This standard is applicable to the determination of total carbon content in carbides of tungsten, titanium, niobium, tantalum, chromium, molybdenum, vanadium, zirconium and hafnium, mixed powders of these carbides and bonding metals (without lubricants and binders), and pre-sintered or sintered cemented carbides of all grades produced from these carbides. The determination range is above 4.00%. This standard complies with GB 1467-78 "General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products". This standard is equivalent to the international standard ISO 3907-1977 "Cemented Carbide-Determination of Total Carbon-Gravimetric Method". GB/T 5124.1-1985 Chemical Analysis Method for Cemented Carbide-Determination of Total Carbon by Gravimetric Method GB/T5124.1-1985 Standard Download Decompression Password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis methods of hardmetals
Gravimetric method for the determination of total carbon content
UDC 669.018.25
: 543.21 : 546
GB5124.1---85
This standard is applicable to the determination of total carbon content in carbides of tungsten, titanium, niobium, molybdenum, chromium, zirconium, vanadium, zirconium and hafnium, mixed powders of these carbides and binder metals (without lubricants and binders) and pre-sintered or sintered hardmetals of all grades produced from these carbides. The determination range is above 4.00%.
This standard complies with GB146778 "General Principles and General Provisions of Standards for Chemical Analysis Methods of Metallurgical Products". This standard is equivalent to the international standard ISO3907-1977 "Determination of total carbon content in cemented carbide - Gravimetric method". 1 Method Summary
In a high-temperature pure oxygen flow, carbon is oxidized to carbon dioxide, and a flux is added if necessary. The generated carbon oxide is carried by oxygen to a constant-volume absorption bottle and absorbed by caustic soda asbestos. The increase in caustic soda asbestos is measured as the amount of carbon oxide generated.
2NaOH + CO2
2Reagents
2.1Oxygen: purity greater than 99%.
2.2Magnesium perchlorate, anhydrous.
+Na2C0, + H,0
2.3Flux, such as metallic tin, metallic copper or copper oxide, metallic iron, etc. 2.4Caustic soda wool: 10-20 mesh, carbon dioxide absorption capacity not less than 30%, avoid contact with air as much as possible. 2.5Asbestos.
3 Instruments
3.1 The instrument consists of an oxygen vapor source, an oxygen purification device, a tubular electric furnace, a drying device and a carbon dioxide absorption device. The equipment and devices are connected in sequence with connecting pipes, and the entire system should be leak-proof. See the diagram for a schematic diagram of the instrument!
Instructions for use: The international standard is lubricant-free. Issued by the National Bureau of Standards on April 24, 1985
Implemented on February 1, 1986
GB 5124.1-85
1-Oxygen source, 2-Flow meter: 3-Tube electric furnace, 4-Drying and purifying oxygen device, 5-Electric furnace, 6-Combustion tube, ?-Blood, 8-Asbestos wool plug: 9-Drying bottle 10, 11 Absorption bottle 3.1.1
Oxygen (2.1) source: with pressure regulating valve. 3.1.2 Flow meter.
3.1.3 Tubular electric furnace: with non-porous combustion porcelain tube, filled with platinum asbestos, furnace temperature maintained at 625℃. 3.1.4
Separated.
Drying and oxygen purification device: filled with magnesium perchlorate (2.2) and caustic soda asbestos (2.4), with glass wool or quartz fiber in the middle. 3.1.5 Electric furnace: with suitable temperature control device, furnace temperature can reach 1350℃. 3.1.6 Combustion tube: made of non-porous refractory material, with an inner diameter of 18~30mm and a length of at least 650mm, so that the temperature at the end of the combustion tube will not exceed 60℃ during operation.
3.1.7 Boat blood: made of refractory material, should be pre-treated in oxygen flow at test temperature for 10m in, or burn at 800-1000℃ for 1h. Boat IIIl should have appropriate size, for example 80-100mm long, 12-14mm wide, 8-9mm deep. The treated boat III should be stored in a desiccator, and the ground surface and cover of the desiccator should not be greased. 3.1.8 Asbestos wool: quartz fiber or burned. 3.1.9 Hand drying bottle: filled with magnesium perchlorate (2.2). 3.1.10 Absorption bottle: filled with caustic soda asbestos (2.4) and a small amount of magnesium perchlorate (2.2). The absorption bottle is shown in Figure 2. Figure 2
1-Caustic soda asbestos (2.4) 2-Magnesium perchlorate (2.2); 3-Quartz fiber or glass wool
1Absorption bottle: connected to 10 in reverse.
GB 5124.1—85
3.1.12 Hook: Made of heat-resistant metal wire with a carbon content of less than 0.05%, with a diameter of about 3mm and a length of about 50~60mm4 Sample
In a mortar that will not change the sample composition, grind the laboratory sample into powder and pass it through a 0.18mm sieve. 5 Analysis steps
5.1 Safety measures
When using magnesium perchlorate (2.2), in order to prevent possible explosion, the reagent should be avoided from contacting with organic matter, and special attention should be paid to it at other times.
5.2 Determination quantity
When analyzing, one or three samples should be weighed for determination. 5.3 Sample quantity
For a sample containing about 0.03g of carbon, the accuracy should be 0.0001g. 5.4 Blank test
Each determination value should be blanked with the sample. 5.5 Determination
5.5.1 Adjust the temperature of the combustion zone to 1200-1350℃ according to the properties of the sample, check the gas tightness of the instrument and the oxygen purification effect, and pass oxygen at a rate of 300-500ml/min for 1U-15min according to the point diameter of the combustion tube. Remove the absorption bottle (10), cool it to room temperature, weigh it to an accuracy of 0.0001g, and put it back to its original place.
5.5.2 According to the properties of the sample, if necessary, evenly cover the sample (5.3) in boat III with 0.2-1.0g of flux. 5.5.3 Open the combustion tube 11 at the oxygen inlet end, use the hook (3.2) to push the sample (5.3) into the high temperature part of the combustion tube, quickly plug the plug and pass oxygen at a flow rate of 300-500 ml/min, and continue to pass oxygen for 10-20 minutes to oxidize the sample and completely remove the carbon monoxide from the combustion tube and the drying bottle. wwW.bzxz.Net
5.5.4 Close the piston of the absorption bottle (10), immediately remove it from the instrument, cool it to room temperature, open and quickly close the piston to balance the force, and then weigh it to the nearest 0.0001g. It is recommended to visually inspect the melt in the boat to verify that the combustion is complete. The amount in the absorption bottle is the amount of carbon monoxide absorbed (m2). 6 Calculation of analysis results
Calculate the carbon percentage according to the following formula:
C (%) = 0.2729 × (mz=m)x 100ma
ti: m,-
Carbon dioxide amount measured by empty test, g
Carbon dioxide amount measured by burning sample, g; mo——sample position, g,
7Allowance
——""Conversion factor for converting carbon dioxide into carbon. ...The extreme difference of one or three independent measurement results shall not be greater than the allowable values ​​listed in the following table: Total
4.00~10.00
: Allowable difference of one independent measurement result
Allowable difference of three independent measurement results
GB5124.1-85
The arithmetic mean of qualified measurement values ​​shall be the final result. Additional remarks:
This standard was proposed by China Nonferrous Metals Industry Corporation. This standard was drafted by Zhuzhou Cemented Carbide Factory. The main drafters of this standard are Lan Xingji and Wang Jishen. 171
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