This standard specifies the determination method of bismuth in silver cadmium oxide electrical contact materials. This standard is applicable to the determination method of bismuth in silver cadmium oxide electrical contact materials. Determination range: 0.05% to 0.50%. JB/T 7776.6-1995 Chemical analysis method for silver cadmium oxide electrical contact materials JB/T7776.6-1995 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Chemical analysis method for silver oxide pick electric contact material Thiourea spectrophotometric method for determination of bismuth content
1 Subject content and scope of application
This standard specifies the determination method for bismuth content in silver oxide pick electric contact material. JB/T7776.6—1995
This standard is applicable to the determination of bismuth content in silver oxide pick electric contact material. Determination range: 0.05%~0.50%. 2 Reference standards
GB7729--87
General rules for spectrophotometric methods for chemical analysis of metallurgical products JB 4107.1--85
5 General rules and general provisions for chemical analysis methods of electrical contact materials 3 Principle of the method
The sample is decomposed with nitric acid and tartaric acid, and silver is separated with sodium chloride. In the acidic medium, bismuth [■] forms a yellow soluble complex with sulfur vein, and the absorbance is measured at a wavelength of 445nm on a spectrophotometer. 4 Reagents
4.1 Nitric acid (1+2).
4.2 Nitric acid (1+14).
4.3 Tartaric acid solution (50g/L).
4.4 Sodium chloride solution (50g/L).
4.5 Thiourea solution (100g/L). (Prepare on the same day and filter before use). 4.6 Bismuth standard solution: Weigh 0.2310 g of bismuth nitrate [Bi(NO,)a·5H,O] in a 1000 mL volumetric flask, dissolve and dilute to scale with nitric acid (4.2), and shake well. This solution contains 0.10 mg bismuth in 1 mL. 5 Instruments
Spectrophotometer.
6 Analysis stepswww.bzxz.net
6.1 Sample
Weigh 0.2 g of sample, accurate to 0.0001 g. 6.2 Blank test
Perform a blank test with the sample.
6.3 Determination
6.3.1 Place the sample (6.1) in a 250 mL conical flask, add 10 mL of tartaric acid solution (4.3) and 5 mL of nitric acid (4.1), heat at low temperature to dissolve, remove all nitrogen oxides, and cool to room temperature. Wash the bottle wall with a small amount of water. 6.3.2 Add 16.0 mL of sodium chloride solution (4.4), heat and boil for 5 minutes to make the silver chloride precipitate condense, remove and cool, add 10 mL of nitric acid (4.1).
JB/T7776.61995
6.3.3 Filter into a 100 mL volumetric flask with slow quantitative filter paper, wash the conical flask and the precipitate with 20~25 mL of nitric acid (4.2) for more than 3 times.
6.3.4 Add 30 mL of sulfur gland solution (4.5), dilute to the scale with nitric acid (4.2), and mix well. Let stand for 15 minutes. 6.3.5 Transfer part of the solution into a 3 cm colorimetric blood, use water as a reference, and measure the absorbance at a wavelength of 445 nm on a spectrophotometer. 6.3.6 Subtract the absorbance of the blank test and find the corresponding bismuth content from the working curve. 6.4 Drawing of the working curve
6.4.1 Transfer 0, 2.00, 4.00, 6.00, 8.00, 10.00mL of bismuth standard solution (4.6) to a set of 100mL volumetric flasks, add 20mL nitric acid (4.1), 16.0mL sodium chloride solution (4.4), 30mL sulfur gland solution (4.5), dilute to the scale, mix well, and let stand for 15min. The following operations are carried out according to 6.3.5. 6.4.2 Subtract the absorbance of the zero concentration solution, use the bismuth content as the horizontal axis and the absorbance as the vertical axis to draw the working curve. 7 Calculation of the analysis results
The percentage of bismuth is calculated according to formula (1):
Bi(%)=m×10-
Where: m. —Amount of bismuth obtained from the working curve, ug; mass of the sample, g;
8 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 1. Table 1
0.05~0.15
>0.15~0.30
>0.30~0.50
Additional notes:
This standard was proposed and managed by the Guilin Electrical Science Research Institute of the Ministry of Machinery Industry. This standard was drafted by the State-owned No. 615 Factory. This standard was drafted by the Tianshui Great Wall Electrical Alloy Material Factory. The main drafters of this standard were Zhao Guangying, Li Yuren, and Zhao Shiyu. Allowable difference
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