This standard specifies the determination of aluminum content in nickel-chromium-iron alloys by chrome azuro blue S photometric method. This standard is applicable to the determination of aluminum content in nickel-chromium-iron alloys. Determination range: 0.050% to 0.500%. JB/T 6326.7-1992 Chemical analysis method for nickel-chromium alloys Chrome azuro blue S photometric method for determination of aluminum content JB/T6326.7-1992 Standard download decompression password: www.bzxz.net

1 Subject content and scope of application
Mechanical Industry Standard of the People's Republic of China
Chemical analysis method of nickel-chromium alloy
Determination of aluminum content by chrome azure S photometry
This standard specifies the determination of aluminum content in nickel-chromium alloy by chrome azure S photometry. This standard is applicable to the determination of aluminum content in nickel-chromium alloy. 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
JB/T 6326.7—92
The sample is dissolved with mixed acid and high oxygen acid pipe smoke to oxidize chromium to hexavalent. The presence of high valent chromium does not affect the determination of aluminum. Use CyDTA-Zn and mannitol to mask copper, iron and titanium. Under the condition of pH 5.7, use chrome azuro blue S to develop the color and measure its absorbance. The matrix element nickel has an inhibitory effect on the color development of aluminum and has a certain background absorption. Use the opposite amount of nickel as the base to make a working curve to offset the shadow.
4 Reagents
Sodium hydroxide.
4.2 Zinc oxide.
Hydrochloric acid (density pl.19g/ml).
Nitric acid (density pl.42g/ml).
Perchloric acid (density pl.67g/ml).
Ammonium hydroxide (density po.90g/ml).
Nitric acid (1+1).
Hydrochloric acid-nitric acid mixed acid: hydrochloric acid (4.3) + nitric acid (4.4) (1+1). Hydrochloric acid (1+1).
Hydrochloric acid (1 mol/L).
Ammonium hydroxide (1+4).
Cyclohexanediaminetetraacetic acid-zinc solution (hereinafter referred to as CyDTA-Zn) (0.1 mol/L): Weigh 8.5 g zinc oxide (4.2), dissolve in 4.12
35 ml hydrochloric acid (4.9), weigh 34.6 g CyDTA and place it in a 400 ml beaker, add 200 ml water, heat, and drop ammonium hydroxide (4.11) until it is just dissolved. Combine the two solutions and mix well, adjust the acidity to about pH 5.5, transfer to a volumetric flask, dilute to 1000 ml, and mix well. 4.13 Mannitol solution (50 g/L).
4.14 Hexamethylenetetramine buffer solution (pH 5.7): weigh 30g hexamethylenetetramine, dissolve in water, add 4ml hydrochloric acid (4.3), dilute to 100ml.
4.15 Ammonium fluoride solution (5g/L): store in a plastic bottle. Approved by the Ministry of Machinery and Electronics Industry on 1992-06-26, implemented on 1993-01-01
Chrome Azure S solution (1g/L).
JB/T6326.7-92
4.17 Nickel solution: weigh 0.100g pure nickel (containing less than 0.001% aluminum), dissolve with 5ml nitric acid (4.7), remove yellow smoke, transfer to a 100ml volumetric flask, dilute with water to the scale and mix well. This solution contains 1mg nickel in 1ml. 4.18 Aluminum standard solution; weigh 0.1000g pure aluminum (purity above 99.9%), place in a polytetrafluoroethylene beaker, add 1g sodium hydroxide (4.1), 5ml water, and heat until completely dissolved. Add hydrochloric acid (4.3) to acidify and add 8ml excess, transfer to a 1000ml volumetric flask, add water to the scale, and mix well. This solution contains 0.10mg aluminum per ml. 4.18.1 Transfer 2.00ml aluminum standard solution (4.18) to a 100ml volumetric flask, add 10 drops of hydrochloric acid (4.9), dilute to the scale with water, and mix well. This solution contains 2μg aluminum per ml.
4.18.2 Transfer 5.00ml aluminum standard solution (4.18) to a 100ml volumetric flask, add 10 drops of hydrochloric acid (4.9), dilute to the scale with water, and mix well. This solution contains 5μg aluminum per ml.
4.19. Methyl solution: (1g/L)
5 Analysis steps
5.1 Sample volume
Weigh 0.1000g of sample.
5.2 Blank test
Perform a blank test together with the sample. bzxz.net
5.3 Determination
5.3.1 Place the sample in a 125ml conical beaker, add 10ml of hydrochloric acid-nitric acid mixture (4.8), heat at low temperature, wait until the sample is dissolved, add 3ml of peroxy acid (4.5) and smoke until chromium is oxidized to hexavalent, then keep for 12 minutes, cool, add water to dissolve the salts, transfer the solution and the precipitated silicic acid into a 100ml volume, dilute to the scale, and mix well. 5.3.2 Take 2 portions of 5 ml of the clear solution on 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 development solution.
5.3.3 Add a drop of methyl solution (4.19) and adjust the solution to yellow with ammonium hydroxide (4.11), and immediately adjust the solution to red with hydrochloric acid (4.10). Use a pipette to add reagents except ammonium fluoride in the order of Table 1: (mix thoroughly after each reagent is added): dilute to the scale with water and mix. Let stand for 20 minutes (color development should be performed one by one at room temperature above 30°C) and measure its absorbance. 5.3.4 Select a 2 cm or 3 cm colorimetric blood according to the aluminum content and measure its absorbance at a wavelength of 560 nm on a spectrophotometer for the reference solution. After subtracting the absorbance of the reagent blank, the aluminum content of the sample can be obtained on the corresponding working curve. Table 1
Test engraving addition amount
Reagent name
Ammonium fluoride (4.15)
Hydrochloric acid (4.10)
CyDTA-Zn (4.12)
Mannitol (4.13)
Chrome azuro blue S (4.16)
Buffer solution (4.14)
5.4 Drawing of working curve
Reference solution
5 0ml color development
100ml color development
50ml color development
100ml color development
Take 6 portions of nickel solution (4.17) with the same amount of nickel 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 (4.18.1 or 4.18.2) of corresponding concentration according to Table 2. The following is carried out according to 5.3.3~16
JB/T6326.7—92
5.3.4. Take the color development solution without aluminum standard solution as the reference solution and measure its absorbance. Draw a working curve. Table 2
Aluminum standard solution
μg/ml
Color development volume
Cuvette
Calculation of analysis results
Calculate the percentage of aluminum according to the following formula
0.50~0.20
Wherein: m—amount of aluminum found from the working curve, g; V-—total volume of test solution, ml,
V,—volume of test solution taken, ml;
m—sample amount, g.
Allowance
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 3. Table 3
Aluminum content
0.050~0.100
>0.100~0.500
Additional notes:
This standard is proposed and managed by the Shanghai Electrical Science Research Institute of the Ministry of Machinery and Electronics Industry. This standard is drafted by the Shanghai Materials Research Institute of the Ministry of Machinery and Electronics Industry. The main drafter of this standard is Fan Jufen.
Aluminum content
0.20~0.50
Allowable difference
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