稻壳加入量对氧化铝多孔材料的性能及结构的影响

Effect of rice husk on structure and properties of alumina porous ceramics

为了研究稻壳造孔剂对氧化铝多孔材料性能的影响,以粒度≤0.074和≤0.045 mm的板状刚玉粉、d50=2μm的α-Al_2O_3微粉、d50=5μm的ρ-Al_2O_3微粉和粒度≤0.045 mm的金属铝粉为主要原料,通过添加不同量的稻壳(≤0.045 mm质量分数分别为0、5%、10%、15%、20%、25%和30%)为造孔剂,分别在1 450、1 500、1 550和1 600℃保温3 h烧后制备了氧化铝质多孔材料。对烧后的试样进行了体积密度、显气孔率、热导率和高温力学性能的检测,采用XRD进行了物相组成分析,借助扫描电镜对烧后试样的显微结构和孔结构进行了分析表征。结果表明:稻壳的添加会对氧化铝多孔材料的孔结构、热导率以及力学性能产生显著影响。随着稻壳添加量的增加,试样的显气孔率和平均孔径逐渐增大,相应的热导率逐渐减小。但由于稻壳烧失后残留下的Na_2O以及K_2O等杂质在高温下会形成液相,这也导致了材料高温抗折强度和荷重软化温度显著降低。

Alumina porous ceramics were successfully fabricated using tabular alumina （≤0. 074 and ≤ 0.045 mm）, a-AI=O3 micropowder （ dso = 2 μm）, 9-AI203 micropowder （ d50= 5 μm）, and metal aluminum powder （≤0.045 mm） as the starting materials,adding different amounts of rice husk （0,5% ,10% ,15%, 20% ,25% and 30% ,by mass） as the pore-forming agent,and firing at 1 450,1 500,1 550 and 1 600 ℃ re- spectively for 3 h to research the effect of rice husk pore-forming agent on properties of alumina porous ce- ramics. The bulk density, apparent porosity, thermal conductivity and thermal-mechanical properties of fired specimens were determined. The phase composition was analyzed by XRD. The microstructure and pore structure of the fired specimens were investigated by scanning electron microscopy （SEM）. The results show that the introduction of rice husk has a great influence on the pore structure,thermal conductivity and mechanical properties of the alumina porous ceramics. With the increase of the rice husk amount, the ap- parent porosity and average pore size of the specimens increase,whereas the thermal conductivity decrea- ses. The residual Na20 from the ignition of rice husk and the impurities like K20 form liquid phases at high temperatures, decreasing the hot modulus of rupture and refractoriness under load obviously.