GB/T 4324.12-1984 Chemical analysis of tungsten - Determination of silicon content by the molybdenum blue chloride photometric method
Some standard content:
National Standard of the People's Republic of China
Chemical analysis method of tungsten
Methods for chemical analysis of tungstenThe chlorination - molybdenum blue photometricmethod for the determination of silicon contentUDC 669.27 :543
-42:546.28
GB 4324.12--84
This standard is applicable to the determination of silicon content in pigeon powder, tungsten bars, tungsten oxide, tungstic acid and ammonium paratungstate. Determination range: 0.00050.030%. This standard complies with GB1467-78 "General Principles and General Provisions of Chemical Analysis Methods for Metallurgical Products". 1 Method Summary
The sample is nitrided to separate the main tungsten, the residue is melted with sodium carbonate, leached with water, tartaric acid is used as a complexing agent in an acidic solution, silicon and ammonium molybdate are reacted in oxalic acid-sulfuric acid mixture to form silico-molybdenum yellow heteropoly acid, extracted with n-butanol; tin chloride is used to reduce molybdenum blue, and its absorbance is measured.
2 Reagents and Materials
2.1 n-Butyl alcohol.
2.2 Hydrochloric acid (1 + 1).
2.3 Hydrochloric acid (1 + 3).
Tartaric acid solution (25%), stored in a plastic bottle. 2.4
2.5 Ammonium salicyclic acid solution (10%), stored in a plastic bottle. 2.6 Stannous chloride solution (5%): Weigh 0.5g tin chloride (SnCl, ·2H,0), place in a 50ml beaker, add 5ml hydrochloric acid (specific gravity 1.19), heat to dissolve, dilute with water at a rate of 10ml, and prepare when needed. 2.1
bottle.
Oxalic acid-sulfuric acid mixture: Mix 150ml oxalic acid solution (5%) with 100ml sulfuric acid (1+3), stir, add to plastic sodium carbonate solution (5%), and place in a plastic bottle. Single distilled water (this water is used in this method). 2.10 Silicon standard solution
2.10.1 Weigh 0.1069g of silicon dioxide (reference reagent) previously calcined at 900℃, place in a tantalum crucible, add 4g of anhydrous sodium carbonate, melt at 900～95℃ until clear, cool, soak in hot water in a plastic cup, clean the crucible, cool, transfer to a 500ml volumetric flask, dilute to scale with water, and mix. This solution contains 100μg silicon per ml. Store in a plastic bottle. 2.10.2 Transfer 25.00ml of silicon standard solution (2.11.1), place in a 500ml volumetric flask, dilute to scale with water, and mix. This solution contains 5μg per ml. Store in a plastic cup. 2.11 pH test paper (pH0.50～5.0).
Chlorination device, see the figure below
National Bureau of Standards 1984-04-12 issued
1985-03-01 implementation
4 Sample
GB4324.1284
:! (age): 2-sulfurization oxidizer (containing sulfuric acid), 3-sharp hole flow plate 4-tube, 6-buffer bottle, 6-sulfuric acid washing bottle, 7-body distributor 8-22mm×2mm×65umm) 7, 9-beautification, 10-thermocouple, 1! Resistance furnace temperature controller
That is, the poem powder review and avoid 120 door screen.
.2 Press the point, take 0.10001.00g of powder and casting in advance; burn and oxidize into trioxide in the quartz tube of 750℃ chlorination furnace: small
. Name area! Take 0.10~1.000g of ammonium paraffinate and pigeon acid and place them at the mouth of the quartz tube for decomposition, then push them into the 600℃ high temperature slow burning
technology, 4 continents
5 Analysis steps
5.1 Determination quantity
Take a sample of the diseased part for measurement, the measurement delay value should be within the room allowable tolerance, and take its half mean. 5.2 Sample quantity
connection! Test.2 minus 4.3,
sample weight, g
6.60:5-0-930
0,0036~0.0070
-1, 0070 --0.10
-0,H -[,015
-n.015-0.63
5.3 Blank testbzxZ.net
Perform blank test on random samples.
GB 4324. 12—84
5.4 Determination
5.4.1 Spread the sample (5.2) evenly! Push the boat into the quartz tube of the chlorination furnace preheated to 750-780℃, pass 5% dry chlorination oxygen gas, the gas flow rate is about 30ml/min (the flow scale of the sharp orifice flow indicator is corrected by the oxygen scale micro-flow rate), after the chlorination is completed, take it out and cool it.
5.4.2 Add 1ml sodium carbonate solution (2.8), dry it under an infrared lamp, and then melt the whole platinum boat at 900-950℃ for 5min, take it out and cool it, soak the melt in 2-3ml hot water, heat it under an infrared lamp for 5min, and cool it. 5.4.3 Transfer the solution to a 125 ml separatory funnel, adjust the pH to 2.5 with hydrochloric acid (2.3) [check with pll test paper (2.11)], add 1 ml excess, add 2 ml ammonium sulfate solution (2.5), dilute with water to 15 ml, mix, and the effect is 15 ml. 5.4.4 Add 2.5 ml tartaric acid solution (2.4), 6 ml oxalic acid-sulfuric acid mixture (2.7), 5 ml sodium sulfate (2.2), and mix each reagent. Add 13 ml 1-ethanol ( 2.1), shake for 1min, keep the mixture under the cover, transfer water to the separated liquid, add 6ml of n-butyl alcohol (2.1), shake for 1min, let stand, remove the aqueous phase, combine the organic phase in 25ml colorimetric tank, dilute to the mark with ethanol, mix, add 2 drops of chloroform solution (2.6), 5.4.5 Transfer part of the solution (5.4.4) into a 0.5cm colorimetric tank, use n-butyl alcohol as reference, and measure its absorbance at 800mm of the spectrophotometer.
5.4 .6, minus the absorbance of the sample. Save the corresponding value from the curve. 5.5 Drawing of working curve
Put 0.00, 0.50, 1.50, 3.00, 6.00, 9.00 ml of silicon standard solution (2.10.2) into 125 ml liquid funnel, add 1 ml of hydrochloric acid (2.3), dilute to about 10 ml with water, mix, add 2 ml of ferric sulphate solution (2.5), dilute to 15 ml with water, mix, and place for 15 min. The following is carried out according to 5.4.4~5.4.5, measuring its absorbance and subtracting the absorbance of the reagent air. With the amount as the horizontal axis and the absorbance as the vertical axis, draw a working curve. Calculation of analysis results
The optimal content is calculated as follows
In the formula: mi-——silicon mouse obtained from the working line, sample amount, g.
7 Allowable difference
The difference in analysis results between laboratories should not be less than the allowable difference listed in Table 2. Table 2
0,0005 --0.0015
>0. 0015 ~0. 0025
20. 0025 ~ 0.0040
>0.004 ~0.009
0.009 -0.012
20.012 ~0,018
>0.018 ~0.030
Additional Notes:
GB4324.12--84
This standard was proposed by the Ministry of Metallurgical Industry of the People's Republic of China. Zhuzhou Cemented Carbide Co., Ltd. was responsible for drafting. This standard was drafted by Zhuzhou Cemented Carbide Co., Ltd. The main drafter of this standard is Shi Ruiping.
From the date of implementation of this standard, the former Ministry of Metallurgical Industry Standard YB895-77 "Chemical Analysis Method for Tungsten" shall be used as the standard. 38
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