GB/T 223.60-2024 Iron, steel and alloy - Determination of silicon content - Gravimetric method
WARNING — Persons using this document shall be familiar with normal laboratory practice. This document does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions.
1 Scope
This document specifies a gravimetric method for the determination of the silicon content in iron, steel, high temperature alloys and precision alloys.
This document is applicable to silicon contents between 0.10% (mass fraction) and 6.00% (mass fraction).
Note: For samples containing molybdenum, niobium, tantalum, titanium, tungsten, zirconium or high levels of chromium, the results are less accurate than for unalloyed matrixes.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 6682 Water for analytical laboratory use - Specification and test methods (GB/T 6682-2008, ISO 3696:1987, MOD)
GB/T 20066 Steel and iron - Sampling and preparation of samples for the determination of chemical composition (GB/T 20066-2006, ISO 14284:1996, IDT)
3 Terms and definitions
No terms and definitions are listed in this document.
4 Principle
Dissolution of a test portion with hydrochloric and nitric acids. Conversion of acid-soluble silicon compounds to hydrated silicon dioxide by evaporation with perchloric acid until white fumes appear. Filtration of the hydrated silicon dioxide and acid-insoluble silicon compounds, ignition to form impure silicon dioxide and then weighing. Treatment of the ignited residue with hydrofluoric and sulfuric acids, followed by ignition and weighing. The silicon content is calculated based on the difference of masses weighed before and after silicon removal.
5 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and grade 2 water as specified in GB/T 6682.
5.1 Hydrochloric acid
ρ approximately 1.19 g/mL.
5.2 Hydrochloric acid, 1+1
Obtained by diluting with hydrochloric acid (5.1).
5.3 Hydrochloric acid, 1+19
Obtained by diluting with hydrochloric acid (5.1).
5.4 Nitric acid, 3+1
Obtained by diluting with nitric acid (ρ approximately 1.40 g/mL).
5.5 Hydrofluoric acid
ρ approximately 1.14 g/mL.
5.6 Perchloric acid
ρ approximately 1.67 g/mL.
WARNING - Perchloric acid vapour may cause explosions in the presence of ammonia, nitrous fumes or organic material in general.
Note: Perchloric acid (ρ approximately 1.54 g/mL) can also be used.
5.7 Sulphuric acid, 1+1
Cautiously add 50 mL of sulphuric acid, ρ approximately 1.84 g/mL, to 50 mL of water, allow to cool and mix.
5.8 Methanol
5.9 Ammonium thiocyanate solution
With a concentration of 50 g/L.
Foreword i
Introduction i
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Reagents
6 Apparatus
7 Sampling
8 Analytical procedure
9 Expression of results
10 Test report
Annex A (Informative) Components of GB/T 223
Annex B (Informative) Additional information on the precision test
Annex C (Informative) Graphical representation of precision data
Bibliography
