BRITISH STANDARD

Advanced technical
ceramics Ð
Methods of test for ceramic
powders
Part 10. Determination of compaction
properties

The European Standard EN 725-10 : 1997 has the status of a
British Standard

ICS 81.060.99

NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW

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BS EN
725-10 : 1997


BS EN 725-10 : 1997


Committees responsible for this
British Standard
The preparation of this British Standard was entrusted to Technical Committee
RPI/13, Advanced technical ceramics, upon which the following bodies were
represented:
AEA Technology
Aluminium Federation
British Ceramic Research Ltd.
British Industrial Ceramic Manufacturers' Association
Department of Trade and Industry (National Physical Laboratory)
Flat Glass Manufacturers' Association
GAMBICA (BEAMA Ltd.)
Institute of Refractories Engineers
Ministry of Defence
Refractories Association of Great Britain
Society of British Aerospace Companies Ltd.
University of Manchester

This British Standard, having
been prepared under the
direction of the Sector Board for
Materials and Chemicals, was
published under the authority of
the Standards Board and comes
into effect on
15 July 1997
 BSI 1997

Amendments issued since publication

Amd. No.

The following BSI references
relate to the work on this
standard:
Committee reference RPI/13
Draft for comment 93/301336 DC
ISBN 0 580 27913 8

Date

Text affected


BS EN 725-10 : 1997

Contents

Committees responsible
National foreword
Foreword
Text of EN 725-10

 BSI 1997

Page
Inside front cover
ii
2
3


i


BS EN 725-10 : 1997

National foreword
This British Standard has been prepared by Technical Committee RPI/13 and is the
English language version of EN 725-10 : 1997 Advanced technical ceramics Ð Methods
of test for ceramic powders Ð Part 10: Determination of compaction properties,
published by the European Committee for Standardization (CEN).
EN 725-10 : 1997 was produced as a result of international discussions in which the
United Kingdom took an active part.
EN 725-10 : 1997 has been approved by CEN member bodies under the weighted voting
procedures introduced in 1988 to coincide with the introduction of `New Approach'
Directives from the Commisssion of the European Community.
NOTE. International and European Standards as well as overseas standards, are available from Customer
Services, BSI, 389 Chiswick High Road, London, W4 4AL.

Compliance with a British Standard does not of itself confer immunity
from legal obligations.

Summary of pages
This document comprises a front cover, an inside front cover, pages i and ii, the EN
title page, pages 2 to 8, an inside back cover and a back cover.

ii

 BSI 1997



EN 725-10

EUROPEAN STANDARD
NORME EUROPÊENNE
EUROPẰISCHE NORM

March 1997

ICS 81.060.99
Descriptors: Ceramics, powdery materials, compression tests, compacting, determination, compressibility, testing conditions

English version

Advanced technical ceramics Ð Methods of test for ceramic
powders Ð Part 10: Determination of compaction properties

CeÂramiques techniques avanceÂes Ð MeÂthodes
d'essai pour poudres ceÂramiques Ð Partie 10:
DeÂtermination des proprieÂteÂs de compaction

Hochleistungskeramik Ð PruÈfverfahren fuÈr
keramische Pulver Ð Teil 10: Bestimmung der
Verdichtungseigenschaften

This European Standard was approved by CEN on 1996-12-22. 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 Central Secretariat 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 Central Secretariat has the
same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Denmark,
Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands,
Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.

CEN
European Committee for Standardization
Comite EuropeÂen de Normalisation
EuropaÈisches Komitee fuÈr Normung
Central Secretariat: rue de Stassart 36, B-1050 Brussels
1997 Copyright reserved to CEN members
Ref. No. EN 725-10 : 1997 E


Page 2
EN 725-10 : 1997

Foreword
This European Standard has been prepared by
Technical Committee CEN/TC184, Advanced technical
ceramics, the secretariat of which is held by BSI.
This European Standard shall be given the status of a
national standard, either by publication of an identical
text or by endorsement, at the latest by
September 1997, and conflicting national standards
shall be withdrawn at the latest by September 1997.

EN 725 consists of 11 parts:
Part 1 :
Part 2 :

Determination of impurities in alumina
Determination of impurities in barium
titanate (ENV)
Part 3 : Determination of oxygen content of
non-oxides by thermal extraction
Part 4 : Determination of oxygen content of
non-oxides by XRF analysis (ENV)
Part 5 : Determination of particle size distribution
Part 6 : Determination of specific area
Part 7 : Determination of absolute density
Part 8 : Determination of tapped bulk density
Part 9 : Determination of untamped bulk density
Part 10 : Determination of compaction properties
Part 11 : Determination of reactivity on sintering
(ENV)

Contents
Foreword
1
Scope
2
Normative references
3
Principle
4
Symbols and designation

5
Apparatus
6
Procedure
7
Expression of results
8
Test report
9
Repeatability and reproducibility
Annex A (informative) Example of
presentation of test report

Page
2
3
3
3
3
3
3
4
5
7
8

According to the CEN/CENELEC Internal Regulations,
the national standards organizations of the following
countries are bound to implement this European
Standard: Austria, Belgium, Denmark, Finland, France,

Germany, Greece, Iceland, Ireland, Italy, Luxembourg,
Netherlands, Norway, Portugal, Spain, Sweden,
Switzerland and the United Kingdom.

 BSI 1997


Page 3
EN 725-10 : 1997

1 Scope

5 Apparatus

This part of EN 725 describes methods for the
determination of the extent to which a ceramic powder
is compacted, when subjected to uniaxial compressive
loading in a confining die, under specified conditions.

5.1 Die, which shall be made from hard material,
preferably tungsten carbide. The cylindrical die shall
contain two punches for producing cylindrical
compacts and shall be of the floating type or of the
type suspended from a spring. The die shall be capable
of making compacts of diameter 20 mm to 26 mm with
a height to diameter ratio between 0,3 and 0,5, with
tolerances as indicated in figure 1. The upper part of
the die shall be (preferably) designed to avoid damage
to the compact during the ejection phase due to
springback phenomenon. An ejection cone of

height 5 mm, allowing an increase of the diameter at
the top of the die of approximately 1 %, as shown in
figure 1, should be used.
The die may be fitted with a venting valve.

NOTE. An example of the reporting of results is shown in
annex A.

2 Normative references
This European Standard incorporates by dated or
undated reference, provisions from other publications.
These normative references are cited at the
appropriate places in the text and in the publications
listed hereafter. For dated references, subsequent
amendments to or revisions of any of these
publications apply to this European Standard only
when incorporated in it by amendment or revision. For
undated references the latest edition of the publication
referred to applies.
ISO 3611 Micrometer callipers for external
measurement

3 Principle
The powder is compacted uniaxially in a confining die
by double-action pressing. Samples of the powder may
be pressed either at a single specified pressure or at a
series of specified pressures. After ejection from the
die, the apparent density of the compact is determined.
The density obtained in the former case represents the
compaction properties of the powder at the specified

pressure. The densities obtained in the latter case are
utilized for drawing the compaction curve of the
powder, which is a plot of the density as a function of
the compacting pressure.

4 Symbols and designation
Table 1.
Symbol

Designation

Unit

ra

Apparent density kg/m3

m

Mass of the
compact

g

V

Volume of the
compact

cm3


If the apparent density is measured at one specified
pressure only, for example 200 MPa, the symbol
becomes ra (200).

 BSI 1997

5.2 Press, capable of applying sufficient force with an
accuracy of ± 2 %.
5.3 Balance, capable of weighing at least 10 g with an
accuracy of ± 0,005 g.
5.4 Micrometer, (see ISO 3611), or other suitable
measuring device for measuring the dimensions of the
compacts with an accuracy of ± 0,01 mm.

6 Procedure
6.1 Drying
NOTE. Powders containing organic additives should not be dried.

Dry the powder at 110 ÊC ± 5 ÊC for at least 24 h and
until constant mass is attained. Store in a desiccator
until the test is performed. During drying the powder
layer shall have a maximum thickness of 5 mm.

6.2 Quantity
The quantity of the test sample shall be chosen to give
the required number of compacts (see clause 8), with
dimensions as specified in 5.1. Three compacts shall
be used for each pressure used in the determination. If
necessary, preliminary tests should be made in order to

establish the quantity of powder which is needed for
fulfilling this requirement.
6.3 Cleaning of the die and punches
Wipe the die cavity and the punches with a soft, clean
paper towel soaked with an appropriate solvent such
as acetone. Allow the solvent to evaporate.


Page 4
EN 725-10 : 1997

6.4 Powder testing conditions
6.4.1 Powders which do not contain a lubricant shall
be compacted either:
a) in a dry die;
NOTE. Seizure and excessive die wear may occur, particularly
at high compacting pressures

b) in a die with lubricated walls (see 6.5);
c) in a dry die, after mixing a lubricant with the
powder (see 6.4.2).
6.4.2 Powders which contain a lubricant shall be
compacted in a dry die.
6.5 Lubrication
6.5.1 Lubrication of the die walls or of the powder is
likely to modify the compaction results. Similarly,
depending on the type and quantity of lubricant added
to the powder, the results may vary within wide
ranges. The test report (see clause 8) shall therefore
mention whether or not lubrication had taken place,

and if the lubrication was carried out on the walls of
the die or on the powder.
Use one of the following two methods (see 6.5.2
and 6.5.3) if lubrication is applied.
6.5.2 To lubricate the die wall, apply a mixture or a
solution of a lubricant in the volatile organic liquid, for
example 20 g of stearic acid in 980 g of acetone. After
any excess liquid has drained away, allow the solution
adhering to the walls to evaporate leaving a thin layer
of lubricant.
Alternatively, press in the die, before testing, inert
spheres (polyurethane spheres for instance) coated
with lubricant. After removal of the pressed disc of
inert material, a thin layer of lubricant remains on the
walls of the die.
6.5.3 Lubricate the powder to be tested by thoroughly
mixing it with a quantity (0,5 % to 1,5 %) of a suitable
solid lubricant (for example zinc stearate or stearic
acid).
6.6 Compacting and ejection
6.6.1 Position the die using spacers between the die
and the foot of the lower punch, in order to leave a
free volume in the die large enough to contain the bulk
powder (see figure 2).
6.6.2 A known weight of powder, which shall be the
same for each compact in a series, sufficient to almost
fill the die cavity is poured into the die.
6.6.3 Wipe the wall of the die remaining free, to
remove any powder that may have adhered to it during
the filling of the mould.


6.6.5 Position the die with its punches between the
plate ends of the press. Apply and release a
preliminary pressure. The pressure shall be lower than
the lower pressure used in the test. Remove the
spacers supporting the die. If the die is supported by
springs, or by some similar system, it is unnecessary to
apply this preliminary pressure.
Apply the selected test pressure and maintain
for 1 min.
NOTE.Taking into account the different press technology, it is
difficult to specify a rate of increase of the force as well as the
displacement speed of the punch.

6.6.6 Perform decompression slowly (for
example 10 mm/min) to avoid breaking the compact.
6.6.7 Eject the compact by using a relative movement
between the die and the lower punch. Transfer the
compact to a desiccator for 1 h to allow a possible
expansion due to springback. Remove from the
desiccator, weigh to the nearest 0,005 g and measure to
the nearest 0,01 mm, the dimensions (both height and
diameter) in three different places, and take the
average.
6.7 Compacting pressures
For plotting the compaction curve of a powder at
different pressures, the pressures applied shall
be 25 MPa, 50 MPa, 100 MPa and 200 MPa. If
compaction properties are to be determined at a single
pressure only, this pressure shall be one of the

pressures given above.

7 Expression of results
7.1 Calculation
The apparent density of the compact is given by the
formula:
m
ra =
V
where:
m
V

is the mass of the compact, in grams;
is the volume of the compact, in cubic
centimetres

Calculate the density in grams per cubic centimetre
and then convert the answer to kilograms per cubic
metre, expressed to the nearest 20 kg/m3.
Express the compaction properties for a given
compacting pressure as the average of the three
density figures, calculated to the nearest 20 kg/m3,
obtained at the specified pressure.

6.6.4 Insert the upper punch into the die.

 BSI 1997



Page 5
EN 725-10 : 1997

Figure A.1 Example of tooling to produce a cylindrical compact

 BSI 1997


Page 6
EN 725-10 : 1997

Figure A.2 Diagram of powder compacting operations

 BSI 1997


Page 7
EN 725-10 : 1997

7.2 Compaction curve
Draw the compaction curve of a powder through
points representing the average of determinations of ra
at each of the specified pressures.

8 Test report
The test report shall include the following information
(see example of presentation in annex A):
a) the name of the testing establishment;
b) date of the test, report identification and number,
operator, signatory;

c) a reference to this standard, i.e. determined in
accordance with EN 725-10;
d) a description of the powder (material
manufacturer, batch or code number);
e) the dimensions of the compacts;
f) the type, nature and amount of lubricant and any
other organic additives used in the test, including:
± lubrication of the die walls, or no lubrication;
± lubrication of the powder, or no lubrication
(state how the lubricant has been added);
± other organic additives;
g) the compacting pressures;
h) the result obtained including the compaction
curve;
i) comments about the test or test results.

9 Repeatability and reproducibility
The experience of three laboratories indicates that the
method is capable, for an alumina powder of apparent
density 2 140 kg/m3 (lubricated with 1 % to 1,5 % zinc
stearate or stearic acid and pressed in a non-lubricated
mould), of achieving:
a) a standard deviation of repeatability of 6 kg/m3 ;
b) a standard deviation of reproducibility of 4 kg/m3.

 BSI 1997


Page 8
EN 725-10 : 1997


Annex A (informative)
Example of presentation of test report
Determination of the compaction properties of an
alumina powder.
A.1 Details of test house, and other requirements of
clause 8.
A.2 The compaction properties of an alumina powder
are determined according to EN 725-10.
A.3 This sample is an alumina powder.
Mass on receipt:
Dried for :
Mass loss :

75,9523 g
24 h in oven at 110 ÊC
89,3 mg (1176 ppm)

A.4 Test conditions
Lubrication
Lubrication of the powder by the addition of 1,5 %
stearic acid in powder form. Mix for 10 min.
Press
Sechmy single-acting 200 kN hydraulic press, equipped
with a floating spring cradle.
Compaction apparatus
Die (tungsten carbide) :
Upper punch (tungsten
carbide) :
Lower punch (tungsten

carbide) :

20,000 mm in diameter
19,993 mm in diameter
19,995 mm in diameter

Compaction procedure
Insertion of the powder according to the procedure.
Loading with uniform increase of load # 0,6 kN/s
achieved by progressive throttling of a needle valve for
return to the oil supply tank of the cylinder.
Holding for 60 s at the nominal compacting pressure
(25, 50, 100, 150, or 200 MPa).
Slow decompression, according to a cycle identical to
the one used for loading.
Ejection.
Determination of the density of the compacts.
Weighing of compact (Type of balance).
Measurement of diameter (Type of micrometer) e.g., on
base with sliding mobile key 6 mm in diameter.
Measurement of height (same instrument).
Calculation of density.

 BSI 1997


blank


BSI

389 Chiswick High Road
London
W4 4AL

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