SIST EN ISO 8251:2012
(Main)Anodizing of aluminium and its alloys - Measurement of abrasion resistance of anodic oxidation coatings (ISO 8251:2011)
Anodizing of aluminium and its alloys - Measurement of abrasion resistance of anodic oxidation coatings (ISO 8251:2011)
This International Standard specifies the following three test methods: a) abrasive-wheel-wear test method, determining the wear resistance and the wear index of anodic oxidation coatings on flat specimens of aluminium and its alloys; b) abrasive jet test method, comparing the resistance to abrasion of anodic oxidation coatings on aluminium and its alloys with that of a standard specimen or, alternatively, a reference specimen, by use of a jet of abrasive particles; c) falling sand abrasion method, determining the abrasion resistance with falling sand applied to thin anodic oxidation coatings. The use of these methods for coatings produced by hard anodizing is described in ISO 10074.
Anodisieren von Aluminium und Aluminiumlegierungen - Messung der Abriebfestigkeit von anodisch erzeugten Oxidschichten (ISO 8251:2011)
Diese Internationale Norm legt die folgenden drei Prüfverfahren fest:
a) Abriebprüfverfahren mit Schleifscheibe, das die Abriebfestigkeit und die Abriebzahl von anodisch
erzeugten Oxidschichten auf flachen Proben aus Aluminium und Aluminiumlegierungen ermittelt;
b) Abriebprüfverfahren mit Schleifmittelstrahl, das die Abriebfestigkeit von anodisch erzeugten
Oxidschichten auf Aluminium und Aluminiumlegierungen mit der Abriebfestigkeit entweder einer Normprobe
oder einer Referenzprobe vergleicht, mithilfe eines Strahls von Schleifmitteln;
c) Abriebprüfverfahren mit fallendem Sand, das die Abriebfestigkeit mithilfe von fallendem Sand
bestimmt und für dünne, anodisch erzeugte Oxidschichten anwendbar ist.
Die Anwendung dieser Verfahren an Schichten, die durch Hartanodisieren erzeugt wurden, ist in ISO 10074
beschrieben.
Anodisation de l'aluminium et de ses alliages - Détermination de la résistance à l'usure et de l'indice d'usure des couches d'oxyde anodiques (ISO 8251:2011)
L'ISO 8251:2011 spécifie les trois méthodes d'essai suivantes: a) méthode d'essai d'usure à la roue abrasive, qui détermine la résistance à l'usure et de l'indice d'usure de couches anodiques formées sur des échantillons plats d'aluminium ou d'un de ses alliages; b) méthode d'essai au jet abrasif, qui compare la résistance à l'abrasion de couches anodiques formées sur l'aluminium ou l'un de ses alliages avec celle d'un échantillon normalisé ou, en variante, celle d'un échantillon de référence, à l'aide d'un jet de particules abrasives; c) méthode d'abrasion par chute de sable, qui détermine la résistance à l'abrasion par chute de sable appliquée à des couches anodiques minces.
L'application de ces méthodes à des couches produites par anodisation dure est décrite dans l'ISO 10074.
Anodizacija aluminija in aluminijevih zlitin - Meritve obrabne obstojnosti anodno oksidiranih prevlek (ISO 8251:2011)
Ta mednarodni standard določa naslednje tri preskusne metode: a) metoda s preskusom obrabe z brusilnim kolutom, ki določa obrabno odpornost in obrabno število anodno oksidiranih prevlek na ploščatih vzorcih aluminija in njegovih zlitin; b) metoda s preskusom obrabe z brusilnim curkom, ki primerja obrabno odpornost anodno oksidiranih plasti na aluminiju in njegovih zlitinah z obrabno odpornostjo na standardnem vzorcu ali alternativno na referenčnem vzorcu z uporabo curka brusilnih delcev; c) brusilna metoda s padajočim peskom, ki določa obrabno odpornost s padajočim peskom, uporabljenim na tankih anodno oksidiranih prevlekah. Uporaba teh metod pri prevlekah, izdelanih s trdno anodizacijo, je opisana v ISO 10074.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 8251:2012
01-januar-2012
1DGRPHãþD
SIST EN 12373-10:1999
SIST EN 12373-9:1999
Anodizacija aluminija in aluminijevih zlitin - Meritve obrabne obstojnosti anodno
oksidiranih prevlek (ISO 8251:2011)
Anodizing of aluminium and its alloys - Measurement of abrasion resistance of anodic
oxidation coatings (ISO 8251:2011)
Anodisieren von Aluminium und Aluminiumlegierungen - Messung der Abriebfestigkeit
von anodisch erzeugten Oxidschichten (ISO 8251:2011)
Anodisation de l'aluminium et de ses alliages - Détermination de la résistance à l'usure et
de l'indice d'usure des couches d'oxyde anodiques (ISO 8251:2011)
Ta slovenski standard je istoveten z: EN ISO 8251:2011
ICS:
25.220.20 Površinska obdelava Surface treatment
77.120.10 Aluminij in aluminijeve zlitine Aluminium and aluminium
alloys
SIST EN ISO 8251:2012 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 8251:2012
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SIST EN ISO 8251:2012
EUROPEAN STANDARD
EN ISO 8251
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2011
ICS 25.220.20 Supersedes EN 12373-10:1998, EN 12373-9:1998
English Version
Anodizing of aluminium and its alloys - Measurement of abrasion
resistance of anodic oxidation coatings (ISO 8251:2011)
Anodisation de l'aluminium et de ses alliages - Anodisieren von Aluminium und Aluminiumlegierungen -
Détermination de la résistance à l'abrasion des couches Messung der Abriebfestigkeit von anodisch erzeugten
d'oxyde anodiques (ISO 8251:2011) Oxidschichten (ISO 8251:2011)
This European Standard was approved by CEN on 29 January 2011.
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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 8251:2011: E
worldwide for CEN national Members.
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SIST EN ISO 8251:2012
EN ISO 8251:2011 (E)
Contents Page
Foreword .3
2
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SIST EN ISO 8251:2012
EN ISO 8251:2011 (E)
Foreword
This document (EN ISO 8251:2011) has been prepared by Technical Committee ISO/TC 79 "Light metals and
their alloys" in collaboration with Technical Committee CEN/TC 132 “Aluminium and aluminium alloys” the
secretariat of which is held by AFNOR.
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 August 2011, and conflicting national standards shall be withdrawn at
the latest by August 2011.
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 12373-9:1998 and EN 12373-10:1998.
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, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 8251:2011 has been approved by CEN as a EN ISO 8251:2011 without any modification.
3
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SIST EN ISO 8251:2012
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SIST EN ISO 8251:2012
INTERNATIONAL ISO
STANDARD 8251
Second edition
2011-02-01
Anodizing of aluminium and its alloys —
Measurement of abrasion resistance of
anodic oxidation coatings
Anodisation de l'aluminium et de ses alliages — Détermination
de la résistance à l'abrasion des couches d'oxyde anodiques
Reference number
ISO 8251:2011(E)
©
ISO 2011
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SIST EN ISO 8251:2012
ISO 8251:2011(E)
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ii © ISO 2011 – All rights reserved
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SIST EN ISO 8251:2012
ISO 8251:2011(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Characteristics of abrasion tests.2
4.1 Abrasive-wheel-wear test .2
4.2 Abrasive jet test.2
4.3 Falling sand abrasion test .2
5 Abrasive-wheel-wear test .3
5.1 Principle .3
5.2 Apparatus.3
5.3 Procedure.3
5.4 Calculation of results.5
6 Abrasive jet test.8
6.1 Principle .8
6.2 Apparatus.8
6.3 Procedure.9
6.4 Calculation of results.11
7 Falling sand abrasion test .12
7.1 Principle .12
7.2 Apparatus.12
7.3 Test specimen.13
7.4 Test environment.13
7.5 Test conditions .13
7.6 Test procedure.13
7.7 Expression of results.14
8 Test report.15
Annex A (normative) Preparation of standard specimen .16
Annex B (informative) Depth survey of abrasion resistance.18
Annex C (informative) Design of abrasive-wheel-wear test apparatus .21
Annex D (informative) Design of abrasive jet test apparatus.22
Annex E (informative) Design of falling sand abrasion test apparatus.26
Bibliography.27
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SIST EN ISO 8251:2012
ISO 8251:2011(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 8251 was prepared by Technical Committee ISO/TC 79, Light metals and their alloys, Subcommittee
SC 2, Organic and anodic oxidation coatings on aluminium.
This second edition cancels and replaces the first edition (ISO 8251:1987) as well as ISO 8252:1987, which
have been technically revised.
The main changes compared to the first edition are as follows:
a) the inclusion of the test previously described in ISO 8252:1987;
b) the inclusion of the falling sand test;
c) the use of the methods for coatings produced by hard anodizing has been moved to ISO 10074:2010.
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SIST EN ISO 8251:2012
ISO 8251:2011(E)
Introduction
The resistance of anodic oxidation coatings to abrasion is an important property. As it is dependent upon the
composition of the metal, the thickness of the coating and the conditions of anodizing and sealing, it can give
information about the quality of the coating, its potential resistance to erosion or wear and its performance in
service. For example, the effect of an abnormally high anodizing temperature, which could cause potential
deterioration in service by chalking of the surface layers, may be readily detected by means of an abrasive
wear resistance test.
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SIST EN ISO 8251:2012
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SIST EN ISO 8251:2012
INTERNATIONAL STANDARD ISO 8251:2011(E)
Anodizing of aluminium and its alloys — Measurement
of abrasion resistance of anodic oxidation coatings
1 Scope
This International Standard specifies the following three test methods:
a) abrasive-wheel-wear test method, determining the wear resistance and the wear index of anodic
oxidation coatings on flat specimens of aluminium and its alloys;
b) abrasive jet test method, comparing the resistance to abrasion of anodic oxidation coatings on
aluminium and its alloys with that of a standard specimen or, alternatively, a reference specimen, by use
of a jet of abrasive particles;
c) falling sand abrasion method, determining the abrasion resistance with falling sand applied to thin
anodic oxidation coatings.
The use of these methods for coatings produced by hard anodizing is described in ISO 10074.
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 565:1990, Test sieves — Metal wire cloth, perforated metal plate and electroformed sheet — Nominal
sizes of openings
ISO 2360:2003, Non-conductive coatings on non-magnetic electrically conductive basis materials —
Measurement of coating thickness — Amplitude-sensitive eddy-current method
ISO 6344-1, Coated abrasives ― Grain size analysis ― Part 1: Grain size distribution test
ISO 8486-1:1996, Bonded abrasives — Determination and designation of grain size distribution — Part 1:
Macrogrits F4 to F220
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
test specimen
specimen on which the test is to be carried out
3.2
standard specimen
test specimen produced in accordance with the conditions specified in Annex A
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SIST EN ISO 8251:2012
ISO 8251:2011(E)
3.3
reference specimen
test specimen produced under conditions agreed between the anodizer and the customer
3.4
double stroke
ds
one complete reciprocal movement made by the abrasive wheel
4 Characteristics of abrasion tests
There are three kinds of abrasion tests: abrasive-wheel-wear test, abrasive jet test and falling sand abrasion
test.
4.1 Abrasive-wheel-wear test
Determination of the resistance to abrasion by movement of a test specimen relative to an abrasive paper
under a specified pressure. The wear resistance or the wear index of the layers of oxide near the surface, or
of the whole oxidation coating thickness, or of any selected intermediate zone may be determined by the
method described. For most purposes the wear index (see 5.4.3) or the mass wear index (see 5.4.4) will be
the most appropriate characteristic to determine.
The method is applicable to all anodic oxidation coatings of thickness more than 5 μm on flat aluminium or its
alloy specimens.
This method is not applicable to concave or convex specimens; these may be examined using the abrasive jet
test method which will give an average value for the abrasive resistance of the coating (see 4.2 and Clause 6).
NOTE Minimum test specimen dimensions of 50 mm × 50 mm are normally required.
4.2 Abrasive jet test
Determination of the resistance to abrasion by the impact of abrasive particles projected onto a test specimen.
The mean specific abrasion resistance of anodic oxidation coatings may be determined.
NOTE 1 Different batches of the same abrasive are liable to give different results and for this reason the test is a
comparative one.
NOTE 2 With a suitably designed abrasive jet and film-thickness-measuring devices with a small probe, it is possible to
conduct a depth survey which indicates how abrasion resistance varies through the coating thickness (see Annex B).
However, this property is preferably measured using the abrasive-wheel-wear test.
The method described is applicable to all anodic oxidation coatings of thickness more than 5 μm on aluminium
or its alloys. It is primarily intended for surfaces which are not flat. If suitable flat test surfaces are available,
the abrasive-wheel-wear test is the preferred method. Production components may be tested without cutting if
the apparatus chamber can accommodate these.
NOTE 3 This method is particularly suitable for small test specimens because the individual test area required is only
about 2 mm in diameter.
4.3 Falling sand abrasion test
Determination of the resistance to abrasion by the impact of freely falling abrasive particles onto anodic
oxidation coatings.
The method described is applicable to the thin anodic oxidation coatings.
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SIST EN ISO 8251:2012
ISO 8251:2011(E)
5 Abrasive-wheel-wear test
5.1 Principle
The anodic oxidation coatings on a test specimen are abraded, under defined conditions, by reciprocal motion
against a strip of silicon carbide paper attached to the outer circumference of a wheel. After each double
stroke, the wheel turns through a small angle to bring an unused portion of the abrasive strip into contact with
the test area. The decrease in coating thickness or mass obtained is used to calculate the wear resistance or
wear index. This result is compared with that obtained using a standard specimen (see Annex A) or reference
specimen (see 3.3).
The method normally requires an eddy-current meter with a probe of less than 12 mm diameter. If this is not
available, the method of loss in mass should be used.
NOTE A complete presentation of the wear characteristics of the anodic oxidation coatings can be obtained by
progressively abrading the test area, until the substrate metal is revealed, and then constructing a graph to show the
relation between the coating thickness removed and the number of double strokes used. This is referred to as a depth
survey of the anodic oxidation coatings (see Annex B).
The testing environment should be at room temperature and the relative humidity should be under 65 %.
5.2 Apparatus
5.2.1 Abrasive-wheel-wear test apparatus
The apparatus consists of a clamping device or pressure plate for holding the test specimen (see 5.3.2) level
and rigid, and a 50 mm diameter wheel to the outer circumference of which is attached a 12 mm wide strip of
silicon carbide paper (see 5.2.2). The force between the wheel and the test surface shall be capable of being
varied from zero to at least 4,9 N with an accuracy of ±0,05 N. The abrasive action is produced either by the
fixed wheel sliding to and fro in a horizontal plane in parallel contact with the test surface over a 30 mm length
or, alternatively, by the test specimen sliding in a similar way over the stationary wheel. Typical apparatus is
illustrated in Figure C.1.
After each double stroke, the wheel is advanced through a small angle to bring a fresh area of the silicon
carbide paper into contact with the surface before making the next double stroke. The angle of rotation is such
that, after 400 ds, the wheel will have made one complete revolution. At this stage, the strip of silicon carbide
paper shall be renewed. The relative speed of movement shall be (40 ± 2) ds per minute. The number of
double strokes can be registered by means of a counter, and provision is normally made for the apparatus to
switch off automatically after a preset number of double strokes has been reached (400 ds maximum). The
test surface shall be kept free from loose powder or abrasion detritus during the test.
5.2.2 Abrasive strip
The abrasive strip consists of P320 silicon carbide paper (in accordance with ISO 6344-1) 12 mm wide. Its
length shall be such that it covers the abrasive wheel without overlapping, and it shall be either bonded or
mechanically clamped into position.
NOTE P320 paper is 45 μm grade (320 mesh).
5.2.3 Eddy-current meter
An eddy-current meter with a suitable diameter probe is described in ISO 2360.
5.3 Procedure
5.3.1 Standard specimen
Prepare the standard specimen using the method specified in Annex A.
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SIST EN ISO 8251:2012
ISO 8251:2011(E)
5.3.2 Test specimen
Cut a suitably sized test specimen from the item to be tested without damaging the area to be tested.
Test dimensions of 50 mm × 50 mm are usually required.
5.3.3 Calibration of apparatus
5.3.3.1 Select and mark the area of the standard specimen (see 5.3.1) to be abraded. Accurately
measure the anodic oxidation coating thicknesses in each of at least three positions along the test area by
means of the eddy-current meter (see 5.2.3) in accordance with the method specified in ISO 2360 and
calculate an average thickness value (d ).
1
5.3.3.2 Clamp the standard specimen into position on the apparatus (see 5.2.1).
5.3.3.3 Attach a new strip of silicon carbide paper (see 5.2.2) to the circumference of the abrasive wheel.
Adjust the abrasive wheel, in accordance with the manufacturer’s instructions, so that it gives uniform
abrasion across the width of the test area. Adjust the force between the wheel and the test surface to
3,9 N ± 0,1 N.
5.3.3.4 Allow the apparatus to run for 400 ds or an adequate number of double strokes corresponding to
the coating thickness and the kind of aluminium alloys. Keep the abrasive action uniform by adjusting and
maintaining the alignment of the abrasive wheel in accordance with the manufacturer's instructions.
Continuously remove any abrasion detritus by suction, blowing or frequent wiping with a fine brush.
5.3.3.5 Remove the standard specimen from the apparatus, wipe carefully to remove any loose oxide
and determine the average thickness of the coating at the test area (d ) using the eddy-current meter in
2
accordance with 5.3.3.1.
A 3 mm length at one extremity of the test area may be subject to extra wear because of the continual wheel
rotation which takes place at this point; this area should be ignored when taking the thickness measurements.
5.3.3.6 Carry out at least two further determinations on the standard specimen in test areas that do not
overlap, using the procedure specified in 5.3.3.1 to 5.3.3.5.
5.3.3.7 Calculate the wear rate for the standard specimen (see 5.4.3) from the average of the
determinations.
5.3.4 Determination
Take the test specimen (see 5.3.2) and carry out the procedure specified in 5.3.3.1 to 5.3.3.6 using abrasive
strips from the same batch as that used for the calibration. If the test specimen is not rigid, bond it firmly with
an adhesive to a rigid metal sheet with a flat surface before carrying out the determination.
Calculate the wear rate for the test specimen and, from the wear rates for the standard specimen and for the
test specimen, calculate the wear index in accordance with 5.4.3.
5.3.5 Use of a reference specimen
5.3.5.1 General
Because of the relatively high abrasion resistance of integral colour anodized specimens, testing of these
finishes normally requires the use of a reference specimen produced by the same process (see 3.3) in a
comparative-wear-testing method (see 5.3.6).
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SIST EN ISO 8251:2012
ISO 8251:2011(E)
5.3.5.2 Initial determination
Carry out an initial determination in accordance with 5.3.4. If the thickness loss in the test area is less than
3 μm, adjust the abrasion conditions either by increasing the force between the wheel and the test specimen
surface, or by employing a coarser grade of silicon carbide paper. Alternatively, an increased number of
double strokes may be used.
Unless a depth survey is being carried out (see Annex B), the abrasion conditions should be adjusted to give
a coating thickness loss of (5 ± 3) μm after 400 ds. If loss of mass is to be determined, the mass equivalent of
(5 ± 3) μm coating thickness is required to be known. This necessitates an assumption to be made about the
coating density or, alternatively, this should be estimated by means of ISO 2106.
5.3.5.3 Determination
Determine the loss in thickness or loss in mass of the test specimen and the reference specimen under the
conditions established in 5.3.5.2, following the procedure specified in 5.3.6.
Calculate the comparative wear rate in accordance with 5.4.5, or the comparative mass wear rate in
accordance with 5.4.6, as appropriate.
5.3.6 Comparative wear testing
5.3.6.1 General
Comparison of the abrasion of the test specimen (see 5.3.2) can be made with that of a reference specimen
(see 3.3) or with the standard specimen (see 3.2). In these cases, either comparative loss in thickness or
comparative loss in mass can be determined. The comparative wear rate is expressed as a percentage of that
of the reference specimen.
5.3.6.2 Comparative loss of thickness
Determine the loss in thickness of the test specimen and of the reference specimen using the procedure
specified in 5.3.4.
Calculate the comparative wear rate in accordance with 5.4.5.
5.3.6.3 Comparative loss of mass
5.3.6.3.1 Select and mark the area of the test specimen to be abraded. Weigh the test specimen to the
nearest 0,1 mg (m ). Carry out the procedure specified in 5.3.3.2 to 5.3.3.4.
1
5.3.6.3.2 Remove the test specimen from the apparatus, wipe to remove any loose oxide and weigh to the
nearest 0,1 mg (m ).
2
Carry out at least two further determinations on the test specimen in test areas that do not overlap.
NOTE Freshly exposed anodic oxidation coatings can gain in mass by absorbing water vapour. Multiple tests on a
single panel can therefore be subject to errors dependent upon variations in atmospheric humidity.
5.3.6.3.3 Repeat the procedure specified in 5.3.6.3.1 and 5.3.6.3.2 on the reference specimen. Calculate
the comparative mass wear rate in accordance with 5.4.6.
5.4 Calculation of results
The calculation of results shall be chosen from the following.
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SIST EN ISO 8251:2012
ISO 8251:2011(E)
5.4.1 Wear resistance
Calculate the wear resistance, WR, in double strokes per micrometre, using Equation (1):
400
WR= (1)
dd−
12
where
d is the average thickness, in micrometres, before abrasion (see 5.3.3.1);
1
d is the average thickness, in micrometres, after 400 ds abrasion (see 5.3.3.5).
2
5.4.2 Wear resistance coefficient
Calculate the wear resistance coefficient, WRC, using Equation (2):
WR dd−
t1s 2s
WRC== (2)
WR dd−
s1t 2t
where
W
...
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