This standard specifies the method for determining the gadolinium content in gold alloys. This standard is applicable to the determination of the gadolinium content in AuAgCuGd35-5-0.4 and AuAgCuMnGd33.5-3-2.5-0.4 alloys. Determination range: 0.3% to 0.6%. GB/T 15072.11-1994 Chemical analysis methods for precious metals and their alloys Determination of gadolinium content in gold alloys GB/T15072.11-1994 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 gadolinium content in gold alloys
Gold alloys-- Determination of gadolinium content1 Subject content and scope of application
This standard specifies the method for determining the vanadium content in gold alloys. GB/T 15072. 11- 94
This standard is applicable to the determination of the content in AuAgCuGd35-5-0.4 and AuAgCuMnGd33.5-3-2.5-0.4 alloys. Determination range: 0.3%~0.6%.
2 Reference standards
GB1.4 Standardization work guidelines Chemical analysis method preparation regulations GB1467 General principles and general provisions of metallurgical product chemical analysis method standards GB7729 General principles of spectrophotometric methods for chemical analysis of metallurgical products 3 Method summary
The sample is dissolved in mixed acid, and silver is separated by silver chloride precipitation. In a buffer solution with a pH of 1.5, (III) reacts with azochlorophosphine III to form a blue complex, and its absorbance is measured at a wavelength of 680nm on a spectrophotometer. The interference of gold and copper is masked by sulfur gland 4 Reagents
4.1 Mixed acid: 1 unit volume of nitric acid (p1.42g/mL) and 6 unit volumes of hydrochloric acid (p1.19g/mL) are mixed. Prepare freshly when used. 4.2 Hydrochloric acid (1+1).
4.3 Hydrochloric acid (1+99).
4.4 Thiourea solution (100/L).
4.5 Buffer solution: Weigh 10g potassium hydrogen phthalate, dissolve it in about 2.2L water, add 25mL hydrochloric acid (4.2), dilute to 2.5L with water, adjust its pH to 1.50 (measured with a pH meter) with hydrochloric acid (4.2) and as little sodium hydroxide solution (200g/L) as possible. 4.6 Chlorophosphonazo solution (0.2g/L).
4.7 Standard stock solution: Weigh 0.2882g oxide (Gd.0>99.9%) and place it in a 50mL beaker. Add 4.2mL hydrochloric acid (p1.19g/mL) and heat at low temperature to dissolve. Cool, transfer to a 250mlL volumetric flask, dilute to scale with water, and mix well. This solution contains 1mg in 1mL.
4.8 Vanadium standard solution: Pipette 2.50 mL of standard stock solution into a 250 mL volumetric flask, dilute to scale with water, and mix. This solution contains 10 μg in 1 ml. Prepare on the same day.
4.9 Gold-copper solution: Add the following amount of metal chloride solution, 600 mg gold, 50 mg copper, into a 500 mL volumetric flask, dilute to scale with 0.1 mol/I hydrochloric acid, and mix.
4.10 Gold-copper-manganese solution: Add the following amount of metal chloride solution to a 500mL volumetric flask: 600mg gold, 30mg copper, 25mg manganese, dilute to scale with 0.1mol/L hydrochloric acid, and mix well. Approved by the State Administration of Technical Supervision on May 11, 1994 and implemented on December 1, 1994
GB/T 15072.11 94
Note: The above solution must be clear. If there is precipitation, it should be filtered before use. 5 Instruments
Spectrophotometer.
6 Sample
The sample is processed into crumbs, and finally washed with acetone to remove oil, dried, and mixed. 7 Analysis steps
7.1 Sample
Weigh about 0.1g of sample to the nearest 0.0001g, and measure twice independently, taking the average value. 7.2 Blank test
Carry out a blank test with the sample. However, for gold-silver-copper alloy samples, the blank should be added with gold-copper solution (4.9); for gold-silver-copper-manganese gold-containing samples, the blank should be added with gold-copper-manganese solution (4.10). 7.3 Determination
7.3.1 Place the sample (7.1) in a 250mL beaker, cover it with surface blood, add 50ml. mixed acid and heat at low temperature until completely dissolved, remove it, rinse the surface blood and the wall of the beaker with water, and evaporate to nearly dry. Add 5mL hydrochloric acid (4.2) and evaporate to nearly dry, repeat three times. 7.3.2 Add 10mL hydrochloric acid (4.3) to dissolve, filter the silver chloride precipitate with medium-speed filter paper, wash the precipitate and filter paper with hydrochloric acid (4.3) until the filtrate is colorless, and then wash three times. Collect the filtrate in a 50mL volumetric flask. Dilute to scale with hydrochloric acid (4.3) and mix well. 7.3.3 Take 5.00 ml of the test solution and place it in a 25 mL beaker. Steam until it is nearly dry. Dissolve the residue with 25 mL of buffer solution in batches. Wash and transfer to a 50 mL volumetric flask.
7.3.4 Add 1 mL of thiourea solution. Be careful to rinse the bottle mouth with water until the total volume of the solution is about 35-40 ml. Mix well. Add 8.00 ml of azochlorophosphine solution. Dilute to the mark with water and mix well. 7.3.5 Transfer part of the solution into a 2 cm absorption III. Use the blank accompanying the sample as a reference and measure its absorbance at a wavelength of 680 nm on a spectrophotometer. Obtain the vanadium content from the working curve. 7.4 Drawing of working curve
7.4.1 For the corresponding gold, silver, copper, vanadium or gold, silver, copper, manganese test solution, transfer 5 ml of gold-copper solution (4.9) or gold-copper-manganese solution (4.10) to a group of 25 ml beakers, evaporate to near dryness, dissolve with 25 ml of buffer solution in batches, wash, and transfer to a group of 50 ml volumetric flasks. Then transfer 0, 1.00, 2.00, 3.00, 4.00, 5.00 ml of standard solution to the group of volumetric flasks in turn. The following is carried out according to 7.3.4. 7.4.2 Transfer part of the solution to 2 cm absorption blood, use the compensation solution as reference, and measure its absorbance at a wavelength of 680 nm on a spectrophotometer.
7.4.3 Draw the working curve with the amount as the horizontal axis and the absorbance as the vertical axis. 8 Expression of analysis results
Calculate the percentage of vanadium by the following formula:
Gd(%) = m × Vo× 10-
The amount found from the working curve, g;
Where: m——
Total volume of test solution, mL;bZxz.net
V,--Volume of test solution taken, mL.;
mThe mass of the test material.
The result should be expressed to two decimal places.
9 Allowable difference
GB/T 15072.11-94
The difference in analysis results between laboratories should not exceed 0.04%. 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 is Wu Ruilin.
From the date of implementation of this standard, the former Ministry of Metallurgical Industry Standard YB946 (Au-15)--78 "Chemical Analysis Methods for Gold, Silver, Copper and Manganese Alloys" shall be invalid.
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