不同氧化铝源对富镁尖晶石烧结行为的影响

Effect of Different Alumina Sources on Sintering Behavior of Magnesia-Rich Spinel

以富镁尖晶石细粉为主要原料,分别添加活性氧化铝微粉、可水合氧化铝ρ-Al_2O_3、分析纯Al(OH)_3、工业氧化铝四种氧化铝源,在1 550~1 700℃烧结制备镁铝尖晶石;研究了氧化铝源对富镁尖晶石烧结行为的影响,并分析了镁铝尖晶石的物相组成及显微结构。结果表明:不同种类氧化铝源对富镁尖晶石烧结行为的影响差别较大,活性氧化铝微粉的加入能显著促进其烧结致密化,ρ-Al_2O_3、Al(OH)_3和工业氧化铝的加入则不利于其烧结致密化;在低于1 650℃烧结时,主要是游离氧化镁与氧化铝反应形成镁铝尖晶石,高于1 650℃烧结时,则有少量氧化铝固溶到尖晶石晶格中;加入活性氧化铝微粉的富镁尖晶石经1 700℃烧结3h后,得到的镁铝尖晶石晶体发育较为完善,结构致密。

With the magnesia-rich spinel as the main raw material, adding four alumina sources of activated alumina, ρ-Al2O3, Al（OH）3, industrial alumina, respectively, the magnesium aluminate spinel was prepared after sintering at temperatures of 1 550-1 700℃. The effect of alumina source on the sintering behavior of the magnesia-rich spinel was studied, and the phase composition and microstructure of the magnesium aluminate spinel were analyzed. The results show that the effects of different alumina sources on the sintering behavior of magnesia-rich spinel were different. The addition of activated alumina was in favor of the sintering densification, while with the addition of ρ-Al2O3, Al（OH）3 and industrial alumina, the influence was unfavorable. When sintering at the temperature under 1 650℃, the synthetic magnesium aluminate spinel was mainly fabricated by the reaction of free magnesia and alumina, while a little alumina was solid solved in the spinel lattice at the temperature over 1 650℃. After sintering the magnesia-rich spinel with activated alumina at 1 700℃ for 3 h, the obtained magnesium aluminate spinel had a good grain growth and a dense structure.