分散剂聚乙二醇对Si3N4纳米粉末分散性的影响

纳米相颗粒弥散在陶瓷基体中构成的陶瓷刀具材料具有优异的力学性能,制备这类复合材料的体的均匀混合.基于此,研究了制备Si3N4基陶瓷刀具材料所用纳米Si3N4粉末分散性与悬浮液pH值、分散剂聚乙二醇(polyethylene glycol,PEG)分子量及用量之间的关系.为得到分散良好、抗团聚的纳米Si3N4悬浮液,用PEG作为分散剂,测定了电位与pH值关系,进行了沉降实验.结果表明:所采用Si3N4纳米粉末等电位点在pH=5.5附近,最佳分散条件为PEG相对分子量为4 000,分散剂质量含量为0.5%及分散介质pH值在9.5～10之间.

EFFECT OF POLYETHYLENE GLYCOL SURFACTANT ON THE DISPERSION OF Si3N4 NANO-POWDER

Ceramic tool materials,in which the nanometer particles are fully dispersed,have excellent mechanical properties.The key step in preparing these materials is the full dispersion of the nanometer particles and their homogeneous mixing with the matrix mate- dais.The influences of pH value,the molecular mass and addition amount of polyethylene glycol (PEG) surfactant on aqueous nano-Si3N4 aqueous suspension were investigated.In order to prepare a stable,well dispersed aqueous nano-Si3N4 suspension,the surface of the Si_3N_4 particles was selectively absorbed with long organic molecular chains by soaking in a solution of PEG with dif- ferent molecular mass.The measurements of zeta potential and sedimentation of the suspension were carried out.The results show that the isoelectric point of Si_3N_4 nanoparticles is at a pH value of 5.5.The dispersion effect of PEG is mainly influenced by the rela- tive molecular mass,the surfactant mass content,and the pH value of the dispersion medium.As a consequence,the optimum condi- tions for nano-Si_3N_4 dispersion were a PEG molecular mass of 4 000,pH 9.5-10 with 0.5% PEG addition.