This standard specifies the method for determining the aluminum content in nickel-chromium and nickel-chromium-iron alloys using the chrome azuro blue S photometric method. This standard is applicable to the determination of aluminum content in nickel-chromium and nickel-chromium-iron alloys. Determination range: 0.050% to 0.500%. JB/T 6326.8-1992 Chemical analysis method for nickel-chromium and nickel-chromium-iron alloys Chrome azuro blue S photometric method for determination of aluminum content JB/T6326.8-1992 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Chemical analysis method of nickel-chromium and nickel-chromium-iron alloys Chrome azure S photometric method for aluminum content
1 Subject content and scope of application
JB/T6326.8-92
This standard specifies the method for determining the aluminum content of nickel-chromium and nickel-chromium-iron alloys using the chrome azure S photometric method. This standard is applicable to the determination of aluminum content in nickel-chromium and nickel-chromium-iron alloys. Determination range: 0.050%~0.500%: 2 Reference standards
GB1467 General principles and general provisions for chemical analysis methods of metallurgical products. 3 Method summary
The sample is dissolved with mixed acid. The perchloric acid is fumed to oxidize the chromium to hexavalent and volatilize and remove it in the form of chromyl chloride. The remaining chromium does not affect the determination of aluminum.
Iron is reduced with ascorbic acid, and the divalent iron does not affect the determination of aluminum. Under the condition of pH 5.7, chrome azure S is used for color development and its absorbance is measured. The matrix elements have an inhibitory effect on the color development of aluminum and have a certain background absorption. Use the same amount of nickel as the base to make a working curve to offset the influence.
4 Reagents
4.1 Sodium hydroxide
4.2 Hydrochloric acid (density p1.19g/ml).
Nitric acid (density pl.42g/ml).
Perfluoric acid (density p1.67g/ml).
Ammonium hydroxide (density p0.90g/ml).
Hydrochloric acid-nitric acid mixed acid: hydrochloric acid (4.2) + nitric acid (4.3) (1+1). 4.7
Hydrochloric acid (1+1).
Hydrochloric acid (1mol/L).
Nitric acid (1+1).
Ammonium hydroxide (1+4).
Ascorbic acid solution (10g/L).
2 Hexamethylenetetramine buffer solution (300g/L). Store in a plastic bottle. 4.12
Ammonium fluoride solution (5g/L). Store in a plastic bottle, 4:14
Chrome azure S (0.5g/L).
4.15 Nickel solution: Weigh 0.100g pure nickel (containing less than 0.001% aluminum), heat and dissolve with 5ml nitric acid (4.9), drive off nitrogen oxides, transfer to a 100ml volumetric flask, and dilute to scale. Mix well. This solution contains 1mg nickel in 1ml, 4.16 Aluminum standard solution: Weigh 0.1000g pure aluminum (more than 99.9%) and place it in a polytetrafluoroethylene beaker, add 1g sodium hydroxide (4.1), 5ml water, and heat until the pure aluminum is completely dissolved. Add hydrochloric acid (4.2) to acidify and add 8ml excess, transfer to a 1000ml volumetric flask, dilute with water to the scale, and mix. This solution contains 0.10mg aluminum in 1ml. JB/T6326.8-92
4.16.1 Transfer 2.00ml aluminum standard solution (4.16) to a 100ml volumetric flask, add 10 drops of hydrochloric acid (4.7), dilute with water to the scale, and mix. This solution contains 2μg aluminum in 1ml.
4.16.2 Transfer 5.00ml aluminum standard solution (4.16) to a 100ml volumetric flask, add 10 drops of hydrochloric acid (4.7), dilute with water to the scale, and mix. This solution contains 5ug aluminum in 1ml.
4.17 Methyl orange solution (1g/L).
5 Analysis steps
5.1 Sample volume
Weigh 0.1000g of sample.
5.2 Blank test
Carry out a blank test together with the sample. Www.bzxZ.net
5.3 Determination
5.3.1 Place the sample in a 125ml conical beaker, add 5ml of hydrochloric acid-nitric acid mixture (4.6), heat at low temperature, and after the sample is dissolved, add 5ml of perchloric acid (4.4) to oxidize chromium to hexavalent, and add a few drops of hydrochloric acid (4.2) to evaporate the chromium. Repeat several times until no yellow-brown gas emerges, cool, and add water to dissolve the salts. Transfer the solution and the precipitated silicate into a 100ml volumetric flask with a glass rod with a rubber head and dilute to the scale and mix well.
5.3.2 Take two portions of 5 ml of the upper layer of the sample and the blank test solution (5.2), add ammonium fluoride solution (4.15) to one portion as the reference solution, and the other portion as the color developing solution. 5.3.3 Add 1 drop of methyl orange solution (4.17) and adjust the solution with ammonium hydroxide (4.10) until the solution is just yellow, and immediately adjust it with hydrochloric acid (4.8) until it is red. Use a pipette to add the reagents except ammonium fluoride in the order of Table 1. (After adding each portion of reagent, it must be fully mixed). Dilute to the scale with water and mix well. When the temperature is about 30℃, the reading should be completed within 2 to 3 minutes. When it is about 20℃, let it stand for 5 to 10 minutes; when it is about 10℃, let it stand for 20 minutes.
5.3.4 According to the aluminum content, select a 1cm or 2cm colorimetric plaque to measure the absorbance of the reference solution at a wavelength of 550nm on the spectrophotometer. After subtracting the absorbance of the reagent blank, the aluminum content of the sample can be found on the corresponding working curve. Table 1
Amount of reagent added
Test name
Ammonium chloride (4.13)
Hydrochloric acid (4.8)
Ascorbic acid (4.11)
Chrome azuro (4.14)
Buffer solution (4.12)
5.4 Drawing of working curve
Reference solution
50ml color development
100ml color development
Color development solution||tt| |50ml color development
100ml color development
Add ascorbic acid to rinse the sticky
test solution at the bottleneck
Take 6 portions of nickel solution (4.15) with the same nickel content as the sample, and place them in 6 volumetric flasks respectively. According to the aluminum content of the sample, add 0.00, 1.00, 2.00, 3.00, 4.00, 5.00ml of aluminum standard solution (4.16.1 or 4.16.2) of corresponding concentration according to Table 2. The following is carried out according to 5.3.3~5.3.4. Take the color development solution without aluminum standard solution as the reference solution and measure its absorbance. Draw the working curve, 19
Aluminum standard solution
Colorimetric volume
Colorimetric blue
Analysis result calculation
Calculate the percentage of aluminum according to the following formula
JB/T6326.892
0.050~0.20
AL (%)-
Where: m——amount of aluminum found from the working curve, g;—total volume of test solution, ml,
V,—volume of test solution taken, ml;
sample weight, g.
.Allowed total
The difference in analysis results between laboratories should not be greater than the allowable difference table listed in Table 3
0.050~0.100
>0.10~0.500
Additional instructions:
This standard was proposed and managed by the Shanghai Electrical Science Research Institute of the Ministry of Machinery and Electronics Industry. This standard was drafted by the Shanghai Materials Research Institute of the Ministry of Machinery and Electronics Industry. The main drafter of this standard is Fan Jufen.
0.20~0.50
Allowed difference
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