金属铌对碳化锆陶瓷物相, 组织与力学性能的影响

Zirconium carbide (ZrC) has excellent nuclear radiation damage resistance and corrosion resistance. It is one of the most promising candidate materials for the fourth generation nuclear power system. However, its intrinsic characteristics of high melting point and low solid diffusion coefficient lead to its difficult sintering densification and high sintering temperature, which limits its wide application in nuclear energy system. In this paper, niobium was used as the additive, and its high sintering activity and solid solution with zirconium carbide were used to realize the low-temperature sintering densification of zirconium carbide ceramics. The results show that the dense single-phase (Zr, Nb)C solid solution ceramics can be obtained by sintering at 1800 ℃ when the amount of Nb is 20 vol%, and the flexural strength and fracture toughness are 200 MPa and 3.74 MPa•m^1/2, respectively. With the increase of Nb content, a certain amount of metal Nb is remained in the material to form (Zr, Nb)C-Nb composite, the residual metal Nb plays a role in inhibiting the growth of (Zr, Nb)C grain, which plays an obvious role in strengthening and toughening. The flexural strength and fracture toughness of the material increase with the increase of Nb content, and the fracture mode of the material changes from transgranular fracture to transgranular and intergranular mixed fracture.