This standard specifies the determination method of zinc content in silver zinc oxide electrical contact materials. This standard is applicable to the determination of zinc content in silver zinc oxide electrical contact materials, and the determination range is 4.00% to 12.00%. JB/T 7774.1-1995 Chemical analysis method for silver zinc oxide electrical contact materials JB/T7774.1-1995 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Chemical analysis method of silver zinc oxide electric contact material EDTA volumetric method for determination of zinc content
1 Subject content and scope of application
This standard specifies the determination method of zinc content in silver zinc oxide electric contact material. JB/T 7774.11995
This standard is applicable to the determination of zinc content in silver zinc oxide electric contact material. The determination range is 4.00% to 12.00%. 2 Reference standards
General principles and general provisions for chemical analysis methods of electric contact materials JB4107.1-85
3 Principle of the method
The sample is decomposed with nitric acid, silver, nickel, aluminum, cadmium and bismuth ions are respectively masked with sulfur, diacetyl, ammonium fluoride and potassium iodide, the acidity is adjusted with hexamethylenetetramine, bromocresol green is added as a coloring agent, xylenol orange is used as an indicator, and EDTA standard solution is titrated. 4 Reagents
Nitric acid (1+1).
Sulfur gland solution (100g/) Prepared on the same day.
Ammonium fluoride solution (50g/l).
Butanedione ethanol solution (5g/).
Potassium iodide solution (600g/l).
4.6 Hexamethylenetetramine solution (100g/1). Zinc standard solution (0.01mol/): Weigh 0.6538g pure zinc (99.95%) into a 250ml beaker, dissolve in 10ml nitric acid (4.1), 4.7
Transfer into a 1000ml volumetric flask. Dilute to the mark. 4.8 Standard titration solution of disodium ethylenediaminetetraacetate [C(CHN,O.Na:·2H,O)=0.01mol/L]] 4.8.1 Preparation: Weigh 3.72g disodium ethylenediaminetetraacetate, dissolve it in water, transfer it into a 1000ml volumetric flask, and dilute to the mark. Shake well. Calibration: Take three portions of 10.00ml zinc standard solution (4.7). Place them in 250ml conical flasks respectively and proceed according to 5.2.2. 4.8.2
The actual concentration of the standard titration solution of disodium ethylenediaminetetraacetate is calculated according to formula (1): C, V
Where:
-concentration of zinc standard solution, mol/l;
V, volume of zinc standard solution, ml;
V. —volume of the standard titration solution of disodium ethylenediaminetetraacetate, ml. (1)
Take the average of the three calibration results. The extreme difference of the milliliters of EDTA standard titration solution consumed in the three calibrations shall not exceed 0.10 ml. 4.9 Bromocresol green solution (1 g/L). Dissolve 0.1 g of the reagent in 20 ml of ethanol and dilute to 100 ml. Xylenol orange solution (2 g/L). Use within one week after preparation. 4.10
Approved by the Ministry of Machinery Industry on October 9, 1995
Implemented on January 1, 1996
5 Analysis steps
5.1 Test material
Weigh 1 g of the sample accurately to 0.0001 g.
5.2 Determination
JB/T7774.1-1995
5.2.1 Place the sample (5.1) in a 250ml beaker, add 10ml nitric acid (4.1), heat at low temperature to dissolve, remove nitrogen oxides, remove and cool to room temperature. Rinse the beaker wall with water, transfer to a 100ml volumetric flask, and dilute to the scale. Shake well. 5.2.2 Accurately transfer 10.00ml of the solution (5.2.1) into a 250ml conical flask, add 40ml thiourea solution (4.2), 5ml amine fluoride solution (4.3), and 5ml diacetyl solution (4.4). 20ml potassium iodide solution (4.5), 8 drops of bromocresol green solution (4.9), 10ml hexamethylenetetramine solution (4.6), 5 drops of xylenol orange solution (4.10), then titrate with EDTA standard titration solution (4.8) from purple-red to yellow-green as the end point. wwW.bzxz.Net
Calculation of analysis results
The percentage of zinc is calculated according to formula (2):
CyV,x0.06538
Zn(%)=
V——Volume of disodium ethylenediaminetetraacetic acid standard titration solution (4.8) consumed in titration, ml; where:
C. —Actual concentration of disodium ethylenediaminetetraacetic acid standard titration solution, mol/l; 0.06538The mass of zinc equivalent to 1.00ml disodium ethylenediaminetetraacetic acid standard titration solution, g; V, dilution volume of sample solution, ml;
V. - volume of sample solution, ml;
m-mass of sample, g.
7 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 1. Table 1
4.00~8.00
>8.00~12.00
Additional instructions:
This standard was proposed and managed by the Guilin Electric Science Research Institute of the Ministry of Machinery Industry. This standard was drafted and drafted by Shanghai Alloy Material General Factory. The main drafters of this standard were Li Yongkang, Ling Xiangqun, Hu Xinxu2
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