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Steatite is a low cost material with high electrical resistance at high temperatures, good mechanical strength and a very low dielectric loss factor. Such properties make it ideal for high frequency, low loss, and high voltage insulation. Moreover, steatite is an excellent material for electrical engineering as it can be readily shape sintered into a wide variety of forms such as washers, bushings, resistor forms, spaces and beads. 

Steatite has been used for many years in large-scale industrial systems, household electronic appliances, aerospace and automotive applications, and specialized eletro-technical instruments such as cathode-ray tubes.

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PropertyASTM MethodUnitsL-4L-5
Gas Permeability--n/an/a
DensityC 20-97g/cc2.652.75
Hardness-Mohs Scale77
Water AbsorptionC 20-97%00
Flexural StrengthF417-87psi17,00020,000
Tensile Strength-psi10,00010,000
Compressive Strength-psi80,00085,000
Elastic ModulusC848psi x1061515
Shear ModulusC848psi x10666
Poisson's RatioC848none0.240.24
C.T.E., 25 - 100°CC372-96x10-6/°C7.38.5
C.T.E., 25 - 300°C--7.48.6
C.T.E., 25 - 600°C--7.58.6
Thermal Conductivity, 25°CC408W/m-K33
Max Use Temperature (Non-Loading)-°F23502350
Max Use Temperature (Non-Loading)-°C12901290
Dielectric Strength (.125" Thick)D149-97AV/mil260270
Dielectric Constant @ 1MHzD150-98-5.65.7
Dielectric ConstantD2520-95-5.65.8
Dielectric Loss @ 1MHzD150-98-0.0030.0014
Dielectric LossD2520-95-0.0050.0017
Volume Resistivity, @25°CD257ohms-cm>1E +14>1E +14
Volume Resistivity, @300°C--2E +131E +11
Volume Resistivity, @700°C--2E +092E +10

Note: The information in this data sheet is for design guidance only. STC does not warrant this data as absolute values. Forming methods and specific geometry could affect properties. Slight adjustments can be made to some of the properties to accommodate specific customer requirements. Most of the dense materials in the table are resistant to mechanical erosion and chemical attack. STC has performed ASTM testing qualification for certain compositions, in accordance with ASTM D2442. Please consult our technical staff for appropriate material and specifc test results.

Note: In addition to the above compositions, STC offers a wide range of alternative materials. Please contact one of our applications engineers for material requirements that may not be shown above.

Download the chart as shown above.