MACOR® Machinable Glass Ceramic
High use temperature
Excellent electrical insulator
Excellent thermal insulator
machinable glass ceramic gives you the characteristics you need from
a ceramic with the added benefit of easy fabrication using ordinary
machine tools. No longer is it necessary to staff a ceramic
specialist with high temperature kilns or specialized diamond
grinding equipment. Fabrication is quick, inexpensive and accurate
using your in-house personnel, local machinist or Accuratus.
is melted and cast using conventional glass making techniques. It is
a fluorine rich glass with a composition approaching trisilicic
fluorphlogopite mica (KMg3AlSi3O10F2).
Upon cooling from the melt, the glass spontaneously phase separates
into fluorine rich droplets. The resulting glass has the appearance
of an opal glass. Subsequent controlled heat treatment devitrifies
the fluorine rich droplets causing a series of morphological changes
ultimately resulting in the formation of randomly oriented,
interlocked, sheet-like fluorphlogopite mica crystals within the
alumino-borosilicate glass matrix. The volume percent crystalline
phase after heat treatment is approximately 55% with a mean crystal
size of 20 microns. It is this uniform distribution of randomly
oriented mica within the parent glass that gives rise to the unique
characteristics of MACOR®.
possesses a number of notable physical
It has a continuous use temperature of 800°C. Its coefficient of
thermal expansion readily matches most metals and sealing glasses.
It is nonwetting, exhibits zero porosity, and unlike ductile
materials, won’t deform. It is an excellent insulator at high
voltages, various frequencies and high temperatures. When properly
baked out, will not outgas in vacuum environments.
tolerances are surprisingly tight, up to 10 microns (.0005”). It can
be machined to a surface finish of less than 0.5 micron (20
microinch) and polished to a smoothness of 125 angstroms (0.5
microinch) average roughness. Most conventional
machining processes can be used. Configurations are limited only
by available equipment and the experience of the machinist.
MACOR® Sealing, Joining, Metallizing
Macor can also be joined or sealed to itself and other materials in
a number of ways: metallized parts can be soldered together and
brazing has proven an effective method of joining the material
to various metals; epoxy produces a
strong joint, and sealing glass
creates a vacuum tight seal. Even a straightforward mechanical joint
is possible. It can be thick film
metallized using inks or thin film
coated using sputtering techniques.
The Bottom Line with MACOR®
When you need
the performance of a technical ceramic — high use temperature,
electrical resistivity, zero porosity — and your application demands
the ready fabrication of a complicated shape — quickly, precisely,
privately — consider MACOR®. It will lower costs and
substantially reduce the time between design and actual use.
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