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
Thermal conductivity
at 20°C
DIN EN 821-2 λ [W/mK] 125 90 110
Thermal stress
parameters
calculated        
R1 = σB·(1-ν) / (α·E)   R1 [K] 198 157 124
R2 = R1·λ   R2 [W/mm] 25 14 14
Specific electrical
resistance at 20°C
DIN EN 50359 ρ [Ω cm] 103-104 106-108 103-104