This standard specifies the use of EDTA volumetric method to measure copper content. JB/T 7520.1-1994 Chemical analysis method for phosphorus copper solder EDTA volumetric method to determine copper content JB/T7520.1-1994 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Chemical Analysis Method of Phosphor Copper Brazing Filler
Determination of Copper Content by EDTA Volumetric Method
1 Subject Content and Scope of Application
This standard specifies the determination of copper content by EDTA volumetric method. This standard is applicable to the determination of copper content in phosphor copper brazing filler, with a determination range of 80.00% to 95.00%. 2 Method Summary
JB/T 7520.1—94
After the sample is dissolved in hydrochloric acid and hydrogen peroxide, an excess of EDTA solution is added to a slightly acidic solution with a pH of 5 to 6 to allow all the complexing elements to be complexed, and then a combined masking agent composed of thiourea, 1,10-phenanthroline and ascorbic acid is added to selectively decompose the Cu-EDTA complex, and finally the released EDTA is titrated with a lead standard solution. 3 ReagentsbZxz.net
3.1 Hydrochloric acid (p1.19 g/mL).
3.2 Hydrogen peroxide (commercially available at 30%).
3.3 Hexamethylenetetramine solution (30%). 3.4 Sulfur gland solution (10%).
3.5 Ascorbic acid solution (5%), prepare when needed. 3.61.10-Phenanthroline solution (0.1%).
3.7 Xylenol orange indicator (0.5%).
3.8 EDTA standard solution (0.05 mol/L)
3.9 Copper standard solution: Weigh 1.0000g of metallic copper (purity above 99.99%) and place it in a 250ml conical flask, add 20mL of hydrochloric acid (3.1), and add 15mL of hydrogen peroxide (3.2) in batches to dissolve the sample. After it is completely dissolved, boil for about 1min, cool, weigh it in a 200ml volumetric flask, dilute it to the mark with water, and mix well. 1mL of this solution contains 5.00mg of copper. 3.10 Lead standard solution (0.01000mol/L): Weigh 2.0720g of metallic lead (purity above 99.99%), place in a 150mL tall beaker, add 15mL nitric acid (1+2), cover with blood, heat to dissolve, boil to remove nitrogen oxides, cool, transfer to a 1000mL volumetric flask, dilute to scale with water, and mix. It can also be prepared with lead nitrate (superior grade). 3.10.1 Calibration
Accurately pipette 10mL of copper standard solution (3.9) into a 300mL conical flask, and calibrate according to 4.2.2 and 4.2.3. 3.10.2 Calculate the titer of the lead standard solution against copper according to formula (1): T = 0. 05
(1)
Wherein: T-
The titer of the lead standard solution against copper, g/mL; The volume of the lead standard solution consumed during titration, mL. Take three portions of the copper standard solution for calibration and take the average value of the titer. The allowable extreme value should be less than 0.01 mg/mL. If it exceeds this value, recalibrate.
Approved by the Ministry of Machinery Industry of the People's Republic of China on December 9, 1994 316
Implemented on October 1, 1995
4 Analysis steps
4.1 Sample volume
Weigh 1.0000g of sample.
4.2 Determination
JB/T 7520. 1-94
4.2.1 Place the sample (4.1) in a 250mL conical flask, add 20mL hydrochloric acid (3.1), add 15mL hydrogen peroxide (3.2) in portions to dissolve the sample, boil for about 1min after complete dissolution to decompose the excess hydrogen peroxide, cool, transfer to a 200mL volumetric flask, dilute to scale with water, and mix.
4.2.2 Accurately pipette 10mL of the solution into a 300mL conical flask, add 20mL of DTA standard solution (3.8), rinse the flask wall with water, mix, heat and boil for about 1min, cool, add 15mL of hexamethylenetetramine solution (3.3) and 3~4 drops of xylenol orange indicator (3.?), and titrate with lead standard solution (3.10) until the solution changes from yellow-green to blue-purple. Ignore the number of mL consumed. 4.2.3 Add 30 mL of thiophene solution (Article 3.4), 10 mL of ascorbic acid solution (Article 3.5) and 10 drops of 1,10-phenanthroline solution (Article 3.6), and stir until the solution turns yellow (about 3 minutes). Titrate with lead standard solution (Article 3.10) until the solution turns from yellow to red. 5 Calculation of analysis results
Calculate the percentage of copper according to formula (2):
Cu(%)=
Where: Vi is the volume of lead standard solution consumed during titration, mLT is the titer of lead standard solution to copper, g/mLV.
Total volume of sample solution, mL;
6 Allowable difference
Volume of sample solution, mL;
Weigh the sample.
The difference in analysis results should not be greater than the allowable difference listed in Table 1. V, TV.
80.00 ~95. 00
Additional Notes:
This standard was proposed by Harbin Welding Research Institute of the Ministry of Machinery Industry. This standard was drafted by Harbin Welding Research Institute. The main drafters of this standard are Bai Shudu, Lin Kegong and Sun Xiaohong. X100
Allowance
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