Hot-pressed phosphate glass–ceramic matrix composites containing calcium phosphate particles for nuclear waste encapsulation |
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Authors: | E M Michie R W Grimes A R Boccaccini |
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Affiliation: | (1) Department of Materials, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK |
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Abstract: | Sodium aluminium phosphate (NaAlP) glass–ceramic composites were produced as potential wasteforms for the immobilization of
special categories of halide-containing radioactive waste. Sintering conditions for encapsulating a simulated waste (a calcinated
mixture of calcium phosphate host and various oxides) in the cold-pressed NaAlP glass–ceramic were first determined and the
results were compared with similar samples prepared by hot pressing. In both cases, the conditions aimed to provide a very
high-density material, via as low production temperatures as possible, in conjunction with a high waste loading (75 wt.% simulated
waste to 25 wt.% glass). It was found that by hot pressing and using a NaAlP glass–ceramic containing 2 mol% B2O3, significantly lower temperatures could be employed compared to the cold pressing and sintering route. The lowest temperature
at which a sufficiently dense hot-pressed product was achieved (86% theoretical density), that exhibited mechanical properties
similar to those of borosilicate glass (e.g. Young’s modulus 67 ± 2 GPa), was 550 °C. This processing temperature is considerably
lower than values reported in the literature for similar systems. As such, hot pressing can be considered as a convenient
technique for the fabrication of this type of composite for waste encapsulation. |
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