Abstract:

Microcrystalline Al₂O₃ ceramic with high purity was prepared by normal pressure sintering and high pressure sintering using superfine alumina powder.The experimental results indicated that high-speed ball milling in ethanol could reduce the average size of Al₂O₃ particles remarkably，and increase the specific surface area and sintering activity of Al₂O₃ powder.Pure Al₂O₃ ceramic with a relative density of 98.71% was fabricated under sintering pressure of 4.5 GPa and at a temperature as low as 1230℃ in 30 min.As compared with normal pressure sintering, the sintering temperature was decreased remarkably in the high pressure sintering process，the velocity of mass transfer was increased and the sintering time was shortened.High pressure sintering could achieve the effect of fast and low-temperature sintering.Because of a relatively low sintering temperature in the high pressure sintering process，liquid phase did not exist in MgO-doped Al₂O₃ ceramic and MgO had no effect on densification and restraint of Al₂O₃ grain growth.

Key words:

氧化铝, 常压烧结, 高压烧结, 氧化镁, 液相

摘要：

以高纯超细α-Al₂O₃粉为原料，采用常压、高压烧结制备了高纯Al₂O₃陶瓷。研究表明，在乙醇溶剂中高速球磨可显著降低Al₂O₃粉料的平均颗粒尺寸，提高粉料的比表面积与烧结活性；在4.5 GPa、1230℃高压烧结30 min，制备了相对密度达98.71%的无烧结助剂掺杂的Al₂O₃陶瓷；与常压烧结相比，高压烧结可显著降低烧结温度，提高传质速率，大幅度缩短烧结时间，达到快速、低温烧结的效果；由于相对较低的烧结温度，掺杂微量MgO的Al₂O₃陶瓷在高压烧结中未出现液相，MgO对烧结致密化及Al₂O₃晶粒生长抑制几乎无影响。

关键词:

氧化铝, 常压烧结, 高压烧结, 氧化镁, 液相