Fine ceramics (advanced ceramics, advanced technical ceramics) — Determination of densification properties of ceramic powders on natural sintering

This document specifies the test method to determine the extent to which ceramic powder compacts made of granulated or ungranulated ceramic powders are densified, when they are sintered at a high temperature without the application of any external pressure or external densification force. The test method is applicable to pure oxides, mixtures of oxides and solid solutions, and is also applicable to non-oxides (e.g. carbides, nitrides) that can be sintered under vacuum or constant gas pressure (1 bar or less) to prevent oxidation or decomposition. The test method is not applicable to ceramics that can only be sintered using pressure-assisted sintering techniques such as hot pressing (HP), hot isostatic pressing (HIP), gas pressure sintering (GPS) or spark plasma sintering (SPS). Inorganic sintering additives can be used where their presence is reported.

Céramiques techniques (céramiques avancées, céramiques techniques avancées) — Détermination des propriétés de densification des poudres céramiques lors d’un frittage naturel

General Information

Status
Published
Publication Date
22-Oct-2019
Technical Committee
Drafting Committee
Current Stage
6060 - International Standard published
Start Date
23-Oct-2019
Completion Date
23-Oct-2019
Ref Project

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ISO 21821:2019(E)
Deleted: /FDIS
ISO TC 206/WG 2
Secretariat: JISC

Fine ceramics (advanced ceramics, advanced technical ceramics) — Determination of

densification properties of ceramic powders on natural sintering
Warning for WDs and CDs

This document is not an ISO International Standard. It is distributed for review and comment. It is

subject to change without notice and may not be referred to as an International Standard.

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 supporting documentation.
---------------------- Page: 1 ----------------------
ISO 21821:2019(E)
© ISO 2019, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or

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

or posting on the internet or an intranet, without prior written permission. Permission can be

requested from either ISO at the address below or ISO’s member body in the country of the

requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH‐1214 Vernier, Geneva, Switzerland
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2019 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 21821:2019(E)
Contents

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

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

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

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

4  Principle ............................................................................................................................................................. 1

5  Symbols and designation .............................................................................................................................. 2

6  Apparatus ........................................................................................................................................................... 3

7  Sampling ............................................................................................................................................................. 6

8  Procedure ........................................................................................................................................................... 6

8.1  Compaction ........................................................................................................................................................ 6

8.2  Heat treatment ................................................................................................................................................. 6

8.2.1  Selection of test temperatures .................................................................................................................... 6

8.2.2  Thermal cycle.................................................................................................................................................... 6

8.3  Measurement .................................................................................................................................................... 7

9  Expression of results ...................................................................................................................................... 7

9.1  Calculation ......................................................................................................................................................... 7

9.2  Densification curve ......................................................................................................................................... 8

10  Test report ......................................................................................................................................................... 9

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

© ISO 2019 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 21821:2019(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.
iv © ISO 2019 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 21821:2019(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Determination of densification properties of ceramic
powders on natural sintering
1 Scope

This document specifies the test method to determine the extent to which ceramic powder compacts

made of granulated or ungranulated ceramic powders are densified, when they are sintered at a high

temperature without the application of any external pressure or external densification force. The test

method is applicable to pure oxides, mixtures of oxides and solid solutions, and is also applicable to

non‐oxides (e.g. carbides, nitrides) that can be sintered under vacuum or constant gas pressure (1 bar

or less) to prevent oxidation or decomposition. The test method is not applicable to ceramics that can

only be sintered using pressure‐assisted sintering techniques such as hot pressing (HP), hot isostatic

pressing (HIP), gas pressure sintering (GPS) or spark plasma sintering (SPS). Inorganic sintering

additives can be used where their presence is reported.
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 3611, Geometrical product specifications (GPS) — Dimensional measuring equipment: Micrometers

for external measurements — Design and metrological characteristics

ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

ISO 17172, Fine ceramics (advanced ceramics, advanced technical ceramics) — Determination of

compaction properties of ceramic powders
3 Terms and definitions
No terms and definitions are listed in this document.

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

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

When ceramic powder compacts are heat‐treated at high temperatures, they shrink and are densified

due to sintering. The mass, dimensions (diameter and height), volume and apparent density of a

ceramic powder compact are measured before and after sintering through thermal treatment. The

variations in mass, dimensions, volume and apparent density depend on maximum temperature, dwell

time, heating rate and apparent density after compaction, and can be expressed as a function of these

parameters. For example, the variation in relative density can be plotted as a function of sintering

temperature for each compacting pressure.
© ISO 2019 – All rights reserved 1
---------------------- Page: 5 ----------------------
ISO 21821:2019(E)
5 Symbols and designation

Symbols used throughout this document and their designations are given in Table 1.

Table 1 — Symbols, designations and units of mass, volume, density, dimension and sintering

temperature
Symbol Designation Unit Formula
D Diameter of sample before sintering mm — Moved down [1]: Diameter of
sample after sintering
Deleted: ¶
D Diameter of sample after sintering mm —
Deleted: mm¶
Ha Height of sample before sintering mm —
Moved (insertion) [1]
H Height of sample after sintering mm —
Deleted: ¶
m Mass before sintering g —
m Mass after sintering g —
Moved down [2]: Height of
sample after sintering
V Volume before sintering cm —
Deleted: mm¶
V Volume after sintering cm —
Moved (insertion) [2]
T Sintering temperature °C —
Deleted: ¶
Relative diameter variation (shrinkage) at the end of sintering — (3)
Moved down [3]: Mass after
sintering
Deleted: g¶
Relative height variation (shrinkage) at the end of sintering — (4)
Moved (insertion) [3]
Deleted: ¶
Relative mass variation at the end of sintering — (5)
Moved down [4]: Volume after
sintering
Relative volume variation at the end of sintering — (6)
Deleted: cm¶
Moved (insertion) [4]
Relative density variation at the end of sintering — (7)
3 Deleted: ¶
ρ Apparent density before sintering g/cm (1)
ρ Apparent density after sintering g/cm (2) ρth
Moved down [5]: Apparent
ρ Theoretical density g/cm —
density after sinteringTheoretical
These characteristics are linked by relations in Formulae (1) to (7):
Moved down [6]: Theoretical
density
  (1)
Moved down [7]: g/cm
Moved down [8]: g/cm
Deleted: ¶
...

INTERNATIONAL ISO
STANDARD 21821
First edition
2019-10
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Determination of densification
properties of ceramic powders on
natural sintering
Céramiques techniques (céramiques avancées, céramiques techniques
avancées) — Détermination des propriétés de densification des
poudres céramiques lors d’un frittage naturel
Reference number
ISO 21821:2019(E)
ISO 2019
---------------------- Page: 1 ----------------------
ISO 21821:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 21821:2019(E)
Contents Page

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

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

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

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

4 Principle ........................................................................................................................................................................................................................ 1

5 Symbols and designation ............................................................................................................................................................................. 2

6 Apparatus ..................................................................................................................................................................................................................... 3

7 Sampling ........................................................................................................................................................................................................................ 6

8 Procedure..................................................................................................................................................................................................................... 6

8.1 Compaction ................................................................................................................................................................................................ 6

8.2 Heat treatment ........................................................................................................................................................................................ 6

8.2.1 Selection of test temperatures ............................................................................................................................. 6

8.2.2 Thermal cycle...................................................................................................................................................................... 6

8.3 Measurement ............................................................................................................................................................................................ 7

9 Expression of results ........................................................................................................................................................................................ 7

9.1 Calculation .................................................................................................................................................................................................. 7

9.2 Densification curve .............................................................................................................................................................................. 7

10 Test report ................................................................................................................................................................................................................... 9

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

© ISO 2019 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 21821:2019(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.
iv © ISO 2019 – All rights reserved
---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 21821:2019(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Determination of densification properties of
ceramic powders on natural sintering
1 Scope

This document specifies the test method to determine the extent to which ceramic powder compacts

made of granulated or ungranulated ceramic powders are densified, when they are sintered at a high

temperature without the application of any external pressure or external densification force. The test

method is applicable to pure oxides, mixtures of oxides and solid solutions, and is also applicable to

non-oxides (e.g. carbides, nitrides) that can be sintered under vacuum or constant gas pressure (1 bar

or less) to prevent oxidation or decomposition. The test method is not applicable to ceramics that can

only be sintered using pressure-assisted sintering techniques such as hot pressing (HP), hot isostatic

pressing (HIP), gas pressure sintering (GPS) or spark plasma sintering (SPS). Inorganic sintering

additives can be used where their presence is reported.
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 3611, Geometrical product specifications (GPS) — Dimensional measuring equipment: Micrometers for

external measurements — Design and metrological characteristics

ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

ISO 17172, Fine ceramics (advanced ceramics, advanced technical ceramics) — Determination of

compaction properties of ceramic powders
3 Terms and definitions
No terms and definitions are listed in this document.

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

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

When ceramic powder compacts are heat-treated at high temperatures, they shrink and are densified

due to sintering. The mass, dimensions (diameter and height), volume and apparent density of a ceramic

powder compact are measured before and after sintering through thermal treatment. The variations in

mass, dimensions, volume and apparent density depend on maximum temperature, dwell time, heating

rate and apparent density after compaction, and can be expressed as a function of these parameters.

For example, the variation in relative density can be plotted as a function of sintering temperature for

each compacting pressure.
© ISO 2019 – All rights reserved 1
---------------------- Page: 5 ----------------------
ISO 21821:2019(E)
5 Symbols and designation

Symbols used throughout this document and their designations are given in Table 1.

Table 1 — Symbols, designations and units of mass, volume, density, dimension and sintering

temperature
Symbol Designation Unit Formula
D Diameter of sample before sintering mm —
D Diameter of sample after sintering mm —
H Height of sample before sintering mm —
H Height of sample after sintering mm —
m Mass before sintering g —
m Mass after sintering g —
V Volume before sintering cm —
V Volume after sintering cm —
T Sintering temperature °C —
Relative diameter variation (shrinkage) at the end of sintering — (3)
Relative height variation (shrinkage) at the end of sintering — (4)
Relative mass variation at the end of sintering — (5)
Relative volume variation at the end of sintering — (6)
Relative density variation at the end of sintering — (7)
ρ Apparent density before sintering g/cm (1)
ρ Apparent density after si
...

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