ASTM B – Designation: B – 98 (Reapproved ) UNCONTROLLED (if printed out) Standar. Basic Description: ASTM B X-Ray Fluorescence (XRF) is a non-destructive method of measuring plating thickness by using an X-ray beam to excite the. Designation: B − 98 (Reapproved ) Standard Test Method for This test method is under the jurisdiction of ASTM Committee B08 on Metallic.
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X-ray tubes typically have intensities that are several orders of magnitude greater than radioisotope sources. Summary of Test Method 4.
ASTM B – PLATING THICKNESS BY XRF TESTING SERVICES
If all of the other variables are? Due to the low intensity of radioisotopes, they are unsuitable for measurements on small areas less than 0. Published data in tabular form are available that relate spectrogoniometer settings to the characteristic emissions of elements for each of the commonly used analyzing crystals. Or the simultaneous measurement of thickness and compositions of layers with up to three components.
Suitable means must be provided to perfectly align the test specimen relative to the excitation beam. It must be established experimentally that the minimum thickness requirements have been met for a particular substrate-source combination, although it is sometimes possible to back up the test specimen substrates with a sufficient thickness of materials of the same composition. It is recommended that two sets of standards be maintained, that is, a set of primary standards and a set of working standards.
In a suitable detector see 4. Similarly, the detector may also be masked so that it will see only that area of the specimen on which the coating thickness is to be determined.
ASTM B (measurement of coating thickness by XRF) | Eastern Applied Research, Inc.
Other disadvantages include the limited number of suitable radioisotopes, their rather short useful lifetimes, and the personnel protection problems associated with highintensity radioactive sources.
The maximum thickness that can be measured by this method is somewhat less than what is, effectively, in? The precision rapidly becomes poorer in the portion of the curve above approximately 10?
If the coating on the standard adtm gold, but not electroplated under conditions known to be the same bb568 the coating being measured, the X-ray properties may be assumed to be the same for mass per unit area measurements. Calibration standards having the same radius of curvature as that of the test specimens can also be used to eliminate curvature effects.
If there is a change of the measured thickness that is large enough to preclude meeting the requirements of Section 11, recalibrate the instrument. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below. The intensity of the emitted secondary X radiation depends, in general, upon the excitation energy, the atomic numbers of the coating ashm substrate, the area of the specimen exposed to the primary radiation, the power of the X-ray tube, and the thickness of the coating.
However, the general shapes of calibration curves in the emission mode and in the absorption mode of operation are given here as general information. Each element emits energy at a different wavelength so the plating b58 base material show separate peaks in the XRF spectrum. The intensity of the characteristic silver emission is not in?
Typical examples of such combinations are gold on nickel on copper aetm nickel on copper on steel. If not, make sure that the calibration has been made with a substrate having the same thickness and emission properties as the test specimens. The benefit to operators is that it details the variations in x-ray spectrometry systems and explains how XRF works with some terminology that may be useful.
However, the ASTM B standard also details some variables that an operator may not think of; such as sample curvature, substrate composition, and axtm cleanliness. The chief advantage of X-ray tube excitation is the high intensity provided.
This industry standard ASTM B should be reviewed by all operators of x-ray fluorescence because it offers a beneficial overview n568 highlights proper implementation of the technology.
Acceptable energy resolution for most thickness measurement requirements can be realized with proportional counters, and these detectors are being used on most of the commercially available thickness gages based on X-ray spectrometry. Factors Affecting Accuracy 6.
This procedure is commonly used for the measurement of hard gold coatings having a density of Xstm type of detector is maintained at a very low temperature in a liquid-nitrogen cryostat 77K. If the coating of the standards is electrodeposited from the same bath and under the same conditions as the coating to be measured, the X-ray properties may be assumed to be the same.
ASTM B568 (measurement of coating thickness by XRF)
The relationship between these units is as follows: Therefore, in any method based on a simple relationship between intensity and thickness, the? Thus, would give a standard deviation indicating 10 times the precision one-tenth the standard deviation obtained from counts.
Precision and Bias This is because both the exciting and secondary characteristic radiations undergo attenuation in passing through the coating. In those cases where the measurement of thickness on curved surfaces cannot be avoided, a collimator should be used on the excitation beam, reducing the measurement area to a size that will minimize the effects of curvature. The X-ray absorption method cannot be used when one or more intermediate coating layers are present.
It is possible to correct for dead-time losses.
A minimum area of 0. The intensity will be a maximum for a sample of the uncoated basis metal and will decrease with increasing coating thickness.
Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility.
This gives rise to the statistical error which is inherent in all radiation measurements. When an energy-dispersive system is being used it should be recognized that a signi? In consequence, an estimate of the counting rate based on a short counting interval for example, 1 or 2 s may be appreciably different from an estimate based on a longer counting period, particularly if the counting rate is low. Both of the techniques described below are based on the use of primary standards of known coating thicknesses which serve to correlate quantitatively the radiation intensity and thickness.
An example of this situation is the measurement of silver on copper.