纳米增韧NiFe2O4陶瓷惰性阳极烧结行为与性能的研究

采用粉末冶金法制备NiFe₂O₄纳米粉增韧NiFe₂O₄陶瓷铝电解惰性阳极, 研究了NiFe₂O₄纳米粉添加量对NiFe₂O₄陶瓷惰性阳极烧结行为和材料性能的影响。通过线收缩和SEM对NiFe₂O₄陶瓷的烧结性能和显微结果进行分析。研究结果表明: 随着NiFe₂O₄纳米粉添加量的增加, 烧结收缩程度逐渐增大, 烧结致密化开始温度和烧结初期活化能逐渐降低, 添加量为40%时试样从900℃开始大幅度收缩, 烧结初期表观活化能下降到291.43 kJ/mol。NiFe₂O₄陶瓷惰性阳极的体积密度、抗弯强度和断裂韧性随NiFe₂O₄纳米粉添加量的增加均呈现先上升后下降的变化趋势, 气孔率和静态腐蚀率呈先下降后上升的趋势, 均在30%达到极值, 断裂韧性达到最大值3.12 MPa•m^1/2, 是未添加纳米粉试样的2.14倍。NiFe₂O₄纳米粉的添加能够明显增强晶界结合强度, 降低陶瓷材料气孔率, 从而提高断裂表面能实现增韧作用。

Sintering Behavior and Properties of NiFe2O4 Ceramic Inert Anode Toughened by Adding NiFe2O4 Nanopowder

NiFe₂O₄ ceramic inert anode for aluminum electrolysis, strengthened by adding NiFe₂O₄ nanopowder, was prepared via powder metallurgy method. The effects of NiFe₂O₄ nanopowder content on sintering behavior and properties of NiFe₂O₄ ceramic inert anode were studied. Linear shrinkage and scanning electron microscope (SEM) were employed to characterize the sintering property and microstructure. The results show that the sintering shrinkage degree increases gradually as increase of NiFe₂O₄ nanopowder content, while the sintering temperature and apparent activation energy of initial stage of sintering decrease. When nanopowder content is 40%, the sharp sintering shrinkage begins from 900℃ and the apparent activation energy of initial stage of sintering drops to 291.43 kJ/mol. Volume density, bending strength and fracture toughness are enhanced firstly and then decreased with the increase of nanopowder content, while the porosity and static corrosion rate display opposite tendency. The maximum value of fracture toughness is 3.12 MPa•m^1/2 with nanopowder content of 30%, which is 2.14 times that of without adding nanopowder. The toughening effect is realized by the elevated fracture surface energy, which is attributed to the enhanced grain boundary cohesive bond and the reduced porosity with addition of NiFe₂O₄ nanopowder.