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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Under such circumstances, thickness measurements must be corrected for density differences, unless density differences can be shown to be insigni? A minimum area of 0. In consequence, an estimate of the asfm 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.
Eastern Applied associates are available to help with safety radiation related asym and training if needed. The typical relationship between a coating thickness and the intensity of a characteristic emission from the coating metal is illustrated by the curve in the Appendix, Fig.
The relationship between these units is as follows: 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 astn specimen substrates with a sufficient thickness of materials of the same composition. 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.
If the standards are visibly scratched or abraded they should be replaced. Care must be taken that the aztm and substrate are thick enough to prevent the primary X-ray beam from reaching and? Last previous edition approved in as B — Instrument measurement precision will rapidly decrease with increasing thickness in the hyperbolic range. Typically, a channel may represent a span of 20 eV for a lithium-drifted silicon detector or to eV for a proportional counter.
However, the ASTM B standard also details some variables that an asstm may not think of; such as sample curvature, substrate composition, and surface cleanliness. Awtm standard has been approved for use by agencies of the Department of Defense.
From six aetm 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.
It also provides an overview of calibration techniques and best practices along with standard-less fundamental parameters calibrations. In no case shall the measurement area be larger than the coated area available on the test specimen.
To understand the signi? This method can be used when the energies of the detected characteristic radiations do not differ sufficiently for example, characteristic radiation from Au and Br. Results are reported in a table with five or more readings per sample. The maximum thickness that can be measured by this method is somewhat less than what is, effectively, in?
The exciting radiation may be generated by an X-ray tube or by certain radioisotopes. However, if the method is based on intensity ratios rather than absolute intensities, minor variations in excitation energy are compensated for.
However, when thickness is to be determined by the X-ray absorption technique, the thickness of the substrate must exceed a certain minimum or critical thickness. 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. The intensity will be a maximum for a sample of b5688 uncoated basis metal and will decrease with increasing coating thickness.
Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm. V568 that are certi?
ASTM B (measurement of coating thickness by XRF) | Eastern Applied Research, Inc.
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. The value should not be signi? Ideally, the exciting radiation is slightly more energetic shorter in wavelength than the desired characteristic X rays. Advanced Plastic and Material Testing, Inc. The intensity of the characteristic silver emission is not in? 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.
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. A superscript epsilon e indicates an editorial change since the last revision or reapproval. This shall be veri?
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)
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. 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 h568 readings obtained from electroplated samples.
The intensities are background-corrected as they asmt in the emission technique. The intensity of the emitted secondary X radiation depends, in general, upon the ashm energy, the atomic numbers of the coating and substrate, the area of the specimen exposed to the primary radiation, the power of the X-ray tube, and the thickness of the coating.
At coating thicknesses greater than atm 10? Variations in density can result either from variations in composition or from variations in plating conditions see 6.
Most modern industrial X-ray instrumentation will perform this calculation automatically. This procedure is commonly used for the measurement of hard gold coatings having a density of Most commercially available instruments display the standard deviation directly in units of thickness. The sample will always scatter some of these X rays into the detector. Other disadvantages include the limited number of suitable radioisotopes, their rather short useful lifetimes, and the personnel protection problems astk with highintensity radioactive sources.
Published data in tabular form are available that relate spectrogoniometer settings to the characteristic emissions of elements for b68 of the commonly used analyzing crystals. In an energydispersive system, the multichannel analyzer is set to accumulate the pulses comprising the same energy peak. If the average of the? In all, thirteen 13 factors are highlighted and worth knowing about in case issues occur.