关键词: 低温燃烧, MgAl₂O₄粉体, MgAl₂O₄多孔陶瓷, 显气孔率, 显微结构

Abstract: To lower the synthesis temperature of MgAl₂O₄ and the energy consumption,MgAl₂O₄ powders were synthesized via a low-temperature combustion route using Al(NO₃)₃·9H₂O,Mg(NO₃)₂·6H₂O and NH₄NO₃ as oxidizing agents,C₂H₅NO₂ and CH₄N₂O as reducing agents,and EDTA as the fuel.Then porous MgAl₂O₄ ceramics were prepared with the prepared powders or the prepared powders treated at 800 ℃.The effects of the EDTA addition (0,2.5%,5%,7.5% of the reducing agents,by mole) on the properties of the MgAl₂O₄ powders and the porous MgAl₂O₄ ceramics were studied.The experimental results show that:(1)with the increase of the EDTA addition in the precursors,the ignition loss increases and the specific surface area of the MgAl₂O₄ powders rises significantly;(2) with the increase of the EDTA addition in the precursors,the water absorption and the apparent porosity of the porous MgAl₂O₄ ceramics obviously decrease,the bulk density increases significantly,and the grain size of MgAl₂O₄ decreases slightly;(3)compared with the ceramics prepared from the MgAl₂O₄ powders treated at 800 ℃,the porous MgAl₂O₄ ceramics prepared with the MgAl₂O₄ powders have relatively higher water absorption and apparent porosity,and more uniform microstructure;(4)when the EDTA addition is 2.5% of the reducing agents,the porous ceramic sample prepared with the MgAl₂O₄ powders has the water absorption of 23.8%,the apparent porosity of 46.9%,and the bulk density of 1.9 g·cm^-3,presenting uniform microstructure.

Key words: low-temperature combustion, MgAl₂O₄ powder, porous MgAl₂O₄ ceramics, apparent porosity, microstructure