ISO 21079-3:2008

Overview

ISO 21079-3:2008 specifies instrumental analytical methods - flame atomic absorption spectrophotometry (FAAS) and inductively coupled plasma atomic emission spectrometry (ICP‑AES / ICP‑AES) - for chemical analysis of AZS refractories (alumina–zirconia–silica) and associated raw materials containing 5 % to 45 % ZrO2. This part provides an alternative to X‑ray fluorescence (XRF, ISO 12677) and is not applicable to MgO‑based refractories. The standard focuses on procedures for sample preparation (linked to Part 1), calibration, blanking, measurement and calculation of oxide mass fractions.

Key topics and technical requirements

• Analytical methods covered: ICP‑AES for multi‑element emission analysis and FAAS for alkali/alkaline-earth and chromium determinations.
• Measured components: SiO2, Al2O3, Fe2O3, TiO2, CaO, MgO, Na2O, K2O, Cr2O3, HfO2 (with specified application ranges).
  • Example ICP‑AES application ranges: SiO2 (0.1–10 %), Al2O3 (1–10 %), Fe2O3 (0.01–2 %), TiO2 (0.01–5 %), Cr2O3 (0.01–3 %), HfO2 (0.01–2 %).
• Sample solutions / stock solutions: Methods refer to stock solutions (S1, S’1, S’’1, S4) produced according to ISO 21079‑1 (apparatus, reagents, dissolution). Note: SiO2 can be residual silica or total SiO2 depending on which stock solution is used.
• Calibration and internal standards: Matrix‑matched calibration series (series 2/3/4) and use of internal standards (e.g., scandium or yttrium) are specified to ensure accuracy.
• Procedural elements: preparation of calibration series, blank tests, emission/absorption measurements at example wavelengths (e.g., Si 251.611 nm), and calculation of oxide mass fractions using the prescribed equations and dilution factors.
• Reporting: Test report content and calculation steps are defined to support traceable, reproducible results.

Practical applications

• Quality control and incoming raw‑material inspection for AZS refractory manufacturers
• Routine analysis in metallurgical and materials testing laboratories
• Alternative or complementary method to XRF when wet‑chemical instrumental techniques are preferred or required
• Research and development work involving compositional verification of AZS products

Who should use this standard

• Refractory manufacturers and product development teams
• Industrial QA/QC and analytical laboratories performing refractory chemical analysis
• Accredited testing bodies and conformity assessment organizations
• Materials scientists and process engineers in steel, cement and high‑temperature industries

Related standards

• ISO 21079‑1:2008 - Apparatus, reagents and dissolution (sample prep referenced)
• ISO 21079‑2:2008 - Wet chemical analysis
• ISO 12677 - XRF method for refractories (alternative method)
• ISO 26845 - General requirements for wet chemical, AAS and ICP methods

Keywords: ISO 21079‑3, FAAS, ICP‑AES, AZS refractory analysis, alumina zirconia silica, ZrO2, refractory chemical analysis, XRF alternative, refractory QC.