ISO 15379-1:2019

INTERNATIONAL ISO
STANDARD 15379-1
Third edition
2019-12
Carbonaceous materials for the
production of aluminium — Cathode
block materials —
Part 1:
Determination of the expansion due to
sodium penetration with application
of pressure
Produits carbonés utilisés pour la production de l'aluminium — Blocs
cathodiques —
Partie 1: Détermination de l'expansion due à la pénétration du
sodium avec application de pression
Reference number
©
ISO 2019
© ISO 2019
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Published in Switzerland
ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 1
6 Reagents . 3
7 Samples . 3
8 Procedure. 3
9 Results . 4
9.1 Calculation . 4
9.2 Precision . 4
10 Test report . 4
Bibliography . 6
Foreword
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This document was prepared by Technical Committee ISO/TC 226, Materials for the production of
primary aluminium.
This third edition cancels and replaces the second edition (ISO 15379-1:2015), which has been
technically revised. The main changes to the previous edition are as follows:
— ASTM E 220 has been removed from Clause 2 and 5.3;
— minor changes have been made in 6.2, 6.3, 6.4 and 6.5;
— Clause 10 has been aligned with test reports in other ISO/TC 226 standards.
A list of all parts in the ISO 15379 series can be found on the ISO website.
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

Introduction
Expansion due to sodium penetration is an important property of carbon cathode blocks. As soon as
alumina electrolysis starts, sodium penetrates into the carbon cathode blocks causing swelling of these
blocks. This increase in volume creates mechanical stresses within the blocks and/or bulging of the
bottom block plate. This can lead to cracks through which liquid aluminium and/or liquid electrolyte
can flow, reaching the thermal insulation beneath the blocks and destroying these ceramic materials.
In such cases, the electrolysis cell has to be relined, resulting in loss of aluminium production and high
expenses. Therefore, cathode blocks produced with materials allowing only low sodium penetration
and with the lowest possible expansion due to sodium penetration are preferred.
The study can be supplemented by measuring electrical resistivity (see ISO 11713) before and after
the test.
Due to thermal and sodium expansion when heating up the cathode blocks in the electrolysis cells to
operational temperature, the block will be subject to pressure from the steel shell; therefore, in the
present method, 5 MPa is chosen as a realistic maximum pressure.
INTERNATIONAL STANDARD ISO 15379-1:2019(E)
Carbonaceous materials for the production of
aluminium — Cathode block materials —
Part 1:
Determination of the expansion due to sodium penetration
with application of pressure
1 Scope
This document specifies a method that covers the determination of linear expansion under external
pressure due to sodium penetration in cathode-block materials used in the production of aluminium.
The linear expansion of the blocks depends on the sampling direction due to anisotropy.
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 8007-1, Ca
...