This standard specifies the method for determining the silicon content in nickel-chromium and nickel-chromium-iron alloys using the silicon-molybdenum blue photometric method. This standard is applicable to the determination of silicon content in nickel-chromium and nickel-chromium-iron alloys. Determination range: 0.10% to 2.00%. JB/T 6326.4-1992 Chemical analysis method for nickel-chromium and nickel-chromium-iron alloys Determination of silicon content by silicon-molybdenum blue photometric method JB/T6326.4-1992 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 Determination of silicon content by silicon-molybdenum blue photometric method
Subject content and scope of application
This standard specifies the method for determining the silicon content of nickel-chromium and nickel-chromium-iron alloys by silicon-molybdenum blue photometric method. This standard is applicable to the determination of silicon content in nickel-chromium and nickel-chromium-iron alloys. Determination range: 0.10%~2.00%. 2 Reference standards
GB1467 General principles and general provisions for chemical analysis methods of metallurgical products. 3 Method summary
JB/T6326.492
The sample is dissolved in mixed acid to convert silicon into soluble orthosilicic acid. At appropriate acidity, silicic acid reacts with ammonium tantalum to generate silico-molybdenum heteropoly acid, then the acidity is increased and in the presence of oxalic acid, it is reduced to silicon-molybdenum blue with ammonium ferrous sulfate, and its absorbance is measured. For nickel-based alloys with high silicon content, hydronitric acid can be added during sample dissolution to prevent the fusion of silicate. The coexisting elements in this method have no interference. 4 Reagents
4.1 Anhydrous sodium carbonate bZxz.net
4.2 Hydrochloric acid (density p1.19g/ml).
4.3 Nitric acid (density pl.42g/ml).
4.4 Hydrofluoric acid (density pl.15g/ml).
Sulfuric acid (density pl.84g/ml).
Nitric acid (1+2).
Hydrochloric acid-nitric acid mixed acid: hydrochloric acid (4.2) + nitric acid (4.3) + water (1+1+1). Sulfuric acid (1+1).
Sulfuric acid (1+3).
Urea solution (100g/L).
Boric acid saturated solution; 60g boric acid is dissolved in 1000ml hot water. Cool to room temperature. Ammonium molybdate solution (50 g/L).
4.13 Ammonium oxalate solution: weigh 30 g of ammonium oxalate and dissolve it in 1000 ml of sulfuric acid (4.9). 4.14
Ammonium ferrous sulfate solution (60 g/L): add 6 drops of sulfuric acid (4.8) to every 100 ml of solution. Nickel solution: weigh 0.10 g of pure nickel (purity greater than 99.95%), dissolve it in 12 ml of nitric acid (4.6), add 10 ml of urea solution (4.10), cool it and transfer it to a 100 ml volumetric flask, dilute it to the mark with water, and mix it. 4.16 Silicon standard solution.
4.16.1 Take silicon dioxide (99.99%) in a platinum crucible, burn it at 1000°C for 20 minutes, and transfer it to a desiccator to cool. Weigh 0.2143g and place it in a platinum crucible, add 5g of anhydrous sodium carbonate (4.1) and melt at 950C for 30min and cool. Place the crucible in a tetrafluoroethylene plastic beaker and add water to leach the molten block. Transfer the solution into a 500ml volumetric flask and dilute to scale with water. Mix well and immediately transfer the solution to a dry plastic bottle for storage. Approved by the Ministry of Machinery and Electronics Industry on June 26, 1992 and implemented on January 1, 1993. This solution contains 0.20mg silicon in 1ml.
JB/T6326.4-92
4.16.2 Transfer 50.00ml of silicon standard drop solution (4.16.1) and place it in a 200ml volumetric flask, dilute to scale with water and mix well. Immediately transfer the solution to a dry plastic bottle for storage. This solution contains 50μg silicon in 1ml. 4.16.3 Take 20.00 ml of silicon standard solution (4.16.1) and place it in a 200 ml volumetric flask, dilute with water to the mark and mix. Immediately transfer the solution to a dry plastic bottle for storage. This solution contains 20 μg of silicon in 1 ml. 5 Analysis steps
5.1 Sample amount
Weigh 0.1000 g of sample.
5.2 Blank test
Perform a blank test along with the sample.
5.3 Determination
5.3.1 Place the sample in a 100ml plastic beaker, add 10ml hydrochloric acid-nitric acid mixture (4.7) and heat in a water bath until the sample is completely dissolved. Cool to below 60°C, add 10 drops of hydrofluoric acid (4.4), mix well, let stand for 3 minutes, add 10ml urea solution (4.10), and then add 20ml acid saturated solution (4.11). Cool to room temperature, transfer the solution to a 100ml volumetric flask, dilute to the mark with water, mix well, and immediately pour the solution into a dry plastic beaker.
5.3.2 Take two portions of 10.00ml of the sample solution and place them in 100ml containers respectively. One portion is used as the color development solution and one portion is used as the reference solution. 5.3.3 Color solution: add 5 ml of ammonium molybdate solution (4.12), heat in a boiling water bath for 30 seconds, cool with running water, add 20 ml of ammonium oxalate solution (4.13), and immediately add 10 ml of ammonium ferrous sulfate solution (4.14). Dilute to scale with water and mix well. 5.3.4 Reference solution: add 20 ml of ammonium oxalate solution (4.13), 10 ml of ammonium ferrous sulfate solution (4.14), and then add 5 ml of ammonium aluminate solution (4.12), dilute to scale with water and mix well. 5.3.5 Transfer part of the solution into a 1 cm or 2 cm cuvette, use the reference solution as a reference, measure its absorbance at a wavelength of 665 nm on a spectrophotometer, and subtract the absorbance of the reagent blank. Find the corresponding silicon content from the working curve. 5.4 Drawing of working curve
Take 6 portions of 10 ml nickel solution (4.15) and place them in 6 100 ml volumetric flasks respectively. Add 0.00, 1.00, 2.00, 3.00, 4.00 and 5.00 ml silicon standard solution (4.16.2 or 4.16.3) in sequence. Proceed as in 5.3.3 to 5.3.5. Take the color developing solution without silicon standard solution as the reference solution, measure its absorbance and draw the working curve. 6 Calculation of analysis results
Calculate the percentage of silicon by the following formula:
Si(%)=
Wherein: m—the amount of silicon found from the working curve, g; V——total volume of test solution, ml;
V,—volume of test solution taken, ml;
—sample weight, g
7 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in the following table. Additional remarks:
Silicon content
0.10~0.50
>0.50~1.00
>1.00~2.00
JB/T 6326. 4-92
This standard was proposed and managed by the Shanghai Electric Science Research Institute of the Ministry of Machinery and Electronics Industry, and was drafted by the Shanghai Materials Research Institute of the Ministry of Machinery and Electronics Industry. The main drafters of this standard are Zhu Fuzhen and Fan Yi.
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