GB/T 15072.18-1994 Methods for chemical analysis of precious metals and their alloys Determination of iron content in gold alloys GB/T15072.18-1994 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 iron content in gold alloys
Gold alloys--Determination of iron content1 Subject content and scope of application
This standard specifies the method for determination of iron content in gold alloys. GB/T 15072.18
This standard is applicable to the determination of iron content in AuNiFeZr9-2-0.3 and AuNiFeZr5-1.5-0.3 alloys. Determination range: 1%~~3% 2 Reference standards
GB1.4 Standardization work guidelines Chemical analysis method standard preparation regulations GB1467 General principles and general provisions of metallurgical product chemical analysis method standards GB7729 Metallurgical product chemical analysis method standard spectrophotometric general rules 3 Method summary
The sample is dissolved in mixed acid, hydrazine is hydrated to separate gold, and at pH 5.5, iron (1) and o-phenanthroline form a red complex, and its absorbance is measured at a wavelength of 510nm on a spectrophotometer. 4 Reagents
4.1 Hydrochloric acid (pl.19g/ml).
4.2 Hydrochloric acid (1+200).
4.3 Mixed acid: Mix 5 units of hydrochloric acid (4.1) with 1 unit of nitric acid (g1.42g/mL). Prepare 4.4 sodium fluoride solution (20g/1.) when using.
4.5 Hydrazine (1+4).
4.6 Mixed color solution: Weigh 2.50g o-phenanthroline and 10g hydroxylamine hydrochloride and dissolve them in a small amount of water. Add 100g crystalline sodium acetate and 25g diammonium hydrogen citrate and dissolve them in about 500mL water. Filter and dilute to 1L with water. 4.7 Iron standard stock solution: Weigh 1.0000g iron and place it in a 150ml beaker, add 25ml hydrochloric acid (4.1). Heat until completely dissolved. Cool, transfer to a 1000ml volumetric flask, add 20ml hydrochloric acid (4.1), dilute to scale with water, and mix well. This solution contains 1mg iron in 1ml. 4.8 Iron standard solution: Transfer 25.00mL of iron standard stock solution to a 500mL volumetric flask, add 15mL hydrochloric acid (1+1), dilute to scale with water, and mix well. This solution contains 50ug iron in 1ml. Approved by the State Administration of Technical Supervision on May 11, 1994 and implemented on December 1, 1994
5 Instrument
Spectrophotometer.
6 Sample
GB/T 15072.18 --- 94
Process the sample into small pieces and remove the iron filings that may be mixed in with a magnet bar. If necessary, use acetone to remove oil stains and clean. Dry and pour into 7 Analysis steps
7.1 Sample
Weigh 0.1g sample to an accuracy of 0.0001g. Perform two independent determinations and take the average value. 7.2 Blank test
Carry out a blank self-test with the sample.
7.3 Determination
7.3.1 Place the sample in a 100ml beaker. Add 10ml of mixed acid, cover the surface III. Heat at low temperature until the sample is completely dissolved. 7.3.2 Add 5ml of sodium chloride solution to the test solution. Evaporate on a low temperature electric stir-fry to about 1ml. Add 5ml of hydrochloric acid (4.1), evaporate until all the gold precipitates. Repeat the evaporation twice, adding 3ml of hydrochloric acid (4.1) each time. 7.3.3 Rinse the surface blood and the wall of the cup with about 20ml of water, and boil for 3~~5min. Wash the surface IIIl and the wall of the cup with a small amount of water. Add hydrated hydrazine dropwise until the gold is completely precipitated (no small bubbles are produced), and add 3-5 drops in excess. Boil to condense the gold. 7.3.4 Cool the solution and filter it with medium-speed filter paper into a 100ml volumetric flask. Wash the filter paper in the beaker with hydrochloric acid (4.2): 1-6 times. Dilute to the scale with a small amount and mix.
7.3.5 Take 10.00ml of the test solution and place it in a 100ml volumetric flask, add about 50ml of water and mix well. Add 15ml of mixed colorimetric solution, dilute to scale with water and mix well. bzxZ.net
7.3.6 Transfer part of the solution into a 1cm absorber, use the blank test solution of the sample as a reference, and measure its absorbance at a wavelength of 510nm on a spectrophotometer. From the working curve, the corresponding amount of iron is obtained. 7.4 Drawing of the working curve
7.4.1 Take 0.0.50.1.00, 2.00, 3.00, 4.00, 5.00, 6.00mL of the iron standard solution and place them in a 100ml volumetric flask respectively, add about 50ml of water, 15mL of mixed colorimetric solution, dilute to scale with water and mix well. 7.4.2 Pipette part of the solution into 1 cm of absorbent blood, use the reagent blank as reference, measure its absorbance at a wavelength of 510 nm on a spectrophotometer, and use the iron content as the horizontal axis and the absorbance as the vertical axis to draw a working curve. 8 Expression of analysis results
Calculate the percentage of iron according to the following formula:
Fe(%) - m. ×VX 10
m, XV
W-volume of the test solution mL;
mass of the test sample·g,
Analysis results are expressed to two decimal places.
9 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in the following table. 122
Additional Notes:
Iron content
1.00~2.00
2.00~3.00
GB/T15072.18—94
This standard is proposed by China Nonferrous Metals Industry Corporation. This standard is drafted by Xianming Precious Metals Research Institute. This standard is drafted by the 621st Research Institute of the Ministry of Aerospace Industry, and the main drafters of this standard are Huang Shumao and Jiang Xiuyu. Allowable difference
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