Acoustic Emission in Zirconium Hydrogenation Process

Abstract—The acoustic emission signals that arise during the interaction of metal zirconium samples with hydrogen, as well as the changes that occur in hydrogenated samples and are sources of high-amplitude acoustic signals, are studied. Hydrogenation of pieces of compact zirconium iodide ranging in size from 5 to 10 mm, shavings obtained from compact zirconium iodide with a linear particle size from 2 to 3 mm and a thickness of ≈0.2 mm, "coarse" electrolytic zirconium powder with a fraction from 80 to 550 μm, and "fine" electrolytic zirconium powder with a particle size of less than 80 μm is carried out. It is 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 the initial materials. Cracking and grinding are caused by deformation and internal stresses that arise in the samples owing 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 the acoustic emission signal naturally increases in the series pieces of compact zirconium iodide–shavings of zirconium iodide–"coarse" electrolytic zirconium powder–"fine" electrolytic zirconium powder, which is in good agreement with the results of earlier similar studies carried out on the hydrogenation of titanium metal samples.