This standard specifies the determination of tin content by hypophosphite reduction volumetric method. JB/T 7520.5-1994 Chemical analysis method for phosphorus copper solder Determination of tin content by hypophosphite reduction volumetric method JB/T7520.5-1994 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Chemical Analysis Method of Phosphor Copper Nail Material
Determination of Tin by Hypophosphite Reduction Volumetric Method! bZxz.net
Subject Content and Scope of Application
This standard specifies the determination of tin content by hypophosphite reduction volumetric method. This standard is applicable to the determination of tin content in phosphor steel solder. The determination range is 7.00%~~11.00%. 2 Method Extraction
JB/T 7520.5-94
The sample is dissolved in hydrochloric acid and hydrogen peroxide, and high mercuric fluoride is used as a catalyst. Sodium hypophosphite is added under air-tight conditions to reduce Sn[V gate to SnL I], and titrated with potassium iodate standard solution. 3 Reagents
3.1 Hydrochloric acid (1+1).
3.2 Hydrogen peroxide (commercially available 30%).
3.3 Mercuric chloride solution: weigh 1g mercuric chloride, dissolve in 600mL water, add 700mL hydrochloric acid (pl.19g/mL), mix. 3.4 Sodium hypophosphite (NaH2PO2·HO) solution (50%). 3.5 Saturated sodium bicarbonate solution.
3.6 Ammonium thiocyanate solution (25%).
3.7 Potassium iodide solution (10%).
3.8 Starch solution (1%), prepare when needed. 3.9 Standard solution: weigh 0.2000g metallic tin (purity of 99.9% or more) in a 100mL beaker, add 20mL hydrochloric acid (pl.19g/mL), do not heat, after complete dissolution, transfer to a 100ml volumetric flask, dilute to scale with water, and mix. This solution contains 2.00mg of tin in 1mL.
3.10 Potassium iodate solution: Weigh 1.18 g potassium iodate and 0.5 g sodium hydroxide and dissolve them in 200 mL water, then add 8 g potassium iodide, transfer to a 1000 mL volumetric flask, dilute to the mark with water, and mix. 3.10.1 Calibration
Weigh 0.4 g metal steel (99.9% or more) and place it in a 500 mL conical flask, add 10 mL hydrochloric acid (3.1) and 5 mL hydrogen peroxide (3.2), heat slightly to dissolve completely, boil to remove excess hydrogen peroxide, add 25.00 mL standard solution (3.9), and proceed as per 4.2.2 and 4.2.3.
3.10.2 Calculate the titer of the potassium iodate standard solution pair according to formula (1): T=0. 050
Wherein: T—titer of the potassium iodate standard solution pair, /mL—volume of the potassium iodate standard solution consumed during titration, ml. V.
Take three portions of the tin 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 324
Implemented on October 1, 1995
4 Instruments
Cadmium reduction device (as shown in Figure 1).
5 Analysis steps
5.1 Sample quantity
Weigh 0.5000g of sample.
5.2 Determination
JB/T7520.5—94
Figure 1 Tin reduction device
5.2. Place the sample (5.1) in a 500mL conical flask, add 10mL hydrochloric acid (3.1) and 5mL hydrogen peroxide (3.2), heat and dissolve completely, and boil until no small bubbles appear. 5.2.2 Add 65mL high mercuric chloride solution (3.3) and 10mL sodium hypophosphite solution (3.4), put the upper pot reduction device, and inject saturated sodium bicarbonate solution (3.5) into it, heat to boiling, and keep it slightly boiling for 5 minutes before removing it, add saturated sodium bicarbonate solution (3.5) to the tin reducer, wait for the solution to cool slightly, and then place it in ice water to cool to below 10℃. 5.2.3 Remove the reducer, quickly add 10mL of ammonium thiocyanate solution (Article 3.6), 5mL of potassium iodide solution (Article 3.7) and 10mL of starch solution (Article 3.8), and immediately titrate with potassium iodate standard solution (Article 3.10) until the solution turns blue and remains blue for 10 seconds, which is the end point. 6 Calculation of analysis results
Calculate the percentage of cadmium according to formula (2):
Sn(%):
Where: V—volume of potassium iodate standard solution consumed during titration, mLTi
Titre of potassium iodate standard solution on tin, g/nmL; sample weight.
7 Allowable difference
The difference in the analysis results should not be greater than the allowable difference listed in Table 1. X100
Allowance
Additional Notes:
JB/T 7520. 5--94
5. 00-~ 9.00
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. 326
9.00~~15.00
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