GB/T 4702.16-2025 Chromium metal—Determination of sulfur content—Infrared absorption method and combustion-neutralization titration method English, Anglais, Englisch, Inglés, えいご
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ICS 77. 100 CCS H 11
National Standard of the People's Republic of China
GB/T 4702.16-2025
Replaces GB/T 4702.16-2008
Chromium Metal—Determination of Sulfur Content—Infrared Absorption Method and Combustion-Neutralization Titration Method
Issued on 2025-08-29
Implemented on 2026-03-01
State Administration for Market Regulation
Standardization Administration of China
Table of Contents
Scope
Normative References
Terms and Definitions
Method 1: Infrared Absorption Method
Method 2: Combustion-Neutralization Titration Method
Test Report
Appendix A (Normative) Flowchart for Sample Analysis Result Acceptance
Warning
Users of this document should have formal laboratory working experience. This document does not address all possible safety issues. Users are responsible for taking appropriate safety and health measures and ensuring compliance with national regulations.
1. Scope
This document specifies two methods for determining sulfur content in chromium metal:
Infrared absorption method: Applicable range (mass fraction) 0.0005%–0.045%.
Combustion-neutralization titration method: Applicable range (mass fraction) 0.005%–0.070%.
2. Normative References
Essential provisions are derived from:
GB/T 4010: Sampling and preparation of samples for chemical analysis of ferroalloys.
GB/T 6379.1–3: Accuracy (trueness and precision) of measurement methods and results.
GB/T 6682: Specifications and test methods for water used in analytical laboratories.
GB/T 8170: Rules for rounding off numerical values and expression and judgement of limiting values.
3. Terms and Definitions
No special terms require definition.
4. Method 1: Infrared Absorption Method
4.1 Principle
The sample is combusted in an oxygen stream within a high-frequency induction furnace. Generated sulfur dioxide (SO₂) is carried to the measurement cell of an infrared analyzer. SO₂ absorbs infrared energy at a specific wavelength, with absorption proportional to its concentration. Sulfur content is determined by detecting energy changes.
4.2 Reagents and Materials
4.2.1 Anhydrous magnesium perchlorate (granular).
4.2.2 Ascarite (granular).
4.2.3 Glass wool.
4.2.4 Tungsten granules (S < 0.0005%, particle size 0.8–1.4 mm).
4.2.5 Tin granules (S < 0.0005%, particle size 0.4–0.8 mm).
4.2.6 Tungsten-tin flux (S < 0.0005%; for samples with S < 0.001%, S < 0.0002%).
4.2.7 Pure iron (S < 0.0005%, particle size 0.8–1.68 mm; purity >99.99% for samples with S < 0.001%).
4.2.8 Oxygen (purity >99.95%; lower grades acceptable if blanks are consistently low).
4.2.9 Carrier gas (nitrogen, argon, or compressed air; impurities <0.5%).
4.2.10 Ceramic crucibles (preheated at 1,200°C for 4 h or until minimal blanks; stored desiccated; used within 24 h for low-sulfur samples).
4.3 Apparatus
4.3.1 High-frequency combustion infrared carbon-sulfur analyzer or infrared absorption sulfur analyzer (sensitivity 1.0×10⁻⁶; for S < 0.001%, repeatability ≤0.0002%).
4.3.1.1 Includes scrubber bottles (filled with ascarite, 4.2.2) and drying tubes (filled with magnesium perchlorate, 4.2.1).
