ISO 14420:2020

Carbonaceous products for the production of aluminium - Baked anodes and shaped carbon products - Determination of the coefficient of linear thermal expansion

This document specifies a method to determine the coefficient of linear thermal expansion of carbonaceous or graphite materials (solid materials) for the production of aluminium between 20 °C and 300 °C. It applies to baked anodes and shaped carbon products.

Produits carbonés utilisés pour la production de l'aluminium — Anodes cuites et produits carbonés formés — Détermination du coefficient de dilatation thermique

General Information

• Status: Published
• Publication Date: 04-Mar-2020
• ICS: 71.100.10 - Materials for aluminium production
• Technical Committee: ISO/TC 226 - Materials for the production of primary aluminium
• Drafting Committee: ISO/TC 226 - Materials for the production of primary aluminium
• Current Stage: 9060 - Close of review
• Completion Date: 02-Sep-2030

Relations

• Revises: ISO 14420:2005 - Carbonaceous products for the production of aluminium - Baked anodes and shaped carbon products - Determination of the coefficient of linear thermal expansion
• Effective Date: 04-Nov-2015

Overview

ISO 14420:2020 specifies a standardized laboratory method to determine the coefficient of linear thermal expansion (CLTE) of carbonaceous and graphite materials used in aluminium production - specifically baked anodes and shaped carbon products. The method covers measurements between 20 °C and 300 °C using a push‑rod dilatometer, and defines specimen preparation, apparatus, calibration, measurement, evaluation and reporting requirements.

Keywords: ISO 14420:2020, coefficient of linear thermal expansion, baked anodes, shaped carbon products, aluminium production, dilatometer, thermal expansion testing.

Key topics and technical requirements

• Scope and principle
  • Determines average CLTE for solid carbonaceous/graphite materials between 20 °C and 300 °C.
  • Uses a push‑rod dilatometer with a low‑expansivity sample holder (e.g., flint glass) transmitting length change to an external measuring system.
• Apparatus accuracy
  • Length‑measurement device with error limits around ±0.5 µm for dilatometer output; vernier calliper per ISO 13385‑1 for initial lengths (error limit ±0.2%).
  • Furnace stability: temperature held within ±0.5% along specimen length.
  • Temperature measurement accuracy: thermocouple or equivalent within ±0.5%.
• Specimen preparation
  • Cylindrical or prismatic specimens; length ≥ 25 mm (preferably 50–120 mm).
  • Transverse dimensions at least twice the largest structural constituent and not smaller than 4 mm.
  • End surfaces machined to plane‑parallelism within 0.2 mm.
  • Optional stress relief by annealing at 1 000 °C in a non‑oxidizing atmosphere.
• Procedure
  • Calibration using calibrated reference samples.
  • Zeroing of the measuring system, heating to the upper temperature limit, recording length change, and correcting for sample‑holder/push‑rod expansion.
• Evaluation and precision
  • Average CLTE computed from measured length change, original length and temperature interval, accounting for apparatus expansion.
  • Reported precision (interlaboratory): repeatability r = 0.10 × 10^‑6 K^‑1; reproducibility R = 0.17 × 10^‑6 K^‑1.
• Test report content
  • Must include sample ID, reference to ISO 14420:2020, pre‑treatment, specimen count, temperature range, CLTE values (units 10^‑6 K^‑1), deviations and test date.

Applications and users

• Quality control and specification acceptance for baked anodes, carbon electrodes and shaped carbon products in aluminium smelting.
• Materials R&D for graphite/carbon product development and process optimization.
• Metrology and testing laboratories performing thermal‑expansion characterization.
• Process engineers, materials scientists and procurement teams specifying CLTE for thermal compatibility in potline components.

Related standards

• ISO 13385‑1 (dimensional measuring equipment - callipers)
• DIN 51909:2009 (basis for this document)
• ASTM E691 (precision assessment method referenced)

ISO 14420:2020 helps ensure consistent, comparable CLTE data for carbonaceous materials used in aluminium production, supporting reliable component design, quality control and materials selection.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 14420
Second edition
2020-03
Carbonaceous products for the
production of aluminium — Baked
anodes and shaped carbon products
— Determination of the coefficient of
linear thermal expansion
Produits carbonés utilisés pour la production de l'aluminium —
Anodes cuites et produits carbonés formés — Détermination du
coefficient de dilatation thermique
Reference number
©
ISO 2020
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ii © ISO 2020 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 2
6 Specimens . 3
7 Procedure. 3
7.1 Calibration . 3
7.2 Measurement . 3
8 Evaluation . 3
9 Precision . 4
10 Test report . 4
Bibliography . 5
Foreword
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This document was prepared by Technical Committee ISO/TC 226, Materials for the production of
primary aluminium.
This second edition cancels and replaces the first edition (ISO 14420:2005), of which it constitutes a
minor revision.
The main changes to the previous edition are as follows:
— 5.4 has been revised to remove micrometer calliper;
— the formulae in Clause 9, previously Clause 10, have been revised;
— Clause 10, previously Clause 9, has been revised according to ISO/IEC Directives Part 2.
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 2020 – All rights reserved

Introduction
This document is based on DIN 51909:2009.
INTERNATIONAL STANDARD ISO 14420:2020(E)
Carbonaceous products for the production of
aluminium — Baked anodes and shaped carbon products
— Determination of the coefficient of linear thermal
expansion
1 Scope
This document specifies a method to determine the coefficient of linear thermal expansion of
carbonaceous or graphite materials (solid materials) for the production of aluminium between 20 °C
and 300 °C. It applies to baked anodes and shaped carbon products.
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 13385-1, Geometrical product specifications (GPS) — Dimensional measuring equipment — Part 1:
Design and metrological characteristics of callipers
DIN 1333, Presentation of numerical data
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
...