GB/T 40342-2021 English PDF (GB/T40342-2021)

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GB/T 40342-2021: Method for determination of aluminum content in hot dipped zinc-aluminum alloy coating on steel wire
GB/T 40342-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.65
CCS H 12
Method for determination of aluminum content in hot
dipped zinc-aluminum alloy coating on steel wire
ISSUED ON: AUGUST 20, 2021
IMPLEMENTED ON: MARCH 1, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 5
4 Principle... 5
5 Reagents ... 5
6 Analysis steps ... 6
7 Calculation of analysis results ... 8
8 Precision... 8
9 Quality assurance and control ... 9
10 Test report ... 9
Method for determination of aluminum content in hot
dipped zinc-aluminum alloy coating on steel wire
Warning -- The personnel using this document shall have practical experience
in formal laboratory work. This document does not indicate all possible safety
issues. 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 document specifies the principle, reagents, analysis steps, the calculation of
analysis results, the calculation of precision, methods of quality assurance and control,
and contents of test reports of the chemical titration method for determining aluminum
content in hot dipped zinc-aluminum alloy coating on steel wire.
This document is applicable to the determination of aluminum content in hot dipped
zinc-aluminum alloy coating on steel wire. The measurement range of aluminum
content is 2.5%~30%.
2 Normative references
The following documents are essential to the application of this document. For the
dated documents, only the versions with the dates indicated are applicable to this
document; for the undated documents, only the latest version (including all the
amendments) is applicable to this standard.
GB/T 601 Chemical reagent -- Preparations of reference titration solutions
GB/T 1839 Test method for gravimetric determination of the mass per unit area of
galvanized coatings on steel products
GB/T 6682 Water for analytical laboratory use -- Specification and test methods
GB/T 8170 Rules of rounding off for numerical values and expression and
judgement of limiting values
3 Terms and definitions
There are no terms and definitions that need to be defined in this document.
4 Principle
Add an excess of EDTA standard solution to the weakly acidic solution to form
complexes with iron, zinc, copper and other elements. Then, in the presence of acetic
acid, boil all aluminum to form a complex; use xylenol orange as an indicator; and use
lead nitrate standard solution to back-titrate an excess of EDTA. Add fluoride to de-
mask Al-EDTA; release the same amount of EDTA as aluminum; and titrate with lead
nitrate standard titration solution; then, calculate the mass fraction of aluminum.
5 Reagents
Unless otherwise specified, only use approved analytical reagents and above grade 3
distilled water that meets the requirements of GB/T 6682 or water of comparable purity.
5.1 Hydrochloric acid (1+1).
5.2 Ammonia (1+1).
5.3 Anhydrous potassium fluoride (KF, solid).
5.4 Deplating hydrochloric acid corrosion inhibitor: Weigh 7.5g of
hexamethylenetetramine (C6H12N4) and dissolve it in 250 mL of hydrochloric acid (see
5.1); add 250 mL of water; mix well.
5.5 EDTA solution (c=0.05 mol/L): Weigh 20g of EDTA (Na2C10H14N2O8 • 2H2O) into a
500 mL beaker. After adding water to dissolve, transfer to a 1000mL volumetric flask;
dilute to the mark with water; mix well.
5.6 Ammonium acetate solution (w=50%): Weigh 100g of ammonium acetate and
dissolve in 100mL of water; mix well.
5.7 Acetic acid-sodium acetate buffer solution (pH=5.5): Weigh 200g of sodium acetate
(CH3COONa • 3H2O); dissolve in water; and add 9mL of glacial acetic acid; then diluted
with water to 1000mL.
5.8 Lead nitrate standard titration stock solution (c=0.05 mol/L): Weigh 17g of lead
nitrate and dissolve it in 1000 mL of nitric acid solution (1+2000); shake well and set
aside. Calibrate in accordance with the regulations of GB/T 601.
5.9 Lead nitrate standard titration solution (c=0.01 mol/L): dilute the lead nitrate
7 Calculation of analysis results
Calculate the mass fraction of aluminum w Al according to formula (3):
Where:
w Al --- The mass fraction of aluminum;
c --- The actual concentration of lead nitrate standard titration solution (see 5.9), in
moles per liter (mol/L);
V --- The volume of consumed lead nitrate standard titration solution (see 5.9) that
is used for titration of released EDTA, the unit is milliliters (mL);
M Al --- The molar mass of aluminum, 26.98g/mol;
Δm --- The mass of the alloy after deducting the iron brought in when the sample is
dissolved, in grams (g);
25/250 --- Dispensing rate.
The result retains two decimal places and is rounded according to GB/T 8170.
8 Precision
8.1 Repeatability
The results of two independent tests under repeatability conditions shall be within the
average range given below. The absolute difference between these two test results
does not exceed the repeatability limit (r); and the probability of exceeding the
repeatability limit (r) is not more than 5%.
Calculate the repeatability limit (r) according to formula (4):
Where:
X --- The average of the two analysis results.
GB/T 40342-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.65
CCS H 12
Method for determination of aluminum content in hot
dipped zinc-aluminum alloy coating on steel wire
ISSUED ON: AUGUST 20, 2021
IMPLEMENTED ON: MARCH 1, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 5
4 Principle... 5
5 Reagents ... 5
6 Analysis steps ... 6
7 Calculation of analysis results ... 8
8 Precision... 8
9 Quality assurance and control ... 9
10 Test report ... 9
Method for determination of aluminum content in hot
dipped zinc-aluminum alloy coating on steel wire
Warning -- The personnel using this document shall have practical experience
in formal laboratory work. This document does not indicate all possible safety
issues. 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 document specifies the principle, reagents, analysis steps, the calculation of
analysis results, the calculation of precision, methods of quality assurance and control,
and contents of test reports of the chemical titration method for determining aluminum
content in hot dipped zinc-aluminum alloy coating on steel wire.
This document is applicable to the determination of aluminum content in hot dipped
zinc-aluminum alloy coating on steel wire. The measurement range of aluminum
content is 2.5%~30%.
2 Normative references
The following documents are essential to the application of this document. For the
dated documents, only the versions with the dates indicated are applicable to this
document; for the undated documents, only the latest version (including all the
amendments) is applicable to this standard.
GB/T 601 Chemical reagent -- Preparations of reference titration solutions
GB/T 1839 Test method for gravimetric determination of the mass per unit area of
galvanized coatings on steel products
GB/T 6682 Water for analytical laboratory use -- Specification and test methods
GB/T 8170 Rules of rounding off for numerical values and expression and
judgement of limiting values
3 Terms and definitions
There are no terms and definitions that need to be defined in this document.
4 Principle
Add an excess of EDTA standard solution to the weakly acidic solution to form
complexes with iron, zinc, copper and other elements. Then, in the presence of acetic
acid, boil all aluminum to form a complex; use xylenol orange as an indicator; and use
lead nitrate standard solution to back-titrate an excess of EDTA. Add fluoride to de-
mask Al-EDTA; release the same amount of EDTA as aluminum; and titrate with lead
nitrate standard titration solution; then, calculate the mass fraction of aluminum.
5 Reagents
Unless otherwise specified, only use approved analytical reagents and above grade 3
distilled water that meets the requirements of GB/T 6682 or water of comparable purity.
5.1 Hydrochloric acid (1+1).
5.2 Ammonia (1+1).
5.3 Anhydrous potassium fluoride (KF, solid).
5.4 Deplating hydrochloric acid corrosion inhibitor: Weigh 7.5g of
hexamethylenetetramine (C6H12N4) and dissolve it in 250 mL of hydrochloric acid (see
5.1); add 250 mL of water; mix well.
5.5 EDTA solution (c=0.05 mol/L): Weigh 20g of EDTA (Na2C10H14N2O8 • 2H2O) into a
500 mL beaker. After adding water to dissolve, transfer to a 1000mL volumetric flask;
dilute to the mark with water; mix well.
5.6 Ammonium acetate solution (w=50%): Weigh 100g of ammonium acetate and
dissolve in 100mL of water; mix well.
5.7 Acetic acid-sodium acetate buffer solution (pH=5.5): Weigh 200g of sodium acetate
(CH3COONa • 3H2O); dissolve in water; and add 9mL of glacial acetic acid; then diluted
with water to 1000mL.
5.8 Lead nitrate standard titration stock solution (c=0.05 mol/L): Weigh 17g of lead
nitrate and dissolve it in 1000 mL of nitric acid solution (1+2000); shake well and set
aside. Calibrate in accordance with the regulations of GB/T 601.
5.9 Lead nitrate standard titration solution (c=0.01 mol/L): dilute the lead nitrate
7 Calculation of analysis results
Calculate the mass fraction of aluminum w Al according to formula (3):
Where:
w Al --- The mass fraction of aluminum;
c --- The actual concentration of lead nitrate standard titration solution (see 5.9), in
moles per liter (mol/L);
V --- The volume of consumed lead nitrate standard titration solution (see 5.9) that
is used for titration of released EDTA, the unit is milliliters (mL);
M Al --- The molar mass of aluminum, 26.98g/mol;
Δm --- The mass of the alloy after deducting the iron brought in when the sample is
dissolved, in grams (g);
25/250 --- Dispensing rate.
The result retains two decimal places and is rounded according to GB/T 8170.
8 Precision
8.1 Repeatability
The results of two independent tests under repeatability conditions shall be within the
average range given below. The absolute difference between these two test results
does not exceed the repeatability limit (r); and the probability of exceeding the
repeatability limit (r) is not more than 5%.
Calculate the repeatability limit (r) according to formula (4):
Where:
X --- The average of the two analysis results.