A comparative study of conventionally sintered, microwave sintered and hot isostatic press sintered NZP and CZP structures interacted with fluoride

Sodium zirconium phosphate and calcium zirconium phosphate, two potential radioactive wasteforms, were treated with fluoride, and different methods of sintering were evaluated. Different compositions were prepared by adding calcium fluoride to sodium zirconium phosphate and sodium fluoride to calcium zirconium phosphate. These mixtures were calcined in a microwave furnace and then sintered. The increase in densification of the samples sintered in a hot isostatic press were observed to be nearly uniform, while other samples that were sintered in a microwave and in a resistance furnace were inhomogeneous. The concentration of inhomogeneities was higher in fluorinated samples prepared under closed conditions in a hot press than samples prepared under microwave conditions in air.