为研究不同烧结方法制备致密细晶氧化铝陶瓷的机理，以0.20 μm Al₂O₃为原材料，采用常规高温常压烧结、高压成型常压烧结和高温高压烧结方法来制备Al₂O₃陶瓷。通过X射线衍射、扫描电镜、密度和维氏硬度的测试对得到的Al₂O₃陶瓷的晶体结构、微观形貌和性能进行了分析和表征，并对高压成型常压烧结和高温高压烧结的烧结机理进行了探讨。结果表明：3种烧结方法都可以得到致密的Al₂O₃陶瓷，样品的相对密度分别为96.64%、97.12%和97.87%。在5 GPa压力下成型，Al₂O₃陶瓷素坯的相对密度达60.02%。高压能使氧化铝颗粒迅速靠拢，塑性滑移加快，晶粒间小气孔消除，扩散加强，促进致密化，在较低的温度下（1 000 ℃）烧结得到Al₂O₃陶瓷的晶粒尺寸只有0.22 μm，稍大于原始Al₂O₃粉体的晶粒尺寸，且晶粒大小均匀。在高温高压烧结中，外加压力能增加烧结的驱动力，在低温短时下能得到致密的样品。由于高压成型常压烧结的样品晶粒尺寸最小，使样品有最大的维氏硬度，其值为1 835。

To investigate the mechanism of preparing dense fine-grained alumina ceramics using different sintering methods，Al₂O₃ ceramics were prepared using conventional high-temperature and atmospheric pressure sintering，high-pressure forming and atmospheric pressure sintering，and high-temperature and high-pressure sintering methods with 0.20 μm Al₂O₃ as the raw materials.The crystal structure，microstructure，and properties of the obtained Al₂O₃ ceramics were analyzed and characterized by X-ray diffraction，scanning electron microscopy，density，and Vickers hardness tests.The sintering mechanisms of high-pressure forming，atmospheric pressure sintering，and high-temperature high-pressure sintering were also explored.The results showed that dense Al₂O₃ ceramics could be obtained by all three sintering methods，and the relative densities of the samples were 96.64%，97.12% and 97.87%，respectively.Due to forming under a pressure of 5 GPa，the relative density of Al₂O₃ ceramic green body reached 60.02%.High pressure could make Al₂O₃ particles move closer quickly，accelerate plastic slip，eliminate small pores between grains，strengthen diffusion，and promote densification.Al₂O₃ ceramic with a grain size of only 0.22 μm was obtained after sintering at a lower temperature（1 000 ℃），which was slightly larger than the grain size of the raw Al₂O₃ powder，and the grain size was uniform.In high temperature and high pressure sintering，applied pressure could increase the driving force of sintering，and dense samples could be obtained at low temperatures for a short time.Since the grain size of the samples formed at high pressure and sintered at normal pressure was the smallest，the samples showed the largest Vickers hardness，which was 1 835.