This standard specifies the method for the determination of phosphorus content in nickel-chromium and nickel-chromium-iron alloys by phosphorus-vanadium-molybdenum yellow extraction photometry. This standard is applicable to the determination of phosphorus content in nickel-chromium and nickel-chromium-iron alloys. Determination range: 0.005% to 0.030%. JB/T 6326.12-1992 Chemical analysis method for nickel-chromium and nickel-chromium-iron alloys Phosphorus-vanadium-molybdenum yellow extraction photometry determination of phosphorus content JB/T6326.12-1992 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Chemical analysis method for nickel-chromium and nickel-chromium-iron alloys Phosphorus vanadium molybdenum yellow extraction photometric method for determination of phosphorus content
Subject content and scope of application
This standard specifies the method for determining phosphorus content in nickel-chromium and nickel-chromium-iron alloys by phosphorus vanadium molybdenum yellow extraction photometric method. JB/T6326.12-92
This standard is applicable to the determination of phosphorus content in nickel-chromium and nickel-chromium-iron alloys. Determination range: 0.005%-0.030%. 2 Reference standards
GB1467 General principles and general provisions for chemical analysis methods for metallurgical products. 3 Method summary
The sample is dissolved in mixed acid and in a peroxyacid-nitric acid solution. Phosphorus reacts with ammonium vanadate and ammonium molybdate to form phosphovanadate. Arsenic is complexed with citric acid and phosphovanadate is extracted with 4-methyl-pentanone-2. Its photometric value is measured. 4 Reagents
4.1 Hydrochloric acid (density pl.19g/ml).
4.2 Nitric acid (density pl.42g/ml).
4.3 Perfluoric acid (density pl.67g/ml).
4.4 Nitric acid (1+5).
Hydrochloric acid-nitric acid mixed acid: hydrochloric acid (1) + nitric acid (4.2) (1+1). 4.5
Ammonium vanadate solution (2.5g/L)
Ammonium vanadate solution (150g/L).
4.8 Citric acid solution (500g/L).
Sodium nitrite solution (50g/L).
4.104-Methyl-pentanone-2.
Nickel solution: weigh 25g nickel nitrate C (Ni(NO,)·6HO). Place in a 250ml beaker, add water to dissolve, transfer to a 250ml volumetric flask, dilute to scale with water, and mix. This solution contains 20mg nickel in 1ml. 4.12 Chromium solution: Weigh 14g potassium dichromate and place in a 250ml beaker, add water to dissolve, transfer to a 250ml volumetric flask, dilute to scale with water, and mix. This solution contains 20mg chromium in 1ml. 4.13 Phosphorus standard solution
4.13.1 Weigh 0.6591g potassium dihydrogen phosphate (KH,PO.) that has been dried to a constant amount at 105C in advance, dissolve in water, transfer to a 1000ml volumetric flask, dilute to scale with water, and mix. This solution contains 0.15mg phosphorus in 1ml. 4.13.2 Take 20.00 ml of phosphorus standard solution (4.13.1) and place it in a 200 ml volumetric flask, dilute to the mark with water and mix well. This solution contains 15 μg of phosphorus in 1 ml.
5 Analysis steps
Approved by the Ministry of Machinery and Electronics Industry on June 26, 1992, and implemented on January 1, 1993
5.1 Sample quantity
Weigh 0.2500 g of sample.
5.2 Blank test
Perform a blank test with the sample. bzxZ.net
JB/T6326.12--92
5.3 Determination
5.3.1 Place the sample in a 125ml conical beaker, add 5~10ml hydrochloric acid-nitric acid mixture (4.5), heat to dissolve, add 10ml perchloric acid (4.3), evaporate and smoke until chromium is oxidized to hexavalent, add 2~3ml hydrochloric acid (4.1), evaporate chromium, repeat this process several times until yellow-brown gas stops emitting, cover the surface with blood, continue to heat to make the perfluoric acid smoke reflux steadily along the wall of the cup for 5~10min, cool, and add 15ml water to dissolve the salts. 5.3.2 If the test solution contains residues such as silica gel, filter it with filter paper, wash it with hot water 5~6 times, and then heat the filtrate to concentrate it to 10~15ml.
5.3.3 Add 15ml nitric acid (4.4), boil for 1-2min, add 5ml sodium nitrite solution (4.9), boil and remove nitrogen oxides. Cool to room temperature.
5.3.4 Add 5ml ammonium vanadate solution (4.6) and 7.5ml ammonium molybdate solution (4.7), and then place for 7min. Transfer the solution into a 125ml graduated separatory funnel, dilute to 50ml with water, and mix. Add 5ml citric acid solution (4.8), and mix. Immediately add 20.00ml 4-methyl-pentyl ketone-2 (4.10), shake for 30s, discard the aqueous phase after the two phases are separated, transfer the organic phase into a 3cm colorimetric dish, use the blank test color development solution as a reference, at a wavelength of 425m. Measure its absorbance and find the corresponding phosphorus amount from the working curve. Note: 1) When the temperature is 20℃, place it for 7 minutes, and the color will develop completely. When the temperature is lower than 20℃, extend the placement time appropriately. If the sample contains titanium and zirconium, add 1 to 2 drops of hydrofluoric acid. Increase the placement time to 1 hour. The color can develop completely. 5.4 Drawing of working curve
5.4.1 Nickel-chromium alloy
In 6 125ml triangular beakers, take 10ml of nickel solution (4.11) and 2.5ml of chromium solution (4.12), add 0.00, 1.00, 2.00, 3.00, 4.00, 5.00ml of phosphorus standard solution (4.13.2), and add 5ml of hydrochloric acid-nitric acid mixed acid (4.5). The following is carried out according to 5.3.1. to 5.3.4, taking the color developing solution without phosphorus solution as the reference, and measuring its absorbance. Draw the working curve. 5.4.2 Nickel-chromium-iron alloy
Weigh 6 portions of 0.060g pure iron (containing less than 0.001% phosphorus) and place them in 6 125ml triangular beakers. Add 7ml nickel solution (4.11) and 2ml chromium solution (4.12) respectively. Add 0.00, 1.00, 2.00, 3.00, 4.00, 5.00ml phosphorus standard solution (4.13.2). Add 5ml hydrochloric acid-nitric acid mixed acid (4.5), and proceed as per 5.3.1 to 5.3.4. Take the color developing solution without phosphorus standard solution as the reference solution, measure its absorbance, and draw a working curve. 6 Calculation of analysis results
Calculate the percentage of phosphorus according to the following formula.
Where: m---phosphorus content found from the working curve, g: sample size, g,
7 Allowable difference
ml×100
The difference in analysis results between laboratories should not be greater than the allowable difference listed in the following table. 30
Additional instructions:
Phosphorus content
0.005~0.010
>0.010~0.030
JB/T6326.12-—92
This standard was proposed and managed by the Shanghai Electric Science Research Institute of the Ministry of Machinery and Electronics Industry. This standard was drafted by the Shanghai Electric Science Research Institute of the Ministry of Machinery and Electronics Industry. The main drafters of this standard are Sun Huifang and Wu Haiyuan. Allowable difference
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