55% fluorophlogopite mica, 45% borosilicate glass

Macor® is a white machinable glass ceramic, manufactured by Corning Inc. that can be machined with ordinary metalworking tools. With the additional use of diamond grinding and polishing methods, such as ours, it can be machined to very precise tolerances and given a highly polished finish. It is often used as a problem solving material due to its special characteristics and the speed with which it can be machined. It is fairly strong and rigid and will not outgas when properly baked out due to its having zero porosity thus making it ideal for ultra-high vacuum applications. However, it is worth bearing in mind that for many designs of large components the finished parts can be considerably more expensive than in Alumina, which is generally a more robust material with better properties than Macor® for most applications.

Main Characteristics

  • Radiation resistant
  • Max working temperature 1000°C (no load)
  • Low thermal conductivity / Good thermal insulation
  • Good electrical insulation
  • Zero porosity
  • No known toxicity

Material Parameters

MACOR® is a white porcelain type material that is non-wetting, odourless and non-outgassing with zero porosity.

It can be machined into bars, tubes, sheets and complex components within the above size limitation.

MACOR® offers tight tolerance capabilities, allowing complicated shape design (optimal performances up to +/- 0.013mm for dimensions, < 0.5µm for finished surfaces and up to 0.013µm for polished surfaces).

MACOR® remains continuously stable at 800°C, with a maximum peak of 1000°C if it is under no load, and unlike ductile materials, does not creep or deform.

There is generally no post firing needed after machining unless it is to be metallised.

MACOR® components are limited in size due to it being manufactured in plates measuring approximately 350 x 330 x 55mm.

MACORS® coefficient of thermal expansion readily matches that of most metals and sealing glasses.

MACOR® is an excellent high voltage insulator at a broad spectrum of frequencies particularly at high temperatures.


Typical Properties of MACOR®

Density g/cm3 2.52
Max working temp (no load) °C 1000
Continuous use °C 800
Coefficient of Thermal Expansion 25°C to 300°C 90×10-7/°C
Knoop Hardness (100g) Kg/mm2 250
Flexural Strength MPa 94
Compressive Strength Mpa 345
Young’s modulus Gpa 66.9
Thermal Conductivity W/m°C 1.46
DC Volume Resistivity ohm.cm 1017
Dielectric Constant 1KHz 6.01
Dielectric Strength (DC) 25°C under 0.03mm thickness kV/mm 129