Warning: Problems concerning protection of personnel against X-rays are not covered by this standard. For information on this important aspect, reference should be made to current international and national standards, and to local regulations, where these exist.
1.1 This standard specifies methods for measuring the thickness of metallic coatings by the use of X-ray spectrometric methods.
1.2 The measuring methods to which this standard applies are fundamentally those that determine the mass per unit area. If the density of coating material is known, the results of measurements can also be expressed as linear thickness of the coating.
1.3 The measuring methods permit simultaneous measurement of coating systems with up to three layers, or simultaneous measurement of thickness and compositions of layers with up to three components.
1.4 The practical measurement ranges of given coating materials are largely determined by the energy of the characteristic X-ray fluorescence to be analyzed and by the acceptable measurement uncertainty and can differ depending upon the instrument system and operating procedure used.
2 Terms and Definitions
For the purposes of this standard, the following terms and definitions apply.
2.1
X-ray fluorescence (XRF)
secondary radiation occurring when a high intensity incident X-ray beam impinges upon a material placed in the path of the incident beam
Note: The secondary emission has wavelengths and energies characteristic of that material.
2.2
intensity of fluorescent radiation
radiation intensity, x, measured by the instrument, expressed in counts (radiation pulses) per second
2.3
saturation thickness
thickness that, if exceeded, does not produce any detectable change in fluorescent intensity
Note: Saturation thickness depends upon the energy or wavelength of the fluorescent radiation, density and atomic number of the material and on the angle of incident and fluorescent radiation with respect to the surface of the material.
2.4
normalized intensity xn
ratio of the difference in intensity obtained from a coated test specimen, x, and an uncoated basis material, x0, and the difference obtained from a material of thickness equal to or greater than the saturation thickness, xs (see 2.3) and an uncoated basis material, x0, all measured under the same conditions
GB/T 16921-2005 The following standards are cited：
