Al2O3 powders with four different particle sizes were densified using a spark plasma sintering (SPS) apparatus under three different sintering conditions: holding time, heating rate, and mechanical pressure. The Al2O3 powder compact sintered at a higher heating rate produced a sample with a higher density and a fine-grained microstructure, while abnormal grain growth and a lower density resulted when a lower heating rate was applied, though the sintering temperature and holding time were the same in both cases. This revealed that rapid sintering by SPS was effective for promoting the densification of the powder. However, the powder with a coarse particle size was hard to sinter at a higher heating rate. Microstructural observation revealed that the edge part was denser than the inside of the sample when the holding time was short. Increasing the holding time made it possible for the inside to be sintered almost as dense as the edge part. Mechanical pressure was found to enhance densification of the Al2O3 powder. On the basis of these results, the SPS process is discussed.
在三种不同的烧结条件(保温时间、加热速率和机械压力)下,使用火花等离子烧结(SPS)设备对四种不同粒度的 Al2O3 粉末进行了致密化处理。在烧结温度和保温时间相同的情况下,采用较高加热速率烧结的 Al2O3 粉末致密材料样品具有较高的密度和较细的微观结构,而采用较低加热速率则会导致晶粒异常长大和密度降低。这表明利用 SPS 快速烧结能有效促进粉末致密化。然而,粒度较粗的粉末很难在较高的加热速率下烧结。微观结构观察表明,当保温时间较短时,样品边缘部分的密度高于内部。延长保温时间后,内部的烧结密度几乎与边缘部分相同。机械压力可提高 Al2O3 粉末的致密性。在这些结果的基础上,对 SPS 工艺进行了讨论。