二次尖晶石化反应对MA-Al_2O_3材料烧结的影响

Effect of secondary spinelization reaction on sintering of MA-Al_2O_3 materials

将w(Al2O3)为71%、78%和85%的3种不同组成的镁铝尖晶石细粉(粒度均≤0.074 mm)分别与α-Al2O3微粉混合,采用半干法压制成50 mm×50 mm的MA-Al2O3质试样,干燥后,分别在1 300～1 650℃保温4 h煅烧,随炉冷却后测量试样煅烧后的线变化率、显气孔率、体积密度和物相组成。结果表明:镁铝尖晶石原料的富铝程度越高,MA-Al2O3材料的可烧结性越差,其二次尖晶石化反应需在更高的温度区间完成,反应伴随的膨胀效应对MA-Al2O3材料烧结的限制作用也更为突出。

The MA-Al2O3 specimens with the size of φ50 mm × 50 mm were prepared by mixing the fines of magnesium aluminate spinel （the mass percent of Al2O3 was 71% ,78%, and 85%, respectively; grain size ≤0. 074 mm） and micropower of α-Al2O3,semi-dry pressing,drying,firing at different temperatures for 4 h （1 300- 1 650 ℃）, and cooling. The linear change rate, apparent porosity, bulk density and phase compositions were determined. The results show that the higher aluminum-rich degree of magnesium aluminate decrea- ses the sinterability of MA-Al2O3 specimens, the secondary spinelization reaction need to complete at higher temperatures,and the occurred expansion effect plays more obvious hindering role in MA-Al2O3 materials sintering.