EN ISO 10070:2019

SLOVENSKI STANDARD
01-marec-2020
Kovinski prah - Ugotavljanje specifične ovojne površine z merjenjem zračne
prepustnosti nasute plasti prašnih delcev pri ustaljenem toku zraka skoznjo (ISO
10070:2019)
Metallic powders - Determination of envelope-specific surface area from measurements
of the permeability to air of a powder bed under steady-state flow conditions (ISO
10070:2019)
Metallpulver - Ermittlung der spezifischen Außenoberfläche durch Messung der
Luftdurchlässigkeit einer Pulverprobe unter gleichförmigen Strömungsbedingungen (ISO
10070:2019)
Poudres métalliques - Détermination de la surface spécifique d'enveloppe à partir de
mesures de la perméabilité à l'air d'un lit de poudre dans des conditions d'écoulement
permanent (ISO 10070:2019)
Ta slovenski standard je istoveten z: EN ISO 10070:2019
ICS:
77.160 Metalurgija prahov Powder metallurgy
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 10070
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2019
EUROPÄISCHE NORM
ICS 77.160
English Version
Metallic powders - Determination of envelope-specific
surface area from measurements of the permeability to air
of a powder bed under steady-state flow conditions (ISO
10070:2019)
Poudres métalliques - Détermination de la surface Metallpulver - Bestimmung der spezifischen
spécifique d'enveloppe à partir de mesures de la Außenoberfläche durch Messung der Permeabilität von
perméabilité à l'air d'un lit de poudre dans des Luft in einem Pulverbett unter gleichförmigen
conditions d'écoulement permanent (ISO 10070:2019) Strömungsbedingungen (ISO 10070:2019)
This European Standard was approved by CEN on 14 December 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 10070:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 10070:2019) has been prepared by Technical Committee ISO/TC 119 "Powder
metallurgy" in collaboration with Technical Committee CEN/SS M11 “Powder metallurgy” the
secretariat of which is held by CCMC.
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 June 2020, and conflicting national standards shall be
withdrawn at the latest by June 2020.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 10070:2019 has been approved by CEN as EN ISO 10070:2019 without any modification.

INTERNATIONAL ISO
STANDARD 10070
Second edition
2019-12
Metallic powders — Determination of
envelope-specific surface area from
measurements of the permeability to
air of a powder bed under steady-state
flow conditions
Poudres métalliques — Détermination de la surface spécifique
d'enveloppe à partir de mesures de la perméabilité à l'air d'un lit de
poudre dans des conditions d'écoulement permanent
Reference number
ISO 10070:2019(E)
©
ISO 2019
ISO 10070:2019(E)
© 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.
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Email: copyright@iso.org
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Published in Switzerland
ii © ISO 2019 – All rights reserved

ISO 10070:2019(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 3
5 General principles . 4
5.1 Permeability . 4
5.2 Carman-Arnell and Kozeny-Carman formulae . 4
5.3 General . 5
5.4 Envelope density . 5
6 Procedure. 6
6.1 Preparation of test portion . 6
6.2 Preparation of packed powder bed . 6
6.3 Determination . 6
7 Expression of results . 6
8 Test report . 7
Annex A (informative) Examples of methods of determining the permeability to air of a
powder bed . 8
Annex B (informative) Preliminary treatment of powder for de-agglomeration .17
Bibliography .18
ISO 10070:2019(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 119, Powder metallurgy, Subcommittee
SC 2, Sampling and testing methods for powders (including powders for hardmetals).
This second edition cancels and replaces the first edition (ISO 10070:1991), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— introduction of an automated test device based on the Gooden and Smith method, including
procedure and calibration.
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

ISO 10070:2019(E)
Introduction
The measurement of the permeability of a packed powder bed to a laminar gas flow is the basis of this
document. The determination can be made either at constant pressure drop (steady-state flow) or at
variable pressure drop (constant volume). This document deals only with determinations made under
steady-state flow conditions.
The permeability measured is influenced by the porosity of the powder bed. For a given particle shape,
the values of permeability and porosity can be used to calculate a specific surface area of the powder by
means of different formulae.
The surface area so calculated includes only those walls of the pores in the powder bed which are swept
by the gas flow. It does not take into account closed or blind pores. It is known as the envelope-specific
surface area. It can be very different from the total surface area of particles as measured, for instance,
by gas adsorption methods.
A single equation is used in the standard methods described in this document. It entails certain
limitations with respect to the type of powder (particle shape) and the porosity of the powder bed for
which the method is applicable. Consequently, this is not an absolute method, and the value obtained
depends upon the procedure used and the assumptions made.
The specific surface area determined can be converted into a mean equivalent spherical diameter (see
Clause 3).
INTERNATIONAL STANDARD ISO 10070:2019(E)
Metallic powders — Determination of envelope-specific
surface area from measurements of the permeability to air
of a powder bed under steady-state flow conditions
1 Scope
This document specifies a method of measuring the air permeability and the porosity of a packed
bed of metal powder, and of deriving therefrom the value of the envelope-specific surface area. The
permeability is determined under steady-state flow conditions, using a laminar flow of air at a pressure
near atmospheric. This document does not include the measurement of permeability by a constant
volume method.
Several different methods have been proposed for this determination, and several test devices are
available commercially. They give similar, reproducible results, provided that the general instructions
given in this document are respected, and the test parameters are identical.
This document does not specify a particular commercial test device and corresponding test procedure.
However, for the convenience of the user, an informative annex has been included (see Annex A) which
is intended to give some practical information on three specific methods:
— the Lea and Nurse method, involving a test device which can be built in a laboratory (see A.1);
— the Zhang Ruifu method, using a similar test device (see A.2);
— the Gooden and Smith method, involving a test device which can be built in a laboratory but for
which a commercial test device also exists. (Two types of commercial test device exist; one of these
is no longer available for purchase, but is still being used, see A.3.)
These methods are given as examples only. Other test devices available in various countries are
acceptable within the scope of this document.
This testing method is applicable to all metallic powders, including powders for hardmetals, up to
1 000 µm in diameter, but it is generally used for particles having diameters between 0,2 µm and
75,0 µm. It is not intended to be used for powders composed of particles whose shape is far from
equiaxial, i.e. flakes or fibres, unless specifically agreed upon between the parties concerned.
This testing method is not applicable to mixtures of different metallic powders or powders containing
binders or lubricant.
If the powder contains agglomerates, the measured surface area can be affected by the degree of
agglomeration. If the powder is subjected to a de-agglomeration treatment (see Annex B), the method
used is to be agreed upon between the parties concerned.
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 3954, Powders for powder metallurgical purposes — Sampling
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO 10070:2019(E)
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
envelope density
mass of a powder bed divided by its envelope volume (3.3)
Note 1 to entry: The envelope density may be less than the solid density when particles contain pores that do not
contribute to the gas flow through the powder bed.
3.2
envelope-specific surface area
specific surface area of a powder as determined by gas permeametry
3.3
envelope volume
volume occupied by the particles in a powder bed, excluding the volume of the interstices (3.5)
Note 1 to entry: In permeametry, the envelope volume comprises the volume of the solid matter plus the volume
of all the pores which do not contribute to gas flow (closed pores, blind pores, micropores, surface micropores,
surface roughness, etc.). Since this volume cannot be measured by any known method, it is taken, for the purposes
of this document, as being equal to the effective volume, as determined by pyknometry.
3.4
equivalent sphere diameter
diameter of theoretical non-porous spherical particles of identical size, with which the same method
of permeametry as that used for the powder under examination would give the same volume-specific
surface area (3.9)
3.5
interstices
spaces between particles in a powder bed, through which the air flows
3.6
mass-specific surface area
surface area of a powder divided by its mass
Note 1 to entry: This area depends on the type of method used for its determination.
3.7
permeability
ability of a porous material to allow a fluid to flow through it
Note 1 to entry: to entry In this document, the fluid used is dry air.
3.8
permeable porosity
volume of interstices (3.5) divided by the volume of the powder bed
3.9
volume-specific surface area
surface area of a powder divided by its effective volume (i.e. by its envelope volume)
2 © ISO 2019 – All rights reserved

ISO 10070:2019(E)
4 Symbols
Table 1 — Symbols used in the text
Symbol Meaning Unit Observations
Powder bed
A Cross-sectional area m Area of whole cross-section of
powder bed perpendicular to
flow direction:
πd
A=
d Diameter of measuring cell m
L Thickness (or height) m
m Mass of powder kg
ϱ Envelope density kg/m
e
ϱ Solid density kg/m
ɛ Permeable porosity
m
p
ε =−1
p
AL
e
ɛ Total porosity
m
ε= 1−
AL
Gas flow
q Volume flow rate m /s Converted to standard conditions
(STP - 0 °C, 1 atm)
p Mean gas pressure N/m
Δp Pressure drop N/m
η Viscosity of gas Ns/m
T Temperature of gas K
M Molar mass of gas kg/mol M = 0,029 kg/mol for air
R Molar gas constant
J J
R=83, 1
molK molK
Calculation
K Kozeny-Carman factor For the purposes of this document,
K = 5,0
δK Compound constant For the purposes of this document,
the generally accepted value of
2,25 is used
S Mass-specific surface area m /kg
w
−1
S Kozeny term m Formula (3)
K
−1
S Slip flow term m Formula (4)
m
−1
S Volume-specific surface area m
SS=
V
Ve w
Φ Permeability m
D Equivalent sphere diameter m
D==
SS
Vwe
ISO 10070:2019(E)
5 General principles
5.1 Permeability
Basically, permeametry is the experimental determination of the permeability, Φ, of a powder bed, the
porosity of which is known.
The permeability is determined by measuring the volume flow rate, q, and the drop-in pressure, Δp, of a
dry gas (generally air) continuously traversing the powder bed under laminar flow conditions.
The permeability is then calculated from Darcy's law, as shown in Formula (1):
qLη
Φ= (1)
ApΔ
5.2 Carman-Arnell and Kozeny-Carman formulae
The Carman-Arnell formula, as shown in Formula (2), relates specific surface area to the porosity and
permeability of a packed bed of powder and takes into account both the viscous flow and the slip flow.
This formula can be written as:
 
ε ε δηK ε
pp 8 2RT 0 p
 
Φ = +× (2)
 
Kη 3 πM
2 pS 1−ε
()
S 1−ε
Vp
()
 
Vp
 
The solution of Formula (2), which is quadratic in S , can be simplified by calculating the value of two
V
terms, the Kozeny term S and the slip flow term S , and then combining them to give S .
K m V
The Kozeny term S is given by Formula (3):
K
ApΔ ε
p
S = (3)
K
KL1−εηq
()
p
The Kozeny term is identical to the Kozeny-Carman formula for S and gives the contribution to the
V
surface area of the powder due to streamline flow.
The slip flow term S is given by Formula (4)
m
δεK
ApΔ 8 2RT
0 p
S =× × (4)
m
KLq 3 πM
p 1−ε
()
p
or, in the case of air, Formula (5):
1−εη
()
p
SS=×81 T (5)
mK
pε
p
S is then given by Formula (6):
v
SS
mm
S =+ +S (6)
V K
4 © ISO 2019 – All rights reserved

ISO 10070:2019(E)
and the mass-specific surface area S by Formula (7):
w
S
V
S = (7)
w

e
The equivalent sphere diameter D is given by Formula (8):
D== (8)
SS
Ve w
The Carman-Arnell formula, Formula (2), shall be used when the volume-specific surface area is greater
6 −1
than 10 m (mean particle size less than 6 µm), because the slip flow component of the permeability
becomes significant in addition to the viscous flow term.
For coarser powders, the Kozeny-Carman formula, Formula (3), may be used by agreement between the
parties concerned; the error introduced by neglecting slip flow is about 10 % at a mean particle size of
6 µm and increases as the powder becom
...