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.
Material
Properties
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.
Manufacturing
Process
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
|
