正方晶ZrO_2多結晶体の高温変形におけるTiO_2及びGeO_2添加量依存性(第59回日本セラミックス協会進歩賞受賞に関する総説及び論文)

概要

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The doping dependence of high temperature plastic flow behavior in TiO_2-doped, GeO_2-doped and TiO_2 and GeO_2 co-doped tetragonal ZrO_2 polycrystal (TZP) was systematically examined at 1400℃ in air under an initial strain rate of 1.3×10^<-4>s^<-1>. The amount of dopant cations was in the range of 0.2-4mol%. The flow stress in the TZP decreases with the increasing doping amount in TiO_2 and/or GeO_2-doped TZP, but levels off over a 3mol% addition in the GeO_2-doped and TiO_2-GeO_2 co-doped TZP. The doping dependence of the flow stress in the TiO_2-GeO_2 co-doped TZP is close to that in the GeO_2-doped TZP rather than to that in the TiO_2-doped TZP; the flow stress in the GeO_2-doped and TiO_2-GeO_2 co-doped TZP is significantly lower than that in the TiO_2-doped TZP. The doped cations tend to segregate in the vicinity of the grain boundaries in TZP. The doping dependence of the flow stress is probably related to the amount of the grain boundary segregation of the dopant cations; the grain boundary segregation of the dopant cations is supposed to enhance the grain boundary atomic diffusion in the TZP, and hence the flow stress consequently decreases. On the other hand, elongation to failure in the TZP is highly improved by the TiO_2 and/or GeO_2 doping. The improved high temperature ductility of the TZP is attributed to the flow stress reduction due to the TiO_2 and/or GeO_2 doping.
社団法人日本セラミックス協会の論文
2006-02-01