EP3044185A1 - Particules d'oxyde métallique - Google Patents

Particules d'oxyde métallique

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Publication number
EP3044185A1
EP3044185A1 EP14772045.2A EP14772045A EP3044185A1 EP 3044185 A1 EP3044185 A1 EP 3044185A1 EP 14772045 A EP14772045 A EP 14772045A EP 3044185 A1 EP3044185 A1 EP 3044185A1
Authority
EP
European Patent Office
Prior art keywords
particles
molded
mol percent
molded particles
composition
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP14772045.2A
Other languages
German (de)
English (en)
Inventor
Kathleen M. Humpal
Brant U. Kolb
Margaret M. Vogel-Martin
Mark J. Hendrickson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
3M Innovative Properties Co
Original Assignee
3M Innovative Properties Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US14/025,958 external-priority patent/US9878954B2/en
Application filed by 3M Innovative Properties Co filed Critical 3M Innovative Properties Co
Publication of EP3044185A1 publication Critical patent/EP3044185A1/fr
Withdrawn legal-status Critical Current

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    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/48—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on zirconium or hafnium oxides, zirconates, zircon or hafnates
    • C04B35/486—Fine ceramics
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    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
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    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
    • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
    • C04B35/632—Organic additives
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    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
    • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
    • C04B35/632—Organic additives
    • C04B35/634—Polymers
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    • 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
    • C04B2235/3217—Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
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    • 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
    • C04B2235/3225—Yttrium oxide or oxide-forming salts thereof
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    • 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
    • C04B2235/3227—Lanthanum oxide or oxide-forming salts thereof
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    • 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
    • C04B2235/3231—Refractory metal oxides, their mixed metal oxides, or oxide-forming salts thereof
    • C04B2235/3244—Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof
    • C04B2235/3246—Stabilised zirconias, e.g. YSZ or cerium stabilised zirconia
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    • 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
    • C04B2235/602—Making the green bodies or pre-forms by moulding
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
    • C04B2235/656—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes characterised by specific heating conditions during heat treatment
    • C04B2235/6562—Heating rate
    • C—CHEMISTRY; METALLURGY
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
    • C04B2235/656—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes characterised by specific heating conditions during heat treatment
    • C04B2235/6565—Cooling rate
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/94—Products characterised by their shape
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/95—Products characterised by their size, e.g. microceramics
    • C—CHEMISTRY; METALLURGY
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • C04B2235/963—Surface properties, e.g. surface roughness
    • C—CHEMISTRY; METALLURGY
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • C04B2235/963—Surface properties, e.g. surface roughness
    • C04B2235/9638—Tolerance; Dimensional accuracy
    • E—FIXED CONSTRUCTIONS
    • E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
    • E06B—FIXED OR MOVABLE CLOSURES FOR OPENINGS IN BUILDINGS, VEHICLES, FENCES OR LIKE ENCLOSURES IN GENERAL, e.g. DOORS, WINDOWS, BLINDS, GATES
    • E06B3/00—Window sashes, door leaves, or like elements for closing wall or like openings; Layout of fixed or moving closures, e.g. windows in wall or like openings; Features of rigidly-mounted outer frames relating to the mounting of wing frames
    • E06B3/66—Units comprising two or more parallel glass or like panes permanently secured together
    • E06B3/663—Elements for spacing panes
    • E06B3/66304—Discrete spacing elements, e.g. for evacuated glazing units

Definitions

  • compositions comprising a plurality of molded particles, methods of making, and articles comprising the same.
  • Metal oxide particles have been disclosed, for example, in WO 2013/055432 (Kolb). Such particles have large dimensions, and need to be tooled into appropriate shapes for some applications. Smaller molded particles have also been disclosed, for example, in US 8123828 (Culler); however, such smaller particles are highly fractured. Molded particles that are not highly fractured or cracked would be useful for some applications.
  • a composition can comprise at least a first plurality of molded particles, each molded particle of the first plurality of molded particles comprising at least 70 mol percent Zr0 2 , wherein the first plurality of molded particles are uniform in shape; each of the molded particles of the first plurality of molded particles has a largest dimension of no more than 1 centimeter (cm); and 80 percent or more of the molded particles of the first plurality of molded particles are free of cracks having a maximum dimension greater than 10 micrometers.
  • the composition can, in some cases, comprise other particles that are not part of the first plurality of molded particles.
  • Such other particles do not necessarily have the same Zr0 2 content, shape, size, or lack of cracks as the first plurality of molded particles.
  • Articles can comprise the composition.
  • a method of making a composition comprising at least a plurality of first molded particles can comprise adding one or more radically polymerizable surface modifiers to a sol, the sol comprising crystalline metal oxide particles having an average primary particle size no greater than 50 nanometers, wherein at least 70 mol percent of the crystalline metal oxide in the composition is Zr0 2 , placing the sol into one or more molds, polymerizing the one or more radically polymerizable surface modifiers to convert the sol into a cured intermediate, and heating the cured intermediate at one or more temperatures for one or more periods of time to calcine and sinter the cured intermediate to form a plurality of molded particles.
  • FIG. 1 is an exploded perspective view of a vacuum insulated glass unit
  • FIG. 2 is a side sectional view of a vacuum insulated glass unit
  • FIGS. 3A-3H are diagrams of exemplary molded particles
  • FIGS. 3I-K are diagrams of exemplary molded particles with functional coatings
  • FIG. 3L is a diagram illustrating a draft angle in a molded particle
  • FIG. 4 is a diagram illustrating mechanical orientation of molded particle in a mold
  • FIG. 5A is a side sectional view of molded particle shape
  • FIG. 5B is a side sectional view of a molded particle with roughness
  • FIG. 5C is a side sectional view of a molded particle with roughness and warp.
  • FIG. 6 is an SEM micrograph of a hexagonally shaped molded particle.
  • “Variation” when applied to a physical attribute, such as size or volume, of an element in a set of like elements means the difference in the size of the attribute in the one or more elements having a value for the attribute that is the farthest from the arithmetic mean value for that attribute among all elements of the set from the arithmetic mean value for that attribute among all elements of the set. Variation can be measured in units or as a percent.
  • the variation in height of these elements is 0.1 cm, i.e., the difference between the height of the elements having heights that are the farthest from the arithmetic mean of the height of all of the elements (i.e., elements A and C, respectively having heights of 1.1 cm and 0.9 cm) from the arithmetic mean of the height of all of the elements (i.e., one third of the sum of the heights of all three elements, or 1 cm).
  • the 0.1 cm variation can be considered a variation of 10 %.
  • Uniform in shape means that a set of reference items, such as a plurality of particles, have one or more of the following attributes: (a) the variation in volume among the set of reference items is no more than 10%, no more than 5%, or no more than 2%; (b) the variation in size of the one or more smallest dimensions (e.g., height, length, width, depth, etc.) of the set of reference items is no more than 10%, no more than 5%, or no more than 2%; or (c) the variation in size of the one or more largest dimensions (e.g., height, length, width, depth, etc.) of the set of reference items is no more than 10%, no more than 5%, or no more than 2%.
  • the variation in volume among the set of reference items is no more than 10%, no more than 5%, or no more than 2%
  • the variation in size of the one or more smallest dimensions e.g., height, length, width, depth, etc.
  • the variation in size of the one or more largest dimensions e.
  • a “crack” is a material segregation or partitioning having a size ratio of 5: 1 or greater, 6: 1 or greater, 7: 1 or greater, 8: 1 or greater, 9: 1 or greater, 10: 1 or greater, 12: 1 or greater, or 15: 1 or greater in any two dimensions.
  • a "sol” is a stable colloidal suspension of small solid particles in a continuous liquid medium.
  • a “primary particle” is an unaggregated and non-agglomerated particle.
  • Primary particle size is the diameter of the smallest sphere that could enclose the reference primary particle.
  • Weight percent solids is the percent by weight of solid material that remains after the removal of all liquids in a composition, such as water and organic solvents, based on the total weight of the composition.
  • Molded particles are particles having a size and shape that is determined by the size and shape of a mold, rather than by a tooling process that shapes the particles.
  • a composition can comprise at least a first plurality of molded particles.
  • the first plurality of molded particles can comprise at least 70 mol percent zirconia (ZrC ⁇ ).
  • the first plurality of molded particles can be uniform in shape and size. Quantitatively, the particles in the first plurality of molded particles be uniform in size when all of the plurality of molded particles have a variation in volume that is no more than 10%, no more than 5%, or no more than 2%.
  • the first plurality of molded particles can have any shape depending on the intended use. Shapes include a disk, a cone, a cylinder, or a polyhedron. An exemplary shape is pyramidal. Spherical shapes are possible; however in most cases the first plurality of molded particles is not spherical in shape.
  • the shape has one or more largest dimensions and one or more smallest dimensions.
  • the shape of each of the individual molded particles in the first plurality of molded particles can be essentially the same. Quantitatively, this can occur when the variation in the largest dimension is no more than 10%, no more than 5%, or no more 2%, when the variation in the smallest dimension is no more than 10%, no more than 5%, or no more than 2%, or both.
  • the one or more largest dimensions of each of the first plurality of molded particles can be no more than 1 cm (10 mm).
  • the one or more largest dimensions of each of the plurality of molded particles can be no more than 7.5 mm, no more than 5 mm, no more than 2.5 mm, no more than 1 mm, no more than 0.75 mm, no more than 0.5 mm, no more than 0.25 mm, no more than 0.01 mm, or no more than 0.05 mm.
  • the one or more largest dimensions of each of the plurality of molded particles can also be 0.05 mm or greater, such as 0.1 mm or greater, 0.25 mm or greater, 0.5 mm or greater, 0.75 mm or greater, 1 mm or greater, 2.5 mm or greater, 5 mm or greater, or 7.5 mm or greater.
  • the molded particles in the first plurality of molded particles are often polycrystalline, with at least
  • the first plurality of molded particles being free of cracks having a maximum dimension greater than 10 micrometers. In some cases, at least 85%, at least 90%, at least 95%, or at least 99% of the first plurality of molded particles are free of cracks.
  • the individual particles in the first plurality of molded particles can also be free of cracks having a maximum dimension greater than 9 micrometers, greater than 8 micrometers, greater than 7 micrometers, greater than 6 micrometers, greater than 5 micrometers, greater than 4 micrometers, greater than 3 micrometers, greater than 2 micrometers, or greater than 1 micrometer.
  • the Zr0 2 can be present in 70 to 100 mol percent, such as 70 mol percent or greater, 75 mol percent or greater, 80 mol percent or greater, 85 mol percent or greater, 90 mol percent or greater, 95 mol percent or greater, 97 mol percent or greater, or 99 mol percent or greater.
  • the ⁇ 0 2 can be present in 100 mol percent or less, 99 mol percent or less, 97 mol percent or less, 95 mol percent or less, 90 mol percent or less, 85 mol percent or less, 80 mol percent or less, or 75 mol percent or less.
  • the first plurality of molded particles can contain metal oxides other than zirconia.
  • Rare earth oxides are an example of such metal oxides. When rare earth oxides are included, they can be present in amounts of 1 mol percent or greater, 5 mol percent or greater 10 mol percent or greater, 15 mol percent or greater, 20 mol percent or greater, or 25 mol percent or greater. Rare earth oxides can also be present in 30 mol percent or less, 25 mol percent or less, 20 mol percent or less, 15 mol percent or less, 10 mol percent or less, or 5 mol percent or less. Some molded particles can comprise from 1 mol percent to 30 mol percent rare earth oxides. In this context, the mol percent of rare earth oxide is based on the total mols of metal oxide in the molded particles. Exemplary rare earth oxides include Y 2 O 3 and La 2 03.
  • Y 2 O 3 When Y 2 O 3 is used, it is often present from 1 mol percent to 15 mol percent, such as 1 mol percent or greater, 2 mol percent or greater, 3 mol percent or greater, 4 mol percent or greater, 5 mol percent or greater, 6 mol percent or greater, 7 mol percent or greater, 8 mol percent or greater, 9 mol percent or greater, 10 mol percent or greater, 1 1 mol percent or greater, 12 mol percent or greater, 13 mol percent or greater, or 14 mol percent or greater.
  • Y 2 O 3 can also be used in 15 mol percent or less, 14 mol percent or less, 13 mol percent or less, 12 mol percent or less, 1 1 mol percent or less, 10 mol percent or less, 9 mol percent or less, 8 mol percent or less, 7 mol percent or less, 6 mol percent or less, 5 mol percent or less, 4 mol percent or less, 3 mol percent or less, or 2 mol percent or less.
  • La 2 03 is used, it is often present from 1 mol percent to 5 mol percent, such as 1 mol percent or greater, 2 mol percent or greater, 3 mol percent or greater or 4 mol percent or greater.
  • La 2 03 can also be present in amounts of 5 mol percent or less, 4 mol percent or less, 3 mol percent or less, or 2 mol percent or less.
  • the first plurality of molded particles can further comprise AI 2 O 3 .
  • the first plurality of molded particles can comprise AI 2 O 3 in amounts of 0.05 mol percent or greater, 0.1 mol percent or greater, or 0.25 mol percent or greater.
  • the amount of AI 2 O 3 can also be 0.5 mol percent or less, 0.25 mol percent or less, or 0.1 mol percent or less.
  • the amount of AI 2 O 3 can be from 0.01 mol percent to 0.5 mol percent of the total amount of metal oxides in the first plurality of molded particles.
  • metal oxides that can be used in the first plurality of molded particles include one or more of Ce0 2 , Pr 2 0 3, Nd 2 0 3 , Pm 2 0 3 , Sm 2 0 3 , Eu 2 0 3 , Gd 2 0 3 , Tb 2 0 3 , Dy 2 0 3 , Ho 2 0 3 , Er 2 0 3 , Tm 2 0 3 , Yb 2 0 3 , Fe 2 0 3 , Mn0 2 , Co 2 0 3 , Cr 2 0 3 , NiO, CuO, Bi 2 0 3 , and Ga 2 0 3 .
  • One or more of these other metal oxides can be used in amounts of 1 mol percent or greater, 5 mol percent or greater, 10 mol percent or greater, 15 mol percent or greater, 20 mol percent or greater, or 25 mol percent or greater. One or more of these other metal oxides can also be present in 30 mol percent or less, 25 mol percent or less, 20 mol percent or less, 15 mol percent or less, 10 mol percent or less, or 5 mol percent or less.
  • One or more of the other metal oxides discussed herein can be used in the amounts discussed herein in order to change the physical properties of the molded particles.
  • Use of such other metal oxides including but not limited to the use of Y 2 0 3 , La 2 0 3 , or both, can affect the crystal structure of the Zr0 2 in the particles.
  • Zr0 2 can have several phases, including cubic, tetragonal, and monoclinic; it can also be present in more than one phase in the same particle.
  • the phase or phases in which Zr0 2 exists can relate to the heat treatment of the Zr0 2 .
  • the monoclinic phase is stable from ambient temperature to about 1 ,200° C
  • the tetragonal phase is stable from about 1,200° C to about 2,370° C
  • the cubic phase is stable above 2,370° C.
  • Sintering zirconia can require temperatures above 1,200° C. Therefore the monoclinic phase often transforms to the tetragonal phase during sintering, and then transforms back to the monoclinic phase upon subsequent cooling. These transformations can be accompanied by volume expansion, which can crack or fracture the metal oxide.
  • Addition of Y 2 0 3 , La 2 0 3 , or both, to the Zr0 2 can prevent the destructive transformation.
  • the use of 2 mol percent or more of Y 2 0 3 can allow the tetragonal phase to be maintained as a metastable phase during cooling.
  • the cubic phase that can form at sintering temperatures can be retained during cooling.
  • yttria a mixture of the tetragonal and cubic phases can be formed during sintering, and in many cases those phases can be retained during cooling. Under rapid cooling conditions the cubic phase may be distorted to form another tetragonal phase known as tetragonal prime.
  • La 2 0 3 , or both Y 2 0 3 and La 2 0 3 are used, the appropriate amount will depend on what other metal oxides, if any, are present as well as the desired properties of the final product.
  • the cubic and tetragonal phases provide particles with the greatest strength and toughness, it can be desirable to stabilize the Zr0 2 in one or both of those phases and minimize conversion to the monoclinic phase.
  • Addition of Y 2 0 3 , La 2 0 3 , or both in the amounts disclosed can stabilize the cubic and tetragonal phases of Zr0 2 in the molded particles, thereby increasing or maintaining the physical integrity, toughness, or both, of the plurality of particles.
  • Additional metal compounds can be used as coloring agents in order to impart coloration to the first plurality of molded particles.
  • Such coloring agents include one or more of Fe 2 0 3 , Mn0 2 , Co 2 0 3 , Cr 2 0 3 , NiO, CuO, Bi 2 0 3 , Ga 2 0 3 , Er 2 0 3 , Pr 2 0 3 , Eu 2 0 3 , Dy 2 0 3 , Sm 2 0 3 , V 2 0 5 , W 2 0 5 or Ce0 2 .
  • coloring agents are typically present in amounts of 10 ppm or greater, 100 ppm or greater, 500 ppm or greater, 1,000 ppm or greater, 2,500 ppm or greater, 5,000 ppm or greater, 10,000 ppm or greater,
  • coloring agents can also be present in amounts of 20,000 ppm or less, 17,500 ppm or less, 15,000 ppm or less, 12,500 ppm or less, 10,000 ppm or less, 7,500 ppm or less, 5,000 ppm or less, 2,500 ppm or less, 1,000 ppm or less, 500 ppm or less, 100 ppm or less, or 50 ppm or less, based on the total content of all of the metal oxides in the first plurality of molded particles.
  • one or more of the coloring agents discussed herein can be used in amounts ranging from 10 ppm to 20,000 ppm, based on the content of metal oxides.
  • the composition can include particles other than the first plurality of molded particles. Such particles need not have the same properties, such as Zr0 2 content, size, uniformity, or crack- free characteristics, as the first plurality of molded particles.
  • the composition can comprise, for example, a first plurality of molded particles as described herein and one or more additional particles that have Zr0 2 content of less than 70 mol percent.
  • the composition can comprise a first plurality of molded particles as described herein and one or more additional particles that have a largest dimension greater than 1 cm.
  • the one or more additional particles can include a second plurality of molded particles.
  • the second plurality of molded particles can have one or more of a different chemical composition, a different shape, a different volume, a different longest dimension, a different shortest dimension, and a different size than the first plurality of molded particles.
  • the composition can further include still other additional particles, which can be molded particles or other particles.
  • the composition can also include a third plurality of molded particles, a fourth plurality of molded particles, and so forth, wherein each further plurality of molded particles is different from the first plurality of molded particles.
  • the one or more additional particles can be molded, for example according to the processes discussed herein or according to some other process, although this is not required since one or more additional particles that are not molded can also be part of the composition.
  • the composition comprising at least a first plurality of molded particles can be made by any suitable process.
  • One such process involves adding one or more radically polymerizable surface modifiers to a sol, the sol comprising crystalline metal oxide particles having an average particle size no greater than 50 nanometers, such as no greater than 40 nanometers, no greater than 30 nanometers, or no greater than 25 nanometers, wherein at least 70 mol percent of the crystalline metal oxide in the composition is Zr0 2 .
  • the sol can be prepared by any suitable methods.
  • One such method involves the use of one or more hydrothermal reactors.
  • the sol can be prepared by hydrothermal treatment of a feedstock containing aqueous metal salts.
  • the aqueous metal salts can be in the form of a solution, a suspension, or a combination thereof wherein some of the salts are dissolved while others are suspended.
  • the aqueous metal salts can be soluble in water.
  • the feedstock containing the aqueous metal salts is often an aqueous medium.
  • the aqueous medium can be water or a mixture of water with other water soluble or water miscible solvents.
  • the other water soluble or water miscible solvents can increase the solubility of the aqueous metal salts, and can include one or more of acetone, 1 -methoxy-2- propanol, ethanol, isopropanol, ethylene glycol, ⁇ , ⁇ -dimethylacetamide, and N-methyl pyrrolidine, and the like.
  • these solvents are typically present in no more than 20% by weight relative to the total weight of the feedstock, such as no more than 15% by weight, no more than 10% by weight, or no more than 5% by weight, in all cases relative to the total weight of the feedstock.
  • the pH of the feedstock can be acidic.
  • the pH can be less than 6, less than 5, or even less than 4.
  • the pH of the feedstock is from 3 to 4.
  • the pH of the feedstock can be adjusted to appropriate levels by the addition of one or more acids or one or more bases.
  • the acids are mineral acids such as hydrochloric acid, nitric acid, or sulfuric acid; acetic acid can also be used.
  • the bases are alkali metal hydroxides, such as sodium hydroxide or potassium hydroxide; bicarbonate, carbonate, and organic bases such as alkali metal ethoxide can also be used.
  • the liquid feedstock can be deionized or treated by reverse osmosis prior to adding the desired metal salts and prior to adjusting the pH to the appropriate level.
  • Such deionization or reverse osmosis can minimize the amount of unwanted ions in the feedstock.
  • Common ions that are often unwanted include one or more of alkali metal ions and alkaline earth metal ions.
  • a majority of the dissolved salts in the feedstock are usually carboxylate salts, rather than halide salts, oxyhalide salts, nitrate salts, or oxynitrate salts.
  • Such carboxylate can favor the formation of molded particles having a cubic or tetragonal crystal structure rather than a monoclinic crystal structure.
  • Any carboxylate anion can be used as the anion in the carboxylate metal salt.
  • Common carboxylate anions can have no more than four carbon atoms.
  • Exemplary carboxylate anions include one or more of formate, acetate, propionate, and butyrate, or a combination thereof.
  • the carboxylate anions salts are often acetate anions.
  • the feedstock can further include, for example, the corresponding carboxylic acid of the carboxylate anion.
  • feedstocks prepared from acetate salts often contain acetic acid.
  • zirconium salt is zirconium acetate salt, which can be represented by the chemical formula ZrO((4_ n )/2 ) +(CH 3 COO-) n , where n is from 1 to 2.
  • n can depend on a variety of factors, such as the pH of the feedstock. Methods of making zirconium acetate are described, for example, in W. B. Blumenthal, "The Chemical Behavior of Zirconium,” pp. 31 1-338, D. Van Nostrand Company, Princeton, NJ (1958). Suitable aqueous solutions of zirconium acetate are commercially available, for example, from Magnesium Elektron, Inc., Flemington, NJ.
  • Such solutions can contain, for example, up to 17 weight percent zirconium, up to 18 weight percent zirconium, up to 20 weight percent zirconium, up to 22 weight percent, up to 24 weight percent, up to 26 weight percent, and up to 28 weight percent zirconium, based on the total weight of the solution.
  • carboxylate salts can also be carboxylate salts.
  • carboxylate salts are commercially available. Because these salts are typically used at much lower concentration levels than the zirconium salt, salts other than carboxylate salts can also be used. Typically, using anions other than carboxylate for such other metal salts has no deleterious effect on the process or final product.
  • the total amount of the various metal salts dissolved in the feedstock can be readily determined based on the total percent solids selected for the feedstock.
  • the relative amounts of the various salts can be calculated to provide the desired chemical composition of the plurality of molded particles.
  • the feedstock can contain 5 or more weight percent solids.
  • the weight percent solids can be 10 or more, 1 1 or more, 12 or more, 13 or more, 14 or more, or 15 or more.
  • the weight percent solids can be no more than 19, no more than 20, no more than 21, no more than 22, no more than 23, no more than 24, or no more than 25.
  • the weight percent solids can be in a range from 10 to 25, such as froml2 to 22, from 14 to 20, or from 15 to 19.
  • the various dissolved salts in the feedstock can undergo hydrolysis and condensation reactions to form the primary particles of the sol. These reactions can be accompanied by the release of an acidic byproduct.
  • the byproduct can be one or more carboxylic acids corresponding to the carboxylate anions used for the metal salts, plus any other carboxylate salts in the feedstock.
  • the zirconium salt is zirconium acetate, then acetic acid can be formed as a byproduct of the hydrothermal reaction.
  • the reactor can be a batch reactor or a continuous reactor.
  • the heating times are typically shorter and the temperatures are typically higher in a continuous hydrothermal reactor compared to a batch hydrothermal reactor.
  • the time of the hydrothermal treatments can be varied depending, for example, on the type of reactor, the temperature of the reactor, and the concentration of the feedstock.
  • the pressure in the reactor can be autogenous, wherein the vapor pressure of the reactor is the vapor pressure of the aqueous medium of the feedstock at the temperature of the reactor.
  • the pressure in the reactor can also be hydraulic, wherein the pressure is set by pumping a fluid against a restriction. For example, the pressure can be set to a desired level by adding an inert gas, such as nitrogen or argon, into the reactor.
  • Suitable batch hydrothermal reactors are available, for example, from Parr Instruments Co., Moline,
  • the temperature is often in a range from 160° C to 275° C, such as 160° C to 250° C, 170° C to 250° C, 175° C to 250° C, 200° C to 250° C, 175° C to 225° C, 180° C to 220° C, 180° C to 215° C, or 190° C to 210° C.
  • the temperature can be 160° C or greater, 170° C or greater, 180° C or greater, or 190° C or greater.
  • the temperature can also be 250° C or less, 220° C or less, 215° C or less, or 210° C or less.
  • the feedstock can be placed in the batch reactor at room temperature.
  • the feedstock within the batch reactor can then be heated to an appropriate temperature, such as those discussed above, and held at that temperature for at least 30 minutes, for example, at least 1 hour, at least 2 hours, or at least 4 hours.
  • the temperature can be maintained for up to 24 hours, for example, up to 20 hours, up to 16 hours, or up to 8 hours. In some cases, an appropriate temperature can be maintained from 0.5 to 24 hours, such as from 1 to 18 hours, 1 to 12 hours, or 1 to 8 hours.
  • the size of the batch reactor can be selected depending on the amount of sol that is to be produced in each batch. For example, the volume of the batch reactor can be in a range from several milliliters to several liters or more.
  • Exemplary volumes are 2 mL or more, 5 mL or more, 10 mL or more, 25 mL or more, 50 mL or more, 100 mL or more, 250 mL or more 500 mL or more, 750 mL or more, 1 L or more, 2 L or more, 5 L or more, 10 L or more, 25 L or more, or 50 L or more.
  • Exemplary volumes can be 100 L or less, 50 L or less, 25 L or less, 10 L or less, 5 L or less, 2 L or less, 1 L or less, 750 mL or less, 500 mL or less, 250 mL or less, 100 mL or less, 50 mL or less, 25 mL or less, 10 mL or less, or 5 mL or less.
  • the feedstock can be passed through a continuous hydrothermal reactor.
  • the feedstock is continuously introduced and an effluent continuously removed from a heated zone of the reactor.
  • the introduction of feedstock and the removal of the effluent typically occur at different locations of the reactor.
  • the continuous introduction and removal can be constant or pulsed.
  • the temperature and the residence time (i.e., the average time that the feedstock is within a heated portion of the continuous hydrothermal reactor) in the reactor are typically selected so that the particular reactor will convert at least 90 mole percent of the metal salts, such as zirconium acetate, in the feedstock into particles after a single pass through the continuous hydrothermal reactor.
  • the reactor temperature in continuous hydrothermal reactors can be from 170° C to 275° C, 170° C to 250° C, 170° C to 225° C, 180° C to 225° C, 190° C to 225° C, 200° C to 225° C, or 200° C to 220° C.
  • the temperature can be 170° C or greater, 180 ° C or greater, 190 ° C or greater, or 200 " C or greater.
  • the temperature can also be 250 " C or less, 225 “ C or less, 220 “ C or less, or 200 " C or less.
  • temperatures above 275°C can result in pressures that are too high for the continuous hydrothermal reactor to function properly.
  • temperatures lower than 170°C can require unacceptably long residence times to give adequate conversion of the zirconium in the feedstock.
  • the feedstock is passed through a heated portion of the continuous hydrothermal reactor more than once.
  • the feedstock can be subjected to a first hydrothermal treatment to form a zirconium-containing intermediate and a byproduct such as a carboxylic acid.
  • a second feedstock can be formed by removing at least a portion of the byproduct of the first hydrothermal treatment from the zirconium-containing intermediate.
  • the second feedstock can then be subjected to a second hydrothermal treatment to form the sol containing the metal oxide particles.
  • Such processes are described, for example, in U.S. Pat. No. 7,241,437 (Davidson)
  • the percent conversion of the zirconium-containing intermediate can be from 40 to 75 mol percent.
  • the conditions, such as temperature, pressure, and residence time, used in the first hydrothermal treatment can be adjusted to provide conversion within this range. Any suitable methods, such as one or more of vaporization, dialysis, ion exchange, precipitation, and filtration, can be used to remove at least part of the byproduct of the first hydrothermal treatment.
  • the product obtained from the hydrothermal reactor is typically a sol.
  • the sol can contain metal oxide particles in the aqueous medium.
  • the particles can contain 70 mol percent or more of ZrC>2.
  • the particles in the sol can also contain one or more additional metal oxides, such as those discussed above.
  • the particles can be crystalline and can have an average primary particle size no greater than 50 nanometers.
  • the sol can be concentrated to increase the percent solids. Concentrating the sol can involve removing less than all of the aqueous medium. Any suitable method for removing the aqueous medium can be used. For example, part of the aqueous medium can be vaporized at ambient temperature, under mild heating (i.e., heating that does not affect the composition, crystal structure, or properties of the particles in the sol), under reduced pressure, or a combination thereof.
  • the aqueous medium can also contain dissolved carboxylic acids and salts thereof that are present in the feedstock or that are byproducts of the reactions that occur within the hydrothermal reactor. At least some of these dissolved carboxylic acids and salts thereof can be removed by any suitable method. Suitable methods include diafiltration and dialysis.
  • a sample of the sol can be placed within a membrane bag, the porosity of which is chosen such that the carboxylic acids and salts thereof can pass through the membrane but the metal oxide particles cannot pass through the membrane.
  • the membrane bag can be closed and placed within a water bath.
  • the carboxylic acid and salts thereof are allowed to diffuse out of the membrane bag.
  • the water in the bath can be replaced several times to promote diffusion of the carboxylic acids and salts thereof out of the membrane bag and into the water bath.
  • the sol can be filtered through a membrane that is permeable to the carboxylic acids and salts thereof but impermeable to the metal oxide particles.
  • the metal oxide particles can be retained on the membrane.
  • the sample can be diluted to a pre-determined volume and then concentrated to a desired volume by ultrafiltration. The dilution and concentration steps are repeated until the amount of carboxylic acid and salts thereof is reduced to an acceptable concentration level.
  • fresh water such as reverse osmosis water or deinonized water, is added at the same rate that aqueous medium is removed through filtration.
  • the dissolved carboxylic acid or salts thereof are in the aqueous medium that is removed.
  • the relative amounts of the various metal oxides in the sol can change upon diafiltration or dialysis. For example, dialysis of a sol produced with a Zr0 2 :Y 2 0 3 :La 2 0 3 molar ratio of 95.7:2.3:2 resulted in a sol with a Zr0 2 :Y 2 0 3 :La 2 0 3 molar ratio of 96.5:2.2: 1.3.
  • dialysis of a sol produced with a Zr0 2 :Y 2 0 3 molar ratio of 88: 12 resulted in a sol with a Zr0 2 :Y 2 0 3 molar ratio of 90.7:9.3.
  • the change in content of other compositions in the form of a sol upon dialysis or diafiltration can be calculated from these data using rule of mixtures.
  • One or more radically polymerizable surface modifiers can be added to the sol.
  • the one or more radically polymerizable surface modifiers are typically added after any concentration step, such as diafiltration or dialysis, to ensure that the one or more radically polymerizable surface modifiers are not removed during the concentration step.
  • Suitable radically polymerizable surface modifiers include ethylenically unsaturated surface modifiers.
  • ethylenically unsaturated surface modifiers can include ethylenically unsaturated acids, reaction products of alcoholic polymerizable monomers with cyclic anhydrides, and ethylenically unsaturated organosilanes.
  • acrylic acid methacrylic acid, beta-carboxyethyl acrylate, 2-(methacryloxyethyl)succinate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxyproyl methacrylate, hydroxylbutyl acrylate, hydroxybutyl methacrylate, alkyltrialkoxysilanes methacryloxyalkyltrialkoxysilanes, acryloxyalkyltrialkoxysilanes such as 3- methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, and 3- (methacryloxy)propyltriethoxysilane, 3 -(methacryloxy)propylmethyldimethoxysilane, 3 - (acryloxypropyl)methyldimethoxysilane), methacryloxyalkyldialkylalkoxysilanes,
  • acyrloxyalkyldialkylalkoxysilanes such as 3-(methacryloxy)propyldimethylethoxysilane
  • mercaptoalkyltrialkoxylsilanes such as 3-mercaptopropyltrimethoxysilane
  • aryltrialkoxysilanes such as styrylethyltrimethoxysilane
  • vinylsilanes such as vinylmethyldiacetoxysilane
  • Additional radically polymerizable compounds that do not modify the surface of the particles in the sol can also be added.
  • examples include monomers, such as (meth) acrylate monomers, styrenyl monomers, and epoxy monomers, as well as polymers and oligomers such as oligo- or polyesters having (meth)acrylate groups, oligo- or polyurethanes having (meth)acrylate groups, oligo- or polyethers having (meth)acrylate groups, and oligo- or polyacrylics.
  • the step of adding the one or more radically polymerizable surface modifiers can also include adding one or more radical initiators.
  • Suitable radical initiators include azobisisobututyronitrile, 2,2'- azodi-(2,4-dimethylvaleronitrile), l, l '-azobis(cyclohexanecabonitrile), benzoyl peroxide and lauryl peroxide.
  • UV active radical initiators are often used.
  • Such initiators include acetophenones, benzophenones, and thioxanthones.
  • the sol can then be placed into one or more molds.
  • Each of the one or more molds can have at least one cavity; in most cases, each of the one or more molds has a plurality of cavities.
  • the plurality of cavities in a mold can be formed in a belt, sheet, continuous web, or die, containing the one or more cavities. Use of one of the above-mentioned forms for the mold can be useful when the mold is to be used in a continuous process of forming molded particles.
  • the one or more molds can comprise one or more polymeric materials. Any suitable polymeric materials can be used.
  • the polymeric material can be one or more of polyester,
  • the entire one or more molds are made from one or more polymeric materials.
  • one or more surfaces of the one or more molds can have a coating of a polymeric material.
  • the one or more molds can be replicated from a master tool.
  • a master tool can have a pattern that is the inverse of the pattern that is on the mold in that the master tool can have protrusions that correspond to the cavities on the mold.
  • the master tool can be made of metal, such as nickel or an alloy thereof.
  • a polymeric sheet can be heated and placed next to the master tool. The polymeric sheet can then be pushed against the master tool to emboss the polymeric sheet, thereby forming a mold. It is also possible to extrude or cast one or more polymeric materials onto a master tool in order to produce the one or more molds. Many other types of mold materials, such as metal, can be embossed by a master tool in a similar manner.
  • Disclosures related to forming molds from master tools include U.S. Patents 5, 125,917 (Pieper), 5,435,816 (Spurgeon), 5,672,097 (Hoopman), 5,946,991 (Hoopman), 5,975,987 (Hoopman), and 6, 129,540 (Hoopman).
  • the one or more cavities in the mold can be any desired three-dimensional shape. Exemplary shapes include disks, cones, cylinders, and polyhedrons. Each mold often has a plurality of uniform cavities having the same size and shape. In some cases, each mold can have a plurality of first uniform cavities having a first size and a first shape and a plurality of second uniform cavities having a second size and a second shape, wherein one or both of the second size and second shape can be different from one or both of the first size and first shape. Further pluralities of cavities can also be present on the one or more molds, and can have further different sizes and shapes.
  • Use of one or more molds having more than one plurality of cavities, the more than one plurality of cavities each having a different size, shape, or both, can provide more than one plurality of molded particles, each plurality of molded particles having a different size, shape, or both.
  • the one or more molds have a plurality of first uniform cavities having a triangular shape and of second uniform cavities having a disk shape
  • the resulting composition will have a first plurality of molded particles having a triangular shape and a second plurality of molded particles having a disk shape.
  • the first plurality of molded particles are not in the shape of teeth.
  • the one or more cavities can each have one or more largest dimensions of that is no more than 1 cm (10 mm), such as no more than 7.5 mm, no more than 5 mm, no more than 2.5 mm, no more than 1 mm, no more than 0.75 mm, no more than 0.5 mm, no more than 0.25 mm, no more than 0.01 mm, or no more than 0.05 mm.
  • the one or more largest dimensions of each of the one or more cavities can also be 0.05 mm or greater, such as 0.1 mm or greater, 0.25 mm or greater, 0.5 mm or greater, 0.75 mm or greater, 1 mm or greater, 2.5 mm or greater, 5 mm or greater, or 7.5 mm or greater.
  • the one or more cavities can be free of release agents. This can be beneficial because it can help ensure that the contents of the mold stick to the mold walls and maintain the shape of the mold.
  • release agents can be applied to the surfaces of the cavities to ensure clean release of the molded particles from the mold.
  • the one or more cavities can be filled with the sol.
  • the sol can placed into the one or more cavities by any suitable methods. Examples of suitable methods include pumping through a hose, use of a knife roll coater, or use of a die such as a vacuum slot die.
  • a scraper or leveler bar can be used to force the sol into the one or more cavities, and to remove any of the sol that does not fit into the one or more cavities. Any portion of sol that does not fit into the one or more cavities can be recycled and used again later, if desired.
  • Dissolved oxygen can be removed from the sol, either before the sol is placed in the one or more molds or while the sol is in the one or more molds. This can be achieved by vacuum degassing or sparging with an inert gas such as nitrogen or argon. Removing dissolved oxygen can reduce the instance of unwanted side reactions, particularly unwanted reactions that involve oxygen. Because such side reactions are not necessarily detrimental to the product, and do not occur in all circumstances, removing dissolved oxygen is not required.
  • the sol can be cured by polymerizing the radically polymerizable surface modifiers and, if they are used, the additional radically polymerizable compounds. This curing can be carried out by any curing method.
  • One exemplary curing method is heat curing, whereby the sol is heated to a temperature sufficient to initiate a radical reaction.
  • a heat- activated radical initiator is used, this temperature is often from 60° C to 100° C.
  • curing can be carried out by exposing the sol to actinic radiation.
  • the actinic radiation is often in a wavelength where an added photoinitiator has a strong absorbance. Such wavelengths can include, for example, visible, ultraviolet, and the like.
  • Curing changes the sol to a cured intermediate.
  • the cured intermediate is often in the form of a gel.
  • the cured intermediate contains a solid or semi-solid matrix with liquid entrapped therein.
  • the liquid in the cured intermediate is often mostly water.
  • the water can be exchanged with a second liquid to remove some of the water.
  • this exchange is known as alcohol exchange.
  • Alcohol exchange can be accomplished by soaking the gel in a dry alcohol, that is, an alcohol with no dissolved water.
  • An exemplary dry alcohol is 200 proof ethanol. Removing water by alcohol exchange can be useful because many alcohols, such as ethanol and methanol, are more volatile than water and therefore easier to remove from the gel.
  • the cured intermediate can be dried. Drying can cause the cured intermediate to take the form of one or more aerogels or one or more xerogels. Drying can comprise removing solvent from the cured intermediate without excessively shrinking the cured intermediate.
  • the cured intermediate can lose no more than 30% of its volume, such as no more than 25% of its volume, no more than 20% of its volume, no more than 15% of its volume, no more than 10% of its volume, no more than 9% of its volume, no more than 8% of its volume, no more than 7% of its volume, no more than 6% of its volume, no more than 5% of its volume, no more than 4% of its volume, no more than 3% of its volume, no more than 2% of its volume, or no more than 1% of its volume upon drying.
  • the drying can be accomplished by any suitable means.
  • the solvent in the cured intermediate is allowed to evaporate at ambient temperature. Drying can also be accomplished at elevated temperatures, which can be no more than 200° C, no more than 175° C, no more than 150° C, or no more than 125° C. Elevated drying temperatures can be 25° C or greater, such as 30° C or greater, 50° C or greater, 75° C or greater, 100° C or greater, 125° C or greater, or 150° C or greater. In other cases, the solvent can be removed by supercritical extraction.
  • a supercritical fluid such as supercritical carbon dioxide
  • solvents such as alcohols, for example, ethanol
  • the metal oxide particles and polymerized surface modifiers, as well as the polymerized additional polymerizable compounds, if used, are typically not soluble in the supercritical fluid and therefore are not removed.
  • Supercritical extraction is discussed in detail in van Bommel, M.J., and de Haan, A.B. J. Materials Sci. 29 (1994) 943-948, Francis, A.W. J. Phys. Chem. 58 (1954) 1099- 1 1 14 and McHugh, M.A., and Krukonis, V.J. Supercritical Fluid Extraction: Principles and Practice. Stoneham, MA, Butterworth-Heinemann, 1986.
  • the cured intermediate contains the metals used in the feedstock in the form of metal oxides, as well as polymerized or cured versions of the radically polymerizable surface modifiers and, if used, polymerized or cured versions of the additional radically polymerizable compounds.
  • the organic content of the cured intermediate after drying is typically 3% or greater, such as 4% or greater, 5% or greater, 6 % or greater, 10% or greater, 15% or greater, 20% or greater, or 25% or greater.
  • the organic content of the cured intermediate after drying is often no more than 30%, such as no more than 25%, no more than 20%, no more than 15%, no more than 10%, or no more than 5%.
  • the cured intermediate can be calcined and sintered to form the plurality of molded particles.
  • Calcining and sintering can be accomplished by heating the cured intermediate to at least one temperature for at least one time. Calcining, which can occur first, can involve removal of any organic compounds from the metal oxides. Calcining can entail heating at a rate of 1° C per hour to 600° C, such as 5° C or more, 10° C per hour or more, 50° C per hour or more, 100° C or more, 200° C per hour or more, 300° C or more, 400° C or more, or 500° C or more.
  • the heating rate can also be 600° C per hour or less, 500° C per hour or less, 400° C per hour less, 300° C per hour less, 200° C per hour less, 100° C per hour less, 50° C per hour less, or 20° C per hour less.
  • the temperature increase can be stopped once a temperature of 600° C is reached. This heating profile can allow organic compounds to vaporize without causing cracks.
  • the temperature can be maintained at 600° C until organic compound removal is complete. Removal of organic compounds can be tracked by thermogravimetic analysis. Organic compound removal can be complete when only incidental loss of mass is detected by thermogravimetric analysis.
  • organic compound removal can be complete.
  • Incidental mass change can be a mass loss of, for example, less than 1%, less than 0.5%, less than 0.25%, less than 0.1%, less than 0.075%, less than 0.05%, less than 0.025%, less than 0.01%, less than 0.0075%, less than 0.005%, less than 0.0025%, or less than 0.001% after holding the organic compound at high temperature for the time period.
  • organic compound removal is not complete after the calcining step. In such cases, additional organic compounds can be removed during the sintering step, if needed.
  • Sintering can take place after the organic compounds are partially or completely removed.
  • the rate of temperature increase can be faster once the organic compounds are no longer present, because there is no longer any concern that vaporized organic compounds will cause cracks.
  • the temperature can be increased at a rate of 100° C per hour to 600° C per hour, until a temperature of 800° C to 1,350° C is reached.
  • This temperature can be maintained for sufficient time to sinter the resulting plurality of molded particles, thereby providing the plurality of molded particles with extra physical strength without disrupting their pore structure.
  • Typical sintering times are up to 10 hours, such as 5 hours, up to 4 hours, up to 3 hours, or up to 2 hours.
  • Sintering times can be 1 hour or more, such as 2 hours or more, 3 hours or more, or 4 hours or more.
  • the first plurality of molded particles can be ready to use, and typically do not require further processing steps, such as milling, cutting, or shaping, in order to be converted into a desired shape. Instead, the shape of the plurality of molded particles is determined by the shape of the mold. In some cases, depending on the intended use, the plurality of molded particles can be treated with one or more surface modifying agents to modify the surface of the plurality of molded particles.
  • Molded particles that are free of cracks with a maximum dimension greater than 10 micrometers can be useful for many applications, especially those that require molded particles with high structural integrity.
  • the composition comprising a plurality of molded particles can have a variety of uses.
  • a composition comprising a first plurality of molded particles can be used in a variety of articles.
  • One such article is a vacuum insulated glass unit.
  • Such units include two glass planes and an edge seal between the glass planes with a substantial vacuum gap between them.
  • the composition comprising a first plurality of molded particles can be used to separate two sheets of glass in vacuum insulated glass units.
  • a vacuum insulated glass unit In a vacuum insulated glass unit, particles are often laid out as a grid, with the space between the particles ranging from about 20 millimeters to about 45 millimeters.
  • a vacuum insulated glass unit that is 20 cm by 20 cm would have about 81 particles in the first plurality of molded particles if the particles were laid out in a 20 millimeter grid, or about 16 particles in the first plurality of molded particles if the particles were laid out in a 45 millimeter grid.
  • a larger window with a size of one square meter would require a first plurality of particles with about 500 to 2,400 particles, depending on the grid spacing.
  • the number of particles in the first plurality of molded particles can vary depending on the use.
  • the first plurality of molded particles can have 2 or more particles.
  • the number of particles in the first plurality of molded particles can have 10 or more, 20 or more, 50 or more, 75 or more, 100 or more, or 250 or more.
  • number of particles in the first plurality of molded particles can be 500 or more, 1,000 or more, 2,000 or more 5,000 or more, 7,500 or more, 10,000 or more, 20,000 or more, 50,000 or more, 100,000 or more, 200,000 or more, or 300,000 or more. Because of their small size, a large number of particles can be present in a low weight.
  • one kg of a cylindrically shaped plurality of particles having a diameter of 500 micrometers and a height of 500 micrometers would contain approximately 1,685,000 particles. If the cylindrically shaped plurality of particles has a diameter of 500 micrometers and a height of 250 micrometers, then one kg of particles contains approximately 3,369,000 particles.
  • a first plurality of molded particles with those characteristics that weighs 20 kg of includes approximately 33 billion individual particles
  • the number of particles in a first plurality of molded particles can be even larger than those discussed above, such as 500,000 or more, 750,000 or more, 1,000,000 or more, 2,500,000 or more, 5,000,000 or more, 10,000,000 or more, 50,000,000 or more, 100,000,000 or more, 250,000,000 or more, 500,000,000 or more, 750,000,000 or more, 1 billion or more, 2 billion or more, 3 billion or more, 5 billion or more, 10 billion or more, 15 billion or more, 25 billion or more, 50 billion or more, or 100 billion or more.
  • milling processes often leave an artifact, such as a dimple or protrusion, on a milled product.
  • the size and shape of such artifacts are often not well controlled.
  • milling such large numbers of particles can have a prohibitively high cost, especially when compared to processes such as the molding processes discussed herein.
  • Figure 1 shows an example of a plurality of molded particles used in a vacuum insulated glass unit.
  • An insulated glass unit 10 includes a first sheet of glass 11 and a second sheet of glass 12.
  • the first sheet of glass Hand second sheet of glass 12 are separated by a plurality of molded particles 14.
  • An edge seal 13 maintains a vacuum between the first and second sheets of glass, 11 and 12.
  • the plurality of molded particles 14 must maintain their structural integrity in this environment in order to maintain a separation between the first sheet of glass 11 and the second sheet of glass 12.
  • the plurality of molded particles function as spacers to maintain the separation of glass panes and can leave a vacuum gap within an insulated glass unit.
  • the glass panes are substantially co-extensive with one another to make a complete insulated glass unit.
  • the plurality of molded particles are often shaped like a disk having a diameter (largest dimension) of 600 micrometers or less and a thickness of 100 micrometers to 600 micrometers.
  • the plurality of molded particles can have a diameter (largest dimension) of less than 1000 micrometers, or 800 micrometers, or 600 micrometers, or 400 micrometers, or 200 micrometers, or 100 micrometers.
  • the plurality of molded particles can be useful for this application because they can be stable to vacuum glazing fabrication conditions, including high temperature edge frit sealing at temperatures such as 400° C.
  • the plurality of molded particles can also have sufficient physical integrity, such as photo-, mechanical, and thermal stability, which can make them suitable for use in this application because they can be able to withstand years of use in exterior window applications in a number of environments.
  • the first plurality of molded particles can, in some cases, have a compressive strength of greater than 400 MPa, 600 MPa, 800 MPa, 1,000 MPa, or 1,500 MPa.
  • the plurality of molded particles can have a compressive strength that is less than 2,000 MPa, 1,500 MPa, or 1,000 MPa.
  • the first plurality of molded particles can have a thermal conductivity of 10 W m "2 °K _1 or less, 5 W m "2 °K or less, or 3 W m "2 °K _1 or less.
  • the thermal conductivity can be 1 W m "2 °K _1 or greater, 2 W m "2
  • the strength and thermal conductivity described herein can facilitate the first plurality of molded particles maintaining separation between the two planes of glass without adversely affecting the vacuum insulation.
  • the shape of the first plurality of molded particles is determined by the shape of the cavities in the mold used in the fabrication process.
  • a hexagonal or octagonal shape is often used, as illustrated in FIGS. 3A-3F.
  • the plurality of molded particles can include surfaces between the sidewalls for placement against the glass panes of a vacuum insulated glass unit.
  • molded particle 16 which has a tapered hexagonal shape (FIG. 3A).
  • molded particle 17 which has a tapered hexagonal shape with an indentation 18 (FIG. 3B).
  • molded particle 19 which has a tapered hexagonal shape with an indentation 20 and a notch 21 (FIG. 3C).
  • molded particle 22 which has a tapered octagonal shape (FIG. 3D).
  • molded particle 23 which has a tapered octagonal shape with an indentation 24 (FIG. 3E).
  • molded particle 25 which has a tapered octagonal shape with an indentation 26 and a notch 27 (FIG. 3F).
  • molded particle 28 which has a tapered round disk shape (FIG. 3G).
  • molded particle 29 which has a tapered shape with shaped sidewalls (FIG. 3H).
  • Other shapes are possible such as a 12-sided body and non-tapered shapes.
  • the plurality of molded particles can contain functional coatings, as illustrated by the exemplary pillars in FIGS. 3I-3K.
  • a molded particle 151 includes a functional coating 150 (FIG. 31).
  • a molded particle 153 includes a functional coating 152 (FIG. 3J).
  • a molded particle 155 includes a functional coating 154 (FIG. 3K).
  • FIGS. 3A-H show particle sidewalls that are tapered or sloped. Such shaping can improve mold release.
  • FIG. 3L shows a side view of a molded particle having a draft angle between a face 37,which has a smaller area than opposite surface 38, and a sloping sidewall 39.
  • the angle of draft angle can be varied to change the relative sizes of each face 37 and 38.
  • the draft angle is often from 95° to 130°, from 95° to 125°, from 95° to 120°, from 95° to 1 15°, from 95° to 1 10°, from, 95° to 105°, or from 95° to 100°.
  • One or more of the plurality of molded particles can have one or more indentations, as illustrated in
  • FIGS. 3B, 3C, 3E, and 3F Such one or more indentations can facilitate mechanical differentiation of the two major surfaces during a coating, sorting, or positioning process.
  • FIG. 4 illustrates a crevice 30 in a mold having a protrusion 32 for mating with an indentation 33 on a molded particle 31.
  • a molded particle When a molded particle has one or more indentation, it can also have one or more notches in the outermost surface of the indented side, as illustrated in FIGS. 3C and 3F.
  • the plurality of molded particles will have a cross-sectional shape without any excessive roughness or warp.
  • FIG. 5A illustrates a molded particle 34 having such a shape. In some cases, a small amount of warp or roughness can be acceptable.
  • FIG. 5B illustrates a molded particle 35 having roughness
  • FIG. 5C illustrates a molded particle 36 having roughness and warp.
  • the methods disclosed herein can be used to produce compositions comprising a plurality of particles having no excessive roughness or warp, as illustrated in FIG. 5A.
  • the plurality of molded particles can have one or more coatings. Such one or more coatings can facilitate formation of a vacuum insulated glass unit, improve the efficiency of a vacuum insulated glass unit, or both. Such one or more coatings can find use when the first plurality of molded particles are used in applications or articles other than vacuum insulated glass units.
  • a planarization layer is one example of a coating on the plurality of molded particles.
  • Planarization layers can comprise a thermally stable crosslinked composite, which can flatten and smooth one or more surfaces of the plurality of molded particles. Even when the plurality of molded particles have surfaces that are flat and smooth, a planarization layer can be used to provide a compressible layer for fabrication of a vacuum insulated glass to reduce the likelihood of cracking the glass panes in the vacuum insulated glass unit.
  • the planarization layer can comprise an organic, inorganic, or hybrid polymeric binder and, in some cases, an inorganic nanoparticle filler.
  • a polymeric binder layer is another example of a coating on the plurality of molded particles.
  • a polymeric binder layer can include one or more thermally stable organic polymers. Such polymers can be dimensionally stable upon exposures to temperatures up to 350° C. In many cases, the polymeric binder has a low thermal conductivity to reduce the transfer of heat from the exterior of the vacuum insulated glass unit to the interior of the vacuum insulated glass unit.
  • Suitable polymers can include one or more of polyimide, polyamide, polyphenylene, polyphenylene oxide, polyaramide (e.g., products sold under the trade designation KEVLAR), polysulfone, polysulfide, polybenzimidazoles, and polycarbonate.
  • One exemplary polymer that may be used is a polyetherimide manufactured by SABIC Innovative Plastics and sold under the trade designation ULTEM. Another exemplary material is an imide- extended
  • bismaleimide such as the one available from Designer Molecules (San Diego, CA) under the trade designation BMI- 1700, which can be melt-processed at low temperatures and then cured to form a crosslinked polyimide network.
  • the polymeric binder layer can, in some cases, include thermally stable polymers. Such polymers can be dimensionally stable upon exposures to temperatures up to 350° C. Examples of such polymers include amorphous organopolysiloxane networks, which are chemical bond networks derived from condensation of organosiloxane precursors, as well as silsesquioxanes or polysilsesquioxanes, which are derived from fundamental molecular units that have silicon coordinated with three bridging oxygen atoms.
  • Exemplary polysilsesquioxanes include one or more of polymethylsilsesquioxane, polyoctylsilsesquioxane, polyphenylsilsesquioxane and polyvinylsilsesquioxane.
  • the polysilsesquioxanes can be, acrylopoly oligomeric silsesquioxane (Hybrid Plastics of Hattiesburg, Mississippi), polymethylsilsesquioxane available from Techneglas of Columbus, Ohio under the trade designation GR653L, GR654L, and GR650F, polyphenylsilsesquioxane available from Techneglas of Columbus, Ohio under the trade designation GR950F, and polymethylphenylsilsesquioxane available from Techneglas of Columbus, Ohio under the trade designation GR908F.
  • acrylopoly oligomeric silsesquioxane Hybrid Plastics of Hattiesburg, Mississippi
  • polymethylsilsesquioxane available from Techneglas of Columbus, Ohio under the trade designation GR653L, GR654L, and GR650F
  • polyphenylsilsesquioxane available from Techneglas of Columbus, Ohio under the trade designation GR
  • the polymeric binder layer can also comprise other alkoxysilanes, such as tetraalkoxysilanes and alkyltrialkoxysilanes having the formula: (R') x Si-(OR 2 ) y wherein R' can be one or more of alkyl, alkylaryl, arylalkyl, aryl, hydroxyl, polyglycyl, or a polyether radical, R 2 can be one or more of alkyl, acetoxy, or methoxyethoxy, x is from 0 to 3 and y is from 1 to 4, with the proviso the sum of x and y is 4.
  • R' can be one or more of alkyl, alkylaryl, arylalkyl, aryl, hydroxyl, polyglycyl, or a polyether radical
  • R 2 can be one or more of alkyl, acetoxy, or methoxyethoxy
  • x is from 0 to 3
  • y is
  • One or more alkoxysilanes including mono, di, tri, and tetraalkoxysilanes may be added to control the crosslink density of the organosiloxane network, thereby affecting the physical properties of the organosiloxane network. Physical properties affected by crosslmking density include flexibility and adhesion promotion. Examples of such alkoxysilanes include one or more of tetraethoxysilane, tetramethoxysilane, methyltriethoxysilane, and methyltrimethoxysilane. Such ingredients may be present in an amount of about 0 to 50 weight percent based on the weight of the polymeric binder layer.
  • An adhesive layer is still another example of a coating that can be applied to a plurality of molded particles.
  • An adhesive layer can comprise a thermal or radiation sensitive silsesquioxane, a photoinitiator, and a nanoparticle filler. This filler can be crosslinked photochemically and then heated to initiate condensation of the silanol groups of the silsesquioxane, forming a durable, thermally stable material.
  • the adhesive layer can provide adhesion between the plurality of molded particles and the glass panes.
  • An orientation layer is yet another example of a coating that can be applied to a plurality of molded particles.
  • An orientation layer can be applied to the plurality of particles while they are in the one or more molds.
  • the orientation layer can be applied on the mold side or the air side.
  • the orientation layer can physically or chemically differentiate the mold and air sides of the plurality of molded particles.
  • the orientation layer can be any layer that is one or more of electrically conductive, statically dissipative, ferromagnetic, ionic, hydrophobic, or hydrophilic.
  • a frit glass coating is still another example of a coating that can be applied to a plurality of molded particles.
  • a frit glass coating can be dispersion of low melting glass microparticles in a sacrificial binder. It can be applied uniformly to the exterior of the plurality of molded particles.
  • the sacrificial binder can thermally decompose and the frit glass can flow to form an adhesive bond between one or more of the molded particles in the plurality of molded particles and one or both of the glass panes.
  • Exemplary sacrificial polymers include one or more of nitrocellulose, ethyl cellulose, alkylene polycarbonates, (meth)acrylates, and polynorbonenes.
  • the sacrificial polymers can be also act as binders for the frit glass in the frit glass coating.
  • a low coefficient of friction (COF) layer is yet another example of a coating that can be applied to a plurality of molded particles.
  • a low COF layer can be a thermally stable layer that promotes slip between one or more surfaces of the plurality of molded particles and one of the inner glass surfaces in a vacuum insulated glass unit.
  • the low COF layer can comprise a monolayer of fluorosilanes, a fluorinated nanoparticle filled polyimide, such as those sold under the trade designation Corin XLS, from NeXolve, Huntsville, AL, a thin coating of a low surface energy polymer, such as polyvinylidine fluoride or polytetrafluoroethylene, diamond-like carbon (DLC), a lamellar layer comprising graphite, or other thermally stable lubricant materials.
  • a low surface energy polymer such as polyvinylidine fluoride or polytetrafluoroethylene, diamond-like carbon (DLC)
  • DLC diamond-like carbon
  • metal oxide molded particles having a largest dimension that is no greater than 1 cm can also be free of cracks with a maximum dimension of 10 micrometers or greater. This is so because metal oxide compositions with similar chemical content as the molded particles, such as those described in WO 2013/055432 (Kolb) cannot be molded into small sizes, such as 1 cm or less, but instead are tooled to achieve their final size and shape. Further, molding processes that are known to produce metal oxide particles with sizes less than 1 cm, such as those disclosed in US 8123828 (Culler), produce molded particles with significant amounts of fractures (i.e., cracks).
  • Embodiment 1 A composition comprising at least a first plurality of molded particles, each molded particle of the first plurality of molded particles comprising at least 70 mol percent Zr0 2 , wherein the first plurality of molded particles are uniform in shape;
  • each of the molded particles of the first plurality of molded particles has a largest dimension of no more than 1 cm;
  • 80 percent or more of the molded particles of the first plurality of molded particles are free of cracks having a maximum dimension greater than 10 micrometers.
  • Embodiment 2 The composition of embodiment 1, wherein each of the first plurality of molded particles has a largest dimension that is no more than 5 mm.
  • Embodiment 3 The composition of any preceding embodiment, wherein the variation in molded particle volume among the first plurality of molded particles is no more than 10 %.
  • Embodiment 4 The composition of embodiment 3, wherein the variation in molded particle volume among the first plurality of molded particles is no more than 5 %.
  • Embodiment 5 The composition of embodiment 4, wherein the variation in molded particle volume among the first plurality of molded particles is no more than 2 %.
  • Embodiment 6 The composition of any of the preceding embodiments, wherein the first plurality of molded particles have one or more smallest dimensions, and wherein a variation in size of the one or more smallest dimensions is no more than 10 %
  • Embodiment 7 The composition of embodiment 6, wherein the first plurality of molded particles have one or more smallest dimensions, and wherein the variation in size of the one or more smallest dimensions is no more than 5 %.
  • Embodiment 8 The composition of embodiment 7, wherein the first plurality of molded particles have one or more smallest dimensions, and wherein the variation in size of the one or more smallest dimensions is no more than 2 %.
  • Embodiment 9 The composition of any of the preceding embodiments, wherein the first plurality of molded particles have one or more largest dimensions, and wherein a variation in size of the one or more largest dimensions is no more than 10%.
  • Embodiment 10 The composition of embodiment 9, wherein the first plurality of molded particles have one or more largest dimensions, and wherein the variation in size of the one or more largest dimensions is no more than 5%.
  • Embodiment 1 1 The composition of embodiment 10, wherein the first plurality of molded particles have one or more largest dimensions, and wherein the variation in size of the one or more largest dimensions is no more than 2 %.
  • Embodiment 12 The composition of any preceding embodiment, wherein at least 85% of the first plurality of molded particles are free of cracks having a maximum dimension greater than 10
  • Embodiment 13 The composition of embodiment 12, wherein at least 90% of the first plurality of molded particles are free of cracks having a maximum dimension greater than 10 micrometers.
  • Embodiment 14 The composition of embodiment 13, wherein at least 95% of the first plurality of molded particles are free of cracks having a maximum dimension greater than 10 micrometers.
  • Embodiment 15 The composition of any of the preceding embodiments, wherein at least 99% of the first plurality of molded particles are free of cracks having a maximum dimension greater than 10
  • Embodiment 16 The composition any of the preceding embodiments, wherein the cracks having a maximum dimension no greater than 10 micrometers have a maximum dimension no greater than 7 micrometers.
  • Embodiment 17 The composition of embodiment 16, wherein the wherein the cracks having a maximum dimension no greater than 10 micrometers have a maximum dimension no greater than 5 micrometers.
  • Embodiment 18 The composition of embodiment 17, wherein the wherein the cracks having a maximum dimension no greater than 10 micrometers have a maximum dimension no greater than 2 micrometers.
  • Embodiment 19 The composition of any preceding embodiment, further comprising a second plurality of molded particles, the second plurality of molded particles having at least one of a different volume, a different shape, a different chemical composition, a different longest dimension, and a different shortest dimension from the first plurality of molded particles.
  • Embodiment 20 The composition of embodiment 19, wherein the second plurality of molded particles have a different shape from the first plurality of molded particles.
  • Embodiment 21 The composition of any preceding embodiment, wherein each particle of the first plurality of molded particles further comprises from 1 mol percent to 30 mol percent of one or more rare earth oxides.
  • Embodiment 22 The composition of any preceding embodiment, wherein each particle of the first plurality of molded particles further comprises 1 mol percent or more of one or more rare earth oxides.
  • Embodiment 23 The composition of embodiment 22, wherein each particle of the plurality of molded particles further comprises 5 mol percent or more of one or more rare earth oxides.
  • Embodiment 24 The composition of embodiment 23, wherein each particle of the first plurality of molded particles further comprises 10 mol percent or more of one or more rare earth oxides.
  • Embodiment 25 The composition of embodiment 24, wherein each particle of the first plurality of molded particles further comprises 15 mol percent or more of one or more rare earth oxides.
  • Embodiment 26 The composition of embodiment 25, wherein each particle of the first plurality of molded particles further comprises 20 mol percent or more of one or more rare earth oxides.
  • Embodiment 27 The composition of embodiment 26, wherein each particle of the first plurality of molded particles further comprises 25 mol percent or more of one or more rare earth oxides.
  • Embodiment 28 The composition of any of the preceding embodiments, wherein each first particle of the plurality of molded particles further comprises no more than 30 mol percent of one or more rare earth oxides.
  • Embodiment 29 The composition embodiment 28, wherein each particle of the first plurality of molded particles further comprises no more than 25 mol percent of one or more rare earth oxides.
  • Embodiment 30 The composition embodiment 29, wherein each particle of the first plurality of molded particles further comprises no more than 20 mol percent of one or more rare earth oxides.
  • Embodiment 31 The composition embodiment 30, wherein each particle of the first plurality of molded particles further comprises no more than 15 mol percent of one or more rare earth oxides.
  • Embodiment 32 The composition embodiment 31, wherein each particle of the first plurality of molded particles further comprises no more than 10 mol percent of one or more rare earth oxides.
  • Embodiment 33 The composition embodiment 32, wherein each particle of the first plurality of molded particles further comprises no more than 5 mol percent of one or more rare earth oxides.
  • Embodiment 34 The composition of any of embodiments 32-33, wherein each particle of the first plurality of molded particles further comprises from 1 mol percent to 30 mol percent of one or more rare earth oxides.
  • Embodiment 35 The composition of any of claims 21-34, wherein the rare earth oxides comprise Y 2 O 3 .
  • Embodiment 36 The composition of any of claims 21-34, wherein the rare earth oxides comprise La 2 0 3 .
  • Embodiment 37 The composition of any of the preceding embodiments, wherein each particle of the first plurality of molded particles further comprise from 1 mol percent to 15 mol percent Y 2 O 3 .
  • Embodiment 38 The composition of any of the preceding embodiments, wherein each particle of the first plurality of molded particles further comprise from 1 mol percent to 5 mol percent La 2 0 3 .
  • Embodiment 39 The composition of any of the preceding embodiments, wherein each particle of the first plurality of molded particles further comprise from 0.01 mol percent to 0.5 mol percent A1 2 0 3 .
  • Embodiment 40 The composition of any of the preceding embodiments, wherein each particle of the plurality of molded particles comprises at least 0.01 mol percent AI 2 O 3 .
  • Embodiment 41 The composition of embodiment 40, wherein each particle of the first plurality of molded particles comprises at least 0.05 mol percent AI 2 O 3 .
  • Embodiment 42 The composition of embodiment 41 , wherein each particle of the first plurality of molded particles comprises at least 0.1 mol percent AI 2 O 3 .
  • Embodiment 43 The composition of embodiment 42, wherein each particle of the first plurality of molded particles comprises at least 0.25 mol percent AI 2 O 3 .
  • Embodiment 44 The composition of any of the preceding embodiments, wherein each particle of the first plurality of molded particles comprises no more than 0.5 mol percent AI 2 O 3 .
  • Embodiment 45 The composition of embodiment 44, wherein each particle of the first plurality of molded particles comprises no more than 0.25 mol percent AI 2 O 3 .
  • Embodiment 46 The composition of embodiment 45, wherein each particle of the first plurality of molded particles comprises no more than 0.5 mol percent A1 2 0 3 .
  • Embodiment 47 An article comprising the composition of any of the preceding embodiments.
  • Embodiment 48 The article of embodiment 47, further comprising glass.
  • Embodiment 49 The article of embodiment 48, wherein the article is vacuum insulated glass.
  • Embodiment 50 A method of making the composition or article of any of the preceding claims, comprising
  • a sol comprising crystalline metal oxide particles having an average primary particle size no greater than 50 nanometers, wherein at least 70 mol percent of the crystalline metal oxide in the composition is ZrC ⁇ ;
  • Embodiment 51 The method of embodiment 50, further comprising concentrating the sol.
  • Embodiment 52 The method of any of embodiments 50-51, further comprising
  • Embodiment 53 The method of any of embodiments 50-52, wherein the step of adding one or more radically reactive surface modifiers to the sol further comprises adding one or more radical initiators to the sol.
  • Embodiment 54 The method of any of embodiments 50-53, further comprising adding at least one of one or more radically polymerizable monomers and one or more radically polymerizable oligomers to the sol.
  • Embodiment 55 The method of any of embodiments 50-54, wherein the step of polymerizing the one or more radically polymerizable surface modifiers to convert the composition to a cured intermediate comprises initiating polymerization of the radically polymerizable surface modifiers by exposing the radically polymerizable surface modifiers to ultra-violet radiation.
  • Embodiment 56 The method of any of embodiments 50-55, wherein the step of polymerizing the one or more radically polymerizable surface modifiers to convert the composition to a cured intermediate comprises initiating polymerization of the radically polymerizable surface modifiers by exposing the radically polymerizable surface modifiers to heat.
  • Embodiment 57 The method of any of embodiments 50-56, wherein each of the one or more molds comprise a first plurality of first uniformly shaped cavities, the first uniformly shaped cavities comprising polymeric surfaces.
  • Embodiment 58 The method of any of embodiments 50-57, wherein each of the one or more molds comprise a first plurality of first uniformly shaped cavities, the first uniformly shaped cavities comprising metal surfaces.
  • Embodiment 59 The method of any of embodiments 50-58, wherein each of the one or more molds comprise a first plurality of first uniformly shaped cavities, the first uniformly shaped cavities comprising ceramic surfaces.
  • Embodiment 60 The method of any of embodiments 50-59, wherein each of the one or more molds comprise a first plurality of first uniformly shaped cavities, the first uniformly shaped cavities comprising glass surfaces.
  • Embodiment 61 The method of any of embodiments 50-60, wherein each of the one or more molds further comprises a second plurality of second uniformly shaped cavities, wherein the second uniformly shaped cavities have at least one of a size, shape, or volume, that is different from that of the first uniformly shaped cavities.
  • Embodiment 62 The method of embodiment 61, wherein the polymeric surfaces comprise polypropylene.
  • Embodiment 63 The method of any of embodiments 50-62, wherein no release agent is applied to the plurality of cavities.
  • Embodiment 64 The method of any of embodiments 50-63, wherein a release agent is applied to the plurality of cavities.
  • Embodiment 65 The method of embodiment 50-64, wherein the release agent is an oil.
  • Embodiment 66 The method of any of embodiments 50-65, wherein the plurality of cavities has the shape of a disk, cone, cylinder, or polyhedron.
  • Embodiment 67 The method of embodiment 50-66, wherein the polyhedron is pyramidal.
  • HEMA is an abbreviation for (hydroxyethyl)methacrylate
  • HEAA is an abbreviation for N-hydroxyethyl acrylamide
  • IRGACURE 819 is a trade designation for bis(2,4,6-trimethylbenxoyl)-phenylphosphineoxide.
  • a hydrothermal reactor was prepared from 50 feet (15 meters) of Stainless Steel Braided Smooth Tube Hose (DuPont T62 Chemfluor PTFE, 0.25 inch inner diameter., 0.065 inch thick wall tubing available from Saint-Gobain Performance Plastics, Beaverton, Michigan). This tube was immersed in a bath of peanut oil heated to 225°C. A coil of an additional 10 feet (3 meters) of Stainless Steel Braided Smooth Tube Hose (DuPont T62 Chemfluor PTFE, 0.25 inch inner diameter, 0.065 inch thick wall was attached to the tube, andlO feet (3 meters) of 0.25 inch stainless-steel tubing with a diameter of 0.25 inch (0.64 cm) and wall thickness of 0.035 inch (0.089 cm) was attached to the coil. The stainless steel tubing was immersed in an ice-water bath to cool the material and a backpressure regulator valve was used to maintain an exit pressure of 400 psi (pounds per square inch).
  • a precursor solution was prepared by combining the zirconium acetate solution (2,000 g) with DI water (1680 g). Yttrium acetate (126.46 g) and lanthanum acetate (18.62 g) were added and mixed until fully dissolved. The solids content of the resulting solution was measured gravimetrically (120° C/lhr forced air oven) to be 21.6 wt%. Deionized water (517 g) was added to adjust the final concentration to 19 wt%. This procedure was repeated four times to give a total of approximately 17,368 g of precursor material. The resulting solution was pumped at a rate of 1 1.48 mL/min through the hydrothermal reactor at 225°C. The average residence time was 42 min. A clear and stable zirconia sol was obtained. The resulting sol had molar ratio of 93.5/5.0/1.5.
  • the as prepared sol was concentrated to 20-35 wt% solids by ultrafiltration using a membrane cartridge (M2 I S- 100-0 IP available from SpectrumLabs; 18617 Broadwick St. Collinso Dominguez, CA 90220).
  • the final composition was adjusted by one or more of diafiltration, ultrafiltration, and distillation.
  • the final composition of the sol was 49.184% solids, 2.36 mmole acetic acid/g Zr02, with an ethanol:water weight ratio of 68:32.
  • the sol (93.5 mol % Zr0 2 /5 mol % Y 2 0 3 /1.5 mol % La 2 0 3 , 0.05 wt % IRGACURE 819, HEMA) was cast into a polypropylene triangle sheet mold (made by 3M using methods described herein) using a pipette.
  • the mold had arrays of equilateral triangles with 5 mm long sides and a cavity depth of 2 mm.
  • a glass plate coated with a thin layer of Stoner Mold Release was laid on to the sol filled mold and clamped in place.
  • the sol was cured for 2 min using a 460 nm LED light bank. After curing, the triangles released from the mold but stuck to the glass plate.
  • a thin glass cover slide was pushed between the triangle gel pieces and the glass to remove the triangular shaped pieces. These pieces were placed in an aluminum pan and allowed to dry in open air at ambient temperature.
  • the dried triangular shaped pieces were placed on a bed of zirconia beads in an alumina crucible, covered with alumina fiberboard, and heated in air according to the following schedule:
  • calcined triangular shaped pieces were placed on a bed of zirconia beads in an alumina crucible, covered with alumina fiberboard, and heated in air according to the following schedule to form molded particles:
  • the compression strength of the plurality of molded particles was measured using an Instron Model 5500R and ASTM standard C1424- 10: Monotonic Compressive Strength of Advanced Ceramics at Ambient Temperature.
  • the average maximum load was 2,290 N, the average area was 1.540 mm 2 , and the average compression strength was 1.49 x 10 9 Pa.
  • a precursor solution was prepared and processed by a method similar to that described in Example 1 , except that the ratio of Zr0 2 to Y 2 0 3 was 95.76 to 4.24 .
  • the resulting sol was 49.45% solids, 2.27 mmole acetic acid/g Zr0 2 and the ethanol:water weight ratio was 60:40.
  • the sol (95.76 mol% Zr0 2 /4.24 mol% Y 2 0 3 , 0.075 wt% IRGACURE 819, HEAA, acrylic acid) was cast into a polypropylene hexagonal sheet mold.
  • the mold contained hexagonal structures with dimensions of about 1,000 micrometers across by 360 micrometers deep.
  • the sample was prepared in a clean room.
  • the tool was adhered to a 4"x6" (10.16x15 cm) glass plate with double sided tape.
  • the sol was flood coated onto the tool using a pipette. A polyethyleneterephthalate (PET) film was then carefully placed over the filled tool to prevent significant void formation.
  • PET polyethyleneterephthalate
  • a 4"x6" (10.16x15 cm) glass plate was placed on top of the PET and pressure was applied by hand to remove excess sol. The construction was then clamped together. The sol was cured for 2 min using a 420 nm (15 watt) light source. The cured hexagons were removed from the mold and dropped onto a screen to dry.
  • the dried hexagons were placed in an alumina crucible, covered with an alumina crucible cover, and heated in air according to the following schedule:
  • the hexagons were placed in an alumina crucible, covered with alumina fiberboard, and heated in air according to the following schedule:

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Composite Materials (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Joining Of Glass To Other Materials (AREA)

Abstract

Particules d'oxyde métallique, telles que des particules moulées, ainsi que procédés pour leur fabrication et articles les contenant. Les particules peuvent contenir au moins 70 pourcents en moles de Z?r#191O?2#191, et peuvent être obtenues par un procédé par moulage.
EP14772045.2A 2013-09-13 2014-09-12 Particules d'oxyde métallique Withdrawn EP3044185A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US14/025,958 US9878954B2 (en) 2013-09-13 2013-09-13 Vacuum glazing pillars for insulated glass units
US201462048972P 2014-09-11 2014-09-11
PCT/US2014/055389 WO2015038890A1 (fr) 2013-09-13 2014-09-12 Particules d'oxyde métallique

Publications (1)

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EP3044185A1 true EP3044185A1 (fr) 2016-07-20

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EP (1) EP3044185A1 (fr)
JP (1) JP6588913B2 (fr)
CN (1) CN105531240A (fr)
WO (1) WO2015038890A1 (fr)

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Publication number Priority date Publication date Assignee Title
US10550627B2 (en) 2015-03-12 2020-02-04 3M Innovative Properties Company Vacuum glazing pillars for insulated glass units and insulated glass units therefrom
EP3303255B1 (fr) 2015-05-28 2022-06-29 3M Innovative Properties Company Processus de fabrication additive permettant de produire des articles en céramique à l'aide d'un sol contenant des particules de taille nanométrique
US11339095B2 (en) 2015-05-28 2022-05-24 3M Innovative Properties Company Sol containing nano zirconia particles for use in additive manufacturing processes for the production of 3-dimensional articles

Citations (1)

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US5902652A (en) * 1993-06-30 1999-05-11 University Of Sydney Methods of construction of evacuated glazing

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JPH09301775A (ja) * 1996-05-10 1997-11-25 Olympus Optical Co Ltd セラミックスの製造方法
FR2777882B1 (fr) * 1998-04-22 2000-07-21 Produits Refractaires Nouveaux materiaux frittes produits a partir de zircon et de zircone
JP2003246623A (ja) * 2001-06-04 2003-09-02 Sumitomo Chem Co Ltd ジルコニア粉末の製造方法
EP1700829A1 (fr) * 2005-03-09 2006-09-13 Degussa AG Procédé de fabrication d'un monolithe en verre par un procédé sol-gel
CN101573308B (zh) * 2006-12-29 2016-11-09 3M创新有限公司 氧化锆主体以及方法
EP2519478B1 (fr) * 2009-12-29 2018-07-04 3M Innovative Properties Company Materiau au base de zircone dope par yttrium et lanthan
JP2013091585A (ja) * 2011-10-26 2013-05-16 Tosoh Corp ジルコニア粉末及びその製造方法並びにその用途

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US5902652A (en) * 1993-06-30 1999-05-11 University Of Sydney Methods of construction of evacuated glazing

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
SANTA CRUZ H ET AL: "Nanocrystalline ZrO2 ceramics with idealized macropores", JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, ELSEVIER SCIENCE PUBLISHERS, BARKING, ESSEX, GB, vol. 28, no. 9, 1 January 2008 (2008-01-01), pages 1783 - 1791, XP022593592, ISSN: 0955-2219, [retrieved on 20080304], DOI: 10.1016/J.JEURCERAMSOC.2007.12.028 *
See also references of WO2015038890A1 *
X MA ET AL: "High Field Performance of Thin-Wall Spacers in a Vacuum Gap", IEEE TRANSACTIONS ON DICLECFRICS AND ELECTRICAL INSULATION, 1 April 2000 (2000-04-01), pages 277 - 282, XP055521257, Retrieved from the Internet <URL:https://ieeexplore.ieee.org/ielx5/94/18200/00841821.pdf?tp=&arnumber=841821&isnumber=18200> [retrieved on 20181106] *

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JP2016536265A (ja) 2016-11-24
CN105531240A (zh) 2016-04-27
WO2015038890A1 (fr) 2015-03-19
JP6588913B2 (ja) 2019-10-09

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