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

ISO 17925:2004 specifies methods of determining the coating mass per unit area by gravimetry and chemical composition on one side-surface of zinc- and/or aluminium-based coatings on steel by means of inductively coupled plasma atomic emission spectrometric or flame atomic absorption spectrometry. This method is applicable to zinc contents between 40 % (mass fraction) and 100 % (mass fraction); aluminium contents between 0,02 % (mass fraction) and 60 % (mass fraction); nickel contents between 7 % (mass fraction) and 20 % (mass fraction); iron contents between 0,2 % (mass fraction) and 20 % (mass fraction); silicon contents between 0,2 % (mass fraction) and 10 % (mass fraction); lead contents between 0,005 % (mass fraction) and 2 % (mass fraction). These test methods are intended as referee methods to test such materials for compliance with mass per unit area and compositional specifications of International Standards.

Revêtements à base de zinc et/ou d'aluminium sur acier -- Détermination de la masse surfacique et de la composition chimique du revêtement -- Gravimétrie, spectrométrie d'émission atomique avec plasma induit par haute fréquence et spectrométrie d'absorption atomique dans la flamme

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Published
Publication Date
28-Oct-2004
Current Stage
6060 - International Standard published
Start Date
22-Sep-2004
Completion Date
29-Oct-2004
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INTERNATIONAL ISO
STANDARD 17925
First edition
2004-11-01
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
Revêtements à base de zinc et/ou d'aluminium sur acier —
Détermination de la masse surfacique et de la composition chimique du
revêtement — Gravimétrie, spectrométrie d'émission atomique avec
plasma induit par haute fréquence et spectrométrie d'absorption
atomique dans la flamme
Reference number
ISO 17925:2004(E)
ISO 2004
---------------------- Page: 1 ----------------------
ISO 17925:2004(E)
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ii © ISO 2004 – All rights reserved
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ISO 17925:2004(E)
Contents Page

Foreword............................................................................................................................................................ iv

1 Scope...................................................................................................................................................... 1

2 Normative references ........................................................................................................................... 1

3 Principle ................................................................................................................................................. 2

4 Reagents ................................................................................................................................................ 2

5 Apparatus............................................................................................................................................... 5

5.1 General................................................................................................................................................... 5

5.2 Inductively coupled plasma atomic emission spectrometer (ICP-AES).......................................... 5

5.3 Flame atomic absorption spectrometer (FAAS) ................................................................................ 6

5.4 Platinum crucible .................................................................................................................................. 7

6 Sampling and samples ......................................................................................................................... 7

7 Determination procedure ..................................................................................................................... 7

7.1 Sample preparation............................................................................................................................... 7

7.2 Determination procedure for mass per unit area .............................................................................. 7

7.3 Procedure of determination of chemical composition by inductively coupled plasma

atomic emission spectrometric method............................................................................................. 8

7.4 Procedure of determination of chemical composition by flame atomic absorption method

— zinc, aluminium, nickel and iron contents................................................................................... 14

8 Expression of results.......................................................................................................................... 14

8.1 Expression of result in mass per unit area ......................................................................................14

8.2 Expression of result of chemical compositions .............................................................................. 15

9 Test report............................................................................................................................................ 17

Annex A (informative) Analyte content .......................................................................................................... 18

Annex B (informative) Additional information on the international cooperative tests.............................. 19

Annex C (informative) Graphical representation of precision data............................................................. 22

© ISO 2004 – All rights reserved iii
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ISO 17925:2004(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies

(ISO member bodies). The work of preparing International Standards is normally carried out through ISO

technical committees. Each member body interested in a subject for which a technical committee has been

established has the right to be represented on that committee. International organizations, governmental and

non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the

International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 17925 was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 1, Methods of

determination of chemical composition.
iv © ISO 2004 – All rights reserved
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INTERNATIONAL STANDARD ISO 17925:2004(E)
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
1 Scope

This International Standard specifies methods of determining the coating mass per unit area by gravimetry

and chemical composition on one side-surface of zinc- and/or aluminium-based coatings on steel by means of

inductively coupled plasma atomic emission spectrometric or flame atomic absorption spectrometry. For

example, this test method applies for zinc and/or aluminium based coatings on steel such as galvanize (hot

dip and electrolytic), galvaneal (hot-dip), zinc-nickel electrolytic, zinc-5 % aluminium coating (hot-dip) and zinc-

55 % aluminium coating (hot-dip). Galvanizing gives a pure zinc coating. Galvanealling gives a zinc-iron

alloyed coating. Zinc-nickel electrolytic methods give zinc-nickel alloyed coatings.

This method is applicable to zinc contents between 40 % (mass fraction) and 100 % (mass fraction);

aluminium contents between 0,02 % (mass fraction) and 60 % (mass fraction); nickel contents between 7 %

(mass fraction) and 20 % (mass fraction); iron contents between 0,2 % (mass fraction) and 20 % (mass

fraction); silicon contents between 0,2 % (mass fraction) and 10 % (mass fraction); lead contents between

0,005 % (mass fraction) and 2 % (mass fraction). For example, the applicable elements for these products are

as follows: galvanizing is specified for iron and aluminium; galvanealling is specified for zinc, iron and

aluminium; zinc-nickel electrolytic methods are specified for zinc, iron and nickel; zinc-5 % aluminium coating

is specified for zinc, iron, aluminium and silicon; zinc-55 % aluminium is specified for zinc, iron, aluminium and

silicon.

FAAS determination for the chemical composition of a coating layer is not applicable for zinc.

These test methods are intended as referee methods to test such materials for compliance with mass per unit

area and compositional specifications of International Standards.
2 Normative references

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.
ISO 648:1977, Laboratory glassware — One-mark pipettes
ISO 1042:1998, Laboratory glassware — One-mark volumetric flasks

ISO 3696:1987, Water for analytical laboratory use — Specification and test methods

ISO 5725-1:1994, Accuracy (trueness and precision) of measurement methods and results — Part 1: General

principles and definitions

ISO 5725-2:1994, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic

method for the determination of repeatability and reproducibility of a standard measurement method

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ISO 17925:2004(E)

ISO 5725-3:1994, Accuracy (trueness and precision) of measurement methods and results — Part 3:

Intermediate measures of the precision of a standard measurement method

ISO 14284:1996, Steel and iron — Sampling and preparation of samples for the determination of chemical

composition
3 Principle

Stripping the coating on one side on the base steel in a mixture of hydrochloric acid solution containing an

inhibitor to prevent the attack on the base steel. Determination of the mass per unit area of coating from the

mass difference of the specimen before and after stripping. Calculating the coating mass as the mass

difference divided by the specimen's surface area.

Dilution of the stripped solution of the coating on one side. Filtration and nebulization of the solution into an

inductively coupled plasma atomic emission spectrometer (ICP-AES) or flame atomic absorption spectrometer

(FAAS). Calculating the chemical compositions of coating layer as the content of the analytical element

divided by the pre-measured coating mass.
Examples of the analytical lines are given in Table 1.
Table 1 — Examples of analytical lines together with interfering elements
ICP-AES FAAS
Analytical line Analytical line
Element
Interfering Interfering
elements elements
nm nm
481,0
Zinc
206,19
309,3
Aluminium 396,15
306,16
232,00
Nickel 231,60 231,10
233,75
271,44 248,33
Iron
259,94 252,29
251,61 251,61
Silicon Aluminium Aluminium
288,16 288,16
Zinc 217,00
Lead 220,35
Aluminium 283,31
4 Reagents

During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only

grade 2 water as specified in ISO 3696.
4.1 Hydrochloric acid, HCl, ρ ≈ 1,18 g/ml.
4.2 Hydrochloric acid, HCl, diluted 1+10.
4.3 Nitric acid, HNO , ρ ≈ 1,40 g/lml.
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ISO 17925:2004(E)
4.4 Nitric acid, HNO , diluted 1+1.

4.5 Mixed acid, prepared by adding 50 ml of nitric acid (4.3) and 10 ml of hydrochloric acid (4.1) to a flask

containing 150 ml of water and mixing.
4.6 Sodium carbonate, Na CO .
2 3

4.7 Hexamethylenetetramine, C H N , capable of preventing acid attack of the base metal while

6 12 4
stripping the coating from the base steel.

4.8 Stripping solution, prepared by transferring from 170 ml to 500 ml of hydrochloric acid (4.1) to a 1 l

graduated cylinder containing from 450 ml to 820 ml of water and adding 3,5 g of hexamethylenetetramine

(4.7) then diluting to the mark with water followed by mixing.

NOTE For an electrolytic zinc coated steel such as one with a lower coating mass, it would be better to use diluted

hydrochloric acid for stripping in order to prevent the dissolution of base steel.

4.9 Stop-off materials, capable of protecting one side of a coated piece of steel sheet while the other side

is being stripped in hydrochloric acid solution, without contaminating the acid solution and either gaining or

losing mass thus avoiding interference with coating mass and chemical composition determination.

NOTE 1 Acid-resistant paints, lacquers or acid-resistant tapes are commonly used as stop-off materials.

NOTE 2 For this purpose mechanical devices may also be used, fastened to the test specimen instead of the above

materials.
4.10 Zinc stock standard solution, 1 000 mg/l, prepared as follows:

weigh, to the nearest 0,000 5 g, 0,5 g of high purity zinc (minimum 99,99 % by mass) and dissolve in 25 ml

hydrochloric acid (4.1). Cool and transfer the solution quantitatively to a calibrated 500 ml one-mark volumetric

flask. Keep the flask at the same temperature as that at which the flask was calibrated. Dilute to the mark with

water and mix.
4.11 Zinc standard solution A, 100 mg/l, prepared as follows:

using a calibrated pipette, transfer 100 ml of the zinc stock standard solution (4.10) into a calibrated 1 000 ml

one-mark volumetric flask. Add 10 ml of hydrochloric acid (4.1). Dilute to the mark with water and mix.

4.12 Zinc standard solution B, 10 mg/l, prepared as follows:

using a calibrated pipette, transfer 100 ml of the zinc standard solution A (4.11) into a calibrated 1 000 ml one-

mark volumetric flask. Add 10 ml of hydrochloric acid (4.1). Dilute to the mark with water and mix.

4.13 Zinc standard solution for matrix matching, 10 000 mg/l, prepared as follows:

weigh, to the nearest 0,01 g, 10 g of high purity zinc (minimum 99,99 % by mass) and dissolve in 200 ml

hydrochloric acid (4.1), Cool and transfer the solution quantitatively to a calibrated 1 000 ml one-mark

volumetric flask. Keep the flask at the same temperature as that at which the flask was calibrated. Dilute to the

mark with water and mix.
4.14 Aluminium stock standard solution, 1 000 mg/l, prepared as follows:

weigh, to the nearest 0,000 5 g, 0,5 g of high purity aluminium (minimum 99,95 % by mass) and dissolve in a

mixture of 25 ml hydrochloric acid (4.1) and 5 ml nitric acid (4.3). Cool and transfer the solution quantitatively

to a calibrated 500 ml one-mark volumetric flask. Keep the flask at the same temperature as that at which the

flask was calibrated. Dilute to the mark with water and mix.
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ISO 17925:2004(E)
4.15 Aluminium standard solution A, 100 mg/l, prepared as follows:

using a calibrated pipette, transfer 100 ml of the aluminium stock standard solution (4.14) into a calibrated

1 000 ml one-mark volumetric flask. Add 10 ml of hydrochloric acid (4.1). Dilute to the mark with water and mix.

4.16 Aluminium standard solution B, 10 mg/l, prepared as follows:

using a calibrated pipette, transfer 100 ml of the aluminium standard solution A (4.15) into a calibrated

1 000 ml one-mark volumetric flask. Add 10 ml of hydrochloric acid (4.1). Dilute to the mark with water and mix.

4.17 Aluminium standard solution for matrix matching, 10 000 mg/l, prepared as follows:

weigh, to the nearest 0,01 g, 10 g of high purity aluminium (minimum 99,99 % by mass) and dissolve in a

mixture of 200 ml hydrochloric acid (4.1) and 5 ml nitric acid (4.3). Cool and transfer the solution quantitatively

to a calibrated 1 000 ml one-mark volumetric flask. Keep the flask at the same temperature as that at which

the flask was calibrated. Dilute to the mark with water and mix.
4.18 Nickel stock standard solution, 1 000 mg/l, prepared as follows:

weigh, to the nearest 0,000 5 g, 0,5 g of high purity nickel (minimum 99,95 % by mass) and dissolve in 30 ml

nitric acid (1+1) (4.4). Cool and transfer the solution quantitatively to a calibrated 500 ml one-mark volumetric

flask. Keep the flask at the same temperature as that at which the flask was calibrated. Dilute to the mark with

water and mix.
4.19 Nickel standard solution A, 100 mg/l, prepared as follows:

using a calibrated pipette, transfer 100 ml of the nickel stock standard solution (4.18) into a calibrated

1 000 ml one-mark volumetric flask. Add 10 ml of hydrochloric acid (4.1). Dilute to the mark with water and mix.

4.20 Nickel standard solution B, 10 mg/l, prepared as follows:

using a calibrated pipette, transfer 100 ml of the nickel standard solution A (4.19) into a calibrated 1 000 ml

one-mark volumetric flask. Add 10 ml of hydrochloric acid (4.1). Dilute to the mark with water and mix.

4.21 Iron stock standard solution, 1 000 mg/l, prepared as follows:

weigh, to the nearest 0,000 5 g, 0,5 g of high purity iron (minimum 99,95 % by mass) and dissolve in 25 ml

hydrochloric acid (4.1). Cool and transfer the solution quantitatively to a calibrated 500 ml one-mark volumetric

flask. Keep the flask at the same temperature as that at which the flask was calibrated. Dilute to the mark with

water and mix.
4.22 Iron standard solution A, 100 mg/l, prepared as follows:

using a calibrated pipette, transfer 100 ml of the iron stock standard solution (4.21) into a calibrated 1 000 ml

one-mark volumetric flask. Add 10 ml of hydrochloric acid (4.1). Dilute to the mark with water and mix.

4.23 Iron standard solution B, 10 mg/l, prepared as follows:

using a calibrated pipette, transfer 100 ml of the iron standard solution A (4.22) into a calibrated 1 000 ml one-

mark volumetric flask. Add 10 ml of hydrochloric acid (4.1). Dilute to the mark with water and mix.

4.24 Silicon stock standard solution, 1 000 mg/l, prepared as follows:

weigh, to the nearest 0,000 1 g, 2,139 3 g of freshly calcined high purity silica (minimum 99,9 % by mass

SiO ) and transfer to a platinum crucible. The high-purity silica shall be calcined for 1 h at 1 100°C and cooled

in a desiccator immediately before use. Mix thoroughly with 16 g of anhydrous sodium carbonate and fuse at

1 050°C for 30 min. Extract the fusion product with 100 ml of water in a polypropylene or

polytetrafluoroethylene beaker (see Note below). Cool and transfer the extract, which should contain no trace

of residue, to a 1 000 ml one-mark volumetric flask. Keep the flask at the same temperature as that at which

4 © ISO 2004 – All rights reserved
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ISO 17925:2004(E)

the flask was calibrated. Dilute to the mark and mix, transfer immediately to a well-stoppered

polytetrafluoroethylene bottle for storage. 1 ml of this stock solution contains 1 mg of silicon.

NOTE Extraction of the fusion product may require prolonged digestion in water followed by gentle heating.

4.25 Silicon standard solution A, 100 mg/l, prepared as follows:

using a calibrated pipette, transfer 100 ml of the silicon stock standard solution (4.24) into a calibrated

1 000 ml one-mark volumetric flask. Dilute to the mark with water and mix.
4.26 Silicon standard solution B, 10 mg/l, prepared as follows:

using a calibrated pipette, transfer 100 ml of the silicon standard solution A (4.25) into a calibrated 1 000 ml

one-mark volumetric flask. Dilute to the mark with water and mix.
4.27 Lead stock standard solution, 1 000 mg/l, prepared as follows:

weigh, to the nearest 0,000 5 g, 0,5 g of high purity lead (min 99,95 % by mass) and dissolve in 30 ml nitric

acid (1+1) (4.3). Cool and transfer the solution quantitatively to a calibrated 500 ml one-mark volumetric flask.

Keep the flask at the same temperature as that at which the flask was calibrated. Dilute to the mark with water

and mix.
4.28 Lead standard solution A, 100 mg/l, prepared as follows:

using a calibrated pipette, transfer 100 ml of the lead stock standard solution (4.27) into a calibrated 1 000 ml

one-mark volumetric flask. Dilute to the mark with water and mix.
4.29 Lead standard solution B, 10 mg/l, prepared as follows:

using a calibrated pipette, transfer 100 ml of the lead stock standard solution (4.28) into a calibrated 1 000 ml

one-mark volumetric flask. Dilute to the mark with water and mix.

4.30 Suitable solvent, appropriate for washing greasy or dirty test samples, e.g., acetone.

5 Apparatus
5.1 General

All volumetric glassware shall be class A and calibrated, in accordance with ISO 648 or ISO 1042 as

appropriate.
Use ordinary laboratory apparatus other than volumetric glassware.
5.2 Inductively coupled plasma atomic emission spectrometer (ICP-AES)
5.2.1 General

The ICP-AES used shall be satisfactory only after optimizing according to the manufacture's instructions.

The spectrometer can be either the simultaneous or the sequential type. If a sequential spectrometer can be

equipped with an extra arrangement for simultaneous measurement of the internal standard line, it can be

used with the internal reference technique. If the sequential spectrometer is not equipped with this

arrangement, an internal reference technique shall not be used.
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ISO 17925:2004(E)
5.2.2 Practical resolution of the spectrometer

Calculate the bandwidth (full width at half maximum) for the analytical line used including the line for internal

reference. The bandwidth shall be less than 0,030 nm.
5.2.3 Short-term stability

Calculate the standard deviation of ten measurements of the absolute intensity or intensity ratio of the emitted

light of the most concentrated calibration solution for analyte. The relative standard deviation shall not exceed

0,4 %.
5.2.4 Background equivalent concentration and detection limit

Calculate the background equivalent concentration (BEC) and detection limit (DL), for the analytical line in a

solution containing only the analyte element. The values of BEC and DL shall be below the value listed in

Table 2.

Table 2 — Background equivalent concentration, detection limit and characteristic mass

Inductively coupled atomic emission spectrometry
Background equivalent Detection limit
Element
concentration
mg/l mg/l
Zinc 1,0 0,4
Aluminium 6,0 0,2
Iron 2,0 0,1
Silicon 3,0 0,1
Lead 2,5 0,1
5.3 Flame atomic absorption spectrometer (FAAS)
5.3.1 General

The FAAS used will be satisfactory only after optimizing according to the manufacturer's instructions.

5.3.2 Short-term stability

The standard deviation of ten measurements of the absorbance of the most concentrated calibration solution

shall not exceed 1,5 % of the mean absorbance of the same solution.

The standard deviation of ten measurements of the absorbance of the least concentrated calibration solution

shall not exceed 0,5 % of the mean absorbance of the same solution.
5.3.3 Detection limit

Calculate the detection limit (DL) for the analytical line in a solution containing only the analyte element. This

is defined as three times the standard deviation of ten measurements of the absorbance of a solution

containing the appropriate element at a concentration level selected to give an absorbance just above that of

the zero member.
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ISO 17925:2004(E)
5.3.4 Calibration graph linearity

The slope of the calibration graph covering the top 20 % of concentration range (expressed as a change in

absorbance) shall not be less than 0,7 times the value of the slope for the bottom 20 % of the concentration

range determined in the same way. For instruments with automatic calibration using two or more standards, it

shall be established prior to the analysis, by obtaining absorbance readings, that the above requirements for

graph linearity are fulfilled.
5.3.5 Characteristics concentration

Calculate the characteristics concentration for the analyte in a matrix similar to the final test solution.

5.4 Platinum crucible
6 Sampling and samples

Sampling of test specimens for determining mass per unit area and chemical compositions of coating shall be

carried out in accordance with ISO 14284 and products standards, if specified. Test specimens shall be of

2 2

square, rectangular or round shape with a surface area of preferably 1 900 mm to 3 500 mm . In case of

dispute, test specimens shall be squares with sides of 50 mm ± 5 mm. One test specimen is required for each

side to be determined.
7 Determination procedure
7.1 Sample preparation

Clean the specimens with suitable solvent (4.30) using a soft paper towel, then dry with oil-free compressed

air.

Cover the side of the specimen from which the coating is not to be stripped with stop-off materials (4.9).

Use a roller, in the case of tape, to press the tape firmly against the sheet, making sure to remove all air

bubbles or wrinkles. Trim off the excess tape.
Preferably protect the edges with stop-off materials (4.9).
7.2 Determination procedure for mass per unit area

Using a calliper traceable to national or International Standards, measure the size of sample to be stripped to

the nearest 0,05 mm and calculate the area of the sample to the nearest 0,1 mm .

The area of the square test specimens shall be calculated as (a + b) × d/2 when the test specimen is not really

square and where d is the length of a diagonal line, and a and b are lengths of vertical lines from the corners

to the diagonal line (see Figure 1). Dimensions a, b and d shall be measured to the nearest 0,05 mm using a

device traceable to national or International Standards.

When the test specimen is not really square, if all corner angles are within a 4° deviation from 90°, the area of

the square and rectangle test specimens may be calculated as [(A + B) × (C + D)]/4, where A and B, C and D

are lengths of opposite sides as shown in Figure 1.
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ISO 17925:2004(E)
Figure 1 — Dimensions of square test specimens

Using a balance traceable to national or International Standards, weigh the prepared specimen to the nearest

0,1 mg and record the weight as the original weight of the specimen.

Place the sample in a sufficiently large beaker, e.g., 600 ml, with the protected coating side down.

Slowly add 30 ml of stripping solution (4.8) (see Note 2) at room temperature and leave until the coating has

completely dissolved. The end of the dissolution process can be recognized by the cessation of the initially

brisk evolution of hydrogen.

NOTE 1 The stripping time will depend on the chemical composition of the coating, its mass per unit area and the room

temperature. Dilution of the stripping solution (4.8) may be acceptable in order to prolong the stripping time for thinner

coatings.

NOTE 2 In the process of dissolving the coating layer, determination of the end point should be confirmed with the

intent of optimizing the stripping time and hydrochloric acid concentration for each type of sample.

After the coating is stripped, remove the sample by an appropriate method. Holding it over the same beaker,

rinse it carefully with water, and brush the stripped side to remove any loose substance which may be

adhering to the surface and, if necessary, dip in alcohol.

Dry the stripped specimen with oil-free compressed air and weigh it to the nearest 0,1 mg using a balance

traceable to national or International Standards.
Reserve this sample solution for the determination of chemical composition.

7.3 Procedure of determination of chemical composition by inductively coupled plasma

atomic emission spectrometric method

7.3.1 Test solution for determination of zinc, aluminium, nickel, iron and lead contents

Use the sample solution reserved in 7.2 as test solution. If some undissolved substance remains in the

solution, warm the beaker on a hot plate until all the stripped coating is dissolved. Transfer the solution to a

100 ml volumetric flask, dilute to the mark and mix thoroughly.

If the analyte content in the test solution is estimated to be greater 25 mg (see Table 3) or is too high to apply

calibration series given in 7.3.5, pipette 10 ml of the sample solution into a volumetric flask, dilute to the mark

and mix.

Record the dilution factor, D, as the volume of a volumetric flask divided by 10 ml.

7.3.2 Test solution for determination of zinc, aluminium, nickel, iron, lead and silicon contents

Use the sample solution reserved in 7.2 as test solution. If some undissolved substance remains in the

solution, warm the beaker on a hot plate until all the stripped coating is dissolved.

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ISO 17925:2004(E)
Filter the sample solution thr
...

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