Single-cycle rapid densification of carbon/carbon components for air and space applications
A method of producing a densified carbon fiber reinforced carbon (carbon/carbon) component includes placing a carbon/carbon preform and preform heater(s) into a reactor vessel with an immersing quantity of a precursor liquid (e.g., hydrocarbon). The reactor vessel includes a condenser for condensing precursor gases (e.g., carbonaceous gases) produced during densification and thereby maintain a thermodynamic equilibrium. Electrical current is supplied to the preform heater over a multi-hour period of densification in which the precursor liquid is continually boiled and the precursor gases continually produced. The current is sufficient to maintain the preform at a densification temperature above a precursor cracking temperature, thereby causing the precursor gases to be diffused into the preform and dissociated gas species to be deposited. Densification begins within the preform and advances outwardly along a densification front until completion.
1 . A method of producing a densified carbon fiber reinforced carbon (carbon/carbon) component, comprising:
placing a carbon/carbon preform and one or more preform heaters into a reactor vessel along with an immersing quantity of precursor liquid, the reactor vessel including a condenser for condensing gases of the precursor produced during densification of the preform and thereby maintaining a thermodynamic equilibrium in the reactor vessel; and
supplying electrical current to the one or more preform heaters over a multi-hour period of the densification in which the precursor liquid is continually boiled and the precursor gases continually produced, the electrical current being sufficient to maintain the preform at a densification temperature above a cracking temperature of the precursor, thereby causing the precursor gases to be diffused into the preform and dissociated species of the gases to be deposited on the preform, with densification beginning within the preform and advancing outwardly along a densification front until completion,
wherein the one or more preform heaters includes one or more inductive heating coils disposed in a susceptor, the susceptor being in contact with the surface of the preform, with a temperature gradient generated between the susceptor and the precursor liquid across the preform.
2 . The method of claim 1 , wherein the preform has a shape forming a hollow, and the one or more preform heaters is shaped and sized to fit within the hollow and is placed in the hollow.
3 . The method of claim 2 , wherein the preform shape is conical, and the densified carbon/carbon component is a shield for an air vehicle nosecone.
4 . The method of claim 1 , wherein the susceptor is operative to convert magnetic energy from the one or more heating coils to thermal energy conducted to the preform.
5 . The method of claim 1 , wherein the preform has a shape forming a hollow, and the one or more heating coils and susceptor are shaped and sized to fit within the hollow with the susceptor in contact with the surface of the preform for conductive heat transfer.
6 . The method of claim 1 , wherein the densification front is formed and advanced based on a thermal gradient between the surface of the preform in contact with the susceptor and a second surface of the preform in contact with, and cooled by, the precursor liquid.
7 . The method of claim 1 , wherein the preform is of a phenolic prepreg material and is carbonized and graphitized by the densification.
8 . The method of claim 1 , wherein the electrical current is supplied at an operating voltage in a range from 5 to 750 volts and an operating frequency in a range of 0.1 kHz to 300 MHz.
9 . The method of claim 1 , wherein the reactor vessel includes a preform support on which the preform is placed and which holds the preform in constant position relative to the one or more preform heaters.
10 . The method of claim 1 , wherein the precursor liquid is a liquid hydrocarbon and the precursor gases are carbonaceous gases.
11 . The method of claim 10 , wherein the liquid hydrocarbon is one of cyclopentane, cyclohexene, hexene-1, gasoline, toluene, methylcyclohexane, cyclohexane, n-hexane, benzene, or a combination thereof.
12 . A method of producing a densified carbon fiber reinforced carbon (carbon/carbon) component, comprising:
placing a carbon/carbon preform and one or more preform heaters into a reactor vessel along with an immersing quantity of preceramic precursor liquid, the reactor vessel including a condenser for condensing organosilane gases produced during densification of the preform and thereby maintaining a thermodynamic equilibrium in the reactor vessel; and
supplying electrical current to the one or more preform heaters over a multi-hour period of the densification in which the preceramic precursor liquid is continually boiled and the organosilane gases continually produced, the electrical current being sufficient to maintain the preform at a densification temperature above a cracking temperature of the precursor, thereby causing the organosilane gases to be diffused into the preform and dissociated species of the gases to be deposited on the preform, with densification beginning within the preform and advancing outwardly along a densification front until completion,
wherein the one or more preform heaters includes one or more inductive heating coils disposed in a susceptor, the susceptor being in contact with the surface of the preform, with a temperature gradient generated between the susceptor and the precursor liquid across the preform.