This standard specifies the method for determining the amount of tin in silver tin oxide indium oxide electrical contact materials. This standard is applicable to the determination of the amount of tin in silver tin oxide indium oxide electrical contact materials. Determination range: 3.00% to 10.00%. JB/T 7777.1-1995 Silver tin oxide indium oxide electrical contact material chemistry JB/T7777.1-1995 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Chemical analysis method of silver oxide, tin oxide, indium contact material Iodine titration method for determination of tin content
1 Subject content and scope of application
This standard specifies the determination method of tin content in silver oxide, tin oxide, steel contact material. JB/T7777.1—1995
This standard is applicable to the determination of tin content in silver oxide, tin oxide, indium contact material. Determination range: 3.00%~10.00%. 2 Reference standards
JB4107.1—85
3 Principle of method
General principles and general provisions of chemical analysis method of electrical contact material The sample is decomposed with sulfur-nitric acid mixed acid, iron is used as a carrier, and ammonium hydroxide is added to make tin and iron form a coprecipitate and separate from the silver matrix. Then it is melted with sodium peroxide, leached with hot water, and tetravalent tin is reduced to divalent tin with aluminum foil. Starch is used as an indicator and titrated with potassium iodate standard solution until the solution appears light blue as the end point.
4 Reagents
Ammonium chloride (solid).
4.2 Sodium peroxide (solid).
Aluminum sheet (99.5% or more).
Mixed acid: 3 volumes of sulfuric acid (p1.84 g/mL) mixed with 2 volumes of nitric acid (p1.42 g/mL). 4.4
Hydrochloric acid (p1.19 g/mL).
Ammonium hydroxide (p0.90 g/mL).
Ammonium hydroxide (5+95).
Ferric trifluoride solution (100 g/L).
Sodium fluoride solution (10 g/L).
4.10 Saturated sodium bicarbonate solution.
Potassium iodate standard solution: weigh 0.6010g of standard potassium iodate that has been dried at 105℃ for 1h and cooled, dissolve in water, add 5g potassium iodide and 25mL sodium hydroxide solution (2g/L), stir to dissolve, transfer into a 1000mL volumetric flask, dilute to scale with water, and mix well. Each milliliter of this solution is equivalent to 0.0010g of tin.
4.12 Starch solution (10g/L): weigh 1g of soluble starch, add 5mL of water and stir, add 100mL of boiling water, boil, and cool. 5 Equipment
High temperature furnace.
6 Analysis steps
6.1 Test material
Approved by the Ministry of Machinery Industry on October 9, 1995
Implemented on January 1, 1996
JB/T 7777.1-1995
Weigh about 0.5g of test material, accurate to 0.0001g. 6.2 Blank test
Carry out a blank test with the test material.
6.3 Determination
6.3.1 Place the test material (6.1) in a 200mL beaker, add 15mL of warm acid (4.4), cover with a watch glass, and heat to decompose the test material. When there are no small bubbles, shake twice, continue heating until thick white smoke appears, and cool. Rinse the watch glass and the wall of the cup with water to make the test solution volume about 50mL. 6.3.2 Add 5 mL of ferric chloride solution (4.8) and 5 g of ammonium chloride (4.1), stir, and neutralize with ammonium hydroxide (4.6) until the silver precipitate is dissolved and 10 mL is in excess. After most of the precipitate has fallen, filter it with a rapid qualitative filter paper, wash the beaker and the precipitate with ammonium hydroxide (4.7) until there is no silver ion in the filtrate. After the filtrate is acidified, check it with sodium chloride solution (4.9). Discard the filtrate. 6.3.3 Place the precipitate together with the filter paper in an iron crucible, ashed on an electric furnace, and then move it into a 700℃ high-temperature furnace to burn for 15 minutes, take it out and cool it. Add 4 g of sodium peroxide (4.2) and stir it with a glass rod. Put it into a 700℃ high-temperature furnace to melt for 5 minutes, shake the crucible once, melt it for another 5 minutes, take it out and cool it.
6.3.4 Soak it in the original beaker with hot water, wash it out with water, add 70 mL of hydrochloric acid (4.5), and boil it at low temperature to dissolve the iron sheet. Transfer the solution into a 500mL conical flask, add 2g aluminum flakes (4.3), cover the flask tightly with a Geiger funnel with a rubber stopper, and add a saturated sodium bicarbonate solution (4.10) into the Geiger funnel. Shake frequently. When the reaction is intense, cool it with ice water or tap water to prevent the solution from rushing out of the bottle. When the reaction is slow, move the bottle to an electric furnace, boil it for 1 to 2 minutes after the aluminum flakes are dissolved, remove the running water and cool it to room temperature. During the cooling process, be sure to add a saturated sodium bicarbonate solution (4.10) at any time to isolate it from air. 6.3.5 Remove the Geiger funnel, inject the saturated sodium bicarbonate solution in the funnel into the conical flask, quickly add 5mL starch solution (4.12), and titrate with potassium iodate standard solution (4.11) until the solution turns light blue. 7 Calculation of analysis results
The percentage of tin is calculated according to formula (1):
Sn(%)=(VV.)×0. 0010x
Wherein; V. Volume of potassium iodate standard solution consumed by titration test solution, mL V.--Volume of potassium iodate standard solution consumed by titration blank test, mL; m Mass of sample, g
8 Allowable difference
0.10(V,-V.)
The mass of tin equivalent to 1.0CmL potassium iodate standard solution, g. The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 1. Table 1
3.00~-5.00
>5.00~8.00wwW.bzxz.Net
>8.00~10.00
Additional Notes:
This standard was proposed and managed by Guilin Electric Science Research Institute of the Ministry of Machinery Industry. This standard was drafted by Guangzhou Electric Alloy Factory, and Guilin Electric Science Research Institute participated in the drafting. The main drafters of this standard are Lai Bingxin and Liu Yaoping.
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