5 / 2020-04-09 16:38:10

Cold spray solid-state additively manufactured Al/B4C composite for neutron absorption in spent fuel storage

Cold spray, Al/B4C composite, Neutron absorption, spent fuel absorption, B4C content.

全体主题 > Material Degradation and Mitigation for Aged Nuclear Plants

Al/B4C composite plate prepared by hot-pressing sintering has been practically inserted in stainless-steel spent fuel storage frames for neutron absorption. However, the present Al/B4C is always in a plate shape and thus cannot meet the requirement in tanks with relatively complex geometry. Meanwhile, the hot-pressing sintering process makes the B4C content lower than 35 vol.% resulting in a limited neutron absorption ability. In the present work, a cold spray solid-state additive manufacturing (CS-AM) technique was employed to construct Al/B4C composite coating on stainless steel with Al/B4C composite powder. The Al/B4C powder was prepared by mechanical milling process with commercial Al and B4C powders. Coating microstructure was characterized with scanning electron microscopy. The results show that the Al/B4C coating with a high B4C content of 45vol.% can be achieved by CS-AM, which is much higher than that in hot-pressing sintered counterparts. Flaws such as pores or cracks were not observed within the coating and the coating/substrate interface. The size of the B4C particle in the composites ranges from 0.2 to 2 micrometers. Owning to the low processing temperature, the unexpected chemical reaction between B4C and Al was not detected. The adhesion of the coating was tested according to ASTM C 633 Standard and yielded an average bonding strength of 54.5 MPa. Since compressive residual stress can be formed in the coating, the coating thickness can be as high as tens of mm. The Al/B4C composite coating can be deposited on steel surface with relatively complex geometry. This study provides a novel and flexible approach to prepare Al/B4C composite coating with high content of B4C. This could save more space for spent fuel storage as compared with inserting Al/B4C plate.Due to the low processing temperature and flexibility, CS-AM can be also used for in-site deposition or repair of the failed parts.