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公开(公告)号：EP0886624A1
公开(公告)日：1998-12-30
申请号：EP97915063
申请日：1997-03-13
申请人： NASA
摘要： A carbon fiber reinforced carbon composite valve for internal combustion engines and the like formed of continuous carbon fibers (15) throughout the valve's stem (11) and head (13) is disclosed. The valve includes braided carbon fiber material (16) over axially aligned unidirectional carbon fibers (15) forming a valve stem (11); the braided (16) and unidirectional carbon fibers (15) being broomed out (18) at one end of the valve stem forming the shape of the valve head (13); the valve-shaped structure being densified and rigidized with a matrix of carbon (21) containing discontinuous carbon fibers (22); and the finished valve being treated to resist oxidation. Also disclosed is a carbon matrix plug containing continuous and discontinuous carbon fibers and forming a net-shape valve head (13) acting as a mandrel over which the unidirectional and braided carbon fibers are formed according to textile processes. Also disclosed are various preform valves and processes for making finished and preform carbon fiber reinforced carbon composite valves.
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公开(公告)号：EP0886624A4
公开(公告)日：2001-01-17
申请号：EP97915063
申请日：1997-03-13
申请人： NASA
摘要： A carbon fiber reinforced carbon composite valve for internal combustion engines and the like formed of continuous carbon fibers (15) throughout the valve's stem (11) and head (13) is disclosed. The valve includes braided carbon fiber material (16) over axially aligned unidirectional carbon fibers (15) forming a valve stem (11); the braided (16) and unidirectional carbon fibers (15) being broomed out (18) at one end of the valve stem forming the shape of the valve head (13); the valve-shaped structure being densified and rigidized with a matrix of carbon (21) containing discontinuous carbon fibers (22); and the finished valve being treated to resist oxidation. Also disclosed is a carbon matrix plug containing continuous and discontinuous carbon fibers and forming a net-shape valve head (13) acting as a mandrel over which the unidirectional and braided carbon fibers are formed according to textile processes. Also disclosed are various preform valves and processes for making finished and preform carbon fiber reinforced carbon composite valves.
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公开(公告)号：EP0912220A4
公开(公告)日：2001-01-17
申请号：EP97916774
申请日：1997-03-06
申请人： NASA
CPC分类号： C04B35/83 , F02F7/0085 , F05C2201/021 , F05C2201/0433 , F05C2201/0448 , F05C2203/0882 , F05C2251/042 , F05C2253/16
摘要： A three-dimensional piston molding is fabricated from a mixture of chopped, carbon tow filaments of variable length, which are prepregged with carbonaceous organic resins and/or pitches and molded by conventional molding processes into near net shape, to form a carbon-fiber reinforced organic-matrix composite part. Continuous reinforcement in the form of carbon-carbon composite tapes or pieces of fabric can be also laid in the mold before or during the charging of the mold with the chopped-fiber mixture, to enhance the strength in the crown (21) and wrist-pin areas (23). The modled chopped-fiber reinforced organic-matrix composite parts are then pyrolyzed in an inert atmosphere, to convert the organic matrix materials to carbon. These pyrolyzed parts are then densified by reimpregnation with resins or pitches, which are subsequently carbonized. Densification is also accomplished by direct infiltration with carbon by vapor deposition processes. Once the desired density has been achieved, the piston molds are machined to final piston dimensions, and piston ring grooves are added. To prevent oxidation and/or to seal the piston surface or near surface, the chopped-fiber piston (20) is coated with ceramic and/or metallic sealants; and/or coated with a catalyst.
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公开(公告)号：EP0888245A4
公开(公告)日：2001-01-17
申请号：EP97916893
申请日：1997-03-06
申请人： NASA
CPC分类号： F02F3/00 , C04B35/83 , F02F7/0085 , F05C2201/021 , F05C2201/0433 , F05C2201/0448 , F05C2203/0808 , F05C2203/0882 , F05C2251/042 , F05C2253/16
摘要： An improved structure for carbon-carbon composite piston architectures is disclosed. Initially, the carbon fabric or tape layers are prepregged with carbonaceous organic resins and/or pitches and these plies (21) laid up or molded about a mandrel, to form a carbon-fiber reinforced organic-matrix composite billets (20) shaped like a 'U' channel having legs (26, 27), a 'T'-bar, or a combination of the two. The molded carbon-fiber reinforced organic-matrix composite part is then pyrolized in an inert atmosphere, to convert the organic matrix materials to carbon. At this point, cylindrical piston blanks (22) are cored from the 'U'-channel, 'T'-bar, or combination part. These blanks are then densified by reimpregnation with resins or pitches which are subsequently carbonized. Densification is also accomplished by direct infiltration with carbon by vapor deposition processes. Once the desired density has been achieved, the piston billets are machined to final piston dimensions; coated with oxidation sealants; and/or coated with a catalyst.
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