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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ASTM B – 98 Standard Test Method for Measurement of Coating Thickness by X-Ray Spectrometry
Calibration standards having the same radius of curvature as that of the test specimens can also be used to eliminate curvature effects. Last previous edition approved in as B — The corresponding standard deviation in the thickness measurement is a function of the slope of the calibration curve at the point of measurement.
Depending upon the atomic number of the coating, when the asrm thickness is increased to a certain value, the characteristic radiation from the substrate will disappear, although a 2 Copyright by ASTM Int’l all rights reserved ; Reproduction authorized per License Agreement with Victoria Boyer ; Wed Mar 23 The measurement of a coating thickness by X-ray absorption is not applicable if an intermediate coating is present because of the indeterminate absorption effect of intermediate layer.
Instrument measurement precision will rapidly decrease with increasing thickness in the hyperbolic range. In those cases where the measurement of thickness on curved surfaces cannot be avoided, a asrm should be used on the excitation beam, reducing the measurement area to a size that will minimize the effects of curvature. In the curve shown in the Appendix, see Fig. The instrument calibration may be made h568 standards of silver on nickel.
If instability is suspected, a series of twenty or more count measurements should be made on b5668 same specimen without moving the specimen and the standard deviation of the series calculated. The relationship between these units is as follows: Results are reported in a table with five or more readings per sample.
In all, thirteen 13 factors are highlighted and worth knowing about in case issues occur. The stated mass per unit area of each coating thickness SRM is certi? This does not mean that the result would necessarily be ten times as accurate see 7.
Most commercially available instruments display the standard deviation directly in units of thickness. This type of detector is maintained at a very low qstm in a liquid-nitrogen cryostat 77K. Some forms of instability become evident if the same specimen is measured periodically.
ASTM B – PLATING THICKNESS BY XRF TESTING SERVICES
Calibrate it in accordance with Section 7. In a suitable detector see 4.
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 depending on the width of the emission peak usually displayed on the face of a cathode ray tube. In no case shall the measurement area be larger than the coated area available on the test specimen.
If all of the other variables are? To reduce the statistical error to an acceptable level, it is necessary to use a counting interval long enough to accumulate a sufficient number of counts. To understand the signi? It is, therefore, no greater than, and attributable to: The emission now being measured comes from the substrate.
This method is frequently used to measure gold thickness, platinum thickness, nickel thickness, or zinc thickness over metallic substrates. It is possible to correct for dead-time losses. Care must be taken that the coating and substrate are thick enough to prevent the primary X-ray beam from reaching and?
However, if the method is based sstm intensity ratios rather than absolute intensities, minor variations in excitation energy are compensated for. Measuring coating thickness was one of the first applications of x-ray fluorescence spectrometry and is still one of the most common uses of the technology. Protective coatings such as lacquer adtm chromate conversion coatings over the coating to be measured will also affect the results. Variations in atm can result either from variations in composition or from variations in plating conditions see 6.
Avoid specimen areas having visible defects such as? Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend.
ASTM B568 (measurement of coating thickness by XRF)
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 of the standards. Eastern Applied Research, Inc. This can be Copyright? The conversion is made automatically by most commercial coating thickness instruments. It can be used to measure coating and base combinations that are not readily measured by other techniques.
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. Factors Affecting Accuracy 6. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters.
Material testing you can trust since It is recommended that two sets of standards be maintained, that is, a set of primary standards and a set of working standards. This standard less measurement shall be corrected by means of calibration standards. 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.
This standard has been approved for use by agencies of the Department of Defense. 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.