Vacuum activation assisted hydrogenation-dehydrogenation for preparing high-quality zirconium powder

The vacuum activation assisted hydrogenation-dehydrogenation (HDH) method was applied to fabricate the high-purity and ultrafine nuclear grade zirconium powders. An additional vacuum activation process was specially used prior to the hydrogenation to suppress the oxygen content and increase the hydrogen content. It was found that this extra process was not only efficient in shortening the length of the whole process, but also critical in improving the quality of Zr powders. The detailed investigations on the mechanism indicated that the merits could be both attributed to the removal of the oxygen sources on the sponge zirconium surface and the formation of micro-cracks on the ZrO2 film. By adjusting the parameters of the vacuum activation assisted HDH process, the oxygen content of the intermediate material ZrH2 was decreased down to 0.16wt.%, while the hydrogen content was increased up to 2.14wt.%, nearly approaching to the theoretical value. Based on this high-quality ZrH2 bulks, the Zr powders with oxygen content of 0.21wt.% and D-50 of similar to 2.9m could be fabricated after the ball-milling and dehydrogenation process. An efficient approach to produce high-quality Zr powders was systematically investigated in this paper to satisfy with the demand of the nuclear industry.