EN ISO 9717:2013

SLOVENSKI STANDARD
01-april-2014
1DGRPHãþD
SIST EN 12476:2000
Kovinske in druge anorganske prevleke - Fosfatne prevleke na kovinah (ISO
9717:2010)
Metallic and other inorganic coatings - Phosphate conversion coating of metals (ISO
9717:2010)
Metallische und andere anorganische Überzüge - Phosphatüberzüge auf Metallen (ISO
9717:2010)
Revêtements métalliques et autres revêtements inorganiques - Couches de conversion
au phosphate sur métaux (ISO 9717:2010)
Ta slovenski standard je istoveten z: EN ISO 9717:2013
ICS:
25.220.40 Kovinske prevleke Metallic coatings
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 9717
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2013
ICS 25.220.20 Supersedes EN 12476:2000
English Version
Metallic and other inorganic coatings - Phosphate conversion
coating of metals (ISO 9717:2010)
Revêtements métalliques et autres revêtements Metallische und andere anorganische Überzüge -
inorganiques - Couches de conversion au phosphate sur Phosphatüberzüge auf Metallen (ISO 9717:2010)
métaux (ISO 9717:2010)
This European Standard was approved by CEN on 28 March 2013.

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

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 9717:2013: E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
The text of ISO 9717:2010 has been prepared by Technical Committee ISO/TC 107 “Metallic and other
inorganic coatings” of the International Organization for Standardization (ISO) and has been taken over as EN
ISO 9717:2013 by 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 October 2013, and conflicting national standards shall be withdrawn at
the latest by October 2013.
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 12476:2000.
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 9717:2010 has been approved by CEN as EN ISO 9717:2013 without any modification.

INTERNATIONAL ISO
STANDARD 9717
Second edition
2010-12-15
Metallic and other inorganic coatings —
Phosphate conversion coating of metals
Revêtements métalliques et autres revêtements inorganiques —
Couches de conversion au phosphate sur métaux

Reference number
ISO 9717:2010(E)
©
ISO 2010
ISO 9717:2010(E)
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ii © ISO 2010 – All rights reserved

ISO 9717:2010(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .2
4 Information to be supplied by the purchaser to the processor.3
4.1 Essential information.3
4.2 Additional information .3
5 Designation .3
5.1 General .3
5.2 Designation specifications.4
5.3 Designation of heat treatment requirements.4
5.4 Classification of phosphate conversion coating .5
6 Requirements.6
6.1 Surface preparation.6
6.2 Phosphate conversion coating .6
6.3 Processing after phosphating.6
6.4 Thickness of coating.7
6.5 Stress-relief heat treatment before cleaning and phosphating.8
6.6 Hydrogen-embrittlement-relief heat treatment after phosphating .8
6.7 Treatments for supplementary coatings.8
6.8 Adhesion of phosphate conversion coatings .9
6.9 Quality-evaluation test of phosphate conversion coatings.9
7 Sampling .9
Annex A (informative) Methods of application, characteristics and significance of phosphate
conversion coatings.10
Annex B (informative) Determination of rinse-water contamination .13
Annex C (informative) Identification of phosphate conversion coating .15
Annex D (normative) Salt droplet test .17
Annex E (normative) Determination of resistance of phosphate conversion coating to neutral salt
spray (fog) test.20
Annex F (normative) Treatments for supplementary coating .22
Bibliography.23

ISO 9717:2010(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 9717 was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coatings,
Subcommittee SC 8, Chemical conversion coatings.
This second edition cancels and replaces the first edition (ISO 9717:1990), which has been technically revised.
iv © ISO 2010 – All rights reserved

ISO 9717:2010(E)
Introduction
Phosphate conversion coatings are applied to ferrous metals, aluminium, zinc and their alloys (including
zinc- and zinc-alloy-plated steel, cadmium and their alloys) either as an end finish or as an intermediate layer
for other coatings. They are intended to
a) impart corrosion resistance,
b) improve adhesion to paints and other organic finishes,
c) facilitate cold-forming operations, such as wire drawing, tube drawing and extrusion, and
d) modify surface frictional properties so as to facilitate sliding.
Phosphate conversion coatings are produced by treatment with solutions, the main constituents of which are
the appropriate dihydrogen orthophosphates. These coatings are applied principally to ferrous materials,
aluminium, zinc and cadmium and differ in coating mass per unit area and apparent density, depending on
a) the construction material and surface condition of the components,
b) previous mechanical and chemical treatment of the components, and
c) processing conditions for phosphating.
All phosphate conversion coatings are more or less porous but can be sealed substantially by subsequent
sealing processes.
INTERNATIONAL STANDARD ISO 9717:2010(E)

Metallic and other inorganic coatings — Phosphate conversion
coating of metals
WARNING — This International Standard may not be compliant with some countries' health, safety
and environmental legislations and 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 and legislations associated with its use.
It is the responsibility of the producers, purchasers and/or user of this International Standard to
establish appropriate health, safety and environmentally acceptable practices and take appropriate
actions to comply with any national, regional and/or international rules and regulations. Compliance
with this International Standard does not in itself confer immunity from legal obligations.
1 Scope
This International Standard specifies requirements for the processing of ferrous metals, aluminium, zinc,
cadmium and their alloys to produce coatings consisting essentially of inorganic phosphates, which are
intended to be used in conjunction with supplementary treatments for the protection of the basis metal against
corrosion and to provide anti-wear properties to sliding surfaces, adhesion to organic finishes and ease of
cold-forming operations.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 1463, Metallic and oxide coatings — Measurement of coating thickness — Microscopical method
ISO 2064, Metallic and other inorganic coatings — Definitions and conventions concerning the measurement
of thickness
ISO 2080, Metallic and other inorganic coatings — Surface treatment, metallic and other inorganic coatings —
Vocabulary
ISO 2819, Metallic coatings on metallic substrates — Electrodeposited and chemically deposited coatings —
Review of methods available for testing adhesion
ISO 2859 (all parts), Sampling procedures for inspection by attributes
ISO 3892, Conversion coatings on metallic materials — Determination of coating mass per unit area —
Gravimetric methods
ISO 4519, Electrodeposited metallic coatings and related finishes — Sampling procedures for inspection by
attributes
ISO 9587, Metallic and other inorganic coatings — Pretreatment of iron or steel to reduce the risk of hydrogen
embrittlement
ISO 9717:2010(E)
ISO 9588, Metallic and other inorganic coatings — Post-coating treatments of iron or steel to reduce the risk
of hydrogen embrittlement
ISO 15724, Metallic and other inorganic coatings — Electrochemical measurement of diffusible hydrogen in
steels — Barnacle electrode method
ISO 27831-1, Metallic and other inorganic coatings — Cleaning and preparation of metal surfaces — Part 1:
Ferrous metals and alloys
ISO 27831-2, Metallic and other inorganic coatings — Cleaning and preparation of metal surfaces — Part 2:
Non-ferrous metals and alloys
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1463, ISO 2064, ISO 2080,
ISO 2819, ISO 9587 and ISO 9588 and the following apply.
3.1
free acid of a phosphating solution
number of millilitres of 0,4 % mass fraction of sodium hydroxide solution required to neutralize 10 ml of the
phosphating solution to pH 4, using methyl orange or an equivalent indicator system
3.2
pointage
measure of the total acidity of a phosphating solution, i.e. the number of millilitres of 0,4 % mass fraction of
sodium hydroxide solution required to neutralize 10 ml of the phosphating solution to pH 10 using
phenolphthalein as an indicator
3.3
accelerated process
process where the processing solution is of the metal phosphate/phosphoric acid type containing additions
such as oxidizing agents, e.g. nitroguanidine, nitrate, nitrite, or chlorate, which accelerate the coating
formation
3.4
unaccelerated process
process where the processing solution is of the plain metal phosphate/phosphoric acid type and no
accelerating agents are employed
3.5
sealing
application of a supplementary coating to the phosphate surface immediately after phosphating, rinsing and
drying, to form a complete protective or lubrication system
3.6
supplementary coating
covering material, usually of an organic nature
EXAMPLES oil, grease, lacquer, varnish, paint or dry lubricant
2 © ISO 2010 – All rights reserved

ISO 9717:2010(E)
4 Information to be supplied by the purchaser to the processor
4.1 Essential information
When ordering articles to be phosphated in accordance with this International Standard, the purchaser shall
provide the following information in writing, in, for example, the contract or purchase order, or on engineering
drawings:
a) a reference to this International Standard, ISO 9717:2010, and the designation (see Clause 5);
b) the nominal composition, specification, nature and metallurgical condition of the basis metal, if they are
likely to affect the serviceability and/or the appearance of the coating;
c) the significant surfaces, to be indicated on drawings of the parts or by providing suitably marked
specimens;
d) the coating classification code (see 5.4);
e) the coating mass per unit area, or the coating thickness with any tolerance limit required, and the relevant
test method (see 6.4);
f) tensile strength of parts and the requirements of heat treatment before and/or after the phosphating
process (see 6.5 and 6.6);
g) the surface preparation required prior to phosphate conversion coating (see 6.1);
h) the surface appearance (see 6.1);
i) the requirements for, and type of, supplementary treatments, e.g. staining, oil, grease, organic coatings,
etc. (see 6.7);
j) the requirement for a quality-evaluation test for controlling the quality and continuity of the coating, test
method to be used and minimum exposure time (see 6.9);
k) the sampling methods, acceptance levels and/or any other inspection requirements (see Clause 7).
4.2 Additional information
The following additional information shall also be provided by the purchaser, when appropriate:
a) for creviced items, the phosphate process and/or nature of accelerator employed;
b) for high-strength steels, details of any special process requirements;
c) the properties of the coating, such as surface profile and crystal size;
d) any other requirements, such as cascaded process in rinsing or whether removal of supplementary
coatings is needed prior to examination of corroded test specimens (see 6.3.1, 6.8, 6.9 and Annex F).
5 Designation
5.1 General
The designation shall appear on engineering drawings, in the purchase order, in the contract or in the detailed
product specification.
ISO 9717:2010(E)
The designation specifies, in the following order, the basis metal, the specific alloy (optional), stress-relief
requirements, the thickness (or mass) and composition of the phosphate coating, heat treatment to reduce
susceptibility to hydrogen embrittlement, and treatments for, including the type of, supplementary coating.
5.2 Designation specifications
The coating designation specifies the basis metal and the types and thickness of coatings appropriate for
each service condition number and comprises the following:
a) the term, “Phosphate conversion coating”, the number of this International Standard, ISO 9717, followed
by a hyphen;
b) the chemical symbol for the basis metal (or for the principal metal if an alloy) followed by a solidus (/) as
follows:
⎯ Fe for iron or steel;
⎯ Zn for zinc or zinc alloys;
⎯ Al for aluminium or aluminium alloys;
⎯ Cd for cadmium;
c) the designation SR (see 5.3), if necessary, followed by a solidus;
d) a symbol describing the type of coating;
e) a number indicating the coating mass per unit area, in grams per square metre, followed by a solidus;
f) a symbol indicating additional treatments for supplementary coating of the phosphate layer followed by a
solidus (see Table E.1);
g) the designation ER (see 5.3), if necessary, followed by a solidus;
h) a symbol indicating any additional treatments for supplementary coating of the phosphate layer.
Solidi (/) shall be used to separate data fields in the designation corresponding to the different sequential
processing steps. Double separators or solidi indicate that a step in the process either is not required or has
been omitted.
If supplementary treatments other than, or in addition to, sealing are used, the designation shall be
Fe/ZnMeph25/X/Y, where ZnMeph represents appropriate metal phosphate if zinc remains as the main metal
constituent of the coating or phosphate of a double salt with, for example, 25 g/m coating mass per unit area,
and X and Y represent the supplementary coating codes given in Table F.1.
It is recommended that the specific alloy be identified by its standard designation following the chemical
symbol of the basis metal; for example, its UNS number, or the national or regional equivalent, may be placed
between the symbols < >. For example, Fe is the UNS designation for one high-strength steel. (See
Reference [6] in the Bibliography).
5.3 Designation of heat treatment requirements
The heat treatment requirements shall be in brackets and designated as follows:
a) the letters SR, for stress-relief heat treatment prior to electroplating, and/or the letters ER, for hydrogen-
embrittlement-relief heat treatment after electroplating;
b) in parenthesis, the minimum temperature, in degrees Celsius;
4 © ISO 2010 – All rights reserved

ISO 9717:2010(E)
c) the duration of the heat treatment, in hours.
For example, [SR(210)1] designates, without square brackets, stress-relief heat treatment at 210 °C for 1 h.
EXAMPLE 1 Designation of a zinc-phosphate-type coating (Class II) on iron or steel at a mass per unit area of 5 g/m
with after-treatments of inorganic sealants (T2) and organic coating or varnishes (T1):
Phosphate conversion coating ISO 9717 – Fe/Znph5/T2/T1
EXAMPLE 2 Designation of a zinc phosphate coating of 5 g/m on iron or steel (Fe) which is stress relieved at 200 °C
for 3 h prior to phosphate coating, is heat-treated after phosphate coating for hydrogen-embrittlement relief for 8 h at
190 °C [ER(190)8] and has been given an inorganic sealant (T2) and a treatment for supplementary coating, such as an
organic coating (T1):
Phosphate conversion coating ISO 9717 – Fe/SR(200)3/Znph5/ER(190)8/T2/T1
5.4 Classification of phosphate conversion coating
The classification of phosphate coatings for steel parts is used by the purchaser to specify the degree of
protection required or where parts are deformed during further fabrication after application of supplementary
coatings:
I) Maximum corrosion protection (not less than 7,5 g/m )
A coating consisting essentially of inorganic phosphates of manganese or iron and having a mass of not less
than 7,5 g/m of treated surface. The coating is produced by certain immersion-type accelerated or
unaccelerated processes. This class is used normally when sealing with oil or grease supplementary
treatments is specified, and maximum corrosion protection (or wear resistance) is desired. It is not
recommended for use under organic coatings, varnish, and lacquer finishes on sheet materials less than
1 mm thick.
II) General protective purpose (not less than 4,5 g/m )
A coating consisting essentially of inorganic phosphates of zinc and having a mass of not less than 4,5 g/m
of treated surface. The coating is usually produced by an immersion-type accelerated process. This class will
normally be used for general protective purposes under organic coating systems. A Class I coating may be
used when a Class II coating is called for, except on thin sheet materials.
2 2
III) Pretreatment of thin sheet-steel sections (1,5 g/m to 4,5 g/m )
A coating consisting essentially of inorganic phosphates of zinc or iron and having a mass within the range
2 2
1,5 g/m to 4,5 g/m of treated surface. The coating is usually produced by a spray-type accelerated process.
This class will normally be used only for the pretreatment of thin sheet-steel sections under organic coatings,
varnish, or lacquer coatings of high protective value.
2 2
IV) For fabrication following organic or lacquer coatings (0,2 g/m to 1,5 g/m )
A coating consisting essentially of inorganic phosphates of zinc or iron having a mass within the range
2 2
0,2 g/m to 1,5 g/m of treated surface. This class is normally used where items are to be deformed during
further fabrication after the application of organic coatings, varnish, or lacquer.
Other coating types exist, including zinc phosphate modified with iron and/or nickel and/or manganese. The
modifying metal will normally be present in the form of a double salt such as Zn Me(P0 )⋅4H 0, where Me
2 4 2 2
represents Fe(ll), Ni or Mn., if zinc remains the main metal constituent of these coatings, which, to avoid
confusion, have not been given separate designations. Metal from the substrate material will often be
incorporated in the conversion coating.
ISO 9717:2010(E)
6 Requirements
6.1 Surface preparation
All items shall be prepared in accordance with ISO 27831-1 or ISO 27831-2, as appropriate, to produce a
chemically clean surface, unless otherwise specified by the purchaser. Items with folds, seams, or crevices
shall receive special attention to ensure removal of oil, grease, or other foreign matter. The method of removal
shall be chosen with due regard to its effect on the properties of the item and the formation of high-quality
phosphate coatings.
After alkali or acid cleaning, the items shall be rinsed thoroughly in cold or hot water to remove all residues of
cleaning materials that would otherwise affect the quality of the coating or the efficacy of the phosphating
solution. Where acid pickling has been employed, it may be necessary to follow the use of pickling solutions
containing wetting agents or inhibitors by dipping in an acid solution without a wetting agent or inhibitor, or by
dipping in a suitable alkaline solution in order to remove adsorbed films.
Both acid and strong alkali treatments can result in the formation of coarse crystalline phosphate coatings of
poor quality. Post-cleaning conditioning treatments to prevent such coarse coatings may be used. The post-
cleaning conditioning treatments are intended to remove all traces of residual acid or alkali solution, i.e. a mild
alkali solution to remove all traces of acid and a mild acid solution to remove all traces of alkali [see 4.1 g)].
A conditioning rinse is normally used immediately prior to phosphating, to favour the formation of fine grain
coatings without further rinsing. Materials based on titanium salts are also used and are widely available from
proprietary sources. It is also possible to incorporate such materials in mildly alkaline spray cleaners, thus
obviating the need for a separate conditioning rinse. However, in this case, rinsing before phosphating is
essential.
6.2 Phosphate conversion coating
Only processes capable of meeting the requirements of this International Standard shall be used.
Composite items made up of ferrous and non-ferrous (such as aluminium, magnesium, nickel) items shall
normally have their ferrous items phosphated before assembly. These can be zinc phosphated, provided that
the baths are appropriately modified for this type of applications. Exceptions can be allowed in cases of
composite items containing zinc-base material or copper-base material (the copper-base material should not
constitute more than about 10 % of the total surface) provided that the joint is unlikely to be penetrated by the
phosphating solution.
For high-strength steels of a tensile strength greater than or equal to 1 000 MPa, a normally accelerated,
copper-free process is used.
Normally, plants are constructed of steel and care should be taken to avoid the use of unsuitable materials in
plant construction, e.g. copper or brass heating coils, which will contaminate the phosphating solution and
adversely affect the quality of the phosphate coating.
The phosphate layer shall be uniform and matt in appearance, free from spots, uncoated areas, scratches,
powdery and white residues. Differences in colour or shade in different areas, or from piece to piece, are not
considered as causes for rejection.
Minor variations in the appearance of phosphate coatings caused, for example, by variations in the surface of
the basis material or by contact with racks during phosphating, are common and are not normally indicative of
important fluctuations in performance.
Methods of application and characteristics of phosphate conversion coatings are given in Annex A.
6.3 Processing after phosphating
Following phosphating, components are rinsed, stained, if specified, and dried as follows.
6 © ISO 2010 – All rights reserved

ISO 9717:2010(E)
6.3.1 Rinsing
After phosphating, thorough rinsing with water is necessary in order to remove soluble salts which would
otherwise tend to promote blistering under organic coatings. Parts, especially those with crevices, folds, or
seams, as well as those treated with the accelerated phosphating process, shall be rinsed as follows:
a) After treatment by an accelerated process, items are rinsed thoroughly, first in flowing cold water and
then in hot water at a minimum temperature of 75 °C, and finally washed in the hot dilute “chromic”
solution described below. The accumulation of treatment chemicals in the rinse waters is avoided by
maintaining a sufficient flow of cold water and by periodic renewal of hot water. The acidity of the hot
water shall not be allowed to exceed that corresponding to 0,75 ml of 0,4 % (mass fraction) sodium
hydroxide solution when tested by a suitably calibrated pH meter or by any other appropriate method.
Alternative processes to the chromic rinse such as those based on silane acid systems may be used provided
that the efficiency and appropriate control of the process can be confirmed.
b) After treatment by an unaccelerated process, items are rinsed in flowing cold water, then in either hot
water (65 °C minimum) or the hot dilute “chromic” solution (65 °C minimum).
The “chromic” wash solution normally consists of the range of 15 g to 50 g of chromic acid, or of alkali metal
chromate or alkali metal dichromate, or of a mixture containing approximately equal parts of chromic and
phosphoric acids, per 100 litres of water. A higher concentration than the maximum quoted above is not to be
used on surfaces which will be in contact with, or in proximity to, hazardous substances. In other cases, higher
concentrations of chromic acid, chromate or dichromate may be used up to a maximum of 500 g per 100 litres
of water, where such concentrations will give overall beneficial results and where the effect of local enrichment
or drainage will not be detrimental under organic-based systems.
WARNING — The repeated handling with bare hands of items that have been given a “chromic” wash
may constitute a health hazard.
c) The wash waters, hot or cold, used for unaccelerated and accelerated processes shall not contain
chloride, calculated as chloride ion, in excess of 0,5 g/l, when determined by the method described in
Annex B.
6.3.2 Staining
Parts that are to be stained by water soluble pigment are dyed at this stage [see 4.1 j)]. Staining by spirit dye
is dyed after drying.
6.3.3 Drying
Parts are dried after thorough rinsing. Forced drying is also used, especially for those with crevices, seams,
etc.
6.3.4 Identification of type of phosphate conversion coating
Details of the procedures of identification of types of phosphate conversion coatings are described in Annex C.
6.4 Thickness of coating
The coating mass, rather than thickness, is measured in accordance with ISO 3892 and shall be determined
on an item after treatment by phosphating, washing, and drying and before any heat treatment and sealing
(see 5.4).
For quality assurance purposes, instruments which are available and which give a direct reading of coating
mass per unit area may be used. It is, however, essential that they are calibrated against standard coatings
having a coating mass per unit area of the same order as those being inspected.
ISO 9717:2010(E)
In the case of heavy coatings, the amount of phosphate deposited is sometimes expressed in terms of coating
thickness, particularly for quality-control purposes. The use of this alternative (and selection of a relevant test
method) shall be agreed by the purchaser [see 4.1 e)].
If required, other properties of the coating, such as surface profile and crystal size, may also be specified
[see 4.2 d)].
If proprietary processes are used, dimensional changes resulting from phosphating treatments are normally
within a maximum increase of 8 µm/surface, depending on the particular process selected and a strict
adherence to the process manufacturer's operating instructions. Deviation from the specified operating
conditions of the phosphating solution can result in excessive attack of the item, with a possible decrease in
dimensions and uneven coatings of inferior properties.
The dimensions of the finished item shall be those of the item after phosphating and before the application of
any supplementary cover. Where phosphating is used to give anti-wear properties to sliding surfaces, the
coating is consolidated during the running-in period, and consequently no machining allowance is normally
made for phosphating.
6.5 Stress-relief heat treatment before cleaning and phosphating
Steel parts that have an ultimate tensile strength equal to or greater than 1 000 MPa and that contain tensile
stresses caused by machining, grinding, straightening or cold-forming operations shall be given a stress-relief
heat treatment, prior to cleaning and phosphating, and the procedures and classes for stress-relief heat
treatment shall be in accordance with ISO 9587, unless otherwise specified by the purchaser.
When a heat treatment for stress relief prior to phosphating is specified, the time and temperature of the heat
treatment process shall be included in the coating designation, as illustrated in 5.3.
Steels with oxide or scale have to be cleaned before application of the coatings. For high-strength steels
(equal to or greater than 1 000 MPa), non-electrolytic alkaline and anodic alkaline cleaners, as well as
mechanical cleaning procedures, are preferred to avoid the risk of producing hydrogen embrittlement during
cleaning procedures.
6.6 Hydrogen-embrittlement-relief heat treatment after phosphating
Steel parts having an ultimate tensile strength equal to or greater than 1 000 MPa, as well as surface-
hardened parts, shall receive hydrogen-embrittlement heat treatment according to the procedures and classes
of ISO 9588, unless otherwise specified by the purchaser.
Any heat treatment for the relief of hydrogen embrittlement shall be carried out before application of any
supplementary cover.
When a heat treatment for hydrogen-embrittlement relief after phosphating is specified, the time and
temperature of the heat treatment process shall be included in the coating designation, as illustrated in 5.3.
The effectiveness of the hydrogen-embrittlement-relief treatment is determined by test methods described in
[4]
ISO 10587 and ISO 15724, unless otherwise specified by the purchaser.
Embrittlement relief heat treatment at higher temperatures may cause colour changes and dehydration of
phosphate coatings with consequent lowering of corrosion resistance.
6.7 Treatments for supplementary coatings
Where the items are required to be finished by varnish, lacquer, or organic coating systems, and an interval
between the phosphating and the first stage of the treatment for supplementary coating is unavoidable, the
phosphated items shall be kept under conditions which preclude contamination or condensation of moisture
on the surface.
8 © ISO 2010 – All rights reserved

ISO 9717:2010(E)
Immediately after rinsing, drying, and the embrittlement-relief heat treatment where applied, the phosphate
coating is sealed by the application of a supplementary coating (see Table F.1). The type of coating required
(e.g. oil, grease, organic coating, etc.) and, in the case of varnish, lacquer, or organic coatings, the mass or
thickness of the coating, shall be as agreed by the purchaser [see 4.1 e) and 4.1 i)].
When heavily pigmented organic coatings are applied to a Class 1 or Class 2 phosphate coating, complete
impregnation may not be achieved, leading to a serious lack of adhesion, particularly under dynamic
conditions. When such phosphate films are given treatments for supplementary coating, consideration should
be given to using a low-viscosity impregnating coat of clear lacquer compatible with the normal organic
coating system, followed by the normal coating system.
6.8 Adhesion of phosphate conversion coatings
When the function of the phosphate conversion coating is corrosion resistance, an ancillary treatment is
always required. Guidance for phosphate conversion coatings to ensure good adhesion of organic coatings,
varnishes and related finishes, and to improve corrosion resistance of the basis metal, is given in Annex A.
If phosphated components are to be given organic coating systems, varnishes or similar coatings, they shall
first be rinsed in clean tap water and then preferably in deionized water, so as to ensure that the surfaces are
free from any water-soluble residues from previous processing, etc., which could give rise to blister formation
in the applied film. It is equally important that the phosphated surface intended to have organic coatings shall
be free of additional contamination, such as dust or finger prints.
6.9 Quality-evaluation test of phosphate conversion coatings
For applications suitable for intense local action rather than that produced by a continuous moving moisture
film, the salt droplet test (see Annex D and Reference [1] in the Bibliography) shall be used, unless otherwise
specified by the purchaser [see 4.1 j)].
For a test method to provide a means of controlling the continuity and quality of the coating by a continuous
moving moisture film, use the neutral salt spray (Fog) test method (see Annex E and References [2] and [7] in
the Bibliography), unless otherwise specified by the purchaser [see 4.1 j)].
In all cases, the minimum exposure time before the first appearance of the corrosion product of the substrate,
mode of assessment and whether removal of supplementary coatings is needed prior to examination of tested
specimens shall be specified by the purchaser [see 4.1 j)].
Depending on the composition of the material used for supplementary coating, considerable scatter of
exposure times can occur before the first appearance of corrosion. Therefore, minimum exposure time shall
always be specified for the supplementary coating.
Salt droplet and neutral salt spray (fog) tests provide means of controlling the continuity and quality of the
coatings and are not corrosion tests on metals.
The duration and results of these tests may bear little relationship to the service life of the finished article and,
therefore, the results obtained shall not be regarded as a direct guide to the resistance to exposure to an
aggressive atmosphere of the tested coatings in all environments where these coatings may be used.
Additionally, performance of different materials in the test shall not be taken as a direct guide to the relative
resistance to aggressive environments of these materials in service.
7 Sampling
The sampling method shall be selected from the procedures specified in ISO 2859 or ISO 4519, unless
otherwise specified by the purchaser [see 4.1 k)]. The purchaser shall specify the acceptance levels.
ISO 9717:2010(E)
Annex A
(informative)
Methods of application, characteristics and
significance of phosphate conversion coatings
A.1 General
Phosphate conversion coatings are produced by treatment with solutions, the main constituents of which are
the appropriate dihydrogen orthophosphates. All phosphate conversion coatings are more or less porous but
can be sealed significantly by appropriate sealing and supplementary treatments.
A.2 Methods of application
Phosphating is usually carried out by immersing the component in a coating bath, with agitation of the solution
if necessary, or by copious application or spraying of the component with the coating solution. Roller
application may, however, be used in the case of galvanized or ungalvanized steel strip.
In the case of certain low alloy steels, e.g. chromium-molybdenum-vanadium and copper-silicon-molybdenum-
vanadium steels, the best phosphate coatings are obtained using accelerated solutions. In the past,
considerable difficulties were experienced in obtaining acceptable phosphate coatings on some of these types
of st
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