This standard specifies the method for determining the chromium content in copper and copper alloys. This standard is applicable to the determination of chromium content in copper and copper alloys. Determination range: 0.050% to 1.30%. GB/T 5121.16-1996 Chemical analysis method for copper and copper alloys Determination of titanium content GB/T5121.16-1996 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis methods for copper and copper alloys
Determination of chromium content
Copper and copper alloys--Determination of chromium content1 Scope
This standard specifies the method for determining the chromium content in copper and copper alloys. This standard is applicable to the determination of chromium content in copper and copper alloys. Determination range: 0.050%~~1.30%. 2 Referenced standards
GB/T 5121.16 -1996
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. At the time of publication of this standard, the versions shown are valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB1.4·88 Guidelines for Standardization Work Provisions for the Preparation of Chemical Analysis Methods GB146778 General Principles and General Provisions for Chemical Analysis Methods for Metallurgical Products GB7728-87 General Principles for Flame Atomic Absorption Spectrometry for Chemical Analysis of Metallurgical Products 3 Method Summary
The sample is dissolved in nitric acid, sulfuric acid and hydrofluoric acid. In a dilute sulfuric acid medium, sodium sulfate is used as an interference inhibitor for zirconium, manganese and other elements. Then, acetylene flame is used to measure the absorbance of chromium at a wavelength of 357.9nm on an atomic absorption spectrometer. 4 Reagents
4.1 Nitric acid (pl.42g/mL), high-grade purity. 4.2 Sulfuric acid (ol.84g/ml.)). High-grade purity. 4.3 Hydrofluoric acid (pl.15g/mL).
4.4 Hydrogen peroxide (30%).
4.5 Nitric acid (1+1).
4.6 Sodium sulfate solution (100g/L).
4.7 Chromium standard solution: Weigh 0.1414g potassium dichromate standard reagent that has been dried at 140℃ and cooled in a desiccator, place in a 100ml beaker, dissolve in 10ml water, add 5ml sulfuric acid (4.2), cool, drop hydrogen peroxide (4.4), add 2ml excess after boiling stops, leave for more than 4h until the yellow color disappears, transfer to a 1000mL volumetric flask, dilute to scale with water, and mix 1ml of this solution with 50 μg chromium.
5 Instruments
Atomic absorption spectrometer with chromium hollow cathode lamp. Under the best working conditions of the instrument, the characteristic concentration can be used by those who can achieve the following indicators: In the solution consistent with the matrix of the measured solution, the characteristic concentration of chromium should not be less than (.1ug/ml. Precision: The standard deviation of the absorbance measured 10 times with the highest concentration standard solution should not exceed 1.5 real of the average absorbance; the standard concentration of chromium ... 16—1996
Measure the absorbance of the low-concentration standard solution (not the "zero" standard solution) 10 times, and its standard deviation should not exceed 0.5% of the average absorbance of the highest concentration standard solution.
Working curve linearity: Divide the working curve into 5 sections according to concentration. The ratio of the absorbance difference of the highest section to the absorbance difference of the lowest section should not be less than 0.7.
Instrument working conditions are shown in Appendix A (Suggested Appendix). 6 Analysis steps
6.1 Test material
Weigh the sample according to Table 1, accurate to 0.0001g. Table
Amount, %
0.050~~0.30
>0. 30~1. 30
Carry out two independent determinations and take the average value. 6.2 Blank test
Carry out a blank test with the sample.
6.3 Determination
Quantity·Multiple
Take a test solution volume of .ml.
6.3.1 Place the sample (6.1) in a 200ml beaker, cover with a watch glass, add 5ml. nitric acid (4.5), dissolve at low temperature and evaporate to a volume of about 2mL, add 6ml. sulfuric acid, 0.5mL hydrofluoric acid, evaporate until white smoke appears, add 3~5ml. nitric acid (4.1) dropwise while hot, wait for the violent reaction to be completed, remove the watch glass, continue to evaporate until white smoke appears, cool, add 10rmL of water to dissolve the salt, transfer to a 100mL volumetric flask, dilute to the scale with water, and mix well.
6.3.1.1 When the chromium content is 0.05%~0.30%, transfer the solution according to Table 1 Liquid in another 100mL volumetric flask, add 1mL sodium sulfate solution, dilute to the scale with water, and mix.
6.3.1.2 When the chromium content is greater than 0.30%~1.30%, transfer the solution according to Table 1 to another 100mL volumetric flask, add 0.6mL sulfuric acid and 4mL sodium sulfate solution, dilute to the scale with water, and mix. 6.3.2 Using an air-acetylene flame, at a wavelength of 357.9nm on the atomic absorption spectrometer, adjust to zero with water at the same time as the standard solution series, and measure the absorbance of the sample solution. Subtract the absorbance of the empty solution accompanying the sample, and find the corresponding chromium concentration from the working curve. 6.4 Drawing of the working curve
6.4.1 Transfer 0, 1.00, 2.00, 3.00, 4.00, 5.00, 6.00mL of chromium standard solution and place them in a group of 100mL volumetric flasks respectively. Add 1 ml sulfuric acid, 4 mL sodium sulfate solution, dilute to scale with water, and mix. 6.4.2 Under the same conditions as the test solution, measure the absorbance of the standard solution series, subtract the absorbance of the 1" concentration solution in the standard solution series, and draw a working curve with chromium concentration as the horizontal axis and absorbance as the vertical axis. Expression of analysis results
Calculate the white content of chromium according to formula (1):
Cr(%) - cV, .V.× 10 6
Wherein: (——chromium concentration obtained from the T curve, ug/mLV..-total volume of test solution, mL;
V.—volume of the diluted test solution.ml; V. volume of the test solution.mI.;
mass of the test material, g.
GB/T5121.16—1996
The results are expressed to two decimal places. If the chromium content is less than 0.10%, it is expressed to three decimal places. Allowable difference
The difference between the analysis results of different laboratories shall not exceed the allowable difference listed in Table 2. Table 2bzxZ.net
0. 050~~0. 30
>0. 60~1. 30
GB/T5121.16
Appendix A
(Prompt Request)
Instrument Working Conditions
The working conditions for determining the amount of chromium using a WFX-11) atomic absorption spectrometer are shown in Table A1. Table A1
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