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Polishing of Silicon Carbide - SiC
The surface finish which is ultimately obtainable by polishing depends on the manufacturing process of the silicon carbide. The type of manufacturing process determines its density, grain size and hardness. Silicon carbide is available as solid CVD (Chemical Vapor Deposition), pressed, and single crystal.
Attainable tolerances on polished silicon carbide parts:
- Flatness to a fraction of a wave
- Thickness to millionths of an inch
- Parallelism to millionths of an inch
Note: For best pricing, choose loosest acceptable tolerances.
Silicon carbide surface finishes attainable by polishing:
-
- Silicon carbide manufactured by CVD process can be polished to a finish of a few Angstroms.
- Reaction bonded silicon carbide can be polished to 20 – 50 Angstrom finish only.
- Hot pressed silicon carbide is polishable to 50 – 100 Angstrom level.
- Sintered silicon carbide polishes to 100 Angstroms and often much higher, depending on material quality.
Properties of different types of silicon carbide
| SiC Type |
Density |
Therm. Cond.
W/mK |
CTE x 10-6 |
|
20°C |
1000°C |
| CVD |
3.21 |
300 |
2.2 |
4.0 |
| Reaction bonded |
2.4 – 3.7 |
50 – 170 |
2.2 – 2.5 |
4.0 – 6.8 |
| Hot pressed |
3.1 – 3.3 |
50 – 160 |
2.3 – 2.5 |
4.3 – 4.5 |
| Sintered |
3.0 – 3.2 |
40 – 150 |
1.0 – 1.5 |
4.5 – 5.2 |
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