Preparation and Properties of Sintering Additives Coated Si3N4 from Heterogeneous Nucleation Process

• 作 者: Juxian ZHANG Jinjun FENG Longg
• 机 构: Beijing Vacuum Electronics Research Institute
• 出 处: 材料科学技术学报
• 发表日期: 2004年期
• 关键词: Si3N4 powder Sintering additives Zeta potential Rheological property

The sintering additives such as Al2O3 and/or Y2O3 were coated on the surfaces of Si3N4 particles via heterogeneousnucleation processing using a buffered pH solution as the precipitation reagent. They nucleated and grew only onthe surfaces of Si3N4 and did not form sol particles in solution by TEM observation. The isoelectric point (IEP) ofcoated Si3N4 was different from that of as-received Si3N4. The IEP of Al(OH)3-coated Si3N4 occurred at pH8.4,which is close to that of alumina. When Al(OH)3-coated Si3N4 particles were coated with Y(OH)3, the IEP of coatedSi3N4 powder shifted from pH8.4 to pH9.2, similar to that of yttria. In addition, the rheological data showed thatAl2O3 and/or Y2O3 coated Si3N4 suspension is nearly Newtonian and that added Si3N4 suspension shows a shearrate thinning behavior.