GB/T 24514-2009Zinc 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 (English PDF)

Foreword

This Standard modified and adopted ISO 17925.2004 "Zinc and/or aluminium based

coatings on steel - Determination of coating mass per unit area and chemical

composition - Gravimetry, inductively coupled plasma atomic emission spectrometry

and flame atomic absorption spectrometry" (English version).

For ease of use, the following modifications were made to this Standard.

- Deleted the foreword of ISO 17925.2004;

- Made structural and editorial changes to the "Scope" of ISO 17925.2004.Deleted

all references to lead content determination in "Scope" and the corresponding

sections that follow;

- Changed the normative references according to the corresponding Chinese national

standards. Sorted by national standard number in Chapter 2;

- Edited the notes in 4.8, 4.9 and 7.2 of ISO 17925.2004 into the text of this Standard;

- Modified article 5.2.3 of ISO 17925.2004 that "the relative standard deviation shall

not be greater than 0.4%" to "the relative standard deviation shall not be greater than

1.0%" in this Standard, according to the accuracy level of ICP instruments,

metrological verification regulations and actual use requirements;

- Corrected "0.5% of the mean absorbance of the lowest calibration solution" in

article 5.3.2 of ISO 17925.2004 to "0.5% of the average absorbance of the highest

calibration solution" in this Standard;

- Made structural editorial changes to articles 7.3 and 7.4 of ISO 17925.2004;

- Corrected the editorial error "C-1 to C-4" in articles 7.3.5.1 and 7.3.6.1 of ISO

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.

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)

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.

4 Reagents and materials

Unless otherwise specified, only the reagents confirmed as analytically pure, and the

grade two water specified in GB/T 6682 are used in the analysis.

5 Apparatus

The ICP-AES used shall be optimized for use in accordance with the manufacturer's

instructions.

Calculate the bandwidth (width at half maximum) of the analytical line and the internal

marker. The bandwidth shall be less than 0.030nm.

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.

7 Determination steps

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

of the perpendiculars from a corner to the diagonal (see Figure 1).

8 Representation of results

The precision test results are statistically processed in accordance with the provisions

of GB/T 6379.1, GB/T 6379.2 and ISO 5725-3.

Calculate the content of the element to be tested in the coating according to formula (2),

expressed in mass fraction (%).

9 Test report

The test report shall include the following.

Annex A

(informative)

Analyte content in the coating

The analyte content in the test solution and the associated coating mass and percentage

of analyte in the coating are listed in Table A.1.In this table, the coating mass of the

sample refers to the coating mass peeled off from a square sample with a side length of

50mm.

Annex B

(informative)

Additional explanation for international cooperative tests

The repeatability and reproducibility data in Tables 9 to 14 are derived from the results

of international analytical tests. This test is a joint test conducted in 1999 by 15

laboratories in 9 countries on 10 steel plate samples.

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