Component with improved surface contact resistance and reactivity and method of manufacturing thereof

Abstract

A component having improved surface contact resistance and reactivity and a method of making the same are disclosed, falling within the technical field of surface contact resistance and reactivity components. The component includes: a metal base; and a plurality of particles bonded to a surface of the metal base by a metallurgical bond; wherein the plurality of particles includes a metal, carbon, or a combination thereof, wherein the metallurgical bond is between the plurality of particles and the metal base, wherein a total projected area of the metallurgical bond is less than 90% of a total projected area of the metal base, and wherein a composition of the metallurgical bond is a combination of a composition of the metal base and a composition of the plurality of particles, a reaction product of the metal base and the plurality of particles, or a combination thereof.

Description

[0001] Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Application No. 62 / 891,879, filed February 26, 2020, and all benefits arising therefrom under 35 U.S.C. § 119, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] A component having improved surface contact resistance and reactivity and a method of making the same are disclosed. For example, the component can be a bipolar plate or electrode for a battery, fuel cell, or electrolyzer. BACKGROUND

[0004] In fuel cell, flow battery, or electrolyzer applications, bipolar plates are used to connect adjacent cells. It is desirable for the bipolar plates to have low surface contact resistance and strong corrosion resistance to minimize internal ohmic losses and maintain operational stability over the service life. In electrolyzers or flow batteries, electrodes with high reactivity are needed to carry out efficient electrode reactions. There is still a need for improved components, such as bipolar plates with improved combination of contact resistance and corrosion resistance or electrodes with high reactivity. SUMMARY

[0005] A component having improved surface contact resistance and reactivity is disclosed, the component comprising: a metal substrate; and a plurality of particles bonded to a surface of the metal substrate by a metallurgical bond, wherein the plurality of particles comprises a metal, carbon, or a combination thereof, wherein the metallurgical bond is between the plurality of particles and the metal substrate, wherein a total projected area of the metallurgical bond is less than 90% of a total projected area of the metal substrate, and wherein a composition of the metallurgical bond is a combination of a composition of the metal substrate and a composition of the plurality of particles, a reaction product of the metal substrate and the plurality of particles, or a combination thereof.

[0006] A method of making a component having improved surface contact resistance and reactivity, the method comprising: providing a metal substrate; depositing a mixture comprising a plurality of precursor particles onto the metal substrate, wherein the plurality of precursor particles comprises a metal, carbon, a metal hydride, or a combination thereof, to form a coated metal substrate, wherein the plurality of precursor particles contacts less than 90% of the total projected area of the metal substrate, and wherein the plurality of precursor particles has an average particle size of less than 200 μm; and heat treating the coated metal substrate to form particles from the plurality of precursor particles and bond the particles to the metal substrate through a metallurgical bond formed between the particles and the metal substrate to make the component, wherein the metallurgical bond is a combination of the metal substrate composition and the particle composition, a reaction product of the metal substrate and the particles, or a combination thereof. BRIEF DESCRIPTION OF DRAWINGS

[0007] The above and other advantages and features of the present disclosure will become more apparent from the following description of the embodiments of the present disclosure when taken in conjunction with the accompanying drawings, in which:

[0008] Figure 1 is a schematic cross-sectional view of a metal substrate comprising a plurality of particles metallurgically bonded to the metal substrate;

[0009] Figure 2 is a schematic cross-sectional view of a porous coating on a metal substrate;

[0010] Figure 3 is a schematic cross-sectional view of two substrates and a metallurgical bond formed between the substrates through particles;

[0011] Figure 4 is a photograph of a stamped stainless steel bipolar plate for a fuel cell;

[0012] Figure 5 is a cross-section of a stainless steel bipolar plate;

[0013] Figure 6 is an SEM photograph of glassy carbon spherical particles metallurgically bonded to a titanium substrate;

[0014] Figure 7 is a plot of contact resistance (milliohms-sq. cm, mΩ-cm 2 ) versus compressive pressure (pounds per square inch, PSI) showing a comparison of surface contact resistance with carbon felt with and without metallurgically bonded carbon particles on the surface of a titanium plate;

[0015] Figure 8 is an SEM photograph of graphite particles metallurgically bonded to a titanium substrate;

[0016] Figure 9is an SEM photograph of a composite of titanium particles and milled carbon fiber particles metallurgically bonded to a stainless steel mesh;

[0017] Figure 10 is an SEM photograph showing the microstructure of a composite of titanium particles and milled carbon fiber particles;

[0018] Figure 11 is an SEM photograph of titanium particles metallurgically bonded to a titanium substrate; and

[0019] Figure 12 is an SEM photograph of a porous titanium coating on a titanium substrate. DETAILED DESCRIPTION

[0020] The present application will now be described more fully hereinafter with reference to the accompanying drawings, in which various embodiments are shown. The present application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art. Like reference numerals refer to like elements throughout.

[0021] In a fuel cell, flow battery, or electrolyzer stack, components between adjacent cells (e.g., bipolar plates) are required to maintain electrical connection of adjacent cells and to separate reactants in adjacent cells. Bipolar plates maintain electrical contact with other components in an electrolyzer stack (e.g., mass transport layers or electrodes). However, surface contact between solids only occurs at the high points of the surfaces. Thus, the number of contact points or the contact area is limited, which results in a higher surface electrical or thermal contact resistance. One method to reduce surface contact resistance is to use a soft material on the contact surface. Soft materials can deform under pressure to match the surface topography of the contacting components, increasing the actual contact area between the two components. Representative soft materials that enhance electrical or thermal contact include silver, gold, or tin. However, such soft materials are either too expensive or do not provide suitable chemical stability or corrosion resistance for electrochemical devices such as fuel cells or electrolyzers.

[0022] U.S. Patent 10,435,782 discloses modifying the surface topography to provide a micro-textured structure of a corrosion resistant material to reduce electrical contact resistance. The actual contact area between components is increased by deformation of the micro-textured structure under compressive pressure, resulting in lower contact resistance. However, developing a low cost, rapid manufacturing process to provide such micro-textured structures for high volume production has proven difficult. For example, utilizing pulsed lasers to provide micro- or nano-scale surface structures has proven too inefficient and expensive for commercial applications.

[0023] U.S. Patent Application 2018 / 0309136 teaches mechanically bonding particles to a substrate using electrostatic forces in a vacuum. Further evaluation found that the mechanical bond interface between the plurality of particles and the metal substrate was susceptible to corrosion along the interface, which ultimately led to bond failure.

[0024] Adhesive bonding and brazing were also considered, but it was found that the resulting bonds did not provide suitable corrosion resistance for electrochemical applications. Diffusion bonding was also considered, in which the components are pressed together under high pressure and high temperature. However, diffusion bonding has proven to be expensive and does not provide suitable corrosion resistance.

[0025] In electrolytic cells or flow batteries, electrode activity affects power and efficiency. A common method to increase reaction activity is to employ high activity materials and increase surface area. Due to the highly corrosive operating environment in electrochemical devices, the bond between the electrode reaction activity material and the electrode substrate, which is typically metal, needs to be improved to maintain long term durability of the electrode.

[0026] The inventors have surprisingly found that if a plurality of particles are bonded to a metal substrate by a metallurgical bond, improvements in the combined properties of contact resistance, reaction activity, and corrosion resistance can be achieved, while at the same time resulting in a component, such as a bipolar plate, that has improved performance in electrochemical applications, such as in a fuel cell, flow battery, or electrolytic cell.

[0027] A component having improved surface contact resistance and reaction activity is disclosed, the component comprising: a metal substrate; a plurality of particles bonded to a surface of the substrate by a metallurgical bond, wherein the plurality of particles comprises a metal, carbon, or a combination thereof, wherein the metallurgical bond is between the particles and the substrate, wherein a total projected area of the metallurgical bond is less than 90% of a total projected area of the substrate, and wherein a composition of the metallurgical bond is a combination of a composition of the metal substrate and a composition of the plurality of particles, a reaction product of the metal substrate and the plurality of particles, or a combination thereof.

[0028] Figure 1 One aspect of the disclosed component is shown, which shows a metal substrate 11 and particles 12 bonded to the metal substrate by a metallurgical bond 13. In one aspect, a metallurgical bond can be formed between the particles in addition to the metallurgical bond between the particles and the substrate.

[0029] The metal substrate can comprise a Ti metal, a Nb metal, a Ta metal, a Ni metal, a Cr metal, an alloy of the foregoing metals, a stainless steel, or a combination of the foregoing metals. The use of Ti or stainless steel (e.g., 316 or 304 stainless steel) is mentioned. The metal substrate can have any suitable form and be fully dense or porous, and can be in the form of a thin film, a foil, a separator, a mesh, a perforated thin film, an expanded metal foil, or a microporous sheet.

[0030] In one aspect, expanded metal, screen mesh, perforated metal, or wire mesh can be used as the metal substrate. The open area of the metal substrate can be 10% to 90%, 20% to 80%, 30% to 70%, or 40% to 60% of the total projected area of the metal substrate. For example, multiple layers of the above materials can be employed to form a multilayered metal substrate having a structural or compositional gradient. The use of titanium felt or titanium sinter is mentioned. In one aspect, a microporous sheet can be employed, and the porosity can be 30% to 95%, 40% to 90%, 50% to 85%, or 55% to 80% based on the volume of the metal substrate. Any suitable combination of the upper and lower limits of the above ranges can be employed.

[0031] In one aspect, the plurality of particles includes a metal or carbon. In one aspect, the plurality of particles includes a metal, wherein the metal is a Ti metal, a Nb metal, a Ta metal, a Ni metal, a Cr metal, an alloy of the foregoing metals, or a combination of the foregoing metals. The use of Ti particles is mentioned. In one aspect, the plurality of particles can include intermetallic compounds of Ti metal, Nb metal, Ta metal, Ni metal, and Cr metal, hydrides of Ti metal, Nb metal, Ta metal, Ni metal, and Cr metal, or a combination thereof. The fracture properties of the intermetallic compounds or hydrides help to form particles of suitable size. Figure 11 An SEM photo of Ti particles metallurgically bonded to a titanium substrate is shown. The smooth edges of the metal substrate with the plurality of particles is an indication of the diffusion bonding between the Ti particles and the titanium substrate. It also shows the bonding between the Ti particles to form a cluster of particles.

[0032] The plurality of particles can have an average particle size of less than 200 micrometers (pm), such as from 3 nanometers (nm) to 200 pm, from 8 nm to 150 pm, from 10 nm to 100 pm, from 50 nm to 50 pm, or from 500 nm to 10 pm. Particles having an average particle size of from 3 nm to 200 pm, from 0.1 to 5 pm, from 3 nm to 8 nm, from 5 nm to 10 nm, from 7 nm to 100 nm, from 50 nm to 500 nm, from 10 nm to 20 pm, from 5 nm to 0.5 pm, from 20 nm to 1 pm, from 100 nm to 0.9 pm, from 20 nm to 5 pm, from 100 nm to 2 pm, from 0.5 pm to 5 pm, from 1 pm to 10 pm, from 5 pm to 20 pm, from 10 pm to 50 pm, from 20 pm to 70 pm, from 50 pm to 100 pm, from 70 pm to 170 pm, or from 150 pm to 200 pm are mentioned. Any suitable combination of the upper and lower limits of the ranges mentioned above can be employed. The plurality of particles can have any suitable shape, and can be spherical, ellipsoidal, or in the form of fibers. Further, the plurality of particles can be primary particles or agglomerates, such as secondary particles. Metal particles having an average particle size of from 50 nm to 10 pm are mentioned, such as titanium particles having an average particle size of from 100 nm to 5 pm. While not wishing to be bound by theory, it is understood that small particles (e.g., particles having an average particle size of from 100 nm to 5 pm) can achieve metallurgical bonding more quickly and at lower temperatures or pressures than when larger particles are employed.

[0033] In one aspect, the plurality of particles includes carbon particles. The carbon particles can be amorphous carbon, graphite, carbon fibers, or a combination thereof. While not wishing to be bound by theory, it is understood that when carbon is employed, the metallurgical bond includes carbides formed from the reaction between the carbon particles and the metal. Further, because of the high reactivity of carbon with metals, larger particles can be employed. It is mentioned that carbon particles having an average particle size of less than 200 μm are employed. The average particle size of these carbon particles can be from 50 nm to 500 nm, from 100 nm to 1 μm, from 500 nm to 2 μm, from 1 μm to 5 μm, from 1 μm to 10 μm, from 5 μm to 20 μm, from 10 μm to 50 μm, from 20 μm to 70 μm, from 50 μm to 100 μm, from 70 μm to 170 μm, or from 150 μm to 200 μm. Any suitable combination of the upper and lower limits of the ranges described above can be employed. The carbon can be in the form of fibrous particles. The fibrous particles can have a fiber diameter of from 3 nm to 20 μm, preferably from 1 to 10 μm. The carbon fibers can have a diameter of from 3 nm to 8 nm, from 5 nm to 10 nm, from 7 nm to 100 nm, from 50 nm to 500 nm, from 10 nm to 20 μm, from 5 nm to 0.5 μm, from 20 nm to 1 μm, from 100 nm to 0.9 μm, from 20 nm to 5 μm, from 100 nm to 2 μm, from 0.5 μm to 5 μm, from 1 μm to 10 μm, or from 5 μm to 20 μm. Any suitable combination of the upper and lower limits of the ranges described above can be employed.

[0034] In one aspect, prior to the metallurgical bonding, the metal substrate and the plurality of particles have a coating applied to the surface. The coating is used to enhance the corrosion resistance and bonding activity of the metal substrate and the plurality of particles. The metallurgical bond can be formed with the coating material.

[0035] The dimensions (e.g., length) of the metallurgical bond formed between the plurality of particles and the metal substrate can correspond to the particle size. For example, the average length of the metallurgical bond can be less than 200 μm, such as from 3 nm to 200 μm, from 8 nm to 150 μm, from 10 nm to 100 μm, from 50 nm to 50 μm, or from 500 nm to 10 μm. Further, the area of the metallurgical bond formed between the plurality of particles and the metal substrate can be less than 200 μm 2 , such as from 3 nm 2 to 200 μm 2 , from 8 nm 2 to 150 μm 2 , from 10 nm 2 to 100 μm 2 , from 50 nm 2 to 50 μm 2 , or from 500 nm 2 to 10 μm 2 .

[0036] While not wishing to be bound by theory, it is understood that employing a quantity of the plurality of particles to cover a portion of the total projected area of the metal substrate facilitates the formation of a metallurgical bond having desired properties. While not wishing to be bound by theory, it is believed that by employing a content of the plurality of particles to cover less than 90% of the total area of the substrate, thermal stresses during the formation of the metallurgical bond and application of the part can be reduced even when there is a significant mismatch between the coefficients of thermal expansion of the plurality of particles and the metal substrate. As used herein, the term "projected area" refers to a two-dimensional area determined in a plan view, regardless of the modularity or porosity that the substrate can have. In one aspect, there is reference to employing a quantity of particles to cover less than 90% or 1% to 90%, 10% to 80%, 20% to 70%, 30% to 70%, or 40% to 50% of the total projected area of the substrate. The area of the metallurgical bond between the plurality of particles and the metal substrate can be less than 90% or 1% to 90%, 10% to 80%, 20% to 70%, 30% to 70%, or 40% to 50% of the total projected area of the metal substrate. Any suitable combination of the upper and lower limits of the ranges described above can be employed.

[0037] In one aspect, where the plurality of particles cover less than 90% of the total projected area of the metal substrate, adjacent plurality of particles can be separated by a distance, for example, an average distance of 5 nm to 200 μιη, for example, 5 nm to 10 nm, 7 nm to 100 nm, 50 nm to 500 nm, 10 nm to 20 μιη, 5 nm to 0.5 μιη, 20 nm to 1 μιη, 100 nm to 0.9 μιη, 20 nm to 5 μιη, 100 nm to 2 μιη, 0.5 μιη to 5 μιη, 1 μιη to 10 μιη, 5 μιη to 20 μιη, 10 μιη to 50 μιη, 20 μιη to 70 μιη, 50 μιη to 100 μιη, 70 μιη to 170 μιη, or 150 μιη to 200 μιη. Any suitable combination of the upper and lower limits of the ranges described above can be employed.

[0038] The plurality of particles can further include ceramic particles, where the ceramic particles include carbides, oxides, nitrides, silicides, or combinations thereof. While not wishing to be bound by theory, it is understood that by including ceramic particles, the ceramic particles can bond to the metallic particles described above, resulting in a reduction in thermal stresses. Representative carbides include titanium carbide, niobium carbide, silicon carbide, tantalum carbide, tungsten carbide, iron carbide, chromium carbide, or zirconium carbide. Representative oxides include aluminum oxide, titanium oxide, niobium oxide, tantalum oxide, zirconium oxide, cerium oxide, silicon dioxide, tungsten oxide, or cerium oxide. Representative nitrides include titanium nitride, chromium nitride, aluminum nitride, zirconium nitride, tungsten nitride, vanadium nitride, tantalum nitride, or niobium nitride. Representative silicides include nickel silicide, niobium silicide, titanium silicide, molybdenum silicide, or tungsten silicide. Combinations including at least one of the above materials can be employed. The use of aluminum oxide is mentioned.

[0039] In one aspect, the plurality of particles bonded to the metallic substrate forms a porous coating layer, as Figure 2 The figure shows a metallic substrate 21 and a porous coating layer 22 including metallurgically bonded particles. The porous coating layer can have an average pore size of 3 nm to 100 μιη, such as 3 nm to 100 μιη, 10 nm to 50 μιη, or 50 nm to 500 nm. The use of a pore size of 3 nm to 7 nm, 5 nm to 10 nm, 7 nm to 20 nm, 50 nm to 500 nm, 10 nm to 20 μιη, 5 nm to 0.5 μιη, 20 nm to 1 μιη, 100 nm to 0.9 μιη, 20 nm to 5 μιη, 100 nm to 2 μιη, 0.5 μιη to 5 μιη, 1 μιη to 10 μιη, 5 μιη to 20 μιη, 10 μιη to 50 μιη, 20 μιη to 100 μιη, or 50 μιη to 100 μιη is mentioned. In one aspect, the porous coating layer 22 has a thickness in the range of 1 μιη to 1 millimeter (mm), such as 1 μιη to 10 μιη, 5 μιη to 20 μιη, 10 μιη to 100 μιη, 50 μιη to 200 μιη, 100 μιη to 500 μιη, 200 μιη to 800 μιη, 500 μιη to 1000 μιη, or 700 μιη to 1 mm. Any suitable combination of the upper and lower limits of the ranges described above can be employed. While not wishing to be bound by theory, it is understood that the metallurgical bonding of the plurality of particles to the metallic substrate results in a reduction in shrinkage, for example, by limiting the shrinkage of the plurality of particles in the vertical direction (e.g., the direction normal to the surface of the substrate) and reducing or eliminating shrinkage in the in-plane direction of the substrate (e.g., the direction along the surface of the substrate). By eliminating shrinkage in the in-plane direction, the porous coating layer 22 can be formed to conform to the shape and structure of the metallic substrate without distortion. Further, the particle deposition and bonding process can be applied multiple times to form a multi-layered porous structure to form a porous layer of increasing thickness. Figure 12 An example is shown, which is an SEM photograph of a porous titanium coating on a titanium substrate surface.

[0040] In one aspect, a second substrate can be provided and combined with the particulate metallurgy. For example, the second substrate can be a mass transport layer for a fuel cell or electrolyzer. Figure 3 A component is shown having a metal substrate 31 A, a second substrate 31 B, and a discontinuous bond layer 32 between the metal substrate 31 A and the second substrate 31 B. The discontinuous bond layer 32 includes particles 33 that are bonded to the first substrate 31 A by a first metallurgical bond 34A and to the second substrate 32A by a second metallurgical bond 34B. The thickness of the discontinuous bond layer 32 ranges from 1 μιη to 0.5 mm, such as 1 μιη to 500 μιη, 5 μιη to 200 μιη, or 10 μιη to 100 μιη. Any suitable combination of the upper and lower limits of the ranges described above can be employed. As shown, the particles are disposed between the metal substrates that are bonded together by the particles and the metallurgical bonds to form a continuous bond with the particles in a direction normal to the metal substrates and discontinuous in an in-plane direction. Figure 3

[0041] The second substrate can be the same as or different from the metal substrate. The second substrate can include carbon or a Ti metal, a Nb metal, a Ta metal, an Al metal, a Ni metal, a Cr metal, an alloy of the foregoing metals, stainless steel, or a combination of the foregoing metals. The second substrate can have a suitable form and be fully dense or porous, and can be in the form of a thin film, foil, separator, screen, perforated film, expanded metal foil, or microporous plate. In one aspect, the second substrate includes carbon and can be a porous non-woven carbon paper. In one aspect, the second substrate can include a metal and can be an expanded metal substrate, such as a wire mesh or screen.

[0042] Figure 4 and Figure 5 ​An example of a metal substrate for a fuel cell is shown, where a fuel cell bipolar plate is shown. To form the bipolar plate, a stainless steel foil is stamped with flow field channels 41, including land regions 52 and valley regions 51. The land regions 52 will be in electrical contact with a second substrate, for example, a gas diffusion layer (GDL). It can be desirable to form deeper channels to improve water management. However, due to limitations in the properties of the metal foil, such as elongation, it is difficult to obtain deep channels by stamping alone. The channel depth can be increased by adding a thicker porous granular coating on top of the land regions 52. The granules can be metal only or a mixture of metal and carbon granules. The granules are deposited on the land regions, and the bipolar plate with the granules on the land regions 52 is heat treated to bond the granules to the substrate to form a substrate with flow channels and a thicker porous coating on the land regions. The thickness of the porous coating is between 0.01 mm and 0.5 mm, for example, 0.01 mm to 0.05 mm, 0.02 mm to 0.1 mm, 0.05 mm to 0.2 mm, 0.1 mm to 0.3 mm, or 0.2 mm to 0.5 mm. Titanium granules are mentioned for the thicker porous coating on the land regions 52. It is also mentioned that a mixture of titanium and carbon powders is used to achieve a reduction in the surface contact resistance.

[0043] If desired, additional coatings can be provided to alter the surface properties. For example, without additional coatings, the component can have a superhydrophilic water contact angle, for example, a water contact angle of less than 90°, for example, 5° to 40°, 10° to 20°, or less than 15°. In one aspect, a hydrophobic material, such as polytetrafluoroethylene, can be applied to the porous surface layer to form a superhydrophobic surface having a contact angle greater than 150°, for example, 170°.

[0044] In one aspect, a porous metal layer is used as a mass transport layer in an electrolytic cell. The pore size ranges from 20 μm to 500 μm. The use of porous titanium particle sintered material or titanium felt is mentioned. Generally, large pores favor gas transport, while small pores favor water transport through the mass transport layer. However, in conventional manufacturing processes, it is difficult to simultaneously achieve both small (less than 1 μm) and large pore sizes. In the components disclosed in this invention, a microporous metal coating is added to the core structure of the large-pore metal mass transport layer to form a hybrid porous layer containing both micro- and large-pore sizes. The pore size of the microporous coating ranges from 3 nm to 1 μm. It can absorb water through capillary action in the micron-sized pores to maintain a continuous water supply to the electrodes and allow gas to flow through the large pores. The capillary action of water in the micron-sized pores prevents gas from penetrating the microporous coating, thus achieving an uninterrupted water supply. In the hybrid porous structure, gas and water are transported through their respective paths. The particle size of the microporous coating can be 3nm to 2μm, preferably 10nm to 1μm, for example 3nm to 8nm, 5nm to 10nm, 7nm to 100nm, 50nm to 500nm, 10nm to 1μm, 200nm to 2μm or 0.5μm to 2μm.

[0045] As discussed further below, the component can be tested at 80°C and 0.8V in a pH 3 solution of H₂SO₄ containing 0.1 ppm HF. NHE After processing, the surface contact resistance was assessed using carbon paper (e.g., AvCarb MGL 190) at a compression pressure of 200 PSI, as defined in the Department of Energy's (DOE) Office of Hydrogen and Fuel Cell Technologies' Multi-Year Research, Development and Demonstration Program (https: / / www.energy.gov / eere / fuelcells / downloads / hydrogen-and-fuel-cell-technologies-office-multi-year-research-development), the entire contents of which are incorporated herein by reference. When evaluated according to the DOE method, the disclosed components can have a resistance from 0.1 to 10 mΩ·cm. 2 5 to 8 mΩ·cm 2 Or 1 to 5 mΩ·cm 2 The surface contact resistance is adjusted to meet the requirements of fuel cell applications.

[0046] A method of making a component for an electrochemical device is also disclosed, the method comprising: providing a metal substrate; depositing a mixture comprising a plurality of precursor particles on the metal substrate, wherein the plurality of precursor particles comprises a metal, carbon, a metal hydride, or a combination thereof, to form a coated substrate, wherein the plurality of precursor particles contacts less than 90% of the total projected area of the metal substrate, and wherein the plurality of precursor particles has an average particle size of less than 200 μm; and heat treating the coated substrate to form particles from the plurality of precursor particles and bond the particles to the metal substrate through a metallurgical bond formed between the particles and the metal substrate to make the component, wherein the metallurgical bond is a combination of a metal substrate component and a particle component, a reaction product of the metal substrate and the particles, or a combination thereof.

[0047] The plurality of precursor particles comprises a metal, carbon, a metal hydride, or a combination of Ti, Nb, Ta, Ni, Cr, an alloy thereof, or a combination thereof. Alloys or intermetallic compounds of Ti, Nb, Ta, Ni, or Cr are mentioned. In one aspect, the plurality of precursor particles comprises titanium hydride. The use of a combination of titanium particles and carbon particles to form a metallurgical bond comprising titanium carbide is mentioned. The plurality of precursor particles can have a particle size of less than 200 micrometers (μm), such as from 3 nanometers (nm) to 200 μm, from 8 nm to 150 μm, from 10 nm to 100 μm, from 50 nm to 50 μm, or from 500 nm to 10 μm. The plurality of precursor particles on the metal substrate can be present in an amount that covers from 1% to 90%, from 6% to 80%, from 10% to 70%, from 20% to 60%, or from 40% to 50% of the total projected area of the metal substrate. Any suitable combination of the upper and lower limits of the ranges mentioned above can be used.

[0048] Any suitable combination of the upper and lower limits of the ranges mentioned above can be used. In one aspect, a combination of precursor particles is used. While not wishing to be bound by theory, it is understood that the use of particles having different melting temperatures can form a reduced shrinkage metallurgical bond at lower temperatures, e.g., particles having a lower melting temperature can bind particles having a higher melting temperature and the metal substrate.

[0049] The mixture of precursor particles can further comprise a plurality of ceramic particles, wherein the ceramic particles comprise carbides, oxides, nitrides, or a combination thereof, as further described above. While not wishing to be bound by theory, it is understood that shrinkage can be reduced when ceramic particles are used.

[0050] The mixture comprising precursor particles can be deposited on the metal substrate by any suitable method. Dry powder deposition is disclosed, or use of coating or tape casting using a carrier or vehicle such as an organic solvent. Dry powder deposition can include dry powder electrostatic deposition of the precursor particles. During electrostatic deposition, the particles can be charged and the charged particles can be deposited on the metal substrate under an applied electric field. While not wishing to be bound by theory, it is understood that electrostatic deposition can be desirable for reducing particle agglomeration and forming a more uniform layer of particles on the substrate. Alternatively, the precursor particles can be dispersed in a solvent including a binder to form a slurry, the slurry is coated onto the substrate. The binder can include binders used in ceramic processes such as polyvinyl butyral or polyethylene carbonate. Other details of the coating process can be determined by one skilled in the art without undue experimentation.

[0051] In one aspect, the heat treatment can be performed at a temperature below the melting temperature of the particles and below the melting temperature of the metal substrate or the second substrate. While not wishing to be bound by theory, it is understood that a metallurgical bond is formed during the heat treatment at the particle-substrate contact points by interdiffusion or chemical reaction of the particle and the substrate, thereby forming a metallurgical bond at the interface of the particle and the substrate, bonding the particle to the substrate. The heat treatment can include a heat treatment performed at a temperature of 300°C to 1200°C (e.g., 400°C to 1000°C, 800°C or less). Preferably, a bonding temperature of 800°C or less can be employed to avoid deformation of the metal substrate. In one aspect, it is mentioned that a temperature at least 500°C lower than the melting temperature of the metal substrate is employed to avoid deformation of the substrate. Avoiding deformation can be advantageous when the component (e.g., bipolar plate) includes structural features such as flow channels. Further, while not wishing to be bound by theory, it is believed that the particle size of the present disclosure allows for formation of the metallurgical bond in a shorter time (e.g., 0.001 hours to 20 hours, 0.01 hours to 10 hours, or 0.1 hours to 5 hours). The heat treatment can include a furnace heat treatment, or can include a laser heat treatment, an electron beam heat treatment, an infrared (IR) heat treatment, or a plasma heat treatment. In laser heating, a high intensity laser beam is used to scan the metal substrate having the plurality of precursor particles deposited thereon and heat the metal substrate surface to form the metallurgical bond and bond the particles to the metal substrate. In another embodiment, a high intensity IR lamp is employed. It is mentioned that heating is performed using electron beam heating to achieve rapid heating.

[0052] The heat treatment can include a heat treatment performed in a vacuum or in a non-oxidizing atmosphere (e.g., in argon, helium, or a combination thereof).

[0053] The method can further include pressing the coated substrate at a pressure of 1 pound per square inch (PSI) to 500 PSI, 20 PSI to 400 PSI, or 50 PSI to 100 PSI. If a second substrate is employed, the pressing can include applying pressure to the metal substrate and the second substrate to compress the particles.

[0054] In one aspect, the textured carbon coating is obtained by a single step of melting the carbon particles and simultaneously depositing the melted particles. Because the melting temperature of carbon is very high (about 3550 °C), a high temperature is employed to melt the carbon particles. The high temperature heat source can be a plasma, a high power pulsed laser, or an electric arc. At the high temperature, the carbon particles will be partially evaporated, and the resulting coating can have a textured structure that includes carbon protrusions covering a small portion of the substrate surface, and the rest of the surface is covered by a thin film of carbon coating.

[0055] As used herein, "metallurgical bond" is a chemical bond between two solid materials (including at least one metallic material) formed at high temperature. It has two types of bonds. One is a diffusion bond, a continuous connection formed by interdiffusion of two materials at high temperature. The other is a reaction bond, a reaction between two materials at the contact site, generating a reaction product that connects the two materials together. Both types of metallurgical bonds generate an atomic-level mixture of the two materials and can extend the contact of the two materials from a point to a surface / interface contact. The atomic-level mixture and the larger contact area ensure a durable bond between the two materials.

[0056] In one aspect, the composition of the metallurgical bond is a combination of the metal substrate composition and the particle composition, a reaction product of the metal substrate and the particle, or a combination thereof. The composition of the metallurgical bond can be a combination of the metal substrate composition and the particle composition. In one aspect, the metallurgical bond includes a reaction product of the particle, a reaction product of the particle and the substrate, or a combination thereof.

[0057] The thickness of the metallurgical bond can be 0.5 nm to 50 pm, such as 0.5 nm to 5 nm, 1 nm to 10 nm, 5 nm to 50 nm, 10 nm to 50 nm, 10 nm to 100 pm, 50 nm to 0.2 pm, 100 nm to 1 pm, 500 nm to 5 pm, 20 nm to 5 pm, 1 pm to 10 pm, 5 pm to 20 pm, 10 pm to 50 pm, or 20 pm to 50 pm. Any suitable combination of the upper and lower limits of the ranges described above can be employed.

[0058] In the method, the heat treated component can be cleaned to, for example, remove unbound particles. The cleaning can include contacting the heat treated component with a fluid (e.g., air or water), and can include, for example, ultrasonic water bath cleaning or pickling.

[0059] As used herein, "average particle size" refers to the particle size corresponding to 50% of the particles in a distribution curve, where the particles are aggregated in order of particle size from smallest to largest, and the total number of aggregated particles is 100%. The average particle size can be measured by methods known to those skilled in the art. For example, the average particle size can be measured using a particle size analyzer (e.g., dynamic light scattering), or can be measured using a transmission electron microscope (TEM) or a scanning electron microscope (SEM).

[0060] A component for an electrochemical device is disclosed, the component comprising: a metal substrate; a plurality of particles bonded to a surface of the metal substrate by a metallurgical bond, wherein the plurality of particles comprises a metal, carbon, or a combination thereof, wherein the metallurgical bond is between the plurality of particles and the metal substrate, wherein a total projected area of the metallurgical bond is less than 90% of a total projected area of the metal substrate, and wherein a composition of the metallurgical bond is a combination of a composition of the metal substrate and a composition of the plurality of particles, a reaction product of the metal substrate and the plurality of particles, or a combination thereof.

[0061] A method of manufacturing a component for an electrochemical device is also disclosed, the method comprising: providing a metal substrate; depositing a mixture comprising a plurality of precursor particles on the metal substrate, wherein the plurality of precursor particles comprises a metal, carbon, a metal hydride, or a combination thereof, to form a coated metal substrate, wherein the plurality of precursor particles contacts less than 90% of a total projected area of the metal substrate, and wherein an average particle size of the plurality of precursor particles is less than 200 μιη; and heat treating the coated metal substrate to form particles from the plurality of precursor particles and bond the particles to the metal substrate by a metallurgical bond formed between the particles and the metal substrate to make the component, wherein a composition of the metallurgical bond is a combination of a composition of the metal substrate and a composition of the particles, a reaction product of the metal substrate and the particles, or a combination thereof.

[0062] In any of the above embodiments, the metal substrate may include Ti metal, Nb metal, Ta metal, Ni metal, Cr metal, alloys of the aforementioned metals, stainless steel, or combinations of the aforementioned metals; the plurality of particles may include metal, and the metal may be Ti, Nb, Ta, Ni, Cr, their alloys, or combinations thereof; the average particle size of the plurality of particles may be less than 20 μm; the plurality of particles may be metal particles with an average particle size of 50 nm to 10 μm; the plurality of particles may be Ti particles with an average particle size of 100 nm to 5 μm; the plurality of particles may include carbon, and the carbon may be amorphous carbon, graphite, carbon fiber, or combinations thereof, wherein the average particle size of the carbon is less than 200 μm; the total projected area of ​​the metallurgical bond may be 1% to 70% of the total projected area of ​​the metal substrate; optionally, it may also include a plurality of ceramic particles on the metal substrate, wherein the ceramic particles include carbides, oxides, nitrides, silicides, or combinations thereof; optionally, the component may be a bipolar plate for a fuel cell or electrolyzer; in a pH3 solution of H2SO4 and 0.1 ppm HF at 80°C and 0.8V. NHE After 100 hours of treatment, the bipolar plate exhibits a resistance of less than 10 mΩ·cm under a compressive pressure of 200 PSI. 2surface electrical contact resistance; optionally, the component can be an electrode for an electrolytic cell or a flow battery; optionally, further comprising a second substrate on a side of the plurality of particles opposite the metal substrate, wherein the second substrate comprises carbon or a Ti metal, a Nb metal, a Ta metal, a Ni metal, a Cr metal, an alloy of the foregoing metals, a stainless steel, or a combination of the foregoing metals, wherein the plurality of particles are bonded to the second substrate by a second metallurgical bond between the plurality of particles and the second substrate, wherein a projected area of the second metallurgical bond is less than 90% of a total projected area of the second substrate, and wherein a composition of the second metallurgical bond is a combination of a composition of the second substrate and a composition of the plurality of particles, a reaction product of the second substrate and the plurality of particles, or a combination thereof; the metal substrate and the second substrate can have the same composition; the second substrate can comprise a multi-layer having a structural or compositional gradient; the second substrate can be a wire mesh having an open area of 10% to 90% based on a total projected area of the second substrate; the second substrate can be a porous mass transport layer having a porosity of 30% to 95%; optionally, the electrochemical device can be a fuel cell, a battery, an electrolytic cell, or a capacitor; the metal substrate can comprise a Ti metal, a Nb metal, a Ta metal, an Al metal, a Ni metal, a Cr metal, an alloy of the foregoing metals, a stainless steel, or a combination of the foregoing metals; the plurality of precursor particles can comprise a Ti metal, a Nb metal, a Ta metal, an Al metal, a Cr metal, an alloy of the foregoing metals, an intermetallic compound of the foregoing metals, a hydride thereof, or a combination thereof, and have an average particle size of 50 nm to 20 pm; the plurality of precursor particles can comprise carbon particles having an average particle size of less than 200 pm; the plurality of precursor particles can cover 3% to 90% of a total projected area of the metal substrate; the heat treatment can comprise a heat treatment performed in a vacuum or a non-oxidizing atmosphere, and wherein the heat treatment comprises electron beam surface heating or laser surface heating; the composition can further comprise a plurality of ceramic particles, wherein the ceramic particles comprise carbides, oxides, nitrides, or a combination thereof; optionally, further comprising a second substrate on a side of the plurality of particles opposite the metal substrate, wherein the second substrate comprises carbon or a Ti metal, a Nb metal, a Ta metal, a Ni metal, a Cr metal, an alloy of the foregoing metals, a stainless steel, or a combination of the foregoing metals, and wherein the plurality of particles are bonded to the second substrate by a second metallurgical bond between the plurality of particles and the second substrate, wherein a total projected area of the second metallurgical bond is less than 90% of a total projected area of the substrate, and wherein a composition of the second metallurgical bond is a combination of a composition of the second substrate and a composition of the particles, a reaction product of the second substrate and the particles, or a combination thereof.

[0063] Examples

[0064] Comparative Example 1 : Bonding sputtered carbon on titanium

[0065] Commercially available grade 2 titanium foil was used as the substrate. A 50 nm Ti and 100 nm carbon (SP-C coating) was coated on the entire surface of the titanium foil by sputter deposition.

[0066] Example 1 : Bonding of milled carbon fibers on titanium foil

[0067] Commercially available grade 2 titanium foil was used as the substrate. Milled carbon fiber particles were loosely sprinkled on the surface and then heat treated at 900 °C for 1 hour in argon. The milled carbon fiber particles were 8 μm in diameter and 50 μm to 200 μm in length. The milled carbon fiber particles partially covered the titanium surface and could not be removed by ultrasonic cleaning, indicating that the carbon fibers were strongly bonded to the titanium.

[0068] Contact resistance

[0069] The contact resistance of the coated titanium foils of Comparative Example 1 and Example 1 was measured before and after the corrosion test, respectively, against AvCarb MGL 190 carbon paper. The accelerated corrosion test was performed at 80 °C and 1.4 V NHE An accelerated corrosion test was performed. The electrical contact resistance before and after the corrosion test was measured using AvCarb MGL 190 carbon paper at a compressive pressure of 200 PSI.

[0070] At 1.4 V NHE After 0.5 hours and 2 hours of the corrosion test, the surface contact resistance of Comparative Example 1 increased from the initial 4.0 mΩ.cm 2 to 28 mΩ.cm 2 and 333 mΩ.cm 2 respectively. After the corrosion test, the surface composition of Comparative Example 1 was analyzed using X-ray photoelectron spectroscopy (XPS). The XPS analysis found that the titanium surface was still covered with carbon, indicating that the carbon coating was not completely depleted during the corrosion test. Although not wishing to be bound by theory, it is believed that the high contact resistance is due to the interface between the carbon and the titanium substrate, more specifically, due to the oxidation of titanium creating titanium oxide under the carbon coating.

[0071] In contrast, after 1.5 hours and 6 hours of the corrosion test at 1.4 V NHE , the contact resistance of Example 1 increased from the initial 0.7 mΩ.cm 2 to 1.4 mΩ.cm 2 and 1.7 mΩ.cm 2 respectively. Optical microscopic observation found that most of the carbon fibers were still bonded on the titanium surface. The durability of the carbon fiber coating on the titanium is believed to be due to the metallurgical bond including titanium carbide.

[0072] Example 2: Bonding of graphite on titanium

[0073] To demonstrate the applicability of bipolar plates for fuel cells or electrolyzers, commercially pure titanium foil was chosen as a substrate for surface modification to achieve low surface electrical contact resistance. The titanium foil had a thickness of 0.1 mm. Graphite powder (Alfa Aesar #46304) with an average particle size of 7 μm to 11 μm was used as the particulate material.

[0074] The graphite particles were dispersed in an ethanol solution to make a slurry containing 20 weight percent (wt%) graphite (based on the total weight of the slurry). The slurry was coated on the titanium surface and dried, leaving the graphite particles on the surface. The titanium foil with the graphite particles was then heat treated in a vacuum chamber using a focused electron beam for surface heating. The graphite particles reacted with the titanium, forming a metallurgical bond between the graphite particles and the titanium foil, including titanium carbide.

[0075] After the bonding step, the titanium foil was cleaned in an ultrasonic bath to remove unbound graphite particles. The metallurgically bonded graphite particles remained on the titanium substrate surface. Figure 8 Shown is an SEM photo of the graphite particles bonded on the titanium foil surface.

[0076] Example 3: Bonding glassy carbon on titanium

[0077] Commercially pure titanium foil was used as the metal substrate. Titanium foil with a thickness of 0.1 mm was used as the substrate. Glassy carbon spherical powder (Alfa Aesar #3489) with a particle size of 10 μm to 20 μm was used as the particulate material. The glassy carbon powder was dispersed in an ethanol solution by ultrasonic dispersion. Then, polyvinyl butyral was added to the slurry as a binder. The carbon particle concentration in the slurry was 15 weight percent and the binder concentration was 2 weight percent, based on the total weight of the slurry.

[0078] The titanium plate was immersed in the carbon particle slurry to coat a thin layer of the slurry on the titanium surface. The coated titanium plate was then heat treated in vacuum at 800 °C for 1 hour to metallurgically bond the carbon particles to the titanium surface. After the heat treatment, the titanium plate was cleaned in an ultrasonic bath to remove unbound carbon particles. The bonded particles remained on the titanium plate surface. Figure 6 Shown is an SEM photo of the glassy carbon spherical particles metallurgically bonded on the titanium surface. Figure 7 Shown is a comparison of the electrical contact resistance of carbon paper (AvCarb MGL 190) and a titanium plate with carbon particles bonded on the surface (Ti w / C) and a titanium plate without carbon particles on the surface (Ti w / o C) at different compressive pressures. Figure 7 Shown is that the carbon particles reduced the electrical contact resistance of the titanium plate with carbon felt from 82 mΩ.cm 2 to 1.6 mΩ.cm 2 at a compressive pressure of 200 PSI.

[0079] Example 4: Bonding titanium-carbon composite on stainless steel

[0080] To demonstrate the applicability of the bipolar plate for a fuel cell or the applicability of the electrode for a zinc-bromine flow battery, a stainless steel mesh was used as a metal substrate. The center of the stainless steel mesh was punched to form a channel structure. Titanium powder was mixed with milled carbon fiber particles in ethanol, with polyvinyl butyral as a binder. The average particle size of the titanium powder was 2.2 pm, and the average fiber diameter of the milled carbon fiber was 8 pm, with a length of 50-200 pm. The volume ratio of titanium to carbon was 1 : 1, and the concentration of the particles in the slurry was 25 wt%, with the concentration of the binder being 5 wt%, both based on the total weight of the slurry.

[0081] The stainless steel mesh was immersed in the slurry to coat a layer of the slurry on the stainless steel mesh. After the slurry on the stainless steel mesh was dried, the stainless steel mesh was heat treated in a vacuum at 800 °C for 1 hour. The titanium particles and the carbon fiber particles were metallurgically bonded to the stainless steel mesh and to each other to form a porous metal-carbon composite plate. In the formed part, the mesh structure with the punched stainless steel mesh and the flow channels was retained.

[0082] Although not wishing to be bound by theory, it is understood that the stainless steel mesh can fix the titanium and carbon particles during the heat treatment, thereby limiting the shrinkage of the particles in a direction perpendicular to the surface of the substrate and minimizing the shrinkage in the in-plane direction. Figure 9 Shown is an SEM image of the coated stainless steel mesh. Figure 10 Shown is a magnified view showing the microstructure of the Ti particles and the milled carbon fiber particles coated on the stainless steel mesh.

[0083] Example 5: Bonding titanium on stainless steel

[0084] A 316L stainless steel foil was used as a metal substrate. The thickness of the stainless steel foil was 0.1 mm. Titanium powder with a particle size of 2.2 pm was used as a particulate material.

[0085] Ten grams of titanium powder was dispersed in 30 grams of ethanol by ultrasonic dispersion. Then, 20 grams of a 15 wt% polyvinyl butyral ethanol solution was added to the titanium powder slurry. The mixture was put on a roll mixer for 12 hours to mix the titanium powder and the polyvinyl butyral completely, thereby making a slurry. The slurry was coated on the stainless steel foil using an airbrush, and dried at 80 °C for 1 hour. The titanium particle coating on the stainless steel foil after drying was about 25 pm thick. The coated stainless steel foil was heat treated in a vacuum at 750 °C for 1 hour to metallurgically bond the titanium particles on the surface of the stainless steel foil. Then, the stainless steel plate was ultrasonically cleaned to remove any un-fixed titanium powder. The titanium powder formed a rough, porous structure on the surface of the stainless steel.

[0086] Example 6: Bonding graphite on porous titanium

[0087] A porous titanium felt was used as the metallic substrate. The titanium felt had a thickness of 250 pm and a porosity of 75%. Graphite powder (Alfa Aesar 46304) was used as the plurality of particulate material. The graphite powder was dispersed in an ethanol solution with polyvinyl butyral to make a stable slurry. The slurry contained 5 wt% graphite and 1 wt% polyvinyl butyral based on the total weight of the slurry. The titanium felt was then soaked in the slurry to have the titanium felt carry the graphite particles. After the slurry was dried, the graphite-carrying titanium felt was heat treated at 750 °C for 1 hour to metallurgically bond the graphite particles on the titanium felt. When this component is used as a flow battery electrode, the graphite particles will function as the electrode reaction sites. Since the graphite particles are metallurgically bonded on the titanium felt, there is no need for a platinum coating.

[0088] It will be understood that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements can be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present.

[0089] It will be understood that, although the terms "first," "second," "third," etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. As such, "a first element," "a first component," "a first region," "a first layer," or "a first section" discussed below could be termed a second element, a second component, a second region, a second layer, or a second section without departing from the teachings herein.

[0090] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, "a," "an," and "the" are intended to mean zero, one, or more than one of the item being described, and are not limited to a singular number, unless otherwise indicated. For example, "a" or "an" element or component is understood to mean one or more elements or components, unless otherwise indicated. "One or more" does not exclude that more than one unit of the same item can be present. For example, "a polymer" can mean one or more polymers. "Or" means "and / or." As used herein, the term "and / or" includes any and all combinations of one or more of the associated items. It will be further understood that the terms "comprises" and / or "comprising," or "includes" and / or "including" when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and / or groups thereof.

[0091] Spatially relative terms (such as "beneath," "below," "lower," "above," "upper," and the like) can be used herein for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the term "below" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0092] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0093] Embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and / or tolerances, are to be expected. Thus, embodiments described herein are not to be construed as being limited to the particular shapes illustrated herein but are to include deviations in shapes that result from, for example, manufacturing. For example, a region illustrated or described as flat can often have rough and / or nonlinear features. Moreover, illustrated sharp angles can be rounded. Thus, the regions illustrated in the figures are schematic and their shapes are not intended to illustrate the precise shape of a region but are intended to be an example of a region together with its function and / or its

[0094] The above examples are merely intended for the purpose of illustration and can by no means be interpreted as limiting. Although reference is made to various embodiments, the words used are words of description and illustration rather than limitation. Furthermore, although reference is made to specific devices, materials and embodiments, there is no limitation to the details disclosed herein. On the contrary, the embodiments extend to all functionally equivalent structures, methods and uses within the scope of the appended claims.

Claims

1. A component having improved surface contact resistance and reactivity, characterized in that, The component includes: a metal substrate; and a plurality of particles bonded to a surface of the metal substrate by a metallurgical bond; wherein the plurality of particles includes a metal, carbon, or a combination thereof; wherein the metallurgical bond is between the particles and the metal substrate; wherein a total projected area of the metallurgical bond is less than 90% of a total projected area of the substrate; and wherein a composition of the metallurgical bond is a combination of a composition of the metal substrate and a composition of the plurality of particles, a reaction product of the metal substrate and the plurality of particles, or a combination thereof; The plurality of particles bonded to the metal substrate forms a porous coating, the porous coating is a porous coating including the metallurgical bonded particles, the porous coating has an average pore size of 3 nm to 100 μm and a thickness in a range of 1 μm to 1 mm, the metallurgical bond of the plurality of particles to the metal substrate enables elimination of shrinkage in a plane of the substrate, limits shrinkage of the plurality of particles to a perpendicular direction, and by eliminating shrinkage in the plane, the porous coating is formed to conform to a shape and structure of the metal substrate without distortion.

2. The component of claim 1, wherein The metal substrate includes Ti, Nb, Ta, Ni, Cr, alloys thereof, stainless steel, or a combination thereof; and the metal particles include Ti metal, Nb metal, Ta metal, Ni metal, Cr metal, alloys of the foregoing metals, or a combination of the foregoing metals.

3. The component of claim 1, wherein The plurality of particles includes metal particles having an average particle size of 10 nm to 10 μm.

4. The component of claim 1, wherein The plurality of particles includes Ti particles having an average particle size of 100 nm to 5 μm.

5. The component of claim 1, wherein The plurality of particles includes carbon particles of amorphous carbon, graphite, carbon fibers, or a combination thereof, and the carbon particles have an average particle size of less than 200 μm.

6. The component of claim 1, wherein The metallurgical bond has a total projected area of 1% to 70% of a total projected area of the metal substrate.

7. The component of claim 1, wherein The component further includes a plurality of ceramic particles on the metal substrate, wherein the plurality of ceramic particles includes carbides, oxides, nitrides, silicides, or a combination thereof.

8. The component of claim 1, wherein The component is a bipolar plate for a fuel cell, a flow battery, or an electrolyzer, or is an electrode for an electrolyzer or a flow battery.

9. The component of claim 1, wherein The component includes a second substrate on a side of the plurality of particles opposite the metal substrate; wherein the second substrate includes carbon or Ti metal, Nb metal, Ta metal, Ni metal, Cr metal, alloys of the foregoing metals, or stainless steel; wherein the plurality of particles is bonded to the second substrate by a second metallurgical bond between the plurality of particles and the second substrate, wherein the second metallurgical bond has a projected area of less than 90% of a total projected area of the second substrate; and wherein the second metallurgical bond has a composition that is a combination of a composition of the second substrate and a composition of the plurality of particles, a reaction product of the second substrate and the plurality of particles, or a combination thereof.

10. The component of claim 9, wherein The second substrate is a metal separator having an open area of 10% to 90% by a total projected area of the second substrate, or is a porous mass transport layer having a porosity of 30% to 95%.

11. A method of manufacturing a component having improved surface contact resistance and reactivity, characterized by, The method includes: providing a metal substrate; depositing a mixture including a plurality of precursor particles on the metal substrate, wherein the plurality of precursor particles includes a metal, carbon, a metal hydride, or a combination thereof, to form a coated metal substrate; wherein a contact area of the plurality of precursor particles contacting the metal substrate is less than 90% of a total projected area of the substrate; and wherein an average particle size of the plurality of precursor particles is less than 200 μm; and heat treating the metal substrate having the plurality of precursor particles deposited thereon to form particles from the plurality of precursor particles and bond the particles to the metal substrate through a metallurgical bond formed between the particles and the metal substrate to produce the component; wherein a composition of the metallurgical bond is a combination of a metal substrate composition and a particle composition, a reaction product of the metal substrate and the particles, or a combination thereof; the plurality of particles bonded to the metal substrate forms a porous coating, the porous coating is a porous coating including metallurgically bonded particles, the porous coating has an average pore size ranging from 3 nm to 100 μm and a thickness ranging from 1 μm to 1 mm, the metallurgical bond of the plurality of particles to the metal substrate enables elimination of shrinkage in a planar direction of the substrate, limits shrinkage of the plurality of particles to a perpendicular direction, and by eliminating shrinkage in the planar direction, the porous coating is formed to conform to a shape and structure of the metal substrate without distortion.

12. The manufacturing method according to claim 11, wherein the metal substrate includes a Ti metal, a Nb metal, a Ta metal, an Al metal, a Ni metal, a Cr metal, an alloy of the foregoing metals, or a stainless steel.

13. The manufacturing method according to claim 11, wherein the plurality of precursor particles includes a Ti metal, a Nb metal, a Ta metal, an Al metal, a Cr metal, an alloy of the foregoing metals, an intermetallic compound of the foregoing metals, or a hydride of the foregoing metals, and has an average particle size ranging from 50 nm to 20 μm; or the plurality of precursor particles includes carbon particles having an average particle size less than 200 μm.

14. The method of manufacturing as defined in claim 11, wherein, the plurality of precursor particles covers 3% to 90% of a total projected area of the substrate.

15. The method of manufacturing as defined in claim 11, wherein the heat treatment includes a heat treatment performed in a vacuum or a non-oxidizing atmosphere, and wherein the heat treatment includes electron beam surface heating or laser surface heating.

16. The method of manufacturing as defined in claim 11, wherein the mixture includes a plurality of ceramic particles, wherein the ceramic particles include carbides, oxides, nitrides, or a combination thereof.

17. The method of manufacturing as defined in claim 11, wherein the component further includes placing a second substrate on a side of the plurality of precursor particles opposite the metal substrate, wherein the second substrate includes carbon or a Ti metal, a Nb metal, a Ta metal, a Ni metal, a Cr metal, an alloy of the foregoing metals, or a stainless steel, and wherein the particles are bonded to the second substrate through a second metallurgical bond between the particles and the second substrate, wherein a projected area of the second metallurgical bond is less than 90% of a total projected area of the second substrate, and wherein the second metallurgical bond has a composition that is a combination of a second substrate composition and a particle composition, a reaction product of the second substrate and the particles, or a combination thereof.

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