EN ISO 21068-1:2008

SLOVENSKI STANDARD
01-december-2008
Kemijska analiza surovin in ognjevzdržnih izdelkov s silicijevim karbidom - 1. del:
Splošne informacije in priprava vzorcev (ISO 21068-1:2008)
Chemical analysis of silicon-carbide-containing raw materials and refractory products -
Part 1: General information and sample preparation (ISO 21068-1:2008)
Chemische Analyse von Siliciumcarbid enthaltenden Rohstoffen und feuerfesten
Erzeugnissen - Teil 1: Allgemeine Angaben und Probenvorbereitung (ISO 21068-1:2008)
Analyse chimique des matières premières et des produits réfractaires contenant du
carbure de silicium - Partie 1: Informations générales et préparation des échantillons
(ISO 21068-1:2008)
Ta slovenski standard je istoveten z: EN ISO 21068-1:2008
ICS:
81.080 Ognjevzdržni materiali Refractories
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 21068-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2008
ICS 81.080
English Version
Chemical analysis of silicon-carbide-containing raw materials
and refractory products - Part 1: General information and sample
preparation (ISO 21068-1:2008)
Analyse chimique des matières premières et des produits Chemische Analyse von Siliciumcarbid enthaltenden
réfractaires contenant du carbure de silicium - Partie 1: Rohstoffen und feuerfesten Erzeugnissen - Teil 1:
Informations générales et préparation des échantillons (ISO Allgemeine Angaben und Probenvorbereitung (ISO 21068-
21068-1:2008) 1:2008)
This European Standard was approved by CEN on 11 July 2008.
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 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 Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21068-1:2008: E
worldwide for CEN national Members.

Contents Page
Foreword.3

Foreword
This document (EN ISO 21068-1:2008) has been prepared by Technical Committee ISO/TC 33 "Refractories"
in collaboration with Technical Committee CEN/TC 187 “Refractory products and materials” 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 February 2009, and conflicting national standards shall be withdrawn
at the latest by February 2009.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] 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, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 21068-1:2008 has been approved by CEN as a EN ISO 21068-1:2008 without any
modification.
INTERNATIONAL ISO
STANDARD 21068-1
First edition
2008-08-01
Chemical analysis of silicon-carbide-
containing raw materials and refractory
products —
Part 1:
General information and sample
preparation
Analyse chimique des matières premières et des produits réfractaires
contenant du carbure de silicium —
Partie 1: Informations générales et préparation des échantillons

Reference number
ISO 21068-1:2008(E)
©
ISO 2008
ISO 21068-1:2008(E)
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ii © ISO 2008 – All rights reserved

ISO 21068-1:2008(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.3
3 Definitions .3
4 Sampling and preparation of the test sample .4
4.1 General .4
4.2 Sample pretreatment.4
5 Preliminary analyses.5
6 Expression of results.6
7 Test report.6
Bibliography.7

ISO 21068-1:2008(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.
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 21068-1 was prepared by Technical Committee ISO/TC 33, Refractories
ISO 21068 consists of the following parts, under the general title Chemical analysis of silicon-carbide-
containing raw materials and refractory products:
⎯ Part 1: General information and sample preparation
⎯ Part 2: Determination of loss on ignition, total carbon, free carbon and silicon carbide, total and free silica
and total and free silicon
⎯ Part 3: Determination of nitrogen, oxygen and metallic and oxidic constituents
iv © ISO 2008 – All rights reserved

ISO 21068-1:2008(E)
Introduction
[2]
ISO 21068, Parts 1 to 3, have been developed from the combination of a Japanese standard JIS 2011 and
work items originally developed within CEN. As there is a wide variety of laboratory equipment in use, the
most commonly used methods are described.
ISO 21068, Parts 1 to 3, are applicable to the analysis of all refractory products as classified in
[10] to [13] [3]
ISO 10081 (shaped) and ISO 1927 (unshaped) and raw materials containing carbon and/or silicon
carbide. Therefore, ISO 21068, Parts 1 to 3, covers the full range of analysis from pure silicon carbide to
oxidic refractory composition with low-content silicon carbide and/or nitrides. Primarily, ISO 21068, Parts 1 to
3, provides methods to distinguish between different carbon bound types like total carbon (C ) and free
total
carbon (C ) and derives from these two the silicon carbide content.
free
If free carbon is present, the standard includes different types of temperature treatment in order to determine
the mass changes gravimetrically. Frequently, the resulting residue is used for other determinations.
The determination of other groups of analytes described in ISO 21068, Parts 1 to 3, are free metals, free
silicon (S ), free aluminum (Al ), free magnesium (Mg ), free iron (Fe ) and the group of oxides from
ifree free free free
main to trace components.
ISO 21068, Parts 1 to 3, also describe the chemical analysis of silicon dioxide, total silicon, oxygen and
nitrogen and other oxidic bound metals that typically occur in the materials.
It represents a listing of analytical methods which is approximately structured according to material
composition. However, it is still the user who should prove the applicability of the method depending on the
material and analytical requirements.
The most broadly used analytical techniques such as X-ray fluorescence spectroscopy (XRF) and inductively
coupled plasma-optical emission spectrometry (ICP-OES) suffer from the disadvantage that the analytical
results are chemical bond independent. For carbon-containing ceramic raw materials and compositions
ISO 21068, Parts 1 to 3, provide analytical methods for the determination of free carbon, and SiC in the
presence of oxidic compounds in particular SiO .
Because of the diversity of laboratory equipment, the three parts of ISO 21068 summarize broadly used
analytical techniques which lead to equivalent results. In principle, the determination of carbon is based in all
itemized methods on the oxygen extraction method, where carbon is oxidized at elevated temperatures.
Thereafter carbon is analysed as CO .
As well as carbon and carbidic compounds, metallic silicon, aluminium and magnesium are considered. While
metallic silicon is in majority a precursor material which remains after the production process of SiC in the raw
material, metallic aluminium is added as an antioxidant in carbon-containing refractory formulations.
Mostly oxidic bound components, such as Al O , CaO, MgO, TiO , Cr O , ZrO and alkalines, can be
2 3 2 2 3 2
[25]
determined by XRF as described in ISO 12677, ICP-AES or wet chemical methods (see ISO 26845 ,
[22] [24]
ISO 21587-1 and ISO 21587-3 ). These results can be corrected by formulas provided by ISO 21068,
Parts 1 to 3, in consideration of the values obtained by the determination of carbon, SiC, and metallic
components.
ISO 21068, Parts 1 to 3, also provide methods for qualitative and quantitative determinations of the nitrogen
content and the determination of oxygen. Thereby only the total content of nitrogen and oxygen is given; a
precise determination of non-carbide components (oxides and nitrides) is not possible in this way.
ISO 21068, Parts 1 to 3, do not provide methods to distinguish quantitatively between different varieties of
nitrides like silicon nitride, silicon oxy-nitride and sialon. For further inform
...