ISO 14720-1:2013

Overview

ISO 14720-1:2013 specifies an infrared measurement method for the determination of sulfur in powdered and granular non-oxidic ceramic raw and basic materials. Typical materials covered include silicon carbide, silicon nitride, graphites, carbon blacks, cokes and other carbon powders. The method is applicable for sulfur mass fractions from 0.005% to 2% and can be extended to higher concentrations after verification. The procedure releases total sulfur as SO2 by high-temperature combustion and quantifies SO2 by infrared absorption.

Key topics and technical requirements

• Principle: Combustion of sample in an oxygen atmosphere (inductive or resistance furnace) at temperatures above 1 800 °C produces SO2, which is measured by an infrared analyser using a narrow-band optical filter.
• Scope & limits: Applicable to non-oxidic ceramic powders/granules; validated range 0.005%–2% S (extensions require verification).
• Apparatus & precision:
  • Induction furnace (or resistance furnace alternative) with infrared cell.
  • Analytical balance with 0.01 mg readability.
  • Ceramic crucibles and lids (mullite/alumina).
• Reagents & gases:
  • Tungsten and/or iron granules as combustion accelerators (tungsten/tin mixtures noted).
  • Oxygen purity ≥ 99.998% (V/V).
  • Calibration standards: preferably matrix-analogous Certified Reference Materials (CRMs) or sulfates.
• Sample preparation:
  • Representative sampling (e.g., per ISO 8656-1).
  • Dry to constant mass at 110 ± 5 °C; particle size ≤ 160 µm.
  • Typical test sample masses 20–200 mg depending on expected sulfur content.
• Calibration & quality control:
  • Calibrate using calibration standards of similar sulfur mass.
  • Verify trueness for low concentrations (