Sacrificial yarn filament for use in ceramic matrix composites, methods of manufacture thereof and articles comprising the same
Disclosed herein is a composite tow comprising a plurality of ceramic filaments; one or more sacrificial yarn filaments; where the sacrificial yarn filaments are operative to undergo decomposition or melting upon being subjected to an elevated temperature; and wherein the sacrificial yarn filaments leave open spaces in the tow upon being subjected to decomposition, dissolution or melting; where the filaments have an average filament diameter of 5 to 15 micrometers.
1 . A composite tow comprising:
a plurality of ceramic filaments; and
one or more sacrificial yarn filaments co-mingled with the plurality of ceramic filaments; where the sacrificial yarn filaments are operative to undergo decomposition, dissolution or melting upon being subjected to an elevated temperature to leave only the plurality of ceramic filaments and open spaces between the plurality of ceramic filaments;
where the ceramic filaments have an average filament diameter of 5 to 15 micrometers;
wherein the sacrificial yarn filament is present in the composite tow in an amount of greater than or equal to 30 volume percent, based on a total volume of the composite tow.
2 . The composite tow of claim 1 , wherein the composite tow has an average diameter of 300 to 1500 micrometers.
3 . The composite tow of claim 1 , wherein the ceramic filaments comprise SiC, Al 2 O 3 , BN, B 4 C, Si 3 N 4 , MoSi 2 , SiO 2 , SiOC, SiNC, and/or SiONC.
4 . The composite tow of claim 1 , wherein the sacrificial yarn filaments comprise metal fibers, ceramic fibers, polymeric fibers or a combination thereof.
5 . The composite tow of claim 4 , wherein the metal fibers and ceramic fibers melt at temperatures of less than 500° C.
6 . The composite tow of claim 4 , wherein the polymeric fibers comprise thermoplastic polymers, blend of thermoplastic polymers, thermosetting polymers, or blends of thermoplastic polymers with thermosetting polymers.
7 . The composite tow of claim 1 , wherein the sacrificial yarn filament comprises a water-soluble polymer, an ethanol soluble polymer, or a combination thereof.
8 . The composite tow of claim 4 , wherein the polymeric fibers comprise a water soluble polymer; and wherein the water-soluble polymer comprises polyvinyl alcohol, polyacrylamide, polyvinyl butyral, or a combination thereof.
9 . The composite tow of claim 1 , wherein the sacrificial yarn filaments are made of one selected from Indium, Cerrobend, Cerrelow 117, Cerrolow 174, Field's alloy, Harper's alloy, Lichtenberg's alloy, Lipowitz's alloy and Newton's alloy.
10 . An article comprising the composite tow of claim 1 .
11 . A method comprising:
co-mingling a plurality of ceramic filaments with one or more sacrificial yarn filaments to form a composite tow; where the ceramic filaments have an average filament diameter of 5 to 15 micrometers; wherein the sacrificial yarn filament is present in the composite tow in an amount of greater than or equal to 30 volume percent, based on a total volume of the composite tow;
decomposing the one or more sacrificial yarn filaments to leave only the plurality of ceramic filaments and open spaces between the plurality of ceramic filaments; and
infiltrating the open spaces with a ceramic precursor to form a tow that includes the ceramic precursor between the plurality of ceramic filaments.
12 . The method of claim 11 , where the composite tow has an average diameter of 300 to 1500 micrometers.
13 . The method of claim 11 , further comprising subjecting the composite tow to an elevated temperature effective to decompose the sacrificial yarn to produce open spaces between the plurality of ceramic filaments.
14 . The method of claim 13 , further comprising reacting the ceramic precursor to form a ceramic matrix.
15 . The method of claim 14 , wherein the ceramic matrix is SiC.
16 . The method of claim 11 , wherein the ceramic filament is SiC.
17 . The method of claim 11 , wherein the sacrificial yarn filament is present in the composite tow in an amount of greater than or equal to 35 volume percent, based on a total volume of the composite tow.