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GB/T 20975.24-2020: Methods for chemical analysis of aluminium and aluminium alloys - Part 24: Determination of total rare earth content
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Methods for chemical analysis of aluminium and aluminium alloys - Part 24: Determination of total rare earth content
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Methods for chemical analysis of aluminium and aluminium alloys -- Part 24: Determination of total rare earth contents
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Basic data | Standard ID | GB/T 20975.24-2020 (GB/T20975.24-2020) | | Description (Translated English) | Methods for chemical analysis of aluminium and aluminium alloys - Part 24: Determination of total rare earth content | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | H12 | | Classification of International Standard | 77.120.10 | | Word Count Estimation | 10,162 | | Date of Issue | 2020-06-02 | | Date of Implementation | 2021-04-01 | | Older Standard (superseded by this standard) | GB/T 20975.24-2008 | | Quoted Standard | GB/T 8005.2; GB/T 8170-2008; GB/T 15676 | | Issuing agency(ies) | State Administration for Market Regulation, China National Standardization Administration | | Summary | This standard specifies the determination of the total content of rare earth elements in the cerium group in aluminum and aluminum alloys by spectrophotometry and oxalate gravimetry. This standard applies to the arbitration determination of the total content of cerium group rare earth elements in aluminum and aluminum alloys. Determination range of arsenine tribromide by spectrophotometry: 0.001 0%��2.50%; Determination range of oxalate gravimetric method: 1.50%��16.00%. When the total content of rare earth elements in the cerium group is >1.50% to 2.50%, the oxalate gravimetric method is used as the arbitration method. | GB/T 20975.24-2020: Methods for chemical analysis of aluminium and aluminium alloys - Part 24: Determination of total rare earth content
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Methods for chemical analysis of aluminium and aluminium alloys--Part 24.Determination of total rare earth content
ICS 77.120.10
H12
National Standards of People's Republic of China
Replace GB/T 20975.24-2008
Chemical analysis methods of aluminum and aluminum alloys
Part 24.Determination of total rare earth content
2020-06-02 released
Implementation on 2021-04-01
State Administration for Market Regulation
Issued by the National Standardization Management Committee
Foreword
GB/T 20975 "Methods for Chemical Analysis of Aluminum and Aluminum Alloys" is divided into 37 parts.
---Part 1.Determination of mercury content;
---Part 2.Determination of arsenic content;
---Part 3.Determination of copper content;
---Part 4.Determination of iron content;
---Part 5.Determination of silicon content;
---Part 6.Determination of cadmium content;
---Part 7.Determination of manganese content;
---Part 8.Determination of zinc content;
---Part 9.Determination of lithium content by flame atomic absorption spectrometry;
---Part 10.Determination of tin content;
---Part 11.Determination of lead content;
---Part 12.Determination of titanium content;
---Part 13.Determination of vanadium content;
---Part 14.Determination of nickel content;
---Part 15.Determination of boron content;
---Part 16.Determination of magnesium content;
---Part 17.Determination of strontium content;
---Part 18.Determination of chromium content;
---Part 19.Determination of Zirconium Content;
---Part 20.Determination of Gallium Content Butyl Rhodamine B Spectrophotometry;
---Part 21.Determination of calcium content;
---Part 22.Determination of beryllium content;
---Part 23.Determination of antimony content;
---Part 24.Determination of total rare earth content;
---Part 25.Determination of element content by inductively coupled plasma atomic emission spectrometry;
---Part 26.Determination of carbon content by infrared absorption method;
---Part 27.Determination of cerium, lanthanum and scandium content by inductively coupled plasma atomic emission spectrometry;
---Part 28.Determination of cobalt content by flame atomic absorption spectrometry;
---Part 29.Determination of molybdenum content thiocyanate spectrophotometric method;
---Part 30.Determination of hydrogen content by heating extraction thermal conductivity method;
---Part 31.Determination of phosphorus content molybdenum blue spectrophotometric method;
---Part 32.Determination of Bismuth Content;
---Part 33.Determination of potassium content by flame atomic absorption spectrometry;
---Part 34.Determination of sodium content by flame atomic absorption spectrometry;
---Part 35.Determination of Tungsten Content Thiocyanate Spectrophotometric Method;
---Part 36.Determination of silver content by flame atomic absorption spectrometry;
--- Part 37.Determination of Niobium Content.
This part is part 24 of GB/T 20975.
This section was drafted in accordance with the rules given in GB/T 1.1-2009.
This part replaces GB/T 20975.24-2008 "Methods for Chemical Analysis of Aluminum and Aluminum Alloy Part 24.Determination of Total Rare Earth Content",
Compared with GB/T 20975.24-2008, the main technical changes except for editorial changes are as follows.
--- Added standard use safety warnings;
--- Added "Normative Reference Documents" (see Chapter 2);
--- Added "Terms and Definitions" (see Chapter 3);
---Added requirements for reagents and water used in analysis (see 4.2 and 5.2);
---Modified the measurement range of tribromoarsenazo spectrophotometry, adjusted from 0.0010%~1.50% to 0.0010%~2.50%
(See Chapter 1, Chapter 1 of the.2008 edition);
---Modified the measurement range in the oxalate gravimetric method, adjusted from >1.50% to 1.50%~16.00% (see Chapter 1,.2008 edition
Chapter 10);
---Modified the amount of tribromoarsenazo used in the tribromoarsenazo spectrophotometric method (see Table 1,.2008 version of 6.4.3);
---Modified the precipitant in the oxalate weight method, adjusted from oxalate acetone solution to oxalate ethanol solution (see 5.2.5,.2008 edition
12.5);
---Modified the acidity indicator in the oxalate weight method, adjusted from thymol blue ethanol solution to cresol red ethanol solution (see 5.2.7,
12.6 of the.2008 edition);
---Modified the sample dissolution method in the oxalate gravimetric method and added hydrogen peroxide (see 5.5.3.1, 15.3.1 in the.2008 edition);
---Modified the oxalate weight method from natural cooling to room temperature and adjusted it to be removed and placed for more than 2 hours (see 5.5.3.2,.2008 edition
15.3.2);
---Modified the oxalate weight method "washing the beaker with oxalic acid lotion and precipitation 7 to 8 times each" and adjusted it to washing with oxalic acid lotion.
Cup 3 times, wash precipitation 7 to 8 times (see 5.5.3.2, 15.3.2 of the.2008 edition);
---The burning temperature of the high-temperature furnace in the oxalate gravimetric method is modified from 900℃ to 950℃ (see 5.5.3.3,.2008 edition
15.3.3);
--- Deleted "Quality Assurance and Control" (see Chapter 9 and Chapter 18 of the.2008 edition);
--- Added "Test Report" (see Chapter 6).
This part was proposed by China Nonferrous Metals Industry Association.
This part is under the jurisdiction of the National Nonferrous Metals Standardization Technical Committee (SAC/TC243).
Drafting organizations of this section. Baotou Aluminum Co., Ltd., National Standard (Beijing) Inspection and Certification Co., Ltd., Non-ferrous Metals Technology and Economic Research Institute, Dongfang
North Light Alloy Co., Ltd., Chinalco Zhengzhou Nonferrous Metal Research Institute Co., Ltd., Agri-Yijin New Materials Co., Ltd., Standard Technology
Service (Tianjin) Co., Ltd., Changsha Research Institute of Mining and Metallurgy Co., Ltd., Beikuang Testing Technology Co., Ltd., South China University of Technology.
The main drafters of this section. Shen Li, Zhang Xiaoping, Gao Baotang, Bao Yelin, Li Fengyan, Zhang Wan, Xi Huan, Zhou Bing, Han Xiao, Wu Yuqiang, Hu Xuan,
Liu Chaofang, Yan Lixin, Liu Zhengda, Liu Chunfeng, Dai Fengying, Guo Yanping, Shan Xin, Zhang Zhiheng.
The previous versions of the standards replaced by this part are as follows.
---GB/T 6987.24-1988, GB/T 6987.24-2001;
---GB/T 6987.32-2001;
---GB/T 20975.24-2008.
Chemical analysis methods of aluminum and aluminum alloys
Part 24.Determination of total rare earth content
Warning---Personnel using this section should have practical experience in formal laboratory work. This section does not point out all possible safety issues
question. The user is responsible for taking appropriate safety and health measures and ensuring compliance with the conditions stipulated by relevant national laws and regulations.
1 Scope
This part of GB/T 20975 specifies the tribromoarsenazo spectrophotometric method and the oxalate gravimetric method for the determination of cerium group rare earths in aluminum and aluminum alloys
The total content of elements.
This section applies to the arbitration determination of the total content of rare earth elements in the cerium group in aluminum and aluminum alloys. Spectrophotometric determination range of tribromoarsenazo.
0.0010%~2.50%; oxalate gravimetric method determination range. 1.50%~16.00%.
When the total content of rare earth elements in the cerium group is greater than 1.50% to 2.50%, the oxalate weight method is used as the arbitration method.
2 Normative references
The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article
Pieces. For undated references, the latest version (including all amendments) applies to this document.
GB/T 8005.2 Terminology of Aluminum and Aluminum Alloy Part 2.Chemical Analysis
GB/T 8170-2008 Numerical rounding rules and the expression and determination of limit values
GB/T 15676 Rare earth terms
3 Terms and definitions
The terms and definitions defined in GB/T 8005.2 and GB/T 15676 apply to this document.
4 Tribromoarsenazo spectrophotometry
4.1 Method summary
The sample is dissolved in hydrochloric acid, and hydrogen peroxide and ethanol are used to eliminate the coexistence of tetravalent titanium ions and trivalent iron ions in a hydrochloric acid-oxalic acid medium.
Interference, the rare earth elements of the cerium group and tribromoarsenazo form a stable blue-violet complex, and the absorption is measured at a wavelength of 634.0nm with a spectrophotometer.
Photometric, to determine the total content of rare earth elements in the cerium group.
4.2 Reagents
Unless otherwise stated, only reagents and laboratory secondary water confirmed to be analytically pure are used in the analysis.
4.2.1 Anhydrous ethanol.
4.2.2 Hydrochloric acid (1 1).
4.2.3 Hydrogen peroxide (1 19).
4.2.4 Oxalic acid (H2C2O4·2H2O) solution (80g/L).
4.2.5 Aluminum solution (20mg/mL). Weigh 20.00g pure aluminum (wAl≥99.99%, wRE≤0.0010%) into a 1000mL beaker, cover
On the table dish, add 600mL hydrochloric acid (4.2.2) in batches. Slowly heat until the dissolution is complete, remove and cool. Transfer to 1000mL volume
In a measuring flask, dilute to the mark with water and mix well.
4.2.6 Tribromoarsenazo [2-(2-arsinoylphenylazo)-7-(2,4,6-tribromophenylazo)-1,8-dihydroxy-3,6-naphthalene Disulfonic acid] solution
(0.5g/L).
4.2.7 Cerium standard storage solution. use a certified standard solution to prepare. Or weigh 0.6142g cerium oxide [w(CeO2)≥99.9%,
Burn in a high temperature furnace at 800℃~900℃ for 30min in advance, take it off a little cold, and place it in a desiccator for 60min before weighing], accurate to
0.0001g, placed in a.200mL beaker, add 5mL perchloric acid (ρ=1.67g/mL), 2mL hydrogen peroxide (ρ=1.10g/mL),
Cover with a watch glass, heat at low temperature until the cerium oxide is completely dissolved, and evaporate to nearly dry. Remove, cool slightly, add 50mL hydrochloric acid (4.2.2), 6 drops
Hydrogen oxide (4.2.3), heat and boil to completely dissolve the salts and completely decompose the hydrogen peroxide, remove it, cool to room temperature, and transfer to 500mL capacity
In the bottle, add 35mL hydrochloric acid (4.2.2), dilute to the mark with water, and mix. 1mL of this solution contains 1mg of cerium.
Note. Under the measurement conditions of this part, the absorbance of the complex formed by cerium or cerium group rare earth elements and tribromoarsenazo is the same, so cerium can be used instead of cerium group rare earth elements
The total amount of vegetarian is the standard.
4.2.8 Cerium standard solution A. Pipette 5.00mL cerium standard stock solution (4.2.7) into a 250mL volumetric flask, add 40mL hydrochloric acid
(4.2.2), dilute to the mark with water, and mix well (prepared when used). This solution 1mL contains 20μg cerium.
4.2.9 Cerium standard solution B. Pipette 50.00mL cerium standard solution A (4.2.8) into a 500mL volumetric flask, dilute to the mark with water, and mix well
(Now equipped when used). 1mL of this solution contains 2μg of cerium.
4.2.10 Cerium standard solution C. Pipette 1.00mL cerium standard stock solution (4.2.7) into a 100mL volumetric flask, add 40mL hydrochloric acid
(4.2.2), dilute to the mark with water, and mix well (prepared when used). 1mL of this solution contains 10μg of cerium.
4.3 Apparatus
Spectrophotometer.
4.4 Sample
Process the sample into chips with a thickness of not more than 1mm.
4.5 Analysis steps
4.5.1 Sample
According to the total content of rare earth elements in the cerium group, weigh a sample (4.4) of the corresponding mass (m0) according to Table 1, accurate to 0.0001g.
4.5.2 Parallel test
Do two tests in parallel and take the average value.
4.5.3 Blank test
Pipette 5.0mL aluminum solution (4.2.5) in a 25mL volumetric flask (or colorimetric tube), the following operations are performed according to 4.5.4.3.
4.5.4 Determination
4.5.4.1 Place the sample (4.5.1) in a 300mL beaker, cover with a watch glass, and add 30mL hydrochloric acid (4.2.2) in batches at low temperature.
Heat until the sample is completely dissolved, remove, cool, filter with medium speed filter paper in a volumetric flask corresponding to the volume of the test solution shown in Table 1, and purge the beaker
And filter paper 5 to 8 times each, dilute to the mark with water, and mix well.
4.5.4.2 Pipette the test solution (4.5.4.1) into a 25mL volumetric flask (or colorimetric tube) according to Table 1, and add a corresponding volume of aluminum solution
(4.2.5).
4.5.4.3 Add 2mL hydrochloric acid (4.2.2), 2mL oxalic acid solution (4.2.4), 2mL absolute ethanol (4.2.1), 3 drops of hydrogen peroxide (4.2.3),
Shake well. Add the corresponding volume of tribromoarsenazo solution (4.2.6) in Table 1, dilute to the mark with water, and mix.
4.5.4.4 Place part of the test solution (4.5.4.3) in the corresponding absorption cell, and use the blank test (4.5.3) solution as the reference, and set the wavelength at the spectrophotometer wavelength
The absorbance was measured at 634.0nm. Find the total amount of rare earth elements in the cerium group (m1) from the working curve.
4.5.5 Drawing of working curve
4.5.5.1 According to the mass fraction of rare earth elements in the cerium group, the preparation of the working curve series standard solution is divided into the following three types.
a) When the mass fraction of rare earth elements in the cerium group is 0.0010%~0.10%. add each in a set of 25mL volumetric flasks (or colorimetric tubes)
5.0mL aluminum solution (4.2.5), add 0mL, 0.50mL, 1.00mL, 2.50mL, 3.50mL, 5.00mL cerium respectively
Standard solution B (4.2.9), the following operations are performed according to 4.5.4.3.
b) When the mass fraction of rare earth elements in the cerium group is >0.10%~0.60%. add each in a set of 25mL volumetric flasks (or colorimetric tubes)
5.0mL aluminum solution (4.2.5), add 0mL, 1.00mL, 2.50mL, 5.00mL, 6.50mL, 7.50mL cerium respectively
Standard solution B (4.2.9), the following operations are performed according to 4.5.4.3.
c) When the total mass fraction of rare earth elements in the cerium group is >0.60%~2.50%. add each in a set of 25mL volumetric flasks (or colorimetric tubes)
5.0mL aluminum solution (4.2.5), add 0mL, 0.50mL, 1.00mL, 1.50mL, 2.00mL, 2.50mL cerium standard
Solution C (4.2.10), the following operations are performed according to 4.5.4.3.
4.5.5.2 Place part of the series of standard solutions (4.5.5.1) in the corresponding absorption pool, and use the reagent blank solution (without the cerium standard solution) as
For reference, the absorbance is measured at a wavelength of 634.0nm with a spectrophotometer, and the mass of cerium is used as the abscissa and the absorbance is the ordinate.
curve.
4.6 Test data processing
The total content of rare earth elements in the cerium group is calculated by the mass fraction wRE of the cerium group rare earth elements, calculated according to formula (1).
When the mass fraction of the total rare earth elements of the cerium group is ≥1.00%, the calculation result is expressed to two digits after the decimal point; the total amount of the rare earth elements of the cerium group
When the quality score of < 1.00%, the calculation result retains two significant digits. The rounding of values shall be implemented in 3.2 and 3.3 of GB/T 8170-2008.
4.7 Precision
4.7.1 Repeatability
The measured values of two independent test results obtained under repeatability conditions, within the average range given below, these two test results
The absolute difference of r does not exceed the repeatability limit r, and the repeatability limit r does not exceed 5%. The repeatability limit r is linear according to the data in Table 2.
Obtained by interpolation.
4.7.2 Tolerance
The difference between the analysis results between laboratories should not be greater than the allowable difference listed in Table 3.
5 Oxalate weight method
5.1 Method summary
Dissolve the sample with sodium hydroxide solution to separate interference elements such as Al, Mg, Ca, Zn, Si, etc., and dissolve it with oxalic acid ethanol under pH 2.0
The solution is used as a precipitant to precipitate rare earths, and the formed rare earth oxalate is burned into rare earth oxides at 950℃. According to the proportion of rare earth contained in the sample
Calculate the conversion coefficient of rare earth metals and their oxides, and calculate the total content of rare earth elements in the cerium group.
5.2 Reagents
Unless otherwise stated, only reagents and laboratory secondary water confirmed to be analytically pure are used in the analysis.
5.2.1 Hydrogen peroxide (ρ=1.10g/mL).
5.2.2 Ammonia (ρ=0.91g/mL).
5.2.3 Hydrochloric acid (1 1).
5.2.4 Sodium hydroxide solution (200g/L).
5.2.5 Oxalic acid ethanol solution (40g/L). Weigh 40g of oxalic acid and dissolve it in 1L of absolute ethanol.
5.2.6 Oxalic acid lotion (2g/L). Dissolve 2g of oxalic acid in 1L of water.
5.2.7 Cresyl red ethanol solution (2g/L). Dissolve 0.2g of cresyl red in 50mL of absolute ethanol, add water to 100mL.
5.3 Apparatus and equipment
High temperature furnace. The temperature can be controlled at 950℃±10℃.
5.4 Sample
Process the sample into chips with a thickness of not more than 1mm.
5.5 Analysis steps
5.5.1 Sample
Weigh the mass (m2) as 1.00g sample (5.4), accurate to 0.0001g.
5.5.2 Parallel test
Do two tests in parallel and take the average value.
5.5.3 Determination
5.5.3.1 Place the sample (5.5.1) in a 300mL beaker, cover with a watch glass, add 40mL sodium hydroxide solution (5.2.4), and wait until the violent reaction stops.
After stopping, add 3mL hydrogen peroxide (5.2.1) dropwise, continue to heat and boil until the hydrogen peroxide is completely decomposed, add 100mL hot water, and boil for 1min.
Remove it slightly cold, filter with a slow quantitative filter paper, and wash the precipitate with hot water to pH 7~8.
5.5.3.2 Transfer the precipitate and filter paper into the original beaker, add 5 mL of hydrochloric acid (5.2.3), 3 mL of hydrogen peroxide (5.2.1), and heat to precipitate
Dissolve, mash the filter paper with a glass rod, and continue to boil until there are no small bubbles. Add 120mL of hot water, boil, remove and cool a little, while it is still hot, keep stirring
Add 20mL oxalic acid ethanol solution (5.2.5) under stirring, add 2 to 3 drops of cresol red ethanol solution (5.2.7), use ammonia (5.2.2) and hydrochloric acid
(5.2.3) After adjusting the pH to 1.8~2.2 (precision pH test paper), keep it in a water bath at 80℃ for 1 hour, and then take it off and leave it for more than 2 hours. Use slow
Filter with quantitative filter paper, wash the beaker 3 times with oxalic acid lotion (5.2.6), and wash the precipitate 7 to 8 times. Transfer the filter paper and sediment to a constant weight
In an empty platinum crucible or porcelain crucible (m3), ash on an electric furnace.
5.5.3.3 Burn in a high-temperature furnace at 950°C for 1 hour, take it out, and place it in a desiccator to cool for 1 hour before weighing (m4) to constant weight.
5.6 Test data processing
The total amount of rare earth elements in the cerium group is calculated by the mass fraction wRE of the cerium group rare earth elements, calculated according to formula (2).
The calculation result is expressed to two digits after the decimal point. The rounding of values shall be implemented in 3.2 and 3.3 of GB/T 8170-2008.
5.7 Precision
5.7.1 Repeatability
The measured value of two independent test results obtained under repeatability conditions, within the average range given below, these two test results
The absolute difference does not exceed the repeatability limit r, and the repeatability limit r does not exceed 5%. The repeatability limit r is within the linear range according to the data in Table 4.
Obtained by interpolation or extension method.
5.7.2 Reproducibility
The measured values of two independent test results obtained under reproducibility conditions are within the average range given below. These two test results
The absolute difference does not exceed the reproducibility limit R, and the reproducibility limit R does not exceed 5%. The reproducibility limit R is linear according to the data in Table 5.
Obtained by interpolation or extension.
6 Test report
The test report should include the following.
a) The number, name and method used in this section;
b) All necessary information about identification of samples, laboratory, analysis date, report date, etc.;
c) Express the test results in an appropriate form;
d) Abnormal phenomena during the test;
e) Signatures of review and approval personnel.
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