冷冻干燥法制备高气孔率、低介电的Si3N4陶瓷  

Research on Si3N4 with High Porosity and Low Dielectric Fabricated by Freeze-drying Method

作　　者：孙肖坤 孙孟勇 刘小冲 赵娟 SUN Xiaokun;SUN Mengyong;LIU Xiaochong;ZHAO Juan(National Key Laboratory of Thermostructure Composite Materials,School of Materials Science and Engineering,Northwestern Polytechnical University,Xi’an 710072,China)

机构地区：[1]西北工业大学材料学院超高温结构复合材料国家重点实验室

出　　处：《材料导报》2020年第4期25-31,共7页Materials Reports

基　　金：中国博士后科学基金(2015M570853);陕西省自然科学基础研究计划(2017JM5119)~~

摘　　要：采用冷冻干燥法制备具有低介电、定向双峰孔径分布的多孔Si 3N 4陶瓷,并利用Zeta电位、流变仪研究分散剂种类、含量及pH值对浆料的影响。结果表明:当分散剂为聚丙烯酸铵(NH 4-PAA)且其含量为0.8%(质量分数),浆料pH值在10左右时浆料的分散效果最好。利用压汞仪、XRD、SEM与矢量网络分析仪研究了粘结剂含量与固相含量对多孔陶瓷微观结构与性能的影响。结果表明:随着粘结剂含量与固相含量的增加,陶瓷的气孔率下降,力学性能增强。当固相含量由15%(体积分数)增加至40%(体积分数)时,气孔率由82.9%降低至40.6%,抗弯强度由(1.2±0.2)MPa增加到(94.7±5)MPa,抗压强度由(2.1±0.5)MPa增加到(314±8)MPa,介电常数由1.5增加至3.7(12.4~18 GHz波段内)。通过冷冻干燥法制备的多孔Si 3N 4陶瓷在过滤、催化剂载体、透波材料等领域具有更广阔的应用。Aporous Si 3N 4 with low dielectric,directional bimodal pore size distribution was prepared by freeze-drying method,and Zeta potential,rheo-meter were used to study the effect of dispersant type,content and pH value on slurry.The results show that when the pH value is around 10,using NH 4-PAA as dispersing agent with the content of 0.8wt%,the slurry has the best dispersing effect.The effects of binder content and solid phase content on the microstructure and properties of porous ceramics were studied by mercury injection apparatus,XRD,SEM and vector network analyzer.The results showed that with the increase of binder content and solid phase content,the porosity of ceramics decreased and the mechanical properties enhanced.When the solid content increased from 15vol%to 40vol%,porosity declined from 82.9%to 40.6%,the bending strength increased from(1.2±0.2)MPa to(94.7±5)MPa,the compressive strength increased from(2.1±0.5)MPa to(314±8)MPa,the dielectric constant within 2.4 GHz to 18 GHz band increased from 1.5 to 3.7.Porous Si 3N 4 ceramics prepared by freeze-drying methods have broader application in the fields of filtration,catalyst carrier and wave-transparent materials.

关 键 词：冷冻干燥法 多孔Si 3N 4陶瓷 低介电 高气孔率 

分 类 号：TQ174[化学工程—陶瓷工业]