IMPROVEMENT OF WETTING BEHAVIORS BETWEEN METAL AND CERAMICS BY USING INTERFACIAL SCIENCE

Wetting behaviors are an important and physical phenomena relating to various fields.Particularlv，it is important that electronic ceramics is wetted by an electrode metal in order to let the electronic ceramics perform their functions through the electrode on the electronic material.The field，however，is seemed to be s strongly based on people‘s experiences and no scientific view points，and the situations have not been changed as of today.Oxygen partial pressure is paid attention for effects of atmosphere to be reported on it.On the other hand，the requirement for non-wetting is seen sometime。Non-wetting material should be developed for the material of hopper in which melted iron flows，for instances。In microscopic field，the wetting behaviors for coating on particle by metal or ceramics is required.Based on these backgrounds，I focused on the interfaces between ceramic and metal，and considered wetting behaviors as microscopic phenomena and discussed with electronic stand points.One of methods was analysis of the interfaces by a computer simulation.The results by the simulation were related to the contact angles in experiments indicating wetting behaviors directly.(1)the surface oxygen gives and takes electrons with a metal atom placed on the ceramics in the case of oxide substrate.(2)Bond orders between metal and oxygen indicating the bonding strength presented larger values in Ag and Cu than those in the cases of Al and Sn.And the bond orders of Ti-Metal were also larger values in Ag and Sn as compared to Al and Sn.(3)In experiments，the contact angles of Ag and Cu were about90°and about130°in case of Al and Sn.As results，wetting behaviors were found to be relating to the electron transferring between a metal atom and an atom in substrate。

Wetting behaviors are an important and physical phenomena relating to various fields. Particularlv, it is important that electronic ceramics is wetted by an electrode metal in order to let the electronic ceramics perform their functions through the electrode on the electronic material. The field, however, is seemed to be s strongly based on people's experiences and no scientific view points, and the situations have not been changed as of today. Oxygen partial pressure is paid attention for effects of atmosphere to be reported on it. On the other hand, the requirement for non-wetting is seen sometime. Non- wetting material should be developed for the material of hopper in which melted iron flows, for instances. In microscopic field, the wetting behaviors for coating on particle by metal or ceramics is required.Based on these backgrounds, I focused on the interfaces between ceramic and metal , and considered wetting behaviors as microscopic phenomena and discussed with electronic stand points. One of methods was analysis of the interfaces by a computer simulation. The results by the simulation were related to the contact angles in experiments indicating wetting behaviors directly.(1) the surface oxygen gives and takes electrons with a metal atom placed on the ceramics in the case of oxide substrate.(2) Bond orders between metal and oxygen indicating the bonding strength presented larger values in Ag and Cu than those in the cases of Al and Sn. And the bond orders of Ti-Metal were also larger values in Ag and Sn as compared to Al and Sn.(3) In experiments, the contact angles of Ag and Cu were about 90゜ and about 130゜ in case of Al and Sn. As results, wetting behaviors were found to be relating to the electron transferring between a metal atom and an atom in substrate.