ISO 11706:2012

Carbonaceous materials for the production of aluminium - Prebaked anodes - Determination of the fracture energy

ISO 11706:2012 describes a method for the determination of the fracture energy at room temperature. This property is relevant for the thermal shock resistance of prebaked anodes used in the electrolytic cell.

Produits carbonés pour la production de l'aluminium - Anodes précuites - Détermination de l'énergie de rupture

General Information

• Status: Published
• Publication Date: 29-Aug-2012
• 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/WG 2 - Cathodes and ramming paste
• Current Stage: 9093 - International Standard confirmed
• Start Date: 23-May-2023
• Completion Date: 13-Dec-2025

Overview

ISO 11706:2012 is an international standard that specifies a method for determining the fracture energy of prebaked carbonaceous anodes used in aluminium production. This test is performed at room temperature and measures the energy required to fracture a notched cylindrical test piece. The fracture energy is a critical property indicating the thermal shock resistance of prebaked anodes, which are essential components in electrolytic cells for aluminium smelting. By providing a standardized testing procedure, ISO 11706:2012 ensures consistent assessment of anode durability and performance.

Key Topics

• Scope and Purpose
  The standard focuses exclusively on the determination of fracture energy at ambient temperature to assess thermal shock resistance of prebaked anodes used in aluminium electrolytic cells.

• Test Method Principle
  The fracture energy is calculated by integrating the force-displacement data collected during a controlled 3-point bending test of a notched cylindrical specimen. The notching reduces stored elastic energy and facilitates stable crack propagation.

• Test Specimen Preparation
  Cylindrical test pieces with a 50 mm diameter and minimum 130 mm length are precisely drilled, cut with flat ends, and notched at a 60° angle with a 2 mm slot width. Specimens are cleaned, dried at 120 °C, and then cooled before testing.

• Test Setup and Equipment
  The 3-point bending setup complies with ISO 12986-1. Key equipment includes a hydraulic testing machine with load control, displacement sensors accurate to 5 µm, and data acquisition systems to record force and displacement.

• Calculation and Reporting
  Fracture energy is computed using the integral of force over displacement normalized by the broken surface area, with results expressed in Joules per meter (J/m). Test reports must include detailed specimen information, fracture energy values, and test conditions.

Applications

ISO 11706:2012 serves aluminium production industries by providing a reliable method to evaluate the mechanical integrity of prebaked carbon anodes. The fracture energy measurement helps:

• Improve Anode Quality
  Manufacturers can monitor and enhance the fracture resistance of prebaked anodes, reducing failure during thermal cycling in electrolytic cells.

• Optimize Production Processes
  By assessing anode durability, plants can refine raw material selection, baking processes, and quality control procedures.

• Ensure Operational Safety
  High thermal shock resistance minimizes anode cracking risks, contributing to safer, more stable electrolytic cell operations.

• Support Supplier and Buyer Agreements
  Standardized testing facilitates clear communication and quality assurance between anode suppliers and aluminium smelters.

Related Standards

• ISO 8007-2: Sampling plans and methods for carbonaceous materials, including prebaked anodes. This guides how test specimens should be sampled for reproducibility and accuracy.

• ISO 12986-1: Specifies the three-point bending method for determining bending and shear strength of prebaked anodes and cathode blocks, complementing fracture energy testing.

• ISO 12985-1: Defines measurement of apparent density using dimensional methods for baked anodes and cathode blocks, another parameter critical for assessing carbonaceous material quality.

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ISO 11706:2012 is essential for professionals involved in aluminium smelting, quality assurance, and materials research, providing a standardized, practical methodology for evaluating the fracture energy and thermal shock resistance of prebaked anodes. Implementing this standard can lead to improved anode performance, reduced operational downtime, and enhanced overall efficiency in aluminium production.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 11706
First edition
2012-09-01
Carbonaceous materials for the
production of aluminium — Prebaked
anodes — Determination of the
fracture energy
Produits carbonés pour la production de l’aluminium - Anodes
précuites - Détermination de l’énergie de rupture
Reference number
©
ISO 2012
© ISO 2012
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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
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electrotechnical standardization.
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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 11706 was prepared by Technical Committee ISO/TC 226, Materials for the production of primary
aluminium.
INTERNATIONAL STANDARD ISO 11706:2012(E)
Carbonaceous materials for the production of
aluminium — Prebaked anodes — Determination of the
fracture energy
1 Scope
This International Standard describes a method for the determination of the fracture energy at room
temperature. This property is relevant for the thermal shock resistance of prebaked anodes used in the
electrolytic cell.
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 8007-2, Carbonaceous materials used in the production of aluminium — Sampling plans and sampling
from individual units — Part 2: Prebaked anodes
ISO 12986-1, Carbonaceous materials used in the production of aluminium — Prebaked anodes and cathode
blocks — Part 1: Determination of bending/shear strength by a three-point method
ISO 12985-1, Carbonaceous materials used in the production of aluminium — Baked anodes and cathode
blocks — Part 1: Determination of apparent density using a dimensions method
3 Principle
The amount of energy needed to fracture a notched cylindrical test piece is determined by integrating
the force-displacement signals of the testing machine.
Notching of the test piece allows to minimize the elastic energy stored in the specimen and therefore
guarantees controlled and smooth crack propagation.
The same arrangement and testing equipment as required for the determination of the bending/shear
strength by a 3-point method can be used, see ISO 12986-1.
A length measurement device for the vertical displacement, a data acquisition system and software able
to integrate the force-displacement curve are additionally needed.
4 Apparatus
4.1 Testing equipment
The testing machine has a hydraulic system that can be adjusted to control the load increa
...