ASTM B568-98(2021)

Standard Test Method for Measurement of Coating Thickness by X-Ray Spectrometry

SIGNIFICANCE AND USE
5.1 This is a sensitive, noncontact, and nondestructive method for measuring the coating thickness (and in some cases, coating composition) of metallic and some nonmetallic coatings over a range of thicknesses from as little as 0.01 μm to as much as 75 μm depending on the coating and substrate materials. It can be used to measure coating and base combinations that are not readily measured by other techniques.  
5.2 The coating thickness is an important factor in the performance of a coating in service.
SCOPE
1.1 This test method covers the use of X-ray spectrometry to determine thickness of metallic and some nonmetallic coatings.  
1.2 The maximum measurable thickness for a given coating is that thickness beyond which the intensity of the characteristic secondary X radiation from the coating or the substrate is no longer sensitive to small changes in thickness.  
1.3 This test method measures the mass of coating per unit area, which can also be expressed in units of linear thickness provided that the density of the coating is known.  
1.4 Problems of personnel protection against radiation generated in an X-ray tube or emanating from a radioisotope source are not covered by this test method. For information on this important aspect, reference should be made to current documents of the National Committee on Radiation Protection and Measurement, Federal Register, Nuclear Regulatory Commission, National Institute of Standards and Technology (formerly the National Bureau of Standards), and to state and local codes if such exist.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Mar-2021
• ICS: 17.040.20 - Properties of surfaces
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.10 - Test Methods

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: B568 − 98 (Reapproved 2021)
Standard Test Method for
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Measurement of Coating Thickness by X-Ray Spectrometry
This standard is issued under the fixed designation B568; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 2. Referenced Documents
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2.1 ASTM Standards:
1.1 ThistestmethodcoverstheuseofX-rayspectrometryto
E135 Terminology Relating to Analytical Chemistry for
determinethicknessofmetallicandsomenonmetalliccoatings.
Metals, Ores, and Related Materials
1.2 The maximum measurable thickness for a given coating
2.2 International Standard:
is that thickness beyond which the intensity of the character-
ISO 3497 Metallic Coatings—Measurement of Coating
istic secondary X radiation from the coating or the substrate is
Thickness—X-ray Spectrometric Methods
no longer sensitive to small changes in thickness.
3. Terminology
1.3 This test method measures the mass of coating per unit
area, which can also be expressed in units of linear thickness
3.1 Definitions of technical terms used in this test method
provided that the density of the coating is known.
may be found in Terminology E135.
1.4 Problems of personnel protection against radiation gen-
4. Summary of Test Method
erated in an X-ray tube or emanating from a radioisotope
4.1 Excitation—The measurement of the thickness of coat-
source are not covered by this test method. For information on
ings by X-ray spectrometric methods is based on the combined
this important aspect, reference should be made to current
interaction of the coating and substrate with incident radiation
documents of the National Committee on Radiation Protection
of sufficient energy to cause the emission of secondary radia-
and Measurement, Federal Register, Nuclear Regulatory
tions characteristic of the elements composing the coating and
Commission, National Institute of Standards and Technology
substrate.The exciting radiation may be generated by an X-ray
(formerly the National Bureau of Standards), and to state and
tube or by certain radioisotopes.
local codes if such exist.
4.1.1 Excitation by an X-Ray Tube—Suitableexcitingradia-
1.5 This standard does not purport to address all of the
tion will be produced by an X-ray tube if sufficient potential is
safety concerns, if any, associated with its use. It is the
appliedtothetube.Thisisontheorderof35to50kVformost
responsibility of the user of this standard to establish appro-
thickness-measurement applications. The chief advantage of
priate safety, health, and environmental practices and deter-
X-ray tube excitation is the high intensity provided.
mine the applicability of regulatory limitations prior to use.
4.1.2 Excitation by a Radioisotope —Of the many available
1.6 This international standard was developed in accor-
radioisotopes, only a few emit gamma radiations in the energy
dance with internationally recognized principles on standard-
range suitable for coating-thickness measurement. Ideally, the
ization established in the Decision on Principles for the
exciting radiation is slightly more energetic (shorter in wave-
Development of International Standards, Guides and Recom-
length) than the desired characteristic X rays. The advantages
mendations issued by the World Trade Organization Technical
of radioisotope excitation include more compact instrumenta-
Barriers to Trade (TBT) Committee.
tion essentially monochromatic radiation, and very low back-
ground intensity. The major disadvantage of radioisotope
excitation is the much lower intensities available as compared
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ThistestmethodisunderthejurisdictionofASTMCommitteeB08onMetallic
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 on
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Test Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved April 1, 2021. Published May 2021. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approvedin1972.Lastpreviouseditionapprovedin2014asB568 – 98(2014).DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/B0568-98R21. the ASTM website.
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B568 − 98 (2021)
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