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ASTM D7639-2018 pdf free download

ASTM D7639-2018 pdf free download.Standard Test Method for Determination of Zirconium Treatment Weight or Thickness on Metal Substrates by X-Ray Fluorescence
1. Scope
1.1 This test method covers the use of X-ray fluorescence (XRF) spectrometry for the determination of the mass of zirconium (Zr) coating weight per unit area ofmetal substrates. 1.2 Coating treatments can also be expressed in units of linear thickness provided that the density of the coating is known, or provided that a calibration curve has been estab- lished for thickness determination using standards with treat- ment matching this of test specimens to be analyzed. For simplicity, the method will subsequently refer to the determi- nation expressed as coating weight. 1.3 XRF is applicable for the determination of the coating weight as zirconium or total coating weight of a zirconium containing treatment, or both, on a variety of metal substrates. 1.4 The maximum measurable coating weight for a given coating is that weight beyond which the intensity of the characteristic X-ray radiation from the coating or the substrate is no longer sensitive to small changes in weight. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.7 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
5. Apparatus
5.1 X-Ray Fluorescence Spectrometer, capable ofmeasuring the intensity of zirconium Ka or La line, and establish the relationship between peak intensity and coating weight. The spectrometer’s design must include, as a minimum, the follow- ing features: 5.1.1 Source ofX-Ray Excitation, X-ray tube with excitation above 2.55 keV if measuring the zirconium La line, or above 18 keV if measuring the zirconium Ka line. 5.1.2 X-Ray Detector, with high sensitivity and capable of discriminating between zirconium La or Ka radiation and other X-rays of higher or lower energies. In the case of wavelength dispersive X-ray fluores- cence (WDXRF), this can be an analyzing crystal (for example, fixed channel, goniometer) setup to detect the zirconium X-rays (La or Ka line). Germanium 111 has been found to be acceptable for the Zirconium La line and LiF220 or LiF200 for the zirconium Ka line. In the case of energy dispersive X-ray fluorescence (EDXRF), it can be a proportional counter, or a semiconductor such as a PIN diode or a silicon-drift detector. 5.1.3 Pulse-Height Analyzer, or other means of energy discrimination. 5.1.4 Optical Path, specified by manufacturer. A helium or vacuum path is recommended when measuring the zirconium La line in order to minimize the attenuation of the X-rays by the air in the optical path. The zirconium Ka line has a higher energy and its intensity will not be affected by air. 5.1.5 Signal Conditioning and Data Handling System, whereby a coating weight versus X-ray counts curve may be established within the system for the direct readout of coating weight. 5.1.6 Sample Spinner (optional), to reduce the effects of coating weight variation across the test specimen.

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