ISO 17925:2004
(Main)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
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
General Information
Buy Standard
Standards Content (sample)
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)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2004All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2004 – All rights reserved
---------------------- Page: 2 ----------------------
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---------------------- Page: 3 ----------------------
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
---------------------- Page: 4 ----------------------
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 definitionsISO 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
© ISO 2004 – All rights reserved 1---------------------- Page: 5 ----------------------
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 methodISO 14284:1996, Steel and iron — Sampling and preparation of samples for the determination of chemical
composition3 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.
2 © ISO 2004 – All rights reserved
---------------------- Page: 6 ----------------------
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 4stripping 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.© ISO 2004 – All rights reserved 3
---------------------- Page: 7 ----------------------
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---------------------- Page: 8 ----------------------
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 Apparatus5.1 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.© ISO 2004 – All rights reserved 5
---------------------- Page: 9 ----------------------
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 spectrometryBackground 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 stabilityThe 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.6 © ISO 2004 – All rights reserved
---------------------- Page: 10 ----------------------
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 crucible6 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 2square, 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.© ISO 2004 – All rights reserved 7
---------------------- Page: 11 ----------------------
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 method7.3.1 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.
8 © ISO 2004 – All rights reserved---------------------- Page: 12 ----------------------
ISO 17925:2004(E)
Filter the sample solution thr
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.