Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process
  • C23C30/005—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process on hard metal substrates
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/50—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on rare-earth compounds
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
  • C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
  • C23C10/30—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes using a layer of powder or paste on the surface
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
  • C23C14/08—Oxides
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C24/00—Coating starting from inorganic powder
  • C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
  • C04B2235/3224—Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
  • C04B2235/3229—Cerium oxides or oxide-forming salts thereof
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/60—Aspects relating to the preparation, properties or mechanical treatment of green bodies or pre-forms
  • C04B2235/604—Pressing at temperatures other than sintering temperatures

Definitions

• This invention relates generally to nonwetting materials and, more particularly, to hydrophobic materials that include rare earth elements.
• hydrophobic/superhydrophobic surfaces include creating a rough or textured surface and then modifying the surface by materials with low surface energies, such as polymers or
• hydrophobic materials that are resistant to high temperatures, harsh chemicals, and mechanical wear and tear (e.g., abrasion and impact).
• novel hydrophobic ceramics comprising rare earth oxides are described that demonstrate superior water repellency and promote dropwise water condensation. These ceramics surpass the state-of-the-art in the field of water repellency in their capability to repel water droplets even from smooth surfaces and their ability to promote dropwise condensation, with remarkably improved heat transfer coefficients. Because these novel ceramic surfaces are robust (i.e., capable of withstanding harsh environments), their deployment may enhance process efficiency, while reducing overall costs and energy consumption in a wide variety of applications that are negatively affected by droplet impingement and filmwise condensation. Examples include steam turbine blades, heat exchangers, condensers, and waterproof consumer products.
• hydrophobic The materials and coatings described herein are uniquely capable of repelling water droplets and offering mechanical resistance, chemical inactivity, thermal stability, ease of cleaning, and other advantages. Further, hydrophobic surfaces based on the materials described herein have the advantage of being more scalable and practical for industrial applications, compared to previous low surface energy organic materials that are physically and thermally unstable and fail under harsh environments.
• the articles and materials described herein may be used in a wide variety of industrial applications where hydrophobicity, droplet repellency, and/or dropwise condensation are desirable. These materials may also offer other industrial implications in development of anti- fouling and anti-icing surfaces. For example, these materials may be used in steam turbines, condensers, heat exchangers, aircraft, wind turbines, pipelines, evaporators, boilers, medical devices and implants, and separators.
• the invention relates to an article that includes a base substrate and a hydrophobic coating on the base substrate.
• the hydrophobic coating includes a rare earth element material.
• An exposed surface of the hydrophobic coating has a dynamic contact angle with water of at least about 90 degrees.
• the invention in another aspect, relates to an article containing a rare earth element material.
• An exposed surface of the article has a dynamic contact angle with water of at least about 90 degrees.
• the rare earth element material includes a rare earth oxide, a rare earth carbide, a rare earth nitride, a rare earth fluoride, and/or a rare earth boride.
• the rare earth element material includes a combination of one or more species within one or more of the following categories of compounds: a rare earth oxide, a rare earth carbide, a rare earth nitride, a rare earth fluoride, and a rare earth boride.
• the rare earth element material may include a combination of at least two members selected from the group consisting of a first rare earth oxide, a second rare earth oxide, a first rare earth carbide, a second rare earth carbide, a first rare earth nitride, a second rare earth nitride, a first rare earth fluoride, a second rare earth fluoride, a first rare earth boride, and a second rare earth boride.
• the rare earth element material may include a rare earth oxide.
• the article includes a metal and/or a ceramic.
• a thickness of the coating is preferably from about 100 nm to about 300 nm.
• the coating includes a ceramic, a metal, and/or a polymer.
• the coating may be doped with the rare earth element material.
• the exposed surface includes (or is) a textured surface (e.g., multiple-scale surface roughness).
• the rare earth element material includes a first rare earth oxide doped with a second rare earth oxide.
• the first rare earth oxide may be a light rare earth oxide
• the second rare earth oxide may be a heavy rare earth oxide.
• the heavy rare earth oxide may include, for example, gadolinium oxide (Gd 2 0 3 ), terbium oxide (Tb 4 0 7 ), dysprosium oxide (Dy 2 0 3 ), holmium oxide (Ho 2 0 3 ), erbium oxide (Er 2 0 3 ), thulium oxide (Tm 2 0 3 ), ytterbium oxide (Yb 2 0 3 ), and/or lutetium oxide (Lu 2 0 3 ).
• the light rare earth oxide is cerium oxide (Ce0 2 ) and the heavy rare earth oxide is gadolinium oxide (Gd 2 0 3 ).
• the rare earth element material includes scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and/or lutetium (Lu).
• the rare earth element material includes scandium oxide (SC 2 O 3 ), yttrium oxide (Y 2 O 3 ), lanthanum oxide (La 2 0 3 ), cerium oxide (Ce0 2 ), praseodymium oxide ( ⁇ 6 ⁇ ), neodymium oxide (Nd 2 0 3 ), samarium oxide (Sn ⁇ C ⁇ ), europium oxide (EU 2 O 3 ), gadolinium oxide (Gd 2 0 3 ), terbium oxide (Tb 4 0 7 ), dysprosium oxide (Dy 2 0 3 ), holmium oxide (H0 2 O 3 ), erbium oxide (E ⁇ C ⁇ ), thulium oxide (Tm 2 0 3 ), ytterbium oxide (Yb 2 0 3 ), and/or lutetium oxide (LU 2 O 3 ).
• SC 2 O 3 scandium oxide
• Y 2 O 3 yttrium oxide
• Y 2 O 3 lanthanum oxide
• the rare earth element material includes cerium carbide (CeC 2 ), praseodymium carbide (PrC 2 ), neodymium carbide (NdC 2 ), samarium carbide (SmC 2 ), europium carbide (EuC 2 ), gadolinium carbide (GdC 2 ), terbium carbide (TbC 2 ), dysprosium carbide (DyC 2 ), holmium carbide (HoC 2 ), erbium carbide (ErC 2 ), thulium carbide (TmC 2 ), ytterbium carbide (YbC 2 ), and/or lutetium carbide (LuC 2 ).
• the rare earth element material includes cerium nitride (CeN), praseodymium nitride (PrN), neodymium nitride
• NdN samarium nitride
• SmN europium nitride
• EuN europium nitride
• GdN gadolinium nitride
• TbN terbium nitride
• DyN dysprosium nitride
• HoN holmium nitride
• ErN erbium nitride
• TmN thulium nitride
• YbN ytterbium nitride
• LuN lutetium nitride
• the rare earth element material includes cerium fluoride (CeF 3 ), praseodymium fluoride (PrF 3 ), neodymium fluoride (NdF 3 ), samarium fluoride (SmF 3 ), europium fluoride (EUF 3 ), gadolinium fluoride (GdF 3 ), terbium fluoride (TbF 3 ), dysprosium fluoride (DyF 3 ), holmium fluoride (H0F 3 ), erbium fluoride (ErF 3 ), thulium fluoride (TmF 3 ), ytterbium fluoride (YbF 3 ), and/or lutetium fluoride (LuF 3 ).
• CeF 3 cerium fluoride
• PrF 3 praseodymium fluoride
• NdF 3 neodymium fluoride
• SmF 3 samarium fluoride
• EUF 3 europium
• the article is a steam turbine, a condenser, a heat exchanger, an aircraft, a wind turbine, a pipeline, an evaporator, a boiler, a medical device, a medical implant, and/or a separator.
• the invention in another aspect, relates to an article having a bulk material doped with a rare earth element material.
• An exposed surface of the bulk material or the article has a dynamic contact angle with water of at least about 90 degrees.
• the rare earth element material includes a rare earth oxide, a rare earth carbide, a rare earth nitride, a rare earth fluoride, and/or a rare earth boride.
• the bulk material may include a ceramic (e.g., a metal oxide, a metal carbide, and/or a metal nitride).
• the ceramic may include aluminum oxide, aluminum nitride, boron oxide, boron nitride, boron carbide, titanium oxide, titanium nitride, and/or titanium carbide.
• the bulk material is a light rare earth oxide doped with a heavy rare earth oxide.
• the bulk material is cerium oxide (Ce0 2 ) and the rare earth element material includes gadolinium oxide (Gd 2 0 3 ), terbium oxide (Tb 4 0 7 ), dysprosium oxide
• the rare earth element material includes scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and/or lutetium (Lu).
• the rare earth element material may include scandium oxide (SC 2 O 3 ), yttrium oxide (Y 2 O 3 ), lanthanum oxide (La 2 0 3 ), cerium oxide (Ce0 2 ), praseodymium oxide ( ⁇ ⁇ ⁇ ), neodymium oxide (Nd 2 0 3 ), samarium oxide (Sm 2 0 3 ), europium oxide ( ⁇ 3 ⁇ 4(3 ⁇ 4), gadolinium oxide (Gd 2 0 3 ), terbium oxide (Tb 4 0 7 ), dysprosium oxide (Dy 2 0 3 ), holmium oxide (H0 2 O 3 ), erbium oxide (E ⁇ C ⁇ ), thulium oxide
• the rare earth element material includes cerium carbide (CeC 2 ), praseodymium carbide (PrC 2 ), neodymium carbide (NdC 2 ), samarium carbide (SmC 2 ), europium carbide (EuC 2 ), gadolinium carbide (GdC 2 ), terbium carbide (TbC 2 ), dysprosium carbide (DyC 2 ), holmium carbide (HoC 2 ), erbium carbide (ErC 2 ), thulium carbide (TmC 2 ), ytterbium carbide (YbC 2 ), and/or lutetium carbide (LuC 2 ).
• CeC 2 cerium carbide
• PrC 2 praseodymium carbide
• NdC 2 neodymium carbide
• SmC 2 samarium carbide
• EuC 2 europium carbide
• GdC 2 gadolinium carbide
• the rare earth element material may include, for example, cerium nitride (CeN), praseodymium nitride (PrN), neodymium nitride (NdN), samarium nitride (SmN), europium nitride (EuN), gadolinium nitride (GdN), terbium nitride (TbN), dysprosium nitride (DyN), holmium nitride (HoN), erbium nitride (ErN), thulium nitride (TmN), ytterbium nitride (YbN), and/or lutetium nitride (LuN).
• CeN cerium nitride
• PrN praseodymium nitride
• NdN neodymium nitride
• SmN samarium nitrid
• the rare earth element material includes cerium fluoride (CeF 3 ), praseodymium fluoride (PrF 3 ), neodymium fluoride (NdF 3 ), samarium fluoride (SmF 3 ), europium fluoride (EuF 3 ), gadolinium fluoride (GdF 3 ), terbium fluoride (TbF 3 ), dysprosium fluoride (DyF 3 ), holmium fluoride (H0F 3 ), erbium fluoride (ErF 3 ), thulium fluoride (TmF 3 ), ytterbium fluoride (YbF 3 ), and/or lutetium fluoride (LUF 3 ).
• CeF 3 cerium fluoride
• PrF 3 praseodymium fluoride
• NdF 3 neodymium fluoride
• SmF 3 samarium fluoride
• EuF 3 europium
• the article is a steam turbine, a condenser, a heat exchanger, an aircraft, a wind turbine, a pipeline, an evaporator, a boiler, a medical device, a medical implant, and/or a separator.
• the bulk material contains at least about 10 weight percent rare earth element material, or at least about 25 weight percent rare earth element material.
• the invention in another aspect, relates to an article having carbon nanotubes and a hydrophobic coating on the carbon nanotubes.
• the hydrophobic coating includes a rare earth element material.
• An exposed surface of the hydrophobic coating has a dynamic contact angle with water of at least about 90 degrees.
• the rare earth element material includes a rare earth oxide, a rare earth carbide, a rare earth nitride, a rare earth fluoride, and/or a rare earth boride.
• the coating may be doped with the rare earth element material.
• the article may be, for example, a steam turbine, a condenser, a heat exchanger, an aircraft, a wind turbine, a pipeline, an evaporator, a boiler, a medical device, a medical implant, and/or a separator.
• the invention in another aspect, relates to a method of manufacturing a hydrophobic article.
• the method includes providing a ceramic material and a rare earth element material, and heating the ceramic material and the rare earth element material to a temperature of at least about 1600 °C.
• the method forms a hydrophobic coating having a dynamic contact angle with water of at least about 90 degrees.
• the rare earth element material includes a rare earth oxide, a rare earth carbide, a rare earth nitride, a rare earth fluoride, and a rare earth boride.
• the method may include adding a binder and/or a promoter to the ceramic material and the rare earth element material.
• the invention in another aspect, relates to a method of manufacturing a hydrophobic article.
• the method includes: providing a powder having a rare earth element material;
• the rare earth element material includes a rare earth oxide, a rare earth carbide, a rare earth nitride, a rare earth fluoride, and/or a rare earth boride.
• the invention in another aspect, relates to a method of manufacturing a hydrophobic article.
• the method includes providing a base substrate and forming a coating on the base substrate.
• the coating includes a rare earth element material.
• the rare earth element material includes a rare earth oxide, a rare earth carbide, a rare earth nitride, a rare earth fluoride, and/or a rare earth boride.
• the forming step may include, for example, sputtering and/or sintering.
• FIG. 1 is a schematic side view of a droplet resting on a surface during a static contact angle measurement, according to an illustrative embodiment of the invention.
• FIG. 2 is a schematic side view of a droplet on a sloped surface during a dynamic contact angle measurement, according to an illustrative embodiment of the invention.
• FIG. 3 is a schematic cross-sectional view of a hydrophobic material having a base substrate and a hydrophobic coating, according to an illustrative embodiment of the invention.
• FIG. 4 is a schematic cross-sectional view of a hydrophobic material having a base substrate and a hydrophobic coating, according to an illustrative embodiment of the invention.
• FIG. 5 is a schematic cross-sectional view of a hydrophobic material having a bulk material doped with a rare earth oxide, according to an illustrative embodiment of the invention.
• FIG. 6 is a schematic illustration of a method of forming a hydrophobic coating on carbon nanotubes, wherein the hydrophobic coating includes a rare earth oxide, according to an illustrative embodiment of the invention.
• FIG. 7 is a schematic side view of water molecules on a hydrophilic aluminum oxide surface, according to an illustrative embodiment of the invention.
• FIG. 8 is a schematic side view of water molecules on a hydrophobic rare earth oxide surface, according to an illustrative embodiment of the invention.
• FIG. 9 is a photograph of a water droplet on a hydrophilic alumina surface, according to an illustrative embodiment of the invention.
• FIG. 10 is a photograph of a water droplet on a hydrophilic silica surface, according to an illustrative embodiment of the invention.
• FIG. 11 is a photograph of a water droplet on smooth silicon modified with cerium oxide, according to an illustrative embodiment of the invention.
• FIG. 12 is a photograph of a water droplet on nanograss silicon posts modified with cerium oxide, according to an illustrative embodiment of the invention.
• FIG. 13 is a collection of photographs of sintered rare earth oxide ceramics, according to an illustrative embodiment of the invention.
• FIG. 14 is a plot of measured advancing contact angles of water on sintered ceramics and on hydrophilic alumina and silica, according to an illustrative embodiment of the invention.
• FIG. 15 is a plot of calculated total surface free energy and the polar and apolar components of surface free energy, for sintered rare earth oxide ceramics, according to an illustrative embodiment of the invention.
• FIG. 16 is a scanning electron microscope image of nanograss silicon post arrays, modified for superhydrophobicity with a thin layer of sputtered ceria, according to an illustrative embodiment of the invention.
• FIG. 18 includes sequential high-speed photographs of a droplet impinging a smooth hydrophobic silicon wafer modified with a thin film of a rare earth oxide, according to an illustrative embodiment of the invention.
• FIG. 19 includes sequential high-speed photographs of a droplet impinging a nanograss silicon posts modified with a thin layer of ceria, according to an illustrative embodiment of the invention.
• FIG. 20 is a photograph of filmwise water condensation on a smooth, hydrophilic silicon surface, according to an illustrative embodiment of the invention.
• FIG. 21 is a photograph of dropwise water condensation on a smooth, hydrophobic fluorosilanized silicon wafer, according to an illustrative embodiment of the invention.
• FIG. 22 is a photograph of dropwise water condensation on a smooth, hydrophobic film of cerium oxide on a silicon wafer, according to an illustrative embodiment of the invention.
• FIG. 23 is a photograph of dropwise water condensation on a smooth, hydrophobic film of erbium oxide on a silicon wafer, according to an illustrative embodiment of the invention.
• FIG. 24 is a plot of measured condensation heat flux values for a cerium oxide surface, an erbium oxide surface, a fluorosilanized silicon surface, and a silicon surface, according to an illustrative embodiment of the invention.
• FIG. 25 is a photograph of water droplets resting on a hydrophobic cerium oxide surface and a hydrophobic silicon surface, according to an illustrative embodiment of the invention.
• FIG. 26 is a photograph of a water droplet on a fluorosilanized surface after the surface had been exposed to 400 °C for two hours, according to an illustrative embodiment of the invention.
• FIG. 27 is a photograph of a water droplet on a cerium oxide surface after the surface had been exposed to 400 °C for two hours, according to an illustrative embodiment of the invention.
• compositions, mixtures, systems, devices, articles, methods, and processes of the claimed invention encompass variations and adaptations developed using information from the embodiments described herein. Adaptation and/or modification of the compositions, mixtures, systems, devices, methods, and processes described herein may be performed by those of ordinary skill in the relevant art.
• devices and systems are described as having, including, or comprising specific components, or where processes and methods are described as having, including, or comprising specific steps, it is contemplated that, additionally, there are devices and systems of the present invention that consist essentially of, or consist of, the recited components, and that there are processes and methods according to the present invention that consist essentially of, or consist of, the recited processing steps.
• devices, articles, mixtures, and compositions are described as having, including, or comprising specific compounds and/or materials, it is contemplated that, additionally, there are devices, articles, mixtures, and compositions of the present invention that consist essentially of, or consist of, the recited compounds and/or materials.
• a static contact angle ⁇ between a liquid and solid is defined as the angle formed by a liquid drop 12 on a solid surface 14 as measured between a tangent at the contact line, where the three phases - solid, liquid, and vapor - meet, and the horizontal.
• the term "contact angle” usually implies the static contact angle ⁇ since the liquid is merely resting on the solid without any movement.
• dynamic contact angle ⁇ d is a contact angle made by a moving liquid 16 on a solid surface 18.
• the dynamic contact angle ⁇ d may exist during either advancing or receding movement, as shown in FIG. 2.
• an intrinsically hydrophobic material i.e., a material having an intrinsic contact angle with water of at least 90 degrees
• exhibits superhydrophobic properties e.g., a static contact angle with water of at least 120 degrees and a contact angle hysteresis of less than 30 degrees
• a surface texture e.g., micro-scale or nano- scale.
• typically nano-scale surface textures e.g., pores and/or posts
• an intrinsic contact angle is a static contact angle formed between a liquid and a perfectly flat, ideal surface. This angle is typically measured with a goniometer.
• multiple-scale surface roughness is understood to mean physical surface features with two or more characteristic lengths that differ by at least a factor of ten.
• a surface having multiple-scale surface roughness may include nanoscale and microscale pores and/or protrusions.
• the multiple-scale surface roughness features are produced using mechanical abrasion, self-assembly (e.g., layer by layer assembly or electric field assisted assembly) of nanoparticles, growth or deposition of nanostructures (e.g., carbon nanotubes), and/or lithograpy.
• rare earth element material is understood to mean a material with at least one component that contains (or is) a rare earth element material.
• a rare earth element material may contain or be a compound with a rare earth element chemical symbol in its chemical formula.
• the rare earth element material includes any material having at least one rare earth element.
• the rare earth element may include, for example, scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and/or lutetium (Lu).
• the rare earth element material comprises an elemental form of one or more rare earth elements.
• the rare earth element material includes one or more rare earth compounds.
• the rare earth element material includes or consists of a rare earth oxide, a rare earth carbide, a rare earth nitride, a rare earth fluoride, and/or a rare earth boride.
• the rare earth oxide includes scandium oxide (SC 2 O 3 ), yttrium oxide (Y 2 0 3 ), lanthanum oxide (La 2 0 3 ), cerium oxide (Ce0 2 ), praseodymium oxide ( ⁇ 6 ⁇ ), neodymium oxide (Nd 2 0 3 ), samarium oxide (Sm 2 0 3 ), europium oxide (Eu 2 0 3 ), gadolinium oxide (Gd 2 0 3 ), terbium oxide (Tb 4 0 7 ), dysprosium oxide (Dy 2 0 3 ), holmium oxide (Ho 2 0 3 ), erbium oxide (Er 2 0 3 ), thulium oxide (Tm 2 ), scandium oxide (SC 2 O 3 ), y
• the rare earth carbide may include cerium carbide (CeC 2 ), praseodymium carbide (PrC 2 ), neodymium carbide (NdC 2 ), samarium carbide (SmC 2 ), europium carbide (EuC 2 ), gadolinium carbide (GdC 2 ), terbium carbide (TbC 2 ), dysprosium carbide (DyC 2 ), holmium carbide (HoC 2 ), erbium carbide (ErC 2 ), thulium carbide (TmC 2 ), ytterbium carbide (YbC 2 ), and/or lutetium carbide (LuC 2 ).
• CeC 2 cerium carbide
• PrC 2 praseodymium carbide
• NdC 2 neodymium carbide
• SmC 2 samarium carbide
• EuC 2 europium carbide
• GdC 2 gadolinium carbide
• Possible rare earth nitrides include cerium nitride (CeN), praseodymium nitride (PrN), neodymium nitride (NdN), samarium nitride (SmN), europium nitride (EuN), gadolinium nitride (GdN), terbium nitride (TbN), dysprosium nitride (DyN), holmium nitride (HoN), erbium nitride (ErN), thulium nitride (TmN), ytterbium nitride (YbN), and/or lutetium nitride (LuN).
• CeN cerium nitride
• PrN praseodymium nitride
• NdN neodymium nitride
• SmN samarium nitride
• rare earth fluorides include cerium fluoride (CeF 3 ), praseodymium fluoride (PrF 3 ), neodymium fluoride (NdF 3 ), samarium fluoride (SmF 3 ), europium fluoride (EuF 3 ), gadolinium fluoride (GdF 3 ), terbium fluoride (TbF 3 ), dysprosium fluoride (DyF 3 ), holmium fluoride (HoF 3 ), erbium fluoride (ErF 3 ), thulium fluoride (TmF 3 ), ytterbium fluoride (YbF 3 ), and/or lutetium fluoride (LuF 3 ).
• CeF 3 cerium fluoride
• PrF 3 praseodymium fluoride
• NdF 3 neodymium fluoride
• SmF 3 samarium fluoride
• EuF 3 europium
• the rare earth element material includes a light rare earth element having an atomic number less than or equal to 63 and/or a heavy rare earth element having an atomic number greater than 63.
• a light rare earth oxide may include scandium oxide (Sc 2 0 3 ), yttrium oxide (Y 2 0 3 ), lanthanum oxide (La 2 0 3 ), cerium oxide (Ce0 2 ), praseodymium oxide ( ⁇ ), neodymium oxide (Nd 2 0 3 ), samarium oxide (Sm 2 0 3 ), and/or europium oxide (Eu 2 0 3 ).
• a heavy rare earth oxide includes gadolinium oxide (Gd 2 0 3 ), terbium oxide (Tb 4 0 7 ), dysprosium oxide (Dy 2 0 3 ), holmium oxide (Ho 2 0 3 ), erbium oxide (Er 2 0 3 ), thulium oxide (Tm 2 0 3 ), ytterbium oxide (Yb 2 0 3 ), and/or lutetium oxide (Lu 2 0 3 ).
• the rare earth element material includes any possible combination of two or more rare earth element materials.
• the rare earth element material may include a first rare earth oxide, a first rare earth carbide, a first rare earth nitride, a first rare earth fluoride, and/or a first rare earth boride combined with a second rare earth oxide, a second rare earth carbide, a second rare earth nitride, a second rare earth fluoride, and/or a second rare earth boride.
• the rare earth element material may include two or more rare earth oxides, two or more rare earth carbides, two or more rare earth nitrides, two or more rare earth fluorides, and/or two or more rare earth borides.
• a chemical formula for the rare earth element material is R ⁇ X , where R represents one or more rare earth elements in any molar ratio, ⁇ represents oxygen, carbon, nitrogen, fluorine, boron, or combinations thereof, in any molar ratio, and x is a number of atoms in the material or compound. Depending on the composition of the rare earth element material, x may or may not be an integer.
• the hydrophobic material includes a rare earth element material combined with a non-rare earth element material (i.e., a material that does not include a rare earth element).
• a rare earth element material e.g., a rare earth oxide
• the rare earth element material may be combined with one or more metals or ceramics, including a metal oxide, a metal nitride, a metal carbide, a metal fluoride, and/or a metal boride.
• a hydrophobic material 300 includes a coating 302 and a base substrate 304.
• the coating 302 includes or consists of one or more rare earth element materials, such as one or more rare earth oxides.
• a thickness T of the coating may be, for example, from about 100 nm to about 300 nm.
• the base substrate 304 includes a metal, a ceramic, and/or a polymer.
• the base substrate 304 may include a metal and/or a transition metal and/or their alloys, e.g., aluminum, copper, titanium, and/or steel.
• the base substrate 304 may include, for example, a ceramic such as a metal oxide, a metal carbide, and/or a metal nitride.
• ceramic materials include aluminum oxide, aluminum nitride, boron oxide, boron nitride, boron carbide, titanium oxide, titanium nitride, and/or titanium carbide.
• a method of producing the hydrophobic material includes providing the base substrate 304 and applying the coating onto the base substrate 304 using, for example, sputtering, sintering, and/or spraying.
• an adhesion or bonding layer is disposed between the coating 302 and the base substrate 304. The bonding layer may provide improved adhesion between the coating 302 and the base substrate 304.
• the bonding or adhesion layer may include, for example, a metal, an intermetallic, an alloy, and/or a ceramic.
• a metal for example, a metal, an intermetallic, an alloy, and/or a ceramic.
• Specific examples include indium (In), titanium (Ti), titanium nitride (TiN), chromium nitride (CrN), nickel aluminide (e.g., NiAl), MCrAlY, platinum, nickel, and/or aluminum.
• a hydrophobic material 400 includes a coating 402 and a base substrate 404 that each contain a rare earth element material (e.g., a rare earth oxide), although the concentration of rare earth element material is higher in the coating 402 than in the base substrate 404.
• the coating 402 may include a weight percent of the rare earth element material that is about an order of magnitude greater than the weight percent of the rare earth element material in the base substrate 404.
• the weight percent of rare earth element material in the coating 402 is at least about 10 percent, at least about 25 percent, or at least about 50 percent.
• a thickness of the coating 402 may be, for example, from about 100 nm to about 500 nm.
• the base substrate 404 may include, for example, a ceramic, such as a metal oxide, a metal carbide, and/or a metal nitride.
• ceramics include aluminum oxide, aluminum nitride, boron oxide, boron nitride, boron carbide, titanium oxide, titanium nitride, and titanium carbide.
• a weight percentage of rare earth element material (e.g., rare earth oxide) in the base substrate 404 is less than about 1 percent, less than about 10 percent, or less than about 25 percent.
• a weight percentage of the rare earth element material in the base substrate 404 may be substantially uniform, or the weight percentage may be higher near the coating 402 than away from the coating 402.
• a method of forming the base substrate 404 and the coating 402 includes exposing the material components (e.g., the rare earth element material and a ceramic) to high temperatures (e.g., from about 1200 °C to about 1600 °C) in a furnace, under atmospheric pressures. Under these conditions, the molecules of the rare earth element material (e.g., a rare earth oxide) migrate toward the surface of the material and accumulate to form the coating 402. At the same time, the ceramic material moves away from the surface to form the base substrate 404.
• a binder or promoter e.g., polyvinyl alcohol and/or polystyrene
• a hydrophobic material 500 includes a bulk material 502 that is impregnated or doped with a rare earth element material, such as a rare earth oxide 504.
• the hydrophobic material 500 includes at least about 10 percent, at least about 25 percent, or at least about 50 percent rare earth element material, by weight.
• the weight percentage of rare earth element material in the hydrophobic material 500 may be from about 10 percent to about 25 percent, from about 25 percent to about 50 percent, from about 50 percent to about 75 percent, or from about 75 percent to about 99 percent.
• the bulk material 502 includes a metal, a ceramic, and/or a polymer.
• the bulk material 502 may include a metal and/or a transition metal and/or their alloys, e.g., aluminum, copper, titanium, and/or steel.
• the bulk material 502 may include, for example, a ceramic such as a metal oxide, a metal carbide, and/or a metal nitride. Examples of ceramic materials include aluminum oxide, aluminum nitride, boron oxide, boron nitride, boron carbide, titanium oxide, titanium nitride, and/or titanium carbide.
• the bulk material 502 is a coating.
• the bulk material 502 with the doped rare earth element material may be coated onto a ceramic, metallic, or polymeric substrate, such as a tube, a block, or a turbine blade.
• the rare earth element material e.g., a rare earth oxide
• the bulk material 502 is coated onto a ceramic, metallic, or polymeric substrate, such as a tube, a block, or a turbine blade.
• the rare earth element material may be dispersed within the bulk material 502 as small micro or nano-sized particles.
• the rare earth element material reacts with another compound (e.g., a ceramic compound) in the bulk material 502 to form a new compound.
• lanthanum oxide (La 2 0 3 ) may react with boron oxide (B 2 0 3 ) to form LaB0 4 .
• a hydrophobic material 600 includes carbon nanotubes 602 and a coating 604 having a rare earth element material (e.g., a rare earth oxide).
• a method 606 of producing the hydrophobic material 600 includes disposing a rare earth element material 608 (or a material doped with the rare earth element material) over the carbon nanotubes 602 and sintering the rare earth element material 608 onto the carbon nanotubes 602. The sintering may be performed in an alumina crucible and/or take place at a temperature from about 1200 °C to about 1600 °C.
• the coating 604 is produced by spraying or sputtering. Due to surface textures in the resulting hydrophobic material 600, the hydrophobic material 600 with the carbon nanotubes 602 may exhibit superhydrophobic qualities.
• a rare earth element material is formed by dry pressing a powder of the rare earth element material to form a pressed rare earth element material (e.g., a pressed rare earth oxide).
• the pressing may occur, for example, at a pressure between 30,000 and 50,000 tsi (tons/in ) (e.g., in a cylindrical steel press mold), without use of any binding agents or additives.
• the pressed rare earth element material may then be sintered (e.g., inside a tube furnace under argon environment).
• the sintering temperature may be based on the melting point of the rare earth element material.
• the sintering temperature may be from about 60 percent to about 80 percent of the melting point of the rare earth element material. In one embodiment, the sintering temperature is from about 1400 °C to about 1650 °C.
• an article that includes one or more of the hydrophobic materials described herein.
• the article may have any shape or size and may be used for any purpose.
• the article may be substantially flat (e.g., a block or a plate), curved (e.g., a sphere, a cylinder, or a tube), small (e.g., a medical device), or large (e.g., an airplane wing or a wind turbine blade).
• the article is used in an application where a robust hydrophobic surface is desired.
• the article may be, for example, a steam turbine, a condenser, a heat exchanger, an aircraft, a wind turbine, a pipeline (e.g., an oil or gas pipeline), an evaporator, a boiler, a medical device or implant, and/or a separator.
• a steam turbine e.g., a steam turbine, a condenser, a heat exchanger, an aircraft, a wind turbine, a pipeline (e.g., an oil or gas pipeline), an evaporator, a boiler, a medical device or implant, and/or a separator.
• hydrophobic materials described herein offer vast industrial implications for improving efficiency and reducing overall cost and energy consumption in various industrial applications where hydrophobicity, droplet repellency, and/or dropwise condensation are desirable.
• the hydrophobic materials also have applications as anti-fouling and anti-icing surfaces.
• hydrophobic materials described herein may be used by steam turbine manufacturers to achieve higher power outputs by reducing efficiency losses caused by water droplets, entrained in steam, impinging on turbine blades and forming liquid films.
• the hydrophobic materials described herein are used in aircraft and/or wind turbines.
• surface designs made using the hydrophobic materials may prevent liquid water film formation on aircraft wings and wind turbine blades, due to the superior water repellency attribute of these materials.
• the materials may prevent aircraft surfaces from freezing, thereby enhancing safety and improving aerodynamic performance.
• the hydrophobic surfaces also have applications in industries where scaling problems are encountered. Scaling is a persistent problem in various industrial processes, including oil and gas flow through pipelines, desalination, steam generation, and hydrometallurgy.
• articles that include these materials may be engineered to provide anti-fouling.
• Such designs not only reduce costs of chemical and thermal treatment for scale inhibition and removal, they also have implications for efficiency, lifetime enhancement, and process reliability improvement in the respective processes.
• the hydrophobic materials are used in deep sea oil and gas industries.
• the hydrophobic materials may be utilized to provide hydrate -phobic surfaces that prevent hydrate-formation. Such applications may enhance flow assurance and prevent catastrophic failures in deep-sea oil and gas operations.
• hydrophobic materials may also be used in evaporators and/or boilers.
• Evaporators and boilers are heat transfer devices that convert a fluid from a liquid phase to a vapor phase. Similar to condensers, large inefficiencies may occur at the fluid-surface interfaces, due to the formation of vapor films and associated heat transfer resistance.
• the hydrophobic materials are used to overcome the fundamental limitations of boiling. For example, these materials may be used in applications in which rare earth oxides act as boiling nucleation sites, thereby resulting in increased rewetting of the surface during boiling and prevention of vapor film formation.
• hydrophobic materials described herein also have applications in medical devices and/or implants.
• these materials may be used in joint replacement surgery or other types of surgery, tubing (e.g., catheters), dialysis, and any other medical application in which robust hydrophobic materials are desired.
• hydrophobic materials described herein also have applications in separation devices. In one embodiment, these materials are used to separate oil- water mixtures.
• Rare earth elements have a peculiar electronic configuration, characterized by the successive addition of electrons to the inner 4f orbitals across the lanthanides row. Because the deep-lying 4f electrons are well shielded from the chemical surrounding by eight electrons of the (5s 2 p 6 ) outer shell, they do not take part in chemical bonding. This unique electronic structure accounts for relatively low standard atomization enthalpy and ionization potential of the rare earths, a property which makes them highly active reducing elements with
• FIG. 7 A schematic demonstration of the orientation of a water molecule 700 next to an alumina hydrophilic surface 702 is presented in FIG. 7.
• Aluminum atoms 704 at the surface 702 are electron deficient, with six electrons in their three "sp hybrid" orbitals. Therefore, to achieve a full octet of electrons, the aluminum atoms 704 strive to accept a pair of electrons from the water molecules 700 next to the surface. Such a tendency forces the water molecules 700 at the surface 702 to be oriented in such a way that they have three hydrogen bond (HB) vectors pointing towards the surface. Two of these vectors are associated with electron pairs and the other is associated with one of the OH bonds. The fourth HB vector, which is associated with the other OH bond, is pointing preferentially outward from the surface 702 to the bulk.
• the depicted water molecule orientation is consistent with results of MD simulations for hydrophilic surfaces.
• rare earth element materials e.g., rare earth oxides
• metal atoms have a different chemistry than that of aluminum atoms.
• electrons are being added into the inner 4f orbitals, which are shielded by eight electrons of the (5s 2 p 6 ) outer shell. Therefore, contrary to aluminum atoms, the valance band of rare earth elements has a full octet of electrons, and the empty orbitals, if any, are not accessible to the surrounding environment. Accordingly, it is presently believed rare earth elements have no tendency to either accept or donate electron pairs when in contact with wetting liquids. As a result, unlike other oxide ceramics, rare earth oxides are herein found to be hydrophobic.
• water molecules 800 in contact with a surface 802 of a rare earth element material orientate themselves in such a way that they have one HB vector, associated with an OH bond, preferentially pointing toward the surface.
• the remaining three HB vectors preferentially point outward from the surface, thus forming hydrogen bonds with other water molecules in the bulk. Since the 4f orbitals 804 of rare earths are completely shielded by the octet electrons of the outer (5s 2 p 6 ) orbitals 806, they have no tendency to accept or donate pairs of electrons when in contact with water molecules.
• additional atoms 808 in the rare earth element material may include oxygen, carbon, nitrogen, fluorine, and/or boron, depending on whether the rare earth element material includes a rare earth oxide, a rare earth carbide, a rare earth nitride, a rare earth fluoride, and/or a rare earth boride, respectively.
• Hydrophobic surfaces were produced by forming a thin coating (between about 200 nm and 350 nm) of a ceramic material containing a rare earth oxide onto both smooth and textured substrates. Wetting measurements indicated that advancing water contact angles of these surfaces ranged from 115° for smooth to 160° for textured substrates. These contact angles are well beyond the water contact angles obtained with common metal oxides, such as alumina (AI 2 O 3 ) and silica (Si0 2 ), which have water contact angles of about 25-30° and about 15-20°, respectively.
• FIGS. 9 through 12 depict water droplets 900 resting on the alumina surface 902, the silica surface 1000, the smooth hydrophobic surface 1100, and the textured hydrophobic surface 1200.
• results from these experiments show the following: (1) the hydrophobic materials are capable of repelling water droplets even when they are deposited on smooth substrates; (2) the hydrophobic materials promote dropwise water condensation with remarkably improved heat transfer coefficients, when tested inside a condensation chamber under simulated industrial conditions; and (3) the nonwetting properties of the hydrophobic materials remained unchanged when the hydrophobic materials were heated to 400°C for two hours and then cooled down to room temperature.
• other hydrophobic surfaces such as a surface coated with flourosilane (FOS), a common hydrophobic surface modifier, did not retain the hydrophobic properties under these conditions.
• FOS flourosilane
• rare earth oxide powders were synthesized for all the rare earth elements across the lanthanides row, except for promethium oxide because of its radioactive properties.
• rare earth oxide powders were dry pressed at a pressure between 30,000 and 50,000 tsi (tons per square inch) in a cylindrical steel press mold, without use of any binding agents or additives. After pressing, the materials were sintered inside a tube furnace under an argon environment. The sintering temperature for each rare earth ceramic was different and estimated based on its melting point (i.e., between 60% and 80% of the melting point of each rare earth oxide). Accordingly, sintering temperatures were from about 1400 °C to about 1650°C in this work. Photographs of sintered ceramics 1300 are depicted in FIG. 13.
• the wetting properties and total surface free energies were quantified through systematic contact angle measurements on the materials using the following three liquids: diiodomethane (DIM), ethylene glycol (EG), and water. These three well-characterized liquids formed the basis of surface free energy calculations utilizing the van Oss-Good-Chaudhury approach. To determine the relationship between the surface polarity and the nonwetting properties of the rare earth oxides, the apolar and polar components of total surface free energy were assessed. The magnitude of the apolar surface free energy was calculated based on measured contact angle data of the apolar liquid, diiodomethane (DIM), and Lifshitz-van der Waals analysis.
• DIIM diiodomethane
• EG ethylene glycol
• water water
• the polar component was calculated using the contact angle data of polar liquids, i.e., water and ethylene glycol (EG), and simultaneously solving the modified Young equation. Calculation results revealed that the polar component of surface free energy for all the rare earth oxide materials was negligible. This suggests that the surface of these ceramic oxides, contrary to common hydrophilic oxides, have fewer Lewis acid and base sites. Furthermore, results showed no significant variations in the calculated surface free energy of the ceramics across the lanthanides row, which suggests that these ceramics have comparable wetting properties.
• polar liquids i.e., water and ethylene glycol (EG)
• the reason for such observation may be attributed to the unique electronic configuration of these materials.
• the chemical significance of electron addition into inner 4/orbitals that are shielded by overlying 5s 2 p 6 electrons may be so slight that it results in remarkable similarities between the rare earth oxide wetting materials.
• FIGS. 14 and 15 Measured contact angles and surface energies (i.e., calculated total surface free energy and calculated apolar and polar components) for the rare earth oxide materials are illustrated in FIGS. 14 and 15, respectively.
• the intrinsic water contact angle of all test substrates lies between 105° and 115°, which is well beyond the water contact angle of common metal oxides.
• alumina and silica have water contact angles of about 30° and 20°, respectively.
• the results in these figures show that the rare earth oxide materials are hydrophobic.
• silicon nanograss posts 1600 were arranged in square arrays with a width a of about 10 ⁇ , a height h of about 10 ⁇ , and a spacing b from about 5 ⁇ to about 30 ⁇ .
• posts were placed inside an inductively coupled plasma chamber with a controlled flow of etching gases (i.e., SF 6 /0 2 ).
• etching gases i.e., SF 6 /0 2 .
• the average width of the grass wires was about 100 nm with spacing of about 100 nm to about 200 nm.
• the nanograss posts 1600 were then modified for superhydrophobicity with a thin layer of a rare earth oxide through sputtering.
• Advancing and receding water contact angles were measured to be 160° and 155°, respectively.
• FIGS. 18 and 19 The dynamics of the impingement of water droplets 1800 on the ceria-coated smooth and nanograss post surfaces is depicted in the images of FIGS. 18 and 19, respectively.
• Water droplet impingement velocity was about 1.2 m/s for the ceria-coated smooth surface (FIG. 18) and about 1.6 m/s for the ceria-coated nanograss post surface (FIG. 19).
• the results show that both surfaces repelled the water droplets 1800 after impingement.
• the results were impressive in the sense that water repellency was observed even on smooth ceria-coated surfaces, indicating that this ceramic is intrinsically hydrophobic.
• ceria-coated nanograss silicon posts were capable of repulsing water droplets with relatively high impact velocities (e.g., about 3.7 m/s).
• hydrophobic test surfaces were fabricated by depositing a thin layer of a representative rare earth oxide on smooth silicon wafers.
• the rare earth oxides used for the experiment were cerium oxide and erbium oxide.
• water condensation experiments were also performed on a hydrophilic silicon wafer as well as a hydrophobic silicon wafer that was modified with a thin coating of
• FIGS. 20 through 23 Snapshot images of the dynamics of condensate formation and shedding from test substrates are shown in FIGS. 20 through 23.
• FIG. 20 in the case of a bare silicon substrate 2000, which is analogous to other hydrophilic surfaces, filmwise condensation was observed. Specifically, a continuous liquid film formed on the silicon substrate 2000, which led to a significant heat transfer resistance between the steam and the surface, and a subsequent decrease in the measured heat flux, as depicted in the plot of FIG. 24.
• FIGS. 21 through 23 contrary to the filmwise condensation properties of bare silicon, dropwise condensation was observed on a hydrophobic FOS-coated silicon surface 2100 (FIG. 21), a cerium oxide surface 2200 (FIG. 22), and an erbium oxide surface 2300 (FIG. 23).
• the rare earth oxide coatings outperformed the state-of-the-art fluorosilane (FOS), which is a common material for surface modifications.
• the higher heat flux obtained with the rare earth oxide coatings could result in considerably enhanced heat transfer rates in condensation applications.
• FIG. 25 includes a photograph of water droplets 2500 on a sintered cerium oxide surface 2502 and a fluorosilanized silicon surface 2504 before heating to 400 °C for 2 hours.
• 26 and 27 include photographs of water droplets 2500 on these surfaces 2502, 2504 after heating to 400 °C for 2 hours.
• the sintered rare earth oxide tablet was the only material to possess hydrophobic attributes after the test (i.e., after heating in the furnace). Because FOS is not thermally stable at such high temperature, the FOS sample showed hydrophilic behavior after the test. This experiment further demonstrates that rare earth oxide materials are not only intrinsically hydrophobic, but they are capable of withstanding harsh industrial environments.
• the rare earth oxides are intrinsically hydrophobic and robust.
• the rare earth oxides (or other rare earth element materials) are incorporated into other engineered materials and structures to achieve enhanced attributes. Examples include ceramics doped with rare earth oxides, metals doped with rare earths oxides, and polymer composites having rare earth oxides.
• doping a rare earth oxide with another rare earth oxide may result in improved properties.
• a light rare earth oxide e.g., ceria
• a heavy rare earth oxide e.g., gadolinium oxide.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Ceramic Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Structural Engineering (AREA)
• Physical Vapour Deposition (AREA)

Priority Applications (1)

Applications Claiming Priority (1)

Publications (1)

Family

ID=45953241

Family Applications (1)

Country Status (1)

Cited By (10)

Citations (3)

• 2012
  • 2012-03-23 WO PCT/US2012/030370 patent/WO2013141877A1/fr not_active Ceased

Patent Citations (3)

Non-Patent Citations (4)

Similar Documents

Legal Events