Overview - ISO/TS 10719:2016 (Cast irons, non-combined carbon)
ISO/TS 10719:2016 specifies an infrared absorption method after combustion in an induction furnace to determine non-combined carbon (graphitic carbon) in cast irons. The method is applicable to non-combined carbon contents between 1.0 % and 3.0 % (mass fraction). It describes sample preparation, chemical dissolution, filtration of the graphite fraction, combustion of the collected residue in a high‑frequency induction furnace and measurement of the evolved CO2/CO by infrared absorption.
Key topics and technical requirements
- Scope and limits: Target range 1.0–3.0 % non‑combined carbon; some heavily alloyed or extensively heat‑treated cast irons containing insoluble carbides may yield elevated non‑combined carbon results.
- Principle: Dissolve sample in methanol and nitric acid, treat with hydrofluoric acid, filter non‑combined carbon onto a glass‑fibre filter, combust filter with iron and accelerator in an induction furnace, measure CO2/CO by infrared absorption.
- Reagents & gases: Use analytical‑grade reagents and CO2‑free water (see ISO 3696); oxygen purity ≥ 99.5 % and appropriate purification (desiccants/impregnated traps).
- Apparatus: High‑frequency induction combustion furnace with IR detector (commercial systems available), 47 mm glass‑fibre filters (0.3 µm), ceramic crucibles pre‑ignited to remove carbon, vacuum filtration suitable for acids.
- Calibration: Establish calibration curve using primary product calibration or certified reference materials (CRMs) (cast iron CRMs with 1–3 % carbon, white structure).
- Quality controls: Blank tests (two blanks per run) and instrument stabilization procedures; sampling per ISO 14284; safety precautions for oxygen handling and avoidance of hazardous reagent mixtures.
Applications - who uses this standard
- Foundry and metallurgy laboratories for routine quality control of cast iron grades.
- Materials testing and certification bodies to verify graphitic (non‑combined) carbon content for specification compliance.
- R&D and failure analysis teams evaluating microstructure effects (graphite content vs. mechanical properties).
- Process control in heat treatment and alloying where graphitic/carbidic balances influence machinability, strength and wear properties.
Practical benefits include reproducible measurement of graphitic carbon that affects mechanical behaviour of cast irons and a standardized approach for traceable results through CRM‑based calibration.
Related standards
- ISO 14284 - Sampling and preparation of samples for chemical composition (referenced for sampling).
- ISO 3696 - Water for analytical laboratory use (reagent water quality).
- ISO/TC 17 (committee responsible) and the predecessor ISO/TR 10719:1994 are relevant for historical context.