JB/T 7948.10-1999 JB/T 7948.10-1999 Chemical analysis methods for melting fluxes Combustion-coulometric method for determination of carbon content JB/T7948.10-1999 Standard download decompression password: www.bzxz.net

JB/T 7948.10-—1999
This standard is equivalent to F0CT22978.1~22978.10-78 "Methods for chemical analysis of melting flux". This standard is a revision of JB/T7948.10-95 "Methods for chemical analysis of melting flux - determination of carbon content by combustion-coulometric method". During the revision, only editorial changes were made to the standard, and its technical content remained unchanged. This standard replaces JB/T7948.10-95 from the date of implementation. This standard is proposed and managed by the National Welding Standardization Technical Committee. Who drafted this standard: Harbin Welding Research Institute. The main drafters of this standard: Lin Kegong and Bai Shuyun. 386
1 Scope
Standard of the Machinery Industry of the People's Republic of China
Methods for chemical analysis of melted welding fluxes
Determination of carbon content by combustion-coulomb method
Methods for chemical analysis of melted welding fluxesThe direct combustion-coulomb methodfor determination of total carbon contentThis standard applies to the determination of carbon content in melted welding fluxes. Determination range: 0.01%~0.05%. JB/T 7948.10--1999
Replaces JB/T7948.10-95
This standard complies with GB/T1467-1978 "General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products". 2 Referenced Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T1467-1978 General Principles and General Provisions of the Standard for Chemical Analysis Methods of Metallurgical Products 3 Method Summary
This method is based on the combustion of the sample in a tube furnace with oxygen, and the generated carbon dioxide is absorbed by a strontium chloride solution (pH-10), the pH value of the solution changes, and then electrolysis is carried out with a certain pulse of electricity. The amount of electricity required to cause the neutralization reaction of the absorption liquid is only related to the amount of dioxide, and the amount of electricity measured by the coulometer is converted into the percentage of carbon. When the flux is heated to 1300℃, silicon fluoride and carbon dioxide evaporate together. In order to absorb silicon fluoride, a circular column filled with weak base anion exchange resin can be used to precipitate silicon fluoride on the resin surface and hydrofluoric acid is absorbed. 4 Reagents
4.1 Oxidation pot (flux): burn at 800℃ for 4~~5h. 4.2 Anion exchange resin (701# weak base 330): soak in water for 24h before use, and then rinse with water several times. 4.3 Absorption solution: Weigh 50g potassium chloride and 50g strontium chloride (SrCl2·6H0) and dissolve them in appropriate amount of water, and then dilute to 1000mL. 4.4 Auxiliary solution: Weigh 50g potassium fluoride and 50g potassium ferrocyanide [K, Fe(CN)·3H.0] and dissolve them in appropriate amount of water, and then dilute to 1000mL.
5 Instrument
The carbon determination device is shown in Figure 1.
Approved by the State Bureau of Machinery Industry on June 24, 1999, and implemented on January 1, 2000
6 Test sample
JB/T7948.10-1999
1-Oxygen cylinder: 2-pressure gauge, 3-absorber (filled with caustic soda asbestos); 4-tube furnace, 5-porcelain boat (first calcined at 1300℃): 6-porcelain tube (inner diameter is 20-22mm, length is 650-750mm), 7-absorber [filled with anion exchange resin (4.2)], the upper and lower parts of the absorber are equipped with red test papers. If the upper test paper turns blue, it means that the anion exchange resin has failed and the hydrochloric acid has not been absorbed. The anion exchange resin should be replaced, and the absorbent of the coulometric analyzer should be replaced at the same time. 8-coulometric analyzer Figure 1 Carbon determination device diagram
The sample should pass through a 200-mesh sieve. Pre-bake at 105~110℃ for 1h, place in a desiccator and cool to room temperature. 7 Analysis steps
7. 1 Determination quantity
Three samples should be weighed for determination during analysis and the average value should be taken. 7.2 Sample quantity
Weigh 0.5000g of sample.
7.3 Determination
Put the sample (7.2) in a porcelain boat, add 1~2g of copper oxide flux (4.1), send it to the highest temperature of the porcelain tube, immediately plug the porcelain tube, pass oxygen combustion for 2min, and then operate according to the coulometric analyzer operating procedures to measure its readings. 8 Calculation of analysis results
Calculate the percentage of carbon based on the measured readings. 9 Allowable deviation
The difference between parallel determination results should not be greater than the allowable difference listed in Table 1. Table 1 Allowable difference
0. 01~0. 02bzxZ.net
>0. 02~0. 05
Allowable difference
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