WO2022026671A1 - Billes de cordiérite à porosité ouverte et articles en céramique fabriqués à partir de celles-ci - Google Patents

Billes de cordiérite à porosité ouverte et articles en céramique fabriqués à partir de celles-ci Download PDF

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Publication number
WO2022026671A1
WO2022026671A1 PCT/US2021/043648 US2021043648W WO2022026671A1 WO 2022026671 A1 WO2022026671 A1 WO 2022026671A1 US 2021043648 W US2021043648 W US 2021043648W WO 2022026671 A1 WO2022026671 A1 WO 2022026671A1
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Prior art keywords
beads
ceramic
cordierite
green
porosity
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PCT/US2021/043648
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English (en)
Inventor
Monika Backhaus-Ricoult
Linda Kay Bohart
Brent Daniel CONWAY
Zachary Andrew FEWKES
Kimberley Louise Work
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Corning Incorporated
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Publication of WO2022026671A1 publication Critical patent/WO2022026671A1/fr

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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
    • C04B35/16—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 silicates other than clay
    • C04B35/18—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 silicates other than clay rich in aluminium oxide
    • C04B35/195—Alkaline earth aluminosilicates, e.g. cordierite or anorthite
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    • 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
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Definitions

  • This disclosure relates to ceramic articles, more particularly to ceramic beads useful in the manufacture of ceramic articles, and more particularly to porous cordierite beads having high open porosities useful to impart a bimodal pore size distribution when used in the manufacture of ceramic articles.
  • Ceramic articles are useful in a number of industries, such as arranged as honeycomb bodies for use as particulate filters and catalytic substrates in the treatment of undesirable components in a fluid stream, such as pollutants in the exhaust of a combustion engine.
  • the process of manufacturing a ceramic article, such as a honeycomb body can include shaping a batch mixture into a green body and firing the green body to convert the green body into the ceramic article.
  • the chemical and physical features and properties of the ceramic article can be influenced by the components (raw ingredients) of the batch mixture.
  • the ceramic powder comprises a plurality of porous ceramic beads, the ceramic beads having a median particle size of at least 20 ⁇ m; a median pore size of less than 4 ⁇ m; and an open porosity of at least 12%.
  • the beads have a closed porosity of at most 5%.
  • the beads have a closed porosity of at most 2.5%.
  • the median particle size is at least 25 ⁇ m.
  • the median particle size is from 20 ⁇ m to 55 ⁇ m.
  • the median particle size is from 25 ⁇ m to 45 ⁇ m.
  • the median pore size is at most 3 ⁇ m.
  • the median pore size is at most 2.5 ⁇ m.
  • the median pore size is from 1 ⁇ m to 4 ⁇ m.
  • the median pore size is from 1 ⁇ m to 2 ⁇ m.
  • the open porosity of the cordierite beads is at least 15%.
  • the open porosity of the cordierite beads is at least 20%.
  • the open porosity of the cordierite beads is at least 25%.
  • the open porosity of the cordierite beads is at least 30%.
  • the porous ceramic beads are at least 80 wt% cordierite.
  • the porous ceramic beads are at least 85 wt% cordierite.
  • crystalline phases of the porous beads are at least 90 wt% cordierite.
  • crystalline phases of the porous beads are at least 95 wt% cordierite.
  • batch mixtures comprising the ceramic powder according to any of the embodiments disclosed herein.
  • the batch mixture comprises the ceramic powder in an amount of at least 80 wt% relative to a total weight of inorganics in the batch mixture.
  • the batch mixture comprises the ceramic powder in an amount of at least 85 wt% relative to a total weight of inorganics in the batch mixture.
  • the batch mixture comprises the ceramic powder in an amount of at least 90 wt% relative to a total weight of inorganics in the batch mixture.
  • the batch mixture further comprises a liquid vehicle and an organic binder.
  • the batch mixture further comprises a pore former.
  • the green article comprises a green honeycomb body.
  • methods of manufacturing a ceramic article comprising shaping the batch mixture of any of the embodiments disclosed herein into a green body and firing the green body to create the ceramic article by sintering the beads together into an interconnected network.
  • the method of manufacturing comprises shaping the batch mixture into a honeycomb body.
  • the shaping comprises extruding the batch mixture through a honeycomb extrusion die.
  • the firing comprises heating the green body to a top temperature at a heating rate of at least 150°C/h.
  • the firing comprises heating the green body to a top temperature at a heating rate of at least 200°C/h.
  • the firing comprises heating the green body to a top temperature at a heating rate of at least 250°C/h.
  • the firing comprises heating the green body to a top temperature at a heating rate of at least 300°C/h.
  • the firing comprises maintaining the tope temperature for a hold time of at most 8 hours.
  • the firing comprises maintaining the tope temperature for a hold time of at most 6 hours.
  • the method comprises spheroidizing a slurry mixture comprising ceramic precursors into a plurality of spheroidal green agglomerates having a median agglomerate size of at least 25 ⁇ m; and firing the green agglomerates to manufacture the ceramic powder as a plurality of ceramic porous beads formed from the green agglomerates by converting the ceramic precursors into at least one ceramic phase of the ceramic porous beads, wherein the firing comprises heating the green agglomerates at a top temperature and for a hold time sufficient to result in the ceramic porous beads having: a median bead size of at least 20 ⁇ m; a median pore size of less than 4 ⁇ m; and an open porosity of at least 12%.
  • the ceramic precursors are cordierite-forming precursors.
  • the cordierite-forming precursors comprise clay, talc, alumina, silica, spinel, or a combination including at least one of the foregoing, in stoichiometric amounts to result in the at least one ceramic phase comprising at least 90 wt% cordierite.
  • the slurry mixture comprises talc having a maximum dimension that is at most 40% of the median particle size of the median bead size.
  • the top temperature is at least 1250°C.
  • the top temperature is at least 1300°C.
  • the top temperature is at least 1350°C.
  • the top temperature is at least 1400°C.
  • the hold time is at most 10 hours.
  • the hold time is at most 8 hours.
  • the hold time is at most 6 hours.
  • the hold time is from 4 hours to 8 hours.
  • FIG. 1 shows a spheroidal ceramic bead according to one embodiment disclosed herein.
  • FIGS. 2A-2C schematically illustrate a first ceramic bead having a high open porosity formed by interconnected narrow pore channels, a second ceramic bead having a high open porosity formed by thin pore channels connected between relatively wide pore voids, and a third ceramic bead having a high open porosity formed by relatively wide interconnected pore channels and relatively wide pore voids.
  • FIG. 3 illustrates various stages for making spheroidal ceramic beads according to one embodiment disclosed herein.
  • FIG. 4 schematically illustrates a honeycomb body according to one embodiment disclosed herein.
  • FIG. 5 illustrates a plugged honeycomb body according to one embodiment disclosed herein.
  • FIG. 6 schematically illustrates through-wall gas flow in a plugged honeycomb body according to one embodiment disclosed herein.
  • FIG. 7 schematically illustrates an extrusion system for forming green honeycomb bodies according to one embodiment disclosed herein.
  • FIG. 8A schematically illustrates a portion of a wall of a ceramic honeycomb body comprising a network of spheroidal ceramic beads according to one embodiment disclosed herein.
  • FIG. 8B shows a cross-sectional scanning electron microscope (SEM) image of a portion of intersecting walls of a ceramic honeycomb body according to one embodiment disclosed herein.
  • FIG. 9 shows a magnified view of a network of spheroidal ceramic beads according to one embodiment disclosed herein.
  • FIG. 10 shows a cross-sectional SEM image of a portion of a network of spheroidal ceramic beads according to one embodiment disclosed herein.
  • FIG. 11 shows a flow chart of a method for making spheroidal ceramic beads, and for manufacturing ceramic honeycomb bodies from batch mixtures comprising the spheroidal ceramic beads.
  • FIGS. 12A-12H are SEM images showing on-surface views and cross-sectional views of green agglomerates according to various embodiments disclosed herein.
  • FIGS. 13A-13D show cross-sectional SEM images of green agglomerates and resulting ceramic beads formed by firing at various top temperatures according to various embodiments disclosed herein.
  • FIG. 14 shows SEM images of fired agglomerated powders obtained by firing spray dried green agglomerates, and firing of a first type and a second type of green agglomerates made by an agglomeration process in a rotary evaporator.
  • FIG. 15A and 15B show SEM images of fracture surface views of the intersecting walls of a ceramic honeycomb body at different magnifications, which walls comprise a network of spheroidal ceramic beads sintered together, according to one embodiment disclosed herein.
  • FIGS. 15C and 15D show respective SEM images of a cross-sectional view and an on- wall view of the intersecting walls of a ceramic honeycomb body, which walls comprise a network of spheroidal ceramic beads sintered together, according to one embodiment disclosed herein.
  • porous ceramic spheroidal particles comprising such porous ceramic particles, and methods for making such porous ceramic particles and for making such ceramic articles are disclosed.
  • the ceramic articles comprise porous ceramic honeycomb bodies.
  • select channels of the honeycomb bodies are plugged to arrange the honeycomb bodies as particulate or wall-flow filters.
  • the porous ceramic spheroidal particles may be referred to herein as “porous ceramic beads”, “ceramic beads” or simply “beads”.
  • the ceramic beads referred to herein are spheroidal ceramic particles comprising a porous ceramic material that comprises one or more ceramic phases, such as cordierite.
  • porous cordierite beads are formed by spheroidizing a slurry mixture comprising cordierite-forming precursors and then firing the spheroidal green agglomerates that result from the spheroidizing.
  • the components (raw ingredients) of the slurry mixture can be set such that the material of the ceramic beads has a high open porosity (the porosity of the material of the ceramic beads may be referred to herein as the intrabead porosity). Due to the spheroidal nature of the beads, the spheroidal packing of the beads when arranged together in a ceramic article creates pores in the form of the voids or interstices between the beads.
  • the porosity of the material of the beads (“intrabead porosity”) and the voids or interstices between the beads (“interbead porosity”) creates a bimodal porosity for the resulting ceramic article made from the high open porosity beads described herein.
  • this bimodal porosity can provide advantageous characteristics for the ceramic article, such as when employed in ceramic honeycomb bodies for the purposes of fluid treatment, e.g., engine exhaust aftertreatment.
  • the resulting bimodal porosity of the microstructure of the ceramic article described herein exhibits unique performance characteristics, such as when arranged as a honeycomb body of a particulate filter or catalyst substrate useful in the treatment, reduction, or abatement of one or more substances (e.g., pollutants) from a fluid stream (e.g., engine exhaust).
  • substances e.g., pollutants
  • the bimodal porosity enables honeycomb bodies to be arranged as particulate filters having high filtration efficiency (FE) even when clean (before ash/soot build up), and which maintain low pressure drop at all levels of ash/soot loading. That is, the open intrabead porosity provides high surface area to provide anchor sites for ash, soot, or other particulate and the relatively smaller pore sizes of the intrabead pore size distribution facilitates capillary action to assist in trapping ash, soot, or other particles at the anchor sites, while the relatively larger pore sizes of the interbead pore size distribution provide relatively large flow passages that maintain low pressure drop even at high particulate loading.
  • FE filtration efficiency
  • the aforementioned bimodal porosity enables a high catalyst material loading to be employed without a significant tradeoff in pressure drop, particularly for a catalyst-loaded particulate filter. That is, the high open porosity offered by the combination of interbead and intrabead porosities provides a high pore volume into which the catalyst material can be loaded and/or a large pore surface area to which the catalyst can be bonded, all while preserving a high interconnectivity of the interbead pore channels.
  • the relatively smaller pore sizes of the intrabead pore size distribution relative to the interbead pore size distribution facilitates capillary action to assist in drawing the catalyst material onto and/or into the beads, while the relatively larger pore sizes of the interbead pore size distribution provide relatively large flow passages that maintain low pressure drop.
  • FIG. 1 an image obtained via scatter electron microscopy (SEM) of an example of a porous cordierite bead 122 is shown.
  • the beads 122 formed as spheroidal ceramic particles, can have one or more shapes such as spheres, ellipsoids, oblate spheroids, prolate spheroids, or toroids.
  • FIGS. 2A-2C Various embodiments for the beads 122 are also schematically illustrated in FIGS. 2A-2C, respectively identified as beads 122A-122C, in which the beads 122 are illustrated in partial cutaway to show both a portion of the exterior and of the interior of each bead.
  • the porous cordierite beads 122 comprise an interconnected open pore structure 124, extending throughout each of the beads 122.
  • the open pore structure 124 can comprise a combination of relatively elongated pore structures, e.g., channels, and/or relatively widened pore structures, e.g., pore voids or pore bodies, with the channels acting as pore necks or throats into the voids or bodies.
  • the pore structure 124 is considered “open” since the pores within the beads 122 are in fluid communication with the exterior of the beads 122.
  • the pore structures 124 comprise openings 126 in the outer surfaces of the beads 122 that enable fluid communication between the interiors and exteriors of the beads 122.
  • the pore structures 124 may also be considered “interconnected” as the pores throughout the beads 122 form a network that is in fluid communication throughout the bead 122 and to the exterior of the bead 122.
  • the open pore structures 124 described herein facilitate flow into, through, and out of the beads 122.
  • at least 80%, at least 85%, or even at least 90% of the porosity of the beads 122 is an open porosity (as opposed to a closed porosity, which would not be in fluid communication with the exterior of the beads).
  • the bead 122 has an open porosity (relative to the total volume of the bead 122) of at least 10%, at least 12%, at least 15%, at least 18%, at least 20%, at least 25%, or even at least 30%, including ranges with these values as end points, such as from 12% to 15%, from 12% to 18%, from 12% to 20%, from 12% to 25%, from 12% to 30%, from 12% to 35%, from 15% to 18%, from 15% to 20%, from 15% to 25%, from 15% to 30%, from 12% to 35%, or even from 20% to 25%, from 20% to 30%, or from 20% to 35%.
  • the closed porosity of the porous ceramic beads is at most 5%, at most 4%, at most 3%, or even at most 2.5%, including ranges with these values as end points, such as from 0% to 5%, from 0% to 4%, from 0% to 3%, or from 0% to 2.5%.
  • the bead 122A has an open pore structure that comprises an interconnected plurality of relatively narrow pore channels extending throughout the bead 122 A.
  • the bead 122B comprises an open pore structure that comprises an interconnected plurality of relatively narrow pore channels interspaced with pore voids or bodies of relatively larger diameter.
  • the bead 122C comprises an open pore structure that comprises an interconnected plurality of relatively broad pore channels interspaced with and connected between pore voids or bodies of relatively larger diameter.
  • relatively narrower pores e.g., the channels of beads 122A and/or 122B
  • relatively wider pores e.g., the voids in beads 122B and 122C
  • relatively wider (larger) pores can be particularly advantageous, when used to manufacture a honeycomb body, for hosting catalyst particles and/or storing ash, while increased pore surface area can be beneficial for providing anchor sites for ash or catalyst particle.
  • the beads 122 can be formed by preparing a batch mixture of ceramic-forming materials (e.g., ceramic and/or ceramic precursor materials), spheroidizing the batch mixture into green agglomerates, and then firing the green agglomerates to sinter and/or react the ceramic-forming materials into one or more selected ceramic phases, e.g., cordierite.
  • ceramic-forming materials e.g., ceramic and/or ceramic precursor materials
  • the batch mixture utilized to form the green agglomerates may be referred to as a precursor slurry mixture or simply as a slurry mixture.
  • Spheroidizing processes include spraydrying and rotary evaporation, among others.
  • the median particle size or diameter of the beads is at least at least 20 ⁇ m, at least 25 ⁇ m, or even at least 30 ⁇ m. In some embodiments, the median particle size of the beads is at most about 55 ⁇ m, such as at most 50 ⁇ m, or at most 45 ⁇ m.
  • the median particle size of the beads ranges from about 20 ⁇ m to 55 ⁇ m, such as from 25 ⁇ m to 55 ⁇ m, from 25 ⁇ m to 50 ⁇ m, from 25 ⁇ m to 45 ⁇ m, or from 25 ⁇ m to 40 ⁇ m, from 30 ⁇ m to 55 ⁇ m, from 30 ⁇ m to 50 ⁇ m, from 30 ⁇ m to 45 ⁇ m, or from 30 ⁇ m to 40 ⁇ m.
  • beads having a median particle size of less than 20 ⁇ m and/or 25 ⁇ m are used in combination with beads having a median particle size larger than 25 ⁇ m, such as a first type of bead having a median particle size in the range from 15 ⁇ m to 20 ⁇ m used in combination with a second type of bead having a median particle size in the range from 30 ⁇ m to 50 ⁇ m, with the combined median bead size being in the ranges disclosed herein.
  • the beads 122 can be formed as ceramic particles by firing green agglomerates of ceramic-forming raw materials under conditions (e.g., time and temperature) suitable to cause reaction of the ceramic-forming mixtures into one or more ceramic phases and/or sintering of ceramic grains together.
  • cordierite may form at firing temperatures between about 1200°C to about 1420°C.
  • firing of green agglomerates can range from about half an hour to about 6-8 hours at the selected firing temperature, with greater degrees of reaction (and thus higher percentages of ceramic phase(s) formed) at longer durations and higher temperatures.
  • FIG. 3 illustrates representative stages (A)-(E) that can occur during manufacture of the beads 122 from green agglomerates according to some embodiments.
  • the green agglomerates e.g., arranged as a powder of spheroidal particles of agglomerated slurry mixture ingredients, can be fired to partial or full reaction to preserve the spheroidal shape of the green agglomerates for the ceramic beads 122 the result from firing. Firing may result in the green agglomerates undergoing a number of reactions, starting with the binder, dispersant, and other organic material burn out, water loss of the inorganic materials, and decomposition of any carbonates under release of CO 2 .
  • the onset of solid state reactions may begin at temperatures of between about 1000°C and 1200°C.
  • a green agglomerate 130 is formed as a spheroidal particle comprising ceramic-forming materials.
  • the green agglomerates 130 can be formed from an agglomerate slurry mixture that comprises inorganic ceramic-forming materials (e.g., ceramic and/or ceramic precursor materials), such as talc, clay, alumina, boehemite, silica, magnesia (e.g., Mg(OH) 2 or MgO), spinel, etc., that will form the one or more ceramic phases of the ceramic beads 122 during firing, one or more binders (e.g., styrene acrylic polymer or other polymer) for temporarily holding the shape of the green agglomerates 130 before firing, pore formers (e.g., resin, starch, graphite) to add additional porosity to the beads 122 if desired, dispersant to maintain loose particle packing, and any other additives (e.g., surfactants or antif
  • inorganic raw materials used for making 15-50 ⁇ m sized green agglomerates which can be fired to form cordierite beads of similar size, can have raw material median particle sizes in the range of about 3-5 ⁇ m or smaller, with d90 values of the raw material ingredients typically less than 7 ⁇ m, which particle sizes assist in achieving high open porosities and other properties disclosed herein.
  • the green agglomerates 130 can be made by a spheroidizing process, such as spray drying or rotary evaporation.
  • a spheroidizing process such as spray drying or rotary evaporation.
  • wet droplets dry in the spray dryer and/or during mixing and transform (e.g., shrink and/or condense) under water loss into the green agglomerate 130.
  • Spraydrying and rotary evaporation can thus be used to efficiently produce a powder of dried green agglomerates 130. The drying can occur quickly under high air flow at elevated temperature.
  • the spheroidal shape of the green agglomerate 130 (e.g., that exits the spray dryer nozzle and/or is formed by rotary evaporation) can exhibit high solid loading and a low density of raw material particle packing, particularly of platy raw material particles such as talc.
  • the solid loading is between about 10% and 30% by volume.
  • the binder in the agglomerate slurry mixture assists in holding together the green agglomerates 130 so that the loose particle packing can be preserved.
  • stages (B)-(E) of FIG. 3 show the green agglomerates 130 after being fired for increasing amounts of time.
  • Stage (B) shows an early firing stage in which binder materials are burned out and any remaining water is removed (including from hydrated materials), but at which chemical reactions between ceramic-forming precursor materials are not yet occurring.
  • the removal of the liquid vehicle can cause a migration of the fine solid particles (e.g., less than 2 ⁇ m) toward the outer surface of the agglomerate as the liquid vehicle is wicked to the outer surface and evaporated. This may result in the formation of a green shell 132 of particles at the outer surface of the agglomerate.
  • the thickness of the green shell 132 can be altered based on the raw materials in the agglomerate slurry. For example, silica soot, colloidal silica, and other fine oxide particles (e.g., median particle size less than 1 ⁇ m) may in particular contribute to the formation of the green shell 132 and increase the thickness of the green shell 132.
  • stage (C) of FIG. 3 some solid state reactions have occurred between the different ceramic-forming precursor materials.
  • formation of one or more ceramic phases may have begun, and thus, the green agglomerate 130 has begun to transform into the ceramic bead 122.
  • reaction is limited to the contact points between adjacent precursor particles, so the ceramic precursors have not fully reacted to their corresponding ceramic phases.
  • Further reaction of the ceramic precursors to achieve a greater amount of the selected ceramic phase is desirable in some embodiments to more fully establish the corresponding physical properties (e.g., strength) of the ceramic beads 122.
  • the particles forming the green shell 132 has begun reacting into a ceramic shell 133 that assists in stabilizing and strengthening the beads 122.
  • stage (D) reaction of the ceramic precursor materials spreads from the initial contact points through the ceramic precursor particles. Accordingly, at stage (D), the one or more ceramic phases are fully or mostly formed and the physical properties of the beads 122 are largely established, e.g., thereby providing strength and toughness to prevent the beads 122 from being crushed during subsequent mixing and extrusion processes. At stage (D), the ceramic bead 122 also exhibits the open pore structure 124.
  • shrinkage of the bead 122 due to reaction of the ceramic precursors is limited at this stage, since the ceramic shell 133 assists in stabilizing and preserving the spheroidal shape as the green agglomerates 130 transition into the ceramic beads 122 during firing.
  • the resulting ceramic shell 133 may sinter together with few, or without any, of the openings 126, thereby inhibiting the formation of open pore channels to the exterior surface and resulting in hollow ceramic spheroidal particles.
  • the ingredients of the agglomerate slurry mixture can be selected to provide a sufficient amount of fine particles that create the green shell 132 and resulting ceramic shell 133, but at a thickness that permits the formation of the openings 126 in the shell 133 during firing.
  • the selection of the binder package and green agglomerate 130 formation conditions e.g., spray dryer settings
  • the selection of the binder package and green agglomerate 130 formation conditions can be selected to assist in migration of the fine raw material particles to the agglomerate surface to promote formation of the green shell 132 (so that the spheroid shape and size is preserved during firing), but only to a thickness that permits the openings 126 to still be formed in the shell 133 during solid state reaction of fine ceramic precursor materials during later firing and reaction stages.
  • the slurry mixtures can be formed in green agglomerates 130 via spheroidizing processes such as spray drying or evaporative mixing.
  • the slurry mixtures of Tables 1-4 pertain to green agglomerates that can be fired to form the porous ceramic beads 122 as cordierite-containing beads. All values in Tables 1- 4 are given as weight percent, or weight percent super addition (wt% SA) as indicated.
  • wt% SA weight percent super addition
  • the values provided in micrometers ( ⁇ m) in parenthesis in the headings for some of the listed ingredients indicate an approximate median particle size for the corresponding ingredient.
  • the slurry mixtures can be aqueous-based (water as a liquid vehicle) with a ceramic powder dispersant and/or binder to assist in stabilization, although oils, alcohols, or other liquid vehicles could be used with suitable additives to form spheroidal green agglomerates.
  • 2 - 3% styrene acrylic copolymer such as the Duramax B1002 material commercially available from The Dow Chemical Company
  • 0.2% - 1% ammonium salt of acrylic polymer such as Duramax D-3005 material commercially available from The Dow Chemical Company
  • wt% SA weight percent super addition
  • Sodium stearate or other materials can also be added as a sintering aid to assist in formation of the ceramic beads during firing of the green agglomerates.
  • Table 1 Slurry Mixtures with Clay
  • Table 2 Slurry Mixtures with Hydrous Clay, Hydrated Alumina, and Silica Soot
  • the cordierite-forming slurry mixtures comprise a silica source, an alumina source, and a magnesia source.
  • the silica source can be a clay (such as kaolin clay, kyanite clay, and/or hydrous clay), silica, silica soot, talc, clay, or other or silicon-containing compound.
  • the alumina source can be, for example, a clay (such as kaolin clay, kyanite clay, or hydrous clay), alumina, hydrated alumina, spinel, or other aluminum-containing compound.
  • the magnesia source can be, for example, talc, spinel, magnesium hydroxide, or other magnesium- containing compound.
  • the ceramic precursors, e.g., the silica source, alumina source, and magnesia source can be combined in amounts according to stochiometric ratios to create the desired ceramic phase, or phases, such as cordierite having the general formula of Mg 2 Al 4 Si 5 O 18 including in amounts that provide phases stable with small deviations in stoichiometry, composition, and substitution.
  • the sources of alumina, silica, and magnesia are provided in ratios to form the desired primary ceramic phase, e.g., cordierite, in an amount of at least 80 wt% of the ceramic article (and/or cordierite in an amount of at least 90 wt% of crystalline phases).
  • the silica source, alumina source, and magnesia source are selected as cordierite precursors to provide a cordierite composition consisting essentially of from about 49 to about 53 percent by weight SiO 2 , from about 33 to about 38 percent by weight AI 2 O 3 , and from about 12 to about 16 percent by weight MgO.
  • the beads 122 can be added to a batch mixture, which is formed into a green body and then fired to form a ceramic article.
  • a ceramic article is illustrated in the form of a honeycomb body 100, comprising intersecting walls 102 that form a plurality of channels 104.
  • the walls 102 comprise a porous ceramic material.
  • the walls 102 and channels 104 in this way form a honeycomb structure that is encased by a skin or outer peripheral surface 105.
  • the channels 104 extend in direction of the axis through the honeycomb body 100, e.g., parallel to one another, from a first end face 106 to a second end face 108.
  • the honeycomb body 100 can be utilized in a variety of applications, such as for use in a catalytic converter (e.g., the walls 102 acting as a substrate for catalytic material) and/or as a particulate filter (e.g., in which some of the channels 104 are plugged to trap particulate within the honeycomb walls 108).
  • a catalytic converter e.g., the walls 102 acting as a substrate for catalytic material
  • a particulate filter e.g., in which some of the channels 104 are plugged to trap particulate within the honeycomb walls 108.
  • Such honeycomb bodies 100 can thus assist in the treatment or abatement of pollutants from a fluid stream, such as the removal of undesired components from the exhaust stream of a combustion engine of a vehicle.
  • the porous material of the walls 102 can be loaded with a catalytic material such as a three-way catalyst to treat one or more compounds in a fluid flow (e.g., engine exhaust) through the channels
  • some of the channels 104 of the honeycomb body 100 can be plugged with plugs 109 in order to form a plugged honeycomb body 101.
  • the channels are separated into “inlet channels” that are open at the inlet face (e.g., the first end face 106) and “outlet channels” that are open at the opposite outlet face (e.g., the second end face 108).
  • the inlet channels are designated with reference numeral 104a and the outlet channels are designated with reference numeral 104b, with general reference to “the channels 104” including all channels regardless of whether they are inlet or outlet channels.
  • the plugged honeycomb body 101 can form part of, or alternatively be referred to, or considered as, a particulate filter or wall-flow filter (these terms being generally interchangeable).
  • Plugging with plugs 109 can be performed using any suitable plugging process (e.g., patty plugging, slurry plugging, etc.) and plugging material (e.g., a cold set plugging cement).
  • plugging material e.g., a cold set plugging cement
  • some of the channels 104 are plugged at the first end 106, while some of the channels 104 not plugged at the first end 106 are plugged at the second end 108.
  • Any suitable plugging pattern can be used. For example, alternating ones of the channels 104 can be plugged at the opposite ends 106, 108.
  • a fluid flow stream F e.g., engine exhaust
  • the inlet channels 104a of the plugged honeycomb body 101 that are opened at the inlet side (e.g., the end face 106 in FIG. 6)
  • the porous material of the walls 102 that are open at an outlet end (e.g., the end face 108 in FIG. 6).
  • At least some particulate matter in the flow stream F will be prevented from flowing through the porous material of the walls 102 (e.g., those particles that become trapped in the pore structures of the walls 102), thereby treating the flow stream F as it exits the plugged honeycomb body 101.
  • the honeycomb body 100 can be formed in any suitable manner.
  • an extruding system (or extruder) 10 capable of at least partially forming the honeycomb body 100 is illustrated in FIG. 7.
  • the extruder 10 comprises a barrel 12 extending in direction 14 (e.g., the direction of extrusion).
  • a material supply port 16 e.g., which can comprise a hopper or other material supply structure, can be provided to supply a ceramic- forming mixture 110 (alternatively referred to as a batch mixture) into the extruder 10.
  • An extrusion die 18 is coupled at a downstream side of the barrel 12 to shape the batch mixture 110 into a desired shape that is extruded from the extruder 10 as an extrudate 112.
  • the extrusion die 18 can be a honeycomb extrusion die for producing the extrudate 112 as green honeycomb extrudate.
  • the extrusion die 18 can be coupled to the barrel 12 by any suitable means, such as bolting, clamping, or the like.
  • the extrusion die 18 can be preceded by other extruder structures in an extrusion assembly 20, such as a particle screen, screen support, a homogenizer, or the like to facilitate the formation of suitable flow characteristics, e.g., a steady plug-type flow front as the batch mixture 110 reaches the extrusion die 18.
  • extrusion assembly 20 such as a particle screen, screen support, a homogenizer, or the like to facilitate the formation of suitable flow characteristics, e.g., a steady plug-type flow front as the batch mixture 110 reaches the extrusion die 18.
  • the extruder 10 can be any type of extruder, such as a twin-screw or a hydraulic ram extruder, among others.
  • the extruder 10 is illustrated as a twin-screw extruder comprising a pair of extruder screws 22 that are mounted in the barrel 12.
  • a driving mechanism 24, e.g., located outside of the barrel 12, can be included to actuate the extrusion element(s), such as the ram of a ram extruder or the screws 22 in the embodiment of FIG. 7.
  • the extrusion element of the extruder e.g., the pair of extruder screws 22, ram, etc., can operate to move the batch mixture 110 through the barrel 12 with pumping and mixing action in the longitudinal direction 14, which also corresponds to the extrusion direction.
  • the extruder 10 further comprises a cutting apparatus 26.
  • the cutting apparatus 26 is configured to cut a green honeycomb body 100G from the extrudate 112.
  • the green honeycomb body 100G generally resembles the honeycomb body 100, i.e., comprising a honeycomb structure of intersecting walls and channels, since the final ceramic honeycomb body 100 is made by further processing of the green body 100G. That is, after extrusion and cutting, the green body 100G can be further cut or ground to a desired axial length, dried, and fired, among other manufacturing steps, to produce the final ceramic honeycomb body.
  • the green body 100G can be extruded with a skin (i.e., forming the skin 105) or the skin can be added in a subsequent manufacturing step.
  • the ceramic-forming mixture 110 can be introduced to the extruder 10 continuously or intermittently.
  • the ceramic-forming mixture 110 comprises porous ceramic beads according to the various embodiments disclosed herein.
  • the ceramic-forming mixture can further comprise one or more additional inorganic materials (e.g., alumina, silica, talc, clay or other ceramic materials, ceramic precursor materials or green agglomerated ceramic precursor powders), binders (e.g., organic binders such as methylcellulose), pore formers (e.g., starch, graphite, resins), a liquid vehicle (e.g., water), sintering aids, lubricants, or any other additives helpful in the creation, shaping, processing, and/or properties of the extrudate 112, the green honeycomb body 100G, and/or the ceramic honeycomb body 100.
  • additional inorganic materials e.g., alumina, silica, talc, clay or other ceramic materials, ceramic precursor materials or green agglomerated ceramic precursor powders
  • the ceramic-forming mixture 110 comprises a plurality of porous ceramic beads, which ultimately form the porous ceramic material of the walls 102 of the honeycomb body 100.
  • the walls 102 have a microstructure that comprises an interconnected network 120 of porous ceramic beads 122. That is, a plurality of the beads 122 are bonded together into a continuous network, such as by sintering and/or reaction of ceramic and/or ceramic-forming materials during firing of the green body 100G.
  • the beads 122 can be directly sintered together and/or indirectly bonded together (e.g., via sintering and/or reaction of one or more other inorganic materials in the mixture 110).
  • the extrusion die 18 or other shaping mechanism can be utilized to arrange the interconnected network 120 of the beads 122 to define the shape and/or dimensions of the honeycomb body 100, such as a wall thickness t of the wall 102 shown in FIGS. 8A-8B.
  • a total volume of the wall 102 and/or of the interconnected network 120 can thus be defined by the wall thickness t, multiplied by the other cardinal dimensions of the wall 102 and/or the network 120 generally delineated by the outer bounds of the beads 122.
  • the porous ceramic beads 122 may be referred to as or considered as “pre-reacted” beads since they already comprise one or more selected ceramic phases when incorporated in the batch mixture 110 (i.e., and thus, these ceramic phases are already present in the green body 100G before firing of the honeycomb body 100).
  • the beads 122 can be fully reacted, such that continued firing does not result in a greater amount of the ceramic phase(s), or at least partially reacted so that one or more ceramic phases exist, but will continue to react when the beads 122 are subjected to further firing.
  • the “pre-reacted” nature of the beads 122 can be used to preserve the spheroidal shape of the beads during the various manufacturing steps (e.g., batch paste mixing, extrusion, cutting, drying, and firing).
  • a partially or fully reacted ceramic have higher strength than unreacted agglomerates so that crushing of the beads 122 during processes such as extrusion is prevented.
  • the ceramic beads 122 already having one or more reacted phases, more readily undergo continuation of reaction or sintering within each individual bead, as opposed to reaction with unreacted ceramic precursor materials in the other beads.
  • reaction of components from different beads may be limited as there are no material diffusion paths between beads that are not in contact with each other, and only limited diffusion paths for beads in point to point contact.
  • a significant degree of matter transport between reactive components were enabled, e.g., at high temperature due to the presence of high quantities of glass or liquid, then the material would not have this confinement, which would promote the growth of large unstructured agglomerates or large elongated crystals, instead of maintaining the spheroidal bead shapes.
  • the aforementioned interconnected network 120 of the beads 122 can be created for the ceramic honeycomb body 100.
  • FIGS. 9 and 10 show a photograph and a polished SEM cross sectional view, respectively, of portions of interconnected networks 120 of the beads 122 according to some embodiments. From these figures, it can be appreciated that formation of the interconnected network 120 of beads 122 results in interstices 128 (which may be alternatively referred to as spaces or gaps) formed between neighboring ones of the beads 122. That is, the interstices 128 are correspondingly formed due to the packing of the spheroidal shapes of the beads. Thus, in three-dimensional space, the interstices 128 form an open and interconnected pore structure that is intertwined with, between and/or about the interconnected network 120 of the beads 122.
  • interstices 128 which may be alternatively referred to as spaces or gaps
  • the openness and interconnectedness of the open pore structures 124 of the beads 122 and the interstices 128 between the beads can be used to provide various characteristics and/or benefits for the honeycomb body 100, such as microstructure for the material of the walls 102 that has a unique bimodal open porosity.
  • the microstructure of the material of the walls 102 (formed by the interconnected network 120 of the porous ceramic beads 122) has a total porosity (that is, relative to a total volume of the microstructure/walls) that comprises an intrabead porosity defined by the porosity of the porous structure 124 of the beads 122, and an interbead porosity, defined by the interstices 128 in the interconnected network 120 between the beads 122.
  • the intrabead porosity formed within the material of the beads, has an intrabead median pore size that is a fraction of the median particle size of the beads, while the interbead porosity, formed in the spaces between beads, has a relatively larger interbead median pore size (e.g., multiple times larger than the intrabead median pore size), which can approach the median particle size of the beads.
  • the aforementioned bimodal porosity has both intrabead and interbead pore size distributions, which differ from each other in that the pore sizes of the intrabead porosity are, on average, smaller than the pore sizes of the interbead pore sizes.
  • an intrabead median pore size of the intrabead pore size distribution is less than an interbead median pore size of the interbead pore size distribution.
  • FIG. 11 shows a flowchart of a method 200 for forming porous spheroidal cordierite beads (e.g., the beads 122) and a method 300 for manufacturing a honeycomb body (e.g., the honeycomb body 100) comprising a sintered network (e.g., the network 120) of the porous spheroidal cordierite beads.
  • a slurry mixture is formed of ceramic-forming raw material ingredients (e.g., in accordance to any of the Examples S1-S20).
  • the slurry mixture is spheroidized into green agglomerates (e.g., the green agglomerates 130).
  • the spheroidizing is performed by spraydrying. In some embodiments, the spheroidizing is performed by a rotary evaporation process. Other processes can be used, such as dry powderization, freeze drying, laser melting, melt spinning, or liquid jetting.
  • the green agglomerates can be at least partially dried as part of the spheroidizing process or following the spheroidizing process.
  • the green agglomerates are fired at conditions (times and temperatures) sufficient to convert the green agglomerates into porous cordierite beads (e.g., the beads 122).
  • porous cordierite beads e.g., resulting from the method 200, can be used as the primary inorganic material in a batch mixture (e.g., the batch mixture 110).
  • the batch mixture can comprise other ingredients such as an organic binder, inorganic binder materials (e.g., reactive cordierite-forming materials), pore formers (e.g., starch, graphite, etc.), oil or other lubricants, and a liquid carrier such as water.
  • the batch mixture is shaped (e.g., extruded via the honeycomb extrusion die 18), into a green honeycomb body (e.g., the green honeycomb body 100G).
  • the green honeycomb body is converted into a ceramic honeycomb body (e.g., the honeycomb body 100) by firing under conditions (time and temperature) sufficient to sinter the porous cordierite beads together and/or react and/or sinter any additional reactive inorganic binder materials in the batch mixture.
  • Additional steps such as drying and cutting may be performed before firing. Since the cordierite beads have already been reacted to form cordierite and any other selected ceramic phases, the firing temperature and/or firing duration at step 306 can be significantly reduced in comparison to honeycomb bodies that are formed from reactive precursor materials. As described herein, since the cordierite beads have already been reacted, the beads have sufficient strength to survive the honeycomb body manufacturing processes, e.g., mixing in an extruder and extrusion through a honeycomb extrusion die, without losing the spheroidal shape.
  • the beads will largely retain their size and shape during firing of the honeycomb body in step 306, thereby creating a microstructure for the honeycomb bodies that comprises an interconnected network of porous ceramic beads sintered together (e.g., the interconnected network 120).
  • channels e.g., the channels 104 of the ceramic honeycomb body can be plugged to form a plugged honeycomb body (e.g., the plugged honeycomb body 101).
  • plugged honeycomb bodies can be used as a particulate, or wall flow, filter.
  • a catalytic material can be deposited into and/or onto the porous walls (e.g., the walls 102) of the ceramic honeycomb body, e.g., by washcoating or other process.
  • the honeycomb body is both plugged and loaded with a catalytic material.
  • Aqueous-based agglomerate slurry mixtures comprising cordierite- precursor materials stabilized by small levels of organic binder and dispersant were used as feedstock in spraydrying processes.
  • Table 5 illustrates various examples of green agglomerates that were manufactured at different solid loadings using the slurry mixtures of Tables 1-4.
  • the raw materials were slowly added under mixing to the water, using a high power turbomixer (rotostator).
  • Raw materials were aspirated directly into the slurry tank under the water level to avoid raw material particle clustering in the slurry.
  • the binder and dispersant were then added.
  • Examples A1-10, A1-15, and A1-21 were made from the same slurry mixture (S1) at different solid loadings (10 vol%, 15 vol%, and 21 vol%, respectively). Examples A1-10, A1-15, and A1-21 may be referred to herein collectively as “Examples A1”. Similar to the different solid loadings for Examples A1 , the solid loadings for green agglomerates formed from any other slurry mixture, e.g., the slurry mixtures A2-A20, can differ from those given in Table 5. Furthermore, the solids loading depicted in Table 5 are intended as estimates, which may vary, e.g., by up to 0.5% volume when the slurry mixtures are actually made. In some embodiments, the solid loading in a spray dried slurry mixture is from about 8% by volume to about 35% by volume, such as from 10% volume to 30% volume.
  • a medium scale industrial spray dryer with a 2-fluid fountain nozzle or rotary atomizer was used for spraydrying the different combinations of slurry mixture and solid loading of Table 5 to form the green agglomerates. Rates of 6 kg/h to 20 kg/h were used.
  • Spraydryer settings for forming the green agglomerates included an inlet temperature of 200°C, cyclone temperature of 98°C, an inlet air velocity corresponding to a velocity head loss of 330 - 360 inches H 2 O (8382 mm H 2 O to 9144 mm H 2 O), and cyclone air velocity corresponding to a head loss of about 5 inches H 2 O (127 mm H 2 O).
  • Table 6 includes values for d10, d50, and d90, along with calculated values for (d90-10)/d50 (i.e., which may be referred to as “d breadth ” or the “breadth” of the corresponding particle size distribution) and d50-d10/d50 (i.e., which may be referred to herein as “df” or “dfactor”).
  • dlO refers to the particle size at which 10% of particles in the distribution are smaller (90% are larger)
  • d50 refers to the median particle size (50% of the particles are larger, 50% are smaller)
  • d90 refers to the particle size at which 90% of the particles in the distribution are smaller (10% are larger).
  • Capturing particles at both chamber and cyclone outlets of the spray dryer facilitated the ability to select or engineer the particle size distribution of the agglomerates and/or beads made from the agglomerates, as desired.
  • the cyclone collection point captured a smaller sized fraction of particles
  • the chamber captured a larger sized fraction of particles.
  • Further engineering of the particle size distribution can be accomplished by sorting or sieving the particles (e.g., the green agglomerates or fired beads) by removing the coarse (large) and/or fine (small) tail of the particle size distribution. In this way, narrow particle size distributions can be obtained for the green agglomerates (and resulting ceramic beads after firing).
  • a powder of green agglomerates is formed (e.g., by sorting and/or sieving) such that the median particle size (d50) of the green agglomerates in the powder ranges from about 10 ⁇ m to 80 ⁇ m, about 15 ⁇ m to 60 ⁇ m, or even about 20 ⁇ m to 50 ⁇ m.
  • the breadth (given by (d90- dl0)/d50) of the particle size distribution of the green agglomerates 130 is less than 1.5, less than 1.0, less than 0.9, or even less than 0.8.
  • the dfactor (given by (d50-dl0)/d50) of the particle size distribution of the green agglomerates is less than 0.5, less than 0.4, or even less than 0.3. Additionally or alternatively, air-classification, sieving or other processes can be used to remove one or more particle size ranges from a resulting particle size distribution to tailor the particle size distribution.
  • FIGS. 12A-12H shows representative examples of green spraydried agglomerates Al, A2, A8, A9, A10, Al l, A12, and A13 of Table 6 as taken from the chamber (not cyclone) of the spray dryer. More particularly, FIGS. 12A-12H show a surface SEM image and a polished cross- sectional SEM image for each of these green agglomerate examples. For the observation of polished sections, the powder was infiltrated with epoxy, sliced and polished.
  • green agglomerate example A2 evidences the relationship between high amounts of very fine raw material ingredients and the thickness of the green shell structure 132, as green agglomerate example A2 used a comparably large amount of very fine ingredients (e.g., silica soot having a median particle size of approximately 0.5 ⁇ m and hydrated alumina having a median particle size of approximately 0.1 ⁇ m per Table 2), which resulted in the thickest and most prominent green shell.
  • very fine ingredients e.g., silica soot having a median particle size of approximately 0.5 ⁇ m and hydrated alumina having a median particle size of approximately 0.1 ⁇ m per Table 2
  • the green agglomerate powders were converted in a firing process into cordierite bead powders.
  • the green agglomerate powders were fired in a variety of ways, including on alumina trays or setters, in batch furnaces, and/or in rotary calciners.
  • the particular firing equi ⁇ ment did not appear to significantly affect the resulting cordierite beads, although rotary calcining did assist in preventing sticking (sintering) of some Examples.
  • green agglomerate Examples A1, A2, A3, A4, A17, and A20 could all be converted by firing on trays and did not show significant sticking of the green agglomerates to each other or to the tray. Powders the other green agglomerate Examples benefited from rotary calcining to avoid sticking to the furnace ware.
  • Green agglomerate powder was also loaded into 11.5 inch by 19 inch by 5 inch dense alumina setter boxes, although any size setter box or tray can be used. Typical setter box loading for the tested examples was 4 kg - 7kg.
  • One or both of temperature and firing duration can be decreased to assist in the avoidance of sticking (sintering) of the spherical particles to each other or to the tray, thereby preserving the resulting cordierite beads as individual spheroidal particles.
  • the green agglomerates can be converted during high temperature firing through a number of decomposition, solid state reaction, and sintering steps into partially to fully reacted cordierite spheroidal particles (cordierite beads).
  • Porosity values were generated via MIP measurements taken of the fired cordierite beads using an Autopore IV 9500 porosimeter.
  • the powder of fired cordierite beads was filled into a test vessel, sealed, and then the mercury pressure was increased and infiltration measured.
  • the voids between the beads was first quickly filled at relatively low pressure, and then progressively smaller and smaller intrabead pores were next infiltrated.
  • increasingly smaller pore bottlenecks were overcome and the porosity beyond the bottleneck was infiltrated.
  • the bottleneck size reported in Tables 7A-7D as “intrabead pore size” was obtained. Accordingly, as only open porosity can be infiltrated and measured by MIP techniques, the porosity values in Tables 7A-7D all relate to open porosities.
  • a bimodal pore size distribution was obtained for each measured powder, having a first peak at a relatively small median pore size and a second peak at a relatively larger median pore size.
  • the median pore size may be referred to herein as the D50 (with a capital “D”, in contrast to the median particle size d50, which is designated with a lowercase “d”).
  • the second peak corresponding to the large “pore sizes” corresponded to the voids or openings between the beads in the powder bed packing in the sealed vessel (e.g., which resemble, and would become the interstices 128 defining the interbead porosity if the beads 122 were sintered together into the network 120), while the smaller first peak of pore sizes corresponded to the intrabead porosity in the beads.
  • Examples of similar bimodal pore size distributions having interbead and intrabead porosities that result from sintering the beads 122 into the network 120 are described in more detail below with respect to FIG. 17.
  • each bead is expected to deviate by some degree, so the reported intrabead material porosities can be considered herein on average for the beads (e.g., some beads within a sample, or within a honeycomb body manufactured utilizing the ceramic beads, can have intrabead porosities that are less than or more than the indicated intrabead material porosity).
  • the porosity and pore size values of Tables 7A-7D refer to the open accessible channels in the porosity.
  • the data was generally consistent with the microscopy observations (e.g., via analysis of SEM images).
  • the porosity of the material of the beads is at least 15%, at least 20% or even at least 25%, such as from about 15% to 60%, 15% to 50%, 15% to 40%, 20% to 60%, 20% to 50%, 20% to 40%, 25% to 60%, 25% to 50%, or 25% to 40%.
  • the top temperature and hold time of firing can be used as a surrogate to indicate whether the precursors in the green agglomerates have been sufficiently reacted into the cordierite beads.
  • the cordierite beads resulting from firing green agglomerates at a temperature of at least 1300°C for a time of at least 8 hours will be considered as sufficiently fully reacted.
  • the cordierite beads after being fired at a temperature of at least 1300°C for at least 8 hours, have an open intrabead porosity (relative to the volume of each bead) of at least 15%, at least 20% or even at least 25%, such as from about 15% to 60%, 15% to 50%, 15% to 40%, 20% to 60%, 20% to 50%, 20% to 40%, 25% to 60%, 25% to 50%, or 25% to 40%.
  • an open intrabead porosity relative to the volume of each bead
  • green agglomerate Examples A1, A2, A3, A4, A6, A8, A9, A10, All, A12, A13, A15, and A16 all exhibited high open porosities at sufficiently high levels of reaction in these embodiments.
  • the cordierite beads can also be assessed based on their stability against densification.
  • the cordierite beads are made from green agglomerates that result in ceramic beads having an open intrabead porosity of at least 20%, when fired at a top temperature of 1350°C for 8 hours, such as Examples A1, A3, A4, A6, A8, A10, All, A13, A15, and A16, which all exhibited relatively low tendency to densification at higher firing temperatures.
  • the cordierite beads are made from green agglomerates that result in ceramic beads having an open intrabead porosity of at least 20% when fired at a top temperature of at least 1400°C, such as Examples A1, A3, A6, A8, All, A15, and A16, which all exhibited particularly excellent resistance to densification at even the highest range of useable firing temperatures.
  • Examples A6, A15, and A16 were made from slurry mixtures that comprised starch, but otherwise resembled the slurry mixture Al) maintained consistently high porosities across the entire temperature range tested. That is, the porosity decreased more slowly (less densification) with increasing temperature than observed in other Examples (i.e., Examples A1, A6, A15, and A16 were less sensitive to higher temperature firing). In this way, Examples A1 , A6, A15, and A16 may be particularly well suited for embodiments, in which full reaction (e.g., via higher top temperatures and/or longer hold times) of the cordierite beads is desired.
  • Example 16 The rice starch in Examples A6 and A15 did not appear to have a significant impact on open pore channel size or open porosity (in comparison to Example Al which was made from a similar slurry mixture with no starch), as median open pore size was approximately 2 ⁇ m to 3 ⁇ m for the beads 122 made from Examples Al, A6, and A15.
  • Addition of corn starch in Example 16 did not appear to affect the overall open porosity, but, having a larger median particle size than rice starch, did substantially enlarge the median open pore size, e.g., to more than 5 micrometers.
  • the addition of corn starch, or other starches having relatively larger particle sizes may be advantageous in embodiments in which larger intrabead pore sizes are desired.
  • the beads 122 made from Example A16 showed a particularly broad pore size distribution with pore channels covering a size range from about 2 ⁇ m to 10 ⁇ m.
  • the addition of larger talc particles (e.g., in Example A7) compared to small talc based (e.g., Examples A2 and A4) also appeared to drive earlier and faster loss of the open porosity in the fired cordierite beads 122, thus forming only a small amount of open porosity around 1300°C (e.g., the green shell transforming into dense ceramic shell). Examples show that magnesium hydroxide in the precursor slurry was generally correlated to relatively higher open porosity in the fired beads.
  • magnesium hydroxide is included as the magnesia source in some embodiments, particularly where higher intrabead porosities are desired.
  • pure oxide precursor mixtures such as MgO, SiO 2 , AI 2 O 3 , or mixed oxides such as MgAl 2 O 4 , interact primarily via solid state diffusion and reaction at contact points between the beads with insignificant or without any glass or liquid formation and therefore react only at very high temperatures in comparison to other Examples, which lead these beads to sinter immediately under shrinkage with comparatively little or no develo ⁇ ment of intrabead porosity.
  • FIGS. 13A-13D show the microstructural evolution of representative examples of green agglomerates and resulting ceramic beads as a function of firing temperature. More particularly, FIGS. 13A-13D shows polished SEM cross-sectional views of green agglomerate particles (“GRN”) and resulting beads fired at temperatures of 1200°C, 1250°C, 1300°C, 1350°C, 1380°C, and 1410°C for 4h. For green particles containing bonded water in form of hydroxides, hydrated oxides, etc., all water was released below the temperature of 1200°C shown in FIGS. 13A-13D.
  • GNN green agglomerate particles
  • the formation of a ceramic shell assisted in preventing shrinkage of the beads during firing.
  • porosity within the beads instead of undergoing densification, porosity within the beads generally coarsened (enlarged) with increasing temperatures from between about 1200°C to about 1300°C or 1400°C, such that larger, interconnected pore channels initially developed over the temperature range shown for many of the examples in FIGS. 13A-13D.
  • Fired cordierite beads made from green agglomerates that comprised starch (e.g., beads from Examples A6, A15, and A16) initially showed the presence of relatively larger pores in the range of 1200°C to 1250°C. The fraction of those larger pores increased with the starch fraction, see beads made from Examples A6 and A15 for example.
  • the size of the pores can also be influenced by the type of the starch. For example, rice starch (Examples A6 and A15) has smaller particles than corn starch (Example A16), and thus produces beads with generally smaller pores during starch burn out.
  • porosity starts to decrease in some types of the particles, while it is preserved in others up to about 1400°C.
  • cordierite beads made from green agglomerate powder Example A1 significantly preserved high open porosity until 1410°C with only minor densification.
  • cordierite beads formed from green agglomerate powder example A2 which exhibited a thick outer layer of fine particles forming the green shell 132, described above, developed the hard ceramic shell 133 during firing, yielding only a very low level of open porosity.
  • beads formed from green agglomerate Example A2 began to significantly shrink, densify, and sinter together.
  • Beads formed from green agglomerate powder Example A6 (which comprises starch) had more porosity than the starch-free examples (e.g., Example Al), but also exhibited an earlier sintering onset that drove the formation of increasingly larger pores at or above 1350°C.
  • Porosity and pore size of beads made from green agglomerate Example Al 5 appeared significantly consistent with those made from Examples Al and A6 across the illustrated temperature range of FIGS. 13A-13B.
  • Beads made from green agglomerate powder example A16 exhibited a high open porosity with large pores due to presence of corn starch, with porosity and pore channels remaining significantly stable up to 1410°C.
  • the ceramic phases present in the fired powders were identified by X-ray diffraction (XRD).
  • XRD X-ray diffraction
  • a Bruker D4 diffraction system equipped with a multiple strip LynxEye high speed detector was utilized. It was generally found, regardless of green agglomerate Example used, that the amorphous (glassy) content decreased quickly during firing between 950°C and 1150°C, and then stabilized at around 10 wt% glass for firing at 1250°C and above with subsequent cooling.
  • In-situ XRD showed that the amorphous/glass phase can reach up to 50% at intermediate calcining steps for some compositions. The measured amount of glass in the calcined powders frequently depends on the cooling rate of the powders.
  • Table 8 provides example ceramic phase compositions that resulted for the beads produced at the two highest firing temperatures of Tables 7A-7D (1380°C and 1410°C). Blanks in Table 8 indicate that the data was incomplete or unavailable. Only phases of cordierite (with its polymorph indialite), sapphirine, and spinel are shown in Table 8. As indialite is polymorph of cordierite, any general reference to the amount of “cordierite” herein includes the sum of both the cordierite and indialite phases. Rietveld refinement was used for quantification of the phase contributions, which typically only included the crystalline phases (no glass). An estimate of the glass phase is provided based on a fit of the amorphous background, thus with an understanding that the estimates of glass levels may have a higher error bar than the crystalline phases.
  • Examples A18 and A19 were highly under-reacted after the firing conditions given in Tables 7A-7D and 8, leading to the failure to develop any significant porosity upon firing and high levels of cristobalite, quartz, alumina, spinel, and sapphirine.
  • some compositions may require very high temperatures and/or significantly longer hold times to form cordierite. For example, much longer firing times, e.g., up to 15h or even 20h could be required to complete reaction of the reactive ceramic precursors in Examples such as A18 and A19.
  • Example A2 Most clay, talc or clay-talc derived mixtures transformed readily into cordierite under the conditions of Tables 7A-7D and 8, thereby transforming into porous cordierite beads. Only a few Examples, see for Example A2, developed a porous structure that was not an open porosity (i.e., a closed porosity, which was not visible based on MIP data, but was identified from a combination of SEM and tomography data analysis).
  • Ceramic beads formed having high percentages of cordierite phase showed consistently higher open porosities at all tested temperatures.
  • the high-percentage cordierite composition beads were generally not as sensitive to firing temperature (i.e., generally exhibited a high resistance to densification even at higher temperatures), while the lower- cordierite beads were more highly sensitive to densification at higher temperatures.
  • green agglomerate powders that result in higher percentages of cordierite phase are advantageous in some embodiments to ensure that the beads can be fully reacted.
  • Fully reacted beads may be particularly advantageous to enable higher temperature firing of final ceramic honeycomb bodies 100 without densification of the beads during the final honeycomb body firing.
  • the beads 122 comprise at least 75 wt%, at least 80 wt%, or even at least 85 wt% cordierite (again, inclusive of the wt % indialite).
  • the crystalline phases (thus, excluding glass) comprise at least 90 wt% cordierite, or even at least 95 wt% cordierite.
  • Firing was also conducted for the green agglomerate powder examples at very slow heating rates (10°C/h to 20°C/h) and the resulting differential scanning calorimetry (DSC) results were analyzed.
  • DSC differential scanning calorimetry
  • binder/dispersant burn-out was observed at relatively low temperature (e.g., between about 250°C and 450°C).
  • the main mass release for most green agglomerate powders was observed at about 400°C. In the temperature range of about 400°C to about 1000°C, decomposition reactions of hydroxides and carbonates were observed, as water and/or CO2 were being released.
  • Hydrated raw materials include hydrated alumina, magnesium hydroxide, clay, and talc.
  • the bonded water is significantly or even fully preserved, so that the spray dried green agglomerate powders contain the hydrated compounds.
  • the decompositions of these components are observable as endothermic reactions. Decomposition of hydrated alumina was observed about 300°C, magnesium hydroxide at about 400°C, clay dehydration at about 520°C, and talc dehydration at about 920°C, although the water loss temperatures can be shifted due to batch interactions.
  • platy raw materials e.g., talc
  • develo ⁇ ment of intrabead porosity during firing it was found to be insufficient to merely have large, platy raw materials.
  • Use of overly large platy raw materials led in some cases to fired beads that were no longer spherical, and/or that fractured into segments (e.g., beads made from agglomerate Example A7, formed from a clay-silica-alumina-talc mixture that contained 15% of large talc, and beads made from agglomerate Example A12, formed from a clay and Mg(OH)2 mixture that also comprised large talc particles.
  • the maximum dimension of the platy raw materials is within at most 40%, at most 35%, at most 30%, or even at most 25% of the median particle size of the fired beads.
  • platy raw materials having a median particle size of at most about 10 ⁇ m were found to be suitable for beads in the range of about 30 ⁇ m to 40 ⁇ m in median particle size, but not for beads of smaller median bead (particle) size.
  • high levels of platy raw materials did not necessarily promote formation of intrabead porosity during firing, as some beads fired from green agglomerates comprising a high-talc slurry mixture (e.g., beads made from green agglomerate Examples A17 and A18) preserved a blocky shape and did not develop any intrabead porosity.
  • some beads fired from green agglomerates comprising a high-talc slurry mixture e.g., beads made from green agglomerate Examples A17 and A18
  • preserved a blocky shape and did not develop any intrabead porosity e.g., in general the use of magnesium hydroxide, and in particular high levels of magnesium hydroxide (e.g., as the only magnesia source) promoted formation of high open intrabead porosity.
  • Table 9 shows some representative firing conditions that were useful for fully reacting various green agglomerate powders, although other conditions are possible as described herein.
  • top temperatures of at least 1100°C, at least 1200°C, at least 1250°C, or at least 1300°C are suitable. In some embodiments, hold times between about 4 and 12 hours are suitable.
  • Table 10 shows values of d10, d50, d90, d90-d10, and (d90-d10)/d50 that were obtained for cordierite beads formed from various green agglomerate powders of Table 5 fired according to the conditions of Table 9. Multiple runs were made for some of the Examples to illustrate that there will be some variation in the properties of cordierite beads made from the same or similar green agglomerate powders under the same or similar firing conditions.
  • Green agglomerate powder Examples A1, A2, A3, A4, A6, and A17 successfully produced Example cordierite beads B1 , B2, B3, B4, B6, and B17, respectively, as porous cordierite beads having high open porosities.
  • Example cordierite beads B18, B19, and B20 produced respectively from green agglomerate powder Examples A18, A19, and A20 were all highly dense cordierite beads having low open porosity.
  • cordierite beads B1, B2, B6, and B17 had microstructures corresponding to those made from the same green agglomerate Example at the corresponding temperature in the evolution of Tables 7A-7D and FIGS. 13A-13D.
  • beads Bl which from Tables 7A-7D was formed by firing green agglomerate Example A1 at a top temperature of 1380°C
  • cordierite bead Example B1 exhibited large open porosity and narrow interconnected open pore channels (e.g., akin to representative beads 122A and/or 122B of FIGS. 9A and/or 9B), while cordierite beads B6, B15, and B16 exhibited large open, interconnected porosity and large interconnected open pore channels (e.g., akin to representative bead 122C of FIG. 9C).
  • Cordierite bead example B2 corresponding to a stage of evolution of green agglomerate powder Example A2 between 1350°C and 1380°C of FIG. 13B, exhibited a thick outer ceramic shell with high intrabead porosity, but low interconnectivity and low intrabead pore access (e.g., few or none of the openings 126).
  • the powders of fired cordierite beads made from green agglomerate powder Examples Al- A20 were characterized by SEM and image analysis for the sphericity.
  • the bead sphericity for the spray dried beads was determined to be greater than 0.9 on a scale ranging from 0 (infinitely long rods or plates) to 1 (perfect spheres), obtained by SEM image analysis as the aspect ratio between minimum and maximum bead dimensions.
  • Table 11 shows circularity and mean roundness values calculated for a representative sampling of cordierite beads made from green agglomerate Examples A1, A8, A10, A11, and A12, as indicated.
  • the spheroidal beads have a circularity of at least 0.9, at least 0.92, at least 0.94, at least 0.95, or even at least 0.96.
  • the spheroidal beads have a mean roundness of at least 0.8, at least 0.82, at least 0.84, at least 0.85, or even at least 0.86.
  • the ceramic beads 122 disclosed herein can have high internal surface areas. High internal surface area provides particular advantages in some applications for the honeycomb bodies 100, such as when the honeycomb body is arranged as a particulate filter or catalyst support. As described herein, the high surface area may be particularly advantageous when the beads 122, having high internal surface area and high open intrabead porosity, are paired with the interbead porosity created by the interstices 128 when the beads 122 are sintered into the network 120.
  • Table 12B The surface areas in Table 12B were derived from single point or Brunauer-Emmett-Teller (BET) methodologies, as indicated. The internal surface area was also evaluated in Table 12A as to whether it was contributed by open or closed pore structures. Table 12A lists the ratio of total internal to external bead surface area and also the ratio for open internal surface area to external bead surface area. The estimated extra surface area calculated in Table 12B was determined by subtracting the estimated outer surface area (thus corresponding to the approximate total surface area of a dense bead) from the BET surface area of the porous beads (which have both an outer surface area and the internal surface area attributable to the open porosity).
  • BET Brunauer-Emmett-Teller
  • the outer surface area of a bead can be estimated by approximating the bead as sphere. Since smaller beads have less volume in which to form surface area, the estimated extra surface area was also normalized to the size of the beads by dividing the extra surface area by the median agglomerate size for each bead in Table 12B.
  • Table 12A Surface Areas of Bead Powder Sample By Tomography
  • Table 12B Surface Areas of Ceramic Bead Powder Sample By BET
  • the ratio of the open intrabead surface area to outer surface area of the porous ceramic beads is at least 5 : 1 , at least 6: 1 , at least 7: 1 , at least 8 : 1 , at least 9: 1 , or even at least 9.5:1, including any range including these ratios as end points, such as from 5:1 to 10:1, from 5:1 to 9.5:1, from 5:1 to 9:1, from 6:1 to 10:1, from 6:1 to 9.5:1, from 6:1 to 9:1, from 7:1 to 10:1, from 7:1 to 9.5:1, from 7:1 to 9:1, from 8:1 to 10:1, from 8:1 to 9.5:1, from 8:1 to 9:1, from 9:1 to 10:1, from 9:1 to 9.5:1, or even from 9.5:1 to 10:1.
  • the closed porosity of the porous ceramic beads is at most 5%, at most 4%, at most 3%, or even at most 2.5%, including ranges with these values as end points, such as from 0% to 5%, from 0% to 4%, from 0% to 3%, or from 0% to 2.5%. In some embodiments, the
  • beads made from slurry mixture Examples SI and S8 have very high relative internal to external surface areas, attributable to the relatively small median pore sizes and high open porosities. Due to the small amount of closed porosity in the beads made from slurry mixture Examples SI and S8, the calculated surface area ratios are significantly unchanged for high-open porosity beads, such as those made from green agglomerate Examples A1 and A8, when the surface area due to closed porosity is excluded. In comparison, the beads made from green agglomerate Example A2 (slurry mixture S2) had a relatively high closed porosity (e.g., due to the formation of the ceramic shell 133 as described herein) and large median pore size.
  • the analyzed sample made from slurry mixture S2 shows only internal surface six times as much as the external bead surface area, which is further reduced to a ratio of four times when closed porosity is excluded.
  • the internal surface area decreases as the number of pores decreases and the size of the pores increases, while the open internal surface area decreases with respect to increasing closed porosity.
  • the BET can be estimated from the model by is the density of the ceramic material.
  • Table 13 summarizes model calculations, showing the effect of changing input values for r, %P, and median pore size (D50) on the internal/external surface area ratio and estimated BET value. For Table 13 it is assumed that p is 2.52 g/cm 3 and that the pores/channels extend through the entire bead, thus assuming L on average is equal to r.
  • the slurry mixtures (e.g., Examples S1-S20) were rapidly dried by rotary evaporating. Although somewhat more irregular (e.g., oblong, oblate, tear shaped, etc.), spheroidal shaped green agglomerate particles generally similar to spraydried agglomerate Examples A1-A20 were obtained by rotary evaporation of solvent from the slurry mixtures, sieving the dried powder to a target particle size, and firing the sieved powder at top temperatures above 1300°C to react the precursor raw materials into cordierite.
  • This alternate process also provided similar microstructure to the spraydried powder examples with advantageously high open porosity and pore size distribution as described herein.
  • FIG. 14 shows the microstructure of three cordierite beads made by firing: (i) Example A8 made from slurry mixture S8 using the spray dry process described above; (ii) Example RV1 that was made from slurry mixture S8 using the rotary-evaporation process; and (iii) Example RV2 that was also made from slurry mixture S8 using the rotary-evaporation process, but further comprising a pore former addition of 20 vol% corn starch.
  • green agglomerates with similar pore structure can be made with the rotary evaporation technique.
  • RV2 shows that addition of pore former, such as corn starch, can create comparatively larger pores, such as in the 5-10 ⁇ m range for corn starch. In other embodiments, smaller and larger starch particles can be used to form smaller and larger pores, respectively.
  • Porosity and pore size of the cordierite beads of FIG. 14 were determined by mercury intrusion porosimetry. As shown in Table 14, there was significant similarity in the porosity and pore size values for green agglomerate Example A8 derived by spray drying and for Example RV 1 derived by the alternative rotary-evaporation process, thereby indicating that rotary-evaporation is a suitable alternative process to spraydrying.
  • the various cordierite beads were included as ingredients in batch mixtures (e.g., the batch mixtures 110) that were extruded to form green honeycomb bodies (e.g., the green honeycomb bodies 100G).
  • the green honeycomb bodies were cut to length, dried, and then fired to form ceramic honeycomb bodies (e.g., the honeycomb bodies 100).
  • the honeycomb bodies can be fired at temperatures lower than or similar to those used to fire the cordierite beads, such as in the range of approximately 1350°C to 1410°C.
  • the batch mixture before addition of a liquid carrier and with respect to a total weight of inorganic components in the batch, comprises at least 50 wt%, at least 55 wt%, at least 60 wt%, at least 70 wt%, at least at least 75 wt%, at least 80 wt%, at least 85 wt%, or even at least 90 wt% of the porous ceramic beads, including ranges including these values as endpoints, such as from 55 wt% to 95 wt%, from 55 wt% to 90 wt%, from 55 wt% to 85 wt%, from 55 wt% to 80 wt%, from 60 wt% to 95 wt%, from 60 wt% to 90 wt%, from 60 wt% to 85 wt%, from 60 wt% to 80 wt%, from 70 wt% to 95 wt%, from 70 wt% to 90 wt%, from 70 wt%, from 70
  • An inorganic binder such as one or more ceramic precursor materials or shear binder agglomerates as described herein, can be added relative to the porous ceramic beads in an amount to bring the total of these components to 100 wt%, such as in an amount of at least 5 wt%, at least 10 wt%, at least 15 wt%, at least 20 wt%, or at least 25 wt%, such as from 5 wt% to 25 wt%, from 5 wt% to 20 wt%, from 5 wt% to 15 wt%, from 5 wt% to 10 wt%, from 10 wt% to 25 wt%, from 10 wt% to 20 wt%, from 10 wt% to 15 wt%, from 15 wt% to 25 wt%, or from 20 wt% to 25 wt%.
  • Pore formers can be added as a super addition in any suitable amount, such as at least 10 wt%, at least 20 wt%, at least 30 wt%, or at least 40 wt% super addition, including any range with these values as end points.
  • Extrusion aids such as oil
  • An organic binder such as methylcellulose
  • the heating ramp rate is at least 50°C/h, at least 100°C/h, at least 150°C/h, at least 200°C/h, or even at least 300°C/h, including ranges having these values as endpoints, such as from 150°C/h to 350°C/h, from 200°C/h to 350°C/h, from 250°C/h to 350°C/h, from 300°C/h to 350°C/h, from 150°C/h to 300°C/h, from 200°C/h to 300°C/h, or from 200°C/h to 250°C/h.
  • honeycomb bodies were extruded as 1” or 2” diameter parts by a ram extruder, or as a 2” diameter part by a twin screw extruder, and dried in a microwave dryer followed by a hot air drying oven, as applicable.
  • the paste was first thoroughly mixed, such as by being passed through the twin screw with screens and a large open die and/or several times through a spaghetti die prior to pressing it through the ram extruder.
  • twin screw extrusions the batch mixture paste was directly filled into the feeder for the extruder barrel. In general, a screen package was used to protect the extrusion die and provide homogeneous batch paste flow.
  • the fired cordierite beads were sieved, e.g., via a 270 or 325 size mesh in an automated sieve, as applicable, to remove large size agglomerates, thereby avoiding clogging of the extrusion die slots during extrusion.
  • the extruded green honeycomb bodies were fired at temperatures between 1340°C and 1420°C for four to six hours. At these times and temperatures, the cordierite beads were generally fully reacted before addition to the batch mixtures, which kept firing times for the honeycomb bodies short as no further solid state reactive transformation was needed in the beads (only reaction of any reactive inorganic binder materials added to the batch mixture and/or sintering between the beads). Firing was accomplished in air without specific oxygen control. Heating rates were typically between 100°C/h and 300°C/h (although slower heating rates and/or holds were employed between about 400°C and 1000°C during organic burn out).
  • the median particle size of the cordierite beads in the batch mixture was greater than 15% or even 20% of the width of the die, with d90 values for the cordierite beads being from 20% to 40% of the slot width.
  • the width of the slot in a 300/8 die may be approximately 200 ⁇ m, with median bead (particle) size (d50) values for the cordierite beads being upwards of 50 ⁇ m, and the d90 values of the cordierite beads exceeding 50 ⁇ m, 60 ⁇ m, or even 70 ⁇ m.
  • Corn starch, rice starch, pea starch, and graphite were used as pore formers, although other pore formers can also be used to create porosity.
  • Methylcellulose performed successfully as an organic binder for enabling extrudability and maintaining the shape of the green honeycomb bodies.
  • Tables 15A-15E list a first set of batch mixtures and extrusion conditions that were used to successfully form (extrude) honeycomb bodies.
  • the green extruded honeycomb bodies were converted into ceramic honeycomb bodies by subsequent firing steps.
  • the honeycomb bodies comprised intersecting walls having with about 13-15 mil (“300/13”, “300/14” and/or “300/15” configuration) or 8 mil (“300/8 configuration”) nominal wall thickness, as indicated, although other wall thickness can be used.
  • the honeycomb bodies had approximately 300 cells per square inch (300 cpsi), although other cpsi values, such as from 200-1000 cpsi can alternatively be used.
  • the batch mixtures of the Examples of Tables 15A-15E comprised reacted cordierite beads, e.g., fully-reacted cordierite beads, having mean bead (particle) sizes ranging from 18 ⁇ m to 50 ⁇ m.
  • inorganic reactive binder materials e.g., talc, alumina, silica, etc.
  • shear binder agglomerates that contained inorganic binder materials were used in addition to and/or in lieu of separate inorganic binder materials.
  • shear binder agglomerates or simply “shear binders” refers to green spheroidal particles that were formed from slurry mixtures described herein (i.e., in accordance with slurry mixture Examples S1-S20), and in significantly the same manner as the green agglomerates 130 described herein, although higher solid loadings can be used during spraydrying or other spheroidizing processes. That is, the shear binder agglomerates referred to herein are substantially the same as the disclosed green agglomerates (thus, for example, the green agglomerates A1-A20, or others, can be used as shear binder agglomerates).
  • the shear binders are made from the same slurry mixtures as the green agglomerate samples described herein, but optionally at higher solid loadings.
  • solid loadings of between 15-50 vol% can be used to form shear binder agglomerates useful as an inorganic-type binder ingredient during manufacture of honeycomb bodies (in comparison to about 10-30 vol% solid loading used for the green agglomerates).
  • the shear binder agglomerates aid in sintering of the beads by providing additional inorganic material concentrated at, or extending between, contact points with the beads due to shearing (or deformation) of the shear binder agglomerates during mixing with the beads.
  • the total weight of the shear binder agglomerates is considered herein as part of the total weight of inorganics in the batch mixture. Accordingly, in many of the Examples in which shear binder agglomerates are employed, the weight of the beads and the weight of the shear binder agglomerates sum to 100% as the total weight of inorganics in the batch mixture.
  • shear binder agglomerates are indicated for the relevant Examples in Tables 15A-15E. Same or different shear binder compositions can be used as the calcined cordierite beads for any given honeycomb extrusion. Successful combinations were made from fired cordierite beads obtained without any Na-addition, but combined with shear binder green agglomerates that did contain a small amount of Na (e.g., less than 2 wt% with respect to the total weight of inorganics in the shear binder agglomerates). Such combinations produced comparatively low CTE and enabled the use of comparatively low honeycomb firing temperatures and/or shorter hold times, such as via glass formation at pore contact points.
  • the required water calls were much higher for the batch mixtures comprising cordierite beads having high open porosity (e.g., in comparison to traditional reactive raw material batches or batch mixtures having dense or closed-porosity beads).
  • the water call was greater than 30 wt%, greater than 40 wt%, or even greater than 50 wt%, as super addition with respect to the total weight of inorganics.
  • the high water amounts are believed to be necessary to fill the intrabead porosity of the beads, which acts with high capillarity force and pulls water into the intrabead pore structures of the beads.
  • the required water level for extrusion generally increased with increasing open intrabead porosity of the cordierite beads and with the median particle size of the beads.
  • friction in the batch and wall drag of the extrusion paste along the die wall were very low, so high amounts of oils or other lubricants were of limited benefit, particularly for dies having wider slots (e.g., the 300/13 and 300/14 dies tested).
  • FIGS. 15A-15D show microstructures of fired honeycomb bodies showing the interbead and intrabead porosities described herein. More particularly, FIG. 15 A and 15B respectively show surface views of the surface of a wall (the wall 102) at magnifications of 500x and 2000x for honeycomb body Example H9. FIGS. 15C and 15D respectively show a wall cross section and view of the wall surface for a honeycomb body produced in accordance with Example H10.
  • the interbead pore sizes size of the interstices 128 between the beads 122) were in the range of 10-20 ⁇ m and the intrabead pore sizes (pore size in the beads) were in the range of about 1-5 ⁇ m.
  • Honeycomb bodies were fired at top temperatures ranging between 1330°C and 1410°C, corresponding to the highest top temperatures used to form the cordierite beads as described above. In general, temperatures of less than 1350°C were too low to enable sufficient cordierite formation within the inorganic components of the shear-binders in some embodiment, in particular shear binder agglomerates made from slurry mixture Example S2.
  • sodium e.g., in the form of sodium stearate
  • the inclusion of sodium was found to be useful to enable lower reaction temperatures than Na- free batch mixtures (e.g., temperatures less than 1350°C), but can also lead to insufficient cordierite formation and correspondingly fragile ware if the sodium is not present in a sufficient amount (e.g., at least 0.2%, at least 0.5%, or at least 1.0%).
  • Ceramic honeycomb bodies were formed by firing the green bodies obtained by extruding the indicated batch mixtures of Tables 15A-15E at 1320°C to 1415°C for 4-20 hours.
  • Tables 16A-16D provide phase compositions of honeycomb bodies made by firing the green honeycomb bodies from several of the Examples of Tables 15A-15E under the indicated firing conditions, as obtained by XRD analysis with Rietveld analysis for the material. The level of glass was derived for some Examples by a semiquantitative estimation. Blank entries for ceramic phases in the Tables indicate that the presence of that phase was not found, while blank entries for glass instead indicates that the Example was not analyzed for its glass content.
  • the crystalline phases comprised at least 90 wt% cordierite, or even at least 95 wt% cordierite.
  • the firing of some honeycomb bodies utilized a “spike”, in which the temperature was initially temporarily raised to a “spike” temperature above the top soak temperature, and then, after a period of at most about 30 minutes, dropped to and held at the top soak temperature.
  • the firing conditions “1380°C / 4h - 1410°C Spike” indicates that the temperature was initially raised to 1410°C (the spike) and then dropped to and held at 1380°C for 4 hours.
  • the honeycomb body comprises at least 80 wt%, at least 85 wt%, or even at least 90 wt% of a cordierite phase (inclusive of both cordierite and indialite), such as from 80 wt% to 95 wt%, from 85 wt% to 95 wt%, 90 wt% to 95 wt%, 80 wt% to 90 wt%, 85 wt% to 90 wt%, or 85 wt% to 94 wt%.
  • the honeycomb body comprises less than 15 wt% glass, such as from 4 wt% to 11 wt%.
  • the honeycomb body comprises less than 3 wt%, less than 2.5 wt%, less than 2 wt%, or even less than 1 wt% of secondary ceramic phases.
  • the fully fired honeycombs did not show any significant amount of cristobalite (e.g., less than 0.1 wt%) and comparatively lower levels of secondary phases such as spinel and sapphirine than the fired cordierite beads themselves (e.g., as shown in Table 8). Glass levels in the honeycombs were typically found to be around 8-11 wt%, but it is again noted that the level of glass was only semi- quantitatively determined from background adjustment in the Rietveld analysis and therefore prone to some degree of error. However, inspection by SEM experimentally confirmed generally low levels of glass present in various honeycomb body Examples, e.g., less than 15 wt%, less than 10 wt% or even less than 5 wt%.
  • Tables 17A-17D and 18A-18D respectively provide various porosity and thermomechanical properties obtained for various ones of the honeycomb body Examples of Table 15A-15E at the indicated firing conditions.
  • Tables 18A-18D reports both axial and tangential (tang) CTE values from room temperature (RT) to both 800°C and 1000°C, as well as both transverse and axial i-ratio values for some of the analyzed honeycomb bodies.
  • the total porosity (sum of both interbead porosity and intrabead porosity) of the material of the walls of the ceramic honeycomb bodies materials was greater than 50%, ranging from 55% to 65%.
  • the overall median pore size (including both interbead pore size and intrabead pore size) ranged from about 6 ⁇ m to about 12 ⁇ m.
  • the porosity of the material of the walls of the ceramic honeycomb bodies was bimodal with an interbead porosity in the range of about 45% - 60%, and interbead median pore size (size of interstices 128) in a range from about 7 ⁇ m to 13.5 ⁇ m.
  • the intrabead porosity of the material of the walls of the ceramic honeycomb bodies was in a range from about 10% to 15%, with an intrabead median pore size ranging from about 1.8 ⁇ m to 2.6 ⁇ m.
  • the breadth of the interbead porosity was very narrow with d90-dl0 ranging from about 12 ⁇ m to 19 ⁇ m.
  • the interbead pore size was at least partially dependent on the median bead size of the spheroidal cordierite beads used in the batch mixture (with larger beads producing larger interbead median pore sizes).
  • the breadth of the interbead porosity was seen to be at least partially dependent on the breadth of spheroidal bead size distribution (with a narrower breadth of the size distribution of the cordierite beads used in the batch mixture resulting in a narrow breadth of the size distribution of the interbead pores).
  • a wide breadth was purposely introduced for the cordierite beads used in honeycomb body Example H6 by mixing beads of two different median bead sizes, which resulted in a wider breadth of the interbead pores for the resulting ceramic honeycomb body.
  • CTE coefficients of thermal expansion
  • the CTE and other thermomechanical properties of the ceramic honeycomb bodies were very isotropic, as indicated by direct measurements of axial and tangential CTE or the i-ratios of the materials.
  • the i-ratios in both the axial and tangential direction were very similar for the material of all honeycomb bodies that were made from the batch mixtures comprising porous spheroidal cordierite beads.
  • the ratio of the two values typically ranges around 0.99 and 1.04.
  • the ratio of these two i-ratio values for a cordierite honeycomb body made from a traditional reactive batch may be on the order of 1.5 or greater.
  • the lack of anisotropy is believed to result from the spheroidal shape of the beads, which do not undergo alignment during extrusion in comparison to platy, rod-like, or other non- spheroidal particles having greater aspect ratios, which are pushed into alignment with the flow direction through slots of the honeycomb extrusion die.
  • the intrabead median pore size of the material of the ceramic article is less than 5 ⁇ m, less than 4 ⁇ m, less than 3.5 ⁇ m, less than 3 ⁇ m, less than 2.5 ⁇ m, or even less than 2 ⁇ m, including ranges having these values as endpoints, such as from 1.5 ⁇ m to 5 ⁇ m, preferably from 1.5 ⁇ m to 4 ⁇ m, from 1.5 ⁇ m to 3.5 ⁇ m, from 1.5 ⁇ m to 3, from 1.5 ⁇ m to 2.5 ⁇ m, or even from 1.5 ⁇ m to 2 ⁇ m.
  • the interbead median pore size of the material of the ceramic article is at least 6 ⁇ m, at least 7 ⁇ m, at least 8 ⁇ m, at most at most 20 ⁇ m, at most 19 ⁇ m, or at most 18 ⁇ m, including ranges having these values as endpoints, such as from 6 ⁇ m to 20 ⁇ m, from 6 ⁇ m to 19 ⁇ m, from 6 ⁇ m to 18 ⁇ m, from 7 ⁇ m to 20 ⁇ m, from 7 ⁇ m to 19 ⁇ m, from 7 ⁇ m to 18 ⁇ m, from 8 ⁇ m to 20 ⁇ m, from 8 ⁇ m to 19 ⁇ m, or from 8 ⁇ m to 18 ⁇ m.
  • the interbead median pore size is proportional to the size of the beads used to make the ceramic article, and therefore can be influenced by selecting (e.g., via sieving) the particle size distribution of the beads used.
  • the median pore size of the material of the ceramic article is at least 5 ⁇ m, at least 6 ⁇ m, at least 7 ⁇ m, at most 18 ⁇ m, at most 17 ⁇ m, or at most 16 ⁇ m, including ranges having these values as endpoints, such as from 5 ⁇ m to 18 ⁇ m, from 5 ⁇ m to 17 ⁇ m, from 5 ⁇ m to 16 ⁇ m, from 6 ⁇ m to 18 ⁇ m, from 6 ⁇ m to 17 ⁇ m, from 6 ⁇ m to 16 ⁇ m, from 7 ⁇ m to 18 ⁇ m, from 7 ⁇ m to 17 ⁇ m, or from 7 ⁇ m to 16 ⁇ m.
  • the intrabead porosity (as measured by MIP) relative to the total volume of the interconnected bead network is at least 10%, at least 12%, at least 15%, at least 18%, at least 20%, or even at least 25% including ranges having these values as endpoints, such as from 10% to 30%, from 10% to 25%, from 10% to 20%, from 10% to 15%, from 12% to 30%, from 12% to 25%, from 12% to 20%, from 15% to 30%, from 15% to 25%, from 15% to 20%, from 18% to 30%, from 18% to 25%, from 20% to 30%, or even from 25% to 35%.
  • the intrabead porosity can alternatively be considered with respect to the individual volume of the beads themselves.
  • the intrabead porosity (as measured by MIP) relative to the individual volume of the beads is at least 9%, at least 10%, at least 12%, preferably at least 15%, at least 18%, or even more preferably at least 20%, at least 25%, or even at least 30%, including ranges having these values as endpoints, such as from 9% to 42%, from 9% to 35%, from 9% to 30%, from 9% to 25%, from 9% to 20%, from 9% to 15%, from 10% to 35%, from 10% to 30%, from 10% to 25%, from 10% to 20%, from 10% to 15%, from 12% to 35%, from 12% to 30%, from 12% to 25%, from 12% to 20%, more preferably from 15% to 35%, from 15% to 30%, from 15% to 25%,
  • the median particle size (d50) of the beads can be affected, influenced, or even set, by removing one or more size fractions from the bead powder.
  • removal of one or more bead fractions is accomplished by sieving. For example, removing a larger size fraction can be implemented to lower the median bead size, while removing a smaller size fraction can be implemented to increase the median bead size.

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Abstract

L'invention concerne une poudre céramique, un mélange vitrifiable comprenant la poudre céramique, un article vert formé à partir du mélange vitrifiable, un procédé de fabrication d'une poudre céramique et un procédé de fabrication d'un article céramique. La poudre céramique comprend une pluralité de billes de céramique poreuses. Les billes de céramique ont une taille de particule médiane d'au moins 20 µm, une taille de pore médiane inférieure à 4 µm et une porosité ouverte d'au moins 12 %.
PCT/US2021/043648 2020-07-31 2021-07-29 Billes de cordiérite à porosité ouverte et articles en céramique fabriqués à partir de celles-ci WO2022026671A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014189817A1 (fr) * 2013-05-20 2014-11-27 Corning Incorporated Article en céramique poreux et procédé de fabrication associé
EP3202477A1 (fr) * 2014-09-30 2017-08-09 Hitachi Metals, Ltd. Filtre à nid d'abeilles en céramique et son procédé de fabrication
EP3347328A1 (fr) * 2015-09-11 2018-07-18 Saint-Gobain Ceramics&Plastics, Inc. Procédé de formation de particules en céramique poreuse
WO2019089735A1 (fr) * 2017-10-31 2019-05-09 Corning Incorporated Compositions de mélanges comprenant des particules inorganiques ayant préalablement réagi et procédés de fabrication de corps crus à partir de celles-ci
CN107266097B (zh) * 2017-07-28 2019-08-20 武汉科技大学 一种轻量莫来石耐火材料及其制备方法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014189817A1 (fr) * 2013-05-20 2014-11-27 Corning Incorporated Article en céramique poreux et procédé de fabrication associé
EP3202477A1 (fr) * 2014-09-30 2017-08-09 Hitachi Metals, Ltd. Filtre à nid d'abeilles en céramique et son procédé de fabrication
EP3347328A1 (fr) * 2015-09-11 2018-07-18 Saint-Gobain Ceramics&Plastics, Inc. Procédé de formation de particules en céramique poreuse
CN107266097B (zh) * 2017-07-28 2019-08-20 武汉科技大学 一种轻量莫来石耐火材料及其制备方法
WO2019089735A1 (fr) * 2017-10-31 2019-05-09 Corning Incorporated Compositions de mélanges comprenant des particules inorganiques ayant préalablement réagi et procédés de fabrication de corps crus à partir de celles-ci

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