Method of making carbon-carbon composite valve for high performance internal combustion engines

Abstract

The present invention provides a carbon-carbon (C/C) composite valve structure useful for high temperature internal combustion engines comprising (a) a carbon-carbon (C/C) composite valve stem having a flared end and a non-flared end opposite the flared end; and (b) a carbon-carbon (C/C) composite valve head applied onto the flared end of the valve stem, wherein at least one of the carbon-carbon (C/C) composite valve stem and head is coated with a high temperature resistant coating. A method is further provided to fabricate the carbon-carbon (C/C) composite valve comprising machining a carbon-carbon (C/C) composite valve stem having a flared end and a non-flared end from a cured and densified carbon-carbon (C/C) plate having a sufficient thickness; applying a plurality of circular fabric plies, made from a balanced carbon-carbon (C/C) prepreg and having a slit in the center of said ply, coaxially onto the non-flared end of said carbon-carbon ((C/C)) valve stem and advancing said plurality of plies to intimately contact the flared end of said carbon-carbon (C/C) valve stem; placing said carbon-carbon (C/C) valve stem contacted with said plurality of circular fabric plies into a die; closing said die and cure pressing said circular fabric plies onto the flared end of said carbon-carbon (C/C) valve stem to form a valve head; carbonizing said press cured carbon-carbon (C/C) composite valve; densifing said carbon-carbon (C/C) composite valve structure; and coating at least one of said carbon-carbon (C/C) composite valve stem and valve head with a high temperature resistant coating comprising an inner layer and an outer layer.