This standard specifies the determination method of nickel content in silver tungsten carbide electrical contact materials. This standard is applicable to the determination of nickel content in silver tungsten carbide electrical contact materials. Determination range: 0.50% to 2.00%. JB/T 7778.2-1995 Chemical analysis method for silver tungsten carbide electrical contact materials JB/T7778.2-1995 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Chemical analysis method for silver tungsten carbide electric contact material - Determination of nickel content by diacetyl spectrophotometry
1 Subject content and scope of application
This standard specifies the method for determining the nickel content in silver tungsten carbide electric contact material. JB/T 7778. 2--1995
This standard is applicable to the determination of nickel content in silver tungsten carbide electric contact material. Determination range: 0.50% to 2.00%. 2 Reference standards
GB 7729--87
General rules for spectrophotometric methods for chemical analysis of metallurgical products JB4107.1-85
General rules and general provisions for chemical analysis methods of electrical contact materials 3 Principle of the method
The sample is decomposed with sulfuric acid and ammonium sulfate at high temperature, silver is separated with sodium chloride, and interfering elements are masked with potassium sodium tartrate. In an alkaline medium and in the presence of an oxidant, diacetyl and nickel (1) form a red complex, and the absorbance is measured at a wavelength of 470nm on a spectrophotometer. 4 Reagents
4. 1 Sulfuric acid (p 1.84 g/mL).
4.2 Ammonium sulfate (solid).
4.3 Potassium sodium tartrate solution (50g/L). 4.4 Sodium hydroxide solution (300g/L). Store in a plastic bottle 4.5 Sodium hydroxide solution (50g/L). Store in a plastic bottle 4.6 Sodium chloride solution (30 g/L).
4.7 Ammonium persulfate solution (50 g/L). Prepare 4.8 Butanedione solution (10 g/L) on the same day: weigh 10 g butanedione into a plastic cup, add 1000 mL sodium hydroxide solution (4.5), stir to dissolve, and store in a plastic bottle.
4.9 Nickel standard stock solution: weigh 1.0000 g pure nickel (99.95%) into a 250 mL beaker, add 10 mL nitric acid (1 + 1), heat to dissolve and drive out nitrogen oxides, cool to room temperature, transfer to a 1000 mL volumetric flask, dilute to scale with water, and mix. This solution contains 1 mg nickel in 1 mL.
4.10 Nickel standard solution: transfer 10.00 mL. Nickel standard stock solution (4.9) into a 200 mL volumetric flask, dilute to scale with water, and mix. This solution contains 50μg nickel in 1mL.
s Instrument
Spectrophotometer.
6 Analysis steps
6.1 Sample
Approved by the Ministry of Machinery Industry on October 9, 1995
Implemented on January 1, 1996
Weigh 0.2g of sample, accurate to 0.0001g. 6.2 Blank test
Carry out a blank test with the sample.
6.3 Determination
JB/T 7778.2—1995
6.3.1 Place the sample (6.1) in a 250mL conical flask, add 3mL sulfuric acid (4.1) and 1-2g ammonium sulfate (4.2), and heat to decompose the sample. 6.3.2 When cooled to 50-80℃, add 10mL of water, drop sodium hydroxide solution (4.4) to dissolve the white precipitate, add 10mL of potassium sodium tartrate solution (4.3), 10mL of sodium chloride solution (4.6), heat and boil until the solution is clear, and cool to room temperature. 6.3.3 Filter into a 100mL volumetric flask with slow qualitative filter paper, wash the conical flask and filter paper with a small amount of water for more than three times, dilute with water to the scale, and mix.
6.3.4 Transfer 5.00mL of test solution (6.3.3) into a 50mL volumetric flask, add 5mL of potassium sodium tartrate solution (4.3), 5mL of sodium hydroxide solution (4.5), 5mL of ammonium persulfate solution (4.7) and 5mL of diacetyl solution (4.8), dilute with water to the scale, and mix. Let stand for 10 min.
6.3.5 Transfer part of the solution into a 0.5 cm cuvette and measure its absorbance at a wavelength of 470 nm on a spectrophotometer with water as a reference. 6.3.6 Subtract the blank test absorbance and find the corresponding nickel content from the working curve. 6.4 Drawing of the working curve
6.4.1 Transfer 0, 1.00, 2.00, 3.00, 4.00, and 5.00 mL of the nickel standard solution (4.10) and place them in 50 mL volumetric flasks respectively. The following is carried out according to 6.3.4 to 6.3.5. www.bzxz.net
6.4.2 Subtract the reagent blank absorbance and draw the working curve with the nickel content as the horizontal axis and the absorbance as the vertical axis. 7 Calculation of analytical results
The percentage of nickel is calculated according to formula (1):
Where: mi
Ni(%)m :V. X10--
m. ·Vi
Nickel amount found on the working curve, g,
V. Total volume of test solution, mL
Vi--Volume of test solution taken, mL;
8Allowance difference
-Mass of the test material, &.
The difference in analysis results between laboratories should not be greater than the allowance difference listed in Table 1. Table 1
>1. 00~2. 00
Additional remarks:
This standard was proposed and managed by the Guilin Electric Science Research Institute of the Ministry of Machinery Industry. X 100 ***
Allowance difference
This standard was drafted by Tianshui Changcheng Electrical Alloy Material Factory, and Guilin Electric Science Research Institute participated in the drafting. The main drafters of this standard are Li Yuren Zhao Guangying Li Peitian%
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