US-12623406-B2 - Systems and methods for additive manufacturing to produce carbon-carbon parts with improved properties and reduced manufacturing times

US12623406B2US 12623406 B2US12623406 B2US 12623406B2US-12623406-B2

Abstract

Systems for manufacturing a Stage 1 carbon-carbon (CC) part, including a resin infused with at least one of chopped fibers, milled fibers, or a continuous fiber. The resin further may include at least one UV initiator to render the resin UV gellable upon exposure to UV light. An additive manufacturing (AM) system determines and provides tool paths needed to provide an engineered characteristic to the Stage 1 CC part. A print nozzle component of the AM system extrudes the resin in accordance with the tool paths onto a sacrificial support material layer, such that the fiber(s) are deposited in desired orientations, within each layer, in a layer-by-layer printing operation. A UV light illuminates the resin after extrusion to initiate gelation of the resin as the resin is extruded onto the sacrificial material layer, to thus form a precursor part having an imparted or enhanced performance characteristic. A pyrolysis subsystem may be used for pyrolyzing the precursor part to create the Stage 1 CC part.

Inventors

James Lewicki

Assignees

LAWRENCE LIVERMORE NATIONAL SECURITY, LLC

Dates

Publication Date: 20260512
Application Date: 20230217

Claims (16)

1 . A system for manufacturing a Stage 1 carbon-carbon (CC) part, comprising: a thixotropic photogellable additive manufacturing ink comprising: (i) a resin comprising a cyanate ester resin, cyanurate resin, and a bisphenol F epoxy resin, wherein the cyanate ester resin is present at a level of from about 35% to about 45% by weight of the ink; (ii) a UV initiator; (iii) from about 20% to about 60% of carbon fibers selected from the group consisting of chopped fibers, milled fibers, a continuous fiber, and combinations thereof; and (iv) from about 1% to about 25% of a thixotropic agent; (v) wherein the thixotropic photogellable additive manufacturing ink has a gel point operable for interlayer consolidation; an additive manufacturing system comprising: (i) an electronic controller configured to determine and provide tool paths to provide an engineered characteristic to the Stage 1 CC part; (ii) a print nozzle component configured to extrude the thixotropic photogellable additive manufacturing ink in a plurality of deposited layers on a sacrificial support material in accordance with the tool paths, the tool paths being designed to cause the print nozzle component to deposit the thixotropic photogellable additive manufacturing ink in the plurality of deposited layers in a layer-by-layer printing operation, such that the carbon fibers are deposited in desired orientations within each of the deposited layers as the print nozzle component moves along the tool paths; and (iii) a UV light configured to direct UV illumination at the thixotropic photogellable additive manufacturing ink after the extrusion of the thixotropic photogellable additive manufacturing ink by the print nozzle component so as to initiate gelation of the resin upon the extrusion of the thixotropic photogellable additive manufacturing ink, to form a precursor part having an imparted or enhanced performance characteristic; (iv) wherein the system is configured to partially cure the thixotropic photogellable additive manufacturing ink during the deposit of the thixotropic photogellable additive manufacturing ink while allowing molecular diffusion across the layers of the deposited thixotropic photogellable additive manufacturing ink; and a pyrolysis subsystem configured to pyrolyze the precursor part printed using the AM system to create the Stage 1 CC part.
2 . The system of claim 1 , wherein the additive manufacturing ink comprises the continuous fiber and at least one of chopped fibers or milled fibers.
3 . The system of claim 1 , wherein the the cyanate ester and the cyanurate resin are present in the composition at a ratio of from about 80:20 to about 50:50.
4 . The system of claim 1 , wherein the thixotropic agent comprises high surface area fumed silica.
5 . The system of claim 1 , wherein the additive manufacturing ink further comprises from about 2% to about 10% of an additive selected from the group consisting of nano-platelets and nanofibers.
6 . The system of claim 5 , wherein the additive manufacturing ink further comprises ceramic nano fibers.
7 . The system of claim 6 , wherein the ceramic nano fibers are selected from the group consisting of silicon carbide (SiC) fibers, boron nitride (BN) fibers, or mixtures thereof.
8 . The system of claim 1 , wherein the carbon fibers have a length of between 0.5 μm to 2000 μm.
9 . The system of claim 8 , wherein the resin has a loading of the carbon fibers of from about 20 to about 60% by volume.
10 . The system of claim 8 , wherein the additive manufacturing ink further comprises an epoxy functional colloidal silica nanoparticle dispersion.
11 . The system of claim 1 , wherein the UV initiator is selected from the group consisting of a type 1 UV initiator, a type 2 UV initiator, cationic ring-opening UV initiator, and mixtures thereof.
12 . The system of claim 1 , wherein the additive manufacturing ink further comprises rare earth organometallic epoxy curatives, a transition metal organic coordination complex, or a mixture thereof.
13 . The system of claim 1 , wherein the additive manufacturing ink is doped with a transition metal salt.
14 . The system of claim 1 , further comprising a densification subsystem including at least one resin bath and a pyrolysis subsystem, for further densifying the Stage 1 CC part.
15 . A method for producing a Stage 1 carbon-carbon (CC) part, comprising using the system of claim 1 , the method comprising: creating the tool path needed to provide, the engineered characteristic to the Stage 1 CC part; extruding the thixotropic photogellable additive manufacturing ink through the print nozzle component in accordance with the tool path onto a the sacrificial support material layer, the tool path being designed to cause the print nozzle component to deposit the thixotropic photogellable additive manufacturing ink in the layer-by-layer printing operation, such that the carbon fibers are deposited in the desired orientations within each of the deposited layers; and exposing the additive manufacturing ink to UV illumination using the UV light after the resin in extruded from the print nozzle component so as to initiate gelation of the resin upon the extrusion of the thixotropic photogellable additive manufacturing ink, to form a precursor part having an imparted or enhanced performance characteristic; and pyrolyzing the precursor part to create the Stage 1 CC part using the pyrolysis subsystem.
16 . The method of claim 15 , further comprising densifying the Stage 1 CC part.

Description

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with Government support under Contract No. DE-AC52-07NA27344 awarded by the United States Department of Energy. The Government has certain rights in the invention. FIELD The present disclosure relates to additive manufacturing systems and methods, and more particularly to new methods for producing carbon-carbon parts with engineered properties. BACKGROUND The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. Carbon-carbon components are a form of thermally resistant, inorganic, semi-ceramic composite containing a structurally reinforcing carbon fiber filamentary fraction within a continuous phase of sp2 hybridized crystalline and amorphous, graphitic carbon. Carbon-carbon components (“CC”) almost always are formed from thermal processing of a carbon fiber/organic resin precursor system. CC components find wide use in the Aerospace and Defense industries as lightweight, thermally resistant materials for use as heatshields, rocket skirts, aerodynamic leading edges, encased thermal protection systems, as well as in other components and areas. There are two main commercial routes to obtain CC components: pyrolysis and chemical vapor deposition (CVD). Pyrolysis has the advantage of scalability and the disadvantage of loss of volume, formation of voids, cracking/stress, and the need to somehow fill those voids in again with more carbon precursor, and to then pyrolyze again for many cycles. Accordingly, pyrolysis is therefore both time and energy intensive. Furthermore, the non-idealities of the starting materials' structure and the uncertainties of the void formation process can lead to stress concentrations, defects, distortion, cracking, and failure of parts. The yield from a traditional multistage pyrolytic CC process for large complex parts is therefore typically low. CVD has the advantage that it does not require multiple pyrolysis and backfill operations, but it has the disadvantage of the time expense of building up a large structure, single molecular layers at a time. Possibly, the “best” CVD process is one that NASA has used for manufacturing the heat resistant tiles used on the space shuttle, which is a hybrid between pyrolysis and CVD. With this process a single pyrolysis cycle is conducted on a wet wound or prepreg carbon fiber organic layup. Then high temperature ethylene CVD is conducted over an extended timescale to grow carbon within the voids (i.e., typically over weeks at 3000° F.). The final part quality is high, but the cost of carrying out this manufacturing process is extremely high. A second major disadvantage of the CVD based processes is this possibility of diffusion of the gaseous precursor. This is because the surface-to-volume ratio of the parts decreases as one starts to approach full density. Accordingly, there exists a strong need in the industry for an improved carbon-carbon manufacturing process which requires fewer thermal and resin infiltration operations, and which can therefore be carried out in a much more cost effective, and shorter time frame, manufacturing process. There is a further need for a carbon-carbon manufacturing process in which a resin used by the system can be tailored to impart specific, engineered features to the finished carbon-carbon part, when used in a printing operation carried out using an additive manufacturing system. SUMMARY In various aspects the present technology provides additive manufacturing systems, processes and compositions. For example, the present technology provides systems for manufacturing a Stage 1 carbon-carbon (CC) part, comprising: a photogellable additive manufacturing ink comprising a resin, a UV initiator, and at least one of chopped fibers, milled fibers or a continuous fiber;an additive manufacturing system:an electronic controller for determining and providing tool paths to provide an engineered characteristic to the Stage 1 CC part;a print nozzle for extruding the additive manufacturing ink in accordance with the tool paths onto a sacrificial support material layer, the toolpaths being designed to cause the nozzle to deposit the additive manufacturing ink and the at least one of the continuous fiber, the chopped fibers or the milled fibers in desired orientations as the print nozzle moves along the tool paths, within each layer, in a layer-by-layer printing operation; anda UV light for directing UV illumination at the additive manufacturing ink after the additive manufacturing ink in extruded from the print nozzle to initiate gelation of the resin upon extrusion of the additive manufacturing ink by the nozzle onto the sacrificial material layer, to form a precursor part having an imparted or enhanced performance characteristic; anda pyrolysis subsystem for pyrolyzing the precursor part printed using the AM system to create the Stage 1 CC part. In various embodiments, the additi