GB/T 15072.17-1994 Chemical analysis methods for precious metals and their alloys - Determination of tungsten content in platinum alloys

GB/T 15072.17-1994 Chemical analysis methods for precious metals and their alloys Determination of tungsten content in platinum alloys GB/T15072.17-1994 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 tungsten content in platinum alloys
Platinum alioys--Determinationof tungsten content
Subject content and scope of application
This standard specifies the determination method of tungsten content in platinum alloys GB/T 15072.17
GR138279
This standard applies to the determination of tungsten content in FPTW8 and PtW8.5 alloys. Determination range: 7%~10% 2 Reference standards
GB1.4 Guidelines for standardization work Provisions for the preparation of chemical analysis method standards GB146? General principles and general provisions for chemical analysis method standards for metallurgical products 3 Summary of the method
The sample is dissolved with mixed acid, tungsten is precipitated as yellow tungstic acid, and the tungsten content is determined by weight. 4 Reagents
4.1 Mixed acid: 3 units of hydrochloric acid (1.19 g/ml) and 1 unit of nitric acid (1.42 g/ml.) are mixed. Prepare 4.2 nitric acid (1-→-9) when needed.
4.3 Silver nitrate solution (10 g/1.).
4.4 Ammonia (1+1).
5 Sample
Add the sample crystal into crumbs, and finally remove the oil with acetone, wash, dry, and mix. 6 Analysis steps
6.1 Sample
Weigh 0.5 g of sample, accurate to 0.0001 g. Perform two independent measurements and take the average value. 6-2 Measurement
6.2.1 Place the sample in a 250 ml beaker, add 20~~30 ml of mixed acid, cover the surface III, and heat at low temperature to dissolve. When dissolving, the mixed acid can be added repeatedly until no black particles are observed, which means it is completely dissolved. Evaporate to about 10mL, remove and cool to room temperature. 6.2.2 Add 30ml of water and filter with double-layer dense ash-free filter paper in a 5cm funnel. Wash the beaker with nitric acid four times, about 6ml each time, and wipe the wall of the cup with a glass rod with a rubber head, and try to transfer the precipitate completely into the funnel. Continue to wash the beaker and precipitate with nitric acid until no chloride is left (test with silver nitrate solution). Transfer the precipitate and filter paper into a constant weight jar. The original beaker is dried at low temperature, and a small piece of ash-free filter paper moistened with ammonia water is used to wipe the tungstic acid adhering to the wall of the cup. Repeat three times. Add the filter paper into the crucible. 6.2.3 Dry the tungsten and the filter paper at low temperature, ash them, and burn them at 850℃ for 20min. Remove them, cool them slightly, and place them in a desiccator for 60min. Weigh them. Burn them again until constant weight.
7 Expression of analysis results
Calculate the percentage of tungsten according to the following formula: www.bzxz.net
W(%)= (mlmz)×0.793.0× 100
Where: m,\—-mass of tungsten trioxide and crucible+g; m is the mass of the crucible.g;
m —mass of the sample, g;
0.7930—factor for converting tungsten trioxide into tungsten. The result should be expressed to two decimal places.
Allowance
The difference in analysis results between laboratories should not exceed 0.10%. Additional remarks:
This standard is 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 drafters of this standard are Guo Qiuquan and Hong Ying.
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