ISO 12985-2:2018

Overview

ISO 12985-2:2018 is an international standard specifying a hydrostatic method for determining the apparent density and open porosity of carbonaceous materials used in the production of aluminium, specifically baked anodes and cathode blocks. This method is crucial for assessing the quality and performance of carbon products in aluminium manufacturing, ensuring optimal electrical and thermal properties. It is particularly suited for samples with complex or irregular geometry, which often pose challenges during testing.

The standard provides detailed procedures, apparatus requirements, and calculation formulas to accurately measure these physical properties. Accurate determination of density and porosity helps improve product consistency, enhances aluminium production efficiency, and reduces operational risks.

Key Topics

• Hydrostatic method principle: Uses Archimedes’ principle by measuring the buoyant force on water-saturated samples after boiling.
• Apparent density: Defined as the ratio of the dry mass of the sample to its volume, providing insight into material compactness.
• Open porosity: Measures the volume percentage of pores open to water penetration, impacting material durability and performance.
• Sample preparation: Includes drying protocols, boiling to saturate pores, and handling irregular geometries for accurate volume measurements.
• Precision and reproducibility: Specifies repeatability limits (e.g., 0.003 g/cm³ for density, 0.3% for porosity) and reproducibility criteria between laboratories, ensuring reliable and consistent results.
• Required equipment: Hydrostatic balance, heating plates for boiling, drying cabinets, beakers, and thermometers calibrated for room temperature ranges.
• Calculation formulas: Provide standardized methods to convert mass measurements into apparent density and open porosity percentages with high accuracy.
• Sampling methods: References ISO 8007-1 and ISO 8007-2 for obtaining representative carbonaceous material samples from cathode blocks and prebaked anodes.

Applications

ISO 12985-2:2018 is essential for industries involved in the aluminium smelting process and carbon material manufacturing. Key applications include:

• Quality control of carbonaceous baked anodes and cathode blocks to ensure they meet production specifications.
• Material research and development aimed at optimizing porosity and density for enhanced electrical conductivity and mechanical strength.
• Industrial testing laboratories performing standardized assessments of carbon products prior to their use in electrolytic cells.
• Failure analysis by identifying porosity-related defects that may affect lifetime or performance of aluminium production components.
• Compliance verification with industry standards to support procurement and certification processes.

By adopting this hydrostatic testing standard, aluminium producers and carbon material manufacturers can achieve better process control, reduce downtime, and improve final product reliability.

Related Standards

ISO 12985-2:2018 is part of a series of standards addressing carbonaceous materials within aluminium production:

• ISO 12985-1: Baked anodes and cathode blocks - Part 1: Determination of real density and porosity by mercury intrusion method.
• ISO 8007-1: Sampling plans for cathode blocks, relevant for preparing test specimens in compliance with Part 2.
• ISO 8007-2: Sampling plans for prebaked anodes, utilized in conjunction with hydrostatic testing.
• Various parts of ISO 5725, covering the accuracy, precision, and reproducibility of measurement methods ensuring robust analytical results.

Compliance with these interrelated standards supports comprehensive characterization of carbon materials, fostering quality assurance and standardization across the aluminium industry supply chain.

By implementing ISO 12985-2:2018, organizations benefit from a precise, standardized hydrostatic method for density and porosity measurement, enabling enhanced quality assurance and process optimization in aluminium production using carbonaceous materials.