Study Of Nickel Composite Powder And The Corresponding Electrode For Multilayer Ceramic Components

Multilayer electronic components have been widely used due to a series of virtues such as small size, high performance and suitable for surface mounting. Among them,thermistors and varistors are often used simultaneously as circuit protection components,so it would have practical significance manufacturing thermistor/varistor bifunctional multilayer devices. Inner electrodes are important parts of thermistor/varistor bifunctional multilayer devices and it will reduce costs greatly when using Ni inner electrodes. But there are three main difficulties in applying Ni as inner electrodes. Firstly,Ni has a low oxidation resistance temperature. Secondly, the shrinkage behaviors of Ni and dielectric do not match. Thirdly, there may be interdiffusion and reaction in the interface of Ni electrodes and ceramic layers, which may deteriorate components' properties.In this paper, the surface of Ni particles is modified by chemical synthesis of Ni/BaTiO3 and Ni/ZnO composites in which the constituents are homogeneously mixed and Ni particles are coated with BaTiO3 or ZnO. The composites have a higher oxidation resistance temperature, and because the added constituent is the main element of the dielectric layer, it won't affect the dielectric's properties; in addition, it may improve the shrinkage match between electrodes and dielectric layers. The as-prepared composites are used as the conductive phase of inner electrode pastes.Firstly, Ni/BaTiO3 and Ni/ZnO composites are synthesized by hydrothermal precipitation and hydrothermal crystallization respectively. And the reaction conditions which would affect the constituents or structures of the composites like the pretreatment of Ni, the dose of hydrolyzing regulators, are investigated. Finally, the composites with pure phases, higher oxidation resistance and improved shrinkage behavior are achieved.Then, prepare the corresponding electrode pastes. Investigate the prepared pastes' properties such as conduction and sintering behavior, and apply the pastes to dielectric to study the co-fire behaviors with dielectric layers. The as-prepared pastes can be sintered to conductive films and the conduction meets the requirements as inner electrodes for multilayer thermistor or varistor. The paste prepared with Ni/BaTiO3 composite shows great shrinkage match with dielectric, and the sintered inner electrodes have a close connection with the dielectric layers and no defects are found.