Graphite-based infrastructures for handling molten metals and methods of forming thereof
Described herein are graphite-based infrastructures for high-temperature and/or high-pressure applications and methods of fabricating thereof. Also described are thermal batteries including such infrastructures. An infrastructure may include two graphite structures and a carbide-containing seal positioned between and monolithic with each structure end. The carbide-containing seal may include titanium carbide, zirconium carbide, and/or hafnium carbide. The carbide-containing seal is configured to withstand a temperature of greater than 1500° C. (a) while subjected to an internal pressure of greater than 0.7 MPa (about 100 psi) produced by a molten tin flown through the first structure and the second structure and (b) while remaining monolithic with each of the first-structure sealed end and the second-component sealed end, thereby sealing the two structures. The carbide-containing seal may be formed by graphite fusing, which involves one or more of brazing, reaction bonding, and diffusion bonding.
1 . A method of forming a graphite-based infrastructure for handling a molten metal that can withstand at least one of a high temperature and a high pressure, the method comprising:
positioning a sealing structure between a first graphite component and a second graphite component, wherein:
the first graphite component comprises a first-component initial end directly interfacing the sealing structure,
the second graphite component comprises a second-component initial end directly interfacing the sealing structure,
the sealing structure comprises one or more metals selected from the group consisting of titanium (Ti), zirconium (Zr), hafnium (Hf), silicon (Si), boron (B), and tungsten (W); and
heating the sealing structure, the first-component initial end, and the second-component initial end to at least 600° C., thereby (a) forming a carbide-containing seal by converting the sealing structure, the first-component initial end, and the second-component initial end into the carbide-containing seal and (b) forming a first-component sealed end of the first graphite component and a second-component sealed end of the second graphite component.
2 . The method of claim 1 , wherein the graphite-based infrastructure, comprising, the carbide-containing seal, is configured to withstand a temperature of greater than 1500° C. (a) while subjected to an internal pressure of greater than 0.7 MPa produced by a molten tin flown through the first graphite component and the second graphite component and (b) while remaining monolithic with each of the first-component sealed end and the second-component sealed end and sealing the first graphite component to the second graphite component.
3 . The method of claim 1 , wherein the sealing structure, the first-component initial end, and the second-component initial end are heated to at least 2000° C.
4 . The method of claim 1 , wherein heating the sealing structure, the first-component initial end, and the second-component initial end is performed by flowing the molten metal through the first graphite component and the second graphite component.
5 . The method of claim 4 , wherein the molten metal comprises tin (Sn).
6 . The method of claim 5 , wherein the molten metal further comprises the one or more metals selected from the group consisting of titanium (Ti), zirconium (Zr), and hafnium (Hf).
7 . The method of claim 4 , further comprising forming a secondary seal between the first graphite component and the second graphite component before flowing the molten metal through the first graphite component and the second graphite component.
8 . The method of claim 7 , wherein the secondary seal is formed by a graphite sheet.
9 . The method of claim 7 , wherein the secondary seal blocks the sealing structure from contact with the molten metal.
10 . The method of claim 1 , wherein the sealing structure, the first-component initial end, and the second-component initial end are positioned in a low-oxygen environment when heated to form the carbide-containing seal.
11 . The method of claim 10 , further comprising forming the low-oxygen environment around the sealing structure, the first-component initial end, and the second-component initial end by:
sealing an enclosure to the first graphite component and the second graphite component, and
flowing an inert gas into the enclosure as well as into the first graphite component and the second graphite component.
12 . The method of claim 1 , wherein the sealing structure, the first-component initial end, and the second-component initial end are heated locally using a localized induction heater positioned proximate to the sealing structure, the first-component initial end, and the second-component initial end.
13 . The method of claim 1 , wherein the sealing structure is one of (a) a metal wire forming a ring around openings in the first graphite component and the second graphite component or (b) a metal foil having a thickness of 25-125 micrometers.
14 . The method of claim 1 , wherein the carbide-containing seal is formed by graphite fusing comprising one or more techniques selected from the group consisting of:
brazing the sealing structure with each of the first-component initial end and the second-component initial end,
reaction bonding the sealing structure with each of the first-component initial end and the second-component initial end, and
diffusion bonding the sealing structure with each of the first-component initial end and the second-component initial end.
15 . The method of claim 1 , wherein positioning the sealing structure between the first graphite component and the second graphite component is performed using a compression fixture comprising a first clamp, engaging the first graphite component, and a second clamp, engaging the second graphite component.
16 . The method of claim 15 , wherein each of the first clamp and the second clamp is formed from a refractory material.
17 . The method of claim 15 , wherein the compression fixture remains as a part of the graphite-based infrastructure.
18 . The method of claim 1 , wherein positioning the sealing structure between the first graphite component and the second graphite component comprises compressing the sealing structure between the first graphite component and the second graphite component at a pressure of 70-3,500 kPa.
19 . The method of claim 1 , further comprising:
coating interior surfaces of the first graphite component and the second graphite component with a precursor;
forming an internal carbide-containing sealing coating from the precursor.
20 . The method of claim 19 , wherein the precursor comprises one or more components selected from the group consisting of a silicon-containing polymer, graphite particles, and metal particles.