GB/T 223.63-2022Iron, steel and alloy - Determination of manganese content - Sodium (potassium) periodate spectrophotometric method (English PDF)

5.1 Hydrofluoric Acid

rho is about 1.15 g/mL.

5.2 Hydrochloric Acid

rho is about 1.19 g/mL.

5.3 Nitric Acid

rho is about 1.42 g/mL.

5.4 Nitric Acid, 1 + 4

Dilute with nitric acid (5.3).

5.5 Sulfuric Acid, 1 + 1

Dilute with sulfuric acid with rho about 1.84 g/mL.

5.6 Perchloric Acid, 1 + 499

Dilute with perchloric acid with rho about 1.67 g/mL.

5.7 Phosphoric Acid - Perchloric Acid Mixed Acid

Mix three portions of phosphoric acid (rho about 1.69 g/mL) and one portion of perchloric acid (rho about 1.67 g/mL).

5.8 Sodium (potassium) Periodate Solution, 50 g/L

Weigh-take 5 g of sodium periodate or potassium periodate and place in a 250 mL beaker; add

60 mL of water and 20 mL of nitric acid (see 5.3), warm to dissolve it, then, cool it. Use water to dilute to 100 mL and mix it well.

5.9 Sodium Nitrite Solution, 10 g/L

Weigh-take 1 g of sodium nitrite, place in a 250 mL beaker, add 60 mL of water to dissolve it, then, use water to dilute to 100 mL and mix it well.

5.10 Manganese Standard Solution

5.10.1 Manganese standard solution, 500 g/mL

Weigh-take 1.4383 g of potassium permanganate (mass fraction not less than 99.9%) and place in a 600 mL beaker; add 300 mL of water to dissolve it, add 10 mL of sulfuric acid (see 5.5)

and dropwise add hydrogen peroxide (rho about 1.10 g/mL), until the red color just disappears;

heat to boil for 5 min ~ 10 min, then, cool it. Transfer it to a 1,000 mL volumetric flask; use water to dilute to the mark and mix it well.

Alternatively, weigh-take 0.5000 g of electrolytic manganese (mass fraction not less than 99.9%)

[electrolytic manganese needs to be cleaned in sulfuric acid (5 + 95) in advance, and after manganese oxide on the surface is cleaned, take it out, immediately use distilled water to repeatedly wash it, then, wash it in absolute ethanol for 4 ~ 5 times, take it out and dry it in a desiccator before use] and place in a 250 mL beaker; add 20 mL of nitric acid (1 + 3), heat to dissolve it and boil to drive out nitrogen oxides; remove and cool it to room temperature. Then, transfer to a 1,000 mL volumetric flask, use water to dilute to the mark and mix it well.

1 mL of this standard solution contains 500 g of manganese.

5.10.2 Manganese standard solution, 100 g/mL

Weigh-take 20.0 mL of manganese standard solution (see 5.10.1) and place in a 100 mL volumetric flask; use water to dilute to the mark and mix it well.

1 mL of this standard solution contains 100 g of manganese.

5.10.3 Manganese standard solution, 20 g/mL

Weigh-take 20.0 mL of manganese standard solution (see 5.10.2) and place in a 100 mL volumetric flask; use water to dilute to the mark and mix it well.

1 mL of this standard solution contains 20 g of manganese.

5.11 Water without Reducing Substances

Heat distilled water or deionized water to boil, use 10 mL of sulfuric acid (1 + 3) to acidify each liter; add a few granules of sodium (potassium) periodate and continue to boil for 1 min ~ 2 min, cool it before use.

reaction stops. Add 1 mL ~ 2 mL of hydrochloric acid (see 5.2), and continue heating, until it is completely decomposed.

---For high-nickel-chromium specimens, add 10 mL of (3 + 1), (6 + 1) or (10 + 1) mixed acid of hydrochloric acid (see 5.2) and nitric acid (see 5.3), heat at low temperature to dissolve it.

NOTE: when the amount of specimen is 2 g, depending on the situation, the amount of acid can be increased, so that the specimen can be completely dissolved.

Add 10 mL of phosphoric acid - perchloric acid mixed acid (see 5.7) [when the amount of specimen is 2.0 g, add 15 mL of phosphoric acid - perchloric acid mixed acid (see 5.7); when using 15 mL of phosphoric acid - perchloric acid mixed acid (see 5.7) to dissolve high-tungsten specimens, it is not necessary to add], heat and evaporate it, until perchloric acid fumes are emitted for 2 min ~ 5 min (for specimens with high chromium content, the chromium needs to be oxidized); slightly cool and add water to dissolve salts. If necessary, remove graphitic carbon by filtration and use hot perchloric acid (see 5.6) to wash it.

---When the manganese content is not greater than 2.00%, add 10 mL of sulfuric acid (see 5.5) and use water to dilute to about 40 mL.

---When the manganese content is greater than 2.00%, add 10 mL of sulfuric acid (see 5.5)

and use water to dilute to about 40 mL; cool to room temperature, then, transfer to a 100 mL volumetric flask; use water to dilute to the mark and mix it well. Transfer-take

50.0 mL of test solution in a 150 mL conical flask, additionally add 5 mL of sulfuric acid (see 5.5).

8.2.2 Color development In the test solution prepared in 8.2.1, add 10 mL of sodium (potassium) periodate solution (see 5.8), heat to boil and maintain it for 2 min ~ 3 min (to prevent the test solution from splashing out); cool to room temperature and transfer to a 100 mL volumetric flask; use water without reducing substances (see 5.11) to dilute it to the mark and mix it well.

8.2.3 Preparation of reference solution Transfer-take about 25 mL of chromogenic solution (see 8.2.2) to a 100 mL conical flask; while shaking it, dropwise add sodium nitrite solution (see 5.9), until the purple color just fades (see

NOTE). Use this solution as the reference solution.

NOTE: when the cobalt-containing specimen is faded with sodium nitrite solution, the reddish color of cobalt will not fade, and it can be handled in accordance with the following method:

constantly shake the volumetric flask, slowly and dropwise add sodium nitrite solution (see 5.9), if the reddish color of the specimen remains unchanged, put the solution in an absorption vessel and measure its absorbance; add sodium nitrite solution (see 5.9) to the remaining test solution, then, measure the absorbance again, until there is no change in the absorbance.

9 Processing of Test Data Utilize the calibration curve (see 8.2.5.2) to convert the absorbance to the mass of manganese in the corresponding test solution, expressed in g.

The manganese content (wMn), which is expressed in mass fraction (%), shall be calculated in accordance with Formula (1):

Where, m1---the mass of manganese obtained from the calibration curve, expressed in (g);

m---the amount of specimen, expressed in (g);

V---the total volume of the test solution, expressed in (mL);

V1---the volume of the divided test solution, expressed in (mL).

10 Precision The precision test in this document was performed by 10 laboratories on 10 levels of manganese content. Each laboratory determines each level of manganese content twice under the repeatability conditions specified in GB/T 6379.1.

See Table B.1 of Appendix B for the specimens used. See Table B.2 of Appendix B for the original data of the precision test.

In accordance with GB/T 6379.2, conduct statistical analysis on the obtained results. The results suggest that there is a logarithmic relation between the manganese content and the repeatability limit (r) and reproducibility limit (R) of the test results, which are summarized in Table 3.

The repeatability limit (r) and reproducibility limit (R) are obtained through the equation provided in Table 3.

Under repeatability conditions, the absolute difference of the obtained two independent