Low-temperature reactive hot-pressing of cerium-doped titanate composite ceramics and their aqueous stability

摘要

Reactive hot-pressing was scarcely applied to fabricate titanate ceramic waste forms designed for immobilizing high-level radioactive waste (HLW). However, compared with non-reactive processes, there is an advantage of producing high-dcnsity ceramics at reduced temperatures by reactive hot-pressing. Ce~(IV)-doped titanate composite ceramics with relative densities in excess of 99% were prepared by reactive hot-pressing at temperature as low as 1150 ℃ and pressure of 30 MPa for 1-4 h. The results show that low-tempcrature densification of the composite ceramics might be attributed to the plastic deformation under hot-pressing condition. In addition, aqueous stability testing was carried out using the standard MCC-1 static leach test method. The results demonstrate that the normalized elemental leach rate of Ca, Ce and Zr were fairly constant in a low value below 5 x 10~(-2) g m~(-2) d~(-1), 7 x 10~(-6) g m~(-2) d~(-1) and 6 x 10~(-6) g m~(-2) d~(-1) after 21 d.