Metallizing ceramics

Bonding ceramic material to metal is very challenging because of the differences in the thermal expansion coefficients of the two materials. Brazing is often the preferred method to establish such bonding, an effective method for creating a leak-tight and robust joint between the two materials. To braze a ceramic part it is very important that a wettable surface is created on the ceramic part. This can be done by metallization of the ceramic part.

Metallizing ceramics can be done on multiple ways and the material can be plated with various metals(Ni, Ag, Au). One of the most common way is metallisation with a Mo/Mn layer with nickel plating. The first step of this metallization is the application of a layer moly-manganese by screen printing or brush coating. The coating is fired in a wet hydrogen environment at 1450-1600 °C, leaving a “glassy” metalling coating 300-500micron thick. After this process the nickel plating can be applied. This final layer needs to fired at 850-950°C to create its metallic surface which is ready for the brazing process.

Applications:

–          High voltage insulators

–          Vacuum breaks

–          Electronic packages and connectors

–          Structural brazing