GB/T 33948.2-2017Method for chemical analysis of copper-steel composite metal—Part 2: Determination of zinc content—Na2EDTA titration method (English PDF)
铜-钢复合金属化学分析方法 第2部分：锌含量的测定 Na2EDTA滴定法
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Issued by
SAMR; SAC
Level / Type
National · Recommended
Issue date
July 12, 2017
Implementation date
February 1, 2018
Scope
GB/T 33948.2-2017 is the English-translated version of 铜-钢复合金属化学分析方法 第2部分：锌含量的测定 Na2EDTA滴定法.
GB/T 33948.2-2017 is Part 2 of the GB/T 33948 series on methods for the chemical analysis of copper-steel composite metal, and this record is served with the official English translation.
It gives the determination of zinc content by the Na2EDTA titration method, for a determination range from above 0.50 % to 6.50 %.
In the method the test material is dissolved in hydrochloric acid, zinc and thiocyanate form a complex anion in dilute hydrochloric acid medium, most of the interfering elements are removed by extraction with 4-methyl-2-pentanone, and the zinc is then titrated with Na2EDTA standard titration solution in a hexamethylenetetramine buffer at pH 5.5 to 6.0, with a masking agent added and xylenol orange as indicator, until the solution turns from red to yellow; the zinc is calculated from the volume of Na2EDTA consumed.
The standard lists the reagents, the preparation and parallel calibration of the Na2EDTA solution, the preparation of the specimen from composite metal above and below 0.7 mm in thickness, the analysis steps with a 0.200 g test portion weighed to the nearest 0.0001 g, two independent determinations and a blank test, the calculation of results, the precision and the test report. It was issued on 12 July 2017 and has applied since 1 February 2018.
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Document preview — GB/T 33948.2-2017
National Standard of the People's Republic of China
- ICS
- 77.120.30
- Classification
- H 13
Issued by: State Administration for Market Regulation; Standardization Administration of the PRC
Contents
- Foreword3
- 1 Scope4
- 2 Method summary4
- 3 Reagents4
- 4 Specimen6
- 5 Analysis steps6
- 6 Calculation of analysis results7
- 7 Precision8
- 8 Test report8
1 Scope
This Part of GB/T 33948 specifies the determination method of zinc content of copper-steel composite metal.
This Part applies to the determination of zinc content of copper-steel composite metal. The determination range is >0.50% ~ 6.50%.
2 Method summary
The test material is dissolved in hydrochloric acid. Zinc and thiocyanate form a complex anion in dilute hydrochloric acid medium. After extracting and removing most of the interference elements with 4-methyl-2-pentanone extraction, in hexamethyltetramine buffer solution with a pH of 5.5-6.0, add concealer to xylenol orange as indicator, titrate with Na2EDTA standard titration solution until the solution turns from red to yellow. Calculate the amount of zinc based on the volume of Na2EDTA standard solution consumed.
3 Reagents
Unless otherwise stated, only analytically pure reagents and distilled or deionized water or equivalent water are used in the analysis.
3.1 4-methyl-2-pentanone.
3.2 Hydrogen peroxide (rho=1.11 g/mL).
3.3 Hydrochloric acid (1+1).
3.4 Nitric acid (1+1).
3.5 Ammonium fluoride solution (200 g/L), stored in plastic bottle.
3.6 Thiourea Solution (100 g/L).
3.7 Ammonium thiocyanate solution (500 g/L)
V0 - the volume of Na2EDTA titration solution consumed when titrating a blank solution, in milliliters (mL);
63.55 - mole mass of zinc, in grams per mole (g/mol).
3.12.3 Parallel calibration
Perform 3 copies of parallel calibration. The standard volume of Na2EDTA standard titration solution used for calibration is not more than 0.10 mL. Take its average value, otherwise, recalibrate.
4 Specimen
4.1 Wipe clean the surface of the copper-steel composite metal specimen with acetone of thickness less than or equal to 0.7 mm, without oxidation, oil stain.
Then make the sample into pieces with a width of no more than 1mm. And ensure that the coating metal is consistent when preparing double-sided (or single-sided) composite specimen.
4.2 Copper-steel composite metal sample with a thickness greater than 0.7 mm is first made into thin strips with a width of 1 mm. And wipe it clean with acetone, without oxidation, oil stain. Then make it to pieces less than 1 mm in width. And ensure that the coating metal is consistent when preparing double-sided (or single-sided) composite specimen.
5 Analysis steps
5.1 Test material
Weigh 0.200 g of specimen (Clause 4), to the nearest of 0.0001 g.
5.2 Number of determinations
Perform two determinations independently. Take the average value.
5.3 Blank test
Perform the blank test with test materials.
5.4 Determination
5.4.1 Place the test material (5.1) in a 500-mL conical beaker. Add 10 mL of hydrochloric acid (3.3). Drop hydrogen peroxide 4 times (3.2), 2 mL for each (shake for a moment for each adding). Dissolve at low temperature until the sample dissolves completely (solution is transparent without impurities). Cover the watch glass, boil, remove excessive hydrogen peroxide, cool. If the […]
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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.
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