The sintering conditions using hot isostatic press (HIP) of yttria-stabilized zirconia (YSZ) were investigated to obtain a dense YSZ layer at low sintering temperature such as 1000°C for an electrolyte of metal-supported solid oxide fuel cell. It was found that a dense YSZ pellet with relative density of 93% could be obtained under a sintering condition of 1000°C-10 hours with HIP in 195 MPa. On the other hand, in X-ray diffraction analysis of the dense YSZ pellet, peaks of the monoclinic phase were slightly detected in addition to peaks of the cubic phase. From energy dispersive X-ray spectroscopy analysis, a small amount of boron was detected in the dense YSZ pellet. It is considered that the YSZ crystalline phase transformation of cubic to monoclinic phase was occurred by the boron diffusion from the diffusion barrier coating of metal foil capsule used for the HIP.
Manabe et al. (Thu,) studied this question.