1 CARBONCARBON COMPOSITES 2 CC composites are a
1 CARBON-CARBON COMPOSITES
2 CC composites are a new class of engineering materials that are ceramic in nature but exhibit brittle to pseudo-plastic behavior. Carbon fiber reinforcements when embedded in carbonaceous matrix material results in CC composites. As in all composites, the aim is to combine the advantage of high specific strength and stiffness of carbon fibers with the refractory properties of carbon matrix.
APPLICATIONS OF CARBON-CARBON COMPOSITES • High performance braking systems • Refractory material • Heating elements 3 • Turbojet engine components
4 Tomcat-one of the first aircraft to use carbon composites
5 Formula 1 brake disk made of carbon -carbon composites
6 Airplane brake disk
FABRICATION PROCESS 7 • There are two distinct techniques used to fill the interstices between the carbon fibers. These are (i) gas phase using a chemical vapor deposition process, and (ii) the liquid phase route using thermosetting resins or pitch (PIC).
FABRICATION OF CARBON-CARBON COMPOSITES BY CHEMICAL VAPOR DEPOSITION PROCESS • Preparation of carbon/Graphite fiber preform of the desired structure and shape • Densification of the composite by Chemical Vapor Deposition (CVD) technique 8 • Graphitization heat treatment
9 CVD
FABRICATION OF CARBON-CARBON COMPOSITES BY LIQUID PHASE INFILTRATION PROCESS • Preparation of carbon/Graphite fiber preform of the desired structure and shape • Infiltration of the preform with a liquid precursor • Pyrolysis/carbonization • Infiltration – pyrolysis cycle is repeated several (3 -10) times until the desired density is achieved 10 • Graphitization heat treatment
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PROPERTIES OF CARBON-CARBON COMPOSITES • Excellent thermal shock resistance • Low Coefficient of Thermal Expansion • High Thermal Conductivity • High Modulus of Elasticity • Low density • High strength • Low coefficient of friction • Excellent heat resistance in non-oxidizing atmosphere • High abrasion resistance 12 • High electrical conductivity
STRUCTURE OF CARBON-CARBON COMPOSITES • unidirectional structure • bi-directional structure (cloth made of multiple carbon fiber yarns) • multi-directional structure (3 D, 4 D, 5 D, etc. ) 4 D 4 D 5 D 13 3 D
14 • The multidirectional preform technology, also known as the fiber architecture, employs multidisciplinary approaches of structural engineering, mechanical engineering and textile technology to develop preforms in simple blocks, cylinders, cones, contours, surfaces of revolution and complex geometries and shapes.
15 Carbon fiber cloth
16 Carbon fiber cloth
17 Carbon fiber tubes
OXIDATION PROTECTION MECHANISMS a) Surface coatings 18 b) In depth protection
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21 Fibers before and after oxidization
22 Fibers before and after oxidization
23 THANKS FOR YOUR ATTENTION
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