Acoustic Emission in Zirconium Hydrogenation Process

Abstract

Acoustic emission signals occurring during the interaction of zirconium metal samples with hydrogen, as well as changes occurring in hydrogenated samples and being sources of high-amplitude acoustic signals, have been studied. The hydrogenation of pieces of compact iodide zirconium with a size from 5 to 10 mm, chips obtained from compact iodide zirconium with a linear particle size from 2 to 3 mm and a thickness of 0.2 mm, a «large» powder of electrolytic zirconium of a fraction from 80 to 550 microns and a «small» powder of electrolytic zirconium with a particle size of less than 80 microns was carried out. It has been established that the source of high-amplitude acoustic signals in all cases is the cracking of zirconium particles at the macro level, which leads to the formation of extended cracks and fractures on the surface of individual particles, as well as to the grinding of original materials. Cracking and grinding are caused by deformation and internal stresses occurring in the samples due to an increase in the volume of the solid phase during hydrogenation. It is shown for the first time that the atomic ratio [H] / [Zr] in the solid phase, corresponding to the maximum amplitude of a acoustic emission signal, naturally increases in a series: pieces of compact iodide zirconium-chips of iodide zirconium-«large» powder of electrolytic zirconium-«small» powder of electrolytic zirconium, which is in good agreement with the results of previous studies similar studies on the hydrogenation of titanium metal samples.