Macor ^® MGC (Machinable Glass Ceramic) Specifications

TECHNICAL DESCRIPTION

Macor ^® is a white, odorless, porcelain-like (in appearance) material composed of approximately 55% fluorophlogopite mica and 45% borosilicate glass. It contains the following compounds (in weight percent):

• Silicon ( Si O ₂ ) 46%   • Magnesium ( Mg O ) 17%   • Aluminum ( Al ₂ O ₃ ) 16%   • Potassium ( K ₂ O ) 10%   • Boron ( B ₂ O ₃ ) 7%   • Fluorine ( F ) 4%

GENERAL PROPERTIES

Macor ^® Machinable Glass Ceramic is 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. And when properly baked out, it won't outgas in vacuum environments. Macor ^® is WHITE in color.

MACHINING RECOMMENDATIONS

Macor ^® may be machined using standard metal working tools and operations, including lathes, drills, mills, and machining centers. Macor ^® machining tolerances are surprisingly tight, up to .0005". It can be machined to a surface finish of less than 20 µin. and polished to a smoothness of 0.5 µin.-AA finish.

High speed steel tools may be used, but carbide tools are recommended for longer wear. Water-soluble coolants which are recommended for glass or ceramics should be used, such as Cimstar-40 Pink. No post firing is required after machining. Recommended equipment, feeds and speeds include:
    • Grinding --- diamond, silicon-carbide or aluminum-oxide grinding wheel
    • Sawing --- 100 fpm band speed carbide grit, silicon-carbide or diamond wheel
    • Turning --- 30-50 sfm, .002-.005 ipr, .150” cut depth
    • Milling --- 20-35 sfm, .002 ipt, .150”-.200” cut depth
    • Drilling --- ¼” dia - 300 rpm, .005 ipr   /   ½” dia - 250 rpm, .007 ipr   /   1” dia - 100 rpm, .010 ipr

SEALING, JOINING AND METALIZING
Macor ^® MGC can also be joined or sealed - both to itself and to other materials - in a number of ways: metalized 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 metalized using metal inks, or thin film metalized by sputtering.

TYPICAL APPLICATIONS
• Ultra High Vacuum Environments • Constant Vacuum Applications - microwave spacers, headers, windows • Aerospace Industry - retaining rings, radiation detectors • Nuclear-Related Experiments - reference cubes • Welding Nozzles • Fixtures, Electrodes, Burner Blocks • Medical Equipment

TYPICAL PROPERTIES of MACOR ® MGC
ASTM or UL test	Property	Macor ® MGC
PHYSICAL
D792	Density (lb/in³) (g/cm³)	0.091 2.52
D570	Water Absorption, 24 hrs (%)	0.01
MECHANICAL
D695	Compressive Strength (psi)	50,000
D790	Flexural Strength (psi)	13,600
-	Modulus of Elasticity (psi)	9,700,000
-	Shear Modulus (psi)	3,700,000
-	Poisson's Ratio	0.29
D785	Hardness, Rockwell	A48
THERMAL
D696	Coefficient of Linear Thermal Expansion (x 10 -6 in./in./°F)	5.20
D648	Heat Deflection Temp (°F / °C) at 264 psi	240 / 116
D3418	Melting Temperature (°F / °C)	none
-	Max Operating Temp (°F / °C)	1832 / 1000
C177	Thermal Conductivity (BTU-in/ft²-hr-°F) (x 10 -4 cal/cm-sec-°C)	10.16 34.9
UL94	Flammability Rating	none
ELECTRICAL
D149	Dielectric Strength (V/mil) short time, 1/8" thick	1000
D150	Dielectric Constant at 1 KHz	6.03
D150	Dissipation Factor at 60 Hz	-
D257	Volume Resistivity (ohm-cm)at 50% RH	> 10 16

NOTE: The information contained herein are typical values intended for reference and comparison purposes only. They should NOT be used as a basis for design specifications or quality control. Contact us for manufacturers' complete material property datasheets.
All values at 73°F (23°C) unless otherwise noted.

MACOR is a registered trademark of Corning Incorporated