添加不同 Al2 O3对蓝晶石基微孔莫来石陶瓷相组成、显微结构与性能的影响

摘要

The microporous mullite ceramics were prepared by grouting and reaction sintering at 1 500 ℃ for 3 h using kyanite as the main starting material and Al(OH)3 ,γ-Al 2 O3 ,ρ-Al 2 O3 or α-Al 2 O3 as the supplemen-tary material respectively.The effects of Al(OH)3 ,γ-Al 2 O3 ,ρ-Al 2 O3 and α-Al 2 O3 on the phase composition, microstructure,cold physical properties and pore size distribution of the ceramics were investigated.The results show that the mullite content in specimens is reduced in sequence adding Al (OH)3 ,γ-Al 2 O3 ,ρ-Al 2 O3 and α-Al 2 O3 ,the mullite grains change from needle-like into stumpy and the glassy phase content increases gradually;the bulk density and apparent porosity of specimens have no obvious differences and the specimen with α-Al 2 O3 has the highest bulk density and the lowest apparent porosity;all the fired speci-mens expand and the expansion sequence is the specimens with Al(OH)3 or γ-Al 2 O3 >the specimen withα-Al 2 O3 >the specimen with ρ-Al 2 O3 .Owing to the toughening and strengthening effects of needle-like mul-lite,specimens with Al(OH)3 ,γ-Al 2 O3 or ρ-Al 2 O3 present high strength while the specimen with α-Al 2 O3 has less mullite formed and the formed mullite is mainly stumpy so it behaves a low strength;owing to the filling and dividing effects of needle-like mullite for pores,the average pore size of the four groups of specimens increases in sequence.I n summary,Al(OH)3 and γ-Al 2 O3 are suitable supplementary materials for prepar-ing microporous mullite ceramics.%以蓝晶石为主要原料，Al（OH）3和γ、ρ、α三种不同晶型的 Al2 O3为辅料，采用注浆成型并于1500℃保温3 h 反应烧结制备微孔莫来石陶瓷材料，研究了 Al（OH）3、γ-Al2 O3、ρ-Al2 O3和α-Al2 O3对蓝晶石基微孔莫来石陶瓷材料的物相组成、显微结构、常温性能和孔径分布的影响。结果表明：分别加入 Al（OH）3、γ-Al2 O3、ρ-Al2 O3或α-Al2 O3，烧后试样中莫来石的生成量依次减少，其形貌逐渐由细长针状变为短柱状，玻璃相含量逐渐增多。试样的体积密度和显气孔率相差不大，而以添加α-Al2 O3试样的体积密度最高、显气孔率最低。烧后试样均产生膨胀，其中加入 Al（OH）3或γ-Al2 O3试样的线膨胀率最大，加入α-Al2 O3试样的次之，加入ρ-Al2 O3试样的最小。针状莫来石对试样具有强韧化作用，使得加入 Al（OH）3、γ-Al2 O3或ρ-Al2 O3的试样具有较高强度，而加入α-Al2 O3的试样中莫来石生成量较少，且形貌多为短柱状，导致其强度相对较低。且针状莫来石对气孔填充与分割的作用逐渐减弱，使得四组试样的平均孔径依次增大。因此，当以 Al（OH）3或γ-Al2 O3为辅料时，适于制备微孔莫来石陶瓷材料。