INTERFACIALLY ACTIVE METALS IN METAL-CERAMIC COMPOSITES

The role of the interface in metal-oxide composite materials has been investigated to determine the nature of bonding where an interfacially active metal has been used to promote wetting. A model system of Ag-MgO was used with titanium as the wetting agent. Electron diffraction was used to identify the magnesium titanate structure at the surface of the MgO crystal and the titanium oxides found in the adjacent titanium layer. Infiltration of the titanium oxide-magnesium titanate interface with liquid silver results in a separation of the solid oxide surfaces and the wetting and spreading of silver on the titanate surface. It is shown that the change in structure of the MgO surface must be taken into account when assessing the wetting phenomenon whenever an interfacially active metal is employed.