Fabrication, characterization, and acid solubility of MgO-Nd2Zr2O7 composite ceramics for inert matrix fuel
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In the present paper, the ordered Nd2Zr2O7 pyrochlore was primarily synthesized by flux method and the MgO-Nd2Zr2O7 composite ceramics were fabricated subsequently through a conventional sintering route. A suite of characterization techniques, including XRD, Raman and BSE-EDS were employed to investigate the phase composition and microstructure of the as-prepared Nd2Zr2O7 and MgO-Nd2Zr2O7 samples. The acid solubility of the MgO-Nd2Zr2O7 composite ceramics was also tested. XRD results showed that the ordered Nd2Zr2O7 pyrochlore can be synthesized when the calcination temperature is in the range of 850–1200 °C. Raman results suggested that the chemical bonds of Nd2Zr2O7 pyrochlore get stronger, and more ordered structure can be gradually formed with the increase of calcining temperature. For the MgO-Nd2Zr2O7 composite ceramics, XRD results also showed that the Nd2Zr2O7 phase in the composite ceramics presents higher crystallinity degree and no other phase is formed after sintering at 1400–1550 °C. Moreover, BSE-EDS results indicated that the MgO-Nd2Zr2O7 composite ceramics are compact and dense, and the MgO and Nd2Zr2O7 phases are almost uniformly distributed between each other. In addition, the relative density of the bulk ceramics was about 96–98%, and it was concluded that ≥ 1500 °C could be the suitable sintering temperature to produce MgO-Nd2Zr2O7 composite ceramics. At last, the dissolution behavior of the ceramics in nitric acid solution revealed that only MgO in the MgO-Nd2Zr2O7 composite ceramics can be dissolved in the 11 M HNO3 solution within 24 h, and the dissolution rate was relatively low because of the high densification of the sample.
KeywordsMgO-Nd2Zr2O7 composite ceramics Inert matrix Flux method Characterization Fabrication
This work was supported by the National Natural Science Foundation of China (No. 11705153), the Foundation of Laboratory of National Defense Key Discipline for Nuclear Waste and Environmental Safety, Southwest University of Science and Technology (No. 17kfhk05), the Longshan Academic Talent Research Supporting Program of SWUST (No. 17LZX653), and National Training Program of Innovation and Entrepreneurship for Undergraduate (201710619017).
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