Steels — Determination of total silicon contents — Reduced molybdosilicate spectrophotometric method — Part 2: Silicon contents between 0,01 % and 0,05 %

ISO 4829-2:2016 specifies a spectrophotometric method for the determination of total silicon in steels using reduced molybdosilicate. The method is applicable to silicon contents between 0,01 % and 0,05 % (mass fraction) in steels.

Aciers — Détermination du silicium total — Méthode spectrophotométrique au silicomolybdate réduit — Partie 2: Teneurs en silicium comprises entre 0,01 % et 0,05 %

ISO 4829-2:2016 spécifie une méthode spectrophotométrique au silicomolybdate réduit pour la détermination du silicium total dans les aciers. La méthode est applicable aux teneurs en silicium comprises entre 0,01 % et 0,05 % (fraction massique) dans les aciers.

General Information

Status
Published
Publication Date
11-Feb-2016
Current Stage
9093 - International Standard confirmed
Start Date
16-Aug-2021
Completion Date
16-Aug-2021
Ref Project

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INTERNATIONAL ISO
STANDARD 4829-2
Second edition
2016-02-15
Steels — Determination of total silicon
contents — Reduced molybdosilicate
spectrophotometric method —
Part 2:
Silicon contents between 0,01 % and
0,05 %
Aciers — Détermination du silicium total — Méthode
spectrophotométrique au silicomolybdate réduit —
Partie 2: Teneurs en silicium comprises entre 0,01 % et 0,05 %
Reference number
ISO 4829-2:2016(E)
ISO 2016
---------------------- Page: 1 ----------------------
ISO 4829-2:2016(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, 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 2016 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 4829-2:2016(E)
Contents Page

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

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

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

3 Principle ........................................................................................................................................................................................................................ 1

4 Reagents ........................................................................................................................................................................................................................ 1

5 Apparatus ..................................................................................................................................................................................................................... 3

6 Sampling ........................................................................................................................................................................................................................ 4

7 Procedure..................................................................................................................................................................................................................... 4

7.1 Test portion ................................................................................................................................................................................................ 4

7.2 Blank test ..................................................................................................................................................................................................... 4

7.3 Determination ......................................................................................................................................................................................... 4

7.3.1 Dissolution of the test portion ............................................................................................................................. 4

7.3.2 Treatment of insoluble residue ........................................................................................................................... 4

7.3.3 Preparation of the test solution .......................................................................................................................... 4

7.3.4 Development of the colour ...................................................................................................................................... 5

7.3.5 Spectrophotometric measurements ............................................................................................................... 5

7.4 Establishment of the calibration curve .............................................................................................................................. 6

7.4.1 Preparation of the calibration solutions ...................................................................................................... 6

7.4.2 Spectrophotometric measurements ............................................................................................................... 6

7.4.3 Plotting of the calibration curve ......................................................................................................................... 6

8 Expression of results ........................................................................................................................................................................................ 6

8.1 Method of calculation ........................................................................................................................................................................ 6

8.2 Precision ....................................................................................................................................................................................................... 7

9 Test report ................................................................................................................................................................................................................... 7

Annex A (informative) Additional information on the interlaboratory test ...............................................................9

Bibliography .............................................................................................................................................................................................................................10

© ISO 2016 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 4829-2:2016(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 on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical

Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information.

The committee responsible for this document is ISO/TC 17, Steel, Subcommittee SC 1, Methods of

determination of chemical composition.

This second edition cancels and replaces the first edition (ISO 4829-2:1988), which has been

technically revised.

ISO 4829 consists of the following parts, under the general title Steels — Determination of total silicon

contents — Reduced molybdosilicate spectrophotometric method:
— Part 1: Silicon contents between 0,05 % and 1,0 %
— Part 2: Silicon contents between 0,01 % and 0,05 %
iv © ISO 2016 – All rights reserved
---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 4829-2:2016(E)
Steels — Determination of total silicon contents —
Reduced molybdosilicate spectrophotometric method —
Part 2:
Silicon contents between 0,01 % and 0,05 %
1 Scope

This part of ISO 4829 specifies a spectrophotometric method for the determination of total silicon in

steels using reduced molybdosilicate.

The method is applicable to silicon contents between 0,01 % and 0,05 % (mass fraction) in steels.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

ISO 648, Laboratory glassware — Single-volume pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 3696, Water for analytical laboratory use — Specification and test methods

ISO 14284, Steel and iron — Sampling and preparation of samples for the determination of chemical

composition
3 Principle
Dissolution of a test portion in a hydrochloric/nitric acids mixture.

Fusion of the acid-insoluble residue with sodium peroxide. Formation of the oxidized molybdosilicate

(yellow) complex in weak acid solution.

Selective reduction of the molybdosilicate complex to a blue complex with ascorbic acid, after increasing

the sulphuric acid concentration and adding oxalic acid to prevent the interference of phosphorus,

arsenic and vanadium.

Spectrophotometric measurement of the reduced blue complex at a wavelength of about 810 nm.

4 Reagents

During the analysis, unless otherwise specified, use only reagents of recognized analytical grade and

only grade 2 water as specified in ISO 3696. Water demineralized by ion-exchange shall not be used as

it may contain significant amounts of colloidal silica.

Reagents supplied in glass bottles, once opened, might absorb moisture and become reactive to

glassware. Alkaline reagents, e.g. sodium carbonate and sodium peroxide, are particularly susceptible.

To avoid the risk of significant contamination arising from this source, it is recommended that only

freshly opened bottles of all reagents be used for the preparation of reagent solutions.

© ISO 2016 – All rights reserved 1
---------------------- Page: 5 ----------------------
ISO 4829-2:2016(E)

To avoid adventitious contamination, the water shall be prepared, as required, for the specific purpose

and collected in polypropylene containers for immediate use.

All solutions shall be freshly prepared and stored in polypropylene or polytetrafluoroethylene containers.

4.1 Pure iron, silicon content less than 2 µg/g.
4.2 Sodium peroxide, particle size less than 500 µm.
4.3 Sulphuric acid, ρ approximately 1,84 g/ml, diluted 1 + 3.

Add cautiously, while stirring, 250 ml of sulphuric acid, ρ approximately 1,84 g/ml to 600 ml of water.

Cool, dilute to 1 l with water and mix.
4.4 Sulphuric acid, ρ approximately 1,84 g/ml, diluted 1 + 19.

Add cautiously, while stirring, 50 ml of sulphuric acid, ρ approximately 1,84 g/ml to 800 ml of water.

Cool, dilute to 1 l with water and mix.
4.5 Hydrochloric/nitric acids mixture.

Add 180 ml of hydrochloric acid, ρ approximately 1,19 g/ml and 65 ml of nitric acid, ρ approximately

1,40 g/ml, to 500 ml of water. Cool, dilute to 1 l with water and mix.
4.6 Ascorbic acid, 20 g/l solution.
This solution shall be freshly prepared.
4.7 Oxalic acid, 50 g/l solution.

Dissolve 5 g of oxalic acid di-hydrate (C H O ·2H O) in water, dilute to 100 ml with water and mix.

2 2 4 2
4.8 Hydrogen peroxide, 60 g/l solution.
Dilute 200 ml of hydrogen peroxide, 300 g/l, to 1 l with water and mix.
4.9 Potassium permanganate, 22,5 g/l solution.

This solution shall be filtered before use in order to remove the fine particles of MnO that may be

present in the solution, as they will interfere with the measurement.
4.10 Sodium molybdate, 25 g/l solution.

Dissolve 2,5 g of sodium molybdate di-hydrate (Na MoO ·2H O) in 50 ml of water and filter through a

2 4 2
medium-texture filter paper.

Immediately before use, add 15 ml of sulphuric acid (4.4), dilute to 100 ml with water and mix.

4.11 Silicon standard solution, 1 g/l.

Prepare a 1 g/l silicon standard solution by using one of the procedures described in 4.11.1 or 4.11.2.

4.11.1 Preparation with silica

Weigh to the nearest 0,1 mg, 2,139 3 g of freshly calcined high-purity silica (> 99,9 % SiO ) and transfer

to a platinum crucible.
2 © ISO 2016 – All rights reserved
---------------------- Page: 6 ----------------------
ISO 4829-2:2016(E)

The high-purity silica shall be calcined for 1 h at 1 100 °C and cooled in a desiccator immediately before

use.

Mix thoroughly with 16 g of anhydrous sodium carbonate and fuse at 1 050 °C for 30 min. Extract the

fusion product with 100 ml of water in a polypropylene or polytetrafluoroethylene beaker.

NOTE Extraction of the fusion product might require gentle heating.

Transfer the extract, which should contain no trace of residue, into a 1 000 ml one-mark volumetric

flask, dilute to the mark with water and mix. Transfer immediately into a well-stoppered

polytetrafluoroethylene bottle for storage.
1 ml of this standard solution contains 1 mg of silicon.
4.11.2 Preparation with ammonium hexafluorosilic
...

DRAFT INTERNATIONAL STANDARD
ISO/DIS 4829-2
ISO/TC 17/SC 1 Secretariat: JISC
Voting begins on: Voting terminates on:
2013-12-12 2014-05-12
Steel and irons — Determination of total silicon content —
Reduced molybdosilicate spectrophotometric method —
Part 2:
Silicon contents between 0,01 and 0,05 %

Aciers et fontes — Dosage du silicium total — Méthode spectrophotométrique au molybdosilicate réduit —

Partie 2: Teneurs en silicium comprises entre 0,01 et 0,05 %
[Revision of first edition (ISO 4829-2:1988)]
ICS: 77.080.01
ISO/CEN PARALLEL PROCESSING
This draft has been developed within the International Organization for
Standardization (ISO), and processed under the ISO lead mode of collaboration
as defined in the Vienna Agreement.
This draft is hereby submitted to the ISO member bodies and to the CEN member
bodies for a parallel five month enquiry.

Should this draft be accepted, a final draft, established on the basis of comments

received, will be submitted to a parallel two-month approval vote in ISO and
THIS DOCUMENT IS A DRAFT CIRCULATED
formal vote in CEN.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
To expedite distribution, this document is circulated as received from the
IN ADDITION TO THEIR EVALUATION AS
committee secretariat. ISO Central Secretariat work of editing and text
BEING ACCEPTABLE FOR INDUSTRIAL,
composition will be undertaken at publication stage.
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 4829-2:2013(E)
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. ISO 2013
---------------------- Page: 1 ----------------------
ISO/DIS 4829-2:2013(E)
Copyright notice

This ISO document is a Draft International Standard and is copyright-protected by ISO. Except as

permitted under the applicable laws of the user’s country, neither this ISO draft nor any extract

from it may be reproduced, stored in a retrieval system or transmitted in any form or by any means,

electronic, photocopying, recording or otherwise, without prior written permission being secured.

Requests for permission to reproduce should be addressed to either ISO at the address below or ISO’s

member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Reproduction may be subject to royalty payments or a licensing agreement.
Violators may be prosecuted.
ii © ISO 2013 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/CD 4829-2
Contents Page

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

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

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

3  Principle .................................................................................................................................................1

4  Reagents ................................................................................................................................................2

5  Apparatus...............................................................................................................................................3

6  Sampling ................................................................................................................................................4

7  Procedure...............................................................................................................................................4

8  Expression of results............................................................................................................................7

9  Test report..............................................................................................................................................8

Annex A (informative) Additional information on the international co-operative tests........................................9

Bibliography......................................................................................................................................................10

© ISO 2013 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/CD 4829-2
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.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. 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.

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.

ISO 4829-2 was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 1, Methods of

determination of chemical composition.

This second/third/... edition cancels and replaces the first/second/... edition (ISO 4829-2:1988), [clause(s) /

subclause(s) / table(s) / figure(s) / annex(es)] of which [has / have] been technically revised.

ISO 4829 consists of the following parts, under the general title Steels — Determination of total silicon content

- Reduced molybdosilicate spectrophotometric method:
⎯ Part 1: Silicon contents between 0,05 and 1,0 %
⎯ Part 2: Silicon contents between 0,01 and 0,05 %
iv © ISO 2013 – All rights reserved
---------------------- Page: 4 ----------------------
DRAFT INTERNATIONAL STANDARD ISO/CD 4829-2
Steels — Determination of total silicon content - Reduced
molybdosilicate spectrophotometric method — Part 2: Silicon
contents between 0,01 and 0,05 %
1 Scope

This International Standard specifies a spectrophotometric method using reduced molybdosilicate for the

determination of total silicon in steels.

The method is applicable to silicon contents between 0,01 and 0,05 % (mass fraction) in steels.

2 Normative references

The following referenced documents are indispensable for the application 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 385, Laboratory glassware — Burettes
ISO 648, Laboratory glassware — One mark pipettes.
ISO 1042, Laboratory glassware — One mark volumetric flasks.
ISO 3696, Water for analytical laboratory use - Specification and test methods

ISO 14284, Steel and iron — Sampling and preparation of samples for the determination of chemical

composition.
3 Principle
Dissolution of a test portion in a hydrochloric/nitric acids mixture.

Fusion of the acid-insoluble residue with sodium peroxide. Formation of the oxidized molybdosilicate (yellow)

complex in weak acid solution.

Selective reduction of the molybdosilicate complex to a blue complex with ascorbic acid, after increasing the

sulphuric acid concentration and adding oxalic acid to prevent the interference of phosphorus, arsenic and

vanadium.

Spectrophotometric measurement of the reduced blue complex at a wavelength of about 810 nm.

© ISO 2013 – All rights reserved
---------------------- Page: 5 ----------------------
ISO/CD 4829-2
4 Reagents

During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only grade

2 water as specified in ISO 3696. Water demineralized by ion-exchange shall not be used as it may contain

significant amounts of colloidal silica.

Reagents supplied in glass bottles, once opened, may absorb moisture and become reactive to glassware.

Alkaline reagents, e.g. sodium carbonate and sodium peroxide, are particularly susceptible. To avoid the risk

of significant contamination arising from this source, it is recommended that only freshly opened bottles of all

reagents be used for the preparation of reagent solutions.

To avoid adventitious contamination, the water shall be prepared, as required, for the specific purpose, and

collected in polypropylene containers for immediate use.

All solutions shall be freshly prepared and stored in polypropylene or polytetrafluoroethylene containers.

4.1 Pure iron, silicon content less than 2 µg/g
4.2 Sodium peroxide, particle size of minus 500 µm
4.3 Sulphuric acid, ρ approximately 1,84 g/ml, diluted 1 + 3

To 600 ml of water while stirring, add cautiously, 250 ml of sulphuric acid, ρ approximately 1,84 g/ml. Cool,

dilute to 1 litre and mix.
4.4 Sulphuric acid, ρ approximately 1,84 g/ml, diluted 1 + 19

To 800 ml of water while stirring, add cautiously, 50 ml of sulphuric acid, ρ approximately 1,84 g/ml. Cool,

dilute to 1 litre and mix.
4.5 Hydrochloric/nitric acids mixture

Add 180 ml of hydrochloric acid, ρ approximately 1,19 g/ml, and 65 ml of nitric acid, ρ approximately 1,40 g/ml,

to 500 ml of water. Cool, dilute to 1 litre and mix.
4.6 Ascorbic acid, 20 g/l solution
This solution shall be freshly prepared.
4.7 Oxalic acid, 50 g/l solution

Dissolve 5 g of oxalic acid di-hydrate (C H O • 2H O) in water, dilute to 100 ml and mix.

2 2 4 2
4.8 Hydrogen peroxide, 60 g/l solution
Dilute 200 ml of hydrogen peroxide, 300 g/l, to 1 litre and mix.
4.9 Potassium permanganate, 22,5 g/l solution
This solution shall be filtered before use.
© ISO 2013 – All rights reserved
---------------------- Page: 6 ----------------------
ISO/CD 4829-2
4.10 Sodium molybdate, 25 g/l solution

Dissolve 2,5 g of sodium molybdate di-hydrate (Na MoO • 2H O) in 50 ml of water and filter through a

2 4 2
medium-texture filter paper.

Immediately before use, add 15 ml of sulphuric acid (4.4), dilute to 100 ml and mix.

4.11 Silicon standard solution, 1 g/l

Prepare a 1 g/l silicon standard solution by using one of the procedures described in 4.11.1 or in 4.11.2.

4.11.1 Preparation with silica

Weigh to the nearest 0,1 mg, 2,139 3 g of freshly calcined high-purity silica (> 99,9 % Si0 ) and transfer to a

platinum crucible.

NOTE 1 The high-purity silica shall be calcined for 1 hour at 1 100 °C and cooled in a desiccator immediately before

use.

Mix thoroughly with 16 g of anhydrous sodium carbonate and fuse at 1 050 °C for 30 minutes. Extract the

fusion product with 100 ml of water in a polypropylene or polytetrafluoroethylene beaker

NOTE 2 Extraction of the fusion product may require gentle heating.

Transfer the extract, which should contain no trace of residue, into a 1 000 ml one-mark volumetric flask,

dilute to the mark with water and mix. Transfer immediately into a well-stoppered polytetrafluoroethylene bottle

for storage.
1 ml of this standard solution contains 1 mg of silicon.
4.11.2 Preparation with ammonium hexafluorosilicate

Dry several grams of ammonium hexafluorosilicate [(NH ) SiF ] in an oven at 105 °C to 110 °C for about

4 2 6
1 hour and cool to room temperature in a desiccator.

Using a suitable plastic beaker, dissolve 3,171 g of the dried product in hot water (~ 80 °C).

Allow to cool and transfer the solution quantitatively into a polyethylene 500 ml one-mark volumetric flask,

dilute to the mark with water and mix well.
1 ml of this standard solution contains 1 mg of silicon.
4.12 Silicon standard solution containing, 20 mg/l

Transfer 10,0 ml of one of the silicon standard solutions (4.11.1 or 4.11.2) into a 500 ml one-mark volumetric

flask. Dilute to the mark and mix. Transfer immediately to a well-stoppered polytetrafluoroethylene bottle for

immediate use.
1 ml of this standard solution contains 20 µg of silicon.
5 Apparatus
Ordinary laboratory apparatus and:
© ISO 2013 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/CD 4829-2
...

NORME ISO
INTERNATIONALE 4829-2
Deuxième édition
2016-02-15
Aciers — Détermination du
silicium total — Méthode
spectrophotométrique au
silicomolybdate réduit —
Partie 2:
Teneurs en silicium comprises entre
0,01 % et 0,05 %
Steels — Determination of total silicon contents — Reduced
molybdosilicate spectrophotometric method —
Part 2: Silicon contents between 0,01 % and 0,05 %
Numéro de référence
ISO 4829-2:2016(F)
ISO 2016
---------------------- Page: 1 ----------------------
ISO 4829-2:2016(F)
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2016, Publié en Suisse

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni utilisée

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l’internet ou sur un Intranet, sans autorisation écrite préalable. Les demandes d’autorisation peuvent être adressées à l’ISO à

l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
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 2016 – Tous droits réservés
---------------------- Page: 2 ----------------------
ISO 4829-2:2016(F)
Sommaire Page

Avant-propos ..............................................................................................................................................................................................................................iv

1 Domaine d’application ................................................................................................................................................................................... 1

2 Références normatives ................................................................................................................................................................................... 1

3 Principe .......................................................................................................................................................................................................................... 1

4 Réactifs ........................................................................................................................................................................................................................... 1

5 Appareillage .............................................................................................................................................................................................................. 3

6 Prélèvement .............................................................................................................................................................................................................. 4

7 Mode opératoire.................................................................................................................................................................................................... 4

7.1 Prise d’essai ............................................................................................................................................................................................... 4

7.2 Essai à blanc .............................................................................................................................................................................................. 4

7.3 Détermination ......................................................................................................................................................................................... 4

7.3.1 Mise en solution de la prise d’essai ................................................................................................................. 4

7.3.2 Traitement du résidu insoluble ........................................................................................................................... 5

7.3.3 Préparation de la solution pour essai ............................................................................................................ 5

7.3.4 Développement de la coloration ........................................................................................................................ 5

7.3.5 Mesurages spectrophotométriques ................................................................................................................. 6

7.4 Etablissement de la courbe d’étalonnage ........................................................................................................................ 6

7.4.1 Préparation des solutions d’étalonnage ...................................................................................................... 6

7.4.2 Mesurages spectrophotométriques ................................................................................................................. 7

7.4.3 Tracé de la courbe d’étalonnage ......................................................................................................................... 7

8 Expression des résultats............................................................................................................................................................................... 7

8.1 Méthode de calcul ................................................................................................................................................................................. 7

8.2 Fidélité ........................................................................................................................................................................................................... 7

9 Rapport d’essai ....................................................................................................................................................................................................... 8

Annexe A (informative) Informations supplémentaires sur l’essai inter laboratoire ......................................9

Bibliographie ...........................................................................................................................................................................................................................10

© ISO 2016 – Tous droits réservés iii
---------------------- Page: 3 ----------------------
ISO 4829-2:2016(F)
Avant-propos

L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes

nationaux de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est

en général confiée aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude

a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,

gouvernementales et non gouvernementales, en liaison avec l’ISO participent également aux travaux.

L’ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui

concerne la normalisation électrotechnique.

Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont

décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents

critères d’approbation requis pour les différents types de documents ISO. Le présent document a été

rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www.

iso.org/directives).

L’attention est appelée sur le fait que certains des éléments du présent document peuvent faire l’objet de

droits de propriété intellectuelle ou de droits analogues. L’ISO ne saurait être tenue pour responsable

de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant

les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de

l’élaboration du document sont indiqués dans l’Introduction et/ou dans la liste des déclarations de

brevets reçues par l’ISO (voir www.iso.org/brevets).

Les appellations commerciales éventuellement mentionnées dans le présent document sont données

pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer

un engagement.

Pour une explication de la signification des termes et expressions spécifiques de l’ISO liés à

l’évaluation de la conformité, ou pour toute information au sujet de l’adhésion de l’ISO aux principes

de l’OMC concernant les obstacles techniques au commerce (OTC), voir le lien suivant: Avant-propos —

Informations supplémentaires.

Le comité chargé de l’élaboration du présent document est l’ISO/TC 17, Aciers, Sous-comité SC 1,

Méthodes de détermination de la composition chimique.

Cette deuxième édition annule et remplace la première édition (ISO 4829-2:1988), qui a fait l’objet d’une

révision technique.

L’ISO 4829 comprend les parties suivantes, présentées sous le titre général Aciers — Détermination du

silicium total — Méthode spectrophotométrique au silicomolybdate réduit:
— Partie 1: Teneurs en silicium comprises en 0,05 % et 1,0 %
— Partie 2: Teneurs en silicium comprises entre 0,01 % et 0,05 %
iv © ISO 2016 – Tous droits réservés
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NORME INTERNATIONALE ISO 4829-2:2016(F)
Aciers — Détermination du silicium total — Méthode
spectrophotométrique au silicomolybdate réduit —
Partie 2:
Teneurs en silicium comprises entre 0,01 % et 0,05 %
1 Domaine d’application

La présente partie de l’ISO 4829 spécifie une méthode spectrophotométrique au silicomolybdate réduit

pour la détermination du silicium total dans les aciers.

La méthode est applicable aux teneurs en silicium comprises entre 0,01 % et 0,05 % (fraction massique)

dans les aciers.
2 Références normatives

Les documents suivants, en tout ou partie, sont référencés de façon normative dans le présent document

et sont indispensables à son application. Pour les références datées, seule l’édition citée s’applique.

Pour les références non datées, la dernière édition du document de référence s’applique (y compris les

éventuels amendements).
ISO 648, Verrerie de laboratoire — Pipettes à un volume
ISO 1042, Verrerie de laboratoire — Fioles jaugées à un trait

ISO 3696, Eau pour laboratoire à usage analytique — Spécification et méthodes d’essai

ISO 14284, Fontes et aciers — Prélèvement et préparation des échantillons pour la détermination de la

composition chimique
3 Principe

Mise en solution d’une prise d’essai par un mélange d’acide chlorhydrique/acide nitrique.

Fusion du résidu insoluble dans l’acide avec du peroxyde de sodium. Formation du complexe

silicomolybdique oxydé (jaune) dans une solution faiblement acide.

Réduction sélective du complexe silicomolybdique en un complexe, coloré en bleu, par l’acide ascorbique,

après augmentation de la concentration en acide sulfurique et addition d’acide oxalique afin d’éliminer

l’interférence du phosphore, de l’arsenic et du vanadium.

Mesurage spectrophotométrique du complexe réduit, coloré en bleu, à une longueur d’onde voisine de

810 nm.
4 Réactifs

Au cours de l’analyse, sauf indication contraire, utiliser uniquement des réactifs de qualité

analytique reconnue et seulement de l’eau distillée de grade 2 selon la spécification de l’ISO 3696.

L’eau déminéralisée par échange d’ions ne doit pas être utilisée, car elle peut contenir une quantité

importante de silice colloïdale.
© ISO 2016 – Tous droits réservés 1
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ISO 4829-2:2016(F)

Les réactifs conservés dans des récipients en verre, une fois ouverts, peuvent absorber de l’humidité et

réagir avec la verrerie. Les réactifs alcalins, tels le carbonate de sodium et le peroxyde de sodium, sont

particulièrement susceptibles de réagir. Pour éviter le risque de contamination importante provenant

de ces sources, il est recommandé de n’utiliser que des récipients fraîchement ouverts de tous les

produits à utiliser, pour préparer les solutions des réactifs.

Pour éviter toute contamination accidentelle, l’eau doit être préparée pour chaque série d’analyse et

être conservée dans un récipient en polypropylène pour l’emploi immédiat.

Toutes les solutions doivent être fraîchement préparées et conservées dans des récipients en

polypropylène ou en polytétrafluoroéthylène.
4.1 Fer pur, à teneur en silicium inférieure à 2 μg/g.
4.2 Peroxyde de sodium, granulométrie inférieure à 500 μm.
4.3 Acide sulfurique, ρ 1,84 g/ml environ, dilué 1 + 3.

Ajouter avec précaution, tout en agitant, 250 ml d’acide sulfurique, ρ 1,84 g/ml environ, à 600 ml d’eau.

Refroidir, diluer à 1 l avec de l’eau, et homogénéiser.
4.4 Acide sulfurique, ρ 1,84 g/ml environ, dilué 1 + 19.

Ajouter avec précaution, tout en agitant, 50 ml d’acide sulfurique, ρ 1,84 g/ml environ, à 800 ml d’eau.

Refroidir, diluer à 1 l avec de l’eau, et homogénéiser.
4.5 Mélange d’acides chlorhydrique et nitrique.

Ajouter 180 ml d’acide chlorhydrique, ρ 1,19 g/ml environ, et 65 ml d’acide nitrique, ρ 1,40 g/ml environ,

à 500 ml d’eau. Refroidir, diluer à 1 l avec de l’eau, et homogénéiser.
4.6 Acide ascorbique, solution à 20 g/l.
Cette solution doit être préparée au moment de l’emploi.
4.7 Acide oxalique, solution à 50 g/l.

Dissoudre 5 g d’acide oxalique di-hydraté (C H O ·2H O) dans de l’eau, diluer à 100 ml avec de l’eau, et

2 2 4 2
homogénéiser.
4.8 Peroxyde d’hydrogène, solution à 60 g/l.

Diluer 200 ml de peroxyde d’hydrogène à 300 g/l, à 1 l avec de l’eau, et homogénéiser.

4.9 Permanganate de potassium, solution à 22,5 g/l.

Cette solution doit être filtrée avant emploi afin d’éliminer les fines particules de MnO qui peuvent être

présentes dans la solution, car celles-ci vont interférer lors du mesurage.
4.10 Molybdate de sodium, solution à 25 g/l.

Dissoudre 2,5 g de molybdate de sodium di-hydraté (Na MoO ·2H O) dans 50 ml d’eau et filtrer sur un

2 4 2
papier filtre de texture moyenne.

Immédiatement avant l’emploi, ajouter 15 ml d’acide sulfurique (4.4), diluer à 100 ml avec de l’eau et

homogénéiser.
2 © ISO 2016 – Tous droits réservés
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ISO 4829-2:2016(F)
4.11 Solution étalon de silicium à 1 g/l.

Préparer une solution étalon de silicium à 1 g/l, en utilisant l’une des procédures décrites en 4.11.1 ou

4.11.2.
4.11.1 Préparation à partir de silice

Peser, à 0,1 mg près, 2,139 3 g de silice haute pureté, fraîchement calcinée (> 99,9 % SiO ) et les

introduire dans un creuset en platine.

Immédiatement avant l’emploi, calciner la silice de haute pureté pendant 1 h à 1 100° C et refroidir dans

un dessiccateur.

Mélanger parfaitement avec 16 g de carbonate de sodium anhydre et faire fondre à 1 050° C pendant

30 min. Reprendre le produit de fusion par 100 ml d’eau dans un bécher en polypropylène ou en

polytétrafluoroéthylène.
NOTE La reprise du produit de fusion peut exiger un chauffage modéré.

Transvaser la solution de reprise, qui ne doit contenir aucune trace de résidu, dans une fiole jaugée

de 1 000 ml, compléter au volume avec de l’eau et homogénéiser. Transvaser immédiatement dans un

flacon en polytétrafluoroéthylène convenablement bouché pour le stockage.
1 ml de cette solution étalon contient 1 mg de silicium.
4.11.2 Préparation à partir d’hexafluorosilicate d’ammonium

Sécher plusieurs grammes d’hexafluorosilicate d’ammonium [(NH ) SiF ] pendant environ 1 h dans

4 2 6

une étuve réglée entre 105 °C et 110 °C et refroidir à température ambiante dans un dessiccateur.

Peser, à 0,1 mg près, 3,171 0 g du produit sec. L
...

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