Sintering kinetics at constant rates of heating: effect of GeO₂ addition on the initial sintering stage of 3 mol% Y₂O₃-doped zirconia powder

摘要

The sintering behavior of 3 mol% Y₂O₃-doped zirconia powders with and without a small amount of GeO₂ was investigated to clarify the effect of GeO₂ addition on the initial sintering stage. The shrinkage of powder compact was measured under constant rates of heating (CRH). The sintering rate was accelerated by GeO₂ addition, and increased with increasing GeO₂ content. The mechanism, apparent activation energy (nQ), and apparent frequency factor (β ₀ n ) of diffusion at the initial sintering stage were estimated using the sintering-rate equations that are applicable to the CRH data. The sintering mechanism changed from grain-boundary (GBD) to volume diffusions (VD) by GeO₂ addition, and both nQ and β ₀ n of diffusion increased with increasing GeO₂ content. It is, therefore, concluded that the enhanced sintering mechanism by GeO₂ addition is explained by the GBD→VD change and increases in both nQ and β ₀ n of diffusion at the initial sintering stage.