Method of making carbon-carbon composite
Methods of making a carbon-carbon composite from thermosetting polymer resin include (a) infusing bis-Schiff base resin into a carbon fiber reinforcement to form an uncured resin embedded composite, (b) positioning the uncured resin embedded composite on a substrate under a vacuum enclosure, (c) curing the bis-Schiff base resin at a first elevated temperature under vacuum to form a polymer matrix composite, (d) heating the polymer matrix composite at a second elevated temperature under inert atmosphere to form a porous carbon-carbon composite, (e) re-infusing bis-Schiff base resin into the porous carbon-carbon composite and curing under vacuum at a third elevated temperature to generate a reinfused porous carbon-carbon composite, and (f) heating the reinfused porous carbon-carbon composite at a fourth elevated temperature under inert gas to form the carbon-carbon composite. Further, the second elevated temperature and/or the fourth elevated temperature is less than 900° C.
1 . A method of making a carbon-carbon composite from thermosetting polymer resin comprising the steps of:
a) infusing bis-Schiff base resin into carbon fiber reinforcement to form an uncured resin embedded composite, the bis-Schiff base resin comprising the structure of Formula (I):
wherein:
R comprises at least one aromatic moiety,
X comprises an aromatic moiety, an aliphatic moiety, or a hydrogen and X′ comprises an aromatic moiety, an aliphatic moiety, or a hydrogen;
b) positioning the resin embedded composite on a substrate under a vacuum enclosure;
c) curing the carbon fiber reinforcement embedded with bis-Schiff base resin at a first elevated temperature under vacuum to form a polymer matrix composite;
d) heating the polymer matrix composite at a second elevated temperature under inert atmosphere to form a porous carbon-carbon composite;
e) re-infusing bis-Schiff base resin into the porous carbon-carbon composite resulting from step (d) and curing the newly infused bis-Schiff base resin at a third elevated temperature to generate a reinfused porous carbon-carbon composite; and
f) heating the reinfused porous composite resulting from step (e) at a fourth elevated temperature under inert gas to densify the resulting reinfused carbon-carbon composite from step (e) and form the carbon-carbon composite;
wherein the second elevated temperature and/or the fourth elevated temperature is less than 900° C.
2 . The method of claim 1 wherein the carbon fiber reinforcement is unidirectional fibers, woven fabric, braided fabric, or 3D fiber preform.
3 . The method of claim 1 wherein the resin embedded composite is a prepreg.
4 . The method of claim 1 wherein the infusion step of step (a) and/or step (e) is conducted with a pressure differential between the composite and a source of the bis-Schiff base resin.
5 . The method of claim 1 wherein the steps (e) and (f) are repeated 4 times or less for a total of 5 or less cycles.
6 . The method of claim 5 wherein the carbon-carbon composite from step (f) is heated to a fifth temperature of 900° C. to 1800° C. on one or more of the cycles.
7 . The method of claim 5 wherein the carbon-carbon composite from step (f) is heated to a fifth temperature of 1100° C. to 1700° C. on one or more of the cycles.
8 . The method of claim 5 wherein the carbon-carbon composite from step (f) is heated to a fifth temperature of 1200° C. to 1600° C. on one or more of the cycles.
9 . The method of claim 1 wherein the steps (e) and (f) are repeated 3 times or less for a total of 4 or less cycles.
10 . The method of claim 1 wherein the steps (e) and (f) are repeated 2 times or less for a total of 3 or less cycles.
11 . The method of claim 1 wherein the carbon-carbon composite from step (f) is heated to a fifth temperature of 900° C. to 1800° C.
12 . The method of claim 1 wherein the carbon-carbon composite from step (f) is heated to a fifth temperature of 1100° C. to 1700° C.
13 . The method of claim 1 wherein the carbon-carbon composite from step (f) is heated to a fifth temperature of 1200° C. to 1600° C.
14 . The method of claim 1 wherein the bulk density of the carbon-carbon composite is greater than 1.6 g/cm3.
15 . The method of claim 1 , wherein the vacuum enclosure comprises a vacuum bag.
16 . The method of claim 1 , wherein the vacuum applied in step (c) is 25 inches of Hg or greater.
17 . The method of claim 1 , wherein the vacuum applied in step (e) is 25 inches of Hg or greater.
18 . The method of claim 1 , wherein the bis-Schiff base resin has a viscosity below 100,000 cP at 170° C.
19 . The method of claim 1 , wherein the char yield of the bis-Schiff resin in the carbon-carbon composite is greater than 50%.
20 . The method of claim 1 , wherein the first elevated temperature and the third elevated temperature are substantially the same.