摘要:
Ceramic composite materials that are reinforced with carbide fibers can exhibit ultra-high temperature resistance. For example, such materials may exhibit very low creep at temperatures of up to 2700°F (1480°C). The present composites are specifically engineered to exhibit matched thermodynamically stable crystalline phases between the materials included within the composite. In other words, the reinforcing fibers, a debonding interface layer disposed over the reinforcing fibers, and the matrix material of the composite may all be of the same crystalline structural phase (all hexagonal), for increased compatibility and improved properties. Such composite materials may be used in numerous applications.
摘要:
A method of forming a ceramic matrix composite structure. The method comprises forming at least one prepregged composite material comprising a ceramic fiber preform and a pre-ceramic matrix slurry. The ceramic fiber preform may comprise a single tow of ceramic fibers, a tape of multiple tows or a woven fabric. The at least one prepregged composite material is placed over at least one surface of a tool using an advanced fiber placement apparatus to form an at least partially uncured composite material structure. The at least partially uncured composite material structure is exposed at least to elevated temperatures to convert the at least partially uncured composite material structure into a ceramic matrix composite structure. A system for forming a ceramic matrix composite structure, an advanced fiber placement apparatus, and a ceramic matrix composite structure are also described. The ceramic matrix can be both an oxide and non-oxide.
摘要:
A composite structure includes a matrix material and a carbon nanotube (CNT)- infused fiber material that includes a plurality of carbon nanotubes (CNTs) infused to a fiber material. The CNT-infused fiber material is disposed throughout a portion of the matrix material. The composite structure is adapted for application of a current through the CNT- infused fiber material to provide heating of the composite structure. A heating element includes a CNT-infused fiber material includes a plurality of CNTs infused to a fiber material. The CNT-infused fiber material is of sufficient proportions to provide heating to a structure in need thereof.
摘要:
Procédé de traitement de fibres céramiques (10) à base de carbure métallique comprenant un premier traitement thermique en voie gazeuse réactive (S1) réalisé avec au moins un premier gaz réactif de type halogène formant, par transformation chimique de la fibre en surface, une couche superficielle (12) constituée majoritairement de carbone et un deuxième traitement thermique en voie gazeuse réactive (S2) réalisé avec au moins un deuxième gaz réactif éliminant la couche superficielle formée en surface lors de la transformation chimique.
摘要:
A fiber reinforced matrix composite mirror (40 ) that eliminates the problem “of print through". A layer (52) of small unbundled fibers (54) in the matrix (44) diffuses and randomize any stresses that are created by the weave pattern (42) of the fiber reinforcement so that the coarse texture is not transferred to the optical quality surface (55) thus eliminating "print through". The layer (52) can be provided in a variety of embodiments using random fibrils, a c ontinuous fiber mat or a weave of single or finely towed continuous fibers. The fiber reinforced mirror is constructed by adding a mixture of matrix pre-cursor and fibers or fibrils to a common graphite fiber reinforced matrix construction.
摘要:
A ceramic composite having a ceramic coating formed from a ceramic forming polymer of adjustable composition. The ceramic forming polymer is capable of producing a weak interface-type fiber coating for the ceramic composite, resists oxidation and is less expensive to apply. The invention also includes methods of using a ceramic forming polymer to provide fiber coatings tailored to the type of matrix, fiber, or other reinforcement used. The material forms micro-porous and nano-porous coatings on the fibers. The porosity in the coatings provides a low strength interface between the fiber and matrix that imparts the toughness needed in the composite. The material can be provided with controlled ratios of carbon, silicon, oxygen and hyrdrogen to optimize bonding to the fibers, bonding of the matrix to the fiber coating, and environmental protection of the fibers.
摘要:
A process for enhancing the expansion of intercalated graphite flake is presented. The process includes annealing the graphite flake at a temperature of at least about 3000°C prior to intercalation and intercalating in the presence of a lubricious additive.
摘要:
Improved composite structure comprises threads (1) distributed within disperse matrix. The structure has increased strength by virtue of distance between the points of support of the thread span, which is deliberately selected to be less than the distance corresponding to the critical lengths corresponding to buckling. The structure is suitable for various articles of manufacture requiring improved strength-to-weight or rigidity-to-weight ratio in various directions.