Fine ceramics (advanced ceramics, advanced technical ceramics) -- Methods for evaluating wear and friction characteristics of fine ceramic thin films under dry and humid conditions

This document specifies a method for testing the wear resistance and friction coefficient for fine ceramic thin films in dry and high-humidity environments, where such films have a thickness of up to approximately 1 µm and are deposited on a substrate or a base, including a thin substrate or a very thin organic polymer film base.

Céramiques techniques -- Méthodes pour l'évaluation des caractéristiques d'usure et de frottement des films minces de céramiques techniques en conditions sèches et humides

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Publication Date
23-Aug-2021
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5060 - Close of voting Proof returned by Secretariat
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08-Jul-2021
Completion Date
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INTERNATIONAL ISO
STANDARD 23737
First edition
2021-08
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Methods for evaluating wear and
friction characteristics of fine ceramic
thin films under dry and humid
conditions
Céramiques techniques — Méthodes pour l'évaluation des
caractéristiques d'usure et de frottement des films minces de
céramiques techniques en conditions sèches et humides
Reference number
ISO 23737:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO 23737:2021(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: 2 ----------------------
ISO 23737:2021(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

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

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

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

4 Test specimens........................................................................................................................................................................................................ 2

5 Measurement principle ................................................................................................................................................................................. 2

6 Testing room environment ........................................................................................................................................................................ 2

7 Wear formation test apparatus ............................................................................................................................................................. 3

8 Test specimen preparation ........................................................................................................................................................................ 5

9 Test specimen pretreatment .................................................................................................................................................................... 5

9.1 General ........................................................................................................................................................................................................... 5

9.2 Test specimen cleaning .................................................................................................................................................................... 5

9.3 Test specimen drying ......................................................................................................................................................................... 5

10 Environmental conditions for the formation of the wear and the evaluation of

friction coefficient ............................................................................................................................................................................................... 6

10.1 General ........................................................................................................................................................................................................... 6

10.2 Dry environment ................................................................................................................................................................................... 6

10.3 High-humidity environment ....................................................................................................................................................... 6

11 Wear motion conditions ............................................................................................................................................................................... 6

11.1 Reciprocating wear conditions ................................................................................................................................................. 6

11.2 Rotating disc wear conditions ................................................................................................................................................... 7

12 E valuation of wear track cross-section formed on thin film test specimen surface ......................8

13 Evaluation of volume of worn portion on indenter ball surface .........................................................................8

13.1 General ........................................................................................................................................................................................................... 8

13.2 Observation of indenter ball wear surface profile ................................................................................................... 8

13.3 Calculation of volume of worn portion on indenter ball surface ................................................................. 9

14 Investigations of morphology and elemental distribution maps for wear tracks on

thin film test specimens and worn sections on indenter balls ............................................................................9

14.1 General ........................................................................................................................................................................................................... 9

14.2 Observation of the morphology ............................................................................................................................................... 9

14.3 Investigations of elemental distribution maps ........................................................................................................10

15 Calculation of friction coefficient .....................................................................................................................................................10

16 Testing procedures ..........................................................................................................................................................................................10

16.1 Measurement of thickness of thin film test specimen .......................................................................................10

16.2 Thin film test specimen preparation and cleaning ...............................................................................................10

16.3 Setting of wear formation conditions ...............................................................................................................................10

16.3.1 General...................................................................................................................................................................................10

16.3.2 Wear formation conditions for a dry environment .........................................................................11

16.3.3 Wear formation conditions for a high-humidity environment .............................................11

16.4 Wear formation ....................................................................................................................................................................................11

16.4.1 Start of wear formation on the thin film test specimen ..............................................................11

16.4.2 Friction force measurement ................................................................................................................................11

16.5 E valuation of thin film test specimen surface and indenter ball surface after wear

formation ..................................................................................................................................................................................................11

16.5.1 General...................................................................................................................................................................................11

16.5.2 Measurement of wear track cross-section on thin film test specimen ..........................11

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 23737:2021(E)

16.5.3 Evaluation of volume of worn portion on indenter ball surface ..........................................11

16.5.4 Investigations of morphology and elemental distribution maps ........................................11

16.6 Calculation of friction coefficient .........................................................................................................................................11

17 Precautions for summarization of test results ..................................................................................................................12

18 Test report ................................................................................................................................................................................................................12

Annex A (informative) Example of reciprocating slide wear results and rotating slide wear

results ...........................................................................................................................................................................................................................13

Annex B (informative) Method of holding polymer film or thin glass plate with a thickness

of < 200 µm in sliding wear formations ....................................................................................................................................15

Annex C (informative) Effects of combining thin film materials and indenter materials

in sliding wear tests........................................................................................................................................................................................17

Annex D (informative) Investigation of optimal load for indenter ....................................................................................22

Annex E (informative) Quantification of wear track cross-section area ......................................................................24

Annex F (informative) Examples of investigations of morphology and elemental

distribution maps for wear tracks on thin films and worn sections of indenter balls .............25

Bibliography .............................................................................................................................................................................................................................30

iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 23737:2021(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 206, Fine ceramics.

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.
© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO 23737:2021(E)
Introduction

Fine ceramic thin films are used in a wide variety of applications, such as sensors, actuators or other

micromechanical elements; display elements; memory elements; recording media; optical elements;

packaging films; and films and glass for building construction and vehicles. In the industrial application

of fine ceramic thin films, resistance to wear is an important index for evaluation. The resistance

to wear of fine ceramic thin films is greatly affected by environmental humidity and the humidity

history of the thin film. Fine ceramic thin films are also used in different humidity environments,

necessitating standards for the evaluation of wear resistance and the friction coefficient under a

wide humidity range. Standards published to date concerning wear resistance testing assume only

a temperature environment of 23 °C and a relative humidity of 50 %; the thickness of the thin films

subject to evaluation is also comparatively large, at several to 10 µm. These testing procedures are

inappropriate for evaluating the wear resistance of fine ceramic thin films that have a thickness of up

to approximately 1 µm and are applied for electronic and optical devices, because the wear resistance

for a smaller indentation load is affected by the relative humidity of the test environment, i.e. the

mechanisms employed in the wear test for fine ceramic thin films with a smaller indentation load are

strongly affected by the relative humidity of the test environment. Therefore, the wear test for fine

ceramic thin films should be performed under a regulated relative humidity condition. This document

provides measurement methods that facilitate the accurate evaluation of wear resistance for fine

ceramic thin films in dry and high-humidity environments, where such films have a thickness of up

to approximately 1 µm and are deposited on a thin substrate or an organic polymer film base. This

document has been enacted to facilitate industrial development through the prompt dissemination of

these measurement methods.
vi © ISO 2021 – All rights reserved
---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO 23737:2021(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Methods for evaluating wear and friction
characteristics of fine ceramic thin films under dry and
humid conditions
1 Scope

This document specifies a method for testing the wear resistance and friction coefficient for fine

ceramic thin films in dry and high-humidity environments, where such films have a thickness of up to

approximately 1 µm and are deposited on a substrate or a base, including a thin substrate or a very thin

organic polymer film base.
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 3274, Geometrical Product Specifications (GPS) — Surface texture: Profile method — Nominal

characteristics of contact (stylus) instruments

ISO 13565-1, Geometrical Product Specifications (GPS) — Surface texture: Profile method; Surfaces having

stratified functional properties — Part 1: Filtering and general measurement conditions

ISO 13565-2, Geometrical Product Specifications (GPS) — Surface texture: Profile method; Surfaces having

stratified functional properties — Part 2: Height characterization using the linear material ratio curve

ISO 20507, Fine ceramics (advanced ceramics, advanced technical ceramics) — Vocabulary

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 20507 and the following apply.

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

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
wear

phenomenon leading to progressive loss or progressive displacement from the surface of a solid

material due to motion relative to a contacting body
3.2
frictional force

resistive force exerted on an opposing body when bodies in contact move or tend to slide against each

other
3.3
friction coefficient
dimensionless ratio of frictional force to the normal force applied
© ISO 2021 – All rights reserved 1
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ISO 23737:2021(E)
3.4
wear test

test for evaluating friction and wear characteristics caused by sliding contact motion

Note 1 to entry: In a narrow sense, the term “wear test” implies the process of wear formation on the test

specimen due to a sliding motion; in a broad sense, it implies procedures such as specimen preparation, wear

formation, friction coefficient measurements, and evaluations of the wear track and the worn portion formed on

the counter material.
3.5
drying chamber

hermetically sealed vessel for eliminating moisture on a test specimen surface while the test specimen

remains held in a vacuum
3.6
relative humidity

ratio of water vapour partial pressure to saturated vapour pressure at a given temperature

3.7
dry air
air with a dew point of −60 °C or lower at an absolute pressure of 101,3 kPa
3.8
dry nitrogen

nitrogen with a dew point of −60 °C or lower at an absolute pressure of 101,3 kPa

4 Test specimens

Use fine ceramic thin films that have a thickness of up to approximately 1 µm and are deposited on

a silicon wafer, glass, organic polymer film or other such substrate or base. Provided that the test

specimens can be fitted on a wear testing apparatus as described in this document, the test specimen

dimensions and shape are of no concern. However, the thickness in the area where the wear formation

is performed shall be uniform.
5 Measurement principle

The wear properties of ceramic thin films are greatly affected by environmental humidity and the

humidity history of the thin film. Consequently, the wear resistance of a thin film test specimen should

be evaluated accurately by measuring wear of the thin film test specimen in dry and high-humidity

environments.

A reciprocating wear formation method or a rotating disc wear formation method shall be used as the

method for evaluating wear. Details of the principles pertaining to a reciprocating wear test method

are given in EN 1071-12. Details of the principles pertaining to a rotating disc wear test method are

given in ISO 20808 and EN 1071-13.

This document addresses both methods, i.e. a reciprocating wear test method and a rotating disc wear

test method. Annex A provides an example of results from testing carried out using a reciprocating

wear test method and a rotating disc wear test method.
6 Testing room environment

Measurements shall be carried out in a location subject to minimal changes in temperature and

humidity. Specifically, testing shall be carried out under the following environmental conditions:

a) testing room temperature: (23 ± 2) °C;
b) testing room relative humidity: 70 % or lower.
2 © ISO 2021 – All rights reserved
---------------------- Page: 8 ----------------------
ISO 23737:2021(E)

NOTE If the temperature of the testing room is low, condensation can form on the wear evaluation apparatus.

7 Wear formation test apparatus

7.1 Reciprocating wear tester: The reciprocating wear tester shall consist of a test specimen

holder which retains a thin film test specimen, a drive apparatus which moves a thin film test specimen

reciprocally, a holder which retains and secures an indenter ball, a loading mechanism which applies a

constant load to the indenter ball, an equipment unit for detecting frictional force and a test environment

control sealing mechanism. Figure 1 shows a schematic of a test specimen holding system for a

reciprocating wear tester. Details concerning the reciprocal wear tester are given in EN 1071-12.

Key
1 indenter with a lateral force measurement system
2 test specimen
3 test specimen holder
4 wear track

Figure 1 — Schematic of a reciprocating wear tester (indicating the test specimen holding

system)

a) The test specimen holder shall move reciprocally within a horizontal plane and the deflection in

the direction of reciprocal motion shall be adjustable to 0,02 mm or less.

b) The drive apparatus shall allow for the setting of a predetermined sliding speed and changes in

the sliding speed due to variations in the frictional force shall be negligible. A reciprocating sliding

motion counter or equivalent device shall be included.

c) The indenter ball holder shall secure the indenter ball reliably against displacement by the frictional

force generated at the area of contact between the indenter ball and the test specimen, and shall

have high rigidity against induced stress.

d) The indenter ball loading mechanism shall apply and maintain a predetermined load either directly

or through a lever, and by means of a weight or a hydraulic or pressurized air system.

e) The frictional force detection equipment can be a load cell or a leaf spring strain measurement,

rotational torque measurement or other such measurement mechanism as desired, but its insertion

shall not affect the frictional conditions. The measurement precision for the frictional force shall

be within 1 % of the applied load. Use of an in situ linear wear measurement apparatus shall be

optional. If used, the apparatus shall have a depth resolution of less than 0,01 µm.

f) A sealing mechanism for controlling the test atmosphere shall be provided.

7.2 Rotating disc wear tester: The rotating disc wear tester shall consist of a test specimen holder

which retains a thin film test specimen, a drive apparatus which moves a thin film test specimen

rotationally, a holder which retains and secures an indenter ball, a loading mechanism which applies a

constant load to a thin film test specimen, a frictional force detection mechanism and a test environment

© ISO 2021 – All rights reserved 3
---------------------- Page: 9 ----------------------
ISO 23737:2021(E)

control sealing mechanism. Figure 2 shows a schematic of a test specimen holding system for a rotating

disc wear tester. Details concerning the rotating disc wear tester are given in ISO 20808.

Key
1 indenter with a lateral force measurement system
2 test specimen
3 test specimen holder
4 wear track

Figure 2 — Schematic of a rotating disk wear tester (indicating the test specimen holding

system)

a) The rotating disc holder shall rotate within a horizontal or vertical plane, the deflection of the

rotational axis shall be adjustable to 0,02 mm or less, and the deflection in the direction of the

rotational axis at the area of contact shall be adjustable to 0,05 mm or less.

b) The drive apparatus shall allow for the setting of a disc rotation speed that provides a predetermined

sliding speed, and changes in the rotational speed due to variations in the frictional force shall be

negligible. A rotational speed counter or equivalent device shall be included.

c) The indenter ball holder shall secure the indenter ball reliably against rotation or displacement

by the frictional force generated at the area of contact between the indenter ball and the disc test

specimen, and shall have high rigidity against induced stress.

d) The indenter ball loading mechanism shall apply and maintain a predetermined load either directly

or through a lever, and by means of a weight or a hydraulic or pressurized air system.

e) The frictional force detection mechanism can be a load cell or a leaf spring strain measurement,

rotational torque measurement, or other such measurement mechanism as desired, but its

insertion shall not affect the frictional conditions. The measurement precision for the frictional

force shall be within 1 % of the applied load. Use of an in situ linear wear measurement apparatus

shall be optional. If used, the apparatus shall have a depth resolution of less than 0,01 µm.

f) A sealing mechanism for controlling the testing environment shall be provided.

7.3 Thermo-hygrostat chamber: The item used shall allow for the setting of relative humidity within

the range of 30 % to 90 % at a temperature of 23 °C. A metal or plastic tube shall be used to introduce air

of a predetermined temperature and humidity into the wear test chamber.

7.4 Dew point meter: The item shall be a capacitance (impedance) hygrometer (dew point meter) or

a chilled mirror dew point meter. Details are given in JIS Z 8806.

7.5 Stylus profilometer: A stylus surface roughness measurement apparatus as specified in

ISO 13565-1 and ISO 13565-2 or one with an equivalent or better precision shall be used.

7.6 Laser interferometric profilometer: The apparatus used shall make use of interference in parallel

light beams with an aligned wave surface to measure the surface profile of a test specimen surface, based

on the interference produced by a phase difference between light reflected from the test piece surface

4 © ISO 2021 – All rights reserved
---------------------- Page: 10 ----------------------
ISO 23737:2021(E)

and light reflected from a reference surface serving as a standard. The apparatus used shall have a height

measurement resolution of approximately 10 nm at a magnification power of approximately 100× to

500×. A coherence scanning interferometry (CSI) system for three-dimensional mapping of surface

height is specified in ISO 25178-604.

7.7 Optical microscope: This apparatus shall magnify an object visually for observation using optical

lenses. The apparatus used shall have sufficient resolution at a magnification power of approximately

100× to 800×.

7.8 Scanning electron microscope: This microscope shall be equipped with a basic function for

forming a magnified image using an appropriate method, e.g. secondary electrons obtained from a test

specimen by two-dimensional scanning during irradiation of a test specimen with a tightly focused

electron beam. The apparatus used shall have sufficient resolution at an observational magnification

power of the order of 5 000×. For ceramic thin films, applying an electroconductive coating prior to the

observation is strongly recommended.

7.9 Energy dispersive X-ray spectroscopy: This instrument shall be equipped with an energy

dispersive X-ray (EDX) spectrometer to provide elemental identification by measuring the energy

of X-rays emitted from a specimen due to excitation by the primary electron beam. An elemental

distribution map can be acquired by combining the EDX signal with the position signal of the scanning

primary electron beam.

7.10 Drying chamber: Provided that the chamber can maintain an internal pressure of 4 kPa or lower

and a temperature of 130 °C or higher, its material, form and other details are not of concern.

7.11 Exhauster: A diaphragm pump or similar item shall be used. Provided that the item has an ultimate

pressure of 4 kPa or lower, its type shall not be of concern.
8 Test specimen preparation

Use the same lot or the same batch to prepare thin film test specimens as needed, allowing for

completion of at least three test runs.
9 Test specimen pretreatment
9.1 General

Pretreat test specimens as needed. If test specimens have been exposed to high humidity, for example

cleaned using wa
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23737
ISO/TC 206
Fine ceramics (advanced ceramics,
Secretariat: JISC
advanced technical ceramics) —
Voting begins on:
2021­05­12 Methods for evaluating wear and
friction characteristics of fine ceramic
Voting terminates on:
2021­07­07
thin films under dry and humid
conditions
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 23737:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. ISO 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 23737:2021(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
CH­1214 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: 2 ----------------------
ISO/FDIS 23737:2021(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

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

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

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

4 Test specimens........................................................................................................................................................................................................ 2

5 Measurement principle ................................................................................................................................................................................. 2

6 Testing room environment ........................................................................................................................................................................ 2

7 Wear formation test apparatus ............................................................................................................................................................. 3

8 Test specimen preparation ........................................................................................................................................................................ 5

9 Test specimen pretreatment .................................................................................................................................................................... 5

9.1 General ........................................................................................................................................................................................................... 5

9.2 Test specimen cleaning .................................................................................................................................................................... 5

9.3 Test specimen drying ......................................................................................................................................................................... 5

10 Environmental conditions for the formation of the wear and the evaluation of

friction coefficient ............................................................................................................................................................................................... 6

10.1 General ........................................................................................................................................................................................................... 6

10.2 Dry environment ................................................................................................................................................................................... 6

10.3 High-humidity environment ....................................................................................................................................................... 6

11 Wear motion conditions ............................................................................................................................................................................... 6

11.1 Reciprocating wear conditions ................................................................................................................................................. 6

11.2 Rotating disc wear conditions ................................................................................................................................................... 7

12 E valuation of wear track cross-section formed on thin film test specimen surface ......................8

13 Evaluation of volume of worn portion on indenter ball surface .........................................................................8

13.1 General ........................................................................................................................................................................................................... 8

13.2 Observation of indenter ball wear surface profile ................................................................................................... 8

13.3 Calculation of volume of worn portion on indenter ball surface ................................................................. 9

14 Investigations of morphology and elemental distribution maps for wear tracks on

thin film test specimens and worn sections on indenter balls ............................................................................9

14.1 General ........................................................................................................................................................................................................... 9

14.2 Observation of the morphology ............................................................................................................................................... 9

14.3 Investigations of elemental distribution maps ........................................................................................................10

15 Calculation of friction coefficient .....................................................................................................................................................10

16 Testing procedures ..........................................................................................................................................................................................10

16.1 Measurement of thickness of thin film test specimen .......................................................................................10

16.2 Thin film test specimen preparation and cleaning ...............................................................................................10

16.3 Setting of wear formation conditions ...............................................................................................................................10

16.3.1 General...................................................................................................................................................................................10

16.3.2 Wear formation conditions for a dry environment .........................................................................11

16.3.3 Wear formation conditions for a high-humidity environment .............................................11

16.4 Wear formation ....................................................................................................................................................................................11

16.4.1 Start of wear formation on the thin film test specimen ..............................................................11

16.4.2 Friction force measurement ................................................................................................................................11

16.5 E valuation of thin film test specimen surface and indenter ball surface after wear

formation ..................................................................................................................................................................................................11

16.5.1 General...................................................................................................................................................................................11

16.5.2 Measurement of wear track cross-section on thin film test specimen ..........................11

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 23737:2021(E)

16.5.3 Evaluation of volume of worn portion on indenter ball surface ..........................................11

16.5.4 Investigations of morphology and elemental distribution maps ........................................11

16.6 Calculation of friction coefficient .........................................................................................................................................11

17 Precautions for summarization of test results ..................................................................................................................12

18 Test report ................................................................................................................................................................................................................12

Annex A (informative) Example of reciprocating slide wear results and rotating slide wear

results ...........................................................................................................................................................................................................................13

Annex B (informative) Method of holding polymer film or thin glass plate with a thickness

of < 200 µm in sliding wear formations ....................................................................................................................................15

Annex C (informative) Effects of combining thin film materials and indenter materials

in sliding wear tests........................................................................................................................................................................................17

Annex D (informative) Investigation of optimal load for indenter ....................................................................................22

Annex E (informative) Quantification of wear track cross-section area ......................................................................24

Annex F (informative) Examples of investigations of morphology and elemental

distribution maps for wear tracks on thin films and worn sections of indenter balls .............25

Bibliography .............................................................................................................................................................................................................................30

iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 23737:2021(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 non­governmental, 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 206, Fine ceramics.

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.
© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO/FDIS 23737:2021(E)
Introduction

Fine ceramic thin films are used in a wide variety of applications, such as sensors, actuators or other

micromechanical elements; display elements; memory elements; recording media; optical elements;

packaging films; and films and glass for building construction and vehicles. In the industrial application

of fine ceramic thin films, resistance to wear is an important index for evaluation. The resistance

to wear of fine ceramic thin films is greatly affected by environmental humidity and the humidity

history of the thin film. Fine ceramic thin films are also used in different humidity environments,

necessitating standards for the evaluation of wear resistance and the friction coefficient under a

wide humidity range. Standards published to date concerning wear resistance testing assume only

a temperature environment of 23 °C and a relative humidity of 50 %; the thickness of the thin films

subject to evaluation is also comparatively large, at several to 10 µm. These testing procedures are

inappropriate for evaluating the wear resistance of fine ceramic thin films that have a thickness of up

to approximately 1 µm and are applied for electronic and optical devices, because the wear resistance

for a smaller indentation load is affected by the relative humidity of the test environment, i.e. the

mechanisms employed in the wear test for fine ceramic thin films with a smaller indentation load are

strongly affected by the relative humidity of the test environment. Therefore, the wear test for fine

ceramic thin films should be performed under a regulated relative humidity condition. This document

provides measurement methods that facilitate the accurate evaluation of wear resistance for fine

ceramic thin films in dry and high-humidity environments, where such films have a thickness of up

to approximately 1 µm and are deposited on a thin substrate or an organic polymer film base. This

document has been enacted to facilitate industrial development through the prompt dissemination of

these measurement methods.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23737:2021(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Methods for evaluating wear and friction
characteristics of fine ceramic thin films under dry and
humid conditions
1 Scope

This document specifies a method for testing the wear resistance and friction coefficient for fine

ceramic thin films in dry and high-humidity environments, where such films have a thickness of up to

approximately 1 µm and are deposited on a substrate or a base, including a thin substrate or a very thin

organic polymer film base.
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 13565­1, Geometrical Product Specifications (GPS) — Surface texture: Profile method; Surfaces having

stratified functional properties — Part 1: Filtering and general measurement conditions

ISO 13565­2, Geometrical Product Specifications (GPS) — Surface texture: Profile method; Surfaces having

stratified functional properties — Part 2: Height characterization using the linear material ratio curve

ISO 20507, Fine ceramics (advanced ceramics, advanced technical ceramics) — Vocabulary

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 20507 and the following apply.

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/
3.1
wear

phenomenon leading to progressive loss or progressive displacement from the surface of a solid

material due to motion relative to a contacting body
3.2
frictional force

resistive force exerted on an opposing body when bodies in contact move or tend to slide against each

other
3.3
friction coefficient
dimensionless ratio of frictional force to the normal force applied
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ISO/FDIS 23737:2021(E)
3.4
wear test

test for evaluating friction and wear characteristics caused by sliding contact motion

Note 1 to entry: In a narrow sense, the term “wear test” implies the process of wear formation on the test

specimen due to a sliding motion; in a broad sense, it implies procedures such as specimen preparation, wear

formation, friction coefficient measurements, and evaluations of the wear track and the worn portion formed on

the counter material.
3.5
drying chamber

hermetically sealed vessel for eliminating moisture on a test specimen surface while the test specimen

remains held in a vacuum
3.6
relative humidity

ratio of water vapour partial pressure to saturated vapour pressure at a given temperature

3.7
dry air
air with a dew point of −60 °C or lower at an absolute pressure of 101,3 kPa
3.8
dry nitrogen

nitrogen with a dew point of −60 °C or lower at an absolute pressure of 101,3 kPa

4 Test specimens

Use fine ceramic thin films that have a thickness of up to approximately 1 µm and are deposited on

a silicon wafer, glass, organic polymer film or other such substrate or base. Provided that the test

specimens can be fitted on a wear testing apparatus as described in this document, the test specimen

dimensions and shape are of no concern. However, the thickness in the area where the wear formation

is performed shall be uniform.
5 Measurement principle

The wear properties of ceramic thin films are greatly affected by environmental humidity and the

humidity history of the thin film. Consequently, the wear resistance of a thin film test specimen should

be evaluated accurately by measuring wear of the thin film test specimen in dry and high-humidity

environments.

A reciprocating wear formation method or a rotating disc wear formation method shall be used as the

method for evaluating wear. Details of the principles pertaining to a reciprocating wear test method

are given in EN 1071:12. Details of the principles pertaining to a rotating disc wear test method are

given in ISO 20808 and EN 1071:13.

This document addresses both methods, i.e. a reciprocating wear test method and a rotating disc wear

test method. Annex A provides an example of results from testing carried out using a reciprocating

wear test method and a rotating disc wear test method.
6 Testing room environment

Measurements shall be carried out in a location subject to minimal changes in temperature and

humidity. Specifically, testing shall be carried out under the following environmental conditions:

a) testing room temperature: (23 ± 2) °C;
b) testing room relative humidity: 70 % or lower.
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ISO/FDIS 23737:2021(E)

NOTE If the temperature of the testing room is low, condensation can form on the wear evaluation apparatus.

7 Wear formation test apparatus

7.1 Reciprocating wear tester: The reciprocating wear tester shall consist of a test specimen

holder which retains a thin film test specimen, a drive apparatus which moves a thin film test specimen

reciprocally, a holder which retains and secures an indenter ball, a loading mechanism which applies a

constant load to the indenter ball, an equipment unit for detecting frictional force and a test environment

control sealing mechanism. Figure 1 shows a schematic of a test specimen holding system for a

reciprocating wear tester. Details concerning the reciprocal wear tester are given in EN 1071:12.

Key
1 indenter with a lateral force measurement system
2 test specimen
3 test specimen holder
4 wear track

Figure 1 — Schematic of a reciprocating wear tester (indicating the test specimen holding

system)

a) The test specimen holder shall move reciprocally within a horizontal plane and the deflection in

the direction of reciprocal motion shall be adjustable to 0,02 mm or less.

b) The drive apparatus shall allow for the setting of a predetermined sliding speed and changes in

the sliding speed due to variations in the frictional force shall be negligible. A reciprocating sliding

motion counter or equivalent device shall be included.

c) The indenter ball holder shall secure the indenter ball reliably against displacement by the frictional

force generated at the area of contact between the indenter ball and the test specimen, and shall

have high rigidity against induced stress.

d) The indenter ball loading mechanism shall apply and maintain a predetermined load either directly

or through a lever, and by means of a weight or a hydraulic or pressurized air system.

e) The frictional force detection equipment can be a load cell or a leaf spring strain measurement,

rotational torque measurement or other such measurement mechanism as desired, but its insertion

shall not affect the frictional conditions. The measurement precision for the frictional force shall

be within 1 % of the applied load. Use of an in situ linear wear measurement apparatus shall be

optional. If used, the apparatus shall have a depth resolution of less than 0,01 µm.

f) A sealing mechanism for controlling the test atmosphere shall be provided.

7.2 Rotating disc wear tester: The rotating disc wear tester shall consist of a test specimen holder

which retains a thin film test specimen, a drive apparatus which moves a thin film test specimen

rotationally, a holder which retains and secures an indenter ball, a loading mechanism which applies a

constant load to a thin film test specimen, a frictional force detection mechanism and a test environment

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ISO/FDIS 23737:2021(E)

control sealing mechanism. Figure 2 shows a schematic of a test specimen holding system for a rotating

disc wear tester. Details concerning the rotating disc wear tester are given in ISO 20808.

Key
1 indenter with a lateral force measurement system
2 test specimen
3 test specimen holder
4 wear track

Figure 2 — Schematic of a rotating disk wear tester (indicating the test specimen holding

system)

a) The rotating disc holder shall rotate within a horizontal or vertical plane, the deflection of the

rotational axis shall be adjustable to 0,02 mm or less, and the deflection in the direction of the

rotational axis at the area of contact shall be adjustable to 0,05 mm or less.

b) The drive apparatus shall allow for the setting of a disc rotation speed that provides a predetermined

sliding speed, and changes in the rotational speed due to variations in the frictional force shall be

negligible. A rotational speed counter or equivalent device shall be included.

c) The indenter ball holder shall secure the indenter ball reliably against rotation or displacement

by the frictional force generated at the area of contact between the indenter ball and the disc test

specimen, and shall have high rigidity against induced stress.

d) The indenter ball loading mechanism shall apply and maintain a predetermined load either directly

or through a lever, and by means of a weight or a hydraulic or pressurized air system.

e) The frictional force detection mechanism can be a load cell or a leaf spring strain measurement,

rotational torque measurement, or other such measurement mechanism as desired, but its

insertion shall not affect the frictional conditions. The measurement precision for the frictional

force shall be within 1 % of the applied load. Use of an in situ linear wear measurement apparatus

shall be optional. If used, the apparatus shall have a depth resolution of less than 0,01 µm.

f) A sealing mechanism for controlling the testing environment shall be provided.

7.3 Thermo-hygrostat chamber: The item used shall allow for the setting of relative humidity within

the range of 30 % to 90 % at a temperature of 23 °C. A metal or plastic tube shall be used to introduce air

of a predetermined temperature and humidity into the wear test chamber.

7.4 Dew point meter: The item shall be a capacitance (impedance) hygrometer (dew point meter) or

a chilled mirror dew point meter. Details are given in JIS Z 8806.

7.5 Stylus profilometer: A stylus surface roughness measurement apparatus as specified in

ISO 13565-1 and ISO 13565-2 or one with an equivalent or better precision shall be used.

7.6 Laser interferometric profilometer: The apparatus used shall make use of interference in parallel

light beams with an aligned wave surface to measure the surface profile of a test specimen surface, based

on the interference produced by a phase difference between light reflected from the test piece surface

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ISO/FDIS 23737:2021(E)

and light reflected from a reference surface serving as a standard. The apparatus used shall have a height

measurement resolution of approximately 10 nm at a magnification power of approximately 100× to

500×. A coherence scanning interferometry (CSI) system for three-dimensional mapping of surface

height is specified in ISO 25178-604.

7.7 Optical microscope: This apparatus shall magnify an object visually for observation using optical

lenses. The apparatus used shall have sufficient resolution at a magnification power of approximately

100× to 800×.

7.8 Scanning electron microscope: This microscope shall be equipped with a basic function for

forming a magnified image using an appropriate method, e.g. secondary electrons obtained from a test

specimen by two-dimensional scanning during irradiation of a test specimen with a tightly focused

electron beam. The apparatus used shall have sufficient resolution at an observational magnification

power of the order of 5 000×. For ceramic thin films, applying an electroconductive coating prior to the

observation is strongly recommended.

7.9 Energy dispersive X-ray spectroscopy: This instrument shall be equipped with an energy

dispersive X-ray (EDX) spectrometer to provide elemental identification by measuring the energy

of X-rays emitted from a specimen due to excitation by the primary electron beam. An elemental

distribution map can be acquired by combining the EDX signal with the position signal of the scanning

primary electron beam.

7.10 Drying chamber: Provided that the chamber can maintain an internal pressure of 4 kPa or lower

and a temperature of 130 °C or higher, its material, form and other details are not of concern.

7.11 Exhauster: A diaphragm pump or similar item shall be used. Provided that the item has an ultimate

pressure of 4 kPa or lower, its type shall not be of concern.
8 T
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