Carbon black densified matrix graphite to enhance its anti-infiltration capability against molten salt

A novel graphite matrix was prepared by adding carbon black (CB) as a densification agent to traditional matrix A3-3 graphite preparation. The particle size of CB densifier we chose was approximately 50–150 nm, which was smaller than the pore diameter of densified matrix graphite (500-1000 nm). Five different mass fractions of CB were mixed and compared with as-received A3-3 by various characterization methods, which indicated that CB can effectively fill the pores of A3-3 and improve its anti-infiltration capability against molten salt (fluoride salt for molten salt reactor and heat storage salt). Meanwhile, considering the requirements for A3-3 graphite in scenarios of solid fuel molten salt reactor and thermal energy storage system, all the samples were compared as well before and after purification. The results showed that purification treatment resulted in slight increase of the pore size and open porosity of graphite and thus weakened its anti-infiltration capability against molten salt, but the thermal properties of graphite improved inversely. However, the addition of excessive CB could cause the significantly decline of thermal properties of A3-3. Comprehensively considering the anti-infiltration effect and requirements of thermal properties, adding 5 % CB was the most preferrable choice for the matrix graphite before and after purification.