This standard is applicable to the determination of iron content in nickel-based alloy powder. Determination range: 1.00% to 20.00%. This standard complies with GB 1467-78 "General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products". GB/T 8638.6-1988 Chemical analysis method for nickel-based alloy powder Titanium trichloride-potassium dichromate titration method for determination of iron content GB/T8638.6-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis method for nickel-based alloy powder
Determination of iron content-. Titaniun trichloride-potassium dichromate titrimetric method This standard is applicable to the determination of iron content in nickel-based alloy powder. Determination range: 1.00% to 20.00%. UDC 669. 245-492. 2
GB 8638.6--88
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 by emitting perchloric acid fumes. The iron precipitate is separated from chromium, nickel and other elements by ammonia water. The precipitate is dissolved in hydrochloric acid, sodium tungstate is used as an indicator, titanium trichloride is used to reduce iron to divalent, sodium diphenylamine sulfonate is used as an indicator, and potassium dichromate standard solution is used for titration.
2 Reagents
2.1 Ammonium chloride.
2.2 Hydrochloric acid (p1.19 g/mL).
2.3 Nitric acid (1.42 g/mL).
2.4 Hydrofluoric acid (p1.15 g/mL).
Perchloric acid (p1.67 g/mL).
Ammonium hydroxide (p0.90 g/mL).
2.7 Phosphoric acid (p1.69 g/mL).
2.8 Sulfuric acid (p1.84 g/mL).
2.9 Hydrogen peroxide (commercially available 30%). wwW.bzxz.Net
Hydrochloric acid (1+1).
Hydrochloric acid (1+9).
Ammonium hydroxide (1+1).
Ammonium hydroxide (5+95).
Sodium diphenylamine sulfonate solution (0.2%).
Potassium dichromate solution (0.1%).
Sodium tungstate solution (25%): Weigh 25g sodium tungstate and dissolve it in water, add 5mL phosphoric acid (2.7), and dilute it to 100mL with water. Titanium trichloride solution: Take 25mL titanium trichloride solution (15%~20%), dilute it to 100mL with hydrochloric acid (2.10), and mix well. 2.17
2.18Titanium trichloride solution: Take 10mL titanium trichloride solution (15%~20%), dilute it to 200mL with hydrochloric acid (2.11), and mix well. 2.19 Sulfuric acid-phosphoric acid mixture: Pour 150 mL of ethanol (2.8) into 700 mL of water while stirring, then add 150 mL of phosphoric acid (2.7) and mix well.
2.20 Ammonium ferrous sulfate solution (2%): Weigh 2 g of ammonium ferrous sulfate, add water and 5 mL of sulfuric acid (2.8), dissolve, (if the solution is turbid, filter with filter paper), dilute with water to 100 mL, and mix. Approved by China National Nonferrous Metals Industry Corporation on January 11, 1988 380
Implemented on January 1, 1989
GB 8638.6-88
2.21 Potassium dichromate standard solution [c (1/6K, Cr.0,) = 0.01 mol/L]: Weigh 0.4903 g of standard potassium dichromate that has been dried at 105C for 1 hour and dissolve it in water, transfer it into a 1000 mL volumetric flask, dilute it to the mark with water, and mix it well. 3 Analysis steps
3.1 Number of determinations
Measure twice in parallel and take the average value.
3.2 Sample size
Weigh 0.1000~0.5000 g of sample. (Control the iron content to 5~25 mg). 3.3 Blank test
Carry out a blank test with the sample.
3.4 ​​Determination
3.4.1 Place the sample (3.2) in a 250mL beaker, add 30mL hydrochloric acid (2.2), cover with Table III, dissolve at low temperature, add nitric acid (2.3) dropwise after the action stops, and continue heating until the sample is completely dissolved [add hydrofluoric acid (2.4) dropwise to dissolve the insoluble sample]. 3.4.2 Add 10mL perchloric acid (2.5), evaporate until white smoke appears and reflux for 4~5min, cool slightly, add 150mL hot water and 2~3g ammonium chloride (2.1), stir, wait for the salt to dissolve, add ammonium hydroxide (2.12) dropwise until iron hydroxide precipitates, add 10mL in excess, remove and let stand for a while, filter with fast filter paper, and wash the beaker and precipitate 7~8 times with hot ammonium hydroxide solution (2.13). 3.4.3 Dissolve the precipitate in 20 mL of hot hydrochloric acid (2.10) and place it in the original beaker. Wash the filter paper with hot water to adjust the solution volume to about 150-200 mL. Add 15 drops of sodium tungstate solution (2.16), mix well, add titanium trichloride solution (2.17) until the solution turns light yellow, and continue to add titanium difluoride solution (2.18) until the solution turns a stable blue. Slowly add potassium dichromate solution (2.15) until the blue color disappears completely. 3.4.4 Immediately add 20 mL of sulfuric acid-phosphoric acid mixed acid (2.19) and 3 drops of sodium diphenylamine sulfonate solution (2.14). Titrate with potassium dichromate standard solution (2.21) until the solution turns a stable purple color. Record the volume of potassium dichromate standard solution (2.21) consumed. 3.5 Calibration of reagent blank and indicator
3.5.1 Add 6.00mL of ammonium ferrous sulfate solution (2.20) to the blank test solution that has been tested with the sample up to 3.4.3, and continue with 3.4.4.
3.5.2 Add 6.00mL of ammonium ferrous sulfate solution (2.20), and then titrate with potassium dichromate standard solution (2.21) until the solution turns a stable purple color, and record the volume of potassium dichromate standard solution (2.21) consumed. 3.5.3 The volume of potassium dichromate standard solution consumed for the first time minus the volume of potassium dichromate standard solution consumed for the second time is the volume of potassium dichromate standard solution consumed for the reagent blank and indicator. Calculation of analytical results
According to formula (1), calculate the percentage of iron:
Fe(%) = (e- V)×c× 0. 55 85 × 100m
Wherein: V-volume of potassium dichromate standard solution consumed when titrating the test solution, mL; V, —-volume of potassium dichromate standard solution consumed by reagent blank and indicator, mL; m-—sample weight, g,
concentration of one-sixth of the amount of potassium dichromate molecules in the potassium dichromate standard solution, mol/L; 0.05585 —-the mass of iron in 1.00mL of potassium dichromate standard solution equivalent to c (1/6K.Cr.0.) = [.000mol1/L, g, 5 Allowable difference
The difference in analytical results between laboratories should not be greater than the allowable difference listed in Table 1. +()
Additional Notes:
Iron Content
1. 00 ~3. 00
>3.00~6.00
>6.00～10.00
>10.0015.00
>15.0020.00
GB 8638.6
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 drafter of this standard is Wang Zhichun.
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