This standard specifies the determination method of aluminum content in silver cadmium oxide electrical contact materials. This standard is applicable to the determination method of aluminum content in silver cadmium oxide electrical contact materials. Determination range: 0.05% to 0.10%. JB/T 7776.8-1995 Chemical analysis method for silver cadmium oxide electrical contact materials JB/T7776.8-1995 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Chemical analysis method of silver oxide pick electric contact material Chrome azure S spectrophotometric method for aluminum content
1 Subject content and scope of application
This standard specifies the determination method of aluminum content in silver oxide cadmium electric contact material. JB/T 7776.8--1995
This standard is applicable to the determination of aluminum content in silver oxide pick electric contact material. Determination range: 0.05%~0.10%. 2 Reference standards
GB772887
JB 4107.1-85
3 Principle of method
General rules for spectrophotometric method for chemical analysis of metallurgical products General rules and general provisions for chemical analysis methods of electric contact materials The sample is decomposed with nitric acid, and the residue after filtration is dissolved with potassium pyrosulfate. The acidity is controlled with ammonium acetate buffer solution to form a colored complex with aluminum[］ and chrome azure S. Measure the absorbance at a wavelength of 610 nm on a spectrophotometer. 4 Reagents
Potassium pyrophosphate (solid).
Nitric acid (1+1).
Paper pulp (prepared by boiling quantitative filter paper). bzxz.net
Thiourea solution (50 g/L).
Ascorbic acid solution (10 g/L).
Gum Arabic solution (5 g/L).
Chrome azure S solution (2 g/L). Dissolve in water and filter out any insoluble matter before use. 4.7
Ammonium acetate buffer solution (200 g/L).
Aluminum standard stock solution: Weigh 0.8792g of aluminum potassium sulfate [Al,(SO,),·K,SO,·24H,O], place in a 200mL beaker, dissolve in 4.9
water, transfer to a 1000mL volumetric flask, dilute to scale, and mix. This solution contains 0.05mg aluminum in 1mL. 4.10 Aluminum standard solution: Transfer 10.00mL of aluminum standard stock solution (4.9) to a 100mL volumetric flask, dilute to scale, and mix. This solution contains 5μg aluminum in 1mL.
4.11 Silver solution: Weigh 2.50g of pure silver (99.95%) and place in a 250mL beaker, add 10mL of nitric acid (4.2), cover with a beaker, heat to dissolve, continue heating and evaporation until about 2-3mL is left, remove, and cool to room temperature. Transfer to a 250m volumetric flask, dilute to scale, and mix. 1 mL of this solution contains 10 mg of silver.
4.12 Radium solution: Weigh 0.50 g of pure saw (99.95%) and place it in a 250 mL beaker, add 5 mL of nitric acid (4.2), cover with a watch glass, heat to dissolve, continue heating and evaporating until about 2 to 3 ml is left, remove it and cool to room temperature. Transfer it to a 250 mL volumetric flask, dilute to the scale, and mix well. 1 mL of this solution contains 2 mg of cadmium.
5 Instruments
Approved by the Ministry of Machinery Industry on 199510-09
Implemented on 1996-01-01
Spectrophotometer.
6 Analysis steps
6.1 Test materials
Weigh 0.5 g of test materials to an accuracy of 0.0001 g. 6.2 Blank test
JB/T 7776.8—1995
Pipette 2.0mL of silver solution (4.11) and 1.0mL of thiocyanate solution (4.12) into a 100mL volumetric flask. The following operations are carried out according to 6.3.5.
6.3 Determination
6.3.1 Place the sample (6.1) in a 250mL beaker, add 10mL of nitric acid (4.2), cover with a watch glass, heat to dissolve, evaporate until a film appears on the surface of the solution, remove, and cool to room temperature. Dissolve the salts in 25mL of water, add about one ox-horn spoon of pulp (4.3), heat to boil, filter with quantitative filter paper into a 200mL volumetric flask, and wash the filter paper and beaker 3 times each (the filtrate is retained). 6.3.2 Transfer the filter paper and precipitate into a platinum crucible, heat until the filter paper is dry, transfer into a muffle furnace, burn at 700-800℃ until the filter paper is ash, take out and cool.
6.3.3 Add 2g potassium pyrosulfate (4.1) to platinum, transfer into a muffle furnace, melt at 650-700℃ for 30min, take out and cool. 6.3.4 Soak the melt in the platinum crucible with warm water, combine it with the filtrate (6.3.1), dilute to scale, and mix. 6.3.5 Take 10.00mL of the sample solution, add 5.0mL of thiourea solution (4.4), 2mL of ascorbic acid solution (4.5), 2mL of gum arabic solution (4.6), 2.0mL of chrome azure S solution (4.7) into a 100mL volumetric flask, add 8mL of ammonium acetate buffer solution (4.8), dilute to scale, and mix. Leave for 25 minutes.
6.3.6 Transfer part of the solution into a 1 cm cuvette, use the blank test as a reference, measure the absorbance at a wavelength of 610 nm on a spectrophotometer, and find the corresponding amount of aluminum from the working curve. 6.4 Drawing of the working curve
6.4.1 Transfer 0, 1.00, 2.00, 3.00, 4.00, 5.00 mL of aluminum standard solution (4.10) to a set of 100 mL volumetric flasks, add 2.0 mL of silver solution (4.11) and 1.0 mL of cadmium solution (4.12). The following operations are carried out according to 6.3.5 and 6.3.6. Use the zero concentration solution as a reference and measure the absorbance.
6.4.2 Draw a working curve with the amount of aluminum as the horizontal axis and the absorbance as the vertical axis. 7 Calculation of analysis results
The percentage of aluminum is calculated according to formula (1):
Al(%)=m : V. X10-c
Wherein: m. The amount of aluminum found from the working curve, μg; V. The total volume of the sample solution, mL;
V, the volume of the sample solution taken, mL;
mi—the 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
0.05~0.07
>0.07~0.10
Allowable difference
Additional instructions:
JB/T7776.8—1995
This standard is proposed and managed by the Guilin Electric 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 Tianjin Electrical Alloy Factory. The main drafters of this standard are Yi
Zhao Shiyu Gao Sixin
Li Yuren
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