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GB/T 20975.35-2020: Methods for chemical analysis of aluminium and aluminium alloys - Part 35: Determination of tungsten content--Thiocyanate spectrophotometric method
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Methods for chemical analysis of aluminium and aluminium alloys - Part 35: Determination of tungsten content--Thiocyanate spectrophotometric method
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GB/T 20975.35-2020
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Basic data | Standard ID | GB/T 20975.35-2020 (GB/T20975.35-2020) | | Description (Translated English) | Methods for chemical analysis of aluminium and aluminium alloys - Part 35: Determination of tungsten content--Thiocyanate spectrophotometric method | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | H12 | | Classification of International Standard | 77.120.10 | | Word Count Estimation | 6,653 | | Date of Issue | 2020-06-02 | | Date of Implementation | 2021-04-01 | | Quoted Standard | GB/T 8005.2; GB/T 8170-2008 | | Issuing agency(ies) | State Administration for Market Regulation, China National Standardization Administration | | Summary | This standard specifies the determination of tungsten content in aluminum and aluminum alloys by thiocyanate spectrophotometry. This standard applies to the arbitration determination of tungsten content in aluminum and aluminum alloys. Determination range of thiocyanate spectrophotometry: 0.15% to 5.00%. This standard does not apply to aluminum and aluminum alloys with a mass fraction of tungsten greater than 0.0050%. | GB/T 20975.35-2020: Methods for chemical analysis of aluminium and aluminium alloys - Part 35: Determination of tungsten content--Thiocyanate spectrophotometric method
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Methods for chemical analysis of aluminium and aluminium alloys--Part 35.Determination of tungsten content--Thiocyanate spectrophotometric method
ICS 77.120.10
H12
National Standards of People's Republic of China
Chemical analysis methods of aluminum and aluminum alloys
Part 35.Determination of Tungsten Content
Thiocyanate Spectrophotometry
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 35 of GB/T 20975.
This section was drafted in accordance with the rules given in GB/T 1.1-2009.
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. Guangdong Industrial Analysis and Testing Center, Non-ferrous Metal Technology and Economic Research Institute, Xi'an Hantang Analysis and Testing Co., Ltd.
Division, Guizhou Institute of Analysis and Testing, Beikuang Testing Technology Co., Ltd., Kunming Metallurgical Research Institute, Hebei Sitong New Metal Materials Co., Ltd.
The company, Shaoguan City, Guangdong Province, Quality and Metrology Supervision and Inspection Institute, Northeast Light Alloy Co., Ltd.
The main drafters of this section. Xie Hui, Li Yuhong, Zhang Sheng, Xi Huan, Wang Jinlei, Li Jiahua, Xiong Xiaoyan, Zhou Bing, Ma Xuewen, Liu Weili, Xin Jing,
Yuan Qi, Luo Lin, Shi Hongjuan, Yu Fuxing, Guo Jun, Zhang Yapei.
Chemical analysis methods of aluminum and aluminum alloys
Part 35.Determination of Tungsten Content
Thiocyanate Spectrophotometry
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 thiocyanate spectrophotometric method for the determination of tungsten content in aluminum and aluminum alloys.
This section applies to the arbitration determination of tungsten content in aluminum and aluminum alloys. Determination range of thiocyanate spectrophotometry. 0.15%~5.00%.
This section does not apply to aluminum and aluminum alloys with a mass fraction of tungsten greater than 0.0050%.
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
3 Terms and definitions
The terms and definitions defined in GB/T 8005.2 apply to this document.
4 Method summary
The sample is decomposed by sodium hydroxide and hydrogen peroxide. Dissolve salts with water to separate tungsten from most metal elements. In hydrochloric acid medium
In, using tin dichloride-titanium trichloride solution to reduce tungsten element to tungsten (V) and thiocyanate to form a yellow complex, at the wavelength of the spectrophotometer
Measure its absorbance at 404nm to determine the tungsten content.
5 Reagents
Unless otherwise stated, only reagents and laboratory secondary water confirmed to be analytically pure are used in the analysis.
5.1 Hydrogen peroxide (ρ=1.10g/mL).
5.2 Hydrochloric acid (ρ=1.19g/mL).
5.3 Sodium hydroxide solution (200g/L).
5.4 Sodium hydroxide solution (35g/L).
5.5 Potassium thiocyanate solution (500g/L).
5.6 Stannous chloride-titanium trichloride solution. Weigh 10g of tin dichloride and heat and dissolve it in 600mL hydrochloric acid (5.2), and add it after the dissolution is complete
1.25mL of titanium trichloride, diluted with water to 1000mL, mixed well, and stored in a brown bottle. If the purple of titanium trichloride in the solution fades, it should be heavy
Newly prepared.
5.7 Tungsten standard storage solution. weigh 1.2611g of tungsten trioxide that has been burned at 800°C for 40 minutes and cooled to room temperature in a desiccator
(wWO3≥99.99%), put in a 250mL PTFE beaker, add 175mL sodium hydroxide solution (5.3), slightly heat until the dissolution is complete
Transfer the whole into a 1000mL volumetric flask, dilute to the mark with water, mix well, and transfer to a plastic bottle for storage. This solution 1mL contains 1mg tungsten.
5.8 Tungsten standard solution. Pipette 10.00mL tungsten standard stock solution (5.7) into a 100mL volumetric flask, dilute with sodium hydroxide solution (5.4)
Release to the mark, mix well, and transfer to a plastic bottle for storage. This solution 1mL contains 100μg tungsten.
6 Instruments
Spectrophotometer.
7 Sample
Process the sample into chips not larger than 1mm.
8 Analysis steps
8.1 Sample
Weigh a sample with a mass (m) of 0.25g (Chapter 7), accurate to 0.0001g.
8.2 Parallel test
Do two tests in parallel and take the average value.
8.3 Blank test
Do a blank test with the sample (8.1).
8.4 Determination
8.4.1 Place the sample (8.1) in a 300mL polytetrafluoroethylene beaker, add a total of 20mL sodium hydroxide solution (5.3) in batches, and wait.
After the violent reaction ceases, wash the wall of the cup with a small amount of water, place it on a hot plate and evaporate to dryness at low temperature and cool. Add 3mL hydrogen peroxide dropwise while shaking
(5.1). Add 70mL of water, place it on a hot plate to heat to dissolve the salt, keep it boiling for 30min, add water and keep the volume about 70mL, take
Down and cool down. Transfer to a 100mL volumetric flask (V0), dilute to the mark with water, and mix.
8.4.2 Use quick filter paper to filter the test solution in the original polytetrafluoroethylene beaker, discard the first 15mL~20mL filtrate, and pipette according to Table 1.
Separate the filtrate (V1) in a 50mL volumetric flask, add a corresponding volume of sodium hydroxide solution (5.4), add 2mL potassium thiocyanate solution (5.5),
Mix well, add stannous chloride-titanium trichloride solution (5.6) to close to the mark, mix well, cool, and then dilute with stannous chloride-titanium trichloride solution (5.6)
To the mark, mix well. Leave it for 15 minutes.
8.4.3 Move the solution (8.4.2) into a 1cm cuvette, take the blank test solution as a reference, and measure it at the wavelength of 404nm with a spectrophotometer
Absorbance, find the corresponding tungsten mass (m1) from the working curve.
8.5 Drawing of working curve
8.5.1 Pipette 0mL, 0.50mL, 1.00mL, 2.00mL, 5.00mL, 7.00mL tungsten standard solution (5.8) into a set of 50mL volume
In the bottle, add sodium hydroxide solution (5.4) to 20mL. The following shall proceed according to 8.4.2.
8.5.2 Pipette part of the series of standard solutions into a 1cm cuvette, use the zero-concentration solution of the standard series as a reference, and set it at the wavelength of the spectrophotometer.
Measure the absorbance at 404nm. Use tungsten mass as the abscissa and absorbance as the ordinate to draw the working curve.
9 Test data processing
The tungsten content is calculated as tungsten mass fraction wW, calculated according to formula (1).
The calculation result is expressed to two decimal places. The rounding of values shall be implemented in 3.2 and 3.3 of GB/T 8170-2008.
10 Precision
10.1 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 value of r does not exceed the repeatability limit r, and the repeatability limit r does not exceed 5%. The repeatability limit r is linearly interpolated according to the data in Table 2.
Method or extension method.
10.2 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 value of R does not exceed the reproducibility limit R, and the reproducibility limit R does not exceed 5%. The reproducibility limit R is within the linear range according to the data in Table 3.
Obtained by interpolation or extension method.
11 Test report
The test report should include the following.
a) Number and name of this part;
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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