Effects of Bi₂O₃ Doping on the Mechanical Properties of PbO Ceramic Pellets Used in Lead-Cooled Fast Reactors

In this paper, the effects of Bi₂O₃ doping on the mechanical properties of PbO ceramic pellets were studied. Different ratios of Bi₂O₃/PbO (i.e., xBi₂O₃-(1-x) PbO, where x is 0, 1, 3, 5, or 7 wt.%) were fabricated and sintered at 570, 620, and 670 °C. Mechanical properties including density, hardness, flexural strength, and sintering of PbO were studied for each of the aforementioned compositions. Phase composition, microstructure, and the worn surfaces of the composites were characterized by scanning electron microscopy and X-ray diffraction (XRD). The XRD analysis revealed that a solid solution formed in the composite ceramic. The best suited conditions of temperature and doping of Bi₂O₃ for optimal sintering were found to be 620 °C and 3 wt.%, respectively. The hardness of the 3 wt.% Bi₂O₃-97 wt.% PbO ceramic was found to be 717 MPa, which is about four times higher than the hardness of pure PbO. In addition, the strength of the composites was found to be 43 MPa, which is two times higher than that of pure PbO. The integrity of the composites was verified using the lead-bismuth eutectic alloy flushing experiment. The results of this research paper are important for future studies of oxygen control in the lead-bismuth eutectic alloy of lead-cooled fast reactors.