This standard specifies the method for determining the amount of chromium in chromium and nickel-chromium-iron alloys by ammonium persulfate oxidation. This standard is applicable to the determination of chromium in nickel-chromium and nickel-chromium-iron alloys, with a determination range of 10.00% to 30.00‰. JB/T 6326.2-1992 Chemical analysis method for nickel-chromium and nickel-chromium-iron alloys Determination of chromium content by ammonium persulfate oxidation capacity method JB/T6326.2-1992 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
JB/T6326.2-1992
Chemical analysis method for nickel-chromium and nickel-chromium-iron alloys Determination of chromium content by ammonium persulfate oxidation volumetric method
Published on June 26, 1992
Implementation by the Ministry of Machinery and Electronics Industry of the People's Republic of China on January 1, 1993
Mechanical Industry Standard of the People's Republic of China
Chemical analysis method for nickel-chromium and nickel-chromium-iron alloys Determination of chromium content by ammonium persulfate oxidation volumetric method
Subject content and scope of application
This standard specifies the method for determining chromium content in nickel-chromium and nickel-chromium-iron alloys by ammonium persulfate oxidation volumetric method. JB/T6326.21992
This standard is applicable to the determination of chromium content in nickel-chromium and nickel-chromium-iron alloys, with a determination range of 10.00% to 30.00%. 2 Reference Standards
GB1467 General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products 3 Method Summary
After the sample is dissolved with acid, chromium is oxidized to hexavalent with ammonium persulfate in a sulfuric acid-phosphoric acid medium with silver nitrate as catalyst, and titrated with standard ammonium ferrous carbonate solution.
4 Reagents
4.1 Anhydrous sodium carbonate
Hydrochloric acid (density p1.19g/ml).
Nitric acid (density p1.42g/ml).
Phosphoric acid (density p1.69g/ml).
Hydrochloric acid-nitric acid mixed acid: hydrochloric acid (4.2) + nitric acid (4.3) (1+1). Sulfuric acid (1+1).
Sulfuric acid (5+95). www.bzxz.net
Silver nitrate solution (10g/L).
4.9 Ammonium persulfate solution (200g/L) prepared on the same day. 4.10
Sodium oxide solution (50g/L).
4.11 Phenyl-anthranilic acid indicator solution (2g/L): Weigh 0.2g of phenyl-anthranilic acid and place it in a 150ml beaker, add 0.2g of anhydrous sodium carbonate (4;1), add 2~3ml of water to dissolve, dilute with water to 100ml, and mix well. 4.12 Chromium standard solution: Weigh 5.6578g of standard potassium dichromate (pre-dried at 150C for 1h, placed in a desiccator, and cooled to room temperature) and place it in a 300ml beaker, dissolve with about 200ml of water, transfer to a 1000ml volumetric flask, dilute with water to the mark, and mix well. This solution contains 2.00mg of chromium in 1ml.
4.13 Preparation and calibration of ammonium ferrous sulfate standard solution. 4.13.1 Preparation: Weigh 20g of ammonium ferrous sulfate, dissolve in 1000ml sulfuric acid (4.7), and mix well. Add 5g of pure aluminum (purity greater than 99.9%). 4.13.2 Calibration: Take three 500ml conical flasks. Add 16ml of sulfuric acid (4.6) and 5ml of phosphoric acid (4.4) to each, heat and evaporate until sulfuric acid smoke appears, cool slightly, add 50ml of water, mix well, cool to room temperature, add chromium standard solution (the amount should be close to the chromium content in the sample), dilute with water to 200ml, titrate with ammonium ferrous sulfate standard solution (4.13.1) until the solution turns light yellow, add 3 drops of phenyl anthranilic acid solution (4.11), and continue titrating until the color changes from red to bright green as the end point. Read the number of milliliters of ammonium ferrous sulfate standard solution consumed. Three portions of chromium standard solution approved by the Ministry of Machinery and Electronics Industry on June 26, 1992 and implemented on January 1, 1993
JB/T6326.21992
The extreme value of the number of liters of ammonium ferrous sulfate standard solution consumed should not exceed 0.05ml, and the average value is taken. Calculate the titer of ammonium ferrous sulfate standard solution on chromium vc according to the following formula
Wherein, T-
The titer of ammonium ferrous sulfate standard solution on chromium, g/ml: the concentration of chromium standard solution, g/ml;
VThe volume of chromium standard solution transferred, ml;
V, the average volume of ammonium ferrous sulfate standard solution consumed in titration, ml. 5 Analysis steps
5.1 Sample quantity
Weigh 0.2000g of sample.
5.2 Determination
5.2.1 Place the sample in a 500ml conical flask, add 10~20ml hydrochloric acid and nitric acid mixture (4.5) to dissolve at low temperature, add 16ml sulfuric acid (4.6) and 5ml phosphoric acid (4.4), heat until sulfuric acid smoke appears, remove and cool slightly. 5.2.2 Add 200ml hot water, then add 5ml silver nitrate solution (4.8) and 20ml ammonium persulfate solution (4.9), mix well, heat and boil until the solution turns red, and continue to boil for 5 minutes to decompose the ammonium persulfate completely. Add 10 ml of sodium chloride solution (4.10), boil until the red color disappears, and continue to boil for 8-10 minutes to make the silver chloride precipitate condense and the solution clear. 5.2.3 Cool to room temperature, titrate with ammonium ferrous sulfate standard solution (4.13.1) until the solution turns light yellow, add 3 drops of phenyl anthranilic acid indicator solution (4.11), and continue to titrate until the solution changes from rose red to bright green as the end point. Calculation of analysis results
Calculate the percentage of chromium according to the following formula:
Cr(%):
Where: V,-volume of ammonium ferrous sulfate standard solution consumed by the titration sample, ml; T--titration degree of ferrous sulfate on chromium by standard solution, g/ml; (2)
mSample volume, g.
Note: If the alloy contains zirconium, 1.0% zirconium is equivalent to 0.12% chromium for correction. If vanadium is contained, correction shall be made based on 1.0% vanadium being equivalent to 0.34% chromium. Allowable difference
The difference in analysis results between laboratories shall not be greater than the allowable difference listed in the following table. Table
Chromium content
10.00~18.00
>18.00~30.00
Additional notes:
This standard was proposed and coordinated by the Shanghai Electric Science Research Institute of the Ministry of Machinery and Electronics Industry. This standard was drafted by Sichuan Instrument Factory No. 1, and the main drafters of this standard were Li Zhengrong and Fan Chunzhen. 2
Filling allowable difference
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