Characteristics of ZrO₂ added-MgAl₂O₄ ceramics for matrix of inert matrix nuclear fuel (IMF)

Some ZrO₂ added-MgAl₂O₄ ceramics for inert matrix of inert matrix nuclear fuel (IMF) had been fabricated from powders prepared using precipitation method. Effect of ZrO₂ addition on crystal structure, microstructure and mechanical properties of the ZrO₂ added-MgAl₂O₄ ceramics was studied. The ceramics were prepared by mixing ZrO₂, MgO and Al₂O₃ followed by pressing and sintering. The concentrations of ZrO₂ additive were 0, 5, 10 and 15 mole %. The mixed powder was pressed into green pellets with pressure of 4 ton/cm². The green pellets were sintered at 1600°C for 2 hours in air. The sintered pellets were evaluated visually. For microstructure examination, the fractured samples were examined using a scanning electron microscope (SEM). Crystal structure of the samples was analyzed using x-ray diffraction (XRD). Hardness and fracture toughness of the sintered pellets were determined using microindentation method with aid of a Vickers microhardness tester from Zwick. It was known that the sintered pellets were visually good. The XRD data showed that the ceramics crystallized in spinel cubic with second phase of ZrO₂. The hardness and fracture toughness of the ceramics increased with the increase of ZrO₂ concentration. (author)