EN ISO 4491-2:1999

SLOVENSKI STANDARD
01-december-2000
Metallic powders - Determination of oxygen content by reduction methods - Part 2:
Loss of mass on hydrogen reduction (hydrogen loss) (ISO 4491-2:1997)
Metallic powders - Determination of oxygen content by reduction methods - Part 2: Loss
of mass on hydrogen reduction (hydrogen loss) (ISO 4491-2:1997)
Metallpulver - Bestimmung des Sauerstoffanteils durch Reduktionsverfahren - Teil 2:
Massenverlust durch Reduktion mit Wasserstoff (ISO 4491-2:1997)
Poudres métalliques - Dosage de l'oxygene par les méthodes de réduction - Partie 2:
Perte de masse par réduction dans l'hydrogene (perte dans l'hydrogene) (ISO 4491-
2:1997)
Ta slovenski standard je istoveten z: EN ISO 4491-2:1999
ICS:
77.160 Metalurgija prahov Powder metallurgy
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL IS0
STANDARD 4491-2
Second edition
1997-04-01
Metallic powders - Determination of
oxygen content by reduction methods -
Part 2:
Loss of mass on hydrogen reduction
(hydrogen loss)
Poudres m&alliques - Dosage de I’oxyg&ne par /es m&hodes de
kduction -
Partie 2: Perfe de masse par rkduction dans I’hydrogkne (perte dans
I’hydrogene)
Reference number
IS0 4491-2: 1997(E)
ISO 4491-2:1997(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing international Standards is normally carried out through IS0
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. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 4491-2 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 (IS0 449102:1989),
table 1 and clause 7 of which have been technically revised.
IS0 4491 consists of the following parts, under the general title Metallic
Determination of oxygen content by reduction methods:
powders -
- Part 1: General guidelines
- Part 2: Loss of mass on hydrogen reduction (hydrogen loss)
- Part 3: Hydrogen-reducible oxygen
- Parf 4: Total oxygen by reduction-extraction
Annex A forms an integral part of this part of IS0 4491.
0 IS0 1997
All rights resewed. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Internet central @ iso.ch
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Printed in Switzerland
II
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IS0 4491-2: 1997(E)
INTERNATIONAL STANDARD @ IS0
Determination of oxygen content
Metallic powders -
by reduction methods -
Part 2:
Loss of mass on hydrogen reduction (hydrogen loss)
1 Scope
This part of IS0 4491 specifies a method for the determination of the relative loss of mass which a metallic powder
undergoes when heated in a stream of pure dry hydrogen under specified conditions.
The purpose of this test is to evaluate a chemical powder characteristic which is of importance to the powder
metallurgical industry. The test is not intended as a means for the determination of the content of specific elements.
(See annex A and IS0 4491-l .)
The test method is applicable to unalloyed, partially alloyed and completely alloyed powders of the metals listed in
table 1 (see 6.1). It is not applicable to lubricated powders or to mixtures of metal powders.
The results can be influenced by the presence of reducible, oxidizable or volatile metals, metalloids or compounds (see
annex A). The results obtained on such powders shall be used with caution and their interpretation shall be subject to
agreement between supplier and user.
This part of IS0 4491 shall be read in conjunction with IS0 4491-I.
2 Normative reference
The following standard contains provisions which, through reference in this text, constitute provisions of this part of
IS0 4491. At the time of publication, the edition indicated was valid. All standards are subject to revision, and
parties to agreements based on this part of IS0 4491 are encouraged to investigate the possibility of applying the
most recent edition of the standard indicated below. Members of IEC and IS0 maintain registers of currently valid
International Standards.
Determination of oxygen content by reduction methods - Part I: General
IS0 4491-I :I 989, Metallic powders -
guidelines.
3 Reagents and materials
3.1 Hydrogen, with a maximum oxygen content of 0,005 % (m/m) and a dew point not higher than - 45 OC.
3.2 Nitrogen or argon, with a maximum oxygen content of 0,005 % (m/m) and a dew point not higher than - 45 OC.
(See also 6.3, third paragraph.)

IS0 4491=2:1997(E) @ IS0
4 Apparatus
An example of suitable test arrangement is shown schematically in figure 1.
4.1 Laboratory balance, of sufficient capacity, and capable of weighing to an accuracy of 0,l mg.
4.2 Electrically heated tubular furnace, that can be continuously operated at the appropriate temperatures
given in table 1 and that has a control system capable of maintaining the temperature in that part of the tube
containing the boat (4.5) to within the temperature tolerance stated in table I’.
NOTE - When testing magnetic powders, it is recommended that wire-wound furnaces shall be wound non-inductively.
4.3 Gas-tight tube, of quartz or refractory material (for example dense alumina). The inside diameter of the tube
shall be between 25 mm and 40 mm and its length such that it extends about 200 mm beyond each end of the
furnace.
When a large number of hydrogen loss determinations is to be carried out, a larger furnace than that described in
this part of IS0 4491, and one which permits several test portions to be tested simultaneously, may be used,
provided that the temperature and time conditions shown in table 1 are fulfilled and the results obtained are in
agreement with those obtained when the test is carried out with the preferred apparatus.
4.4 Totally enclosed thermocouple, for example platinum/platinum-rhodium, and an indicating or record ing
temperature with an accuracy of 5 OC.
instrument, permitting the measurement of
If for some reason it is desirable to place the thermocouple outside the reduction tube, this is acceptable. But in this
case, a preliminary calibration shall be made with a second thermocouple placed inside the tube in order to
ascertain that the temperature of the test sample is in accordance with the values and tolerances specified in
table 1.
4.5 Boat, preferably of high-alumina ceramic with a polished surface. Other materials, for example quartz and
nickel, may be used when test co
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