Ultrafast flash sintering method and system for performing the same

Abstract

Ultrafast Joule heating synthesis methods and systems, and more particularly, ultrafast flash Joule heating upcycling of fiber reinforced plastics (such as waste fiber reinforced plastics, glass fiber reinforced plastics, carbon fiber reinforced plastics, and / or quartz fiber reinforced plastics) and materials including fiber reinforced plastics (such as reinforced metal laminates including glass reinforced aluminum laminates and other glass reinforced metal laminates) to phase-controllable silicon carbide (SiC). Further, ultrafast Joule heating synthesis methods and systems for synthesis include SiC fibers / fibrils (such as SiC nanowires), SiC nanowires, and SiC-containing polymer composites, as well as B4C nanowires.

Description

[0001] Cross-referencing of related patent applications

[0002] This application claims priority to U.S. Patent Application Serial No. 63 / 585,465, filed September 26, 2023, entitled “Ultrafast Flash Joule Heating Synthesis Methods and Systems For Performing Same”, which is jointly owned by the owners of this invention and is incorporated herein in its entirety.

[0003] This application relates to PCT application number PCT / US21 / 52030 (“Tour '030 PCT application”), filed September 24, 2021, entitled “Ultrafast FlashJoule Heating Synthesis Methods And Systems For Performing Same”, which is jointly owned by the owners of this invention and is incorporated herein in its entirety.

[0004] This application relates to PCT International Patent Application No. PCT / US23 / 67000, filed on May 15, 2023, and attributed to JM Tour et al., entitled “Flash Joule Heating For Production of 1D Carbon And / Or Boron Nitride Materials”, which is jointly owned by all the owners of this invention and is incorporated herein in its entirety. Technical Field

[0005] This invention relates to ultrafast Joule heating synthesis methods and systems, and more specifically to ultrafast flash Joule heating upcycling of fiber-reinforced plastics (such as waste fiber-reinforced plastics, glass fiber-reinforced plastics, carbon fiber-reinforced plastics, and / or quartz fiber-reinforced plastics, or more generally mixtures of plastics and glass) and materials including fiber-reinforced plastics (such as reinforced metal laminates including glass-reinforced aluminum laminates and other glass-reinforced metal laminates) to phase-controlled silicon carbide (SiC). Further embodiments relate to ultrafast Joule heating synthesis methods and systems for synthesizing SiC fibers / fibers (such as SiC nanowires), SiC nanowires and SiC-containing polymer composites, as well as B4C nanowires.

[0006] Government interests

[0007] This invention was made with government support under grant number FA9550-22-1-0526 granted by the U.S. Air Force Office of Scientific Research and grant numbers ERDC W912HZ-21-2-0050 and W912HZ-24-2-0027 granted by the U.S. Army Corps of Engineers Research and Development Center. The U.S. government holds certain rights to this invention. Background Technology

[0008] Fiber-reinforced plastics (FRPs), with their reinforcing fibers embedded in a polymer matrix, are robust composite materials. [Goncalves 2022; Cunliffe 2003]. Glass fiber reinforced plastics (GFRPs) account for 95% of all FRPs, offering advantages such as light weight, chemical stability, and excellent mechanical properties [Cui 2020; Cheng 2022; Sena-Cruz 2020; Sathishkumar 2014], and have been widely used in a wide range of platforms, from the automotive and aerospace industries to wind turbine blades and motion equipment. Global annual demand for GFRP is estimated to exceed 6 million tonnes by 2030, with an annual growth rate of approximately 10%. [Xue 2021]. However, the lifespan of GFRP is only 10 to 40 years [Karuppannan Gopalraj 2020; Jensen 2018], resulting in the disposal of millions of tonnes of GFRP.

[0009] Currently, more than half of waste GFRP is directly landfilled, as this is considered the cheapest and simplest disposal method [Krauklis 2021; Thomason 2016]. GFRP typically comprises thermosetting plastic composites containing glass fibers, and the plastic matrix is ​​difficult to degrade by natural decomposition or microbial treatment [Zheng 2005; Bahl 2021]. Incineration [Jacob 2011; Naqvi 2018] and solvent decomposition methods [Liu 2006; Ahrens 2023] achieve the reuse of glass fibers by burning the polymer matrix or dissolving it using chemical agents such as highly concentrated acids or alkalis, and then reshaping the glass fibers.

[0010] However, polymer removal processes often result in additional greenhouse gas (GHG) emissions or solvent consumption, generating secondary waste streams. Upgrading GFRP to functional materials such as silicon carbide (SiC) represents a promising approach. SiC is a high-performance reinforced and semiconductor material with high mechanical strength, high temperature stability, high thermal conductivity, and a wide bandgap [Wang 2023]. Conventionally, SiC synthesis methods mainly include chemical vapor deposition (CVD) [Booker 2016; Clavaguera-Mora 1997], physical vapor transport (PVT) [Yan 2014; Herro 2003], and acheson carbothermal reduction (ACR) [Shin 2005; Guo 2013]. CVD and PVT methods often require specific temperature gradients and large carrier gas supplies, as well as expensive gaseous silicon and carbon precursors, such as silanes or methane [Booker 2016; Yan 2014]. For SiC synthesis via the ACR process, the precursors are more diverse, including charcoal, biomass, or silica gel [Shin 2005; Guo 2013]. However, annealing at high temperatures (>1500°C) for hours or even days is required to complete the reaction [Shin 2005; Guo 2013], resulting in high energy consumption. Waste GFRP contains both Si and C, and has the potential to serve as both Si and C sources for SiC synthesis.

[0011] Recently, direct electrothermal heating has emerged as a scalable and efficient method for materials synthesis [Jiang 2021; Cheng 2022; Liu 2020; Zhu 2023] and waste management [Wyss 2023; Yu 2023], requiring no additional solvents or catalysts. Under an electrical pulse input, samples can be rapidly heated (approximately 10... 4 ℃ s -1 ) and cooling rate (approximately 10 3 ℃ s -1 It reaches ultra-high temperatures of >3000 K, which is difficult to achieve through conventional furnace heating. At such high temperatures, carbon-containing waste can be effectively converted into crystalline graphene [Jia 2022; Luong 2020] and heavy metals can be removed [Deng I2023; Deng II 2023].

[0012] Therefore, there remains a need to develop methods for recycling fiber-reinforced plastics, especially when these reach the end of their lifespan. There also remains a need to reduce / eliminate the undesirable waste of resources and environmental pollution currently caused by landfill and incineration (the primary methods of treating fiber-reinforced plastics). Summary of the Invention

[0013] This invention relates to ultrafast Joule heating synthesis methods and systems, and more specifically to ultrafast flash Joule heating upcycling of fiber-reinforced plastics (such as waste fiber-reinforced plastics, glass fiber-reinforced plastics, carbon fiber-reinforced plastics, and / or quartz fiber-reinforced plastics, or more generally, mixtures of plastics and glass) and materials including fiber-reinforced plastics (such as reinforced metal laminates including glass-reinforced aluminum laminates and other glass-reinforced metal laminates) to phase-controlled silicon carbide (SiC). Further embodiments relate to ultrafast Joule heating synthesis methods and systems for synthesizing SiC fibers / fibers (such as SiC nanowires), SiC nanowires and SiC-containing polymer composites, as well as B4C nanowires.

[0014] Direct electric heating has emerged as a time- and energy-efficient method for materials synthesis [Yao 2018; Wang 2020; Cheng 2021; Chen 2016; Zhu 2023] and waste management [Wyss I 2023; Liu 2022; Dong 2023; Luo 2023; Jia 2022]. The applicant has previously applied flash Joule heating to the conversion of waste plastics into disordered graphene [Wyss II 2023; Luong 2020] and to add value to solid waste [Deng 2021; Deng II 2022; Deng 2023; Chen 2023]. It has been found that direct electric heating provides a rapid and energy-efficient alternative for upgrading and remanufacturing GFRP into SiC, which could potentially promote a circular economy and cleaner production. When carbothermic reduction occurs during the flash Joule heating process, the process can be referred to as flash carbothermic reduction.

[0015] Generally, embodiments of the present invention include a solvent-free and energy-efficient flash upcycling process to convert a mixture of milled glass fiber reinforced plastics and carbon fiber reinforced plastics into SiC powder within seconds and in a yield of >90%. By modulating the input pulse voltage and flash time, SiC with two different phases (3C-SiC and 6H-SiC), each with a phase purity of 90% to 99%, can be selectively synthesized. The SiC powder is further used as an anode material for lithium-ion batteries, resulting in phase-dependent performance. The 3C-SiC anode exhibits superior reversible capacity and rate performance compared to the 6H-SiC anode, while both show excellent cycle stability. Life cycle assessments reveal that the flash upcycling process demonstrates significant reductions in energy demand, greenhouse gas emissions, and water consumption compared to solvent decomposition and incineration processes. Therefore, the flash process enables the efficient, economical, and environmentally friendly conversion of waste fiber-reinforced plastics into value-added SiC materials. [Deng I 2022; Tour '030 PCT application].

[0016] Generally, in one embodiment, the present invention is characterized by a method of synthesizing materials. The method includes forming a mixture comprising one or more elemental sources and a catalyst. The method further includes using the mixture for a flash Joule heating process to form a structure selected from the group consisting of fibers, fibrils, whiskers, nanotubes, and one-dimensional structures. The flash Joule heating process includes applying a voltage across the mixture for one or more flash time periods. The product includes a material selected from the group consisting of carbides, borides, nitrides, boron nitrides, boron carbides, BNC, oxynitrides, carbonitrides, oxides, dioxides, sulfides, disulfides, selenides, diselenides, tellurides, ditellurides, phosphides, oxycarbides, oxyborides, oxynitride carbides, oxyboron nitrides, oxycarboborides, OBNC, arsenides, and antimony compounds.

[0017] Embodiments of the present invention may include one or more of the following features:

[0018] The structure may include inorganic compounds. These inorganic compounds may include a first element or compound selected from the group consisting of boron, silicon, carbon, aluminum, germanium, tin, gallium, indium, lead, copper, zinc, cadmium, magnesium, titanium, cobalt, tungsten, vanadium, hafnium, niobium, molybdenum, zirconium, tantalum, and combinations thereof. These inorganic compounds may include a second element or compound selected from the group consisting of C, B, O, N, S, P, As, Sb, Se, Te, Si, Ge, Sn, I, and combinations thereof.

[0019] The inorganic compound can be selected from the group consisting of transition metal dichalcogenides, mixed chalcogenide transition metal dichalcogenides, transition metal dichalcogenides containing more than one type of transition metal, III-V compounds, II-VI compounds, I-VII compounds, group IV compounds, group IV elements, IV-VI compounds and mixtures thereof.

[0020] Catalysts can be elements, salts, polyoxometalates, or organometallic compounds that contain group metals, transition metals, lanthanides, or actinides.

[0021] The mixture may further include growth promoters or regulators comprising elements selected from the group consisting of F, S, Se, Cl, Br, I, P, O, or N, which are added to the mixture to enhance the growth of one-dimensional structures.

[0022] Generally, in another embodiment, the present invention is characterized by a method for synthesizing silicon carbide fibers or fibrils. The method includes forming a mixture comprising a silicon source, a carbon source, and a catalyst. The method further includes performing a flash Joule heating process using the mixture to form silicon carbide fibers or fibrils. The flash Joule heating process includes applying a voltage across the mixture for one or more flash time periods.

[0023] Embodiments of the present invention may include one or more of the following features:

[0024] The silicon or carbon source can be selected from a group consisting of powder, fiber, silicone, sodium silicate, iron silicate, silicate, aluminosilicate, silicon oxide, silicon dioxide, fiber-reinforced plastic granules, silicon wafers, and waste solar panels.

[0025] The silicon or carbon source can be derived from fiber-reinforced plastic particles, which are derived from the group consisting of fiber-reinforced plastics, reinforced metal laminates, and combinations thereof.

[0026] The silicon source or carbon source can be a fiber selected from waste fiber, glass fiber, carbon fiber plastic, quartz fiber, basalt fiber, rock wool, polymer fiber, plant fiber, asbestos, rock fiber, mineral fiber and combinations thereof.

[0027] The catalyst can be a metal catalyst.

[0028] Metal catalysts may include metals selected from the group consisting of iron, nickel, cobalt, and manganese.

[0029] Metal catalysts can be made from metals selected from the group consisting of iron, nickel, cobalt, and manganese.

[0030] Metal catalysts can be metal acetylacetonates, metal salts, metal chlorides, metal nitrites, nickel calcitonides, ferrocene, metal oxides, metal acetates, metal fluorides, organometallic compounds, polyoxometalates, and combinations thereof.

[0031] The metal catalyst can be selected from the group consisting of Fe(acac)3, Ni(acac)2, Co(acac)2, ferrocene, ferrous nitrite, ferric nitrate, nickel nitrite, nickel nitrate, cobalt nitrite, cobalt nitrate, manganese nitrite, manganese acetylacetone, manganese acetate, ferric acetate, nickel acetate, cobalt acetate, ferric fluoride, nickel fluoride, cobalt fluoride, manganese fluoride, and combinations thereof.

[0032] Generally, in another embodiment, the present invention is characterized by a method for synthesizing B4C nanowires. The method includes forming a mixture comprising a boron source, a carbon source, and a catalyst. The method further includes performing a flash Joule heating process using the mixture to form B4C nanowires. The flash Joule heating process includes applying a voltage across the mixture for one or more flash time periods.

[0033] Embodiments of the present invention may include one or more of the following features:

[0034] The boron source can be selected from boric acid, boron oxide, borax, metal borates, boranes, carboranes, and combinations thereof.

[0035] The carbon source can be selected from carbon black, coke, silicone, carborane, graphite, graphene, carbon fiber, carbon nanotubes, biochar and combinations thereof.

[0036] Catalysts may include metal catalysts selected from the group consisting of metal salts, metal powders, polyoxometalates, organometallic compounds, and combinations thereof.

[0037] Metal salts can include metallic elements selected from the group consisting of Fe, Co, Ni, and Mn.

[0038] Metal salts can include metallic elements selected from the group consisting of Mo, Cr, V, Ru, Rh, and Nb.

[0039] Metal salts can be selected from the group consisting of ferric chloride (FeCl3), ferrocene, ferrous nitrite, ferric acetylacetonate (III) (Fe(acac)3), nickel acetylacetonate (II) (Ni(acac)2), cobalt acetylacetonate (II) (Co(acac)2), ferric nitrate, nickel acetylacetonate, ferric acetate, nickel acetate, cobalt acetate, manganese acetate, manganese acetylacetonate, manganese chloride, manganese chloride, ferric fluoride, cobalt fluoride, nickel fluoride, manganese fluoride, and combinations thereof.

[0040] The flash Joule heating process can be carried out using a flash power source consisting of a selectable combination of a charging capacitor, a commercial arc welding machine, a DC power supply, and other components.

[0041] The output of a flash power supply can be a current pulse or a continuous current.

[0042] B4C nanowires can have diameters ranging from 2 nm to 1 μm. B4C nanowires can have lengths ranging from 0.1 μm to 5000 μm.

[0043] Generally, in another embodiment, the present invention is characterized as a battery comprising an electrode comprising silicon carbide particles produced from fiber-reinforced plastic using any of the methods described above.

[0044] Embodiments of the present invention may include one or more of the following features:

[0045] The battery can be a lithium-ion battery.

[0046] Silicon carbide particles can be used as the negative electrode material in batteries.

[0047] Generally, in another embodiment, the invention is characterized as a method. This method includes producing silicon carbide particles from fiber-reinforced plastics using any of the methods described above. The method further includes applying the silicon carbide particles to a product selected from the group consisting of composite reinforcement, semiconductors, photocatalysis, and electrocatalysis.

[0048] Generally, in another embodiment, the invention is characterized by a method for synthesizing silicon carbide fibers or fibrils. This method includes forming a mixture comprising fibers or fiber-reinforced plastic particles and a catalyst. The method further includes using the mixture for a flash Joule heating process to form silicon carbide fibers or fibrils. The flash Joule heating process includes applying a voltage across the mixture for one or more flash time periods.

[0049] Embodiments of the present invention may include one or more of the following features:

[0050] Fiber-reinforced plastic granules can be formed from materials selected from the group consisting of fiber-reinforced plastics, reinforced metal laminates, and combinations thereof.

[0051] Fiber-reinforced plastic granules can be formed from fiber-reinforced plastics.

[0052] The steps involved in forming fiber-reinforced plastic granules include grinding the fiber-reinforced plastic.

[0053] Fiber-reinforced plastics can be selected from the group consisting of waste fiber-reinforced plastics, glass fiber-reinforced plastics, carbon fiber-reinforced plastics, quartz fiber-reinforced plastics, mixtures and combinations of plastics and glass.

[0054] Fiber-reinforced plastic granules can be formed from reinforced metal laminates.

[0055] The catalyst can be a metal catalyst.

[0056] Metal catalysts may include metals selected from the group consisting of iron, nickel, cobalt, and manganese.

[0057] Metal catalysts can be made from metals selected from the group consisting of iron, nickel, cobalt, and manganese.

[0058] Metal catalysts can be selected from the group consisting of metal acetylacetonates, metal salts, metal chlorides, metal nitrites, nickel calcitonides, ferrocene, metal oxides, metal acetates, metal fluorides, organometallic compounds, polyoxometalates, and combinations thereof.

[0059] The metal catalyst can be selected from the group consisting of Fe(acac)3, Ni(acac)2, Co(acac)2, ferrocene, ferrous nitrite, ferric nitrate, nickel nitrite, nickel nitrate, cobalt nitrite, cobalt nitrate, manganese nitrite, manganese acetylacetone, manganese acetate, ferric acetate, nickel acetate, cobalt acetate, ferric fluoride, nickel fluoride, cobalt fluoride, manganese fluoride, and combinations thereof.

[0060] Silicon carbide fibers or precursor fibers can be silicon carbide nanowires.

[0061] Generally, in another embodiment, the invention is characterized as an apparatus. The apparatus includes a container operable to receive a mixture comprising fiber-reinforced plastic particles and a metal catalyst. The apparatus further includes electrodes operable to apply voltage pulses across the mixture for one or more flash time periods to subject the mixture to a flash Joule heating process. The flash Joule heating process on the mixture results in the transformation of the mixture into silicon carbide fibers or fibrils.

[0062] Embodiments of the present invention may include one or more of the following features:

[0063] The device can be further operable to perform any of the methods described above.

[0064] Generally, in another embodiment, the present invention is characterized by a method of manufacturing a polymer composite material. The method includes forming a mixture of fiber-reinforced plastic particles. The method further includes using the mixture for a flash Joule heating process to form a silicon carbide material. The flash Joule heating process includes applying a voltage across the mixture for one or more flash time periods. The silicon carbide material is selected from the group consisting of silicon carbide particles, silicon carbide fibers, and silicon carbide fibrils. The method further includes loading 0.5 wt% to 5 wt% of the silicon carbide material into a liquid polymer matrix. The method further includes curing the liquid polymer matrix to form the polymer composite material.

[0065] Embodiments of the present invention may include one or more of the following features:

[0066] Silicon carbide materials can be SiC. Polymer composites can be SiC-polymer composites.

[0067] Silicon carbide materials can be silicon carbide fibers or fibrils. Polymer composites can be SiC fibers or fibrils-polymer composites.

[0068] Silicon carbide materials can be silicon-carbon nanowires. Polymer composites can be SiC nanowire-polymer composites.

[0069] The mixture including fiber-reinforced plastic particles may further include a first catalyst.

[0070] The curing step may include mixing a catalyst / hardener into a liquid polymer matrix loaded with silicon carbide material.

[0071] The liquid polymer matrix can be selected from the group consisting of vinyl esters, epoxy resins, polyurethanes, polyaspartic acid, bismaleimide, phthalonitrile, cyanate esters, polyesters, bismaleimide-triazine, acrylic acid, PCTG, PETG, PLA, copolyesters, PCTA, PEKK, PAEK, polycarbonate, polyester, polybenzoxazole, polyimide, aromatic polyamide, polysulfone, PTFE, PVDF, HFP, PVDF / HFP, benzoxazine, polyoxazole, PEEK, PEK, PAI, PPSU, PPS, PSU, PES, PA, PC, silicone, silicon carbide, phenolic resins, graphite, carbon fibers, boron nitride, boron nitride fibers, boron carbide, or carbon / carbon composite matrices.

[0072] The curing step may include mixing a curing agent or crosslinking agent into a liquid polymer matrix loaded with silicon carbide material. The curing agent or crosslinking agent may be methyl ethyl ketone peroxide.

[0073] The curing step may include heating a liquid polymer matrix loaded with silicon carbide material.

[0074] Generally, in another embodiment, the invention is characterized by a method for synthesizing silicon carbide particles. The method includes forming a mixture comprising fiber-reinforced plastic particles. The method further includes using the mixture to perform a flash Joule heating process to form silicon carbide particles. The flash Joule heating process includes applying a voltage across the mixture for one or more flash time periods.

[0075] Embodiments of the present invention may include one or more of the following features:

[0076] The step of forming the mixture may include forming fiber-reinforced plastic particles from materials selected from the group consisting of fiber-reinforced plastics, reinforced metal laminates, and combinations thereof.

[0077] The step of forming the mixture may include forming fiber-reinforced plastic particles from fiber-reinforced plastic.

[0078] The steps of forming the mixture may include grinding the fiber-reinforced plastic to form fiber-reinforced plastic particles.

[0079] Fiber-reinforced plastics can be selected from the group consisting of waste fiber-reinforced plastics, glass fiber-reinforced plastics, carbon fiber-reinforced plastics, quartz fiber-reinforced plastics, plastics mixed with glass, carbon mixed with glass, plastics mixed with silicon dioxide, carbon mixed with silicon dioxide, and combinations thereof.

[0080] The step of forming the mixture may include forming fiber-reinforced plastic particles from a reinforced metal laminate.

[0081] The steps of forming the mixture may include grinding the reinforced metal laminate to form fiber-reinforced plastic particles.

[0082] The flash Joule heating process can form silicon carbide particles and metal carbide particles.

[0083] The reinforced metal laminate can be a glass-reinforced metal laminate.

[0084] Glass-reinforced metal laminates can be glass-reinforced aluminum laminates.

[0085] The flash Joule heating process can form silicon carbide particles and aluminum carbide particles.

[0086] The flash Joule heating process can be performed in 10 seconds and can achieve a yield of at least 90 wt%.

[0087] The voltage applied across the mixture can be controlled by modulating the input pulse voltage and by controlling the duration of one or more flashing time periods.

[0088] Controlling the voltage applied across the mixture can control the phase purity of silicon carbide particles produced by the flash Joule heating process.

[0089] This method can produce silicon carbide particles containing 3C-SiC and 6H-SiC phases.

[0090] This method can produce silicon carbide particles with a phase purity of at least 90 wt% 3C-SiC.

[0091] This method can produce silicon carbide particles with a phase purity of 90 wt% to 99 wt% 3C-SiC.

[0092] This method can produce silicon carbide particles with a phase purity of at least 90 wt% 6H-SiC.

[0093] This method can produce silicon carbide particles with a phase purity of 90 wt% to 99 wt% 6H-SiC.

[0094] The mixture can be stirred in a reactor with electrodes while the flash Joule heating process is being carried out.

[0095] Generally, in another embodiment, the invention is characterized as an apparatus. The apparatus includes a container operable to receive a mixture comprising fiber-reinforced plastic particles. The apparatus further includes electrodes operable to apply voltage pulses across the mixture for one or more flash time periods to subject the mixture to a flash Joule heating process. The flash Joule heating process on the mixture results in the fiber-reinforced plastic particles being converted into silicon carbide particles.

[0096] Embodiments of the present invention may include one or more of the following features:

[0097] The device can be further operable to perform any of the methods described above.

[0098] Generally, in another embodiment, the invention is characterized as a method. This method includes producing silicon carbide particles from fiber-reinforced plastic using any of the methods described above. The method further includes using the silicon carbide particles as a negative electrode material for a battery.

[0099] Embodiments of the present invention may include one or more of the following features:

[0100] The battery can be a lithium-ion battery.

[0101] The use of silicon carbide particles in batteries can produce phase-dependent performance.

[0102] Generally, in another embodiment, the present invention is characterized by a battery manufactured by any of the processes described above. Attached Figure Description

[0103] Figures 1A to 1D This demonstrates how FRP can be upgraded and remanufactured into silicon carbide through flash carbothermal reduction. Figure 1A This is a schematic diagram of the FCR process used for FRP upgrade and remanufacturing. Figure 1A The illustration in Step 1 is a picture of waste GFRP and chopped carbon fiber reinforced plastic (CFRP) removed from a Dewar bottle. Figure 1A The illustration in step 2 is a picture of the sample in the quartz tube before (i) and during (ii) the FCR reaction. Figure 1B It is the current profile during the FCR process with an input voltage of 150 V and a duration of 1 s. Figure 1C It is a real-time temperature curve recorded by an infrared thermometer with input voltages of 100 V and 150 V. The temperature detection range of the thermometer is 1000℃ to 3000℃. Figure 1D The diagram shows the relationship between the Gibbs free energy change (ΔG) and temperature for different ratios of SiO2 to carbon. The horizontal dashed line represents zero ΔG.

[0104] Figures 2A to 2K This demonstrates the phase-controllable synthesis of SiC. Figure 2A The crystal structures of 3C-SiC (left) and 6H-SiC (right) are shown. Figure 2B XPS spectra of the Si 2p core levels are shown for 3C-SiC (top) and 6H-SiC (bottom). The small peak at Si-O (around 103 eV) can be attributed to slight oxidation upon exposure to air. Figure 2CThe XRD patterns of purified 3C-SiC (top) synthesized at 100 V and a single flash rate, and purified 6H-SiC (bottom) synthesized at 150 V and 10 flash rates are shown. PDF reference cards for each are 3C-SiC, 01-073-1708; 6H-SiC, 01-075-8314. Figure 2D Representative Raman spectra of purified 3C-SiC (top) and 6H-SiC (bottom) are shown. TO is the transverse optical mode. LO is the longitudinal optical mode. TA is the transverse acoustic mode. LA is the longitudinal acoustic mode. Figure 2E The Tauc diagrams of 3C-SiC (top) and 6H-SiC (bottom) are shown. Figure 2F This is an HRTEM image of 3C-SiC. Figure 2G This is a magnified HRTEM image of 3C-SiC. Figure 2H This is the SAED spectrum of 3C-SiC. Figure 2I This is an HRTEM image of 6H-SiC. Figure 2J This is a magnified HRTEM image of 6H-SiC. Figure 2K This is the SAED spectrum of 6H-SiC.

[0105] Figures 3A to 3F This demonstrates the mechanism of the SiC phase transition. Figure 3A The results show the SiC phase mass ratio relative to the input voltage under a single flash pulse. Figure 3B The results show the SiC phase mass ratio relative to the flash pulse at an input voltage of 150 V. Figures 3A to 3B The error bars represent the standard deviation (SD) of SiC compared to three parallel experiments (n=3). Data are presented as mean ± SD. Figure 3C The EPR spectra of 3C-SiC and 6H-SiC are shown. Figure 3D The temperature-vapor pressure relationship of silicon and carbon is shown. Figure 3E The formation energies of 3C-SiC and 6H-SiC with different silicon vacancy contents are shown. Figure 3F The calculated crystal structures of 3C-SiC (top) and 6H-SiC (bottom) with different Si vacancy atomic contents are shown. Dashed circles represent silicon vacancies.

[0106] Figures 4A to 4I This demonstrates the phase-dependent lithium-ion battery (LIB) performance of the SiC anode. Figure 4A The charge-discharge curves of the 3C-SiC anode under different cycles are shown. Figure 4B The charge-discharge curves of the 6H-SiC anode under different cycles are shown. Figure 4C The cycling stability of the 3C-SiC and 6H-SiC anodes at 0.2 C is shown. Figure 4D The rate capacity of the 3C-SiC anode and the 6H-SiC anode is shown. Figure 4E The CV curves of the 3C-SiC anode at different scan rates are shown. Figure 4F The CV curves of the 6H-SiC anode at different scan rates are shown. Figure 4G The Nyquist plots of the 3C-SiC and 6H-SiC anodes before cycling are shown. Figure 4H The Li content of the 3C-SiC and 6H-SiC anodes during the charging process is shown. + Diffusion coefficient. Figure 4I The full-cell LIB with 3C-SiC anode and NMC622 cathode is shown to have good cycling stability at 0.2 C.

[0107] Figure 5 A schematic diagram of a system for continuous flash upgrade and remanufacturing of FRP is shown.

[0108] Figures 6A to 6E The LCA for FRP recycling is shown. Figure 6A Material flow analysis showing solvent decomposition, incineration, and FCR processes. Figure 6B This provides a comprehensive comparison of solvent decomposition, incineration, and FCR processes. Figure 6C This shows a comparison of cumulative energy demand. Figure 6D The comparison of cumulative GHG emissions is shown. Figure 6E A techno-economic comparison is shown. The material mass flow is normalized to the consumption of GFRP (1.5 tons) and CFRP (0.75 tons) that produce 1 ton of SiC during the FCR process.

[0109] Figures 7A to 7B Showing the results of ( Figure 7A Fe-free Si sources and ( Figure 7B A scheme for synthesizing SiC using an Fe-containing Si source.

[0110] Figures 8A to 8E The yield of SiC NW is shown at different flash times. Figures 8A to 8D Display ( ) respectively Figure 8A )once;( Figure 8B ) 3 times; ( Figure 8C ) 5 times; ( Figure 8D 10 flashes in time. Figure 8E The statistical results for NW yield and diameter are displayed. The error bars in e represent the standard deviation, where N = 10.

[0111] Figures 9A to 9E SEM images of SiC NW synthesized using different catalysts are shown below: ( Figure 9A FeCl3; Figure 9B2,000 ferrocene; Figure 9C Fe(acac)3; Figure 9D Ni(acac)2; and ( Figure 9E )Co(acac)2.

[0112] Figure 9F This shows that at a catalyst loading of 1 wt%, different applications... Figures 9A to 9E The yield of SiC NW synthesized in [a specific location] under the catalyst. Error bars represent standard deviation, where N = 10.

[0113] Figures 10A to 10E The results show the SiC NW diameter and nanowire yield with different catalyst contents. Figures 10A to 10D Display respectively: ( Figure 10A 0.1 wt%; Figure 10B 0.5 wt%; Figure 10C 1 wt%; and ( Figure 10D ) 2 wt% content. Figure 10E The statistical results for NW yield and diameter are displayed. The error bars in e represent the standard deviation, where N = 10.

[0114] Figures 11A to 11C SEM images of SiC NW synthesized from GFRP, desert sand, and diatomite are shown.

[0115] Figures 12A to 12E The SiC NW synthesized from fire glass with different additives is shown. Figures 12A to 12D It shows: ( Figure 12A No additives; Figure 12B 1 wt% PTFE; Figure 12C 1 wt% NaF; and ( Figure 12D 1 wt% PVC. Figure 12E The NW yield is shown using different additives. The error bars in e represent the standard deviation, where N = 10.

[0116] Figure 12F The yields of SiC NW from fireglass with varying amounts of PTFE additives are shown. Error bars represent standard deviations, where N = 10.

[0117] Figures 13A to 13B Showing the results of ( Figure 13A ) does not contain PTFE and ( Figure 13B SEM image of SiC NW synthesized with CFA containing 1 wt% PTFE.

[0118] Figures 14A to 14B Display ( ) respectively Figure 14A ) fire glass and ( Figure 14B Magnified composite SEM image of ferrocene / ferrocene

[0119] Figure 15 Characterization of the microscale mechanical properties of Young's modulus and hardness.

[0120] Figure 16 Characterization of the microscale mechanical properties of VER composites containing SiCNW through tensile testing.

[0121] Figure 17 The stress-strain curves are shown, comparing pure VER with 1 wt%.

[0122] Figure 18 The stress-strain curves of the VER containing SiC particles are shown.

[0123] Figure 19 A schematic diagram of the thermal conductivity test setup is shown, which displays the temperature of the heat flow relative to the distance of each thermocouple from the sample along the z-axis.

[0124] Figure 20 Thermal conductivity tests of VER composites containing SiC and SiCNW are shown.

[0125] Figure 21 The nanowire yield is shown as a function of heating time.

[0126] Figure 22 The yields of B4C nanowires using different catalysts are shown.

[0127] Figures 23A to 23D SEM images of B4C nanowires with different ferrocene contents (a) 0.1 wt%, (b) 0.5 wt%, (c) 1.0 wt%, and (d) 2.5 wt% are shown.

[0128] Figures 24A to 24D The statistics show the diameters of B4C nanowires with different ferrocene contents of (a) 0.1 wt%, (b) 0.5 wt%, (c) 1.0 wt%, and (d) 2.5 wt%.

[0129] Figure 25 The nanowire yield is shown relative to the catalyst loading.

[0130] Figures 26A to 26C Characterization of B4C nanowires is shown. Figure 26A These are XRD patterns. Gr represents graphene. PDF card number: B4C, 00-006-0555. Gr, 00-056-0160. Figure 26B It is Raman spectroscopy. Figure 26C It is the B 1s XPS energy spectrum.

[0131] Figures 27A to 27C The synthesis of B4C nanowires using B powder as a boron source is shown. Figure 27A These are XRD patterns. Gr represents graphene. PDF card number: B4C, 00-006-0555. Gr, 00-056-0160. Figure 27B It is an XPS spectrum. Figure 27C It is an SEM image. Detailed Implementation

[0132] This invention relates to ultrafast Joule heating synthesis methods and systems, and more specifically to ultrafast flash Joule heating upcycling of fiber-reinforced plastics (such as waste fiber-reinforced plastics, glass fiber-reinforced plastics, carbon fiber-reinforced plastics, and / or quartz fiber-reinforced plastics, or more generally plastic plus glass) and materials including fiber-reinforced plastics (such as reinforced metal laminates including glass-reinforced aluminum laminates and other glass-reinforced metal laminates) to phase-controllable silicon carbide (SiC). Further embodiments relate to ultrafast Joule heating synthesis methods and systems for synthesizing SiC fibers / fibers (such as SiC nanowires), SiC nanowires and SiC-containing polymer composites, as well as B4C nanowires.

[0133] A flash carbothermal reduction (FCR) upcycling method has been discovered, enabling the rapid and energy-efficient upcycling of waste FPR into value-added SiC materials within 1 to 10 seconds. By modulating the flash rate parameters, 3C-SiC and 6H-SiC with phase purity greater than 90% can be selectively synthesized. When SiC is used as an anode material for lithium-ion batteries (LIBs), its phase-dependent performance has been observed, with 3C-SiC anodes exhibiting superior capacity and rate performance compared to 6H-SiC anodes. With its positive attributes of low energy consumption, low GHG emissions, solvent-free and anhydrous reaction, and scalability, the FCR method has been extended to upcycling various silicon-containing wastes, including glass. Furthermore, the phase-controllable and easily scalable SiC synthesis offers opportunities for a wider range of applications beyond batteries, such as composite reinforcement, semiconductors, photocatalysis, and electrocatalysis.

[0134] Examples include a flash carbothermal reduction (FCR) method to upcycle GFRP into SiC. (If the feedstock includes aluminum, such as a glass-reinforced aluminum laminate, aluminum carbide formation is possible). During the FCR process, an electrical pulse brings the pre-milled FRP to a high temperature of 1600°C to 2900°C. The silica in the GFRP is carbothermally reduced to SiC within seconds. By modulating the operating parameters, SiC with two different phases (i.e., 3C or 6H) can be selectively synthesized. The freshly manufactured SiC was further used as an anode material for lithium-ion batteries (LIBs), and its phase-dependent properties were investigated. Thanks to the fast reaction process and ultrafast heating and cooling rates, the FCR process exhibits significant reductions in energy consumption, GHG emissions, and solvent consumption compared to conventional GFRP recycling methods. Therefore, it provides a feasible and sustainable strategy for upcycling end-of-life FRP into value-added materials with low cost and environmental impact.

[0135] Ultra-fast upgrade and recycling of waste FRP through flash carbothermal reduction

[0136] Prior to the FCR process, waste GFRP and CFRP are ground and milled into micron-sized powder. Figure 1A Step 1 (Grinding and Mixing 101). The ground GFRP powder consists of 63 wt% amorphous SiO2 and 37 wt% polymer coating. The ground CFRP powder (mainly composed of low-crystallinity and defective carbon) retains electrical conductivity comparable to that of the initial CFRP and is therefore suitable as a conductive additive for the FCR process.

[0137] In the FCR process, a mixture of GFRP and CFRP is slightly compressed inside a quartz tube with two graphite electrodes (on each side) that are connected to an external capacitor bank. Figure 1A Step 2 (Flash Carbothermic Reduction 102). CFRP acts as both a conductive additive and a carbothermic reducing agent. During the flash process, a current pulse passes through the sample under a high-voltage input, causing the sample to reach a high temperature within milliseconds. Typically, at a 2:1 GFRP to CFRP mass ratio, the sample resistance is approximately 1.5 Ω. See Table I.

[0138] Table I

[0139] FCR parameters

[0140]

[0141] Note: The input mass is the total mass of GFRP and CFRP powders.

[0142] At an input voltage of 150 V, the maximum current passing through the sample reaches approximately 350 A within a 1 s discharge time. Figure 1BThe sample temperature profile was measured using an infrared thermometer, with ultrafast heating (approximately 10 minutes) at an input voltage of 150 V. 4 ℃ s -1 ) and cooling rate (approximately 10 3 ℃ s -1 The peak temperature was recorded as approximately 2900°C. Figure 1C (Figures 121 and 122 are for 150V and 100V respectively). At such high temperatures, SiO2 in GFRP can be carbothermally reduced to SiC, and excess carbon will be converted into flash graphene. [Feldman 1968].

[0143] Thermodynamic analysis of the carbothermic reduction of SiO2 was performed to optimize the reaction conditions. According to the graph of the Gibbs free energy change (ΔG) versus temperature, increasing the carbon / SiO2 ratio can effectively reduce the reaction temperature from about 2450℃ to about 1600℃. Figure 1D (Figures 131 and 132 are for SiO2 + 2C and SiO2 + 3C, respectively). Therefore, an excess of carbon is supplied during the FCR process to ensure complete conversion of SiO2 to SiC. By modulating the flash input voltage from 80 V to 150 V, the flash peak temperature can be adjusted within the range of 1600 °C to 2900 °C, which meets the temperature requirements for SiC synthesis.

[0144] During the FCR process, CO was identified as the main gaseous product based on gas chromatography-mass spectrometry (GC-MS), with trace amounts of CO2 and organic compounds such as acetone, hexane, benzene, and toluene. As the input GFRP / CFRP mass ratio increased, the CO / CO2 molar ratio in the FCR effluent decreased, which is consistent with... Figure 1D Consistent. The input GFRP / CFRP mass ratio is also related to the sample conductivity, where a certain amount of CFRP is required to ensure a sample conductivity suitable for the flash reaction. Specifically, the input GFRP / CFRP mass ratio can be modulated from 0.25 to 3, and the SiC content in the obtained flash product can be adjusted accordingly from 7.6 wt% to 85 wt%.

[0145] Phase-controllable synthesis of SiC

[0146] The structure of SiC varies depending on the arrangement of silicon and carbon atoms, which significantly affects its properties and performance in applications [Shen 2020]. For example, 3C-SiC has a smaller band gap, lower thermal conductivity, higher electron mobility, and higher hardness than 6H-SiC [Persson 1999; Kong 2020]. Therefore, controlling the crystal phase of SiC helps optimize its properties and enable its wide range of applications. However, phase control of SiC is challenging because the SiC phase can be affected by multiple parameters, including reaction precursors, pressure, and temperature [Shimojo 2000; Yoo 1991].

[0147] 3C-SiC has a cubic lattice structure, with one silicon atom at the body center of each unit cell and eight carbon atoms at the vertices. Figure 2A 3C-SiC structure 201. In contrast, 6H-SiC has a hexagonal structure, with carbon atoms located at hexagonal lattice sites and silicon atoms occupying interstitial lattice sites between carbon atoms. Figure 2A , 6H-SiC structure 202. [Persson 1999; Kong 2020].

[0148] During the FCR process, it was discovered that phase-controllable 3C-SiC and 6H-SiC can be selectively synthesized by modulating the flash voltage and flash time. Specifically, pure-phase 3C-SiC was synthesized by a single flash at an input voltage of 100 V, based on X-ray diffraction (XRD) patterns. Further increasing the voltage to 150 V and flashing 10 times facilitated its phase transition to 6H-SiC. Note that the diffraction peak at approximately 26° is attributed to the graphene formed within the freshly synthesized SiC powder. [Luong 2020].

[0149] In Raman spectroscopy, besides the characteristic D (approximately 1350 cm⁻¹) of flash graphene... -1 ), G (approximately 1580 cm) -1 ) and 2D (approximately 2680 cm) -1 Outside the band, representative TO (approximately 790 cm⁻¹) was observed in both 3C-SiC and 6H-SiC. -1 ) and LO (approximately 970 cm) -1 ) peak. Additional TA of 6H-SiC (approximately 505 cm⁻¹) -1 ) and LA (approximately 240 cm) -1 The peak is attributed to its higher symmetry mode than that of 3C-SiC. [Feldman 1968].

[0150] To characterize the electronic structure of the newly synthesized SiC, X-ray photoelectron spectroscopy (XPS) measurements were performed. Figure 2BUnlike the GFRP precursor, which exhibits Si-O (approximately 103 eV) and CO (approximately 288 eV) peaks, both SiC phases show distinct Si-C (approximately 100 eV) and C-Si (approximately 282 eV) peaks in the C 1s and Si 2p core level energy spectra. Figure 2B [Yu 2021].

[0151] To better compare the intrinsic properties of the two phases of SiC, the SiC sample was calcined in air at 700 °C to remove graphene. According to TGA analysis, after calcination, SiC showed negligible weight loss (<0.5 wt%) when heated to 1000 °C in air. XRD patterns of the purified SiC showed phase purities of 99% for 3C-SiC and 90% for 6H-SiC. Figure 2C The distinct TO and LO bands in the Raman spectrum ( Figure 2D ) and the Si-C bond vibration peak in the infrared spectrum (approximately 800 cm⁻¹) -1 The high purity of SiC was confirmed without any graphene or SiO2 signal [Yu 2021], thus proving that air calcination is a simple and effective method for purifying SiC.

[0152] Furthermore, diffuse reflectance UV-Vis (UV-Vis) spectra reveal different optical properties of these SiC powders, with 3C-SiC exhibiting a smaller band gap (2.45 eV) compared to 6H-SiC (2.86 eV). Figure 2E .

[0153] Morphological characterization by scanning electron microscopy (SEM) revealed that the 3C-SiC and 6H-SiC powders have similar lateral dimensions of 2 to 3 μm. Energy dispersive spectroscopy (EDS) mapping images showed uniform distribution of Si and C signals, while the O signal was negligible. High-resolution transmission electron microscopy (HRTEM) images further revealed the different atomic arrangements and lattice fringes of the two phases. Figures 2F to 2K The 0.25 nm interplanar spacing (d) corresponds to the (111) plane of 3C-SiC. Figure 2G , it is Figure 2F (Magnified HRTEM image of 3C-SiC in box 251), while d at 0.26 nm corresponds to the (010) plane of 6H-SiC ( Figure 2J , it is Figure 2I (Magnified HRTEM image of 6H-SiC in box 281). Different selected area electron diffraction (SAED) patterns further confirmed the structural differences between 3C-SiC and 6H-SiC (respectively). Figure 2H and 2KThe silicon-based yields were measured by inductively coupled plasma mass spectrometry (ICP-MS), and the yields remained high at 94% and 91% for 3C-SiC and 6H-SiC, respectively, indicating that the FCR process resulted in negligible silicon loss.

[0154] Mechanism of phase transition process

[0155] To investigate the SiC phase transition process, the comparison of SiC samples synthesized under different input voltages and flash times was calculated using XRD patterns. Figures 3A to 3B ( Figure 3A Figures 301 to 302 in the figure represent 3C-SiC and 6H-SiC, respectively; Figure 3B Figures 311 to 312 in the figure represent 3C-SiC and 6H-SiC, respectively. It was observed that increasing the input voltage and flash time led to the conversion from 3C-SiC to 6H-SiC, indicating that higher reaction temperature and longer reaction time are favorable for phase transition.

[0156] To explain the phase transition mechanism, the detailed structural features of the two phases were first characterized. Si vacancies were detected in both 3C-SiC and 6H-SiC using electron paramagnetic resonance (EPR) spectroscopy. The different EPR line shapes in 3C-SiC and 6H-SiC indicate different environments for the Si vacancies. Figure 3C (Figures 321 to 322 are 3C-SiC and 6H-SiC, respectively). [Son 2007]. The high temperatures (approximately 2900°C, 150 V) during multiple FCR processes can cause continuous evaporation of silicon atoms, contributing to a higher silicon vacancy content in 6H-SiC. Figure 3D (Figures 331 to 332 are 3C-SiC and 6H-SiC, respectively).

[0157] In addition, density functional theory (DFT) calculations were used to describe the energy landscape of the Si-C system. Figures 3E to 3F ( Figure 3E Figures 341 to 342 show 3C-SiC and 6H-SiC, respectively; crystal structures 351 to 352 are 3C-SiC with Si vacancy content of 1 at% and 10 at% respectively; crystal structures 353 to 354 are 6H-SiC with Si vacancy content of 10 at% and 15 at% respectively. This demonstrates that silicon vacancies dominate the formation energy of the Si-C phase and act as a key factor in the SiC phase transition. Figures 3E to 3F At low silicon vacancy contents (<10 at%), 3C-SiC exhibits a lower formation energy than 6H-SiC, while 6H-SiC requires higher silicon vacancy contents (>10 at%). Figures 3E to 3FThermodynamically more stable at lower silicon vacancy contents. When further considering the possible dual silicon vacancies in SiC, the trend of phase-dependent formation energy is similar, with 3C-SiC being more stable at lower silicon vacancy contents and 6H-SiC being more stable at higher silicon vacancy contents.

[0158] It is worth noting that conventional carbothermal reduction processes (which involve reaction times ranging from hours to days [Shin 2005; Guo 2013]) are not conducive to SiC phase control. In contrast, in this FCR process, phase controllability is achieved thanks to ultrafast heating and cooling rates and precise energy input, which allows for the selective synthesis of 3C-SiC and 6H-SiC.

[0159] LIB performance of SiC-based anode materials

[0160] SiC, with its Si–C bilayer stacked structure, provides ideal space for lithium-ion intercalation and is considered a potential anode material for lithium-ion batteries (LIBs). [Sun 2020; Li 2016; Yu 2022]. The electrochemical properties of SiC, including carrier density, electronic conductivity, and ion diffusion performance, are highly dependent on its phase. [Shen 2020; Kong 2020]. Therefore, phase control is important for the performance of SiC anodes in LIBs.

[0161] First, SiC synthesized via FCR with graphene residues and calcined bare SiC were used as the negative electrode in a coin cell, with a lithium chip serving as the counter electrode. It was observed that the inclusion of graphene in the negative electrode improved its performance, with an optimal SiC ratio of approximately 60 wt%. This improvement in negative electrode performance can be attributed to the enhanced carrier density and better conductivity of SiC in the presence of graphene, as confirmed by simulated density of states (DOS) banding and electrochemical impedance spectroscopy.

[0162] The battery performance of 3C-SiC and 6H-SiC anodes was further compared. Long-term constant current discharge-charge cycle results revealed that both 3C-SiC and 6H-SiC anodes could maintain stable capacity after 200 cycles, with a capacity loss of approximately 5%. Figures 4A to 4C ( Figure 4A Figures 401 to 404 in the diagram represent the 1st, 10th, 100th, and 200th cycles, respectively. Figure 4B Figures 411 to 414 in the figure represent the 1st, 10th, 100th, and 200th cycles, respectively; Figure 4C Figures 421 to 422 show the specific capacities of the 3C-SiC and 6H-SiC anodes, respectively; and Figure 4C Figures 423 to 424 show the coulombic efficiencies of the 3C-SiC and 6H-SiC anodes, respectively. However, the 3C-SiC anode exhibits a coulombic efficiency of 741 mAh·g after 200 cycles.-1 Its superior capacity is greater than that of 6H-SiC (626 mAh·g). -1 The specific capacity of the 3C-SiC anode is approximately 16% higher. The average specific capacities at rate factors of 0.1 C, 0.2 C, 0.4 C, 0.8 C, and 1.6 C are 781, 765, 679, 550, and 309 mAh·g, respectively. -1 All of these exhibit enhanced performance compared to the 6H-SiC anode. Figure 4D Table II. (In Figure 4D Points 431a to 431f show the rate capacity of the 3C-SiC anode at different scan rates, and points 432a to 432f show the rate capacity of the 6H-SiC anode at different scan rates. When using a cycling rate of 0.4 C, the 3C-SiC anode exhibits 82% capacity retention after 200 cycles, which is higher than that of the 6H-SiC anode (71%).

[0163] Table II

[0164] Specific capacity of SiC-based anodes at different cycle rates

[0165]

[0166] Note: The retention rate of the negative electrode capacity is calculated by the ratio between the average capacity at a certain cycle rate and the average capacity at 0.1 C.

[0167] After cycling, the solid electrolyte interphase (SEI) layer continuously and uniformly covers the surface of the SiC anode. As confirmed by XRD patterns and XPS energy dispersive spectroscopy, the phase, structure, and crystallinity of SiC were maintained, demonstrating the excellent stability of SiC as a LIB anode material.

[0168] The mechanism of the phase-dependent LIB performance of SiC was further investigated. First, as shown by Brunauer–Emmett–Teller (BET) characterization, the two phases of SiC powder have comparable specific surface areas. This eliminates the interference of specific surface area and pore size distribution on its LIB performance. Further ICP-MS results showed that the content of trace metal impurities (especially Fe, Ni, Co, Mn and Li) in both 3C-SiC and 6H-SiC is far below 50 ppm, thus avoiding their negative impact on the anode performance. [Li2023; Chen 2023].

[0169] Second, cyclic voltammetry (CV) was performed to evaluate Li + Diffusion kinetics. For both 3C-SiC and 6H-SiC anodes, the irreversible lithiation peak at approximately 0.8 V in the first scan is related to SEI formation, corresponding to... Figures 4A to 4BThe discharge plateau was observed. After the first cycle scan, with further increases in the potential scan rate, all CV curves exhibited similar shapes during the lithiation / delithiation process, indicating reversible Li-ionization. + Insertion and extraction, as well as small polarization. Figures 4E to 4F ( Figure 4E Figures 441 to 446 in the figure represent values ​​of 0.1 mV / s, 0.5 mV / s, 1.0 mV / s, 2.0 mV / s, 5.0 mV / s, and 10.0 mV / s, respectively; and Figure 4F Figures 451 to 456 in the figure represent values ​​of 0.1 mV / s, 0.5 mV / s, 1.0 mV / s, 2.0 mV / s, 5.0 mV / s, and 10.0 mV / s, respectively.

[0170] Generally speaking, Li + Storage mainly consists of two parts: a diffusion-controlled Faraday reaction process and a surface-induced capacitance process. The contributions of these two processes can be expressed by the equation i = av. b The calculation is performed, where i is the current, v is the scan rate, and a and b are adjustable constants [Qian 2018]. Here, b can be used to describe various reaction kinetics during the ion storage process, calculated from the slope of log(i) relative to log(v), which is approximately 0.5 for both 3C-SiC and 6H-SiC anodes. This indicates that Li + The diffusion process is the dominant process in SiC anodes. [Chen 2015].

[0171] Third, EIS spectroscopy reveals that it is related to the 6H-SiC anode (R ct Compared to 181 Ω, the 3C-SiC anode has a lower charge transfer resistance (RΩ). ct = 139 Ω, corresponding to the semicircle of high to mid frequencies ( Figure 4G Figures 461 to 462 (showing the 3C-SiC and 6H-SiC anodes respectively) demonstrate the higher charge transfer rate of the 3C-SiC anode [Kim 2018]. The slope in the low-frequency region is related to Li... + This is related to the diffusion process. The higher slope of the 3C-SiC anode indicates its higher Li content. + Diffusion efficiency. Figure 4G After 100 and 200 cycles, the EIS curves showed lower charge transfer resistance and a lower slope in the low-frequency region, indicating improved charge transfer behavior after cycling. However, Li... + The diffusion efficiency decreases. Therefore, the EIS results confirm that Li... + Diffusion is the dominant process in SiC anodes, which is consistent with the CV results.

[0172] Finally, the diffusion coefficient of the SiC anode was quantitatively measured using galvanostatic intermittent titration (GITT) [Chen 2023; Yang 2018]. Based on Fick's second law, the Li- ionization coefficient of 3C-SiC and 6H-SiC anode materials was measured using galvanostatic intermittent titration (GITT). + Diffusion coefficient (D) Li + During testing, representative GITT curves were measured under cyclic conditions at 0.1 C, with the duration (τ) of each current pulse set to 1800 s and the relaxation time after each pulse set to 7200 s. Voltage was recorded every 1 second.

[0173] During the discharge process, the potential initially drops rapidly, which can be attributed to the internal resistance of the electrodes. Subsequently, due to the electrochemical Li during constant current discharge... + Upon deintercalation, the rate of potential decrease slows. After each current pulse, the potential immediately increases due to internal resistance. Eventually, it gradually reaches a quasi-equilibrium open-circuit potential. [Chen 2023; Sun 2020].

[0174] Then D Li + It can be calculated as shown in equation (1):

[0175]

[0176] Among them, D Li + (cm 2 s −1 ) is Li + The chemical diffusion coefficient; τ is the duration (s) of the current pulse. B V is the number of moles (mol) of active material. B (cm 3 mol −1 S (cm³) is the molar volume; 2 ) is the apparent area of ​​the electrode; τ(s) is the pulse time; ΔE τ (V) is the potential change during a single step of the current pulse; ΔE s (V) represents the steady-state potential change between steps.

[0177] The 3C-SiC anode exhibits higher Li content than the 6H-SiC anode at different voltages. + The diffusion coefficient increases by an average of 31% and 26% during charging and discharging, respectively. Figure 4H (Figures 471 and 472 show the 3C-SiC and 6H-SiC anodes, respectively). These findings support the view that the enhanced performance of the 3C-SiC anode is due to improved Li...+ Caused by diffusion.

[0178] Based on its excellent half-cell performance, 3C-SiC anodes are further used as anodes in full cells, with commercially available NMC622 (LiNi) being developed. 0.6 Mn 0.2 Co 0.2 O2) is the positive electrode. After 200 cycles, the full battery capacity can maintain a high value of 2.39 mAh, and the capacity is maintained at 82%. Figure 4I Figures 481 to 482 show the capacity and coulombic efficiency, respectively, where the areal capacity is calculated as 1.55 mAh cm⁻¹. -2 This indicates that the rapidly upgraded SiC anode material shows promise as an anode material for high-performance rechargeable batteries.

[0179] Scalability display

[0180] The FCR method exhibits good scalability. Upgrading and remanufacturing of FRP and phase control of SiC primarily depend on the flash peak temperature and flash duration. Therefore, temperature control is expected to be a factor for the scale-up process.

[0181] Preliminary analysis reveals that increasing the flash voltage and capacitance of the FCR system can improve batch productivity. The FCR process can be scaled up to higher product yields, as demonstrated in Deng 2021. The theoretical feasibility of scale-up was first analyzed, and then the scalability of the process was confirmed by successfully producing gram-level samples in a batch process.

[0182] Theoretical analysis of the scale-up rules of FCR process

[0183] For FRP upgrade and remanufacturing processes, the conversion from silicon dioxide to silicon carbide and its phase transition depend on the maximum flash temperature and flash time. Figure 1D ; Figures 3A to 3F Therefore, the flash temperature on the sample is important when scaled up. For the Joule heating process, the heat (Q) is calculated using equation (2).

[0184]

[0185] Where I is the current flowing through the sample, R is the sample resistance, and t is the discharge time. The heat per volume (Q) v )Calculated using equation (3),

[0186]

[0187] Where j is the current density, and ρ e It refers to resistivity. For a specific sample, the resistivity (ρ) e () is constant.

[0188] The temperature difference (ΔT) is proportional to the heat according to equation (4).

[0189]

[0190] Where C p Let m be the heat capacity and m be the mass of the sample. Equation (4) can be reformulated per volume as equation (5).

[0191]

[0192] Where ρ m It is the density of the sample. For a specific sample, C p and ρ m Constant; therefore, Q remains constant. v It is proportional to ΔT.

[0193] The charge (q) in the capacitor bank can be calculated using equation (6).

[0194]

[0195] Where C is the capacitance of the capacitor bank and V is the voltage of the capacitor bank. Assuming all charges in the capacitor bank discharge within time t, the current density (j) can be calculated according to equation (7).

[0196]

[0197] Where S is the cross-sectional area of ​​the sample. Since we usually use cylindrical samples, the mass (m) can be calculated according to equation (8).

[0198]

[0199] Where ρ m Here, S is the sample density, S is the sample cross-sectional area, and L is the sample length. For a specific sample type, the density (ρ) is... m Keep them the same.

[0200] In summary, the current density is determined by the following equation (9).

[0201]

[0202] Therefore, ΔT can be calculated according to the following equation (10).

[0203]

[0204] Based on the above calculations, it is necessary to increase the sample mass (m) and maintain a constant temperature difference (ΔT) to scale up the FCR process. This can be achieved through two approaches: (1) increasing the input flash voltage (V), and / or (2) increasing the capacitance (C) of the FCR system.

[0205] Each batch is magnified to the gram level.

[0206] In the first-generation flash setup, a capacitor bank consisting of 10 aluminum electrolytic capacitors (450 V, 6 mF, Mouser #80-PEH200YX460BQU2) was used, with a total capacitance C0 = 60 mF. In smaller-scale experiments, an input flash voltage (V0) of 100 V and a capacitance of 60 mF were used for a sample mass of m0 = 0.30 g.

[0207] Subsequently, a second-generation FCR system with a larger capacitance (C = 0.624 F) was developed. Based on the second-generation flash setup, an input quality of FCR process scaled up to m1 = 10 g was demonstrated. Therefore, the formula for equation (11) was obtained.

[0208]

[0209] For a mass of m1 = 10 g and C1 = 0.624 F, a flash voltage of V1 = 300 V is used, consistent with equation (11). The peak temperature during this flash process is approximately 2000 °C, which is similar to the low-batch flash temperature ( Figure 1C This is similar to the effect of amplification, which proves the efficiency of the amplification.

[0210] With an input voltage of 300 V, the sample temperature can be raised to 2000 °C, and 10 g SiC per batch can be synthesized within 5 seconds. The FCR process can potentially be integrated into continuous feeding systems, enabling continuous upgrading and remanufacturing of FRP, such as from... Figure 5 The system 500 shown is illustrated in the diagram. In system 500, a sheet metal strip 501 is used to convert a milled FCR precursor (such as an FCR precursor prepared by milling waste GFRP 502a and / or waste CFRP 502 using a milling machine 503). A scraper 504 can be used to control the thickness and density of the precursor. During FCR, the sheet metal strip 501 and another conductive post are connected as two electrodes 505 to an external power supply 506. The entire system can be set up in a vacuum or inert gas-filled chamber (in the FCR zone 507) to avoid oxidation of the freshly synthesized SiC 508.

[0211] Furthermore, the flash process is undergoing scale-up for graphene synthesis, on track to a production rate of several tons per day (by 2024). [Luong 2020]. This capability can be readily used for FRP upgrade and remanufacturing purposes.

[0212] Life cycle assessment and techno-economic analysis

[0213] A comparative cradle-to-gate life cycle assessment (LCA) was conducted to compare the environmental impact and energy requirements of FCR upgrade and remanufacturing processes with other FRP treatment pathways.

[0214] This study, following the requirements of ISO 14044 (Life Cycle Assessment – ​​Requirements and Guidance (ISO 14044:2006)), aims to compare current FRP recycling processes (such as solvent decomposition [Liu 2006] and incineration [Dong 2019; Xue 2021]) with FCR-upgrading of GFRP to SiC. The objective of the assessment is to determine whether the FCR strategy results in reduced GHG emissions and energy consumption.

[0215] Scenario description and system boundary

[0216] Three scenarios were considered in the study. Figure 6A Table III. In each scenario, the lifetime of 1 ton of silicon carbide was used as a baseline, and all other material flows were normalized to the consumption of GFRP (1.5 tonnes) and CFRP (0.75 tonnes) for producing 1 tonne of SiC during the FCR process.

[0217] Table III

[0218] Material flow in various scenarios

[0219]

[0220] Note: a Material mass flow is normalized to the consumption of GFRP (1.5 tons) and CFRP (0.75 tons) for producing 1 ton of SiC during the FCR process. b GFRP, glass fiber reinforced plastic; CFRP, carbon fiber reinforced plastic; FCR, flash carbothermal reduction.

[0221] Scenario 1 Solvent Decomposition: In this prior art solvent decomposition scenario 601, GFRP (1.5 tonnes) and CFRP (0.75 tonnes) are immersed in 112.5 tonnes of 6 M nitric acid (33 wt% concentrated nitric acid - 67 wt% water) to dissolve the polymer matrix in a 60°C water bath for 5 hours [Liu 2006]. The recovered FRP (1.5 tonnes) is then washed three times with 1.5 tonnes of acetone in a stirrer (200 rpm). This process consumes 37.5 tonnes of concentrated nitric acid, 75 tonnes of water, and 1.5 tonnes of acetone. The solvents can be recovered, with assumed recoveries of 98% nitric acid and 95% acetone (although the recovery process is not described herein).

[0222] Scenario 2 Incineration: For existing incineration technology Scenario 602, GFRP (1.5 tons) and CFRP (0.5 tons) are incinerated. Afterwards, the remaining ash (1 ton, mainly silica) is purified and reshaped.

[0223] Scenario 3: FCR Upgrade and Remanufacturing Process: An example of using 3C-SiC as the output upgraded and remanufactured product during the FCR process 603 disclosed in this paper. Waste GFRP (1.5 tons) and CFRP (0.75 tons) are mixed and then ground into powder. 3C-SiC (1 ton) is synthesized by the FCR process.

[0224] Lifecycle List

[0225] Table IV summarizes the environmental impacts of material production, processing, solvent decomposition, incineration, and FCR processes, including energy consumption requirements and GHG emissions. The values ​​are explained below. Note that, based on the Argonne Green model, 1 MJ of electricity produces 0.13 kg of GHG.

[0226] Table IV

[0227] Lifecycle List

[0228]

[0229] Note: a Environmental impact or energy demand is normalized to the consumption of GFRP (1.5 tonnes) and CFRP (0.75 tonnes) for producing 1 tonne of SiC during the FCR process. b GFRP (Glass Fiber Reinforced Plastic); CFRP (Carbon Fiber Reinforced Plastic); FCR (Flash Carbothermal Reduction); GHG (Greenhouse Gas).

[0230] Materials produced: Nitric acid (1961.8 kg / ton) -1 10366 MJ tons -1 4586.9 kg tons -1 ) and acetone (2548 kg tons) -165,000 MJ tons -1 The GHG emissions, energy consumption, and water consumption (0) are derived from the Argonne GREET model.

[0231] Processing-Mixing: Based on the energy input required for the mixing process (including the mixing of milled GFRP and CFRP for FCR, and the mixing of silica and carbon powder for thermal reduction). Assuming the use of an electric powder mixer. 9 The energy consumption for mixing is 9.43 MJ / ton. -1 Accordingly, 1.23 kg tonnes were emitted during the mixing process. -1 GHG.

[0232] Processing-Grinding: GFRP and CFRP need to be ground into powder before FCR. Based on data from the literature [Den 2018], the energy input is assumed to be 270 MJ / ton. -1 The mixing process is assumed to involve 35.1 kg tons. -1 GHG emissions. The total blending and grinding energy demand and GHG emissions of CFRP and GFRP are calculated to be 279.4 MJ / tonne. -1 and 36.3 kg tons -1 As listed in Table IV.

[0233] Processing - FCR: The energy consumption for FJH synthesis of 3C-SiC powder is estimated to be 1000 MJ / ton. -1 The energy consumption of the flash upgrade and remanufacturing process is calculated using equation (12).

[0234]

[0235] Where E is the energy consumed per gram (kJ / g) -1 V1 and V2 are the voltages before and after the flash, respectively. C is the capacitance (C = 60 mF), n is the number of flashes, and M is the mass of each batch.

[0236] For the experiment synthesizing 3C-SiC with V1 = 100 V, V2 = 0 V, M = 0.3 g and n = 1, the energy consumption was calculated to be: E = 1.0 kJ g -1 = 0.28 kWh kg -1 .

[0237] For the experiment synthesizing 6H-SiC with V1 = 150 V, V2 = 0 V, M = 0.3 g and n = 10, the energy consumption was calculated to be: E = 22.5 kJ g -1 = 6.25 kWh kg-1

[0238] Considering the current industrial electricity price in Texas, USA, is $0.0587 kWh, the cost of upgrading and regenerating 1 kg of waste FRP into SiC can be estimated as: P = $0.016 to 0.37 kg. -1 .

[0239] based on Figure 1D The chemical equations used in the calculations yielded GHG, and the calculated GHG emissions were 337.56 kg tonnes. -1 .

[0240] Processing – Acid Dissolution: 1 ton of waste FRP immersed in 50 tons of 6 M nitric acid requires heating in a 60°C water bath for 5 hours. An industrial washing tank with a power of 1.2 kW is used (see reference). 10 Energy consumption was 21.6 MJ / ton. -1 Accordingly, 2.81 kg tons were emitted during this process. -1 GHG.

[0241] Processing – Acetone Washing: Assuming the use of a power source of 0.4 kW and a flow rate of approximately 0.5 m³ / s. 3 The tank and an industrial agitator with a 1-hour operating time were used for acetone washing. Energy consumption was calculated to be 0.8 kWh / ton. -1 Or 2.88 MJ tons -1 .

[0242] Processing – Incineration: According to data from the literature, the GHG emissions from CFRP and GFRP during the incineration process are 3390 and 1120 MJ tons, respectively. -1 [Dong 2018; Xue 2021]. Meanwhile, considering that incineration is an exothermic process, the energy consumption during this process is close to zero.

[0243] Processing – Purification and Remodeling: Using the Argonne Green model, GHG emissions, energy consumption, and water consumption during the purification and remodeling process are 4654.4 kg tonnes. -1 85,000 MJ tons -1 and 12.19 kg tons -1 .

[0244] Life cycle impact assessment

[0245] In this paper, environmental impact is divided into three midpoint indicators, including energy demand (Table V), GHG emissions (Table VI), and water consumption (Table VII).

[0246] Table V

[0247] Cumulative energy demand in various scenarios

[0248]

[0249] Note: a Material mass flow is normalized to the consumption of GFRP (1.5 tons) and CFRP (0.75 tons) for producing 1 ton of SiC during the FCR process. b GFRP, glass fiber reinforced plastic; CFRP, carbon fiber reinforced plastic; FCR, flash carbothermal reduction.

[0250] Table VI

[0251] Cumulative GHG emissions in various scenarios

[0252]

[0253] Note: a Material mass flow is normalized to the consumption of GFRP (1.5 tons) and CFRP (0.75 tons) for producing 1 ton of SiC during the FCR process. b GFRP (Glass Fiber Reinforced Plastic); CFRP (Carbon Fiber Reinforced Plastic); FCR (Flash Carbothermal Reduction); GHG (Greenhouse Gas).

[0254] Supplementary Table VII

[0255] Cumulative water consumption (CWU) in various scenarios

[0256]

[0257] Note: a Material mass flow is normalized to the consumption of GFRP (1.5 tons) and CFRP (0.75 tons) for producing 1 ton of SiC during the FCR process.

[0258] Cost assessment

[0259] In this article, the cost of raw materials is derived from the current prices of commercial products, including concentrated nitric acid ($30,000 tons). -1 ), water ($0.5 tons) -1 ), acetone ($1000 tons) -1 The current energy consumption cost is calculated based on the industrial electricity price in Texas, USA ($0.0587 kWh). -1 (U.S. Energy Information Administration). Values ​​are listed in Table VIII. Calculate material costs and energy costs, as shown in Table IX. Operating costs are calculated as the sum of material and energy costs, excluding labor costs within operating expenses.

[0260] Table VIII

[0261] List of materials and energy costs

[0262]

[0263] Note: a Material mass flow is normalized to the consumption of GFRP (1.5 tons) and CFRP (0.75 tons) for producing 1 ton of SiC during the FCR process. b Assume the energy consumed comes from electricity, and the price of industrial electricity in Texas, USA, is $0.0587 kWh.

[0264] Table IX

[0265] Cost assessment in various scenarios

[0266]

[0267] Note: a Material mass flow is normalized to the consumption of GFRP (1.5 tons) and CFRP (0.75 tons) for producing 1 ton of SiC during the FCR process.

[0268] Sensitivity and uncertainty

[0269] Due to the availability of data from different sources, there are some uncertainties related to the energy requirements, GHG emissions, and water consumption values ​​of the materials used in this paper.

[0270] Three scenarios were considered ( Figure 6A ), namely solvent decomposition 601 (the polymer matrix of GFRP and CFRP is dissolved by solvent), incineration 602 (GFRP and CFRP are incinerated and the ash is reshaped into fibers), and FCR process 603 (GFRP and CFRP are upgraded and regenerated into SiC powder through FCR process, and 3C-SiC is used as an example of output product).

[0271] Three environmental impacts were analyzed: energy demand, GHG emissions, and water consumption. Thanks to its ultra-short reaction time and high energy efficiency, the FCR process demonstrated significant reductions in energy consumption, GHG emissions, and water consumption. Figure 6B (Regions 611 to 613 refer to solvent decomposition, incineration, and FCR processes, respectively). Specifically, the FCR process exhibits a power output of 2879 MJ / ton. -1 Its low cumulative energy demand is about 77% and 96% lower than that of solvent decomposition and incineration recycling processes, respectively. Figure 6C Table V (in) Figure 6C In this section, item 622 shows the cumulative energy demand for solvent decomposition materials, and items 621a to 621b show the cumulative energy demand for incineration and FCR processes, respectively.

[0272] The FCR process also demonstrated 1709 kg / ton. -1 The cumulative GHG emissions are related to the solvent decomposition process (1669 kg / ton). -1 It is comparable to, and about 81% lower than, incineration. Figure 6D Table VI. (In Figure 6D In Table VII, item 632 shows the cumulative GHG emissions from solvent decomposition of materials, and items 631a to 631b show the cumulative GHG emissions from incineration and FCR processes, respectively. Both the FCR and incineration processes show very low cumulative water consumption, while the solvent decomposition process requires a large amount of water. The cost of FCR is as low as $0.047 kg when synthesizing 1 kg of SiC. -1 These represent approximately 0.2% and 3.4% of the corresponding amount of waste FRP recycled through solvent decomposition and incineration processes, respectively. Figure 6E Tables VIII-IX. (In Figure 6E In the table, item 642 shows the operating cost of solvent decomposition of materials, and items 641a to 641b show the operating costs of incineration and FCR processes, respectively.

[0273] Then, the FCR process was compared with conventional SiC synthesis processes such as CVD and ACR. Generally, CVD processes require expensive gaseous precursors, and the SiC deposition rate is approximately 10 μm / h. -1 Silicon utilization is low (<0.1%, Table X). [Booker 2016; Clavaguera-Mora 1997].

[0274] Table X

[0275] Comparison of different SiC synthesis methods

[0276]

[0277] A wider variety of precursors can be used for SiC synthesis using carbothermal reduction methods. However, conventional ACR processes always last for hours, resulting in significant energy consumption. [Shin 2005; Guo 2013] In contrast, FCR processes last only a few seconds at higher temperatures (2000°C to 3000°C). The FCR reaction time is three to four orders of magnitude shorter than other SiC synthesis processes. (Table X). These findings demonstrate the great potential of FCR as an economical and environmentally friendly process for FRP upcycling and SiC synthesis.

[0278] SiC fiber / fiber

[0279] Embodiments of the present invention further include adding a metal catalyst to the method to obtain SiC fibers and / or protofibrils. For the growth of SiC nanowires (SiC NW) via flash Joule heating, the primary method involves using an Fe-free Si source (…). Figure 7A ) and Fe-containing Si sources ( Figure 7B There are two technical approaches. It should be noted that if graphene does not affect further applications, the final calcination step is not required.

[0280] Fe-free Si source

[0281] Table XI shows the parameters used for an example of flash synthesis of SiC nanowires using an Fe-free Si source.

[0282] Table XI

[0283] Parameters for the flash synthesis of SiC nanowires using an Fe-free Si source

[0284]

[0285] Note: Each flash lasts for 1 second. The mass ratio of the Si source to the C source is 2:1.

[0286] For example, Fe-free Si sources utilized include silica powder, silica gel, sand, diatomaceous earth, and glass fiber reinforced plastic (GFRP), where the carbon source can be carbon black, metallurgical coke, biochar, or chopped carbon fibers. To enhance complete reaction between Si and the carbon source, these precursors can be milled to a size of a few micrometers (or even smaller), for example, by using a planetary ball mill (MSE Supplies, PMV1-0.4L). Catalysts can be metal salts, and in examples primarily include at least one of the following metallic elements: Fe, Co, and Ni. Other metals, such as Mo, Cr, V, Ru, Rh, and Nb, may also be able to catalyze nanowire growth. Ferric chloride (FeCl3), ferrocene, iron(III) acetylacetonate (Fe(acac)3), nickel(II) acetylacetonate (Ni(acac)2), and cobalt(II) acetylacetonate (Co(acac)2) have been used as catalysts for SiC NW synthesis.

[0287] For catalyst loading, a solvent is typically used to uniformly load the catalytic metal ions onto the precursor surface. Experimentally, 5 mg to 50 mg of metal salt is dissolved in 10 mL of ethanol, resulting in a concentration of 0.01 g / mL. -1 Up to 0.05 g mL -1Next, a mixture of 1 g of Si and C source was added to the ethanol solution and immersed in an ultrasonic bath (Cole-Parmer ultrasonic cleaner) for 15 minutes. The mixture was then dried overnight in a vacuum desiccator to ensure uniform loading of the metal catalyst. Thus, the catalyst loading could be calculated to be 0.5 wt% to 5 wt%. For large-scale catalyst loading, 0.25 g to 2.5 g of catalyst was mixed with 50 g of Si and C source for 3 hours using a planetary ball mill (MSESupplies, PMV1-0.4L) at 400 rpm.

[0288] During the nanowire synthesis process, 300 mg of dried precursor loaded with catalyst was loaded into a quartz tube with an inner diameter (ID) of 8 mm and an outer diameter (OD) of 12 mm, and two graphite electrodes (on each side). The tube was loaded onto a fixture and connected to an external flash power system. The sample was sealed in a vacuum desiccator at approximately 10 mmHg to facilitate the degassing of volatiles. A capacitor bank (60 mF) was charged by an AC power supply and output DC pulses. The maximum voltage of the capacitor bank could reach 400 V. A relay with a programmable delay time (with millisecond-level controllability) was used to control the discharge time. The input voltage was modulated from 0 to 150 V, and the discharge time was periodically set to 1 s. To ensure sufficient growth time for the nanowires, multiple electrical pulse inputs (>3 times) were typically required.

[0289] In some experiments, silica powder (SiO2, Millipore-Sigma, particle size approximately 50 nm) and carbon black (Cabot, Black Pearls 2000, average diameter approximately 10 nm) were used as representative Si and carbon sources. The yield of SiC nanowires at different flash times was investigated with a ferrocene catalyst content of 1 wt%. The nanowire yield gradually increased to 63% as the number of flashes increased from 1 to 5. Figures 8A to 8E ( Figure 8E Figures 841 to 842 in the figure represent diameter and nanowire yield, respectively. Further increasing the flash time did not show a significant effect on the yield.

[0290] Different catalysts, including several FeCl3, ferrocene, Fe(acac)3, Ni(acac)2, and Co(acac)2, were compared. It was found that Fe contributed better catalytic performance than Ni and Co, and that ferrocene and Fe(acac)3 could contribute to better NW yields than FeCl3. Figures 9A to 9F .

[0291] Ferrocene was used as a catalyst, and the catalyst concentration was adjusted. It was found that higher catalyst loading was beneficial in increasing the yield of NW in the flash products and leading to an increase in NW diameter. Figures 10A to 10E ( Figure 10E Figures 1041 to 1042 in the figure represent diameter and nanowire yield, respectively. Figure 8E and 10E The results show that the diameter grew to approximately 100 nm in five flashes. Furthermore, the aspect ratio of the nanowires (NWs) can be at least 3:1. It was also found that the nanowire yield and diameter both increased with increasing catalyst concentration. Higher catalyst concentrations can increase the NW diameter, and longer heating times generally increase the aspect ratio (longer length). Therefore, the aspect ratio can be adjusted / controlled by the growth duration, catalyst concentration, power input (temperature versus time curve), and their combinations. This allows NWs to be grown to larger diameters and longer lengths.

[0292] A series of characterizations were performed to confirm that the newly synthesized nanowires (NWs) were SiC. Clear SiC and graphene signals were observed in both XRD and Raman spectra. In TEM images, some Fe particles were observed at the ends of the nanowires, indicating their catalytic role in the growth of the SiC NWs.

[0293] Flash graphene was removed from the SiC NW product using an optional calcination method. Based on thermogravimetric analysis (TGA) results, the flash-synthesized sample was calcined in air at 700 °C for 1 hour. (TGA was performed in a 100 mL min⁻¹ air stream at a heating rate of 10 °C min⁻¹). 1 The NW retained its original structure, and no carbon peaks were observed in the Raman spectrum and XRD pattern.

[0294] GFRP, ground desert sand, and diatomaceous earth have also been used as Si sources. See also Figures 11A to 11C SEM images of SiC NW synthesized from GFRP, desert sand, and diatomite are shown.

[0295] Fe-containing Si source

[0296] Table XII shows the parameters used for an example of flash synthesis of SiC nanowires using an Fe-containing Si source.

[0297] Table XII

[0298] Parameters used for the flash synthesis of SiC nanowires using an Fe-containing Si source

[0299]

[0300] Note: Fire glass (FG); fly ash (CFA). Each flash lasts for 1 second.

[0301] For example, fire glass and fly ash (CFA) were used for the Fe-containing Si source. X-ray fluorescence spectroscopy (XRF) was used to confirm that the Fe content was 5.3 at% and 6.6 wt% for fire glass and CFA, respectively.

[0302] After grinding, the nanowire yield is often low (<30%) when directly mixed with carbon black and flash-flashed, due to the low catalytic activity of Fe2O3 in the fire glass. NW growth is typically based on a gas-liquid-solid (VLS) mechanism, where the volatilization of Fe compounds and the size of the Fe catalyst affect its catalytic performance. Therefore, halogenated additives (including polytetrafluoroethylene (PTFE), sodium fluoride (NaF), and polyvinyl chloride (PVC)) were added at 1 wt% to activate the inherent Fe in the fire glass.

[0303] It has been found that all of these halogen-containing additives can benefit NW synthesis, and PTFE achieved an optimal NW yield of more than 60%. Figures 12A to 12E The optimal PTFE addition level for NW growth was also investigated. It was found that approximately 1 wt% PTFE could achieve an optimal SiC NW yield of 60 wt%. Figure 12F The yield was comparable to that obtained using ferrocene as a catalyst.

[0304] This strategy has been extended to upgrading fly ash (CFA) into SiC NW. Figures 13A to 13B Similar to fire glass, 1 wt% PTFE can also significantly increase the yield of NW from CFA.

[0305] resolution improvement

[0306] For an example of scaled-up NW synthesis, a mixture of Si source (approximately 5.0 g) and metallurgical coke (approximately 5.0 g) was loaded into a quartz tube with an ID of 1.6 cm and an OD of 2.0 cm. Table XIII shows the parameters for an example of scaled-up flash synthesis of SiC nanowires. A large arc welder (TDK Lambda GENESYS 125-80) with a rated power of 10 kW was used as the power source. [Tour '535 application; Eddy 2024]. After 60 s of electrothermal heating, approximately 6 g of SiC NW could be obtained from fireglass and sand / ferrocene. Figures 14A to 14B .

[0307] Table XIII

[0308] Parameters for Scaled-Up Flash Synthesis of SiC Nanowires

[0309]

[0310] Note: The mass ratio of Si source to C is 1:1.

[0311] SiCNW and SiC in polymer composites

[0312] Embodiments of the present invention further include the fabrication of polymer composites comprising SiC nanowires (SiCNW) and SiC. For example, the composites can be prepared as follows: Approximately 3 g of SiCNW was produced to test loading amounts of 0.5 wt%, 1 wt%, 3 wt%, and 5 wt% into a vinyl ester (VE) matrix. 5 g of VE (just received from Fiberglass Supply Depot) was added to a 20 mL scintillation vial, and the amount of SiCNW added to the VE matrix depended on the desired wt% loading amount. The mixture of SiCNW and VE was then stirred at 300 rpm for 30 minutes at room temperature using a magnetic stir bar.

[0313] After stirring, the mixture was then shear-mixed for 3 minutes at approximately 10,000 rpm using a homogenizer. 15 wt% (approximately 0.15 g) of catalyst / hardener methyl ethyl ketone peroxide (MEKP) (Fiberglass Supply Depot) was added to the vial while stirring with a magnetic stir bar at 300 rpm for 5 minutes.

[0314] The composite material for nanoindentation, compression, and thermal conductivity testing was left in the scintillation vial overnight, and the cured composite material was then discharged from the vial. The composite material was then sanded using the side of a grinding wheel, and then with 800, 1000, 1200, 2500, and 3000 grit sandpaper, until it was the appropriate size for microscale mechanical testing. The composite material prepared for tensile testing was poured into a PTFE mold coated with a silicone release agent and allowed to cure overnight.

[0315] Regarding mechanical properties, SiCNW-reinforced vinyl ester (VER) nanocomposites, evaluated using nanoindentation, exhibited an increase in compressive modulus even at 0.5 wt%, resulting in an increase of 26%. Figure 15 The Young's modulus (strip 1501) and hardness (strip 1502) of the VER composite containing SiCNW additives were determined using the indentation method. Compared with pure VER (n = 5), the hardness increased by 84.53% and the Young's modulus increased by 48.6% with a SiCNW filler loading of 3 wt%.

[0316] Macroscale mechanical tests showed improvements in tensile tests at 1 wt% SiCNW composites compared to those at 1 wt%, with increases of 27% and 10% in Young's modulus and ultimate tensile strength (UTS), respectively. Figure 16 (Figures 1601 to 1604 represent filler loadings of 0 wt%, 0.5 wt%, 1 wt%, and 3 wt%, respectively). Figure 17 (Figures 1701 and 1702 represent filler loadings of 0 wt% and 1 wt%, respectively). With the addition of more reinforcing agent, the nanocomposite did not exhibit a linear increase in mechanical properties; however, 0.5 wt% to 3 wt% SiCNW showed some improvement in mechanical properties. Specifically, compared to pure VER, the hardness increased by 84.53% and the Young's modulus increased by 48.6% at a SiCNW filler loading of 3 wt%.

[0317] For the compression of VER containing SiC particles, it was found that the Young's modulus increased by 59.22% and 40.70% in 1 wt% and 5 wt% samples, respectively. Figure 18 (Figures 1801 to 1804 represent filler loadings of 0 wt%, 0.5 wt%, 1 wt%, and 5 wt%, respectively).

[0318] Regarding thermal properties, Figure 19 The diagram shows the temperature of the heat flux relative to the distance of each thermocouple from the sample along the z-axis. The heat flux is calculated from each point using a line fitting that minimizes the least-squares error. Uncertainties in the heat flux and the temperature difference across the sample are calculated using the fitting. With appropriate uncertainty, the sample area is calculated by measuring the sample volume and dividing it by the thickness. All uncertainties are propagated to the final thermal conductivity value.

[0319] Figure 20 Thermal conductivity tests of VER composites containing SiC and SiCNW are shown. (Circles 2001a to 2001d show thermal conductivity at SiC loadings of 0 wt%, 1 wt%, 3 wt%, and 5 wt%, respectively; circles 2002a to 2002d show thermal conductivity at SiCNW loadings of 0 wt%, 1 wt%, 3 wt%, and 5 wt%, respectively). Figure 17 The results show that, at a filler loading of 5 wt%, SiCNW exhibits superior thermal conductivity compared to SiC particles. The nanowires provide a connection path that allows for better conductivity within the composite material.

[0320] Regarding mechanical strength, SiCNWs possess high tensile strength and Young's modulus, which can reinforce the polymer matrix, resulting in stronger and more durable composites. Furthermore, the nanowires can improve the toughness of polymer composites by preventing crack propagation, thereby enhancing resistance to mechanical failure.

[0321] Regarding thermal stability, due to the excellent thermal conductivity of SiCNW and SiC, they can improve the thermal conductivity of polymer composites, which is beneficial for heat dissipation applications. Furthermore, by incorporating SiCNW, the thermal conductivity of the polymer can be increased, which is advantageous for applications requiring heat dissipation. Additionally, in metal matrix composites, SiCNW can reduce the thermal expansion mismatch between the metal matrix and other components, thereby improving thermal stability. These composites are also used in high-temperature applications.

[0322] Regarding weight, the composite material is lightweight. SiCNW has a low density compared to traditional reinforcing materials such as metals. Adding it to polymers can improve the strength-to-weight ratio, which is crucial in aerospace, automotive, and other lightweight applications.

[0323] Regarding corrosion resistance, SiCNW reinforced composites (polymer and metal matrix composites) offer better corrosion resistance, especially in harsh environments, which can extend the service life of the composites and improve their durability.

[0324] Regarding abrasion resistance, SiCNW can improve the abrasion and wear resistance of polymer composites and metal matrix composites, which is extremely important in applications involving friction, wear, ablation, or corrosion, such as gears, moving parts, wind turbine blades, aircraft, rockets, helicopter blades, turbine blades, missiles, or spacecraft. Similarly, the abrasion resistance, wear resistance, corrosion resistance, or ablation resistance of SiCNW makes it suitable for use as a protective coating for wind turbine blades, aircraft, rockets, helicopter blades, turbine blades, missiles, or spacecraft.

[0325] Si nanowires

[0326] In some of the flashes performed, the flash time was modulated during nanowire synthesis. XRD patterns revealed the coexistence of Si and SiC after flashing. It was found that increasing the number of flashes from one to five resulted in an increase in Si content from approximately 0.2 wt% to approximately 37 wt%, accompanied by an iron signal. However, even for the product after five flashes, both SiC and Si signals were observed in Raman and XPS spectra.

[0327] Possible reaction pathways were analyzed using the Gibbs free energy changes calculated at each step. These results indicate that Fe cannot directly reduce the SiO2 precursor to Si, but it will react with carbothermally reduced SiC and catalyze the formation of Si nanowires. Furthermore, other metals favorable for Si nanowire formation can be used instead of iron.

[0328] Since iron residues (or other residues depending on the process used) can be removed (e.g., by washing), Si NW can be used in applications such as Si NW suitable for use in batteries.

[0329] B4C nanowires

[0330] Embodiments of the present invention further include the synthesis of B4C nanowires (B4C NW) via flash Joule heating. For example, B4C NW can be grown via flash Joule heating as follows. The B source includes boron powder (Millipore-Sigma, 95%) and boric acid (Millipore-Sigma, 99.5%), wherein the carbon source is carbon black or metallurgical coke. The catalyst is a metal salt and primarily includes at least one of the following metal elements: Fe, Co, and Ni. Other metals, such as Mo, Cr, V, Ru, Rh, and Nb, may also catalyze nanowire growth. Ferric chloride (FeCl3), ferrocene, iron(III) acetylacetonate (Fe(acac)3), nickel(II) acetylacetonate (Ni(acac)2), and cobalt(II) acetylacetonate (Co(acac)2) are used as catalysts for the synthesis of B4C NW.

[0331] For catalyst loading, a solvent is typically used to uniformly load the catalytic metal ions onto the precursor surface. Experimentally, 5 mg to 50 mg of metal salt is dissolved in 10 mL of ethanol, resulting in a concentration of 0.01 g / mL. -1 Up to 0.05 g mL -1 Next, a mixture of 1 g of B and C sources was added to the ethanol solution and immersed in an ultrasonic bath (Cole-Parmer ultrasonic cleaner) for 15 minutes. The mixture was then dried overnight in a vacuum dryer to ensure uniform loading of the metal catalyst. Thus, the catalyst loading could be calculated to be 0.5 wt% to 5 wt%. For large-scale catalyst loading, 0.25 g to 2.5 g of catalyst was also mixed with 50 g of B and C sources for 3 hours at 400 rpm using a planetary ball mill (MSESupplies, PMV1-0.4L).

[0332] During the nanowire synthesis process, 300 mg of dried precursor loaded with catalyst was loaded into a quartz tube with an inner diameter (ID) of 8 mm and an outer diameter (OD) of 12 mm, and two graphite electrodes (on each side). The tube was loaded onto a fixture and connected to an external flash power system. A commercial arc welder was used as the power source, with the input voltage set to 120 V. For larger scales, 3 g of precursor was placed in a quartz tube with an inner diameter (ID) of 12 mm and an outer diameter (OD) of 16 mm. Table XIV shows the parameters used for the flash synthesis of B4C nanowires.

[0333] Table XIV

[0334] Parameters used for the flash synthesis of B4C nanowires

[0335]

[0336] Note: BA represents boric acid. B represents boron powder. CB represents carbon black. For each batch of 300 mg sample, use an 8 mm inner diameter (ID) tube as the reactor. For each batch of 3 g sample, use a 16 mm inner diameter (ID) tube as the reactor.

[0337] The relationship between electrothermal heating time and B4C NW yield was investigated. Generally, a longer heating time resulted in a higher B4C NW yield. Figure 21 Considering that NW did not increase significantly after 60 seconds, a heating time of 60 seconds was chosen for the example.

[0338] In the examples, different catalysts were used (including ferrocene, FeCl3, Fe(NO3)3, Fe(acac)3, Co(acac)2, and Ni(acac)2). These catalysts can be used for B4C NW synthesis. However, Fe-based catalysts often yield better NW yields. Figure 22 .(exist Figure 22 In this study, the loading of all catalysts was set to 1.0 wt% and the heating duration was 60 s.

[0339] The catalyst loading was adjusted from 0.1 wt% to 2.5 wt%. Figures 23A to 23D It was found that increasing the catalyst content increased the yield and diameter of the nanowires. However, when the catalyst content increased to above 1.0 wt%, the yield did not show a significant increase. Figures 24A to 24D ; Figure 25 .

[0340] The newly synthesized NW was characterized. XRD patterns and Raman spectra showed that the newly synthesized NW was B4C. Figures 26A to 26B The slight oxidation peaks in the B 1s XPS spectrum originate from oxidation on its surface. Figure 26C .

[0341] Boron powder is also used as a boron source. Figures 27A to 27C It is also a promising precursor for the synthesis of B4C NW.

[0342] Therefore, the process of embodiments of the present invention is faster, more energy-efficient, and cheaper than other methods in producing gram-scale transition metal dichalcogenides. The crystallinity of the product is comparable to that produced via chemical vapor deposition (which requires several minutes to several hours).

[0343] These processes are also kinetically driven, rather than thermodynamically driven, allowing the formation of products that cannot be synthesized by many other methods. Compared to conventional flash Joule heating, this method allows the formation of products that would normally not be formed.

[0344] While embodiments of the invention have been shown and described, modifications can be made thereto by those skilled in the art without departing from the spirit and teachings of the invention. The embodiments and examples provided herein are merely illustrative and not intended to be limiting. Many variations and modifications of the invention disclosed herein are possible and are within the scope of the invention. The scope of protection is not limited by the foregoing description, but only by the following claims, which include all equivalents of the subject matter of the claims.

[0345] All patents, patent applications and publications cited in this document are hereby incorporated in their entirety by reference to the extent that they provide illustrative, procedural or other details for the purposes set forth herein.

[0346] Quantities and other numerical data may be presented in range format throughout this document. It should be understood that this range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the numerical values ​​explicitly stated as the limits of the range, but also all individual numerical values ​​or subranges encompassing that range, as if each numerical value and subrange were explicitly stated. For example, a numerical range of approximately 1 to approximately 4.5 should be interpreted not only to include the explicitly listed limits of 1 to approximately 4.5, but also to include individual numerical values ​​such as 2, 3, and 4, and subranges such as 1 to 3, 2 to 4, etc. The same principle applies to ranges listing only a single numerical value, such as “less than approximately 4.5,” which should be interpreted to include all the aforementioned values ​​and ranges. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0347] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the subject matter of this disclosure pertains. Although any methods, apparatus, and materials similar or equivalent to those described herein may be used in the practice or testing of the subject matter of this disclosure, representative methods, apparatus, and materials are described here.

[0348] According to long-standing patent law practice, the terms “a” and “an” are used in this application (including the claims) to mean “one or more”.

[0349] Unless otherwise specified, all figures used in this specification and claims to indicate quantities of ingredients, reaction conditions, etc., should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise indicated, the numerical parameters set forth in this specification and appended claims are approximations that may vary depending on the desired properties sought to be obtained according to the subject matter disclosed herein.

[0350] As used herein, when referring to values ​​or amounts of mass, weight, time, volume, concentration, or percentage, the terms “about” and “substantially” are intended to cover variations of ±20% of a specific amount in some embodiments, ±10% of a specific amount in some embodiments, ±5% of a specific amount in some embodiments, ±1% of a specific amount in some embodiments, ±0.5% of a specific amount in some embodiments, and ±0.1% of a specific amount in some embodiments, as such variations are suitable for carrying out the disclosed methods.

[0351] As used herein, the terms “substantially perpendicular” and “substantially parallel” are intended to cover the following variations: in some embodiments, within ±10° in the vertical and parallel directions, respectively; in some embodiments, within ±5° in the vertical and parallel directions, respectively; in some embodiments, within ±1° in the vertical and parallel directions, respectively; and in some embodiments, within ±0.5° in the vertical and parallel directions, respectively.

[0352] As used herein, the term “and / or” in the context of a list of entities means that the entities exist individually or in combination. Thus, for example, the phrase “A, B, C and / or D” includes not only A, B, C, and D individually, but also any and all combinations and sub-combinations of A, B, C, and D.

[0353] References

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Claims

1. A method for synthesizing a material, wherein the method comprises: (a) Forming a mixture containing one or more element sources and a catalyst; as well as (b) Using the mixture, a flash Joule heating process is performed to form a structure selected from the group consisting of fibers, fibrils, whiskers, nanotubes, and one-dimensional structures, wherein... (i) The flash Joule heating process includes applying a voltage across the mixture for one or more flash time periods, and (ii) The product comprises a material selected from the group consisting of carbides, borides, nitrides, boron nitrides, boron carbides, BNC, oxynitrides, carbon nitrides, oxides, dioxides, sulfides, disulfides, selenides, diselenides, tellurides, ditellurides, phosphides, oxycarbides, oxyborides, oxynitride carbides, oxyboron nitrides, oxyboron carbides, OBNC, arsenides, and antimony compounds.

2. According to the method described in 1, wherein (a) The structure comprises an inorganic compound. (b) The inorganic compound comprises a first element or compound selected from the group consisting of boron, silicon, carbon, aluminum, germanium, tin, gallium, indium, lead, copper, zinc, cadmium, magnesium, titanium, cobalt, tungsten, vanadium, hafnium, niobium, molybdenum, zirconium, tantalum, and combinations thereof, and (c) The inorganic compound contains a second element or compound selected from the group consisting of C, B, O, N, S, P, As, Sb, Se, Te, Si, Ge, Sn, I and combinations thereof.

3. The method according to any one of claims 1 to 2, wherein the inorganic compound is selected from the group consisting of transition metal dichalcogenides, mixed chalcogenide transition metal dichalcogenides, transition metal dichalcogenides containing more than one type of transition metal, III-V compounds, II-VI compounds, I-VII compounds, group IV compounds, group IV elements, IV-VI compounds, and mixtures thereof.

4. The method according to any one of claims 1 to 3, wherein the catalyst is an element comprising a group metal, a transition metal, a lanthanide, or an actinide, a salt, a polyoxometalate, or an organometallic compound.

5. The method according to any one of claims 1 to 4, wherein the mixture further comprises a growth promoter or regulator containing an element selected from the group consisting of F, S, Se, Cl, Br, I, P, O or N, which is added to the mixture to enhance the growth of the one-dimensional structure.

6. A method for synthesizing silicon carbide fibers or fibrils, wherein the method comprises: (a) Forming a mixture containing a silicon source, a carbon source and a catalyst; as well as (b) Using the mixture to perform a flash Joule heating process to form silicon carbide fibers or fibrils, wherein the flash Joule heating process includes applying a voltage across the mixture for one or more flash time periods.

7. The method according to claim 6, wherein the silicon source or carbon source is selected from the group consisting of powder, fiber, silicone, sodium silicate, iron silicate, silicate, aluminosilicate, silicon oxide, silicon dioxide, fiber-reinforced plastic particles, silicon wafers and waste solar panels.

8. The method of claim 6, wherein the silicon source or carbon source comprises fiber-reinforced plastic particles derived from the group consisting of fiber-reinforced plastics, reinforced metal laminates, and combinations thereof.

9. The method according to any one of claims 6, wherein the silicon source or carbon source comprises fibers selected from the group consisting of waste fibers, glass fibers, carbon fiber plastics, quartz fibers, basalt fibers, rock wool, polymer fibers, plant fibers, asbestos, rock fibers, mineral fibers, and combinations thereof.

10. A method for synthesizing B4C nanowires, wherein the method comprises: (a) Forming a mixture containing a boron source, a carbon source and a catalyst; as well as (b) Using the mixture to perform a flash Joule heating process to form the B4C nanowires, wherein the flash Joule heating process includes applying a voltage across the mixture for one or more flash time periods.

11. The method according to claim 15, wherein the boron source is selected from the group consisting of boric acid, boron oxide, borax, metal borates, boranes, carboranes, and combinations thereof.

12. The method according to any one of claims 10 to 11, wherein the carbon source is selected from the group consisting of carbon black, coke, silicone, carborane, graphite, graphene, carbon fiber, carbon nanotubes, biochar, and combinations thereof.

13. The method according to any one of claims 10 to 12, wherein the catalyst comprises a metal catalyst selected from the group consisting of metal salts, metal powders, polyoxometalates, organometallic compounds, and combinations thereof.

14. A method for synthesizing silicon carbide fibers or fibrils, wherein the method comprises: (a) Forming a mixture comprising fiber or fiber-reinforced plastic particles and a catalyst; as well as (b) Using the mixture to perform a flash Joule heating process to form silicon carbide fibers or fibrils, wherein the flash Joule heating process includes applying a voltage across the mixture for one or more flash time periods.

15. An apparatus comprising: (a) A container operable to receive a mixture comprising fiber-reinforced plastic particles and a metal catalyst; as well as (b) An electrode operable to apply a voltage pulse across the mixture for one or more flash time periods to subject the mixture to a flash Joule heating process, wherein the flash Joule heating process on the mixture results in the mixture being converted into silicon carbide fibers or fibrils.

16. The apparatus of claim 15, wherein the apparatus is further operable to perform the method of claim 14.

17. A method for manufacturing a polymer composite material, wherein the method comprises: (a) Forming a mixture comprising fiber-reinforced plastic particles; (b) Using the mixture, a flash Joule heating process is performed to form silicon carbide material, wherein (i) The flash Joule heating process includes applying a voltage across the mixture for one or more flash time periods, and (ii) The silicon carbide material is selected from the group consisting of silicon carbide particles, silicon carbide fibers and silicon carbide protofibrils; (b) Loading 0.5 wt% to 5 wt% of the silicon carbide material into a liquid polymer matrix; as well as (c) Curing the liquid polymer matrix to form the polymer composite material.

18. The method of claim 17, wherein the silicon carbide material is SiC and the polymer composite material is a SiC-polymer composite material.

19. The method of claim 17, wherein the silicon carbide material is silicon carbide fiber or fibril and the polymer composite material is SiC fiber or fibril-polymer composite material.

20. The method of claim 17, wherein the silicon carbide material is silicon carbide nanowires and the polymer composite material is a SiC nanowire-polymer composite material.

21. A method for synthesizing silicon carbide particles, wherein the method comprises: (a) Forming a mixture comprising fiber-reinforced plastic particles; as well as (b) Using the mixture to perform a flash Joule heating process to form silicon carbide particles, wherein the flash Joule heating process includes applying a voltage across the mixture for one or more flash time periods.

22. The method of claim 21, wherein the step of forming the mixture comprises forming the fiber-reinforced plastic particles from a material selected from the group consisting of fiber-reinforced plastics, reinforced metal laminates, and combinations thereof.

23. The method according to any one of claims 21 to 22, wherein applying the voltage across the mixture is controlled by controlling the modulated input pulse voltage and by controlling the duration of the one or more flashing time periods.

24. The method of claim 23, wherein controlling the application of the voltage across the mixture controls the phase purity of the silicon carbide particles produced by the flash Joule heating process.

25. An apparatus comprising: (a) A container operable to receive a mixture comprising fiber-reinforced plastic pellets; as well as (b) An electrode operable to apply a voltage pulse across the mixture for one or more flash time periods to subject the mixture to a flash Joule heating process, wherein the flash Joule heating process on the mixture causes the fiber-reinforced plastic particles to be converted into silicon carbide particles.

26. The apparatus of claim 25, wherein the apparatus is further operable to perform the method of any one of claims 21 to 24.

27. A method comprising: (a) Silicon carbide particles are produced from fiber-reinforced plastics using the method according to any one of claims 21 to 24; (b) Using the silicon carbide particles as the negative electrode material of the battery.

28. A battery manufactured by the process according to claim 27.

29. A battery comprising an electrode containing silicon carbide particles, said silicon carbide particles being produced from fiber-reinforced plastic using the method according to any one of claims 21 to 24.

30. A method comprising: (a) Silicon carbide particles are produced from fiber-reinforced plastics using the method according to any one of claims 21 to 24; (b) Using the silicon carbide particles for applications selected from the group consisting of composite material reinforcement, semiconductor, photocatalysis and electrocatalysis.

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