Niobium superconducting radio frequency cavities (SRF) are required for the International Linear Collider as well as other high energy physics projects. In order for these cavities to achieve the required particle acceleration gradients, electropolishing is conducted as a final surface finishing operation. Conventional electropolishing of SRF cavities is based on the well-established viscous salt film paradigm [[1]] and utilizes a viscous electrolyte consisting of a mixture of sulfuric acid (95-98%) and hydrofluoric acid (49%) in a 9:1 volume ratio [[2]]. The concentrated is included to establish a thick, viscous boundary layer to result in surface brightening or smoothing [[3]]. The hydrofluoric acid is included to remove the niobium oxide film formed during electropolishing [[4]]. Previously we described efforts directed towards demonstrating an innovative electropolishing process for niobium coupons in low concentration (5%) aqueous sulfuric acid without hydrofluoric acid enabled by pulse reverse voltage waveforms electrolyte [[5],[6]]. The advantages of pulse reverse voltage electropolishing are summarized in in Figure 1. Specifically, the forward (anodic) pulse on-time and peak voltage are tuned to eliminate the need for concentrated sulfuric acid; the off-time is adjusted to dissipate heat, and the reverse (cathodic) pulse on-time and peak voltage are tuned to eliminate the need for hydrofluoric acid. In this contribution, we review and describe continuing efforts leading to the scale-up of the electropolishing process to single-cell and three-cell niobium SRF cavities [[7],[8]]. Finally, we present a first order economic comparison of the pulse reverse voltage low concentration aqueous sulfuric acid process compared to baseline concentrated sulfuric acid-hydrofluoric acid process [[9]]. Acknowledgements: The financial support of Faraday corporate, DOE P.O. No. 594128 and DOE Contract No. DE-SC0004588 is acknowledged. [1] Jacquet, P.A. (1936) On the Anodic Behavior of Copper in Aqueous Solutions of Orthophosphoric Acid. Trans. Electrochem. Soc. 69 (1) 629-655. [2] Tian, H., Corcoran, S., Reece, C. and Kelly, M. (2008) The Mechanism of Electropolishing of Niobium in Hydrofluoric-Sulfuric Acid Electrolyte. J. Electrochem. Soc., 155 , D563-568. [3] D. Landolt , (1987) “Fundamental Aspects of Electropolishing” Electrochimica Acta 32(1) 1-11 (1987). [4] MacDougall, B. (1995) “The Importance of Surface Oxide Films in Corrosion, Semiconductor and Environmental Research” Proceedings of the Symposium on High Rate Metal Dissolution Processes, Vol. 95-19, (Eds. M. Datta, B. MacDougall and J. Fenton) The Electrochemical Society, Pennington, NJ, pp 16-31. [5] M. Inman, E.J. Taylor, T.D. Hall “Electropolishing of Passive Materials in HF-Free Low Viscosity Aqueous Electrolytes” J. Electrochem. Soc., 160 (9) E94-E98 (2013). [6] E.J. Taylor, M.E. Inman, T.D. Hall (2015) “Electrochemical system and method for electropolishing superconductive radio frequency cavities” U.S. Patent No. 9,006,147 issued April 14, 2015. [7] E.J. Taylor, T.D. Hall, M. Inman, S. Snyder (2013) “Electropolishing of Niobium SRF Cavities in Low Viscosity Aqueous Electrolytes without Hydroflouric Acid” Paper No. TUP054, Presented SRF2013, Paris, FRANCE. [8] A.M. Rowe, A. Grassellino, T.D. Hall, M.E. Inman, S.T. Snyder, E.J. Taylor (2013) “Bipolar EP: Electropolishing without Flourine in a Water Based Electrolyte” Paper No. TUIOC02, Presented SRF2013, Paris, FRANCE. [9] E.J. Taylor, M. Inman, T. Hall, S. Snyder, A. Rowe, D. Holmes (2015) “Economics of Electropolishing Niobium SRF Cavities in Eco-Friendly Aqueous Electrolytes without Hydrofluoric Acid” Paper No. MOPB092, Presented SRF2015, Whistler, CANADA. Figure 1

The development of next generation materials and manufacturing technologies is critical for increasing industrial competitiveness, improving economic strength, and driving economy-wide decarbonization. Thermal and/or electrical conductivity-enhanced materials have been demonstrated as promising elements for the decarbonized industry sector with a wide variety of applications. High thermal conductivity materials enable new capabilities for the applications on sensors, detectors, and accelerators. The sluggish conduction cooling rate of conventional materials, such as copper, aluminum, or graphite, hinders the application of the cryogenic cooling systems. Graphene are two-dimensional nanocarbon materials with excellent physical and chemical properties, such as thermal and electronic conductivity, high mechanical strength, large specific surface area. The intrinsic physiochemical properties of graphene and a metal (copper) matrix, combined with advanced fabrication techniques, could tailor graphene-copper hybrid properties and make the hybrid as ideal thermal strap materials for conduction cooling systems. In this work, Faraday Technology Inc. and Utah State University will discuss an efficient, scalable, manufacturing-ready approach to produce high conductive graphene-copper hybrid foils/coatings and demonstrate their applications in thermal straps for conduction cooling, as well as in electronic devices as low resistance electrical pathways. The innovative electro-codeposition manufacturing process is based on the use of pulsed electric fields, for controlled, reproducible, scalable deposition of Cu and graphene materials simultaneously to form incorporated graphene-Cu hybrid foils. The graphene composition in the hybrid foils was confirmed by Raman spectrometry. The thermal conductivity of fabricated Cu-Graphene foil was ~50% higher than that of commercial Cu foil. Currently. we are scaling up the fabrication process for large scale production of graphene-copper hybrid foils for the thermal strap application. In summary, a scalable manufacturing process for synthesizing high conductive graphene-copper hybrids has been demonstrated. The work will be continued on thermal straps fabrication and performance evaluation, as well as other applications demonstration, such as low resistance backplanes for electronic devices. Acknowledgements: The financial support of DOE SBIR program through grant No. DE-SC0021676 (Phase I&II) is acknowledged.

The development of next generation materials with enhanced thermal and/or electrical conductivity will be beneficial for both terrestrial and space applications, ranging from thermal links for conduction cooling of cryogenic instruments and optical systems, mirror substrates for space telescopes, coolant tubes for heat exchangers and deployable radiators, space landing systems, to high powered electronics and beyond. The cryogenic cooling systems are essential for the advancement of terrestrial and space's science goals, which enable new capabilities on sensors, detectors, and accelerators, such as for near- and mid-IR instruments on SmallSats and CubeSats for Earth and Lunar observations, for cooling of far- and mid-IR optics, and for extracting heat dissipation of superconducting radio frequency cavity. High conductive thermal straps play a critical role in balancing heat dissipation and reaching the operating temperature of the instruments. The sluggish conduction cooling rate of conventional thermal straps made from copper, aluminum, or graphite hinders the application of thermal straps on the cryogenic cooling systems. Within this context, we will discuss an efficient, scalable, manufacturing-ready approach to produce high conductive graphene-copper hybrid foils and demonstrate their application in thermal straps for the conduction cooling of cryogenic instruments and optical systems. This technology utilizes the intrinsic physiochemical, thermal, and mechanical properties of graphene and copper matrix, combined with advanced electrodeposition techniques for hybrid material fabrication. An innovative manufacturing process based on the use of pulsed electric fields and the combination of electrodeposition and electrophoretic deposition (EPD), have been developed for controlled, reproducible, scalable production of graphene-copper hybrid foils/coatings. The hybrid exhibited enhanced conductivity and mechanical strain for fast conduction cooling processes. Next step, we will work on the thermal strap fabrication using synthesized graphene-copper hybrid foils and their performance evaluation. Acknowledgements: The financial support of DOE SBIR program through grant No. DE-SC0021676 (Phase I&II) is acknowledged.

Faraday will describe our recent work on the development of a one-step electrochemical surface preparation process to prepare aluminum alloys for direct electrodeposition. Coating on aluminum commonly requires extensive surface pretreatment processes prior to deposition, owing to aluminum’s reactive nature and affinity for oxygen, leading to the formation of an oxide film that negatively affects coating adhesion to the substrate. Therefore, preparing the surface is critical to remove any oils or dirt attached to the surface and to remove the native oxide film to increase coating adhesion. Conventionally these issues are addressed by a continuous sequence of twelve (12) pretreatment process steps to prepare the surface for deposition. Such an extensive number of processing steps requires significant capital investment for a new vendor, increases the probability of errors during the process, is time consuming (lower industrial throughput that ties up equipment), and requires large volumes of hazardous chemicals (Hydrofluoric Acid) that are environmentally unfavorable and introduce cost and safety concerns. Therefore, alternative techniques that do not require such extensive pretreatment processing with similar or better performance to conventional methods are desired. Faraday has recently developed a simple environmentally benign pretreatment process utilizing our pulse reverse electrofinishing approach that can dramatically reduce the number of procedures and complexities required to prepare the surface for the direct deposition onto Al alloys. A specific application of interest that requires low-cost, simple fabrication technology for the deposition of wear, erosion, corrosion fatigue resistant coatings onto Al is Neutrino Focusing Horns. Neutrino Focusing Horns, required for research on particle accelerators and storage rings, are commonly made of aluminum. These horns must withstand repetitive thermal and magnetic loadings over millions of pulses in a radiation and corrosive environment and the thickness of the inner conductor is minimized to reduce absorption and scattering of secondary particles in the conductor material. Therefore, protection of the focusing horns from erosion, corrosion and fatigue is of critical importance to assure long time reliability. The most successful coating thus far has been an electroless nickel coating with conventional 12 step pretreatment method. The application of this coating, however, is challenging due to the large size of the horn (4 m x 1 m x 1 m), and industrialization is challenging due to the low part volumes, high capitalization and large number of process steps. This presentation will focus pulse/pulse reverse surface preparation processes being developed by Faraday Technology. It will explore surface pretreatment procedures to simultaneously prepare various Al surfaces such as Al 6061, Al 4043, Al 1100, and Al 5086 and subsequent direct deposition of ZnNi, NiP, or Ni coatings. These coating have since been characterized and compared to baseline electroless NiP coatings for their functional properties. The results of these characterization studies will be discussed in detail.

Faraday Technology Inc. is a research, development and electrochemical engineering firm developing electrochemical innovations based has pulse/pulse reverse electrolytic principles. [1,2] With that founding basis Faraday has been able to bridge the gap between academic understanding and small-scale demonstrations to commercialization of practical components for over 32 years of operation. This presentation will discuss a broad range of electrodeposition studies including single metal, alloy, composite and electrophoretic. We will highlight some of the key factors that determine the usefulness and successfulness of using pulse/pulse reverse principles to apply materials to a broad range of structures. For instances, we will discuss additive free Cu deposition into a microvia, functionally graded NiMo coatings from a single electrolyte, graphene incorporation into a Cu film, and electrophoretic deposition of CNTs. Each process utilized pulse/pulse reverse plating to overcome key challenges with diffusion, stress, composition, adhesion, and functional properties. References: J. Taylor “Adventures in Pulse/Pulse Reverse Electrolytic Processes: Explorations and Applications in Surface Finishing” J. Applied Surface Finishing, 3(4), 178-189 (2008). J. Taylor, et al., (2019; Chapter 7) “Breaking the Chemical Paradigm in Electrochemical Engineering: Case Studies and Lessons Learned from Plating to Polishing” R.C. Alkire (Volume 18). Electrochemical Engineering: The Path from Discovery to Product.Wiley-VCH.

Cellulose is the most abundant biomass material in nature utilized for the manufacturing of cellulosic nanomaterials that exhibit great potential in a variety of industrial applications. Although cellulosic nanomaterial is cost-effective to produce, it is not economical to ship long distances while containing significant water content (>95 wt.%). Therefore, a need has been identified by manufacturers to develop energy-efficient, dewatering or drying of cellulosic nanomaterials. Accordingly, Faraday Technology in collaboration with GranBio USA, manufacturers of cellulosic nanomaterials, is addressing this need by developing electrochemical based dewatering system and process to dewater cellulosic nanomaterials while maintaining material properties when dried and re-dispersed. Energy-efficient (70% reduction in energy requirements compared to thermal dewatering), environmentally beneficial (51% reduction in greenhouse gas emissions), economical (31% reduction in cost/ton of dried material), and industrially viable electrochemical based dewatering approach to process up to 2 tons/year of dried nanocellulose at alpha-scale has been demonstrated. The approach is capable of achieving >50 wt.% final solids and 18 wt.% final solids, that could be rehydrated under vortex and confirmed for re-dispersibility. Material properties (structure, particle size) were maintained by the dewatered cellulosic nanomaterials. Specifically, this talk will discuss the results of these advancements. Acknowledgements: The financial support of DOE Contract No. DE-SC0018787 is acknowledged.

Among the numerous technological advances sought in order to facilitate human exploration and habitation outside of earth’s atmosphere, solutions and innovations are needed for processing resources locally to support sustainable and long duration space missions. Such in-situ resource utilization (ISRU) is aimed at reducing the payload mass during launch and eliminate the need for ground support for long-term missions and ultimately space colonization. Disinfection needs is an area of particular need, which is currently accomplished through the use of pre-packaged, disposable, wetted disinfection wipes. These items represent an appreciable carry-along mass and disposal/replacement burden requiring ground support. Therefore, a system is desired that could utilize onboard utilities to create disinfecting solutions to eliminate storage/disposable problems of the wetted wipes and further reduce the astronaut’s dependence on earth-based supplies. Faraday Technology Inc. is addressing this challenge by demonstrating an in-situ approach, which utilizes on-board supplies of air and water for on demand electrochemical generation of hydrogen peroxide. Hydrogen peroxide is well-established disinfectant with non-toxic decomposition products (viz., O 2 and H 2 O), that is safe enough for human contact to be sold commercially as a 1-5 w/w% solution, which makes it an ideal disinfecting solution for closed space environments. Faraday has continued to improve the TRL by scaling the electrochemical peroxide generation system from a sub-scale to alpha-scale process in order to deliver 1 L per day of ~2 w/w% hydrogen peroxide for disinfectant applications from DI water feed-stream with air as a feed source [1],[2],[3],[4] . These electrolytes were then sent to NASA for microbial control property characterization. This system eliminates the need to ferry disinfectant wipes to manned space capsules and is a critical enabling technology for future moon-based missions and beyond. Specifically, this talk will discuss the results of these advancements. Acknowledgements: Financial support of NASA Contracts NNX16CA43P, NNX17CJ12C, 80NSSC20C0070, and 80NSSC23CA036 is acknowledged. References: [1] Vijapur, Santosh H., et al. "Electrochemical peroxide generation." ECS Transactions 77.11 (2017): 947. [2] Vijapur, Santosh, et al. "In-Situ Resource Utilization for Electrochemical Generation of Hydrogen Peroxide for Disinfection." 49th International Conference on Environmental Systems, 2019. [3] Nelson, George J., et al. "Electrochemistry for Space Life Support." The Electrochemical Society Interface 29.1 (2020): 47. [4] Vijapur, Santosh, et al. "In-Situ Resource Utilization for Electrochemical Generation of Hydrogen Peroxide for Disinfection." 50th International Conference on Environmental Systems, 2021.

Faraday Technology Inc. is a research, development and electrochemical engineering firm developing electrochemical innovations based has pulse/pulse reverse electrolytic principles. [1,2] With that founding basis Faraday has been able to bridge the gap between academic understanding and small-scale demonstrations to commercialization of practical components for over 32 years of operation. This presentation will discuss a broad range of surface finishing studies including a wide range of metals, additively manufactured parts, electrochemical machining, and highly complex structures. We will highlight some of the key factors that determine the usefulness and successfulness of using pulse/pulse reverse principles to enable simple water-based HF free electrolytes to finish or shape a wide range of metal surfaces. For instances, we will discuss electropolishing of Nb superconducting cavities, additively manufactured grade 5 Ti impellers, and electrochemical machining to create complex impossible to machine shapes. Each process utilizes pulse/pulse reverse operations to overcome key challenges with boundary layer control, oxidation/reduction of the surface, and the uniformity of the finish. References: J. Taylor “Adventures in Pulse/Pulse Reverse Electrolytic Processes: Explorations and Applications in Surface Finishing” J. Applied Surface Finishing, 3(4), 178-189 (2008). J. Taylor, et al., (2019; Chapter 7) “Breaking the Chemical Paradigm in Electrochemical Engineering: Case Studies and Lessons Learned from Plating to Polishing” R.C. Alkire (Volume 18). Electrochemical Engineering: The Path from Discovery to Product.Wiley-VCH.

Radiant energy conversion and storage eliminate the mass transfer process induced power output limitation, and open a new vista for energy utilization. An effective system for harvesting radiant energy from both solar and thermal radiation will be beneficial for further radiant energy utilization. On the other hand, space observatory missions require low-reflectivity surfaces/coatings for space-borne instruments, such as seeker telescopes, optical sensors, etc., to minimize stray and reflected light on targeted telescope and baffle materials and construction. The excellent optical, thermal, and mechanical properties of carbon nanotubes (CNTs) make them as ideal coating materials for absorbing the broadband spectrum across UV-Vis-IR regions. In this presentation, Faraday Technology will discuss an innovative electrophoretic deposition (EPD) manufacturing process, based on the use of pulsed electric fields, for controlled, reproducible, scalable deposition of a wide variety of carbon nanotube based coatings across a broad range of substrates, geometries and sizes (Figure 1 a). The effects of waveforms, electrolytes, substrates, etc. on the formation of robust and uniform coating will be discussed in this talk. The optical properties, and environmental survivability of carbon nanotube coatings will be demonstrated via a variety of testing or characterizations. The CNT coatings show the total hemispherical reflection of 0.5% - 1% across UV-Vis to near infrared (NIR) wavebands, which is much lower than the reflectance of the typically used Z306 black paint (Figure 1 b). These CNT coatings also withstood simulated launch conditions vibrational tests, and demonstrated no weight loss and optical degradation. Furthermore, the CNT coatings were evaluated for atomic oxygen erosion resistance in a simulated low earth orbit (LEO) environment, and showed enhanced resilience when compared to Kapton and HOPG. Faraday will also introduce their applications in low-reflective coatings and solar thermal absorbers for radiant energy harvesting and conversion. In summary, a scalable EPD manufacturing process for fabricating carbon nanotube based coatings have been developed at Faraday for the applications in the field of low-reflective coatings and broadband solar thermal absorbers. Acknowledgements: The financial support from NASA SBIR program through contracts No. 80NNSC18P2062 & 80NSSC19C0177, DARPA SBIR program through grant No. W31P4Q-22-C-0014, DOD MDA STTR program through grant No. HQ0147-19-C-7065, and DOD Air Force SBIR program through grant No. FA9550-22-P-0015 are acknowledged. Figure 1

National Space Weather Strategy and Action plan calls for the need to enhanceProtection of National Security, Homeland Security, and Commercial Assets and Operations against Effects of Space Weather. Extreme space weather event like solar flares, cosmic rays, and radiation belts cause ionizing radiation that can damage electronics, solar arrays, and optical systems on satellites reducing their functionality and lifetimes, by inducing an ionic charge on the spacecraft’s surface, when a spacecraft fly in and out of the ionosphere. This negative charge buildup can lead to ion sputtering/arcing, and producing irreparable damage in spacecraft components. Therefore, the local application of materials systems that can passively mitigate the negative charge build up by emitting the electron back into space, while improving resistance to erosion during ion sputtering is of interest. Accordingly, Faraday Technology is developing a low-cost, efficient and scalable manufacturing process for the local deposition of lightweight passive highly emissive and erosion resistant coating onto spacecraft viable substrates that can mitigate charging and erosion effects from ionizing radiation. The composite coating showed a ~1500% increase in maximum (Emax) total electron yield over bare aluminum, extending by 4 times the range of electron yields between crossover energies >1, and demonstrated the potential for erosion resilience in modeled International Space Station plasma erosion conditions. The composite coating could be applied to various spacecraft platforms include spacecraft skin, solar arrays, circuit boards, and emitters such that their lifetime, effectiveness and durability within LEO/GEO environments events can be enhanced. Acknowledgements:The financial support of NASA SBIR/STTR program through contract No.80NSSC22PB020 is acknowledged.

Faraday Technology Inc. is a research, development and electrochemical engineering firm developing electrochemical innovations based has pulse/pulse reverse electrolytic principles. [1,2] With that founding basis Faraday has been able to bridge the gap between academic understanding and small-scale demonstrations to commercialization of practical components for over 32 years of operation. This presentation will discuss techniques where pulse/pulse reverse operation enabled improved production rates, reduced energy demand, eliminated biofouling, and enabled recycling of complex structures. We will highlight some of the key factors that determine the usefulness and successfulness of using pulse/pulse reverse principles to improve process control of the electrochemical operations. For instances, we will discuss electrochemical destruction of PFAS, electrocatalytic operations, and carbon fiber recovery from composites. References: J. Taylor “Adventures in Pulse/Pulse Reverse Electrolytic Processes: Explorations and Applications in Surface Finishing” J. Applied Surface Finishing, 3 (4), 178-189 (2008). J. Taylor, et al., (2019; Chapter 7) “Breaking the Chemical Paradigm in Electrochemical Engineering: Case Studies and Lessons Learned from Plating to Polishing” R.C. Alkire (Volume 18). Electrochemical Engineering: The Path from Discovery to Product . Wiley-VCH.

Deferred-action batteries, also known as reserve batteries, fulfill a unique role among energy storage technologies in which long-term shelf life (years, decades) is required while ensuring optimal performance upon activation. This objective is typically achieved through isolation of the electroactive components until battery operation is desired. Commonly, the electrolyte is isolated from one or both electrodes, and thus, limiting premature degradation and parasitic side-reactions until battery power is needed. During the reserve battery activation process, electrolyte is delivered to the electrode(s), which enable ionic conduction between the anode and cathode, and thus permitting normal operations analogous to a non-reserve design – which is ubiquitous among off-the-shelf batteries. The feasible activation mechanisms are largely determined by battery chemistries and material properties, which give rise to several classifications including: thermal, spin-activated, and gas-activated reserve type batteries. Reserve battery activation under these various classifications require ancillary components and specific conditions which contribute excess complexity, weight, and volume towards the overall battery design and thus, significant penalties in reliability, specific and volumetric densities are incurred. Improvements in reserve battery technology must include strategies for limiting these penalties through innovated electrolyte delivery designs tailored for modern, high-energy, high-power density lithium-based batteries. Herein, we report a novel electrolyte delivery mechanism facilitated by an electrochemical aperture. The electrochemical aperture serves as a physical barrier, isolating the liquid, lithium-containing electrolyte. Reserve battery activation proceeds via lithium transport, inducing physical transformations via the electrochemical aperture, which permit liquid electrolyte injection into the appropriate compartment(s). Accordingly, ionic conduction between the anode and cathode is established, and ultimately resulting in battery activation and enabling typical battery operation. Strategies for quantifying and reducing activation time via material optimization will be explored. Acknowledgements: Faraday Technology acknowledges the technical assistance of Dr. Joseph P. Fellner at the Air Force Research Laboratory, Wright-Patterson AFB (Dayton, OH) under Air Force Contract No. FA8650-19-P2024 (Phase I SBIR) and FA8650-21-C-2300 (Phase II SBIR). Figure 1

Electrochemical machining (ECM) is a manufacturing technology wherein metal is precisely removed by electrochemical oxidation and dissolution/dispersal into an electrolyte solution. ECM is especially well suited for “difficult to cut” materials (high strength/toughness, work-hardening, etc.) such as high strength steel, chrome-copper alloy (C18200), nickel alloy (IN718), cobalt-chrome alloy (Stellite 25) and tantalum-tungsten alloy (Ta10W) since the material removal process involves no mechanical interaction between the tool and the part. In ECM, an electrochemical cell is established wherein the workpiece is the anode and the tool is the cathode; by relative movement of the shaped tool into the workpiece while applying a suitable electrical voltage, the mirror image of the tool is “copied” into the workpiece. Production of parts with complicated and intricate geometries can thus be achieved in these challenging materials by design of a suitably-shaped tool made from a much more easily-machinable material. Compared to mechanical or thermal machining processes, where metal is removed by cutting or electric discharge/laser machining, respectively, ECM does not suffer from tool wear or result in a thermally damaged surface layer on the workpiece. Additionally, the use of pulse and/or pulse-reverse electrical waveforms can enable successful ECM of even highly passive materials using benign, HF-free electrolytes. Advanced materials such as refractories (e.g., W, Mo, Ta, and their alloys) provide highly desirable characteristics such as high strength, corrosion resistance, and survivability in extreme environments (high temperature, high chemical reactivity, plasma exposure, etc.). As motivation to adopt these materials has increased, conventional fabrication methods have proven progressively less able to successfully machine workpieces of the myriad needed geometries. ECM is a natural non-conventional fabrication method for these materials and workpieces, for the reasons described above. In this talk, we will present results from a proof-of-concept demonstration of pulse-reverse ECM of linear grooves in flat Ta and Ta10W alloy coupons using benign electrolytes, illustrating the potential for cost-effective, safe, environmentally-friendly fabrication using these exotic materials.

Space-borne instruments, such as seeker telescopes, optical sensors, etc., need to minimize stray and reflected light for facilitating space observatory missions. Durable low-reflectivity surfaces/coatings are thus required for suppressing unwanted light within these optical systems. The low-reflectivity coatings need to withstand harsh space environments, including UV radiation, atomic oxygen, vacuum, etc. The excellent mechanical, thermal, optical, and electrical properties of carbon nanotubes (CNTs) make them as ideal coating materials for obtaining low reflectivity surfaces for space applications. In this presentation, Faraday Technology Inc. will discuss an innovative electrophoretic deposition (EPD) manufacturing process, based on the use of pulsed electric fields, for controlled, reproducible, scalable application of low reflective CNT based coatings. The low-reflectivity CNT coatings have been successfully deposited on a variety of geometries: flat coupons, curved surfaces, sharp edges, and internal and external surface of square tubes using the FARADAYIC® EPD process with different anode-cathode configurations (Figure 1 A). The CNT coatings show the total hemispherical reflection of 0.5% - 1% across visible to near infrared (NIR) wavebands, which is much lower than the reflectance of the typically used Z306 black paint (Figure 1 B). Most importantly, the CNT coating shows minimal (~0.14-0.32%) reflectance increase after 5000 equivalent solar hours (ESH) UV/VUV illumination (Figure 1B). As a comparison, Z306 black paint shows ~2.40-4.05 % reflectance increases with same ESH UV/VUV illumination. Figure 1C indicates the CNT coatings has minimal 0-0.0015 (1/sr) BRDF increase in scatter. These CNT coatings also withstood simulated launch conditions vibrational tests, and demonstrated no weight loss and optical degradation. Furthermore, the CNT coatings were evaluated for atomic oxygen erosion resistance in a simulated low earth orbit (LEO) environment, and showed enhanced resilience when compared to Kapton and HOPG. In summary, a scalable manufacturing process for fabricating CNT based coatings with low reflectivity across visible to near infrared wavebands has been demonstrated and shown great potential in facilitating space observatory missions by minimizing stray and reflected light on targeted telescope and baffle materials and construction. The CNT based coatings can also be utilized as broadband absorbers for solar thermal power generation and storage, solar-driven steam generation for sanitization and water purification, and so on. Acknowledgements: The financial support of NASA SBIR program through contracts No. 80NNSC18P2062 & 80NSSC19C0177 is acknowledged. The authors acknowledge Alan Hopkins, Peter Fuqua, and Amber Hennessy from the Aerospace Corporation for simulated launch conditions vibration tests, optical characterization, and UV radiation effect tests. David Oakes and Daniel Hewett from Physical Sciences Inc. are acknowledged for the atomic oxygen erosion tests on the CNT based coatings. Figure 1

In response to the significant plasma science and engineering breakthroughs witnessed over the past decade, the fusion research community has developed an ambitious roadmap to achieve large-scale, energy-positive fusion reactors that will enable economically competitive fusion electricity. Critical to the success of commercial fusion energy is the development of materials able to serve as plasma facing components (PFCs) that can withstand the unprecedented high heat, particle, and neutron fluxes within the fusion reactor. Tungsten is a leading candidate for the plasma-facing portion of these PFCs because of its high melting point, high sputtering resistance, and low tritium retention. Copper or copper-based alloys (e.g., copper-chromium-zirconium alloy C18150) and reduced activation ferritic/martensitic (RAFM) steels have been proposed for the heat sink materials behind the tungsten armor due to their high thermal conductivity. Brazing is considered a promising method for joining the tungsten armor and heat sink layer. However, the extreme mismatch in the coefficient of thermal expansion (CTE) between tungsten and these potential heat sink materials makes directly joining these two layers challenging. This thermal stress can be reduced by incorporating a joining layer of functionally graded materials between the tungsten and heat sink that imparts gradual changes in CTE. Copper/tungsten or copper/tungsten carbide composites are leading candidates for these functionally graded materials. For these composites, gradual changes in the CTE are achieved by varying the volume fraction of tungsten/tungsten carbide in the composite, from tungsten-rich at the tungsten armor to tungsten-poor at the heat sink. This talk will discuss the development of a scalable, electrochemical approach for fabricating interlayers with functionally graded CTE that can decrease the thermal mismatch between tungsten PFCs and copper or RAFM-based heat sinks. In this approach, the copper/tungsten or copper/tungsten carbide composite are electrodeposited onto the tungsten PFC. This component is then bonded to the heat sink via brazing. A key objective of the work is to achieve compositional control during electrodeposition through the use of highly tunable pulse and pulse-reverse electric fields. Engineering of the electric field enables control of the mass transport and crystallization phenomena in the deposition process and thus enables control of composite properties such as composition, porosity, and surface roughness. Results from electrodeposition trials and mechanical testing of brazed joints under ambient conditions as an initial screen for interlayer performance will be discussed, in anticipation of high-heat flux testing of joint performance under fusion-relevant conditions.

Per-/polyfluorinated species (PFAS) are a class of widely used, highly stable chemicals that do not readily break down in the environment or human body. As a result of their widespread use and persistence in the environment, PFAS can be found in soil, air, and water at numerous sites across the United States. Recent work has linked exposure to some types of PFAS found in the environment to adverse health effects in humans. The bio-accumulative nature of PFAS along with the potential adverse health effects has provided strong motivation for active remediation of these emerging contaminants at environmental sites. Development of energy- and cost-efficient technologies for the in-situ treatment of PFAS-contaminated soils would greatly facilitate efforts to remediate these contaminated sites and alleviate the public health threat they represent. This talk will discuss recent efforts to develop a tandem electrokinetic/electrocatalytic technology for energy-efficient concentration and destruction of PFAS in contaminated soils. In this approach (Figure A), electrokinetic soil remediation technology is used to drive the PFAS contaminants to a localized area around the electrokinetic anode and electrocatalysis reactors situated near this electrokinetic anode degrade and destroy the concentrated PFAS species. Data will be presented describing the electrokinetic transport observed for various C 4 -C 12 linear-chain PFAS in a Dayton, OH till soil on the bench scale (see Figure B). Experimental results to date suggest that larger PFAS species (above ~C 6 ) experience sufficiently strong physicochemical attraction to the soil particles that electrokinetic transport is mostly or completely suppressed. Based on these results, current work is identifying ways to improve electrokinetic PFAS remediation by disrupting these PFAS-soil interactions in a fashion that is economically and environmentally favorable. Results demonstrating the ability to enhance electrocatalytic PFAS destruction through the use of pulsed-waveforms (relative to traditional direct current methods) will also be presented. Figure Caption. (A) Mechanism of tandem electrokinetic/electrocatalytic PFAS destruction. (B) Bench-scale apparatus for soil electrokinetics tests. Figure 1

Cellulosic nanomaterials exhibit great potential in various applications due to their unique properties, abundant availability, and low production cost. Although cost effective to produce it is costly to ship, primarily due to the excess of water (>95 wt.%) in growth media necessary to produce the cellulosic nanomaterials. Therefore, a need has been identified by cellulosic material providers to develop energy-efficient, dewatering or drying of cellulosic nanomaterials, “as cellulosic nanomaterials are not economical to ship long distances while containing significant water content”. Moreover, the dewatered or dried cellulosic nanomaterials should be readily re-dispersed in water without any changes in its functional properties. Faraday Technology in collaboration with AVAPCO, answer this need by developing an economical manufacturing method and apparatus for electrochemical dewatering of cellulosic nanomaterials including cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs). Specifically, our innovation is directed towards dewatering of CNCs and CNFs, not drying. AVAPCO has indicated that dewatering to 20-30 wt.% solids would be the end product for numerous applications such as cosmetics and paper processing. Using innovative reactor designs, we demonstrated the feasibility of a cost-effective, industrially viable, and energy efficient ElectroDewatering approach capable of generating 20 wt.% final solids, that was rehydrated under vortex and confirmed for re-dispersibility. Material properties (structure, particle size) were maintained by the dewatered cellulosic nanomaterials. Implementing sophisticated electric fields, we reduced energy use by 50% compared to conventional constant voltage approaches at similar or higher dewatering performance. Specifically, this talk will discuss the results of these advancements. Acknowledgements: The financial support of DOE Contract No. DE-SC0018787 is acknowledged.

Electrophoretic deposition (EPD) is a well-established, scalable industrial manufacturing technology for depositing a wide variety of coatings across a broad range of substrates, geometries and sizes. Conventional electrophoretic deposition (EPD) is the migration of small, suspended particles in a liquid driven by a constant electrical potential difference. As a subset of electrodeposition, EPD has been used to deposit layers on various conducting and semiconducting surfaces from polar, aqueous, and non-polar suspensions. On the other hand, state of the art developments within nanoscience and nanotechnology has opened a new vista for the field of nanocarbon materials. Nanostructured carbon materials, such as carbon nanotubes, graphene, carbon quantum dots, etc., exhibit excellent physical and chemical properties, and have been gaining attention in both fundamental research and technological applications. In this invited presentation, Faraday Technology will discuss an innovative electrophoretic deposition (EPD) manufacturing process, based on the use of pulsed electric fields, for controlled, reproducible, scalable deposition of a wide variety of nanocarbon based coatings across a broad range of substrates, geometries and sizes (Figure 1). The effects of waveforms, electrolytes, substrates, etc. on the formation of robust and uniform coating will be discussed in this talk. The optical and electrical properties, and environmental survivability of nanocarbon coatings will be demonstrated via a variety of testing or characterizations. Faraday will also introduce their applications ranging from low-reflective coatings, solar absorber, high emissivity coatings, to thin film electrodes for energy storage. In summary, a scalable EPD manufacturing process for fabricating nanocarbon based coatings have been developed at Faraday for various applications ranging from optical, thermal, to electrical fields. Acknowledgements: The financial support from NASA SBIR program through contracts No. 80NNSC18P2062 & 80NSSC19C0177, DOD DMEA STTR program through grant No. HQ0727-21-P-0029, DARPA SBIR program through grant No. W31P4Q-22-C-0014, DOD MDA STTR program through grant No. HQ0147-19-C-7065, DOD Air Force SBIR program through grant No. FA9453-19-P-0573, NASA SBIR program through contracts No. 80NSSC20C0287 are acknowledged. Figure 1

Novel technologies with limited earth support are required to enable habitation in microgravity spacecraft habitats such as International Space Station (ISS). Disinfection needs is an area of particular need, which is currently accomplished through the use of pre-packaged, disposable, wetted disinfection wipes. These items represent an appreciable carry-along mass and disposal/replacement burden requiring ground support. Therefore, a system is desired that could utilize onboard utilities to create disinfecting solutions to eliminate storage/disposable problems of the wetted wipes and further reduce the astronaut’s dependence on earth-based supplies. Faraday Technology Inc. is addressing this challenge by demonstrating an in-situ approach, which utilizes on-board supplies of air and water for on demand electrochemical generation of hydrogen peroxide. Hydrogen peroxide is well-established disinfectant with non-toxic decomposition products (viz., O2 and H2O), that is safe enough for human contact to be sold commercially as a 1-5 w/w% solution, which makes it an ideal disinfecting solution for closed space environments. Faraday has continued to improve the TRL by scaling the electrochemical peroxide generation system from a sub-scale to alpha-scale process in order to deliver 1 L per day of ~2 w/w% hydrogen peroxide for disinfectant applications from DI water feed-stream with air as a feed source [1],[2],[3],[4] . These electrolytes were then sent to NASA for microbial control property characterization. Specifically, this talk will discuss the results of these advancements. Acknowledgements: Financial support of NASA Contracts NNX16CA43P, NNX17CJ12C, and 80NSSC20C0070 is acknowledged. References: [1] Vijapur, Santosh H., et al. "Electrochemical peroxide generation." ECS Transactions 77.11 (2017): 947. [2] Vijapur, Santosh, et al. "In-Situ Resource Utilization for Electrochemical Generation of Hydrogen Peroxide for Disinfection." 49th International Conference on Environmental Systems, 2019. [3] Nelson, George J., et al. "Electrochemistry for Space Life Support." The Electrochemical Society Interface 29.1 (2020): 47. [4] Vijapur, Santosh, et al. "In-Situ Resource Utilization for Electrochemical Generation of Hydrogen Peroxide for Disinfection." 50th International Conference on Environmental Systems, 2021.