ISO 15379-1:2015

INTERNATIONAL ISO
STANDARD 15379-1
Second edition
2015-05-15
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 15379-1:2015(E)
©
ISO 2015

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ISO 15379-1:2015(E)

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ii © ISO 2015 – All rights reserved

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ISO 15379-1:2015(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Principle . 1
4 Apparatus . 1
5 Reagents . 2
6 Samples . 3
7 Procedure. 3
8 Results . 4
8.1 Calculation . 4
8.2 Precision . 4
9 Test report . 4
© ISO 2015 – All rights reserved iii

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ISO 15379-1:2015(E)

Foreword
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editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directives
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The committee responsible for this document is ISO/TC 226, Materials for the production of primary
aluminium.
This second edition cancels and replaces the first edition (ISO 15379-1:2004), which has been technically
revised.
ISO 15379 consists of the following parts, under the general title Carbonaceous materials for the
production of aluminium — Cathode block materials:
— Part 1: Determination of the expansion due to sodium penetration with application of pressure
— Part 2: Determination of the expansion due to sodium penetration without application of pressure
iv © ISO 2015 – All rights reserved

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ISO 15379-1:2015(E)

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 a case, 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 having 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.
© ISO 2015 – All rights reserved v

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INTERNATIONAL STANDARD ISO 15379-1:2015(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 part of ISO 15379 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, 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 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method
for the determination of repeatability and reproducibility of a standard measurement method
ISO 8007-1, Carbonaceous materials used in the production of aluminium — Sampling plans and sampling
from individual units — Part 1: Cathode blocks
ASTM E 220, Standard Test Method for Calibration
...