JB/T 7777.2-1995 Silver Oxide Tin Oxide Indium Oxide Electrical Contact Material Chemistry JB/T7777.2-1995 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, steel electric contact material EDTA volumetric method for determination
Subject content and scope of application
This standard specifies the determination method of indium content in silver oxide, tin oxide, indium electric contact material. JB/T7777.2—1995
This standard is applicable to the determination of steel content in silver oxide, tin oxide, electric contact material. Determination range: 1.00%~5.00%. 2 Reference standards
JB4107.1—85
3 Principle of method
General rules and general provisions for chemical analysis methods of electric contact materials The sample is decomposed with sulfur-nitric acid mixture, and silver and tin are masked with thiourea and tartaric acid. At pH 2.6, with xylenol orange as the indicator, the steel is titrated with EDTA standard solution.
4 ReagentsbzxZ.net
4.1 Mixed acid: 3 volumes of sulfuric acid (p1.84 g/mL) and 2 volumes of nitric acid (p1.42 g/mL). 4.2 Nitric acid (1+8).
4.3 Ammonium hydroxide (1+1), prepare when needed. 4.4 Thiourea solution (100 g/L).
4.5 Tartaric acid solution (400 g/L).
4.6 Disodium ethylenediaminetetraacetic acid (EDTA) standard titration solution [C(ClHN,O,Na，·2HO)=0.008 mol/L]4.6.1 Preparation
Weigh 3 g EDTA, dissolve in 1000 mL water, and mix well. 4.6.2 Calibration
Use 0.90g pure silver (99.95%), 0.05g tin dioxide (99.95%) and 0.0500g pure indium (99.99%) to synthesize the test material and proceed according to 5.2.
4.6.3 The number of grams of indium equivalent to each milliliter of EDTA standard titration solution is calculated according to formula (1): my
-the mass of indium in the synthetic test material, gt
where: m
V,-the volume of the synthetic test solution taken, mL
V.-the total volume of the synthetic test solution, mL,
V,-the volume of the EDTA standard titration solution consumed in the titration, mL. 4.7 Xylenol orange solution (1g/L).
4.8 Precision test paper (pH 2-3, interval 0.2 units). 5 Analysis steps
Approved by the Ministry of Machinery Industry on October 9, 1995
Implemented on January 1, 1996
5.1 Test material
Weigh about 1g of test material, accurate to 0.0001g. 5.2 Determination
JB/T7777.2-1995
5.2.1 Place the test material (5.1) in a 250mL beaker, add 20mL of mixed acid (4.1), cover with a watch glass, and heat to decompose the test material. When there are no small bubbles, shake twice, continue to heat until thick white smoke appears in the tube, remove and cool. Rinse the watch glass and the wall of the cup with water to make the test solution volume about 150mL, and cool. Transfer to a 250mL volumetric flask, dilute to the mark with water, and mix well. 5.2.2 Take 25.00mL of the test solution and transfer it to a 300mL conical flask, add 20mL of thiourea solution (4.4) and 10mL of tartaric acid solution (4.5), and adjust the pH of the test solution to 2.6 with ammonium hydroxide (4.3) and nitric acid (4.2) (check with precision test paper). Add 2-3 drops of xylenol orange solution (4.7) and titrate with EDTA standard titration solution (4.6) until the solution changes from purple-red to bright yellow. Note: If the room temperature is below 15℃, first heat the test solution to 60-70℃, and then adjust the pH of the test solution to 2.6 with ammonium hydroxide (4.3). 6 Calculation of analysis results
The percentage of indium is calculated according to formula (2):
CV. .V.
In(%)=
Where: C—-the mass of indium per milliliter of EDTA standard titration solution, g; V. -Total volume of test solution, mL;
V,—Volume of EDTA standard titration solution consumed in titrating test solution, mL; V,—Volume of test solution taken, mL;
mMass of test material, 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
1.00~5.00
Additional notes:
This standard was proposed and coordinated by the Guilin Electrical Science Research Institute of the Ministry of Machinery Industry. This standard was drafted by Guangzhou Electrical Alloy Factory, and Guilin Electrical Science Research Institute participated in the drafting. The main drafters of this standard are Lai Bingxin and Jian Lanxiang Allowable difference
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