高纯超细氧化铝粉的常压烧结与高压烧结

Normal pressure sintering and high pressure sintering of superfine Al_2O_3 powder with high purity

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4.5GPa、1230℃高压烧结30min,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。

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.