ruCeramic Matrix Composites (CMC)
Description
Ultrahard structural ceramics are successfully used in tribological applications, including wear-resistant friction pairs of slide bearing operating in severe conditions that involve aggressive media, presence of abrasive inclusions, and high temperatures. Nonetheless, this class of materials has a number of limitations, including:
- low impact resistance
- brittle fracture
- part size and shape limitations
- defect size effect
- limited load level during sliding.
One of the major possible approaches to improve the above limitations is the development of ceramic matrix composite (CMC) materials. CMC is a new class of ceramic-based materials that contain ceramic matrix reinforced by carbon or ceramic fiber.
CMC materials combine the best advantages of the engineering ceramics and fibre-reinforced composites: high hardness and strength, excellent wear and corrosion resistance, moreover, they feature significantly improved fracture toughness and graceful fracture behavior. This combination of properties makes CMC a material of choice for processing of large-sized parts with greater reliability than is ever possible with conventional structural ceramics.
Applications
- Large and thin-walled inserts for tribological assemblies (slide bearings for centrifugal ESP and rotary-vortex pumps) working in sever conditions involving aggressive and abrasive media, elevated temperatures and mechanical loading;
- Face seals, valving parts, actuators for producing and processing machinery for mining, petrochemical and gas sectors
CMC are the enabling materials for the designers of large and high-capacity pumping equipment; offering unique capabilities for controlling slide bearing performance. By tailoring such parameters as reinforcement architecture, matrix/reinforcement ratio, and interfaces one could design tribotechnical assemblies that make effective use of counterbodies based on ultrahard ceramics, or hardened steels, etc.
Physical and mechanical parameters
| Material | Density, g/cm³ | Porosity, not more than %
| Transverse rupture strength, MPa | Impact toughness, kJ•mˆ(-2) | Young modulus, GPa | Content free of Si, % |
| Type А | 2,0 - 2,5 | 1,0 | 180 - 350 | 7 - 14 | 280 - 350 | 3,0 - 6,0 |
| Type Б | 1,7 - 2,0 | 9,0 | 90 - 350 | 10 - 20 | 250 - 280 | 1,0 - 3,0 |
| Parameter | Material | |
| CMC type А | SiSiC | |
| Density, g/cm³ | 2,00 - 2,50 | 3,05 - 3,11 |
| Transverse rupture strength, MPa | 180 - 350 | 300 - 450 |
| The nature of the destruction |
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| Fracture toughness, MPa m½ | 15,0 - 20,0 | 3,5 - 4,5 |
