This standard specifies the determination of phosphorus content by barium molybdate photometry. This standard is applicable to the determination of phosphorus content in phosphorus copper brazing materials, with a determination range of 4.00% to 8.00%. JB/T 7520.3-1994 Chemical analysis method for phosphorus copper brazing materials Determination of phosphorus content by vanadium molybdate photometry JB/T7520.3-1994 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Chemical Analysis Method of Phosphorus Copper Brazing Material
Determination of Phosphorus by Vanadium-Molybdenum Acid Photometric Method
Subject Content and Applicable Scope
This standard specifies the determination of phosphorus by vanadium-aluminum acid photometric method. This standard is applicable to the determination of phosphorus in phosphorus copper brazing material, with a determination range of 4.00% to 8.00%. 2 Method Summary
JB/T7520.3-94
After the sample is dissolved in acid, potassium permanganate is added to oxidize phosphorus to orthophosphoric acid, excess potassium permanganate is decomposed with hydrogen peroxide, ammonium vanadate is added, boiled to decompose hydrogen peroxide, and ammonium molybdate is added to form yellow phosphorus-vanadium-molybdenum heteropoly acid, which is then used for photometric determination. 3 Reagents
3.1 Nitric acid (2+3).
3.2 Nitric acid (1+5).
Mixed acid: Add 25mL hydrofluoric acid (commercially available 40%) to 1000mL nitric acid (2+1), and store in a plastic bottle. 3.3
Acid solution (4%).
3.5 Potassium permanganate solution (1%).
3.6 Peroxide (1+9).
3.7 Ammonium vanadate solution (0.25%): Weigh 2.5g ammonium vanadate and dissolve it in 500mL hot water, cool, slowly add 20mL nitric acid (1+1) under constant stirring, and dilute to 1000mL with water. 3.8 Ammonium molybdate solution (10%): Weigh 100g ammonium sawate and dissolve it in 800mL water at 50°C, cool, dilute to 1000mL with water, and mix. Filter with dense filter paper and store in a plastic bottle. 3.9 Phosphorus standard solution: Weigh 0.8788g potassium dihydrogen phosphate (standard reagent) placed in a desiccator overnight and dissolve it in 200mL water, add 10ml nitric acid (3.2), transfer to a 1000ml volumetric flask, dilute to scale with water, and mix well. This solution contains 0.20mg phosphorus in 1mL. 3.10 Metallic copper (purity above 99.99%). 4www.bzxz.net
Analysis steps
4.1 Sample amount
Weigh 0.5000g sample.
4.2 Blank test
Weigh the same amount of metallic copper (3.10) as the sample as the sample as a blank. 4.3 Determination
4.3.1 Dissolution of sample
4.3.1.1 Tin-free sample
Place the sample (4.1) in a 125mL conical flask, add 25mL nitric acid (3.1), heat to dissolve, boil for 2-3min, cool, transfer to a 200mL volumetric flask, dilute to the mark with water, and mix. Approved by the Ministry of Machinery Industry of the People's Republic of China on December 9, 1994 320
Implemented on October 1, 1995
4.3.1.2 Tin-containing sample
JB/T 7520.3-94
Put the sample (4.1) in a 100ml ethylene cup, add 10ml of mixed acid (3.3), dissolve at room temperature, cool, add 10ml of boric acid solution (3.4), let stand for 5min, transfer to a 200ml volumetric flask, dilute to scale with water, and mix well. Do not leave it for a long time. 4.3.2 Accurately draw 10mL of solution (4.3.1.1 or 4.3.1.2) in two portions, measure into 100mL dual-purpose bottles, add 20mL nitric acid (3.2), heat and boil for 1min, add 2mL potassium permanganate solution (3.5), continue to boil for 3040s, remove, add 1mL hydrogen peroxide (3.6), mix, add 10mL ammonium vanadate solution (3.7) after the solution is clear, heat and boil until the solution changes from brown to transparent blue (about 1.5-2min, indicating that hydrogen peroxide is completely decomposed), and cool. 4.3.3 Add water to a volume of about 80mL, add 10mL ammonium vanadate solution (3.8) to one portion of the solution, dilute to the mark with water, mix, and leave for 20min. This solution is the color developing solution. Dilute the other portion of the solution with water to the mark, mix, and this solution is the sample blank solution. 4.3.4 Pipette a portion of the colorimetric solution into a 1cm colorimetric III, use the sample blank solution as the reference solution, and measure its absorbance at a wavelength of 410~~420nm on a spectrophotometer. The measured absorbance is the absorbance of the alkali-removed reagent blank (Article 4.2), and the corresponding phosphorus content is found from the working curve. 4.4 Drawing of the working curve
Accurately pipette 0, 2.50, 5.00, 7.50, 10.00ml of phosphorus standard solution (Article 3.9) into a 100ml dual-purpose bottle, add water to 10ml, and follow the procedures of Articles 4.3.2~~4.3.4. Use 0ml as the reference solution and measure its absorbance. Draw the working curve with phosphorus content as the horizontal axis and absorbance as the vertical axis.
5 Calculation of analysis results
Calculate the percentage of phosphorus according to the following formula:
P(%)-mV.×10°
Wherein: m-—Phosphorus content found from the working curve, mgsV. ——Total volume of the sample solution, mL
V,—Volume of the sample solution taken, mL;
6 The allowable total
sample weight is g.
The difference in the analysis results should not be greater than the allowable tolerance listed in Table 1. Table 1
4.00~8.00
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 Shuyun, Lin Kegong and Sun Xiaohong. X100
Allowable tolerance
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