低温烧成高纯Al_2O_3多孔陶瓷膜支撑体的制备

为了降低高纯Al2O3(α-Al2O3质量含量≥99%)多孔陶瓷膜支撑体烧成温度,以粒径为30μm的α-Al2O3为原料,分别添加TiO2和TiO2/Cu(NO3)2为烧结助剂,通过干压成型和挤出成型制备片状和管式多孔支撑体。Al2O3-TiO2和Al2O3-TiO2-CuO体系分别在高温下出现的液相低共熔物促进了多孔支撑体的烧结。当氧化铝支撑体中添加0.5%(摩尔分数,下同)TiO2+0.5%Cu(NO3)2后,在1600℃的烧成即可获得机械性能高、渗透性能好和耐酸碱腐蚀性能优异的管式支撑体。在压力为0.1MPa时,支撑体的水渗透通量为12.1m3/(m2·h),弯曲强度为44.5MPa。经过80℃,含10%(质量分数,下同)HNO3的溶液腐蚀800h及80℃,含10%NaOH的溶液1200h后,支撑体的质量损失率分别为1%和0.35%。

PREPARATION OF HIGH PURITY ALUMINA MACROPOROUS SUPPORT AT LOW SINTERING TEMPERATURE

In order to reduce the sintering temperature of pure alumina membrane support, disk and tubular macroporous ceramic supports consisting of alumina, using TiO_2 or TiO_2/Cu(NO_3)_2 as sintering promoter agents, were prepared by dry-pressing and plastic extrusion respectively. The appearance of the liquid eutectic mixture during the sintering process of Al2O3-TiO_2 and Al_2O_3-CuO- TiO_2 system is helpful to increase the sintering rate of macroporous alumina supports, which prepared at a sintering temperature below 1 700 ℃ exhibit both high mechanical strength and high permeability. In the case of the support with a composition of 99%Al2O3, 0.5% (in mole, the same below) TiO_2 and 0.5% Cu(NO_3)_2, a support with combination of high permeability, comparative high mechanical strength as well as excellent corrosion-resistant property can be prepared by sintering at 1 600 ℃, which is lower than that for the pure alumina macroporous support. The properties of this kind of support sintered at 1 600 ℃ are as follows: its pure water flux at 0.1 MPa and the three-point bending strength are 12.1 m~3/(m~2·h) and 44.5 MPa, respectively. When immersed in 10% (mass fraction, the same below) HNO_3 (80 ℃ for 800 h) or 10% NaOH (80 ℃ for 1 200 h), the mass losses of such support are 1.0% and 0.35%, respectively, which indicates it has an excellent corrosion-resistant properties towards hot HNO_3 and NaOH.