This standard is applicable to the determination of cobalt content in nickel-based alloy powder. Determination range: 0.10% to 3.00%. This standard complies with GB 1467-78 "General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products". GB/T 8638.7-1988 Chemical analysis method for nickel-based alloy powder - Determination of cobalt content by nitrosyl R salt spectrophotometry GB/T8638.7-1988 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 cobalt content- Nitroso-R salt spectrophotometric method
Nickel base allay pawder-- Determination of cobalt content- Nitroso-R salt spectrophotometric method This standard is applicable to the determination of cobalt content in nickel-based alloy powder. Determination range: 0.10%~3.00%. UDC669.245-492.2
：543.962
GB 8638.7
This standard complies with GB1467-78 "General Principles and General Provisions of Standards for Chemical Analysis Methods of Metallurgical Products" 1 Method Summary
The sample is decomposed with acid. In the presence of ammonium citrate and sodium nitrite, when the pH of the solution is 5.5-7.5, divalent diamond is rapidly oxidized to valence and forms a red complex with nitroso R salt. Its absorbance is measured at a wavelength of 530nm on a spectrophotometer. 2 Reagents
2.1 Hydrochloric acid (p1.19 g/mL).
2.2 Nitric acid (1.42 g/mL).
2.3 Hydrofluoric acid (p1.15 g/mL).
2.4 Sulfuric acid (1+1).
2.5 Sulfuric acid-phosphoric acid mixture: 150mL sulfuric acid (1.81g/mL) mixed with 150ml phosphoric acid (p1.69g/mL) and 700mL water.
2.6 Ammoniacal ammonium citrate solution (25%): weigh 62.5g ammonium citrate and place it in a 400mL beaker, add 200mL water to dissolve, add 5ml. ammonium hydroxide (0.90g/ml.), dilute with water to 250mL, and mix well. 2.7 Sodium nitrite solution (0.5%).
2.81-Nitroso-2-naphthol-3.6-disulfonic acid sodium (nitroso R salt) solution (0.5%), prepare it when used. 2.9 Cobalt standard stock solution: weigh 0.1000g of pure cobalt and place it in a 250mL beaker, add 15mL of sulfuric acid (2.4), cover the surface with blood, heat to dissolve, cool to room temperature, transfer to a 1000mL volumetric flask, dilute to scale with water, and mix. This solution contains 100μ cobalt in 1mL. 2.10 Cobalt standard solution: transfer 50.00mL of cobalt standard stock solution (2.9), place it in a 250mL volumetric flask, dilute to scale with water, and mix. This solution contains 20μ cobalt in 1ml.
2.11 Cobalt standard solution: transfer 25.00mL of cobalt standard stock solution (2.9), place it in a 250mL volumetric flask, dilute to scale with water, and mix. This solution contains 10ug cobalt in 1mL.
3·Instrument
Spectrophotometer. bZxz.net
4 Analysis steps
4.1 Determination times
Measure twice in parallel and take the average value.
Approved by China National Nonferrous Metals Industry Corporation on January 11, 1988 and implemented on January 1, 1989
4.2 Sample quantity
Weigh 0.2000g of sample.
4.3 Determination
GB 8638.7-88
Put the sample (4.2) in a 100mL beaker, add 10mL hydrochloric acid (2.1) and 2mL nitric acid (2.2), heat at low temperature to dissolve 4.3.1
[You can add a few drops of hydrofluoric acid (2.3) to help dissolve]. Add 10mL sulfuric acid-phosphoric acid mixture (2.5), continue heating and evaporating until sulfuric acid smoke appears for 1~2 minutes, remove and cool slightly. Add 20mL of water, dissolve the salts with slight heat, remove and cool to room temperature, transfer to a 100mL volumetric flask, dilute to scale with water, and mix well.
4.3.2 Transfer two 5mL portions of the test solution and place them in 50mL volumetric flasks respectively, and proceed as per 4.3.3 and 4.3.4. 4.3.3 Color development solution: add 10mL of ammonia ammonium citrate solution (2.6), 1mL of sodium nitrite solution (2.7), and 5mL of nitroso R salt solution (2.8), mix, let stand for 1min, add 10mL of sulfuric acid (2.4), heat in boiling water for 30s, remove, cool to room temperature with running water, dilute to scale with water, and mix well.
4.3.4 Reference solution: add 10mL ammoniacal ammonium citrate solution (2.6), 10mL sulfuric acid (2.4), mix well, add 5mL nitroso R salt solution (2.8) and cool to room temperature with running water, dilute to scale with water, and mix. 4.3.5 Transfer the colorimetric solution and reference solution into a 1-3cm cuvette, and measure its absorbance at a wavelength of 530nm using the reference solution (4.3.4) as a reference. Find the corresponding amount of cobalt from the working curve. 4.4 Drawing of the working curve
4.4.1 Weigh a portion of pure iron without cobalt (its amount corresponds to the sample weight) to replace the sample, and proceed as per 4.3.1. 4.4.2 Take six portions of 5 mL of solution (4.4.1) and place them in a group of 50 mL volumetric flasks. Take 0, 1.00, 3.00, 5.00, 7.00, and 10.00 mL of cobalt standard solution (2.11). When the cobalt content of the sample is greater than 1.00%, take 0, 1.00, 2.00, 4.00, 6.00, and 8.00 mL of cobalt standard solution (2.10) and place them in the above group of volumetric flasks. The following is carried out according to Section 4.3.3. 4.4.3 Pour the colorimetric solution into a 13 cm colorimetric III, use the zero concentration solution in the standard series as a reference, measure its absorbance at a wavelength of 530 nm on a spectrophotometer, and draw a working curve with the cobalt content as the horizontal axis and the absorbance as the vertical axis. 5 Calculation of analysis results
Calculate the percentage of cobalt according to formula (1):
Co(%) = m XV.X 10-6
m. xV
Wherein: mi -
-the amount of cobalt found from the working curve, ug; -the volume of the sample solution, mL;
V. —the total volume of the sample solution, mL;
-the weight of the sample,.
6 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 1. Table 1
0. 10 ~ 0. 50
>0.50~1. 00
>1. 00~3. 00
Allowance
Additional Notes:
GB8638.7--88
This standard was drafted by the Central Iron and Steel Research Institute of the Ministry of Metallurgical Industry. This standard was drafted by the Central Iron and Steel Research Institute of the Ministry of Metallurgical Industry. The main drafter of this standard is Yang Qiuping.
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