ISO 14428:2005

INTERNATIONAL ISO
STANDARD 14428
First edition
2005-08-15
Corrected version
2007-06-15

Carbonaceous materials for the
production of aluminium — Cold and
tepid ramming pastes —
Expansion/shrinkage during baking
Produits carbonés utilisés pour la production de l'aluminium — Pâtes de
brasquage froides et tièdes — Expansion/rétrécissement durant la
cuisson




Reference number
ISO 14428:2005(E)
©
ISO 2005

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ISO 14428:2005(E)
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ii © ISO 2005 – All rights reserved

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ISO 14428:2005(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
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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 14428 was prepared by Technical Committee ISO/TC 226, Materials for the production of primary
aluminium.
This corrected version of ISO 14428:2005 incorporates the following correction:
⎯ The publication date has been changed to 2005.
© ISO 2005 – All rights reserved iii

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ISO 14428:2005(E)
Introduction
The expansion/shrinkage of ramming pastes used in the production of aluminium is an important property,
because excessive shrinkage can cause cracks in the baked paste serving as a lining material in alumina
electrolysis cells. These cracks can cause leakage of the liquid bath, destroying the sidewall lining and the
steel shell and thus leading to shut-down of the cell. Ramming pastes change phase from plastic to non-
plastic between 400 °C and 600 °C (200 °C and 300 °C for resin binders). The shrinkage which occurs
between the temperature at which the paste becomes non-plastic and the operating temperature (950 °C) is
an important factor. Apparent shrinkage in the viscous range is due to slumping rather than actual shrinkage.
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INTERNATIONAL STANDARD ISO 14428:2005(E)

Carbonaceous materials for the production of aluminium —
Cold and tepid ramming pastes — Expansion/shrinkage during
baking
1 Scope
This International Standard specifies the determination of expansion/shrinkage during baking of cold and tepid
ramming pastes used in the production of aluminium.
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 14422, Carbonaceous materials used in the production of aluminium — Cold-ramming pastes — Methods
of sampling
ISO 14427, Carbonaceous materials used in the production of aluminium — Cold and tepid ramming
pastes — Preparation of unbaked test specimens and determination of apparent density after compaction
ASTM E220, Standard Test Method for Calibration of Thermocouples by Comparison Techniques
3 Principle
The change in height of a rammed sample of paste is measured at temperatures increasing to 950 °C, with a
holding period of 3 h at the highest temperature. The shrinkage of the paste between the temperature at which
the paste has become non-plastic and at 950 °C (both before and after the holding period) is determined.
4 Apparatus and materials
4.1 Device for measuring the sample length, accurate to ± 0,1 mm.
−5
4.2 Push-rod dilatometer, capable of determining changes in length of the specimen of 2 × 10 l (i.e.
0
1 µm for 50 mm length).
The contact force of the extensometer shall not exceed 2 N. The expansion/shrinkage shall be measured
vertically. An example of a vertical dilatometer is given in Figure 1. The dilatometer should preferably consist
of a push rod and an outer tube made of the same material. Vitreous silica is recommended as the material for
the push rod and the outer tube. The gap between the outer tube and the sample shall not be less than 2 mm
and not larger than 10 mm. If the sample-holding assembly is made of vitreous silica, see the precautions
given in 6.2.
No irreversible changes should occur in the material in the temperature range 20 °C to 950 °C.
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ISO 14428:2005(E)

Key
1 extensometer
2 lid
3 push rod
4 outer tube
5 carbon particles
6 disk
7 test specimen, ∅ 50 mm
8 thermocouple
9 furnace
Figure 1 — Example of quartz equipment for measuring thermal expansion/
shrinkage of ramming pastes samples having 50 mm diameter

4.3 Disk, preferably made of the same material as the outer tube, with the same diameter as the sample
± 0,1 mm and (2,0 ± 0,5) mm thick, to be inserted on top of the sample.
If the disk is made of vitreous silica, see the precautions given in 6.2.
4.4 Carbon particles, used to support the sample during heating by filling the gap between the sample and
the reference tube.
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ISO 14428:2005(E)
The particle size shall be < 1 mm. For example, the carbon material could be electrocalcined anthracite or
graphite.
4.5 Furnace
...