Effects of PVB addition on PbO ceramics used in lead-cooled fast reactors

The lead oxide (PbO) ceramics play an important role in the solid-phase oxygen control system of the lead-cooled fast reactor. But sintering process and properties of PbO ceramics are rarely studied. In this paper, the effects of PVB addition on the mechanical properties and microstructure of PbO ceramics are studied. PbO ceramic specimens added with x wt.% (the value of x is 0, 1, 2, 4 or 6) PVB solution, a kind of binder, are fabricated, debonded and sintered at 620 °C. The results reveal that compared with pure PbO ceramics, the addition of PVB solution improves the mechanical properties such as hardness, flexural strength, density, and the microstructure of PbO ceramics according to scanning electron microscopy images. The optimal relative density and flexural strength are found to be 90.16% and 26.33 MPa with 4 wt% PVB solution, respectively. And the optimum hardness of 1212.58 MPa is achieved with 2 wt% PVB solution. Lastly, the sintered PbO particles are placed in a pool-type LBE flowing set-up to check the integrity of the shape and change of microstructure. The results of flushing experiment show that most PbO ceramics with PVB solution can maintain the shape integrity in spite of the appearances of some internal cracks.