First, the Same Points
- Similar reinforcement: both carbon fiber (or graphite fiber) as the main reinforcement, the material has high strength, high modulus and low density characteristics.
- Excellent high-temperature performance: both can maintain mechanical properties at high temperatures (more than 1000 ℃), suitable for aerospace, brake systems, thermal protection and other fields.
- Low density: density is much lower than metal materials (such as steel or titanium alloy), suitable for lightweight demand scenarios.
- High wear resistance: excellent friction performance, suitable for brake discs, clutches and other high wear scenarios.
Second, the Different Points
Comparison of the two materials
| Carbon-carbon composite (C/C) | Carbon-ceramic composite (C/SiC or C/C-C/SiC) | |
| Matrix material | Carbon matrix (pyrolytic carbon or bituminous carbon) | Ceramic matrix (silicon carbide/SiC based) |
| Oxidation resistance
|
Poor
(coating required above 400°C) Excellent
|
Excellent (SiC matrix oxidation resistance up to 1600°C)
|
| Temperature limit Higher | Higher (up to 2500°C in inert environments) | Slightly lower (long term use approx. 1450°C)
|
| Preparation process
|
Chemical vapor deposition (CVD) + carbonization with multiple dips, long cycle times | Chemical vapor infiltration (CVI) + fusion infiltration, more complex process |
| Hardness and wear resistance | Low
Wear resistance needs to be enhanced by coating |
High hardness (SiC matrix), better wear resistance |
| Coefficient of thermal expansion | Low, significant anisotropy | More homogeneous, better thermal shock resistance |
| Cost
|
High
(long process cycles) |
Higher (complex of raw materials and processes) |
| Application Scenarios | Rocket nozzles, hot press molds, head cones for high-speed aircraft | High-performance brake discs (e.g., for racing cars, airplanes), nuclear reactor components |
Third, Key Differences
-
Substrate and oxidation resistance
The carbon matrix of C/C is easy to oxidize and needs additional coating to protect it; C/SiC can be used for a long time without coating because the SiC matrix has its own antioxidant property.
-
Temperature resistance and thermal stability
C/C has higher temperature resistance in an inert environment, but its performance decreases under high temperature oxidizing environment; C/SiC has better stability in oxidizing environment.
-
Process and Cost
C/C preparation cycle is long, but the process is relatively mature; C/SiC process is complex (need SiC matrix penetration), the cost is higher.
-
Mechanical properties
C/SiC has better hardness, wear resistance and thermal shock resistance than C/C, but C/C has higher strength retention at extreme high temperatures.
Fourth, Typical Applications
C/C composite materials: spacecraft thermal protection system, rocket engine nozzle, monocrystalline silicon growth furnace components, etc.
C/SiC composites: aircraft/high-speed rail brake discs, gas turbine blades, nuclear fusion reactor first wall materials.
The two materials have their own advantages in performance and both represent the research and development direction of cutting-edge composite materials. The specific selection needs to be based on a comprehensive evaluation of actual working conditions, cost, performance and other aspects.