ANODIC BONDING BETWEEN CERAMICS AND METAL, AND ITS ANALYSIS OF BONDING MECHANISM

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Anodic bonding by lapping metal to ceramics and then applying electric al potential has grate-watched recently on the point of low-temperature bonding, Unfortunately, the effect of applied potential on the microstructure around bonded interface and the diffusion of the elements has still unknown. So that, it has unknown that the anodic bonding is suitable for the assemble technique for sensor and actuator. The aim of this study is to clarify the effect of the bonding conditions on the interfacial structure and to research the possibility for the application use. At first, in order to understand the effect of electrical potential on the atomic diffusion, metal film was evaporated on the ionic conductor and then the effect of the condition of the electrical potential on current density and microstructure were estimated. Ionic conductors used in this study were boro-silicate glass and sodium containing beta alumina Cathode side was glass and beta alumina, and Anode side was aluminum file … More side, respectively. As electrical potential with several potential patterns applied to aluminum coated ionic conductor at 523-673K, the change of electric current in aluminum coated glass and beta alumina was measured. Therefore, the electric current increased dramatically on the morrow of applying potential and show the maximum point and then decreased gradually. This phenomena is related with the mobility of sodium ion in ionic conductor quantitatively. As increasing treatment temperature, movable ions increased. But the increment of current density obtund as increasing temperature. From result of EPMA analysis and TEM observation, the content of sodium element decreased as approaching bonded interface, which is sodium depletion layer. This layer shows malignancy for use the sensor. Furthermore, aluminum element diffused in sodium depletion layer. As the sodium contents in glass are more than that in beta aluminum, the total current and the movement of sodium ion in beta aluminum is more than that of glass. Less