Ceramic Matrix Composites (CMC)
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.
- 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.
|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|
|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|
|Fracture toughness, MPa m½||15,0 - 20,0||3,5 - 4,5|