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Topics Covered
Features of Macor Machinable Glass
Ceramics
Properties of Macor Machinable
Glass Ceramics
Machining of Macor
Machinable Glass Ceramics
Sealing,
Joining and Metalising of Macor Machinable Glass Ceramics
Applications of Macor Machinable Glass Ceramics
Ultra-High Vacuum
Environments
Constant Vacuum
Applications
Aerospace
Industry
Nuclear-Related
Experiments
Welding Nozzles
Fixtures
Medical Equipment
Conclusion
Features of Macor
Machinable Glass Ceramics
Features of Macor machinable
glass ceramics include:
- Machinable with ordinary metalworking tools
- Macor
allows fast turnaround, no post firing required
- Holds tight tolerances, up to 0.0005in. (0.013mm)
- Withstands high temperature, up to 1000°C (no load)
- Macor
is clean, no out gasing and zero porosity.
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Properties of Macor
Machinable Glass Ceramics
Macor (machinable glass ceramic) has a continuous use
temperature of 800°C and a peak temperature of 1000°C. Its coefficient of
thermal expansion readily matches most metals and sealing glasses. Macor is
non-wetting, exhibits zero porosity, and unlike ductile materials, won’t deform.
It is an excellent insulator at high voltages, various frequencies and high
temperatures. And, when properly baked out, Macor won’t
outgas in vacuum environments.
Machining of Macor
Machinable Glass Ceramics
Machining tolerances are surprisingly tight, up to 0.0005in.
(0.013mm). Macor MGC can be machined to a surface finish of less than
20µin. (0.5µn) and polished to a smoothness of 0.5µin. (0.013µm). Configurations
are limited only by available equipment and the experience of the machinist.
Sealing, Joining and Metalising of Macor
Machinable Glass Ceramics
Macor can also be joined or sealed-both to itself and to other
materials-in a number of ways; metalised parts can be soldered together and
brazing has proved to be effective method of joining the material to various
metals: epoxy produces a strong joint, and sealing glass create a vacuum tight
seal. Even a straight forward mechanical joint is possible. Macor can be
thick film metalised using metal inks, or thin film metalised by sputtering. An
example of vapour disposition metalising is shown on the examples page. Metal
coatings available are Gold, Silver, Copper, Nickel, Platinum, Chrome and
Tungsten. Other materials are available on request.
Applications of
Macor Machinable Glass Ceramics
Ultra-High Vacuum
Environments
Macor is used as an insulator or coil support and for vacuum
feed-troughs. In these applications the conductive materials are supported by
the Macor
part and a compatible sealing glass is used to produce a vacuum-tight, hermetic
seal.
Constant Vacuum Applications
Macor parts are found in spacers, headers and windows for
microwave tube devices and as sample holders in field ion microscopes.
Aerospace Industry
Over 200 distinctly shaped Macor parts
can be found on America’s reusable Spacer Shuttle Orbiter. Retaining rings of Macor are used
at all hinge points, windows and doors.
Also, large pieces of Macor glass
ceramic are used in a NASA spaceborne gamma radiation detector. For this
application frame corners are joined by a combination of machined (butt-lap)
mechanical joints and a sealing glass.
Nuclear-Related Experiments
Since Macor is not dimensionally affected by irradiation, small
cubes of the material are machined to a tolerance of one micron and are used as
a reference piece to measure dimensional change in other materials.
Welding Nozzles
Welding equipment manufacturers are using Macor as a
nozzle on the tips of oxyacetylene torches. The material’s non-wetting
characteristic means molten particles won’t adhere to and decrease the
effectiveness of the nozzle.
Fixtures
Macor is used as an electrode support and burner block in
several industrial high heat, electrical cutting operations due to its low
thermal conductivity and excellent electrical properties.
Medical Equipment
Producers of medical components are intrigued by Macor machinable
glass ceramic’s inertness, precise machinability and dimensional stability.
Conclusion
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 look at Macor. It will
lower costs and substantially reduce the time between design and actual use.
Source: Ceramic Substrates and Components
For more information on this source please visit Ceramic Substrates and
Components.