Silicon Carbide - Reaction Bonded

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For over 60 years we have been a precision machining and polishing fabricator of parts from all technical ceramics, sapphire, glass and quartz. We machine these materials to very precise tolerances (many times measured in millionths of an inch) for dimension, flatness, wedge and roundness or cylindricity. Our customers typically have a critical application that requires extremely tight tolerances in ultra-hard materials. We also have the capability to grind and polish spherical radius parts in a variety of hard materials, both inside and outside diameters, to optical requirements.

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Silicon Carbide is among the hardest of ceramics, and retains hardness and strength at elevated temperatures, which translates into among the best wear resistance also.  Additionally, SiC has a high thermal conductivity, especially in the CVD (chemical vapor deposition) grade, which aids in thermal shock resistance.  It is also half the weight of steel.

Based on this combination of hardness, resistance to wear, heat and corrosion, SiC is often specified for seal faces and high performance pump parts.

Reaction Bonded SiC has the lowest cost production technique with a course grain. It provides somewhat lower hardness and use temperature, but higher thermal conductivity.

Direct Sintered SiC is better grade than Reaction Bonded and is commonly specified for high temperature work.

CVD SiC® is a face centered cubic, polycrystalline form produced by chemical vapor deposition. This material is extremely pure, and is specified for it's excellent thermal conductivity approaching 300 W/mK. It is considerably more expensive to produce than the sintered or reaction bonded grades. ® Rohm & Haas.

Chemical Formula


3.1 - 3.2 gm/cc

2500-2550 Knoop

Tensile Strength
44.5 kpsi
Modulus of Elasticity

57 - 65 x 106 psi

Flexural Strength
67 - 95 kpsi
Compressive Strength
360 - 362 kpsi
Poisson's Ratio
0.14 - 0.19
Fracture Toughness
4 - 5 MPa m<sup>½</sup>
Volume Resistivity

1 x 104 ohm-cm

Coefficient of Thermal Expansion

4.3 - 4.5 x 10-6/°C

Thermal Conductivity
110 - 155 W/mK
Specific Heat
0.67 cal/g °C
Shock Resistance
400 °C Diff.
Maximum Working Temperature
1650 °C

All properties are at room temperature unless otherwise noted.

Engineering data are representative, and are not intended as absolute nor warrantable. Manufacturer’s Data shown is blended from multiple sources and therefore illustrates the marketplace.

*Click on a Property to see a comparison of up to 10 materials