氮化硅浆料的胶体特性研究

Studies on the Electrokinetics of Silicon Nitride Suspensions

本文研究了Ｓｉ３Ｎ４ 浆料的胶体特性，结果表明：Ｓｉ３ Ｎ４ 悬浮粒子的等电点（ｉｓｏｅｌｅｃｔｒｉｃ ｐｏｉｎｔ，简称ＩＥＰ） 在ｐＨ＝４ ．２ 处。分散介质的离子强度影响Ｓｉ３ Ｎ４ 粒子的Ｚｅｔａ 电位。分散剂的引入有效地提高Ｓｉ３Ｎ４ 粒子的Ｚｅｔａ 电位，并引起ＩＥＰ 的位移。粉体经不同工艺的预处理后ＩＥＰ 均发生不同程度的位移。Ｘ 光电子能谱（ＸＰＳ） 分析表面组成发现其ＩＥＰ 的位移与Ｓｉ３ Ｎ４ 粉体表面的氧化程度有关。同时，对Ｓｉ３ Ｎ４ 浆料在不同条件下的分散性进行了考察，表明其分散性与胶体特性具有很好的一致性。

In this paper,the electrokinetics of Si 3N 4 suspensions is investigated.The experimental results indicate that the isoelectric point (IEP) of Si 3N 4 particulates is at the pH value of 4.2.The ionic strength of the dispersing medium has a great influence on the Zeta potential of Si 3N 4 particulates.The introduction of dispersant to Si 3N 4 suspension significantly improves the Zeta potential of Si 3N 4 particulates and shifts their IEP.The shift in the IEP is caused by various pretreatments of Si 3N 4 powders.X-ray photoelectron spectrum (XPS) of Si 3N 4 powders shows that the shift in the IEP is correlative with the oxidizing degree on the surface of Si 3N 4 powders.Acid leaching can improve the Zeta potential,and hence the dispersibility of Si 3N 4 suspensions efficiently.Moreover,the dispersibility of suspensions at various conditions is in good agreement with its electrokinetics.