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GB/T 14849.2-2007 English PDF (GBT14849.2-2007)

GB/T 14849.2-2007 English PDF (GBT14849.2-2007)

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GB/T 14849.2-2007: Methods for chemical analysis of silicon metal -- Part 2: Determination of aluminium content -- Chrome azurol S spectrophotometric method

This Part specifies the method for determination of aluminum content in silicon metal. This Part applies to the determination of aluminum content in silicon metal. Determination range (mass fraction): 0.02%~0.30%.
GB/T 14849.2-2007
GB
ICS 77.120.10
H 12
NATIONAL STANDARD
OF THE PEOPLE REPUBLIC OF CHINA
Replacing GB/T 14849.2-1993
Methods for chemical analysis of silicon metal -
Part 2. Determination of aluminum content -
Chrome azurol S spectrophotometric method
ISSUED ON. OCTOBER 25, 2007
IMPLEMENTED ON. APRIL 1, 2008
Issued by. General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China;
Committee of Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Method summary ... 4
3 Reagents ... 4
4 Instruments ... 5
5 Sample ... 5
6 Analytical steps ... 5
7 Calculation of the analysis results ... 6
8 Precision ... 7
9 Quality assurance and control ... 7
Foreword
GB/T 14849 Methods for Chemical Analysis of Silicon Metal is divided into 4 parts. ?€? Part 1. Determination of iron content - 1, 10-phenanthroline spectrophotometric method;
?€? Part 2. Determination of aluminum content - chrome azurol-S spectrophotometric method;
?€? Part 3. Determination of calcium content - flame atomic absorption spectrometry, chlorophosphonazo I spectrophotometric method;
?€? Part 4. Inductively coupled plasma-atomic emission spectrometry to determine element content.
This is Part 2 of GB/T 14849.
This Part will replace GB/T 14849.2-1993 Silicon metal - Determination of aluminium content--Chrome azurol S spectrophotometric method. Compared with GB/T
14849.2-1993, the main changes are as follows.
?€? ?€?Repeatability?€? and ?€?quality assurance and control?€? is added.
This Part was proposed by China Nonferrous Metals Industry Association. This Part shall be under the jurisdiction of the National Technical Committee on Nonferrous Metals of Standardization.
This Part was responsibly drafted by Fushun Aluminium Co., Ltd.
Main drafters of this Part. Xu Tieling, Ji Chunlei, Yang Yuhong, and Xu Tieling. The previous version of the standard replaced by this Part is as follows. ?€? GB/T 14849.1-1993.
Methods for chemical analysis of silicon metal - Part 2.
Determination of aluminum content - Chrome azurol S
spectrophotometric method
1 Scope
This Part specifies the method for determination of aluminum content in silicon metal. This Part applies to the determination of aluminum content in silicon metal. Determination range (mass fraction). 0.02%~0.30%.
2 Method??summary
The specimen is decomposed with hydrofluoric acid and nitric acid. Sulfuric acid?€?s smoking removes silicon, fluorine, etc. The residue is dissolved with hydrochloric acid. Ascorbic acid is used to mask the interference of ferrum. A purplish-red complex compound is formed by the aluminum and chrome azurol-S, in hexamethylenetetramine medium of pH5.5-6.1. At wavelength of 510nm of the spectrophotometer, MEASURE the absorbance.
3 Reagents
3.1 Hydrofluoric acid (??1.14g/mL).
3.2 Nitric acid (1+1).
3.3 Sulfuric acid (1+1).
3.4 Hydrochloric acid (1+1).
3.5 Ascorbic acid solution (10g/L). Prepare it when use.
3.6 Hexamethylenetetramine solution (300g/L).
3.7 Chrome azurol S acetic acid solution (0.3g/L). WEIGH 0.30g of chrome azurol-S and PUT into a beaker. ADD 25mL of water and 25mL of anhydrous alcohol. After dissolved, ADD 475mL of water. USE anhydrous alcohol to dilute to 1000mL. MIX evenly. 3.8 Aluminum standard storage solution. WEIGH 0.2500g of metal aluminum and PUT into a polyethylene cup. ADD about 20mL of water and 3.0g of sodium hydroxide. After the reaction slows down, HEAT it on the water bath until dissolved completely. USE V0 ?€? The total volume of test solution A, in unit of mL;
V1 ?€? Volume of test solution A transferred, in unit of mL;
V2 ?€? The total volume of test solution B, in unit of mL;
V3 ?€? Volume of test solution B transferred, in unit of mL;
m0 ?€? Mass of the specimen, in unit of g.
8 Precision
8.1 Repeatability
Under the repeatability condition, within the range of average value given as follows, for the determination values obtained from 2 independent test results, the absolute values of these 2 test results shall not exceed repeatability limit (r). The probability of exceeding repeatability limit (r) is no more than 5%. The repeatability limit (r) is obtained by linear interpolation or extrapolation according to the data in Table 2.
Table 2
Mass fraction of aluminum /% Repeatability limit r/%
0.024 0.002
0.078 0.004
0.300 0.017
8.2 Allowable difference
The difference value of analysis results among the laboratories shall not exceed the allowable difference listed in Table 3.
Table 3
Mass fraction of aluminum /% Allowable difference /%
0.020-0.10 0.004
>0.10-0.30 0.040
9 Quality??assurance??and??control
It shall use national standard sample or industry-level standard sample. CHECK the validity of the analytical method standard every 6 months. When the process is out of control, FIND out the reasons. After correcting the error, REPEAT the checking.

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