Specifications of Silicon Carbide Seals

Silicon Carbide

Material properties

Norm

Symbol/Unit

F

F plus

T

Density

DIN EN 623-2

ρ [g/cm3]

>3.10

>3.16

>3.21

Porosity

DIN EN 623-2

P [%]

<3.0

<1.0

<1.0

Mean grain size

[μm]

<5

<5

<2

Grain size distribution

[μm]

Phase composition

α-SiC

α-SiC

α-SiC,
YAG

Vickers hardness

DIN EN 843-4

HV 1 [GPa]

25.5

25.5

22.5

Knoop hardness

DIN EN 843-4

HK 0.1 [GPa]

24.5

24.5

21.0

Young's modulus

DIN EN 843-2

E [GPa]

410

420

420

Weibull modulus

DIN EN 843-5

m

10

15

15

Flexural strength,
4-pt bending

DIN EN 843-1

σB [MPa]

400

510

550

Compressive strength

σD [MPa]

2200

2200

2500

Poisson ratio

ν

0.17

0.17

0.16

Fracture toughness
(SENB)

Klc [MPa·m0,5]

4

4

6

Coefficient of
thermal expansion

DIN EN 821-1

20°C - 500°C

α [10-6/K]

4.1

4.1

3.5

500°C - 1000°C

α [10-6/K]

5.2

5.2

5.2

Specific heat at 20°C

DIN EN 821-3

cp [J/g K]

0.6

0.6

0.6

Thermal conductivity
at 20°C

DIN EN 821-2

λ [W/mK]

125

125

75

Thermal stress
parameters

calculated

R1 = σB·(1-ν) / (α·E)

R1 [K]

198

246

314

R2 = R1·λ

R2 [W/mm]

25

31

24

Specific electrical
resistance at 20°C

DIN EN 50359

ρ [Ω cm]

106-108

106-108

102-103

Silicon Carbide

Material properties

Norm

Symbol/Unit

C

P

G

Density

DIN EN 623-2

ρ [g/cm3]

>3.10

>2.76-
2.89

>3.02

Porosity

DIN EN 623-2

P [%]

<3.0

10-14

<3.0

Mean grain size

[μm]

bimodal

<5

bimodal

Grain size distribution

[μm]

10-1500

10-1000

Phase composition

α-SiC

α-SiC

α-SiC,
graphite

Vickers hardness

DIN EN 843-4

HV 1 [GPa]

25.5

23.5

24.5

Knoop hardness

DIN EN 843-4

HK 0.1 [GPa]

24.5

21.6

23.0

Young's modulus

DIN EN 843-2

E [GPa]

410

340

390

Weibull modulus

DIN EN 843-5

m

10

15

14

Flexural strength,
4-pt bending

DIN EN 843-1

σB [MPa]

400

225

230

Compressive strength

σD [MPa]

2500

2000

2500

Poisson ratio

ν

0.17

0.17

0.16

Fracture toughness
(SENB)

Klc [MPa·m0,5]

3.5

3

3

Coefficient of
thermal expansion

DIN EN 821-1

20°C - 500°C

α [10-6/K]

4.1

3.5

4.0

500°C - 1000°C

α [10-6/K]

5.2

5.6

5.0

Specific heat at 20°C

DIN EN 821-3

cp [J/g K]

0.6

0.6

0.6