掺钆铈独居石陶瓷固化体在 TH MC耦合作用下的化学稳定性

摘要

以氧化钆、十水草酸铈和磷酸二氢铵为原料，采用热压烧结制备掺钆铈独居石陶瓷固化体，借助X射线衍射（XRD）、场发射扫描电镜（FESEM）、能谱（EDS）和电感耦合等离子体发射光谱‐质谱（ICP‐MS）等分析手段，研究掺钆铈独居石陶瓷固化体的热压烧结及固化体在热‐水‐力‐化学（THMC）耦合作用下的化学稳定性。结果表明，采用热压烧结技术，实现了单相Ce0.9Gd0.1PO4陶瓷固化体的低温（1150～1200℃）、快速（2h）烧结，固化体的相对密度达99.62％；在THMC耦合作用下（温度为90～200℃（0.101～1.554MPa），pH＝5～9），固化体具有优异的化学稳定性，浸出时间为42d时，模拟次锕系核素Gd的归一化浸出率在10－6～10－5g／（m2·d）数量级；温度和pH值对Ce的归一化浸出率影响较小；温度对Gd的归一化浸出率没有影响；与弱碱性（pH＝9）水溶液相比，在弱酸性（pH＝5）和中性（pH＝7）水溶液中，Gd的归一化浸出率相对较高。%The Gd‐doped monazite‐Ce ceramic forms were prepared by hot‐pressing using Ce2(C2O4)3 ·10H2O ,NH4H2PO4 and Gd2O3 as raw materials .The hot‐pressing sintering and chemical durability of the ceramic forms under the coupling effect of ther‐modynamics‐hydrodynamics‐mechanics‐chemistry (THMC) were investigated by means of XRD ,FESEM ,EDS ,ICP‐MS and so on .The results show that the single monazite‐type Ce0.9 Gd0.1 PO4 phase is obtained by hot‐pressing at 1 150‐1 200 ℃ for 2 h .The rela‐tive density of the ceramic form is 99.62% .Furthermore ,the ceramic forms exhibit excellent chemical durability under the coupling effect of T HMC (90‐200 ℃ (0.101‐1.554 MPa) ,pH = 5‐9) .The normalized leaching rate (LR) of Gd is 10-6‐10-5 g/(m2 · d) orders of magnitude on the 42nd day .Both leaching temperature and pH value have little influence on the LR of Ce ,while the leaching temperature has no effect on the LR of Gd .The LR of Gd is relatively higher in weakly acidic (pH=5) and neutral (pH=7) water solution than that in weakly alkaline (pH=9) water solution .