WO2021231269A1 - Corps en nid d'abeilles conducteurs ayant une capacité de chauffage par résistance et leurs procédés de fabrication - Google Patents

Corps en nid d'abeilles conducteurs ayant une capacité de chauffage par résistance et leurs procédés de fabrication Download PDF

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Publication number
WO2021231269A1
WO2021231269A1 PCT/US2021/031529 US2021031529W WO2021231269A1 WO 2021231269 A1 WO2021231269 A1 WO 2021231269A1 US 2021031529 W US2021031529 W US 2021031529W WO 2021231269 A1 WO2021231269 A1 WO 2021231269A1
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WIPO (PCT)
Prior art keywords
honeycomb body
porous walls
porous
honeycomb
metal
Prior art date
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PCT/US2021/031529
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English (en)
Inventor
Catherine Michelle BURDICK
Andrew Fleitz Husted
Rahul Suryakant KADAM
Elizabeth Marie Vileno
James William Zimmermann
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Corning Incorporated
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Application filed by Corning Incorporated filed Critical Corning Incorporated
Publication of WO2021231269A1 publication Critical patent/WO2021231269A1/fr

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    • C04B35/56—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides
    • C04B35/565—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide
    • C04B35/573—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide obtained by reaction sintering or recrystallisation
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
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    • B01D46/2418—Honeycomb filters
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    • B01D46/2429—Honeycomb filters characterized by parameters related to the physical properties of the honeycomb structure material of the honeycomb walls or cells
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Definitions

  • the present disclosure relates generally to conductive honeycomb bodies with electrically resistive heating capability, including ceramic honeycombs that are useful in the treatment of organic compounds in a flow stream.
  • Ceramic honeycombs have been utilized extensively in the automotive industry for pollution and emission control.
  • honeycomb bodies that offer improved efficiencies in exhaust treatment, along with methods of making these honeycomb bodies.
  • An aspect of the disclosure pertains to an electrically conductive honeycomb body that comprises: a porous honeycomb structure comprising a plurality of intersecting porous walls arranged to provide a matrix of cells, the porous walls comprising wall surfaces that define a plurality of channels extending from an inlet end to an outlet end of the structure.
  • the porous walls are comprised of a ceramic composite material that comprises at least one carbide phase and at least one silicide phase, each carbide and silicide phase comprising one or more metal compounds, each metal compound comprising one or more of Si, Mo, Ti, Zr and W. Further, the porous walls have an electrical conductivity that does not decrease upon exposure to 10% steam and 20% oxygen gas at 1000°C for 100 hours.
  • An aspect of the disclosure pertains to an electrically conductive honeycomb body that comprises: a porous honeycomb structure comprising a plurality of intersecting porous walls arranged to provide a matrix of cells, the porous walls comprising wall surfaces that define a plurality of channels extending from an inlet end to an outlet end of the structure.
  • the porous walls are comprised of a ceramic composite material that comprises at least one carbide phase and at least one silicide phase, each carbide and silicide phase comprising one or more metal compounds, each metal compound comprising one or more of Si, Mo, Ti, Zr and W.
  • the ceramic composite material is derived in part from a carbon precursor that comprises one or more of a natural carbon source, a graphite source, an amorphous carbon source, and a polyacrylonitrile (PAN) source.
  • An aspect of the disclosure pertains to a method of making an electrically conductive honeycomb body that comprises: mixing a plurality of ingredients together into a mixture, the ingredients comprising (a) a metal powder selected from the group consisting of Mo, Ti, Zr and W metal powder, (b) a silicon (Si) metal powder, (c) a carbon precursor and (d) a liquid vehicle; extruding the mixture into a green honeycomb body; drying the green honeycomb body in air at a temperature from about 50°C to about 200°C; heat treating the green honeycomb body in an inert atmosphere at a temperature from about 300°C to about 900°C; and firing the green honeycomb body in an inert atmosphere at a temperature from about 1400°C to about 2000°C to form an electrically conductive honeycomb body, the honeycomb body comprising a porous honeycomb structure comprising a plurality of intersecting porous walls arranged to provide a matrix of cells, the porous walls comprising wall surfaces that define a plurality of channels
  • the porous walls are comprised of a ceramic composite material that comprises at least one carbide phase and at least one silicide phase, each carbide and silicide phase comprising one or more metals selected from the group consisting of Si, Mo, Ti, Zr and W.
  • the carbon precursor comprises one or more of a natural carbon source, a graphite source, an amorphous carbon source, and a polyacrylonitrile (PAN) source.
  • the porous walls further comprise an electrical conductivity that does not decrease upon exposure to 10% steam and 1% oxygen gas at 1000°C for 200 hours.
  • the porous walls of the honeycomb body can have an electrical conductivity from about 1 S/cm to about 4000 S/cm.
  • the porous walls can comprise a median pore size from about 1 pm to about 15 pm.
  • the porous walls can also comprise a median porosity from about 35% to about 75%.
  • the porous walls can be substantially devoid of free metals, and in particular, free silicon metal.
  • substantially devoid as used herein, it is meant that the composition of an article, mixture, or composite contains less than 0.5 wt.% of a specified material (e.g., free silicon metal).
  • the composition of an article, mixture, or composite can contain less than 0.1 wt.% of a specified material (e.g., free silicon metal).
  • the composition comprises essentially none of the specified material, or is even devoid of the specified material (e.g., the porous walls contain essentially no free silicon metal, and more preferably contain no free silicon metal).
  • the natural carbon source can comprise one or more of a coconut powder, a flour, and a starch
  • the graphite source can comprise one or more of graphite powder and graphite fibers
  • the amorphous carbon source can comprise amorphous carbon fibers
  • the PAN source can comprise oxidized PAN fibers.
  • FIG. 1 is a perspective, schematic view of a catalytic remediation or other aftertreatment system (e.g., for gasoline and diesel engine exhaust gases) with a conductive honeycomb body according to an aspect of the disclosure;
  • a catalytic remediation or other aftertreatment system e.g., for gasoline and diesel engine exhaust gases
  • FIG. 1 A is a top-down, plan view of the system and conductive honeycomb body depicted in FIG. 1 ;
  • FIG. IB is an enlarged, top-down, schematic view of the conductive honeycomb body depicted in FIG. 1;
  • FIG. 1C is a perspective, schematic view of a catalytic remediation or other aftertreatment system (e.g., for gasoline and diesel engine exhaust gases);
  • a catalytic remediation or other aftertreatment system e.g., for gasoline and diesel engine exhaust gases
  • FIG. 2 is a schematic flow chart of a method of making a conductive honeycomb body according to an aspect of the disclosure
  • FIGS. 2A-2E are schematic flow charts of methods of making a conductive honeycomb body according to aspects of the disclosure.
  • FIGS. 3A-7B are x-ray diffraction (XRD) plots of exemplary conductive honeycomb body compositions, as prepared according to a method of making a ceramic honeycomb body and before and after 1000°C exposure in air for 100 hours, according to embodiments of the disclosure;
  • XRD x-ray diffraction
  • FIGS. 8A-10B are XRD plots of exemplary conductive honeycomb body compositions, as prepared according to a method of making a conductive honeycomb body and before and after 1000°C exposure in 10% steam/1 % O2 for 100 hours, according to embodiments of the disclosure;
  • FIGS. 11A and 11B are XRD plots of comparative conductive honeycomb body compositions, as prepared according to a method of making a conductive honeycomb body;
  • FIGS. 12A-12H are pore size distribution plots of exemplary conductive honeycomb body compositions, as prepared according to a method of making a conductive honeycomb body, according to an embodiment of the disclosure;
  • FIGS. 121 and 12J are pore size distribution plots of comparative conductive honeycomb body compositions, as prepared according to a method of making a conductive honeycomb body;
  • FIG. 13 is an XRD plot of a coconut powder carbon precursor, as carbonized at
  • FIGS. 14-18A are top-down schematic views of aftertreatment systems comprising a conductive honeycomb body according to various embodiments of the disclosure.
  • FIG. 18B is a side view of the aftertreatment system of FIG. 18 A;
  • FIGS. 19-21 are top-down schematic views of aftertreatment systems comprising non-honeycomb conductive bodies according to various embodiments of the disclosure.
  • FIG. 22A is a perspective view of an aftertreatment system comprising non honeycomb conductive bodies according to some embodiments of the disclosure; and [0030] FIG. 22B is a top-down view of the aftertreatment system of FIG. 22A.
  • aspects of the disclosure generally relate to conductive honeycomb bodies with electrically resistive heating capability that are useful in the removal of compounds from gasoline and diesel engine exhaust, such as carbon dioxide.
  • These honeycomb bodies can be directly heated by passing a current through their surfaces by virtue of the resistance and relatively high electrical conductivity of their ceramic composite material (e.g., as compared to cordierite, a material employed in conventional honeycomb structures).
  • these ceramic composites possess carbide and silicide phases that are formed in situ during processing, which results in a fine dispersion of these phases and porosity - attributes that drive electrical conductivity and treatment efficacy.
  • these ceramic honeycombs are comprised of ceramic composite materials with very high oxidation resistance, suitable for use in high temperature exhaust streams, e.g., as comprising steam and/or oxygen gas at temperatures in the vicinity of 1000°C.
  • embodiments of these honeycombs are substantially free of silicon metal, which helps ensure that the honeycomb is resistant to oxidation over its lifetime exposure to an oxidative, exhaust stream.
  • these honeycomb bodies can be derived from phenolic-free carbon precursors, which can also aid in their high temperature oxidation resistance.
  • aspects of the disclosure are also directed to methods of making these conductive honeycomb bodies.
  • the methods employ metal powders (e.g., Si metal powder and at least one of Mo, W, Ti and Zr metal powders), along with carbon precursors, typically from phenolic resin-free sources.
  • metal powders e.g., Si metal powder and at least one of Mo, W, Ti and Zr metal powders
  • carbon precursors typically from phenolic resin-free sources.
  • the methods do not rely on the use of ceramic materials as precursors.
  • the ceramic composites, as formed according to the methods possess very fine distributions of carbide and silicide phases that are formed in situ during the carbonization and firing aspects of the methods. Consequently, the resulting ceramic composites
  • the honeycomb bodies in the disclosure are lower in cost, and more favorable from an environmental and safety standpoint.
  • a catalytic converter assists in the treatment of these organic compounds, e.g., the removal and/or remediation of the compounds to simple and harmless compounds, thus limiting the contribution of the exhaust to environmental pollution.
  • a catalytic converter can comprise a ceramic honeycomb structure that is coated with noble precious metals as catalysts.
  • the exhaust gases from the gasoline or diesel engine flow through the honeycomb structure over a coated catalytic bed to undergo reactions to form simple harmless molecules such as O2, N2, CO2 and H2O.
  • Two types of catalysts used in catalytic converters include an oxidation catalyst and a reduction catalyst. Some of the different metals used as the catalyst are Pt, Pd, Rh, Ce, Fe, Mn and Ni. The catalysts can convert
  • the gases evolved from the engine can be hot in temperature and transfer heat to activate the catalyst to catalyze the reactions efficiently.
  • the porous honeycomb structures and bodies of this disclosure comprise ceramic composite materials that can be heated rapidly through electrical conduction of electrical current, e.g., within the first few seconds of the engine ignition.
  • a conductive honeycomb body 10 (also referred interchangeably herein as a conductive ceramic honeycomb body 10 and a honeycomb body 10) is depicted in schematic form within an aftertreatment system 15, e.g., a catalytic remediation system for gasoline and diesel engine exhaust gases.
  • the honeycomb body 10 comprises a ceramic composite 14a in the form of a porous honeycomb structure 14.
  • the porous honeycomb structure 14 can be defined by a length, 1, width, w, and a distance, L, between two sides 12, which can be arranged, for example, as electrodes or other electrically conductive members to assist in conducting a flow of electricity through the ceramic composite 14a of the honeycomb structure 14.
  • the sides 12 can be formed from a material that differs from the ceramic composite 14a, such as a metal or other highly conductive material.
  • the porous honeycomb structure 14 comprises one or more cells 16, or channels, that are defined by one or more porous walls 18 (see FIG. 1A).
  • the ceramic composite 14a comprises at least one carbide phase 70 and at least one silicide phase 80 different than the carbide phase 70 (see FIG. IB), each of which can be substantially dispersed within the composite 14a.
  • the carbide phase(s) 70 and the silicide phase(s) 80 each comprises a metal selected from the group consisting of Si, Mo, Ti, Zr and W. In the exemplary embodiment depicted in FIG.
  • the at least one carbide phase 70 can be silicon carbide 70a and the at least one silicide 80 is a metal di-silicide 80a and a metal tri-silicide 80b, e.g., M0S12 and M05S13, respectively.
  • the honeycomb body 10 can be arranged in an aftertreatment system 100 in which the honeycomb body 10 is used in conjunction with a separate aftertreatment device 101, which also comprises a honeycomb body 102 having a honeycomb structure 104 made from a porous ceramic material.
  • the honeycomb structure 104 comprises cells and intersecting walls akin to the cells 16 and walls 18 described with respect to the honeycomb body 10.
  • the aftertreatment device 101 can be or can comprise at least a portion of a catalytic converter assembly (e.g., its walls loaded with a catalytic material that treats one or more pollutants in a fluid stream), a particulate filter (e.g., having alternatingly plugged channels at opposite ends), and/or a partial filter (having both plugged and unplugged channels).
  • a catalytic converter assembly e.g., its walls loaded with a catalytic material that treats one or more pollutants in a fluid stream
  • a particulate filter e.g., having alternatingly plugged channels at opposite ends
  • a partial filter having both plugged and unplugged channels.
  • At least one of the honeycomb body 10 and the aftertreatment device 101 are loaded with a catalytic material, e.g., both the honeycomb body 10 and the aftertreatment device 101 are loaded with a catalytic material or only one of the honeycomb body 10 or the aftertreatment device 101 is so loaded.
  • the axial length, 1, of the honeycomb body 10 is short relative to the width, w, and distance, L (in contrast to the embodiment of FIG. 1, in which the axial length, 1, is relatively longer than the width, w, and the distance, L). In this way, the thermal mass of the honeycomb body 10 can be reduced (in comparison to an axially longer body) to enable the walls 18 of the honeycomb body 10 to heat up quickly.
  • the honeycomb body 10 can effectively form a heater for providing heat to catalytic material in the system 100 (the catalytic material carried by the honeycomb body 10 and/or by the honeycomb body 102). If the honeycomb body 10 does not carry any catalytic material, then the heat generated in the walls 18 can indirectly heat the catalytic material by positioning the honeycomb body 10 upstream of the aftertreatment device 101 in order to heat the fluid stream, which then heats and activates the catalytic material carried by the honeycomb body 102 as the fluid stream passes through the channels of the aftertreatment device 101.
  • the porous ceramic material of the honeycomb body 102 can comprise one or more of cordierite, aluminum titanate, silicon carbide, or other ceramic materials.
  • the material of the honeycomb body 102 can be different than the ceramic composite 14a, and need not be electrically conductive.
  • the shape and dimensions of the honeycomb body 102 or its features can also differ from the corresponding shape and dimensions of the honeycomb body 10 and its features (e.g., the cells 16 and walls 18).
  • sides 12 of the conductive honeycomb body 10 are conductive, and connected to leads 40. Further, these leads 40 are connected to an electrical power supply 48.
  • Various approaches can be employed to control the voltage of the power supply 48 in a time-dependent manner to effect temperature control of the honeycomb body 10 through resistive heating via passage of electrical current through the leads 40 and the sides 12 of the porous honeycomb structure 14.
  • the electrical conductivity of the honeycomb body 10, and its porous honeycomb structure 14 can be from about 1 S/cm to about 5000 S/cm, from about 1 S/cm to about 4000 S/cm, from about 5 S/cm to about 4000 S/cm, from about 10 S/cm to about 3000 S/cm, and all electrical conductivity values between these ranges.
  • the electrical conductivity of the honeycomb body 10, and its porous honeycomb structure 14, can be from about 1 S/cm to about 3000 S/cm, from about 5 S/cm to about 3000 S/cm, from about 10 S/cm to about 3000 S/cm, from about 20 S/cm to about 3000 S/cm, from about 1 S/cm to about 2500 S/cm, from about 5 S/cm to about 2500 S/cm, from about 10 S/cm to about 2500 S/cm, from about 20 S/cm to about 2500 S/cm, from about 1 S/cm to about 2000 S/cm, from about 5 S/cm to about 2000 S/cm, from about 10 S/cm to about 2000 S/cm, from about 20 S/cm to about 2000 S/cm, from about 1 S/cm to about 1000 S/cm, from about 5 S/cm to about 1000 S/cm, from about 10 S/cm to about 1000 S/cm, from
  • porous honeycomb structure is a shaped body comprising inner passageways, such as straight or serpentine channels and/or porous networks that would permit the flow of a fluid stream through the body, e.g., the ceramic composite 14a of the honeycomb structure 14.
  • the porous honeycomb structure 14 can comprise a dimension in a flow through direction of at least 1 cm, at least 2 cm, at least 3 cm, at least 4 cm, at least 5 cm, at least
  • the porous honeycomb structure 14 has a honeycomb structure comprising an inlet end, an outlet end, and inner channels extending from the inlet end to the outlet end.
  • the honeycomb structure comprises a multiplicity of cells extending from the inlet end to the outlet end, the cells being defined by intersecting cell walls, e.g., cell walls 18.
  • the cells at the inlet and outlet ends are open, or unplugged.
  • honeycomb structure could optionally comprise one or more selectively plugged honeycomb structure cell ends to provide a wall flow-through structure that allows for more intimate contact between the cell walls and the fluid stream (e.g., the exhaust stream that includes gases and/or particulates from gasoline and diesel engines).
  • the fluid stream e.g., the exhaust stream that includes gases and/or particulates from gasoline and diesel engines.
  • the porous honeycomb structure 14, as depicted in exemplary form in FIG. 1, comprises a surface having a surface area of 100 m 2 /g or more, 200 m 2 /g or more, 300 m 2 /g or more, 400 m 2 /g or more, or 500 m 2 /g or more.
  • the porous honeycomb structure 14 comprises a median pore size (i.e., the median of a population of longest dimension or diameter of pores) in the range of from about 0.5 pm to about 20 pm, from about 1 pm to about 15 pm, from about 1 pm to about 10 pm, from about 2 pm to about 10 pm, and all median pore size values between these median pore size ranges.
  • a median pore size i.e., the median of a population of longest dimension or diameter of pores
  • the porous honeycomb structure 14 can have a median porosity (i.e., the median of a population of porosity measurements of one or more honeycomb structures 14) from about 35% to about 75%, from about 40% to about 75%, from about 45% to about 75%, from about 50% to about 75%, and all median porosities between these median porosity ranges.
  • a median porosity i.e., the median of a population of porosity measurements of one or more honeycomb structures 14
  • a median porosity i.e., the median of a population of porosity measurements of one or more honeycomb structures 14
  • the porous honeycomb structure 14 has a pore volume from about 0.1 ml/g to about 0.6 ml/g, from about 0.1 ml/g to about 0.5 ml/g, from about 0.15 ml/g to about 0.5 ml/g, from about 0.2 ml/g to about 0.5 ml/g, and all pore volumes between these pore volume ranges.
  • the pores of the porous honeycomb structure 14 create an “interconnecting porosity,” defined herein as being characterized by pores which connect into and/or intersect other pores to create a tortuous network of porosity within the honeycomb structure 14.
  • the porous honeycomb structure 14 depicted in FIGS. 1, 1A and IB can be characterized by a surface area available for contact with a metal catalyst (not shown).
  • a metal catalyst not shown
  • the porous honeycomb structure 14 is characterized by a cell density ranging from about 6 cells per square inch (“cpsi”) to about 1200 cpsi.
  • the cell density of the porous honeycomb structure 14 can range from about 50 cpsi to about 900 cpsi.
  • certain implementations of the porous honeycomb structure 14 can be characterized by a cell density from about 100 cpsi to about 600 cpsi.
  • the porous honeycomb structure 14 as depicted in exemplary form in FIG. 1, can be characterized with at least one cell wall 18 having a thickness that ranges from about 0.001 inches to about 0.050 inches.
  • Other embodiments of the porous honeycomb structure 14 can be characterized with at least one cell wall 18 having a thickness that ranges from about 0.002 inches to about 0.040 inches. More generally, increases to cell density and wall thickness of the porous honeycomb structure 14 result in higher bulk density levels and adsorbent capacity.
  • porous honeycomb structure 14 has a geometric surface area from about 10 to about 60 squared centimeters per cubic centimeter (cm 2 /cm 3 ) of structure, or about 20 cm 2 /cm 3 to about 50 cm 2 /cm 3 , or even from about 20 cm 2 /cm 3 to about 30 cm 2 /cm 3 .
  • the porous honeycomb structure 14 of the conductive ceramic honeycomb body 10 depicted in FIGS. 1, 1 A and IB can also be characterized by a specific surface area as measured by a Brunauer- Emmett-Teller (“BET”) method according to standard principles understood in the field of specific surface area measurement methodology.
  • BET Brunauer- Emmett-Teller
  • the honeycomb body 10 is characterized by a specific surface area from about 50 m 2 /g to about 1000 m 2 /g. In some aspects, the specific surface area of the honeycomb body 10 is from about 100 m 2 /g to about 600 m 2 /g. In another aspect, the specific surface area of the honeycomb body 10 is from about 100 m 2 /g to about 200 m 2 /g. In a further aspect, the specific surface area of the honeycomb body 10 is from about 400 m 2 /g to about 600 m 2 /g. [0051] Referring again to the conductive ceramic honeycomb body 10, and the porous honeycomb structure 14 shown in FIG.
  • the ceramic composite 14a comprises at least one carbide phase 70 and at least one silicide phase 80. These phases 70, 80 can be substantially dispersed within the composite 14a.
  • the carbide phase 70 is the primary phase in the sense that it forms a matrix with the at least one silicide phase 80 as second phases within the matrix.
  • the carbide phase(s) 70 and the silicide phase(s) 80 each comprise a metal selected from the group consisting of Si, Mo, Ti, Zr and W. In the exemplary embodiment depicted in FIG.
  • the at least one carbide phase 70 is silicon carbide 70a (SiC) and the at least one silicide 80 can be a metal di-silicide 80a and a metal tri-silicide 80b, e.g., MoSi2 and M05S13, respectively.
  • the ceramic composite 14a is substantially devoid of free silicon (Si) metal; rather, the silicon in the composite 14a is in the form of the at least one silicide phase 80 and, in some aspects, as the at least one carbide phase 70 in the form of a silicon carbide phase 70a (SiC).
  • the ceramic composite 14a (and/or the corresponding porous honeycomb structure 14 in this or any other example) is substantially devoid of free metals; instead, any such metals (e.g., Si, Mo, Ti, Zr, or W) are in the form of the at least one silicide phase 80 or the at least one carbide phase 70.
  • the ceramic composite 14a comprises essentially no free silicon metal (i.e., Si), and in further embodiments the ceramic composite 14a and/or porous honeycomb structure 14 comprises essentially no free metals. Similar to the above, instead of being included as free metals, any metal in the composite 14a can be in the form of the at least one silicide phase 80 and/or the at least one carbide phase 70.
  • stoichiometric amounts of the components of the silicide and carbide phases, including metals can be selected to form the silicide and/or carbide phases in situ such that the composite 14a is substantially devoid of free metal, more preferably contains essentially no free metal, or even more preferably contains no free metals.
  • the ceramic composite 14a comprises no free silicon metal, and/or no free metals of any kind. According to some embodiments, the ceramic composite 14a is substantially devoid of free silicon metal, and/or free metals of any kind. In some embodiments, the ceramic composite 14a or porous honeycomb structure 14 being substantially devoid of free metals (or otherwise comprising no free metals) advantageously results in a relatively more electrically conductive honeycomb body with lower thermal expansion in comparison to bodies containing free metals. In other words, minimizing the amount of free metals, and in particular free silicon metal, can be used in some embodiments to promote desirable properties of the conductive ceramic honeycomb body 10, such as increased electrical conductivity and decreased thermal expansion, in comparison to honeycomb bodies having free metals therein.
  • oxidation of free metals can adversely affect various parameters (e.g., by decreasing thermal shock performance, decreasing electrical conductivity, and/or increasing thermal expansion).
  • free silicon metal in particular, promotes the formation of cristobalite when oxidized, which is a very high expansion silica crystal with relatively poor electrical conductivity.
  • embodiments of the honeycomb body 10 can comprise a ceramic composite 14a with porous walls 18 that comprise less than 1 wt.% free silicon metal, less than 0.75 wt.% free silicon metal, less than 0.5 wt.% free silicon metal, less than 0.1 wt.% free silicon metal, or less than 0.05 wt.% free silicon metal.
  • the ceramic composite 14a comprises at least one carbide phase 70 at a volume fraction from about 40% to about 95% and at least one silicide phase 80 at a volume fraction from about 5% to about 60%.
  • the at least one carbide phase 70 is at a volume fraction from about 45% to about 90% and the at least one silicide phase is at a volume fraction from about 10% to about 55%.
  • the volume fraction of SiC can range from about 45% to about 90% and the total volume fraction of the M0S12 and M05S13 can range from about 10% to about 55%.
  • the porous honeycomb structure 14 can be in the form of a ceramic composite 14a that comprises at least one carbide phase 70 and at least one silicide phase 80, each comprising one or more metal compounds.
  • each carbide phase 70 and silicide phase 80 comprise one or more metal compounds, with each metal compound comprising one or more of Si, Mo, Ti, Zr and W.
  • the ceramic composite 14a can be derived from a precursor mixture that comprises: (a) at least one of Mo, Ti, Zr and W metal, (b) a silicon (Si) metal, and (c) a carbon precursor.
  • the at least one of Mo, Ti, Zr and W metal can be in the form of metal powder - e.g., as Mo metal powder, Ti metal powder, Zr metal powder, W metal powder, and combinations thereof.
  • the silicon (Si) metal can also be in the form of silicon metal powder.
  • the carbon precursor is phenolic-free. According to embodiments, the carbon precursor comprises one or more of a natural carbon source, a graphite source, an amorphous carbon source, and a polyacrylonitride (PAN) source.
  • PAN polyacrylonitride
  • the natural carbon sources can comprise one or more of a sugar, a coconut powder, a flour (e.g., a wheat flour, corn flour, maize flour, potato flour, rice flour, etc.), and a starch (e.g., a potato starch, pea starch, corn starch, etc.).
  • the graphite source can comprise one or more of graphite powder and graphite fibers or graphite whiskers.
  • the amorphous carbon source can comprise amorphous carbon fibers
  • the PAN source can comprise oxidized PAN fibers.
  • the natural carbon sources comprises organic flours, coconut powder and/or starches.
  • the carbon precursor such as one or more natural carbon sources
  • an organic binder such as a methyl-cellulose binder
  • a lubricant e.g., a LIGA sodium stearate lubricant from Peter Greven GmbH & Co.
  • vegetable oil or synthetic oil e.g., olive oil, olive oil, and olive oil.
  • the ceramic composites 14a can be derived from a mixture of one or more organic fdlers or binders.
  • organic binders include cellulose compounds.
  • Cellulose compounds include cellulose ethers, such as methylcellulose, ethylhydroxy ethylcellulose, hydroxybutylcellulose, hydroxybutyl methylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, hydroxypropylcellulose, hydroxypropyl methylcellulose, hydroxyethyl methylcellulose, sodium carboxy methylcellulose, and mixtures thereof.
  • methylcellulose binder is a METHOCELTM A series product, sold by the Dow Chemical Company
  • Example hydroxypropyl methylcellulose binders include METHOCELTM E, F, J, K series products, also sold by Dow. Binders in the METHOCELTM 310 Series products, also sold by Dow, can also be used in the context of the invention.
  • DowMETHOCELTM A4M is an example binder for use with a RAM extruder.
  • Dow METHOCELTM F240C is an example binder for use with a twin screw extruder.
  • the ceramic composites 14a can be derived from a mixture that comprises one or more lubricants or forming aids (also referred herein as a “plasticizer”).
  • exemplary forming aids include soaps, fatty acids, such as oleic, linoleic acid, sodium stearate, etc., polyoxyethylene stearate, etc., and combinations thereof.
  • Other additives that can be useful for improving the extrusion and curing characteristics of a batch employed in fabricating the ceramic composite are phosphoric acid and oil.
  • Exemplary oils include vegetable oils, petroleum oils with molecular weights from 250 to 1000, and other oils containing paraffinic, and/or aromatic, and/or alicyclic compounds.
  • Some useful oils are 3-IN-ONE® oil from the WD- 40 Company.
  • Other useful oils can include synthetic oils based on poly alpha olefins, esters, polyalkylene glycols, polybutenes, silicones, polyphenyl ether, chlorotrifluoroethylene (“CTFE”) oils, and other commercially available oils.
  • CTFE chlorotrifluoroethylene
  • Vegetable oils such as sunflower oil, sesame oil, peanut oil, soybean oil, etc., are also useful forming aids in the preparation of the mixture that ultimately forms the ceramic composite 14a.
  • the composite is derived from various percentages of the (a) at least one of Mo, Ti, Zr and W metal, (b) a silicon (Si) metal, and
  • the mole fraction of the at least one of Mo, Ti, Zr and W metal is from about 0.05 to about 0.5, the silicon (Si) metal is from about 0.4 to about 0.8 and the carbon
  • the mole fraction of Mo metal is from about 0.05 to about 0.25
  • the mole fraction of silicon (Si) metal is from about 0.5 to about 0.7
  • the mole fraction of carbon (C) provided from the carbon precursor is from about 0.15 to about 0.4.
  • the mole fraction of Ti metal is from about 0.15 to about 0.4
  • the mole fraction of silicon (Si) metal is from about 0.5 to about 0.7
  • the mole fraction of carbon (C) provided from the carbon precursor is from about 0.1 to about 0.2.
  • the ceramic composite 14a can be derived from a metal, silicon and carbon mixture such that the mole fractions of the (a) at least one of Mo, Ti, Zr and W metal, (b) silicon (Si) metal, and (c) carbon (C) provided from the carbon precursor are provided according to Table 1 below. Further, it should be understood that mixtures of Mo, Ti, Zr and W metal can be employed according to Table 1, with the mole fraction given by a mole fraction range representative of the amounts of the particular metals employed in the mixture.
  • a ceramic composite 14a derived from a mixture of Mo and Ti metal, Si metal and a carbon precursor can employ a mole fraction of metal (Mo and Ti) from about 0.1 to about 0.38, mole fraction of Si metal from about 0.43 to 0.70 and a mole fraction of carbon (C) provided from the carbon precursor from 0.10 to 0.35, as outlined below in Table 1.
  • Mo and Ti mole fraction of metal
  • Si metal mole fraction of Si metal from about 0.43 to 0.70
  • C mole fraction of carbon
  • the temperature of the conductive ceramic honeycomb body 10 depicted in FIGS. 1, and 1 A - 1C can be controlled by conduction of an electrical current through its porous honeycomb structure 14 to effect the rate of heating of a metal catalyst and/or the substrate for the metal catalyst (e.g., the honeycomb structure 14) for higher remediation efficiency.
  • the sides 12 of the honeycomb body 10 can be configured to be electrically conductive, and connected to leads 40 and an electrical power supply 48. Further, the sides 12 of the honeycomb body 10, which are configured to be conductive, are positioned so as to be able to conduct an electric current through the honeycomb, preferably in a uniform fashion. The actual positioning of the sides 12 depends on the geometry of the device.
  • the sides 12 of the honeycomb body 10 are not limited to any specific type of conductor or conductor geometry.
  • the current passing from the power supply 48 through the leads 40 generates a substantially uniform heating of the conductive ceramic honeycomb 10 without a prevalence of hot spots.
  • the resistivity of the honeycomb body 10, and its porous honeycomb structure 14, can be adjusted as desired according to the following equation: where p is resistivity in ohm- cm, R is resistance in ohms, A is the area of the conducting surface in cm 2 and L, as noted earlier, is the distance between two conducting surfaces in cm.
  • a conducting metal is applied to each of the opposing sides 12 (or surfaces) of the honeycomb and porous honeycomb structure 14.
  • opposing sides or “opposing surfaces” of the honeycomb body 10 are such that the sides or surfaces are so spaced according to the geometry of the porous honeycomb structure 14 and ceramic composite 14a such that passage of current between the conductive sides or surfaces produces a current that heats the porous honeycomb structure 14 in a substantially uniform fashion.
  • the opposing surfaces can be at any location (including a multitude of locations) on or within the honeycomb body 10 to enable substantially uniform heating of the porous honeycomb structure 14 with a current applied.
  • Exemplary conducting materials that can be employed for the opposing sides 12 (or opposing surfaces as the case for a porous honeycomb structure 14 without parallel opposed sides 12) include metals and metal alloys that contain one or more of copper, silver, aluminum, zinc, nickel, lead, and tin; and intermetallic compounds, such as MoSh, and composites, such as MoSE-SiC .
  • the sides 12 are coated with one or more materials having a higher electrical conductivity than the ceramic composite 14a (e.g., a silver- containing paint or paste) to allow for a more uniform distribution of electrical current and, therefore, a more even distribution of temperature within the porous honeycomb structure 14.
  • honeycombs with conductive sides 12 can be configured such that the sides 12 are in the form of, or otherwise comprise, a strip of conducting material on the porous honeycomb structure 14 of the honeycomb body 10. If an electrode is employed to connect to the side 12 as part of the lead 40, for example, it can be applied by a pressure contact, e.g., a spring.
  • a strip of conducting metal can be employed for this purpose and attached to the honeycomb body 10 and continuous body by an electrically conductive adhesive, e.g., a silver- containing epoxy such as E-Solder® #3012 and #3022 from Von Roll USA, Inc.
  • an electrically conductive adhesive e.g., a silver- containing epoxy such as E-Solder® #3012 and #3022 from Von Roll USA, Inc.
  • a copper coating is deposited for this purpose by a spray metal coating approach as understood by those with ordinary skill in the field.
  • the resistive heating of the conductive ceramic honeycomb body 10 and porous honeycomb structure 14 is driven largely by the composition of the ceramic composite 14a, which contains at least one carbide phase 70 and at least one silicide phase 80, the combination being an electrically conductive ceramic material.
  • the fine dispersion of the silicide phase(s) 80 within the at least one carbide phase 70, as formed in situ ensures that the conductivity of the ceramic composite 14a is high and yields substantially uniform heating capability.
  • the use of the phenolic-free carbon precursors as outlined earlier in this disclosure, can also ensure that the conductivity of the ceramic composite 14a is high, and relatively stable in high temperature, oxidative environments.
  • a sufficient temperature for exhaust remediation comprises heating the conductive honeycomb body 10, as coated with a metal catalyst, in the range of from about 50°C to about 700°C, including, for example, temperatures of 100°C, 150°C, 180°C, 200°C,
  • the sufficient heating temperature is in the range derived from these values, including, for example, a range from about 100°C to about 300°C, or about 200°C to about 500°C.
  • any conductive ceramic honeycomb body 10, and other honeycomb structures consistent with the principles of this disclosure can be incorporated into or used in other appropriate system environments.
  • the honeycomb bodies 10 of the disclosure can be employed in an exhaust stream of diesel automotive engines or other process streams. More generally, any one of the above-mentioned honeycomb bodies 10, and like-constructed honeycomb structures, can be incorporated into a system configuration where catalytic conversion of some components in the stream is desirable.
  • embodiments of the conductive honeycomb body 10 can be characterized by an electrical conductivity that is relatively stable, or even improved, during or after exposure to high temperature, oxidative environments.
  • the porous walls 18 of the ceramic composite 14a have an electrical conductivity that does not decrease upon exposure to 10% steam and 20% oxygen gas (O2) at temperatures up to, and including, 1000°C for durations up to, and including, 100 hours.
  • the porous walls 18 of the ceramic composite 14a can also be characterized by an electrical conductivity that does not decrease upon exposure to 10% steam and 1% oxygen gas
  • an electrical conductivity that “does not decrease upon exposure” to a particular environment means that the article, honeycomb body 10, or other structure consistent with the principles of the disclosure does experience a statistically significant decrease in its conductivity, as measured before and after the exposure, and evaluated according to standard statistical principles understood by those of skill in the field of the disclosure.
  • a method 200 of making a conductive ceramic honeycomb body 10 is provided as shown schematically in FIG. 2.
  • the method 200 comprises a step 208 of batching or otherwise providing a precursor batch comprising: (a) a metal powder selected from the group consisting of Mo, Ti, Zr and W metal powder, (b) a silicon (Si) metal powder and (c) a carbon precursor.
  • the mole fraction of the at least one of Mo, Ti, Zr and W metal powder is from about 0.05 to about 0.5
  • the silicon (Si) metal powder is from about 0.4 to about 0.8 and the carbon
  • the batching step 208 is conducted such that the batch is derived from a metal, silicon and carbon mixture defined by the mole fractions of the (a) at least one of Mo, Ti, Zr and W metal, (b) silicon (Si) metal, and (c) carbon (C) provided from the carbon precursor that are provided according to Table 1, as noted earlier.
  • the carbon precursor can comprise one or more of a natural carbon source, a graphite source, an amorphous carbon source, and a PAN source.
  • the natural carbon sources can comprise one or more of a sugar, a coconut powder, a flour (e.g., a wheat flour, corn flour, maize flour, rice flour, potato flour, etc.), and a starch (e.g., a potato starch, pea starch, corn starch, etc.).
  • the graphite source can comprise one or more of graphite powder and graphite fibers or graphite whiskers.
  • the amorphous carbon source can comprise amorphous carbon fibers
  • the PAN source can comprise oxidized PAN fibers.
  • the natural carbon sources comprises organic flours, coconut powder and/or starches.
  • phenolic-free carbon precursors in the method 200 of making a conductive honeycomb body 10 are lower in cost and require shorter heat treatment times (e.g., as in steps 240 and 250, described below) as compared to organic resin-based carbon precursors, such as phenolic resins.
  • Another advantage of these phenolic-free carbon precursors is that they can provide for better rheology control of the batch during extrusion and plasticization (e.g., as in steps 212 and 220, described below) as compared to a batch containing phenolic-based carbon precursors.
  • the method 200 further comprises a step 210 of mixing or otherwise mulling this precursor batch, e.g., in a conventional mulling apparatus as employed by those of ordinary skill in the field of the disclosure.
  • the step 210 of mixing the precursor batch is conducted from 10 to 60 minutes, preferably for about 15 to 30 minutes.
  • the carbon precursor e.g., a coconut powder
  • the carbon precursor is carbonized in an inert, oxygen-depleted atmosphere (e.g., in N2, Ar, and/or He gas) at 800°C or greater prior to the step 210 of mixing the batch (e.g., at 1000°C for 2 hours in an N2 atmosphere).
  • the method 200 also comprises a step 212 of plasticizing the precursor batch, e.g., within an extrusion apparatus as employed by those of ordinary skill in the field of the disclosure.
  • the method 200 further comprises a step 220 of extruding the batch into a green honeycomb body form (e.g., in a Loomis Model #232-40 extruder), followed by a step 230 of drying or otherwise curing the green honeycomb body form in air from about 50°C to about 200°C, preferably at about 100 to 150°C.
  • the step 230 of drying or otherwise curing the batch can be conducted from 30 minutes to 24 hours, depending on the upper temperature of this step.
  • step 230 is conducted at about 100°C in air for about 4 to 6 hours.
  • the method 200 of making a conductive ceramic honeycomb body 10 further comprises a step 240 of heat treating the green honeycomb body form in an inert atmosphere (e.g., in N2, Ne, Ar, and/or He gas) from about 300°C to about 900°C, preferably between 750°C and 900°C.
  • an inert atmosphere e.g., in N2, Ne, Ar, and/or He gas
  • the method 200 comprises a step 250 of firing the green honeycomb body form in an inert atmosphere (e.g., in He and/or Ar gas) from about 1400°C to about 2000°C, preferably from about 1450°C to about 1900°C, to form the conductive ceramic honeycomb body 10, the honeycomb comprising a porous honeycomb structure 14.
  • the honeycomb structure 14 is a ceramic composite 14a that comprises at least one carbide phase 70 and at least one silicide phase 80, each carbide and silicide phase comprising a metal selected from the group consisting of Si, Mo, Ti, Zr and W. It should also be understood that the method 200 results in a conductive ceramic honeycomb body 10, as detailed earlier in the disclosure (see FIGS. 1-lB and corresponding description).
  • the steps 210, 212 and 220 of mixing, plasticizing and extruding the precursor batch of forming the mixture into a green honeycomb body form can be conducted according to various approaches.
  • the mixture can be formed into a shape, for example, a honeycomb, by any appropriate technique, such as by extrusion.
  • Plasticizing and extrusion of the precursor batch i.e., a mixture comprising: (a) a metal powder selected from the group consisting of Mo, Ti, Zr and W metal powder, (b) a silicon (Si) metal powder and (c) a carbon precursor) in steps 212 and 220 can be conducted by using standard extruders and extrusion equipment (e.g., a ram extruder, a single screw extruder, a double-screw extruder, and others), along with custom dies to make porous honeycomb structures of various shapes and geometries. As noted earlier, the presence of forming aids and plasticizers in the mixture can aid in the step 210 of mixing the precursor batch.
  • standard extruders and extrusion equipment e.g., a ram extruder, a single screw extruder, a double-screw extruder, and others
  • the step 230 of drying or otherwise curing the green honeycomb body form can also be conducted according to various approaches.
  • the green honeycomb body form e.g., as comprising the precursor batch
  • the green honeycomb body form can be heated in an oven at about 50°C to about 200°C for a few minutes to a few hours in ambient or an inert atmosphere to dry the mixture.
  • any such organic resin constituents in the green honeycomb body form can be cured by heating the mixture in air at atmospheric pressures and at a temperature from about 70°C to about 200°C for about 0.5 hours to about 24 hours.
  • the green honeycomb body form is heated from a low temperature to a higher temperature in stages, for example, from about 70°C to about 90°C, to about 125°C, to about 150°C, each temperature being held for a few minutes to hours.
  • curing can also be accomplished by adding a curing additive such as an acid additive at room temperature, an ultraviolet (UV)-sensitive catalyst and applying UV light, and others.
  • the method 200 depicted in FIG. 2 comprises a step 240 of heat treating the carbon precursor in the green honeycomb body form.
  • the carbon constituents in the green honeycomb body form can be carbonized by this step (e.g., to the extent not already carbonized prior to the step 210 of mixing the batch) by subjecting the green body to an elevated carbonizing temperature in an Ch-depleted atmosphere.
  • the heat treatment temperature can range from about 300°C to about 900°C and, in certain embodiments, it can range from about 700°C to about 900°C.
  • the heat treating atmosphere can be inert, primarily comprising a non-reactive gas such as N2, Ne, Ar, and mixtures thereof.
  • organic substances contained in the green honeycomb body form e.g., methylcellulose, lubricants, binders, processing aids, etc.
  • organic substances contained in the green honeycomb body form can decompose to leave a carbonaceous residue with a high surface area.
  • the method 200 proceeds to step 250 of firing the green honeycomb body form, e.g., after completion of the curing and heat treating steps 230 and 240, respectively.
  • step 250 of firing the green honeycomb body form is also conducted in an inert atmosphere.
  • the non-reactive gases employed in this step should not include nitrogen, as inclusion of nitrogen would likely result in the formation of nitride phases(s), the presence of which would degrade the electrical conductivity of the resulting honeycomb.
  • step 250 of firing the green honeycomb body form can be conducted from about 1400°C to about 2000°C, e.g., at 1450°C, 1500°C, 1550°C, 1600°C, 1650°C, 1700°C, 1750°C, 1800°C, 1850°C, 1900°C, 1950°C, 2000°C, and all firing temperatures between these temperatures.
  • the result of step 250 is the formation of the conductive ceramic honeycomb body 10, the honeycomb body 10 comprising a porous honeycomb structure 14 in which the honeycomb structure 14 is a ceramic composite 14a (see also FIGS. 1-lB).
  • FIGS. 2A-2E schematic flow charts of methods 200a-200e of making a conductive honeycomb body 10 are depicted, according to aspects of the disclosure.
  • Each of the methods 200a-200e are substantially similar to, and exemplary of, the method 200 of making a conductive honeycomb body 10 depicted in FIG. 2 and described above.
  • like- numbered steps of the method 200 employed in the methods 200a-200e have the same or substantially the same features and aspects.
  • method 200a is conducted such that the drying step 230 is conducted at 100°C for 5 hours in air; the heat treating step 240 is conducted from room temperature to 900°C in an N2 atmosphere with a dwell time of 2 hours (with various intermediate steps); and the firing step 250 is conducted from room temperature to 1800°C in an Ar atmosphere with a dwell time of 6 hours (with various intermediate steps).
  • method 200b is conducted such that the drying step 230 is conducted at 100°C for 5 hours in air; the heat treating step 240 is conducted from room temperature to 900°C in an N2 atmosphere with a dwell time of 15 minutes (with an intermediate step); and the firing step 250 is conducted from room temperature to 1800°C in an Ar atmosphere with a dwell time of 6 hours (with various intermediate steps).
  • method 200c is conducted such that the drying step 230 is conducted at 100°C for 5 hours in air; and the firing step 250 is conducted from room temperature to 1800°C in an Ar atmosphere with a dwell time of 6 hours (with various intermediate steps). As is also evident in FIG. 2C, the method 200c is conducted without a heat treating step 240, as the firing step 250 is sufficient.
  • method 200d is conducted such that the drying step 230 is conducted at 100°C for 5 hours in air; the heat treating step 240 is conducted from room temperature to 900°C in an N2 atmosphere with a dwell time of 2 hours (with various intermediate steps); and the firing step 250 is conducted from room temperature to 1650°C in an Ar atmosphere with a dwell time of 2 hours (with various intermediate steps).
  • method 200e is conducted such that the drying step 230 is conducted at 100°C for 5 hours in air; and the firing step 250 is conducted from room temperature to 1650°C in an Ar atmosphere with a dwell time of 2 hours (with various intermediate steps). As is also evident in FIG. 2E, the method 200e is conducted without a heat treating step 240, as the firing step 250 is sufficient.
  • Examples 1-21 and 24-29 were prepared according to methods of making conductive ceramic honeycombs, as noted in detail below. Comparative Examples 22 and 23 were also prepared, as noted in further detail below.
  • Each of the honeycomb bodies of Examples 1-21 and 24-29 were prepared according to methods of making conductive ceramic honeycombs, as noted in detail below. Comparative Examples 22 and 23 were also prepared, as noted in further detail below.
  • each of the methods employed to fabricate these honeycomb bodies is consistent with the methods 200-200e of making conductive ceramic honeycombs of the disclosure (see FIGS. 2-2E and corresponding description).
  • the conductive ceramic honeycomb bodies prepared in these examples were characterized to determine their electrical conductivity (S/cm), skeletal density (g/cc), pore size (pm), porosity (%) and pore volume (ml/g). Further, the mole fractions of the metal (Mo) precursors, silicon (Si) metal, and carbon (C) provided from the carbon precursors employed to fabricate these conductive ceramic honeycomb bodies are provided in the descriptions below.
  • Examples 1-21, 24-29 and Comparative Examples 22 and 23 were prepared as follows. All of the Examples 1-21 and 24-29 employ coconut powder as a carbon precursor in the initial batch.
  • the carbon was prepared from coconut shell powder (as manufactured by A&E Connock) that was carbonized at 1000°C for 2 hours in a N2 atmosphere.
  • the resulting carbon was characterized as having a particle size of about 3 to 5 pm with a surface area of 39.56 m 2 /gm.
  • An XRD plot obtained for this carbon derived from coconut powder is provided in FIG. 13, which shows that the carbon is completely amorphous.
  • a precursor batch was prepared by mixing the following constituents: 45.42 wt.% Mo powder (1-5 pm particle size), 44.80 wt.% Si powder (10-13 pm particle size), 2.78 wt.% coconut powder (3-5 pm particle size), 6 wt.% MM1 -hydroxypropyl methylcellulose A4M and 1 wt.% sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) in a polyethylene jar. Accordingly, the mole fraction ratio of Mo: Si: C for this precursor batch was 0.205:0.695:0.100.
  • the mixture was mulled for about 5 minutes.
  • Thermo Fisher Scientific Isotemp® heating oven e.g., in a Thermo Fisher Scientific Isotemp® heating oven
  • the rigid structure was then cut into 2 inch pieces and fired according to the schedule set forth in FIG. 2A in a graphite- lined furnace.
  • the resulting conductive ceramic honeycomb body was then subjected to the following characterization: mercury porosimetry, strength testing, and XRD analysis.
  • the honeycomb bodies were also subjected to electrical conductivity testing by a four- probe electrical conductivity method using a Keithley® Model 2002 multimeter.
  • the XRD pattern of this example honeycomb body demonstrated the existence of a highly crystalline material, principally with
  • Pore size, porosity and pore volume for this example was measured at 6.85 pm, 61.57% and 0.316 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in air for 100 hours, and showed no phase changes and a conductivity of 1185.47 S/cm after the test. Further, the sample showed no cracks after firing.
  • Pore size, porosity and pore volume for this example was measured at 6.39 pm, 59.77% and 0.294 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in air for 100 hours, and showed no phase changes and a conductivity of 1492.40 S/cm after the test. Further, the sample showed no cracks after firing.
  • Example 4 Example 4:
  • Pore size, porosity and pore volume for this example was measured at 5.79 pm, 66.73% and 0.444 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in air for 100 hours, and showed no phase changes and a conductivity of 150.22 S/cm after the test. Further, the sample showed no cracks after firing.
  • Pore size, porosity and pore volume for this example was measured at 6.13 pm, 68.68% and 0.472 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in air for 100 hours, and showed no phase changes and a conductivity of 94.60 S/cm after the test. Further, the sample showed no cracks after firing.
  • A4M and 1 weight % sodium stearate (LIGA SS3 SG3 sodium stearate).
  • the mole fraction ratio of Mo:Si:C for this precursor batch was 0.137:0.596:0.267.
  • the sample was mixed according to the procedure of Example 1 and fired using the schedule set forth in FIG. 2B.
  • the measured conductivity was 48.53 S/cm, and the skeletal density was 4.5 grams/cm 3 . Pore size, porosity and pore volume for this example was measured at 5.65 pm, 66.43% and 0.448 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in air for 100 hours, and showed no phase changes and a conductivity of 47.49 S/cm after the test. Further, the sample showed no cracks after firing.
  • Pore size, porosity and pore volume for this example was measured at 6.00 pm, 68.89% and 0.469 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in air for 100 hours, and showed no phase changes and a conductivity of 19.61 S/cm after the test. Further, the sample showed no cracks after firing.
  • Example 9 A4M and 1 weight % sodium stearate (FIGA SS3 SG3 sodium stearate).
  • the mole fraction ratio of Mo:Si:C for this precursor batch was 0.137:0.596:0.267.
  • the sample was mixed according to the procedure of Example 1 and fired using the schedule set forth in FIG. 2B.
  • the skeletal density was 4.5 grams/cm 3 .
  • Pore size, porosity and pore volume for this example was measured at 9.25 pm, 71.22% and 0.502 ml/g, respectively. The sample was too brittle for conductivity characterization and not subjected to an oxidation test. [0101]
  • Example 9 Example 9:
  • A4M and 1 weight % sodium stearate (LIGA SS3 SG3 sodium stearate).
  • the mole fraction ratio of Mo:Si:C for this precursor batch was 0.205:0.695:0.100.
  • the sample was mixed according to the procedure of Example 1 and fired using the schedule set forth in FIG. 2C.
  • the measured conductivity was 899.69 S/cm, and the skeletal density was 4.97 grams/cm 3 .
  • Pore size, porosity and pore volume for this example was measured at 9.06 pm, 67.28% and 0.396 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in air for 100 hours, and showed no phase changes and a conductivity of 913.45 S/cm after the test. Further, the sample was brittle and shed some powder.
  • Pore size, porosity and pore volume for this example was measured at 8.47 pm, 73.29% and 0.564 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in air for 100 hours, and showed no phase changes and no conductivity (0 S/cm) after the test.
  • Example 14 Pore size, porosity and pore volume for this example was measured at 6.02 pm, 68.82% and 0.440 ml/g, respectively. The sample was tested for oxidation stability at 1000°C in air for 100 hours, and showed no phase changes and a conductivity of 412.39 S/cm after the test. [0111]
  • Example 14
  • Pore size, porosity and pore volume for this example was measured at 10.38 pm, 59.08% and 0.322 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in 10% steam and 1% O2 for 100 hours, and showed a conductivity of 95.16 S/cm after the test.
  • Pore size, porosity and pore volume for this example was measured at 10.83 pm, 58.48% and 0.326 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in 10% steam and 1% O2 for 100 hours, and showed a conductivity of 46.19 S/cm after the test.
  • the mole fraction ratio of Mo:Si:C for this precursor batch was 0.109:0.580:0.310.
  • the sample was mixed according to the procedure of Example 1 and fired using the schedule set forth in FIG. 2A.
  • the measured conductivity was 9.87 S/cm, and the skeletal density was 4.36 grams/cm 3 .
  • Pore size, porosity and pore volume for this example was measured at 8.22 pm, 58.50% and 0.330 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in 10% steam and 1% O2 for 100 hours, and showed a conductivity of 17.88 S/cm after the test.
  • Pore size, porosity and pore volume for this example was measured at 8.37 pm, 58.59% and 0.324 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in 10% steam and 1% O2 for 100 hours, and showed a conductivity of 9.88 S/cm after the test.
  • Example 1 (5-10 pm particle size), 49.69 weight % Si powder (10-13 pm particle size), 11.38 weight % coconut powder-based carbon (3-5 pm particle size), 6 weight % MM3-hydroxypropyl methylcellulose F240 and 1 weight % oleic acid.
  • the mole fraction ratio of Mo:Si:C for this precursor batch was 0.109:0.580:0.310.
  • the sample was mixed according to the procedure of Example 1 and fired using the schedule set forth in FIG. 2A.
  • the measured conductivity was 8.66 S/cm, and the skeletal density was 4.36 grams/cm 3 . Pore size, porosity and pore volume for this example was measured at 8.23 pm, 59.83% and 0.333 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in 10% steam and 1% O2 for 100 hours, and showed a conductivity of 10.90 S/cm after the test.
  • Pore size, porosity and pore volume for this example was measured at 11.63 pm, 60.20% and 0.347 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in 10% steam and 1% O2 for 100 hours, and showed a conductivity of 14.66 S/cm after the test.
  • Pore size, porosity and pore volume for this example was measured at 12.44 pm, 64.18% and 0.409 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in 10% steam and 1% O2 for 100 hours, and showed a conductivity of 11.73 S/cm after the test.
  • Pore size, porosity and pore volume for this example was measured at 6.96 pm, 65.72% and 0.448 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in 10% steam and 20% O2 for 100 hours, and showed a conductivity of 72.23 S/cm after the test.
  • Pore size, porosity and pore volume for this example was measured at 6.97 pm, 61.10% and 0.361 ml/g, respectively.
  • the sample was tested for oxidation stability at 1000°C in 10% steam and 20% O2 for 100 hours, and showed a conductivity of 131.42 S/cm after the test.
  • Example 25 The measured conductivity of this example was 45.84 S/cm. The sample was tested for oxidation stability at 1000°C in 10% steam and 20% O2 for 100 hours, and showed a conductivity of 85.78 S/cm after the test. [0133]
  • Example 25 The measured conductivity of this example was 45.84 S/cm. The sample was tested for oxidation stability at 1000°C in 10% steam and 20% O2 for 100 hours, and showed a conductivity of 85.78 S/cm after the test. [0133]
  • Example 25 Example 25 :
  • the measured conductivity of this example was 27.86 S/cm.
  • the sample was tested for oxidation stability at 1000°C in 10% steam and 20% O2 for 100 hours, and showed a conductivity of 46.20 S/cm after the test.
  • the sample was tested for oxidation stability at 1000°C in 10% steam and 20% O2 for 100 hours, and showed no retention of conductivity after the test.
  • the sample was tested for oxidation stability at 1000°C in 10% steam and 20% O2 for 100 hours, and showed no retention of conductivity after the test.
  • the measured conductivity of this example was 36.40 S/cm.
  • the sample was tested for oxidation stability at 1000°C in 10% steam and 0.04% O2 for 200 hours, and showed a conductivity of 35.04 S/cm after the test.
  • the measured conductivity of this example was 36.89 S/cm.
  • the sample was tested for oxidation stability at 1000°C in 10% steam and 0.04% O2 for 200 hours, and showed a conductivity of 38.93 S/cm after the test.
  • XRD x-ray diffraction
  • FIGS. 11 A and 1 IB are XRD plots of comparative conductive honeycomb body compositions from Comparative Examples 22 and 23, as prepared as outlined earlier with a firing at 1800°C for 6 hours. As noted above in the descriptions of these examples, each of these conductive honeycomb compositions contains Mo, C and Si. As is evident from the XRD plots in FIGS. 3A-11B, the conductive ceramic honeycomb bodies each possess M0S12, M05S13 and SiC phases.
  • FIGS. 12A-12H and FIGS. 121 and 12J pore size distribution plots are provided of exemplary conductive honeycomb body compositions from Examples 4-7, 11, 14, 16, and 18 and Comparative Examples 22 and 23, respectively. As noted earlier, these pore size distribution plots were obtained through mercury porosimetry measurement techniques. Further, the pore sizes reported earlier for each of these Examples correspond to the peaks shown in these figures.
  • FIG. 14 illustrates an aftertreatment system 300
  • the conductive ceramic composite 14a is formed into a honeycomb body
  • the honeycomb body 302 comprises a honeycomb structure comprising a matrix of intersecting walls and cells, akin to the cells 16 and walls 18 of honeycomb body 10.
  • the aftertreatment system 300 comprises electrodes 304, which are coupled via the leads 40 to the power source 48.
  • FIG. 15 illustrates an aftertreatment system 400 (e.g., for catalytic remediation or other treatment of a flow of fluid, e.g., exhaust from the engine of a vehicle) in which the conductive ceramic composite 14a is formed into a honeycomb body 402 having a cylindrical peripheral shape, similar to the honeycomb body 302 of FIG. 14.
  • the honeycomb body 402 comprises a honeycomb structure comprising a matrix of intersecting walls and cells, akin to the cells 16 and walls 18 of honeycomb body 10.
  • the aftertreatment system 400 comprises electrodes 404, which are coupled via the leads 40 to the power source 48.
  • the electrodes 404 of the aftertreatment system 400 are embedded into the sides of the honeycomb body 402 to further facilitate electrical conduction between the walls of the honeycomb body 402 and the electrodes 404.
  • FIG. 16 illustrates an aftertreatment system 500 (e.g., for catalytic remediation or other treatment of a flow of fluid, e.g., exhaust from the engine of a vehicle) in which the conductive ceramic composite 14a is formed into a honeycomb body 502 having a generally cylindrical peripheral shape, similar to the honeycomb bodies 302 and 402 of FIGS. 14 and 15.
  • the honeycomb body 502 comprises a honeycomb structure comprising a matrix of intersecting walls and cells, akin to the cells 16 and walls 18 of honeycomb body 10.
  • the aftertreatment system 500 comprises electrodes 504, which are coupled via the leads 40 to the power source 48.
  • the honeycomb body 502 comprises tapered protrusions 506 that extend laterally outward, and which tapered protrusions 506 are engaged with the electrodes 504.
  • the use of the tapered protrusions 506 may be useful in reducing the size of the electrodes 504, and/or to set a preferred shape for the electrodes (e.g., flat plates) as opposed to electrodes that are curved for circumferential engagement with a rounded honeycomb body (as shown in FIG. 14), or embedded into a rounded honeycomb body (as shown in FIG. 15).
  • a preferred shape for the electrodes e.g., flat plates
  • FIG. 17 illustrates an aftertreatment system 600 (e.g., for catalytic remediation or other treatment of a flow of fluid, e.g., exhaust from the engine of a vehicle) in which the conductive ceramic composite 14a is formed into a honeycomb body 602.
  • the honeycomb body e.g., for catalytic remediation or other treatment of a flow of fluid, e.g., exhaust from the engine of a vehicle.
  • the aftertreatment system 600 comprises electrodes 604, which are coupled via the leads 40 to the power source 48.
  • the honeycomb body 602 has a cross-sectional shape that resembles a circle that has been truncated and flattened by removing portions from opposite sides.
  • the arrangement of FIG. 17 may be advantageous to set a preferred shape for the electrodes 604 (e.g., flat plates) as opposed to electrodes that are curved for circumferential engagement with a rounded honeycomb body (as shown in FIG. 14), or embedded into a rounded honeycomb body (as shown in FIG. 15).
  • FIGS. 18A-18B illustrate an aftertreatment system 700 (e.g., for catalytic remediation or other treatment of a flow of fluid, e.g., exhaust from the engine of a vehicle) in which the conductive ceramic composite 14a is formed into a honeycomb body 702.
  • the honeycomb body 702 comprises a honeycomb structure comprising a matrix of intersecting walls and cells, akin to the cells 16 and walls 18 of honeycomb body 10.
  • the aftertreatment system 700 comprises electrodes 704, which are coupled via the leads 40 to the power source 48.
  • the honeycomb bodies e.g., for catalytic remediation or other treatment of a flow of fluid, e.g., exhaust from the engine of a vehicle
  • the conductive ceramic composite 14a is formed into a honeycomb body 702.
  • the honeycomb body 702 comprises a honeycomb structure comprising a matrix of intersecting walls and cells, akin to the cells 16 and walls 18 of honeycomb body 10.
  • the aftertreatment system 700 comprises electrodes 704, which are coupled via the
  • the honeycomb body 702 comprises electrodes 704 that are embedded in the honeycomb body 702. Also in contrast to the honeycomb bodies 302, 502 and 602, the honeycomb body 702 comprises electrodes 704 that are each embedded in individual cells of the honeycomb body 702.
  • the electrodes 704 can be shaped and sized to fit into one of the cells, and/or the electrodes 704 can be held in place by an adhesive, such as a conductive cement or other material (e.g., conductive ceramic, conductive polymer, metal, or composite thereof).
  • a conductive cement or other material e.g., conductive ceramic, conductive polymer, metal, or composite thereof.
  • Three pairs of the electrodes 704 are shown in FIG. 18A, however, any number of electrodes can be utilized.
  • FIG. 18B shows a side view of the aftertreatment system 700 to illustrate how the electrodes 704 can be secured into the honeycomb body 702.
  • a first one of the electrodes 704, designated with reference numeral 704a, is arranged such that an embedded portion
  • the electrode 704a is inserted into one of the cells of the honeycomb body 702 from one of the end faces of the honeycomb body 702 (i.e., the inlet face or the outlet face).
  • a second one of the electrodes 704, designated as electrode 704b, is arranged such that an embedded portion 708 of the electrode 704b is inserted through the outer periphery of the honeycomb body 702 in a direction transverse to the axial direction of the honeycomb body 702, e.g., in the radial direction if the honeycomb body 702 has a circular cross-sectional shape.
  • the electrodes 704 can be inserted in any combination of axial and/or transverse directions, as shown.
  • the conductive ceramic composite material 14a disclosed herein can also be arranged in non-honeycomb configurations.
  • FIGS. 19-21 illustrate various embodiments in which a ceramic body comprising the conductive ceramic composite material 14a is formed with a ceramic body having a spiral or winding shape
  • FIGS. 22A-22B illustrate a ceramic body having a serpentine shape. Since the embodiments of FIGS. 19-22B also comprise the conductive ceramic composite material 14a, the description of the conductive ceramic material 14a given above, such as the properties (e.g., conductivity, porosity, etc.), composition (e.g., silicide phase(s) and carbide phase(s)), method of manufacturing, and so on, are also applicable to FIGS. 19-22B.
  • FIG. 19 shows an aftertreatment device 800 that comprises the conductive ceramic composite material 14a formed into a spiral body 802.
  • opposite ends 804 of the spiral body can be electrically coupled to an electrical power source, e.g., the power source 48 via the leads 40, in order to generate resistive heating within the spiral body 802.
  • FIG. 20 illustrates an aftertreatment system 900 comprising the conductive ceramic composite material 14a formed into a spiral body 902
  • FIG. 21 illustrates an aftertreatment system 1000 comprising the conductive ceramic composite material 14a formed into a spiral body 1002. Similar to the opposite ends 804 of FIG. 19, opposite ends 904 of spiral body 902 and opposite ends 1004 of spiral body
  • the spiral bodies 902, 1002 can be electrically coupled to an electrical power source, e.g., the power source 48 via the leads 40, in order to generate resistive heating within the spiral body 902, 1002.
  • the spiral bodies 902, 1002 are arranged to provide increased surface area, e.g., to carry more catalytic material and/or to increase the rate of heat transfer between the ceramic bodies 902, 1002 and a fluid stream, e.g., vehicle engine exhaust.
  • the ceramic spiral body 902 is arranged so that it is wavy, sinuous, and/or corrugated, while the ceramic spiral body
  • the 1002 comprises a surface texture comprising a plurality of projections 1006 extending outwardly from the sides of the spiral body 1002 along its length between the opposite ends 1004.
  • the projections 1006 in FIG. 21 form pockets 1008 (which further increase surface area without significantly increasing thermal mass), but can alternatively be formed as solid protrusions without such pockets 1008.
  • FIGS. 22A-22B illustrate an aftertreatment system 1100 in which the conductive ceramic composite material 14a is arranged in a ceramic body 1102 having a serpentine shape. Opposite ends 1104 of the serpentine body 1102 can be electrically coupled to a power source, e.g., the power source 48, for generating resistive heating in the material of the serpentine body 1102.
  • the system 1100 can be arranged with a single one of the serpentine bodies 1102; however, in the embodiment of FIGS. 22A-22B, a second ceramic serpentine body, designated with reference numeral 1102', and generally resembling the first ceramic serpentine body 1102, is also included.
  • the second serpentine body 1102’ also comprises opposite ends 1104’ that can be electrically coupled to a power source for generating resistive heating in the material of the serpentine body 1102’.
  • the second ceramic serpentine body 1102' in the illustrated embodiment is rotated with respect to the first serpentine body 1102 (e.g., by 90°) to increase the surface area and/or tortuosity of the flow path through the system 1100, thereby increasing heat transfer with the fluid stream through the system 1100.
  • Any number of serpentine bodies can be sequentially arranged along the fluid flow path to further increase heat generation and surface area for effective heat transfer.
  • Non-honeycomb shapes such as disclosed in FIGS. 19-22B, can be utilized to facilitate electrical coupling between the corresponding conductive ceramic body and a power source.
  • the honeycomb body must be configured to accommodate attachment to and/or engagement with a pair of electrodes to provide the voltage necessary for generating heat.
  • the non-honeycomb shapes can be configured to alleviate the need to attach such electrodes, e.g., the respective opposite ends 804, 904, 1004, and 1104 can effectively act as, and/or integrally form, electrodes for electrically coupling to a power source, such as the power source 48.
  • a first aspect of the disclosure pertains to an electrically conductive honeycomb body.
  • the honeycomb body comprises a porous honeycomb structure comprising a plurality of intersecting porous walls arranged to provide a matrix of cells, the porous walls comprising wall surfaces that define a plurality of channels extending from an inlet end to an outlet end of the structure.
  • the porous walls are comprised of a ceramic composite material that comprises at least one carbide phase and at least one silicide phase, each carbide and silicide phase comprising one or more metal compounds, each metal compound comprising one or more of Si, Mo, Ti, Zr and W. Further, the porous walls have an electrical conductivity that does not decrease upon exposure to 10% steam and 20% oxygen gas at 1000°C for 100 hours.
  • the first aspect is provided, wherein the porous walls further comprise an electrical conductivity that does not decrease upon exposure to 10% steam and 1% oxygen gas at 1000°C for 200 hours.
  • the first or second aspect is provided, wherein the porous walls have an electrical conductivity from about 1 S/cm to about 4000 S/cm.
  • any one of the first through third aspects is provided, wherein the porous walls comprise a median pore size from about 1 pm to about 15 pm.
  • any one of the first through fourth aspects is provided, wherein the porous walls comprise a median porosity from about 35% to about 75%.
  • any one of the first through fifth aspects is provided, wherein the porous walls comprise less than about 0.5 wt.% free silicon metal.
  • any one of the first through sixth aspects is provided, wherein the at least one carbide phase comprises SiC, and the at least one silicide phase comprises MoSi2 and MosST.
  • an aftertreatment system comprising the electrically conductive honeycomb body of any of the first through seventh aspects and an aftertreatment device.
  • a ninth aspect of the disclosure pertains to an electrically conductive honeycomb body.
  • the electrically conductive honeycomb body comprises a porous honeycomb structure comprising a plurality of intersecting porous walls arranged to provide a matrix of cells, the porous walls comprising wall surfaces that define a plurality of channels extending from an inlet end to an outlet end of the structure.
  • the porous walls are comprised of a ceramic composite material that comprises at least one carbide phase and at least one silicide phase, each carbide and silicide phase comprising one or more metal compounds, each metal compound comprising one or more of Si, Mo, Ti, Zr and W.
  • the ceramic composite material is derived in part from a carbon precursor that comprises one or more of a natural carbon source, a graphite source, an amorphous carbon source, and a polyacrylonitrile (PAN) source.
  • the ninth aspect wherein the natural carbon source comprises one or more of a coconut powder, a flour, and a starch, the graphite source comprises one or more of graphite powder and graphite fibers, the amorphous carbon source comprises amorphous carbon fibers, and the PAN source comprises oxidized PAN fibers.
  • the ninth or tenth aspect wherein the porous walls have an electrical conductivity from about 1 S/cm to about 4000 S/cm.
  • any one of the ninth through eleventh aspect is provided, wherein the porous walls comprise a median pore size from about 1 pm to about 15 pm.
  • the porous walls comprise a median porosity from about 35% to about 75%.
  • the porous walls comprise less than about 0.5 wt.% free silicon metal.
  • any one of the ninth through fourteenth aspects is provided, wherein the at least one carbide phase comprises SiC, and the at least one silicide phase comprises M0S12 and MosSiv
  • an aftertreatment system comprising the electrically conductive honeycomb body of any of the ninth through fifteenth aspects and an aftertreatment device.
  • a seventeenth aspect of the disclosure pertains to a method of making an electrically conductive honeycomb body.
  • the method comprises: mixing a plurality of ingredients together into a mixture, the ingredients comprising (a) a metal powder selected from the group consisting of Mo, Ti, Zr and W metal powder, (b) a silicon (Si) metal powder, (c) a carbon precursor, and (d) a liquid vehicle; extruding the mixture into a green honeycomb body; drying the green honeycomb body in air at a temperature from about 50°C to about 200°C; heat treating the green honeycomb body in an inert atmosphere at a temperature from about 300°C to about 900°C; and firing the green honeycomb body in an inert atmosphere at a temperature from about 1400°C to about 2000°C to form an electrically conductive honeycomb body, the honeycomb body comprising a porous honeycomb structure comprising a plurality of intersecting porous walls arranged to provide a matrix of cells, the porous walls comprising wall surfaces that define
  • the porous walls are comprised of a ceramic composite material that comprises at least one carbide phase and at least one silicide phase, each carbide and silicide phase comprising one or more metals selected from the group consisting of Si, Mo, Ti, Zr and W.
  • the carbon precursor comprises one or more of a natural carbon source, a graphite source, an amorphous carbon source, and a polyacrylonitrile (PAN) source.
  • the seventeenth aspect is provided, wherein the natural carbon source comprises one or more of a coconut powder, a flour, and a starch, the graphite source comprises one or more of graphite powder and graphite fibers, the amorphous carbon source comprises amorphous carbon fibers, and the PAN source comprises oxidized PAN fibers.
  • the natural carbon source comprises one or more of a coconut powder, a flour, and a starch
  • the graphite source comprises one or more of graphite powder and graphite fibers
  • the amorphous carbon source comprises amorphous carbon fibers
  • the PAN source comprises oxidized PAN fibers.
  • the eighteenth aspect is provided, wherein the carbon precursor is carbonized in an inert atmosphere at 800°C or greater prior to the mixing.
  • the carbonizing step is conducted in a gaseous atmosphere comprising one or more of nitrogen, argon and helium
  • the firing step is conducted in a gaseous atmosphere comprising one or more of argon and helium.
  • any one of the seventeenth through twentieth aspects is provided, wherein the at least one carbide phase is SiC, and the at least one silicide phase comprises MoSfi and MosSfi.
  • any one of the seventeenth through twenty-first aspects is provided, wherein the porous walls comprise less than about 0.5 wt.% free silicon metal and have an electrical conductivity from about 1 S/cm to about 4000 S/cm.
  • any one of the seventeenth through twenty- second aspects is provided, wherein the mixture comprises (a) a mole fraction of the metal powder selected from the group consisting of Mo, Ti, Zr and W metal powder from about 0.05 to about 0.5, (b) a mole fraction of the silicon (Si) metal powder from about 0.4 to about 0.8 and (c) a mole fraction of the carbon (C) provided from the carbon precursor from about 0.1 to about 0.5.
  • the mixture comprises (a) a mole fraction of the metal powder selected from the group consisting of Mo, Ti, Zr and W metal powder from about 0.05 to about 0.5, (b) a mole fraction of the silicon (Si) metal powder from about 0.4 to about 0.8 and (c) a mole fraction of the carbon (C) provided from the carbon precursor from about 0.1 to about 0.5.
  • any one of the seventeenth through twenty- third aspects is provided, wherein the porous walls comprise a median pore size from about 1 pm to about 15 pm.
  • any one of the seventeenth through twenty- fourth aspects is provided, wherein the porous walls comprise a median porosity from about 35% to about 75%.
  • any one of the seventeenth through twenty-fifth aspects is provided, wherein the porous walls have an electrical conductivity that does not decrease upon exposure to 10% steam and 20% oxygen gas at 1000°C for 100 hours.
  • any one of the seventeenth through twenty- sixth aspects is provided, wherein the porous walls further comprise an electrical conductivity that does not decrease upon exposure to 10% steam and 1% oxygen gas at 1000°C for 200 hours.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Geometry (AREA)
  • Inorganic Chemistry (AREA)
  • Catalysts (AREA)
  • Filtering Materials (AREA)
  • Exhaust Gas After Treatment (AREA)

Abstract

Corps en nid d'abeilles électroconducteur qui comprend une structure en nid d'abeilles poreuse comprenant une pluralité de parois poreuses se croisant agencées pour fournir une matrice de cellules, les parois poreuses comprenant des surfaces de paroi qui définissent une pluralité de canaux s'étendant d'une extrémité d'entrée à une extrémité de sortie de la structure. Les parois poreuses comprennent un matériau composite céramique qui comprend au moins une phase de carbure et au moins une phase de siliciure, chaque phase de carbure et de siliciure comprenant un ou plusieurs métaux choisis dans le groupe constitué par le Si, le Mo, le Ti, le Zr et le W. En outre, les parois poreuses ont une conductivité électrique qui ne diminue pas lors de l'exposition à 10 % de vapeur et 20 % d'oxygène gazeux à 1 000 °C pendant 100 heures.
PCT/US2021/031529 2020-05-15 2021-05-10 Corps en nid d'abeilles conducteurs ayant une capacité de chauffage par résistance et leurs procédés de fabrication WO2021231269A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080179783A1 (en) * 2007-01-31 2008-07-31 Geo2 Technologies, Inc. Extruded Fibrous Silicon Carbide Substrate and Methods for Producing the Same
US20090155528A1 (en) * 2007-12-13 2009-06-18 Ngk Insulators, Ltd. Silicon carbide-based porous body
US20090155527A1 (en) * 2007-12-13 2009-06-18 Ngk Insulators, Ltd. Silicon carbide-based porous body

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080179783A1 (en) * 2007-01-31 2008-07-31 Geo2 Technologies, Inc. Extruded Fibrous Silicon Carbide Substrate and Methods for Producing the Same
US20090155528A1 (en) * 2007-12-13 2009-06-18 Ngk Insulators, Ltd. Silicon carbide-based porous body
US20090155527A1 (en) * 2007-12-13 2009-06-18 Ngk Insulators, Ltd. Silicon carbide-based porous body

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