the sherardizing process and the application possibilities of
sherardized articles, see Reference [12] and Reference [13].
Sherardizing (thermal diffusion coating) is also known as the following:
— diffusion zinc plating (Germany);
— thermal diffusion coating (Russia);
— thermal diffusion galvanizing (Ukraine);
— vapour galvanizing (UK);
— zinc diffusion coating (USA);
— zinc inter-metallic coating (Russia);
— zinc thermo diffusion galvanizing (Israel).
In China, Europe and the USA, the common name for the thermal diffusion coating process is
sherardizing.
© ISO 2016 – All rights reserved v

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SIST EN ISO 17668:2016

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SIST EN ISO 17668:2016
INTERNATIONAL STANDARD ISO 17668:2016(E)
Zinc diffusion coatings on ferrous products — Sherardizing
— Specification
1 Scope
This International Standard specifies minimum thickness requirements for six classes of zinc diffusion
layers applied to ferrous products by the sherardizing process for the purpose of protection against
corrosion and wear.
This International Standard does not specify any requirements for the surface condition (finish or
roughness) of the basis material before sherardizing.
Post-treatments (conversion coatings), after-treatments or organic over-coatings (Duplex) of
sherardized articles are not in the scope of this International Standard.
NOTE 1 For general information about post-treatments, see Annex C and Annex D.
This International Standard does not apply to sherardized products (e.g. fasteners, tubes) for which
specific standards exist and which might include additional requirements or requirements which are
different from those of this International Standard.
NOTE 2 Individual product standards can incorporate this International Standard for the coating by quoting
its number, or can incorporate it with modification specific to the product.
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.
ISO 1460, Metallic coatings — Hot dip galvanized coatings on ferrous materials — Gravimetric
determination of the mass per unit area
ISO 2064, Metallic and other inorganic coatings — Definitions and conventions concerning the
measurement of thickness
ISO 2178, Non-magnetic coatings on magnetic substrates — Measurement of coating thickness —
Magnetic method
ISO 2808, Paints and varnishes — Determination of film thickness
ISO 10474, Steel and steel products — Inspection documents
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 2064 and the following apply.
3.1
sherardizing process
zinc diffusion coating process in which articles are heated in close contact with a sherardizing mixture
(3.3), commonly performed in a closed slowly rotating container or a fixed (non-rotating) container, to
form sherardized layers (3.2)
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SIST EN ISO 17668:2016
ISO 17668:2016(E)

3.2
sherardized layer
zinc diffusion layer
zinc diffusion coating consisting of zinc-iron alloy layers obtained by sherardizing
Note 1 to entry: The “sherardized layer” is referred to in this International Standard as “coating”.
Note 2 to entry: The sherardized layer may subsequently be post-treated by phosphating, chromating or another
suitable passivation process (guidance for these post-treatments are given in Annex C and Annex D).
3.3
sherardizing mixture
mixture consisting of mainly zinc dust, with or without other process-supporting ingredients
Note 1 to entry: Zinc dust is also known as zinc powder.
3.4
mass of the zinc diffusion layer
total mass of zinc/iron alloys per unit area of surface
2
Note 1 to entry: The mass of the zinc diffusion layer is expressed in grams per square metre (g/m ).
3.5
thickness of the zinc diffusion layer
total zinc diffusion layer thickness consisting of zinc/iron alloys
Note 1 to entry: The thickness of the zinc diffusion layer is expressed in micrometre (µm).
3.6
significant surface
part of the article covered or to be covered by the zinc diffusion layer (3.2) and for which these coating is
essential for serviceability and/or appearance and where the layer will meet all the specified requirements
3.7
control sample
article, or group of articles, from a lot which is selected for testing
3.8
reference area
area within which a specified number of single measurements is required to be made
3.9
local thickness of the zinc diffusion layer
mean value of zinc diffusion layer thickness obtained from the specific number of measurements within
a reference area (3.8) for a magnetic or electro-magnetic test or the single value of a gravimetric test
Note 1 to entry: Guidance for the methods of measurement of the zinc diffusion layer thickness is given in
6.2.2 and Annex B.
3.10
mean thickness of the zinc diffusion layer
average value of the local zinc diffusion layer thicknesses of different reference areas (3.8)
Note 1 to entry: In case there is only one reference area (3.8), the mean zinc diffusion layer thickness is the same
as the local zinc diffusion layer thickness.
3.11
inspection lot
one or more articles of the same type and size comprising either a single order, a single delivery load or
the number of articles identified as a lot by the sherardizer
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SIST EN ISO 17668:2016
ISO 17668:2016(E)

3.12
acceptance inspection
inspection of an inspection lot (3.11) at the sherardizer’s works (unless otherwise specified)
4 General requirements
4.1 Surface condition base material
The surface of the base material should be clean before sherardizing.
Surface contamination that cannot be removed by grit blasting should be removed prior to the
mechanical pre-treatment process. The responsibility of removing the contamination should be agreed
upon between the sherardizer and purchaser.
The surface condition of the base material, the mass of the parts and the sherardizing conditions can
affect the appearance, the thickness, surface roughness and the physical and mechanical properties of
the coating. This International Standard does not define any requirements regarding these properties.
NOTE Guidance on these parameters can be found in ISO 14713-3:2009, Clause 4.
4.2 Information to be supplied by the purchaser
Information shall be supplied by the purchaser in accordance with A.1 and A.2.
5 Acceptance inspection and sampling
Acceptance inspection shall be undertaken before the products leave the sherardizer’s custody, unless
otherwise specified at the time of ordering by the purchaser.
Acceptance inspection involves the assessment of appearance of the coated article and testing the
thickness. The results of other tests of the coated article are normally not provided. Other tests will
only be carried out by agreement between purchaser and sherardizer made at the time of ordering.
A control sample for thickness testing shall be taken randomly from each inspection lot selected for
testing. The minimum number of articles to form the control sample shall be taken in accordance
with Table 1.
Alternatively, sampling procedures selected from ISO 2859-1, ISO 2859-2, and ISO 2859-3 can be used.
Table 1 — Control sample size related to batch size
Number of articles in the Minimum number of
batch articles in the control
sample
1 to 3 All
4 to 500 3
501 to 1 200 5
1 201 to 3 200 8
3 201 to 10 000 13
Above 10 000 20
...