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GB/T 24514-2009 PDF in English


GB/T 24514-2009 (GB/T24514-2009, GBT 24514-2009, GBT24514-2009)
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GB/T 24514-2009: PDF in English (GBT 24514-2009)

GB/T 24514-2009
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 25.220.40
H 11
Zinc and/or aluminium based coating on steel -
Determination of coating mass per unit area and chemical
composition - Gravimetry, inductively coupled plasma
atomic emission spectrometry and flame atomic absorption
spectrometry
(ISO 17925:2004, MOD)
ISSUED ON: OCTOBER 30, 2009
IMPLEMENTED ON: MAY 01, 2010
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative references ... 5 
3 Principle ... 6 
4 Reagents and materials ... 7 
5 Apparatus ... 10 
5.1 General ... 10 
5.2 Inductively coupled plasma atomic emission spectrometer (APE-APE) ... 10 
5.3 Flame atomic absorption spectrometer (FAA) ... 11 
5.4 Platinum crucible ... 12 
6 Sampling and specimen ... 12 
7 Determination steps ... 12 
7.1 Specimen preparation ... 12 
7.2 Procedure for the determination of mass per unit area ... 12 
7.3 Steps of determination of chemical composition by inductively coupled plasma atomic
emission spectrometry ... 14 
7.4 Steps of determination of chemical composition by flame atomic absorption
spectrometry ... 17 
8 Representation of results ... 20 
8.1 Representation of mass per unit area results ... 20 
8.2 Representation of chemical composition results ... 21 
9 Test report ... 24 
Annex A (informative) Analyte content in the coating ... 24 
Annex B (informative) Additional explanation for international cooperative tests ... 26 
Annex C (informative) Graphical representation of precision data ... 29 
Annex D (informative) Comparison on chapter numbers and titles between this
Standard and the international standard ISO 17925:2004 ... 34 
Zinc and/or aluminium based coating on steel -
Determination of coating mass per unit area and chemical
composition - Gravimetry, inductively coupled plasma
atomic emission spectrometry and flame atomic absorption
spectrometry
1 Scope
This document specifies the method of gravimetry method to determine the coating
mass per unit area, as well as the methods of inductively coupled plasma atomic
emission spectrometry and flame atomic absorption spectrometry to determine
chemical composition of zinc-based and/or aluminum-based single-sided coatings on
steel surfaces.
The zinc-based and/or aluminum-based coatings on the steel surface described in this
Standard include hot-dip and electro-pure zinc coating, hot-dip galvanized iron alloy
coating, electro-galvanized nickel alloy coating, hot-dip galvanized aluminum coating
(5% of aluminum) and hot-dip galvanized aluminum coating (55% of aluminum). The
chemical composition of zinc-based and/or aluminum-based coatings on steels
described in this Standard includes the chemical composition of iron, aluminum in hot-
dip galvanized coatings, zinc, iron and aluminum in alloyed coatings, zinc, iron, nickel
in electro-galvanized nickel coating, hot-dip galvanized aluminum coating (5% of
aluminum), and zinc, iron, aluminium and silicon in hot-dip Al-Zn coating (55% of Al).
The applicable measurement range of this Standard is 40%~100% for zinc content
(mass fraction), 0.02%~60% for aluminum content (mass fraction), 7%~20% for nickel
content (mass fraction), 0.2%~20% for iron content (mass fraction) and 0.2%~10% for
silicon content (mass fraction).
The method for determining the chemical composition of coatings by flame atomic
absorption spectrometry (FAAS) is not applicable to the determination of zinc content.
The determination method of this Standard can be used as an arbitration method.
2 Normative references
The provisions in following documents become the provisions of this Standard through
reference in this Standard. For dated references, the subsequent amendments (excluding
corrigendum) or revisions do not apply to this Standard, however, parties who reach an
agreement based on this Standard are encouraged to study if the latest versions of these
documents are applicable. For undated references, the latest edition of the referenced
document applies.
GB/T 6379.1, Accuracy (trueness and precision) of measurement methods and
results - Part 1: General principles and definitions (GB/T 6379.1-2004, ISO 5725-
1:1994, IDT)
GB/T 6379.2, Measurement methods and results - Accuracy (trueness and precision)
- Part 2: Determine the standard methods of measurement repeatability and
reproducibility of the basic method (GB/T 6379.2-2004, ISO 5725-2:1994, IDT)
GB/T 6682, Water for analytical laboratory use - Specification and test methods
(GB/T 6682-2008, ISO 3696:1987, MOD)
GB/T 12806, Laboratory glassware - One-mark volumetric flasks (GB/T 12806-
1991, neq ISO 1042:1983)
GB/T 12808, Laboratory glassware - One mark pipettes (GB/T 12808-1991, neq
ISO 648:1977)
GB/T 20066, Steel and iron - Sampling and preparation of samples for the
determination of chemical composition (GB/T 20066-2006, ISO 14284:1996, IDT)
ISO 5725-3, Accuracy (trueness and precision) of measurement methods and results
- Part 3: Intermediate measures of the precision of a standard measurement method
3 Principle
Use a hydrochloric acid solution containing a corrosion inhibitor to peel off the coating
on one side of the steel surface (the role of the corrosion inhibitor is to prevent
hydrochloric acid from corroding the steel substrate). Respectively determine the mass
of the specimen before and after peeling of the coating. Divide the mass difference by
the surface area of the specimen to obtain the coating mass per unit area.
Remove the coating on the measurement surface of the specimen with a stripping
solution. Dilute, filter and set constant volume the solution. Use an inductively coupled
plasma atomic emission spectrometer (ICP-AES) or a flame atomic absorption
spectrometer (FAAS) to determine. Divide the content of the element to be measured
by the mass of the coating measured in advance to obtain the chemical composition of
the element in the coating.
Table 1 lists the analytical lines and interfering elements for each element. Other
analytical lines can also be selected according to the performance of the spectrometer
used in the laboratory.
stripping solution (4.8), stop-off material protects the non-measured surface coating. It
does not contaminate the acid solution. At the same time, the mass is not increased or
decreased, so as to avoid the influence on the mass of the coating and the determination
of the chemical composition.
Usually acid-resistant paint, paint or acid-resistant tape is used as stop-off material. It
is also possible to use a mechanical device to fasten the specimen to achieve one-sided
closure.
4.10 Zinc standard stock solution: 1000mg/L
Weigh 0.500g of high-purity zinc (mass fraction is not less than 99.99%), accurate to
0.0005g. Dissolve it in 25mL of hydrochloric acid (4.1). After cooling, transfer the
solution to a 500mL volumetric flask. Use water to dilute to the scale. Mix well.
4.11 Zinc standard solution A: 100mg/L
Pipette 100mL of zinc standard stock solution (4.10) into a 1000mL volumetric flask.
Add 10mL of hydrochloric acid (4.1). Use water to dilute to the scale. Mix well.
4.12 Zinc standard solution B: 10mg/L
Pipette 100mL of zinc standard solution A (4.11) into a 1000mL volumetric flask. Add
10mL of hydrochloric acid (4.1). Use water to dilute to the scale. Mix well.
4.13 Zinc standard solution for matrix matching: 10000mg/L
Weigh 10.0g of high-purity zinc (mass fraction not less than 99.99%), accurate to 0.01g.
Dissolve in 200mL of hydrochloric acid (4.1). After cooling, transfer the solution to a
1000mL volumetric flask. Use water to dilute to the scale. Mix well.
4.14 Aluminum standard stock solution: 1000mg/L
Weigh 0.500g of high-purity aluminum (mass fraction is not less than 99.95%), accurate
to 0.0005g. Dissolve in the mixed acid of 25mL of hydrochloric acid (4.1) and 5mL of
nitric acid (4.3). After cooling, transfer the solution to a 500mL volumetric flask. Use
water to dilute to the scale. Mix well.
4.15 Aluminum standard solution A: 100mg/L
Pipette 100mL of aluminum standard stock solution (4.14) into a 1000mL volumetric
flask. Add 10mL of hydrochloric acid (4.1). Use water to dilute to the scale. Mix well.
4.16 Aluminum standard solution B: 10mg/L
Pipette 100mL of aluminum standard solution A (4.15) into a 1000mL volumetric flask.
Add 10mL of hydrochloric acid (4.1). Use water to dilute to the scale. Mix well.
4.17 Aluminum standard solution for matrix matching, 10000mg/L
Weigh 10.0g of high-purity aluminum (mass fraction is not less than 99.99%), accurate
to 0.01g. Dissolve in a mixed acid of 200mL of hydrochloric acid (4.1) and 5mL of
nitric acid (4.3). After cooling, transfer the solution to a 1000mL volumetric flask. Use
water to dilute to the scale. Mix well.
4.18 Nickel standard stock solution: 1000mg/L
Weigh 0.500g of high-purity nickel (mass fraction is not less than 99.95%), accurate to
0.0005g. Dissolve in 30mL of (1+1) nitric acid (4.4). After cooling, transfer the solution
to a 500mL volumetric flask. Use water to dilute to the scale. Mix well.
4.19 Nickel standard solution A: 100mg/L
Pipette 100mL of nickel standard stock solution (4.18) into a 1000mL volumetric flask.
Add 10mL of hydrochloric acid (4.1). Use water to dilute to the scale. Mix well.
4.20 Nickel standard solution B: 10mg/L
Pipette 100mL of nickel standard solution A (4.19) into a 1000mL volumetric flask.
Add 10mL of hydrochloric acid (4.1). Use water to dilute to the scale. Mix well.
4.21 Iron standard stock solution: 1000mg/L
Weigh 0.500g of high-purity iron (mass fraction not less than 99.95%), accurate to
0.0005g. Dissolve in 25mL of hydrochloric acid (4.1). After cooling, transfer the
solution to a 500mL volumetric flask. Use water to dilute to the scale. Mix well.
4.22 Iron standard solution A: 100mg/L
Pipette 100mL of iron standard stock solution (4.21) into a 1000mL volumetric flask.
Add 10mL of hydrochloric acid (4.1). Use water to dilute to the scale. Mix well.
4.23 Iron standard solution B: 10mg/L
Pipette 100mL of iron standard solution A (4.22) into a 1000mL volumetric flask. Add
10mL of hydrochloric acid (4.1). Use water to dilute to the scale. Mix well.
4.24 Silicon standard stock solution: 1000mg/L
Burn the high-purity silicon (SiO2 mass fraction is not less than 99.9%) at 1100°C for
1h. Immediately cool in a desiccator. Weigh 2.1393g of high-purity silicon, accurate to
0.0001g. Place in a platinum crucible. Mix the high-purity silicon with 16g of
anhydrous sodium carbonate and melt at 1050°C for 30min. In a polypropylene or a
Teflon beaker, use 100mL of water to leach out the melt (the melt can be dissolved by
heating slowly in water as needed). Cool and transfer the leaching solution (shall be
free of residues) to a 1000mL volumetric flask. Use water to dilute to the scale. Mix
well. Immediately transfer to a Teflon airtight container for storage.
instruments automatically calibrated with 2 or more standard solutions, a linear
calibration curve meeting the above requirements shall be established from the
absorbance readings obtained prior to analysis.
5.3.5 Characteristic concentration
The characteristic concentration of the analytical element shall be calculated using a
solution that is consistent with the matrix of the final test material solution.
5.4 Platinum crucible
6 Sampling and specimen
Except for special provisions, the sampling of specimens used to determine the mass of
the coating per unit area and the chemical composition of the coating shall be carried
out in accordance with the provisions of GB/T 20066 and related product standards.
The specimen shall be a square, rectangle or circle with a surface area of
1900mm2~3500mm2. To prevent disputes, the specimen shall be a square with a side
length of 50mm ± 5mm. The length of each side of each specimen is required to be
measured.
7 Determination steps
7.1 Specimen preparation
Clean the surface of the specimen with a soft paper towel that is dipped in a suitable
solvent (4.27). Then blow dry the surface of the specimen with oil-free compressed air
or a blower.
Seal the side of the specimen that is not to be measured with the stop-off material (4.9).
If tape is used as the stop-off material, the tape shall be pressed against the surface of
the specimen. Remove air bubbles or wrinkles. Cut off excess tape.
The edge portion of the specimen is preferably sealed with the stop-off material (4.9).
7.2 Procedure for the determination of mass per unit area
Use a caliper to measure the size of the specimen to the nearest of 0.05mm. Calculate
the specimen area, to the nearest of 0.1mm2.
When the square specimen is not a square, the formula for calculating the area of the
specimen is (a + b) × d/2. Where d is the length of the diagonal; a and b are the lengths
7.3 Steps of determination of chemical composition by inductively coupled plasma
atomic emission spectrometry
7.3.1 Preparation of test solutions for the determination of zinc, aluminum, nickel
and iron content
Use the sample solution retained in 7.2 as the test solution. If undissolved material
remains in the solution, place the beaker on a hot plate and heat until all the peeled
plating is dissolved. Transfer the solution to a 100mL volumetric flask. Use water to
dilute to the scale. Mix well.
If the content of the analyte in the test solution is greater than 25mg (see Table 3) or the
concentration is too high, the calibration curve given in 7.3.5 cannot be used for analysis,
it shall pipette 10mL of test solution and transfer to another volumetric flask. Use water
to dilute to the scale. Mix well.
Record the dilution factor D, which is the value obtained by dividing the volume (mL)
of the volumetric flask by 10mL.
7.3.2 Preparation of test solution for determination of silicon content
Use the sample solution retained in 7.2 as the test solution. If undissolved material
remains in the solution, place the beaker on a hot plate and heat until all the peeled
plating is dissolved.
Use medium speed filter paper to filter the test solution. Wash the filter paper several
times with hydrochloric acid (4.2) and warm water. Transfer all the filtrate into a 100mL
volumetric flask. Use water to dilute to the scale. Mix well (test solution No. 1).
Put the residue together with filter paper into a platinum crucible (5.4). After drying,
ashing is carried out at 800°C, and cooled in air. Add 2g of sodium carbonate (4.6), melt
at 1050°C and then cool to room temperature. Use 50mL of mixed acid (4.5) to dissolve;
transfer to 100mL capacity bottle; use water to dilute to the mark, and mix well (test
solution No. 2).
7.3.3 Optimization of spectrometers
Start ICP-AES. Sufficiently warm-up before analysis to allow the instrument to
stabilize.
According to the requirements of the operation manual, make the instrument reach the
optimal state.
Prepare software for measuring analytical line intensities, mean and relative standard
deviation.
If using the internal standard method, prepare software that calculates the ratio of
analyte intensity to internal standard intensity. The internal standard intensity shall be
measured simultaneously with the analytical line intensity.
ICP-AES checks the performance of the instrument in accordance with the
requirements of 5.2.2 to 5.2.4.
7.3.4 Blank test
7.3.4.1 General
Be in parallel with the determination of each test solution. Use the same procedures and
instruments. Carry out blank test with blank test solution.
7.3.4.2 Preparation of blank test solution
Add 30mL of stripping solution (4.8) to the beaker. Then add an appropriate amount of
zinc standard solution (4.13) and/or aluminum standard solution (4.17) for matrix
matching. Make the concentration of zinc and/or aluminum equivalent to that in the test
solution.
Transfer the solution to a 100mL volumetric flask. Use water to dilute to the scale. Mix
well.
If the test solution needs to be diluted, the blank test solution shall also be diluted with
the same dilution.
7.3.5 Establishment of ICP calibration curve
C-1 to C-3 below list the ICP calibration series. However, each laboratory can create its
own calibration series in combination with series C-1 to C-3.
According to Table 3 to Table 5, pipette the standard stock solution or standard solution
of each analyte into the corresponding 100mL volumetric flask. Add 30mL of stripping
solution (4.8). Then add the appropriate amount of zinc standard solution (4.13) and/or
aluminum standard solution (4.17) for matrix matching. Make the concentration of zinc
and/or aluminum equivalent to that in the test solution. When measuring the silicon
content in test solution No. 2, add the same amount of sodium carbonate (4.6) and mixed
acid (4.5). Use water to dilute to the scale. Mix well.
Table 3 -- ICP calibration series C-1
Take the net intensity as the ordinate, and the concentration of each element to be
measured in the calibration solution (expressed in mg/mL) as the abscissa. Prepare a
calibration curve by linear regression.
7.3.6 Determination of zinc, aluminum, nickel and iron content in test solution
After the calibration curve (7.3.5) is established, first determine the spectral intensity
of each analyte in the calibration solution (Table 3 to Table 5 in 7.3.5). If the spectral
intensity of the calibration solution is not within ±2% of the initial value obtained when
the calibration curve is established, recalibrate the instrument.
Determine the spectral intensity of blank solution (7.3.4) and unknown test solution
(7.3.1). The content (mg/L) of each analytical element in the blank solution and the
unknown test solution is checked on the corresponding calibration curve by its spectral
intensity.
7.3.7 Determination of silicon content in test solution
After the calibration curve (7.3.5) is established, first measure the spectral intensity of
silicon in the calibration solution (Table 3 to Table 5 in 7.3.5). If the spectral intensity
of the calibration solution is not within ±2% of the initial value obtained when the
calibration curve is established, recalibrate the instrument.
Determine the spectral intensity of blank solution (7.3.4), test solution No. 1 and test
solution No. 2 (7.3.2). The silicon content (mg/L) in the blank solution and the unknown
test solution is checked on the corresponding calibration curve by its spectral intensity.
7.4 Steps of determination of chemical composition by flame atomic absorption
spectrometry
7.4.1 Preparation of test solutions for the determination of aluminium, nickel and
iron content
Prepare test solutions for the determination of aluminum, nickel and iron content in
accordance with 7.3.1.
7.4.2 Preparation of test solution for determination of silicon content
Prepare the test solution for the determination of silicon content according to 7.3.2.
7.4.3 Optimization of spectrometers
Start FAAS. Sufficiently warm-up before analysis to allow the instrument to stabilize.
According to the requirements of the operation manual, make the instrument reach the
optimal state.
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.