GB/T 13748.18-2026Methods for chemical analysis of magnesium and magnesium alloys - Part 18: Determination of chlorine content - Silver chloride turbidimetric method (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part

1.Structure and Drafting Rules of Standardization Documents". Drafting. This document is Part 18 of GB/T 13748, "Chemical Analysis Methods for Magnesium and Magnesium Alloys". GB/T 13748 has published the following... part.

1.Determination of Aluminum Content;

2.Determination of Tin, Beryllium, Copper, Nickel and Titanium Content by Spectrophotometry;

3.Determination of Lithium and Silver Content by Flame Atomic Absorption Spectrometry;

4.Determination of Manganese and Zirconium Content by Spectrophotometry;

8.Determination of Rare Earth Content;

9.Determination of Iron and Silicon Content by Spectrophotometry;

13.Determination of Lead, Calcium, Potassium and Sodium Content by Flame Atomic Absorption Spectrometry;

15.Determination of Zinc Content;

18.Determination of Chlorine Content using the Silver Chloride Turbidity Method;

20.Determination of Elemental Content by Inductively Coupled Plasma Atomic Emission Spectrometry;

21.Determination of Elemental Content by Direct-Reading Atomic Emission Spectrometry;

22.Determination of Thorium Content;

8 Test Procedure

8.1 Samples Weigh the sample according to Table 1 (Chapter 7), accurate to 0.0001g, and record it as m0.

8.2 Parallel Tests Perform the experiment twice in parallel and take the average value.

8.3 Blank Test A blank test was performed along with the sample.

10 Precision

10.1 Repeatability The measured values of two independent test results obtained under repeatability conditions, within the range of the average values given in Table 2, represent the two test results. The absolute difference does not exceed the repeatability limit (r), and the number of cases exceeding the repeatability limit (r) does not exceed 5%. The repeatability limit (r) is determined by linearity based on the data in Table 2. Obtained by interpolation or extrapolation.

10.2 Reproducibility The measured values of two independent test results obtained under reproducibility conditions, within the range of the average values given in Table 3, represent the two test results. The absolute difference should not exceed the reproducibility limit (R), and the number of cases exceeding the reproducibility limit (R) should not exceed 5%. The reproducibility limit (R) is calculated using linear regression based on the data in Table 3. It can be obtained by interpolation or extension.

11 Test Report The test report should include at least the following.

---Test subjects;

---Document number;

---Analysis results and their representation;

---Differences from basic analytical procedures;

---Observed anomalies;

18 Determination of Chlorine Content Silver chloride turbidimetric method

1.Scope This document describes a method for determining the chlorine content in magnesium and magnesium alloys using the silver chloride turbidity method. This document applies to the determination of chlorine content in magnesium and magnesium alloys. Determination range (mass fraction). 0.0010%~0.10%.

3.Terms and Definitions This document does not contain any terms or definitions that need to be defined.

4.Method Overview The sample was dissolved in sulfuric acid. In the presence of acetone, chlorine reacted with silver nitrate to form a silver chloride emulsion. The solution was measured at a spectrophotometer at a wavelength of 420 nm. Measure its absorbance, find the mass of chlorine according to the working curve, and calculate the mass fraction of chlorine.

5.Reagents or materials Unless otherwise specified, only reagents confirmed to be of analytical grade and grade II water conforming to GB/T 6682 shall be used in the analysis.

5.1 Nitric acid (rho=1.42g/mL).

5.3 Sulfuric acid (1 3).

5.4 Silver nitrate solution (10 g/L). Store in a brown glass bottle away from light.

5.5 Chlorine Standard Stock Solution (1 mg/mL). Weigh 1.6485 g of sodium chloride (pre-calculated at 400°C~500°C to constant weight, without explosion). The crackling sound (after cooling to room temperature in a desiccator) is dissolved in water, transferred to a 1000 mL volumetric flask, diluted to the mark with water, and mixed well. This solution... 1 mL contains 1 mg of chlorine.