GB/T 16477.2-2026Chemical analysis methods for rare earth ferrosilicon and rare earth magnesium ferrosilicon alloys - Part 2: Determination of calcium, magnesium, manganese, aluminium, barium, antimony, bismuth, strontium, phosphorus and titanium contents (English PDF)

4.2.19 Mixed Standard Solution. Transfer

10.00 mL of calcium standard stock solution (4.2.9) and

10.00 mL of manganese standard stock solution (4.2.11).

10.00 mL aluminum standard stock solution (4.2.12),

10.00 mL barium standard stock solution (4.2.13),

10.00 mL antimony standard stock solution (4.2.14),

10.00 mL of bismuth standard stock solution (4.2.15), and

10.00 mL of strontium standard stock solution (4.2.16) are placed in a 100 mL volumetric flask. Add 5 mL of hydrochloric acid (4.2.1) and dilute to the mark with water. 1 mL of this solution contains 100 µg calcium, 100 µg manganese, 100 µg aluminum, and 100 µg... Barium, 100 µg antimony, 100 µg bismuth, 100 µg strontium.

4.2.20 Magnesium Standard Solution. Transfer

10.00 mL of magnesium standard stock solution (4.2.10) to a 100 mL volumetric flask, add 5 mL of hydrochloric acid. (4.2.1) Dilute with water to the mark. 1 mL of this solution contains 100 µg of magnesium.

4.2.21 Phosphorus Standard Solution. Transfer

10.00 mL of the phosphorus standard stock solution (4.2.17) to a 100 mL volumetric flask and dilute to the mark with water. One mL of the solution contains 100 µg of phosphorus.

4.2.22 Titanium Standard Solution. Transfer

10.00 mL of titanium standard stock solution (4.2.18) to a 100 mL volumetric flask, add 2 mL of sulfuric acid. (4.2.8) Dilute with water to the mark. 1 mL of this solution contains 100 µg of titanium.

4.3 Instruments and Equipment The inductively coupled plasma atomic emission spectrometer achieves the following specifications under optimal instrument operating conditions.

---Complies with JJG768;

---The recommended analytical spectral wavelengths for element determination are shown in Table 2.

4.4 Samples The alloy sample was made into a powder and passed through a 0.125mm sieve.

4.5 Test Procedure

4.5.1 Sample Weigh 0.10g of sample (4.4), accurate to 0.0001g.

4.5.2 Parallel Tests Perform two parallel experiments.

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

4.5.4 Preparation of analytical solutions

4.5.4.1 Place the sample (4.5.1) in a.200 mL dry polytetrafluoroethylene beaker, add 5 mL of nitric acid (4.2.2), and slowly add 2 mL of nitric acid dropwise. After the hydrofluoric acid (4.2.3) reaction stops violently, heat at a low temperature until the sample is completely decomposed. Add 3 mL of perchloric acid (4.2.4) and heat at a low temperature until fumes are produced. Continue heating until the test solution is clear (approximately 3-4 mL remaining), remove from heat, allow to cool slightly, add 5 mL of hydrochloric acid (4.2.1), heat to dissolve the salts, and cool to room temperature. Transfer the solution to a 100mL volumetric flask, dilute with water to the mark, and mix well.

4.5.4.2 According to the content range of the element to be tested, accurately aliquot the test solution (4.5.4.1) into a 50mL volumetric flask according to Table 3, and add 10mL of hydrochloric acid. (4.2.5) Dilute with water to the mark and mix well.

4.5.5 Preparation of a series of standard solutions

4.5.5.1 Series of Standard Solutions I Transfer 0 mL,

0.10 mL,

0.50 mL,

10.00 mL of the mixed standard solution, respectively. (4.2.19) and 0 mL,

0.10 mL,

0.50 mL,

30.00 mL magnesium standard solutions (4.2.20) were prepared in the same manner. Add 8 mL of hydrochloric acid (4.2.5) to a set of 100 mL volumetric flasks, dilute to the mark with water, and mix well. The mass concentration of series standard solution I is... See Table 4.

4.5.5.2 Series of Standard Solutions II Transfer 0 mL,

0.10 mL,

0.50 mL,

10.00 mL of phosphorus standard solution (4.2.21) respectively. Add 8 mL of hydrochloric acid (4.2.5) to a set of 100 mL volumetric flasks, dilute to the mark with water, and mix well. The mass of phosphorus in series standard solution II... The concentrations were 0 µg/mL, 0.10 µg/mL, 0.50 µg/mL, 1.00 µg/mL, 2.50 µg/mL, and 5.00 µg/mL, respectively. 10.00 µg/mL.

4.5.5.3 Series of Standard Solutions III Transfer 0 mL,

0.10 mL,

0.50 mL,

4.5.6 Measurement

4.5.6.1 Drawing the working curve Under the selected instrument operating conditions, the series of standard solutions (4.5.5.1~4.5.5.3) were subjected to argon plasma optical emission testing using the recommended analytical lines. Spectroscopic determination. A working curve was plotted with the optical signal intensity of the analyte as the ordinate and the mass concentration of a series of standard solutions as the abscissa, and linear correlation was established. The coefficient should be no less than 0.9995.

4.5.6.2 Determination of blank test solution After the working curve (4.5.6.1) meets the determination requirements, perform argon plasma spectroscopy on the blank test solution (4.5.3) using the recommended analytical lines. Measurement. The instrument automatically processes the data according to the working curve, calculates and outputs the mass concentration of the element to be measured in the blank test solution.

4.5.6.3 Determination of analytical solutions After the working curve (4.5.6.1) meets the determination requirements, the analytical solution (4.5.4.2) is subjected to argon plasma optical emission testing using the recommended analytical lines. Spectroscopic determination. The instrument automatically processes data based on the working curve, calculates and outputs the mass concentration of the analyte in the analytical solution.

Note. When using an instrument with an online internal standard solution addition device, the measurement results are calibrated in real time by monitoring the signal intensity change of the internal standard element (such as scandium). This is to compensate for the effects of instrument fluctuations and changes in sample introduction efficiency.

4.7 Precision

4.7.1 Repeatability Under repeatability conditions, the absolute difference between two independent test results does not exceed the repeatability limit (r); otherwise, the result is considered acceptable. The repeatability limit (r) is determined by linear interpolation or extrapolation based on the data in Table 5, provided that the limit is no more than 5%.

5.4 Test Procedure

5.4.1 Sample Weigh 0.30g of sample (5.3), accurate to 0.0001g.

5.4.2 Parallel Tests Perform two parallel experiments.

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

5.4.4 Preparation of analytical solutions

5.4.4.1 Place the sample (5.4.1) in a.200 mL dry polytetrafluoroethylene beaker, add 10 mL of nitric acid (5.2.4), and add dropwise while shaking. After the vigorous reaction stops with 5 mL of hydrofluoric acid (5.2.5), dissolve the sample by heating at low temperature, then add 5 mL of perchloric acid (5.2.6) and heat on a low-temperature electric furnace. Heat until perchloric acid fumes are produced and evaporate to near dryness. Remove from heat, allow to cool slightly, and add 5 mL of hydrochloric acid (5.2.3) to dissolve the sample. Remove from heat and cool the solution. Transfer to... Dilute to the mark with water in a 100mL volumetric flask and mix well.

5.4.4.2 If the content of barium and strontium in the sample (5.4.1) is greater than 0.20%, add 10 mL of hydrochloric acid to the solution dissolved in 5.4.4.1. Sulfuric acid (5.2.10), heated to boiling, then cooled to room temperature. Transfer to a 100 mL volumetric flask, dilute to the mark with water, and mix well. Let stand. After 10 minutes, slow quantitative filter paper dry filtration was performed.

5.4.4.3 According to Table 7, transfer two portions of the test solution (

5.4.4.1 or 5.4.4.2) into two 250mL beakers, and label them as solution A and solution B. After procedures

5.4.4.4 and 5.4.4.5, one sample is titrated for the combined calcium and magnesium content, and the other sample is titrated for the calcium content.

5.4.4.4 If the aluminum content in the sample (5.4.1) is greater than 1.0%, add water to the test solution (5.4.4.3) to 100 mL, and then add sodium hydroxide solution dropwise. (5.2.12) Continue heating until a precipitate forms, with an excess of 3 mL. Boil for 1 min, filter with medium-speed quantitative filter paper, and wash with hot sodium hydroxide solution. (5.2.13) Wash the beaker 3 times, and precipitate 7-8 times. Return the precipitate and filter paper to the original beaker, and add 15 mL of nitric acid (5.2.4). Add 5 mL of perchloric acid (5.2.6), cover with a watch glass, heat to dissolve the precipitate and break the filter paper, and produce perchloric acid fumes until the volume reaches approximately 1 mL. Remove and cool. However, add 1 mL of hydrochloric acid (5.2.9) and rinse the watch glass and beaker walls with water. If the aluminum content in the sample (5.4.1) is less than 1.0%, this step is not required. Step-by-step operation.

5.4.4.5 Add water to the test solution (5.4.4.4) to a final volume of 80 mL, add 2 g of ammonium chloride (5.2.1), heat to dissolve the ammonium chloride, and then add ammonia water (5.2.11) to a final volume. When a precipitate forms, add 1 mL of hydrogen peroxide (5.2.7) and an excess of 15 mL of ammonia (5.2.11), heat rapidly to boiling, remove from heat, and add 5 mL of ammonia. Water (5.2.11). Filter the solution into a 400 mL beaker using medium-speed quantitative filter paper. Wash the beaker three times with hot ammonium chloride washing solution (5.2.14). The precipitate... Repeat 7 to 8 times, controlling the filtrate volume to 150 mL to 175 mL, and discard the precipitate.

5.4.5.1 Titration of the combined calcium and magnesium content. Add

0.5 g hydroxylamine hydrochloride (5.2.2) and 10 mL triethanolamine (5.2.15) to solution A (5.4.4). 10 mL of ammonia buffer solution (5.2.17), approximately

0.05 g of Chrome Black T indicator (5.2.24), titrated with EDTA standard titration solution (5.2.20). The titration endpoint is reached when the solution changes from wine red to blue; record the titration volume (V8).

5.4.5.2 Titration of calcium content. Add

0.5 g hydroxylamine hydrochloride (5.2.2), 10 mL triethanolamine (5.2.15), and 20 mL hydrogen to solution B (5.4.4). Potassium oxide solution (5.2.16), approximately

0.05 g of calcium carboxylic acid indicator (5.2.23), titrated with EDTA standard titration solution (5.2.20), the solution was distilled from purple... The endpoint is reached when the red color turns blue; record the titration volume (V10). Calculate the magnesium content using the difference method.

5.6 Precision

5.6.1 Repeatability The absolute difference between two independent test results obtained under repeatability conditions should not exceed the repeatability limit (r). If the absolute difference exceeds the repeatability limit (r), the result is invalid. For cases not exceeding 5%, the repeatability limit (r) is obtained using linear interpolation or extrapolation based on the data in Table 8.

5.6.2 Reproducibility The absolute difference between two independent test results obtained under reproducibility conditions should not exceed the reproducibility limit (R). A difference exceeding the reproducibility limit (R) is considered invalid. For cases where the reproducibility limit (R) is less than 5%, the reproducibility limit (R) is obtained using linear interpolation or extrapolation based on the data in Table 9.