This standard specifies the determination method of indium content in gold alloys. This standard is applicable to the determination of indium content in AuNiIn9-8 alloy. Determination range: 7% to 10%. GB/T 15072.9-1994 Chemical analysis methods for precious metals and their alloys Determination of indium content in gold alloys GB/T15072.9-1994 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis methods for precious metals and their alloys
Determination of indium content in gold alloys
Gold alloys-Determination of indium contentSubject content and scope of application
This standard specifies the method for determining the indium content in gold alloys. This standard is applicable to the determination of indium content in AuNiIn9-8 alloy. Determination range: 7% to 10%. 2 Reference standards
GB1.4 Guidelines for standardization work Provisions for the preparation of chemical analysis methods GB1467 General principles and general provisions for chemical analysis methods for metallurgical products 3 Method summary
GB/T 15072.9---94
The sample is dissolved in mixed acid, gold is separated by sulfurous acid reduction, nickel is separated by dimethylethylenediamine precipitation, excess Na.EIDTA is added, and the amount is determined by back titration with standard lead nitrate titration solution using xylenol orange as an indicator. 4 Reagents
4.1 Sulfurous acid (pl.03g/ml).
4.2 Ammonia water (00. 90 g/mL).
4.3 Mixed acid: 1 unit volume of nitric acid (pl.42g/ml.) and 3 unit volumes of hydrochloric acid (p1.19g/ml). Prepare 4.4 Hydrochloric acid (1+1) when using.
4.5 Ammonia water (1-+1).
4.6 Ammonia water (1+99).
4.7 Sodium chloride solution (100g/1).
4.8 Tartaric acid solution (500g/L). Www.bzxZ.net
4.9 Ammonium chloride solution (250g/L).
4.10 Disodium ethylenediaminetetraacetic acid (NazEDTA·2Hz0) solution (0.01 mol/L). Dimethylethylenediethanol solution (15g/L). 4.11
4.12 Acetic acid-sodium acetate buffer solution (pH 5.8): Weigh 100g of crystalline sodium acetate (CH.COONa·8HO), add 4.5ml of glacial acetic acid (pl.05g/mL), and dilute to 500mL with water. 4.13 Standard steel solution: Weigh 0.1000g of metallic indium and place it in a 250ml beaker, add 20ml of hydrochloric acid (4.4), heat at low temperature to dissolve. Cool, transfer to a 100ml volumetric flask, dilute to scale with water, and mix well. This solution contains 1mg of indium in 1mL. 4.14 Standard lead nitrate titration solution c[Pb(NO,), J=0.01mol/1) 4.14.1 Preparation: Weigh 3.312g of lead nitrate, dissolve in water, and dilute to 1L. 4.14.2 Calibration: Calibration is carried out in parallel with the determination of the sample. Approved by the State Administration of Technical Supervision on May 11, 1994, implementation date: 199412-01
GB/T 15072.9—94
4.14.2.1 Take two portions of 25.00 ml NazEDTA solution, add 7 ml of tartaric acid solution, 15 ml of ammonium chloride solution, 170 ml of water, 5 drops of xylenol orange solution, add ammonia water (4.5) until the solution changes from yellow to red, add hydrochloric acid (4.4) until the solution changes from red to yellow, add 5 ml of acetic acid-sodium acetate buffer solution, the solution pH is 5.8, titrate with lead nitrate standard titration solution until the solution changes from yellow to red as the end point.
4.14.2.2 Take three portions of 16.00 ml of indium standard solution, and titrate according to the steps in 4.14.2.1. The extreme value of the volume of the standard lead nitrate solution consumed in the two parallel calibrations should not exceed 0.10mL, and the average value is taken. A blank test is performed together with the calibration.
Calculate the actual concentration of the standard lead nitrate solution according to formula (1): mi
C= (V.-V)× 0. 1148
Wherein: c-actual concentration of the standard lead nitrate solution, mol/l; m\-mass of steel removed from the standard indium solution, g; V. —volume of the standard lead nitrate solution consumed by titrating the Na2EDTA solution in the calibration, ml; V. volume of the standard lead nitrate solution consumed by titrating the excess NazEDTA in the standard steel solution, ml.. (1)
0.1148—mass expressed in grams equivalent to 1.00mL of the standard lead nitrate solution (c[Pb(NO)2=1.000mol/L).
4.15 Xylenol orange solution (2g/L).
5 Sample
Process the sample into crumbs, and finally remove the oil with acetone, wash, dry and mix. 6 Analysis steps
6.1 Sample
Weigh about 0.2g of sample, accurate to 0.0001g. Perform two independent determinations and take the average value. 6.2 Determination
6.2.1 Place the sample (6.1) in a 250mlL beaker, heat it with 10ml of mixed acid until it is completely dissolved, remove it, rinse the watch glass and the wall of the beaker with water, evaporate it to nearly dryness, and drip 5 drops of sodium chloride solution. Add 5ml hydrochloric acid solution and evaporate it to nearly dryness, repeat three times. 6.2.2 Add 1mL hydrochloric acid solution, 100mL water, insert a glass rod, cover the surface III, heat to near boiling, add 12mL sulfurous acid, slightly boil for 30min, remove, cool to room temperature. Rinse the surface NM and the cup wall with water. 6.2.3 Add 7mL tartaric acid solution, 15mL ammonium chloride solution, 70mL water, 12mL methyl ethylene dichloride solution, stir, add nitrogen water (4.2) to the solution acidity of pH 8, produce a large amount of red precipitate, let stand for 1h, filter with medium-speed quantitative filter paper, wash the beaker and precipitate with ammonia water (4.6) five times each, and collect the filtrate and washing liquid in a 400mL beaker. 6.2.4 Add 25.00mL Na2EDTA solution and 5 drops of xylenol orange solution to the filtrate, and then add hydrochloric acid solution until the oily red color of the solution just changes to yellow. Then add 5ml of acetic acid-sodium acetate buffer solution. At this time, the pH value of the solution is 5.8. Titrate with standard lead nitrate solution until the solution changes from yellow to red.
7 Expression of analysis results
Calculate the percentage of indium according to formula (2):
In(%) = ×(V:- V)× 0. 114 8 ×X 100
·（2)
GB/T15072.9-94
Wherein: c—actual concentration of standard lead nitrate titration solution, mol/L.; V—volume of standard lead nitrate titration solution consumed by titrating Na?EDTA solution, mlV-volume of standard lead nitrate titration solution consumed by excess Na2EDTA in titration test solution, mL, m. Mass of sample, g;
0.1148—mass in grams equivalent to 1mL of standard lead nitrate titration solution (c[Pb(NO，)J=1.000mol/L) The result should be expressed to the nearest decimal place.
8Tolerance
The difference in analysis results between laboratories should not exceed 0.10%. Additional remarks:
This standard was proposed by China Nonferrous Metals Industry Corporation. This standard was drafted by Kunming Precious Metals Research Institute. This standard was drafted by Kunming Precious Metals Research Institute. The main drafter of this standard was Wu Ruilin.
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