This standard is applicable to the determination of chromium content in nickel-based alloy powder. Determination range: 2.00% to 30.00%. This standard complies with GB 1467-1989 "General Principles and General Provisions for Chemical Analysis Methods for Metallurgical Products". GB/T 8638.4-1988 Chemical analysis method for nickel-based alloy powder Determination of chromium content by ammonium persulfate oxidation titration GB/T8638.4-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis method for nickel-based alloy powder Www.bzxZ.net
Determination of chromium content by ammonium persulfate oxidation titrimetric method!
This standard is applicable to the determination of chromium content in nickel-based alloy powder. Determination range: 2.00%~~30.00%. UDC E69. 245-492. 2
GB 8638.488
This standard complies with GB1467-78 "General Principles and General Provisions of Chemical Analysis Methods for Metallurgical Products". 1 Method Summary
The sample is dissolved in acid, and chromium is oxidized to hexavalent chromium with ammonium persulfate in sulfuric acid-phosphoric acid medium with silver nitrate as catalyst, and the chromium content is titrated with ammonium ferrous sulfate solution.
2 Reagents
Hydrochloric acid (μ1.19 g/mL).
Nitric acid (p1.42g/mL).
Hydrofluoric acid (μ1.15g/mL).
Sulfuric acid (p1.84g/mL).
Phosphoric acid (p 1. 67 g/mL).
Ammonium persulfate solution (25%): Prepare immediately before use. 2.7
Manganese sulfate solution (0.5%).
Sodium chloride solution (5%).
2.9Sodium diphenylamine sulfonate solution (0.2%). 2.10N-phenylanthranilic acid solution (0.2%): Weigh 0.2gN-phenylanthranilic acid and dissolve it in 100mL sodium carbonate aqueous solution (containing 0.2g sodium carbonate), and heat to dissolve. 2.11 Silver nitrate solution (1%): Weigh 1g of silver nitrate and dissolve it in water, add a few drops of nitric acid and dilute it with water to 100mL, mix it, and store it in a brown bottle.
2.12 Potassium dichromate standard solution: Weigh 5.6582g of standard potassium dichromate (pre-dried at 105℃ for 1h, placed in a desiccator, and cooled to room temperature) and place it in a 300mL beaker, dissolve it with water, transfer it to a 2000mL volumetric flask, dilute it with water to the mark, and mix it. This solution contains 1.00mg chromium in 1mL
2.13 Ammonium ferrous sulfate standard solution:
2.13.1 Preparation: Weigh 10g of ammonium ferrous sulfate, dissolve it with sulfuric acid (5+95), transfer it to a 1000mL volumetric flask, dilute it with sulfuric acid (5+95) to the mark, and mix it. (This solution needs to be calibrated with a potassium dichromate standard solution with a similar chromium content to the sample.) 2.13.2 Calibration: Transfer two portions of potassium dichromate standard solution (2.12) with a similar chromium content to the sample into 500mL beakers, add 4mL phosphoric acid (2.5) and 30mL sulfuric acid (1+1), and dilute to 200mL with water. Titrate with ammonium ferrous sulfate standard solution (2.13) until the solution turns pale yellow, add 3 drops of N-phenylated anthranilic acid solution (2.10), and continue titrating until the solution changes from rose red to bright green. The difference in the volume of ammonium ferrous sulfate standard solution consumed by the three portions of chromium standard solution should not exceed 0.05mL, and the average value should be taken. Approved by China National Nonferrous Metals Industry Corporation on January 11, 1988 and implemented on January 1, 1989
GB 8638.4-88
Calculate the titer of ammonium ferrous sulfate standard solution on chromium according to formula (1): V:CX 10
The titer of ammonium ferrous sulfate standard solution on chromium, g/mL; CThe concentration of potassium disulfide standard solution, m/mL;.The volume of ammonium ferrous sulfate solution consumed in titration, mL. 3 Analysis steps
3.1 Number of determinations
Measure twice in parallel and take the average value.
3.2 Sample size
Weigh 0.2000~0.5000g of sample.
3.3 Test
3.3.1 Place the sample (3.2) in a 500mL beaker, add 15mL hydrochloric acid (2.1) and 2mL nitric acid (2.2), and dissolve by heating at low temperature (for poorly soluble samples, hydrofluoric acid (2.3) can be added dropwise to assist dissolution). Add 4mL phosphoric acid (2.5) (for samples with high tungsten content, add 6mL) and 8mL sulfuric acid (2.1), evaporate until sulfuric acid fumes appear, add nitric acid (2.2) dropwise to oxidize until the carbides are completely destroyed, and continue evaporating until sulfuric acid fumes appear, and cool. 3.3.2 Add water to about 100 mL, heat at low temperature to dissolve the salts, dilute with water to about 200 mL, add 5 mL of silver nitrate solution (2.11), 20 mL of ammonium persulfate solution (2.6), and boil until the chromium is completely oxidized (the red color of permanganate appears, indicating that the chromium has been completely oxidized. If the manganese content in the sample is too low, add 1 drop of manganese sulfate solution (2.7) to oxidize it. Add glass beads to prevent the solution from overheating and splashing. Continue boiling for 5 minutes, add 5 mL of sodium chloride solution (2.8). Boil until the red color disappears [if the red color does not disappear, add more sodium chloride solution (2.8)], and continue boiling for 8 to 10 minutes. min, so that the silver chloride precipitate condenses and sinks, and cools to room temperature with running water. 3.3.3 Titrate with standard ammonium ferrous sulfate solution (2.13) until the solution turns light yellow, add 3 drops of N-phenylated anthranilic acid solution (2.10) containing tungsten sample, and then add 2 drops of sodium diphenylamine sulfonate (2.9), and continue titrating until the solution changes from rose red to bright green. Calculation of analysis results
Calculate the percentage of chromium according to formula (2):
Where T
Cr(%) =
T:V×100
Titer of ammonium ferrous sulfate standard solution on chromium, g/ml; v. Volume of ammonium ferrous sulfate standard solution consumed in titration, mL; ma
Sample weight, g;
Note: When containing vanadium, the calculated result must be corrected, 1% vanadium is equivalent to 0.31% chromium. 5 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 1. Qiu 1
Chromium content
2. 00 ~5. 00
5. 00~10. 00
≥10.00～15,00
≥15.00～20. 00
220.00~30.00
Allowance
Additional Notes:
GB8638.4-88
This standard was drafted by the Iron and Steel Research Institute of the Ministry of Metallurgical Industry. This standard was drafted by the Iron and Steel Research Institute of the Ministry of Metallurgical Industry. The main drafters of this standard are Yang Qiuping and Zheng Guanghe. 377
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