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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The X-ray absorption method cannot be used when one or more intermediate coating layers are present. To understand the signi? Precision and Bias The advantages of radioisotope excitation include more compact instrumentation essentially monochromatic radiation, and very low background intensity.
ASTM B568 (measurement of coating thickness by XRF)
This error is independent of other sources of error such as those arising from mistakes on the part of the operator or from the use of inaccurate standards. The intensities are background-corrected, that is, the intensity for Ni Ka is obtained from a sample of the unplated brass substrate and subsequently substracted for each of the intensity readings obtained from electroplated samples. An increase in plating thickness results in a larger peak from the plating material and a smaller peak from the base material.
Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. The value should not be signi? Exceptions are allowed if the intensity of the characteristic coating material emission is not in?
In those cases asym 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.
ASTM B – 98 Standard Test Method for Measurement of Coating Thickness by X-Ray Spectrometry
In general, the radiation intensity varies directly with the current and the square of the potential. It is necessary, therefore, to have a means of separating the desired components so that their intensities can be measured. The stated mass per unit area of each coating thickness SRM is certi? This type of detector is maintained at a very low temperature in a liquid-nitrogen cryostat 77K.
These should be used only to calibrate and periodically check the condition of the working standards. Operation of the gas-? Summary of Test Method 4. In a suitable detector see 4. This standard has been approved for use by agencies of the Department of Defense. Typical examples of such combinations are gold on nickel on copper and nickel on copper on steel.
This method sometimes is described as numerical? The situation is similar for the absorption curve shown in the Appendix, see Fig. If there is a change of the measured thickness that is large enough to preclude meeting the requirements of Section 11, recalibrate the instrument.
The major disadvantage of radioisotope excitation is the much lower intensities available as compared with X-ray tube sources. The standards correction procedure calibration performs the same way as the procedure used for establishing empirical instrument calibrations alone.
The sources of error will be eliminated by the use of calibration standards electroplated in the same type of solution under the same conditions as those used in the production of the coatings to be 3 Copyright by ASTM Int’l all rights reserved ; Reproduction authorized per License Agreement with Victoria Boyer ; Wed Mar 23 In an energydispersive system, the multichannel analyzer is set to accumulate the pulses comprising the same energy peak.
From six to sixty adjacent channels can be used to store the pulses representing a selected characteristic emission of one element, the number of channels aatm on the width of the emission peak usually displayed on the face of a cathode ray tube.
The exact relationship between the measured intensity and the coating thickness must be established by the use of standards having the same coating and substrate compositions as the samples to be measured. If the coating on the standard is gold, but not electroplated under conditions known to be the same as the coating being measured, the X-ray properties may be atsm to be the same for mass per unit area measurements.
Results are reported in a table with five or more readings per sample. Under such circumstances, thickness measurements must be corrected for density differences, unless density differences can be shown to be insigni?
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. Ideally, the exciting radiation is slightly more energetic shorter in wavelength than the desired characteristic X rays. Our laboratory also provides laboratory services for plastic testingmetal testingrubber testingawtm testingpaint testingplating testingadhesive testingcircuit board testingand other testing.
Some forms of instability become evident if the same specimen is measured periodically. A superscript epsilon e indicates an editorial change since the last revision or reapproval.
Care adtm be taken that the coating and substrate are thick enough to prevent the primary X-ray beam from reaching and? This limiting thickness depends, in general, upon the energy of the characteristic X-ray and the density and absorption properties of the material under analysis. However, if the method is based on intensity ratios rather satm absolute intensities, minor aastm in excitation energy are compensated for.
If all of the other variables are?
The intensity of the emitted secondary X radiation depends, in general, upon the excitation energy, the atomic numbers of the coating and substrate, the area of the specimen exposed astj the primary radiation, the power of the X-ray tube, and the thickness of the coating. This gives rise to the statistical error which is inherent in all radiation measurements.
Last previous edition approved in as B — However, when thickness measurements are made by the X-ray absorption method the substrate composition of the test specimens must be the same as that ast the standards.
It is possible to correct for dead-time losses. If pores or voids are present, X-ray methods will give an indication of coating mass per unit area but not of thickness. Advanced Plastic and Material Testing, Inc. If the average of the? 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.
If the standards are visibly scratched or abraded they should be replaced. 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 b5688.
Instrument measurement precision will rapidly decrease with increasing thickness in the hyperbolic range. This procedure is commonly used for the measurement of hard gold coatings having a density of The intensities are background-corrected as they were in the emission technique. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters.