GB/T 4324.25-1984 Chemical analysis of tungsten - Inert gas fusion coulometric titration method for determination of oxygen content

GB/T 4324.25-1984 Chemical analysis of tungsten - Inert gas fusion coulometric titration for the determination of oxygen content GB/T4324.25-1984 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis method of tungsten
Methods for chemical analysis of tungsten The inert gas fusion -coulometric titration method far the de termination of oxygen content
This standard is applicable to the determination of hydrogen content in tungsten. Determination range: 0.0005～0.80%. This standard complies with (1467-78 "General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products", 1 Method Summary
UDC663.27:543
-274:546.21
GB 4324.25—84
In a carrier gas flow, place the sample in a graphite vortex that has been degassed at high temperature: that is, let low voltage and high current pass through the vortex to produce a commercial mixture, so that the sample melts, oxygen and carbon react to produce carbon dioxide, which is carried by the carrier gas flow into a 600℃ copper oxide converter and converted into carbon dioxide. Then the sample enters the absorption electrolytic cup and is absorbed by a perchloric acid solution with a pH of about 9.5. The produced oxygen ions lower the pH value of the solution. Electrolysis is carried out with a pulse current injected by the electrolyte to restore the pH of the solution to the original value. The oxygen content of the sample is calculated based on the pulse power consumed during electrolysis.
In the case of gas melting, the sample is heated by nitrogen and thermally decomposed to produce hydrogen and nitrogen, which do not interfere with the coulometric titration of carbon dioxide. 2 Reagents and materials
2.1 Copper oxide: in filamentous form, filled in the quartz cup of the copper oxide converter. 2.2 Materials and test materials for gas purification 2.3 Sodium carbonate: Powder, fill the bottom of the anode tank. 2.4 Cathode tank solution: Weigh 100g of the product chlorinated acid and 60ml of isocyanate, dissolve in 2000ml of water, put in a ground-mouth bottle for later use. 2.5 Anode tank solution: Weigh 5g of the product chlorinated acid, dissolve in 500ml of water, put in a ground-mouth bottle for later use. 2.6 Cathode tank solution: Weigh 5g of the product chlorinated acid, dissolve in 500ml of water, put in a ground-mouth bottle for later use. Perchloric acid and 3g sodium chloride are dissolved in 100ml water. A few drops of 5% silver nitrate solution are added and kept in a Moshan bottle for later use.
2.7 Perchloric acid wash solution (5%): Use to clean the electrode pool. 2.8
Xingyi uniform glass: Pattern 1 shows that it can be made of spectrally pure graphite electrode. National Bureau of Standards 1984-04-12 issued
1985-03-01 implementation
GF 4324.25--84
Figure! Stone
Tin foil: purity not more than 0.05m, oxygen content less than 50ppm. Argon: purity more than 99.99%, water content less than 5ppm. Glass wool. Fill and discard in the dust collector.
2.12 Platinum sample with known oxygen content
Instruments and equipment
3.1 Ball-impact heating combined oxygen meter, gas path carrier gas and its chemistry system, pulse heating furnace, oxidation conversion furnace, coulometric analyzer, etc. | |tt||The process of the production line is shown in Figure 2
（3192）
Figure 2 Schematic diagram of the process of the gas line
1 Gas cylinder: 2-call, 3-color change separation pipe, 4-hydrogen emulsification pipe! 5 (1, 5 (2), 5 (3)-five-lead phosphorus: 6-pressure gauge, 7【)7(2).7(3)-7(4)-needle 8 (1)8(2), 8 ()8(4)-respectively for degassing flow recorder, analytical flow display, oxygen screen flow meter, high oxygen flow meter; 9 (1), 9 (2), 9 (3), 9 (4) - electromagnetic 10 - pulse frying, 11 - filter, 12 - chemical conversion, [3 - split flow measurement + 14 - split flow attack, .15 - absorption electrolysis cup
The "decontamination and washing" gas path process is composed of a needle valve 7 (1), a flow meter 8 (1), a five-chemical phosphorus tube (2), an electromagnetic measurement 9 (1), an electromagnetic balance 9 (2), a pulse furnace 10, a medium magnetic 9 (3), and venting. When the pulse furnace is turned on or the graphite 20 volute degassing is avoided, it provides 85
GB4324.25 —84
21, mi of gas supply, flushing pulse juice, needle valve 7 (2) five phosphorus pipe 5 (3), solenoid valve 9 (2), pulse furnace 10, 1 magnet 9 (3), filter 11, copper oxide converter 12, flow rate 8 (2), through 14, 1 paste 9 (4), absorption electrolysis cup 16 discharge chamber, etc. constitute the "divide" gas flow: needle valve (3), flow meter (3), absorption electrolysis cup (top), venting, etc. constitute the "microscreen" "flow path" to protect the absorption liquid from contacting the atmosphere. The heating power of the pulse furnace should not be less than 10kw. Without adding a flux, the heating temperature should be able to melt the pigeon sample well. The copper oxide converter is shown in Figure 3. It can convert carbon oxide in the fluorine gas flow into carbon monoxide quantitatively when heated to 600℃. The steam carrier population
cut out
protection shop
Huanghuawang
3 oxidation regulation converter
Shencang Taoding Xunlu seeks the schematic diagram as shown in Figure 4.wwW.bzxz.Net
The pulse current is the standard for the mountain charge and discharge circuit. When the charge and discharge capacitor in the circuit is charged to a certain level, the electrolytic electrode is connected, and the electric current is abandoned! It can also be 4, in the form of an electrolytic pulse through the absorption liquid, and its electric process is relatively low. 0.5×10-5g oxygen, 3.2 turbine: 150mm, carbon grinding wheel. 3.3 Use high quality alloy grinding body,
pressure cylinder and port power regulating valve.
GB4324.25-84
Figure 4 Coulomb titration circuit diagram
1 Anode [including dew, skin ion plate, crane electrode (cathode)], 2 Resistor (cathode), 3 Multi-electrode (silver fluoride) Chemical microelectrode: 4-H electric shuttle: 5-control circuit: 6-pulse frequency control circuit: 7-charging circuit, 8-counting display circuit, 9-constant current
4.1 The block sample is gently rubbed on the carbide grinding wheel, and then it is granulated into particles with a diameter of about 5mm and a mass of 0.5~!g on a clean carbide mortar. It is washed with carbon chloride, taken out and blown with cold air, and weighed. After the sample is treated, it should be tightly wrapped with tin foil or nickel foil weighed in advance, and then the total mass of the sample and tin foil or nickel foil is weighed.
Analysis steps
5.1 Determination of quantity
When analyzing, three samples are weighed for appropriate measurement. The measurement should not be too small. The allowable difference between laboratories is taken, and the average value is taken. 5.2 Sample quantity
Weigh the sample quantity according to the table
0.0010- 0,010
0.010 ~0. 10
0.10 -0.80
5.3 Preparation of the instrument
Sample mouse, s
2.500-2.000
2.000~1.000
0. 5000 ~0.1000
0.1000~0.050
Sample
5,3.1 Open the oxygen main valve. Adjust the pressure regulator so that the pressure gauge indicates about 1kg/cm2, adjust the needle valve 7 (3) so that the argon screen 87
GB4324.25---84
flow rate is 200ml/beatin. Set the four-way split to the 1:1 position, connect the power supply of the electromagnetic 9 (4) to make it produce a venting state, and adjust it to a needle state. ? (2) The air flow of the air distribution system is flushed at 40oml/min for about 30min. 5.3.2 The copper oxide converter is heated and kept at 100℃. Connect the power supply of the coulometric analyzer and let the coulometric analyzer stabilize. 5.4 Calibration of the instrument
5.4.1 Adjust the expansion valve 7 (2) to make the new flow rate of the distribution screen to 150ml/min, close the power supply of the solenoid valve 9 (4), and let the analytical air flow enter the suction cup. Determine the background blank of the air flow, and count 1 electrolytic pulse per minute. Repeat the end point reversal of the pH circuit several times to make the pH of the receiving liquid about 9.5. At the same time, adjust the counting frequency of the pulse current. Make the average pulse flow passing through the absorption liquid 1 or 2.
5.4.2 Use a constant current source to calibrate the electrolytic pulse current of coulometric titration, so that the power from the constant current source is reversely passed into the absorption cup 1, and the pulse current value displayed when the electrolysis is stopped is between 166 and 170, then the power of each pulse value is equivalent to 0.6 × 10-oxygen.
5.4.3 The same analysis conditions and steps are used to determine the pigeon sample with known oxygen content, and the analysis results should be within the allowable difference. 5.5 Degassing and blank test of graphite crucible
5.5.1 Change the gas flow from the analysis process to the degassing flow, turn on the pulse heating furnace, turn off the power, put in the graphite furnace, close the protection, adjust the pulse heat load to 0.2~0.5V higher than the heating output pressure of the new sample, and heat and degas for 45s at high temperature. After 10s, heat and degas for 45s again to remove the gas on the surface of the graphite and the electrode. 5.5.2. After degassing, under the analytical conditions that are consistent with the sample, measure the vacuum in the vehicle or tin box, and repeat the measurement for several times to take the average value. Generally, the required vacuum value should not exceed 10 pulses, and the fluctuation should not exceed 3 counts.
5.6 Determination of the sample
5.6.1 After degassing and measuring the vacuum value, make the micro-airflow the degassing process. Under the selected sample heating conditions, heat again for 15s. After stopping heating for about 5s, quickly put the sample into the medium. 5.6.2 Immediately convert the gas path to the analytical process and adjust the heating load. The heating voltage of the powder sample shall not be less than 10.55V, the thermal current shall be above 750A, and the heating shall be carried out for 24s. The heating voltage of the block sample shall not be less than 6.0V, the heating current shall be above 800A, and the heating shall be carried out for 245. The sample melts well. At this time, the thermal current will increase slightly, and there is no need to adjust the heating load. 5.6.3 When the sample is heated, the absorption electrolysis time starts to be calculated. The gas to be measured is carried out by the carrier gas, converted by copper oxide, and enters the absorption cup. The analyzer performs electrolysis and automatically counts the electrolysis pulse current. The absorption electrolysis lasts for 3 minutes. The system returns to the original background voltage and the pulse current count displayed on the digital tube is read. 5.6.4 For graphite samples, one new sample is separated every time. For powdered samples in the Zhou stone container, proceed according to 5.6.1 to 5.6.3. Four samples can be continuously tested.
6 Calculation of analysis results
Calculate the oxygen percentage according to the following formula:
0 (%)
(AB) ×0.5× 10-6
Wherein: A is the number of electrolytic pulse current counts obtained when analyzing the sample; ri
B is the average number of electrolytic pulse current counts obtained when analyzing the crucible or tin foil in an empty sweep; g is the mass of oxygen in a sample, g
0.5×10-1 pulse flow phase. 1 Allowable difference
: The difference between the analysis results of the laboratory shall not be greater than the allowable difference listed in Table 2. 88
Additional instructions:
0.0005~*20.0010
0.0010~0.0040
0.0040 -0.0100
0.010~0.050
0.050 ~≤0.100
0.100-0.800
GB 4324.2584
This standard was proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard was drafted by Zhuzhou Cemented Carbide.
Allowable deviation
The main drafters of this standard are Wang Shuifa and Chen Lanying. From the date of implementation of this standard, the Ministry of Metallurgical Industry Standard YB895-77 "Chemical Analysis Method for Tungsten" will be invalidated.
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