ASTM B568-98(2014)

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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Apr-2014
• ICS: 17.040.20 - Properties of surfaces
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.10 - Test Methods

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: B568 − 98 (Reapproved 2014)
Standard Test Method for
1
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 3. Terminology
1.1 ThistestmethodcoverstheuseofX-rayspectrometryto 3.1 Definitions of technical terms used in this test method
determinethicknessofmetallicandsomenonmetalliccoatings. may be found in Terminology E135.
1.2 The maximum measurable thickness for a given coating
4. Summary of Test Method
is that thickness beyond which the intensity of the character-
istic secondary X radiation from the coating or the substrate is 4.1 Excitation—The measurement of the thickness of coat-
no longer sensitive to small changes in thickness. ings by X-ray spectrometric methods is based on the combined
interaction of the coating and substrate with incident radiation
1.3 This test method measures the mass of coating per unit
of sufficient energy to cause the emission of secondary radia-
area, which can also be expressed in units of linear thickness
tions characteristic of the elements composing the coating and
provided that the density of the coating is known.
substrate.The exciting radiation may be generated by an X-ray
1.4 Problems of personnel protection against radiation gen-
tube or by certain radioisotopes.
erated in an X-ray tube or emanating from a radioisotope
4.1.1 Excitation by an X-Ray Tube—Suitableexcitingradia-
source are not covered by this test method. For information on
tion will be produced by an X-ray tube if sufficient potential is
this important aspect, reference should be made to current
appliedtothetube.Thisisontheorderof35to50kVformost
documents of the National Committee on Radiation Protection
thickness-measurement applications. The chief advantage of
and Measurement, Federal Register, Nuclear Regulatory
X-ray tube excitation is the high intensity provided.
Commission, National Institute of Standards and Technology
4.1.2 Excitation by a Radioisotope —Of the many available
(formerly the National Bureau of Standards), and to state and
radioisotopes, only a few emit gamma radiations in the energy
local codes if such exist.
range suitable for coating-thickness measurement. Ideally, the
exciting radiation is slightly more energetic (shorter in wave-
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the length) than the desired characteristic X rays. The advantages
of radioisotope excitation include more compact instrumenta-
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- tion essentially monochromatic radiation, and very low back-
ground intensity. The major disadvantage of radioisotope
bility of regulatory limitations prior to use.
excitation is the much lower intensities available as compared
2. Referenced Documents
with X-ray tube sources. X-ray tubes typically have intensities
2
that are several orders of magnitude greater than radioisotope
2.1 ASTM Standards:
sources. Due to the low intensity of radioisotopes, they are
E135 Terminology Relating to Analytical Chemistry for
unsuitable for measurements on small areas (less than 0.3 mm
Metals, Ores, and Related Materials
in diameter). Other disadvantages include the limited number
2.2 International Standard:
ofsuitableradioisotopes,theirrathershortusefullifetimes,and
ISO 3497 Metallic Coatings—Measurement of Coating
the personnel protection problems associated with high-
Thickness—X-ray Spectrometric Methods
intensity radioactive sources.
1
ThistestmethodisunderthejurisdictionofASTMCommitteeB08onMetallic
4.2 Dispersion—The secondary radiation resulting from the
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 on
exposure of an electroplated surface to X radiation usually
Test Methods.
contains many components in addition to those characteristic
Current edition approved May 1, 2014. Published May 2014. Originally
of the coating metal(s) and the substrate. It is necessary,
approvedin1972.Lastpreviouseditionapprovedin2009asB568 – 98(2009).DOI:
10.1520/B0568-98R14.
therefore, to have a means of separating the desired compo-
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
nents so that their intensities can be measured. This can be
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
done either by diffraction (wa
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