Metallized Ceramics for Electrical Components
ZG supplies custom Metalized Alumina Ceramics. These metallized
ceramics are ideal for use within high vacuum, high voltage and
high pressure applications.
We provide metallized ceramic for power grid tubes, vacuum
interrupters, RF windows, metallized rings and components for
insulators and sensors.
Alumina is one of the most commonly used engineering ceramic
materials, offering high hardness and wear resistance with
excellent electrical insulation properties. ZG high-purity alumina
94-96% ceramics (Al2O3) are used as a ceramic base material. Other
ceramic base materials can be use on request.
Common metalized alumina ceramics consist Molybdenum based paints
followed by nickel plating. A coating of molybdenum and manganese
particles mixed with glass additives and volatile carriers is
applied to the ceramic surface to be brazed. The application of the
coating may be hand-painted, sprayed, or robotically applied. After
air drying, the coating is fired in a wet hydrogen environment at
1450°–1600°C leaving a “glassy” metallic coating 300–500
micro-inches (7.6–12.7 microns) thick, to ensure high bond strength
between the metallized layer and the ceramic base.
The fired coating is subsequently plated with a 0.001–0.003 in.
(25.4–76.2 microns) layer of nickel. The nickel plating is
sinter-fired at 850–950°C in a dry hydrogen atmosphere leaving a
finished metallic surface that can be readily brazed using standard
braze filler metals.
Advantages of ceramics
- Low dielectric loss-the dielectric constant.
- High thermal conductivity
- Thermal expansion coefficient-the thermal expansion coefficients of
ceramics and metals are close
- High bonding strength-high bonding strength between metal layer and
ceramic
- High operating temperature-ceramics can withstand high and
low-temperature cycles with large fluctuations, and can even
operate normally at high temperatures of 500-600 degrees.
- High electrical insulation the ceramic material itself is an
insulating material and can withstand a high breakdown voltage.
Technical specifications
| Tensile Strength, Kovar Cup Method | > 20,000 psi, avg. (138N/mm2) |
| Helium Leak Rate | < 10-9 cc/sec |
| Thermal Shock Resistance room temperature to 850C | will not burst or leak after five operations |
