A Thickness Determination Method Based on Energy-Dispersive X-Ray Fluorescence and Application in Zirconium Alloy Coatings

Precise control and characterization of coating thickness are critical for the reliability and structural integrity of zirconium alloy claddings in nuclear reactors. However, conventional techniques such as scanning electron microscopy (SEM) and metallographic microscopy are often limited by low efficiency, complex sample preparation, and destructive testing. This study proposes a fundamental parameter method based on energy-dispersive X-ray fluorescence. It is designed for the rapid, accurate, and non-destructive determination of zirconium alloy coating thickness. X-ray fluorescence intensity is theoretically calculated from measurement conditions and fundamental parameters, with consideration of absorption-enhancement effects from primary and secondary fluorescence. Quantitative thickness is obtained through iterative calculations until the measured intensity agrees with the theoretical intensity. Using this method, a series of chromium coatings with different thicknesses deposited on zirconium substrates were analyzed. The relative error of the calculated thickness was within ±5% for most samples compared with cross-sectional SEM results, demonstrating the accuracy of the proposed method.