Y_2O_3－ZrO_2超微粉体烧结初期动力学研究

On Mechanism Underlying Sintering Densification of Y_2O_3- ZrO_2 Nanometer Powders

对Ｙ２Ｏ３－ＺｒＯ２纳米级超微粉体烧结过程和烧结动力学进行了研究，提出了超微粉体烧结初期致密化机理。针对超微粉体的高烧结活性，从上述两方面对超微粉体和普通粉体烧结过程进行了分析和讨论。

We found that using nanometer Y2O3- ZrO2 powders instead of microsized ones to prepare functional ceramics can greatly raise their electrical conductivity at much lower sintering temperature. We now report on our experimental findings concerning the mechanism underlying improved electrical conductivity.We find that, in addition to the well known surface diffusion, rearrangement of primary particles is also a main factor contributing to sintering densification, which is directly responsible for high electrical conductivity.We find that sintering densification occurs mainly during the first stage of sintering at 1 200℃, 18sting 2￣3 minutes. In this stage, surface diffusion causes primary particles to be compacted through rearrangement; as a beneficial result, only very small pores are left as shown in Fig. 4, which is a TEM picture ; in this stage the liner shrink ratio △L/Lo is proportional to time of sintering. In the second stage of sintering, lasting several tens of minutes or more, densifying proceeds slowly as a result of the well known surf see diffusion and △L/L0 is commonly known to be proportional to the cube root of time of sintering.