GB/T 8638.9-1988 Chemical analysis methods for nickel-based alloy powders - Sodium thiosulfate iodine method for determination of copper content GB/T8638.9-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis method of nickel base alloy powder
Determination of copper content by sodium thiosulfate-iodimetric method
Nickel base alloy powder .- Determination of copper content Thiosulfate-iodimetric method This standard is applicable to the determination of copper content in nickel base alloy powder. Determination range: 1.00%~-5.00%. UDC 669. 245-492. 2
GB 8638.9-88
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. Copper reacts with sodium thiosulfate in sulfuric acid medium to form cuprous sulfide precipitation, which is separated from interfering elements such as iron, chromium, and manganese. The precipitation is burned into copper oxide, melted with potassium pyrosulfate, and potassium iodide is added to acetic acid medium. The free iodine is titrated with sodium thiosulfate standard solution using starch as an indicator.
2 Reagents
2.1 Potassium pyrosulfate.
2.2 Potassium iodide.
2.3 Ammonium fluoride.
2. 4 Hydrochloric acid (p1.19 g/mL).
2.5 Nitric acid (p1.42 g/mL).
2.6 Sulfuric acid (p1.84 8/mL).
Phosphoric acid (p1. 69 g/mL).
Glacial acetic acid (p1.05 g/mL).
Sulfuric acid (1+1).
Sodium thiosulfate solution (50%).
Ammonium hydroxide (1+1).
Ammonium thiocyanate solution (20%).
2.13 Starch solution (1%): Weigh 1 soluble starch and mix it with distilled water to make a paste, pour it into 80mL boiling water, boil until the starch is completely dissolved. After cooling, dilute to 100mL and mix well. Prepare it when needed. 2.14 Copper standard solution: Weigh 1.0000g pure copper, such as 20mL water and 10mL nitric acid (2.5), heat to dissolve, add 10mL sulfuric acid (2.6), evaporate sulfuric acid fumes for 1min, and cool. Dissolve the salts with water, transfer to a 1000mL volumetric flask, dilute to the mark with water, and mix well. This solution contains 1 mg copper in 1mL.
2.15 Sodium thiosulfate standard solution [c(Na.S,0·5H0)=0.01mol/L]. 2.15.1 Preparation: Weigh 2.48g sodium thiosulfate (Na.S,O·5H.0) and dissolve it in boiled and cooled distilled water, add 0.2g anhydrous sodium carbonate, dilute to 1000mL with boiled and cooled distilled water after complete dissolution, and mix well. Store in a brown bottle and leave for 8 to 11 days for calibration.
2.15.2 Calibration: Take three portions of 20.00mL copper standard solution (2.14) and place them in 300mL conical flasks respectively. Add 30mL water and drop ammonium hydroxide (2.11) until the solution turns blue. Then drop glacial acetic acid (2.8) to make the blue disappear and add 2mL, 3g iodide bomb (2.2) to mix well. Place in dark place for 2min. Drop sodium thiosulfate standard solution (2.15.1) until the solution turns pale yellow. Add 5mL starch solution (2 .13), 10mL ammonium thiosulfate solution (2.12), continue to titrate with sodium thiosulfate standard solution (2.15.1) until the solution reaches position E1: Calculate the titer of sodium thiosulfate standard solution on copper according to formula (1): T
W Zhong: T
The titer of sodium thiosulfate standard solution on copper, g/ml; The concentration of copper standard solution, g/ml;
W--The volume of sodium thiosulfate standard solution consumed in titration, r.LV. The volume of copper standard solution transferred, ml
3 Analysis steps
3.1 Number of measurements
Measure twice in parallel and take the average value.
3.2 Sample quantity
Weigh the sample according to Table 1:
Copper content, %
1.00~3.00
3. 00~~5.00wwW.bzxz.Net
3.3 Blank test
Carry out a blank test together with the sample.
3.4 ​​Determination
Weigh the sample,
3.4.1 Place the sample (3.2) in a 500mL beaker, add 15mL hydrochloric acid (2.4) and 2ml nitric acid (2.5) and heat at low temperature to dissolve [for insoluble samples, add 0.5g ammonium fluoride (2.3) to assist dissolution], and after the sample is completely dissolved, add 20mL phosphoric acid (2.7) and 20mL sulfuric acid (2.9), and continue heating and evaporating until sulfuric acid smoke appears. Cool, add 250~300mL water to dissolve the salts, add 60~80mL sodium thiosulfate solution (2.10) under constant stirring, boil for about 10 min to make the precipitate condense and the solution clear. 3.4.2 Filter with medium-speed filter paper, transfer all the precipitate onto the filter paper with hot water, wash the precipitate and filter paper with water 5~7 times, put the filter paper and the precipitate in a porcelain crucible, ash, burn at 500~550℃ for 10min, cool, add 45B potassium pyrosulfate (2.1), heat to melt, cool. Put it in a 300mL beaker, add 20mL hot water, add a few drops of sulfuric acid (2.6), heat to overflow the molten block, wait for the molten block to dissolve, wash the quasi-Handan crucible with water, and cool.
3.4.3 Add 0.5g of ammonium fluoride (2.3), and drop ammonium hydroxide (2.11) until the solution turns blue. Add 3mL of glacial acetic acid (2.8) and 3g of potassium iodide (2.2) and place in a dark place for 2min. Immediately titrate with sodium thiosulfate standard solution (2.15) until the solution turns pale yellow. Add 5ml of starch solution (2.13) and 10mL of ammonium thiocyanate solution (2.12), and continue titrating with sodium thiosulfate standard solution (2.15) until the solution turns from blue to milky white.
Calculation of analysis results
Calculate the percentage of copper according to formula (2):
Wherein: 7
T.(V-- V2) × 100
Cu(%) -
Titre of sodium thiosulfate standard solution for copper, nom/mL; ... - The volume of thiosulfate standard solution consumed in titrating blank solution, mL; 390
GB8638.9-88
V. - The volume of sodium thiosulfate standard solution consumed in titrating test solution, mL; m. ... Sample weight,.
5 Allowable Difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 2 Table 2
Copper Basis
1.00~3.00
>3.00~5.00
Additional Notes:
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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