GB/T 4324.2-1984 Chemical analysis of tungsten - Potassium iodide-strychnine photometric method for the determination of bismuth
Some standard content:
National Standard of the People's Republic of China
Chemical analysis methods of tungsten
Potassium iodide-brucine photometric method for the determination of bismuth content Methods for chemical analysis of tungsten The potassium iodide-brucine photometric method for the determination of bismuth content LDC 669.27 1543
42-546.87
GB 4324.2— 84
This standard is applicable to the determination of bismuth content in tungsten powder, tungsten bar, tungsten monoxide, tungstic acid, and tungsten monoxide. Determination range: 0,00008-0.0040%. This standard complies with CB1467-78 "General Principles and General Provisions for Chemical Analysis Methods for Metallurgical Products". 1 Method Summary
The sample is dissolved with sodium hydroxide, tungsten is complexed with citric acid, and α (III) potassium iodide is dissolved in sulfuric acid to form a "unit complex", which is taken up with chloroform and its absorbance is measured. 2 Reagents
2.1 Chloroform
2.2 Sulfuric acid (1+3.)
2.3 Sodium hydroxide solution (40%), high-grade pure
2.4 Citric acid (C.HsO,·H,O) solution (50%)
2.5 Sulfur solution (10%)
2.6 Potassium iodide solution (10%), stored in a brown bottle
2.7 Strychnine (CHgO,N,·H,O) solution (1%): Weigh 1g of strychnine and dissolve it with citric acid solution (20%) and dilute it to 100ml, mix it in a brown bottle
2.8 Phenolyl ethanol solution (1%) ||t t||2.9 Bismuth standard solution
2.9.1. Weigh 0.1000g of metallic bismuth (99.99% or more), place in a 200ml beaker, add 10ml of nitric acid (specific gravity 1.42), heat to dissolve, transfer to a 1000ml volumetric flask, cool to room temperature. Dilute to scale with water and mix. This solution contains 100±g bismuth in 1ml. 2.9.2. Transfer 10.00ml of sharp standard solution (2.9.. 1), put it in a 200ml volumetric flask, dilute it to the mark with nitric acid (1+9), and mix it. This solution contains 5μg bismuth per ml.
2.9.3 Take 10.00ml of the bismuth standard solution (2.9.1), put it in a 500ml volumetric flask, dilute it to the mark with dichloroacetic acid (1+9), and mix it. This solution contains 2μg bismuth per ml.
3 Samples
3.1 The tungsten bar should be crushed and passed through 12 0 self-sieve. 3.2 After weighing the tungsten powder and tungsten bar, place them in a porcelain evaporator 4, burn them in a high-temperature furnace at 300~500℃, slowly raise the temperature to 750℃, and stir them frequently with a glass rod to completely oxidize the sample, take them out, place them in a desiccator 1 and cool them to room temperature. 4 Analysis steps
Determination quantity
National Bureau of Standards 1984-04-12 Issued
1985-03-01 Implementation
GB 4324.2--84
Take the middle value.
When analyzing, three samples should be weighed for determination, and the measured value should be within the allowable difference in the room. 4.2. Sample quantity
4.2.1 Weigh 0.5000~3.000g of tungsten trioxide, pigeon acid, and ammonium paratungstate. 4.2.2 Weigh 0.5000~2.500g of tungsten powder and pin. 4.8 Blank test
Carry out a blank test with the sample.
4.4 Determination|| tt||4.41 Place the sample (4.2) in a 150ml beaker, add a small amount of water to moisten it, add sodium hydroxide solution (2.3) according to Table 1, heat it, and remove it after the sample is completely dissolved. Wash the surface and the cup wall with water, and add citric acid solution (2.4) according to Table 1 while it is hot under constant shaking, mix it, and let it cool to room temperature.
4.42 Add 1~2 drops of acetyl alcohol solution (2.8), sulfuric acid (2.2) and sodium hydroxide solution (2.3) to adjust the test solution to red. Table 1
Sample mother, 5
Sodium hydroxide solution (2.3), ml
Citrate phosphorus solution (2.4), ml
4.3 Add 6ml sulfuric acid (2.2) under constant shaking, dilute with water to about 40ml, heat on a low-temperature electric stove, keep it slightly boiling for more than 5min: (be careful not to splash, keep the volume not less than 100ml), and cool to room temperature. 4.4.4 Add 5ml sulfuric acid solution (2.5), mix well, add 5ml potassium iodide solution (2.6), transfer to a 125ml separatory funnel, control the solution volume to 50ml, mix well, and add 5ml caustic soda solution (2.7) under constant shaking (note that the test solution should not be turbid, otherwise the result will be abnormal).
Add 10.00ml chloroform (2.1), shake for 2min, wipe the neck of the funnel and insert cotton wool, let stand to separate, filter the organic matter into a 3cm colorimetric funnel, and measure its absorbance at a wavelength of 460nm using dichloromethane (2.1) as a reference on a spectrophotometer.
4.4.7 Subtract the absorbance of the hollow convex made with the sample. Find the corresponding bismuth amount from the curve in 1. 4.5 Drawing of the working curve
4.51 Take 0.00, 0.50, 1.00, 2.00, 3.00, 4.00, 5.00ml of blanket standard solution (2.9.2 or 2.9.3) 4.5.2 and place them in a group of 125ml separatory funnels, dilute with water to about 15ml, add 1-2 drops of phenolic alcohol solution (2.8), and adjust the test solution to red with sodium hydroxide solution (2.3). .5.3. Under constant perturbation, add 6 ml sulfuric acid (2.2), 5 ml sulfuric acid solution (2.5), mix, add 5 ml potassium iodide solution (2.6), control the solution volume to 50 ml, mix, add 5 ml thiazine solution (2.7) under constant shaking, and proceed as in 4.4.5 to 4.4.6, measure its absorbance, and subtract the absorbance of the reagent blank. Draw a working curve with the amount of bismuth as the horizontal axis and the absorbance as the vertical axis.
5 Calculation of analysis results
Calculate the percentage of bismuth according to the following formula:
Bi (%)=
Wherein, m—the amount of bismuth found from the T curve, m
—the amount of sample, g.
Additional allowable difference
GB 4324.2--84
The difference in the analysis results between laboratories should not exceed the allowable range shown in Table 2. Table 2
T.00008--f.60026
0.00020~0.00080
-0.0015 ~0,0540
Additional remarks:
This standard was proposed by the Ministry of Metallurgy of the People's Republic of China. This standard was drafted by Zhuzhou Cemented Carbide Factory.
This standard was drafted by Li Chang.
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