Machineable Glass Ceramic - SiO2 46 / Al2O3 16 / MgO 17 / K2O 10 / B2O3 7

This Machineable Ceramic is a white ceramic which can be machined with ordinary steel or carbide tools. It has been used extensively in the Space Shuttle Orbiter.

It can be used continuously up to 800 °C and is a good electrical and thermal insulator. Outgassing in ultra-high vacuum environments can be eliminated, if degassed before use.

MACOR® is non-wetting and can be bonded to itself as well as to various metals, if the MACOR® surfaces are first metallised.

Key Properties

The key properties of MACOR® are tabulated below.

Table 1. Key properties

Chemical Resistance
Acids - concentrated Poor
Acids - dilute Fair
Alkalis Fair
Electrical Properties
Dielectric constant 5.9
Dielectric strength ( kV.mm-1 ) 40
Volume resistivity ( Ohm.cm ) >1014 @ 25 °C
Mechanical Properties
Compressive strength ( MPa ) 345
Hardness - Vickers ( kgf.mm-2 ) 400
Tensile modulus ( GPa ) 67
Physical Properties
Apparent porosity ( % ) 0
Density ( g.cm-3 ) 2.52
Thermal Properties
Coefficient of thermal expansion ( x10-6 K-1 ) 13 @ 20-1000 °C
Specific heat ( J.K-1.kg-1 ) 790 @ 25 °C
Thermal conductivity ( W.m-1.K-1 ) 1.5 @ 20 °C
Upper continuous use temperature ( °C )

800-1000

Source: Goodfellow

For more information on this source please visit Goodfellow.

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