ruSintered silicon carbide (SSiC) and liquid phase – sintered silicon carbide (LP SiC)
Description
Sintered silicon carbide (SSiC) is processed by pressureless sintering.
SSiC, as compared to SiSiC (silicon-infiltrated silicon carbide ), is a single-phase material, and thus is superior to SiSiC in resistance against aggressive liquids (chemical stability).
VIRIAL SSiC grade is processed according to the draft internal company standard TU 1915-036-23042805-2010.
The major disadvantage of both SSiC and SiSiC is their poor fracture toughness that leads to considerable brittleness of these two materials. Liquid phase – sintered SiC (LP SiC) is an alternative SiC-based material with improved physical and mechanical parameters. The microstructures of LP SiC and SSiC differ in several important aspects: 1) grain morphology (elongated grains in SSiC and equiaxed grains in LP SiC); 2) aspect ratio (LP SiC has grains one order of magnitude smaller than SSiC). On the other hand, LP SiC contains considerable amount of oxide dopants that form liquid phase during sintering, which undermines significantly its resistance to corrosion.
Applications
SSiC parts are recommended for prolonged operation in abrasive media due to their excellent tribological parameters attributable to high hardness, Young modulus and thermal conductivity.
Similar to SiSiC, SSiC parts are used in slide bearings (axial and radial), face seals for different types of oil/gas and chemical pumps, valving, and wear parts of processing equipment (nozzles, dies, etc.).
In contrast to SiSiC, the SSiC parts may be recommended for use in virtually any aggressive media with pH ranging from 0 to 14.
|
Parameter |
Material | |
|
SSiC |
LPSiC | |
|
Density, g/cm³ |
3,12 – 3,17 |
3,21 - 3,25
|
|
Microstructure feature size |
200 μm |
10 μm |
|
Transverse rupture strength, MPa |
350 - 450 |
500 - 550 |
|
Young modulus, GPa |
390 - 420 |
400 - 430 |
|
Vickers’ microhardness, GPa |
23 - 28 |
22 - 25 |
|
Fracture toughness, MPa m½ |
3,0 - 4,0 |
4,0 - 5,0 |
|
Thermal conductivity, W mˆ(-1) x Кˆ(-1) |
90 - 130 |
70 - 90 |
|
Thermal expansion ratio, 10ˆ(-6) x Кˆ(-1) |
4,0 – 4.5 |
5,0 – 5.5 |
