Patent Application
20210395154
The present disclosure relates generally to conductive ceramic honeycombs with electrically resistive heating capability, including ceramic honeycombs that are useful in treatment of organic compounds in a flow stream.
Ceramic honeycombs have been utilized extensively in the automotive industry for pollution and emission control.
Accordingly, there is a need for honeycombs that offer improved efficiencies in exhaust treatment, along with methods of making these honeycombs.
An aspect of the disclosure pertains to a conductive ceramic 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 metals selected from the group consisting of Si, Mo, Ti, Zr and W.
An aspect of the disclosure pertains to a method of making a conductive ceramic honeycomb 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 from about 50° C. to about 200° C.; carbonizing the green honeycomb body in an inert atmosphere from about 300° C. to about 900° C.; and firing the green honeycomb body in an inert atmosphere from about 1400° C. to about 1800° C. to form an electrically conductive honeycomb body, the honeycomb body 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. Further, 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.
According to aspects of these disclosures, the porous walls of the honeycomb body have an electrical conductivity from about 1 S/cm to about 5000 S/cm. The porous walls can comprise a median pore size from about 1 μm to about 10 μm. The porous walls can also comprise a median porosity from about 35% to about 70%. The porous walls may also have a pore volume from about 0.1 ml/g to about 0.5 ml/g. In addition, the porous walls can be substantially devoid of free metals, and in particular, free silicon metal. By “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), or more preferably less than 0.1 wt %. In some embodiments, the composition comprises essentially none of the specified material, or is even devoid of the specified material (e.g., the porous walls preferably contain essentially no free silicon metal, and more preferably contain no free silicon metal).
Additional features and advantages will be set forth in the detailed description which follows, and will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understanding the nature and character of the disclosure as it is claimed.
The accompanying drawings are included to provide a further understanding of principles of the disclosure, and are incorporated in, and constitute a part of, this specification. The drawings illustrate one or more embodiment(s) and, together with the description, serve to explain, by way of example, principles and operation of the disclosure. It is to be understood that various features of the disclosure disclosed in this specification and in the drawings can be used in any and all combinations. By way of non-limiting examples, the various features of the disclosure may be combined with one another according to the following aspects.
These and other features, aspects and advantages of the present disclosure are better understood when the following detailed description of the disclosure is read with reference to the accompanying drawings, in which:
In the following detailed description, for purposes of explanation and not limitation, example embodiments disclosing specific details are set forth to provide a thorough understanding of various principles of the present disclosure. However, it will be apparent to one having ordinary skill in the art, having had the benefit of the present disclosure, that the present disclosure may be practiced in other embodiments that depart from the specific details disclosed herein. Moreover, descriptions of well-known devices, methods and materials may be omitted so as not to obscure the description of various principles of the present disclosure. Finally, wherever applicable, like reference numerals refer to like elements.
Directional terms as used herein—for example up, down, right, left, front, back, top, bottom—are made only with reference to the figures as drawn and are not intended to imply absolute orientation.
Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps or operational flow; plain meaning derived from grammatical organization or punctuation; the number or type of embodiments described in the specification.
As used herein, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a “component” includes aspects having two or more such components, unless the context clearly indicates otherwise.
Aspects of the disclosure generally relate to conductive ceramic honeycombs with electrically resistive heating capability that are useful in the removal of compounds from gasoline and diesel engine exhaust, such as carbon dioxide. These ceramic honeycombs 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). Advantageously, 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. Another advantage of these ceramic honeycombs is that they are comprised of ceramic composite materials with very high oxidation resistance, suitable for use in high temperature exhaust streams. For example, embodiments of these ceramic 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.
Aspects of the disclosure are also directed to methods of making these conductive ceramic honeycombs. Notably, 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. In general, however, the methods, do not rely on the use of ceramic materials as precursors. As such, 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 (e.g., in ceramic honeycomb form) are produced according to the methods of the disclosure with high electrical conductivity. Further, the electrical conductivity of these ceramic composites can be controlled by controlling the composition of the metal powder and carbon precursors during the batching and mixing steps of the method.
Gases evolving from gasoline and diesel engines exhaust after combustion can include organic compounds generally considered to be harmful or undesirable. 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. For example, 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 NOx gases to N2 and O2 and CO gas to CO2. The gases evolved from the engine can be hot in temperature and transfer heat to activate the catalyst to catalyze the reactions efficiently. However, there can be a lag in the temperature increase of the catalyst during a cold start of a vehicle resulting in the catalyst not being at the required temperature for catalysis. Consequently, the temperature lag associated with a cold start can cause the escape of harmful exhaust gas compounds into the environment without being catalyzed, e.g., to smaller and harmless gases. To efficiently minimize this early escape of harmful gases from the exhaust, the porous honeycomb structures disclosed herein 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.
Referring to
As shown in
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 are so loaded. In the embodiment of
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. Similarly, the shape and dimensions of the honeycomb body 102 or its features (e.g., cells and walls), 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).
As also shown in
As used herein in connection with the porous honeycomb structure 14 depicted in
In some aspects of the disclosure, 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. In one embodiment, the honeycomb 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. In one embodiment, the cells at the inlet and outlet ends are open, or unplugged. The 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).
In an embodiment of the disclosure, the porous honeycomb structure 14, as depicted in exemplary form in
In another embodiment of the conductive ceramic honeycomb 10 depicted in
In a further implementation of the conductive ceramic honeycomb 10 depicted in
Further, the porous honeycomb structure 14 depicted in
According to another aspect, the porous honeycomb structure 14, as depicted in exemplary form in
According to another implementation, the porous honeycomb structure 14 of the conductive ceramic honeycomb 10 depicted in
Referring again to the conductive ceramic honeycomb 10, and the porous honeycomb structure 14 shown in
In some embodiments, 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 80 or the at least one carbide phase 70. In some embodiments, the ceramic composite 14a comprises essentially no free silicon metal, and in further embodiments the ceramic composite and/or honeycomb structure comprises essentially no free metals. Similar to the above, instead of being included as free metals, any metal in the composite 14a may be in the form of the at least one silicide phase 80 and/or the at least one carbide phase 70. For example, 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.
In some embodiments, the ceramic composite 14a comprises no free silicon metal, and/or no free metals of any kind. In some embodiments, the composite or structure being substantially devoid of 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 ceramic honeycomb body 10, such as increased electrical conductivity and decreased thermal expansion, in comparison to ceramic bodies having free metals therein. That is, oxidation of free metals (e.g., upon exposure to air during use of the ceramic honeycomb body 10), can adversely affect various parameters (e.g., by decreasing thermal shock performance, decreasing electrical conductivity, and/or increasing thermal expansion). For example, 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.
Once again referring to the conductive ceramic honeycomb 10, and the porous honeycomb structure 14 shown in
Referring again to the conductive ceramic honeycomb 10 depicted in
Referring once again to the conductive ceramic honeycomb 10 depicted in
According to some embodiments of the ceramic composite 14a of the ceramic honeycomb 10 depicted in
As noted earlier, the temperature of the conductive ceramic honeycomb 10 depicted in
The voltage and current requirements for the conductive ceramic honeycomb 10 depicted in
where ρ is resistivity in ohm-cm, R is resistance in ohms, A is the area of the conducting surface in cm2 and L, as noted earlier, is the distance between two conducting surfaces in cm.
According to an embodiment of the conductive ceramic honeycomb 10 depicted in
Without being bound by theory, the resistive heating of the conductive ceramic honeycomb 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. Further, the fine dispersion of the silicide phase(s) 80 within the at least one carbide phase 70, as formed in situ, according to some embodiments, ensures that the conductivity of the ceramic composite 14a is high and yields substantially uniform heating capability.
In one embodiment, a sufficient temperature for exhaust remediation can comprise heating the honeycombs 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., 300° C., 400° C., 500° C., 600° C., and 700° C., including all ranges and subranges therebetween. In another embodiment, the sufficient heating temperature can be 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.
In addition, any conductive ceramic honeycombs 10, and other honeycomb structures consistent with the principles of this disclosure, may be incorporated into or used in other appropriate system environments. For example, the honeycombs 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 honeycombs 10, and like-constructed honeycomb structures, can be incorporated into a system configuration where catalytic conversion of some components in the stream is desirable.
According to another embodiment of the disclosure, a method 200 of making a conductive ceramic honeycomb 10 (see also
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 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, 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 150° C.
As also depicted in
According to embodiments of the method 200 of making a conductive ceramic honeycomb 10 depicted in
Referring again to the method 200 of making a conductive ceramic honeycomb 10 depicted in
After the drying and/or curing step 230, the method 200 depicted in
Still referring to the method 200 of making a conductive ceramic honeycomb 10 depicted in
The following examples represent certain non-limiting embodiments of the disclosure.
Various molybdenum-containing and titanium-containing conductive ceramic honeycomb examples (i.e., Examples 1-19) were prepared according to a methods of making conductive ceramic honeycombs, as noted in detail below. Each of the honeycombs is consistent with the conductive ceramic honeycombs 10 of the disclosure (see
As noted below in Table 2, the conductive ceramic honeycombs prepared in these examples were characterized to determine their electrical conductivity (S/cm), skeletal density (g/cc), pore size (μm), porosity (%) and pore volume (ml/g). Further, the mole fractions of the metal (Mo or Ti) precursors, silicon (Si) metal, and carbon (C) provided from the carbon precursors employed to fabricate these conductive ceramic honeycombs are provided in Table 2. In addition, the molybdenum-containing conductive ceramic honeycombs (i.e., Examples 1-17) were characterized using x-ray diffraction (XRD) techniques as understood by those of ordinary skill in the field of the disclosure. The results of this characterization are provided below in Table 3A. Table 3A, in particular, details the weight percentages of the silicide (MoSi2 and Mo5Si3) and carbide phases (SiC) in these conductive ceramic honeycomb structures. Further, the results in Table 3A were used to calculate volume percentages of the silicide and carbide phases in these conductive ceramic honeycomb structures, as listed below in Table 3B, using analytical techniques readily understood by those of ordinary skill in the field of this disclosure.
According to this example, a precursor batch was prepared by mixing the following constituents: 20.82 wt. % Mo powder, 40.95 wt. % Si powder, 7 wt. % MM1-hydroxypropyl methylcellulose A4M and 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) in a polyethylene jar. Following this step, 30.23 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.085:0.570:0.344, as shown below in Tables 2, 3A and 3B. The carbon fraction was calculated from experimentally measured carbon content of the resin by curing the resin at 150° C. in air, followed by carbonization in nitrogen gas at 900° C.
After batching the precursor mixture, the mixture was mulled for about 5 minutes. Next, 2 wt. % water was added to the mixture (as a super-addition) and the mixture was then mulled for an additional 20 minutes. The resulting precursor mixture was then extruded in an extruder into a porous honeycomb structure form. The extruded, green part was dried and cured at 150° C. (e.g., in a Thermo Fisher Scientific Isotemp® heating oven) to crosslink the resin and form a rigid structure. The cured rigid structure was then cut into 2 inch pieces and carbonized at 900° C. under a nitrogen atmosphere and then fired at 1800° C. under an argon atmosphere in a graphite-lined furnace. The resulting conductive ceramic honeycomb was then subjected to the following characterization: mercury porosimetry, strength testing, and XRD analysis. The honeycombs were also subjected to electrical conductivity testing by a four-probe electrical conductivity method using a Keithley® Model 2002 multimeter. The XRD pattern demonstrated the existence of a highly crystalline material with MoSi2, Mo5Si3 and SiC phases. Further, the results of this characterization are provided in Tables 2, 3A and 3B below.
According to this example, a precursor batch was prepared by mixing the following constituents: 22.77 wt. % Mo powder, 40.72 wt. % Si powder, 7 wt. % MM1-hydroxypropyl methylcellulose A4M and 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) in a polyethylene jar. Following this step, 28.51 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.094:0.576:0.330, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 24.67 wt. % Mo powder, 40.46 wt. % Si powder, 7 wt. % MM1-hydroxypropyl methylcellulose A4M and 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) in a polyethylene jar. Following this step, 26.87 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.104:0.581:0.316, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 26.5 wt. % Mo powder, 40.23 wt. % Si powder, 7 wt. % MM1-hydroxypropyl methylcellulose A4M and 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) in a polyethylene jar. Following this step, 25.27 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.113:0.586:0.301, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 28.26 wt. % Mo powder, 40.02 wt. % Si powder, 7 wt. % MMI-hydroxypropyl methylcellulose A4M and 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) in a polyethylene jar. Following this step, 23.72 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.122:0.591:0.287, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 30.0 wt. % Mo powder, 39.78 wt. % Si powder, 7 wt. % MM1-hydroxypropyl methylcellulose A4M and 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) in a polyethylene jar. Following this step, 22.22 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.132:0.596:0.272, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 31.66 wt. % Mo powder, 39.56 wt. % Si powder, 7 wt. % MM1-hydroxypropyl methylcellulose A4M and 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) in a polyethylene jar. Following this step, 20.78 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.141:0.601:0.258, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 33.28 wt. % Mo powder, 39.36 wt. % Si powder, 7 wt. % MM1-hydroxypropyl methylcellulose A4M and 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) in a polyethylene jar. Following this step, 19.36 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.150:0.606:0.244, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 34.86 wt. % Mo powder, 39.16 wt. % Si powder, 7 wt. % MM1-hydroxypropyl methylcellulose A4M and 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) in a polyethylene jar. Following this step, 17.98 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.159:0.611:0.230, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 36.39 wt. % Mo powder, 38.96 wt. % Si powder, 7 wt. % MM1-hydroxypropyl methylcellulose A4M and 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) in a polyethylene jar. Following this step, 16.65 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.169:0.616:0.215, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 38.81 wt. % Mo powder, 38.52 wt. % Si powder, 7 wt. % MM1-hydroxypropyl methylcellulose A4M and 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) in a polyethylene jar. Following this step, 14.67 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.184:0.622:0.194, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 38.52 wt. % Mo powder, 38.94 wt. % Si powder, 7 wt. % MM1-hydroxypropyl methylcellulose A4M and 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) in a polyethylene jar. Following this step, 14.54 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.182:0.627:0.192, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 26.92 wt. % Mo powder, 42.42 wt. % Si powder, 7 wt. % MM1-hydroxypropyl methylcellulose A4M and 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) in a polyethylene jar. Following this step, 25.66 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.111:0.595:0.295, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 26.40 wt. % Mo powder, 43.44 wt. % Si powder, 7 wt. % MM1-hydroxypropyl methylcellulose A4M and 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) in a polyethylene jar. Following this step, 25.16 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.108:0.605:0.287, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 36.71 wt. % Mo powder, 36.43 wt. % Si powder, 7 wt. % MM1-hydroxypropyl methylcellulose A4M, 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) and 5 wt. % polyethylene beads (Microthene FN51000 20 μm particle size PE beads from LyondellBasell Industries Holdings B.V.) in a polyethylene jar. Following this step, 13.86 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.184:0.622:0.194, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 38.40 wt. % Mo powder, 34.10 wt. % Si powder, 7 wt. % MM1-hydroxypropyl methylcellulose A4M, 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) and 5 wt. % polyethylene beads (Microthene FN51000 20 μm particle size PE beads from LyondellBasell Industries Holdings B.V.) in a polyethylene jar. Following this step, 14.5 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.196:0.596:0.207, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 20.60 wt. % Mo powder, 36.52 wt. % Si powder, 7 wt. % MM1-hydroxypropyl methylcellulose A4M, 1 wt % sodium stearate (LIGA SS3 SG3 sodium stearate from Peter Greven GmbH & Co.) and 5 wt. % polyethylene beads (Microthene FN51000 20 μm particle size PE beads from LyondellBasell Industries Holdings B.V.) in a polyethylene jar. Following this step, 29.88 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Mo:Si:C for this precursor batch was 0.090:0.545:0.365, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 28.2 wt. % Ti powder, 47.4 wt. % Si powder, 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. Following this step, 17.5 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Ti:Si:C for this precursor batch was 0.200:0.610:0.190, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
According to this example, a precursor batch was prepared by mixing the following constituents: 46.3 wt. % Ti powder, 34.4 wt. % Si powder, 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. Following this step, 12.2 wt. % phenolic resin (GP® 510D50 from Georgia Pacific Chemicals) was added to the mixture and mixed in a separate polyethylene jar. Accordingly, the mole fraction ratio of Ti:Si:C for this precursor batch was 0.380:0.480:0.140, as shown below in Tables 2, 3A and 3B. Further, the resulting precursor was converted into a conductive ceramic honeycomb according to the method outlined above for Example 1. Characterization of the resulting honeycombs was also according to the techniques outlined above for Example 1, with results listed in Tables 2, 3A and 3B.
Referring now to
Referring to
Referring now to
The conductive ceramic materials disclosed herein can be formed into heating elements having a various of shapes. For example,
The conductive ceramic composite material 14a disclosed herein can also be arranged in non-honeycomb configurations. For example,
Non-honeycomb shapes, such as disclosed in
As outlined herein, a first aspect of 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 metals selected from the group consisting of Si, Mo, Ti, Zr and W.
According to a second aspect, the first aspect is provided, wherein the porous walls have an electrical conductivity from about 1 S/cm to about 5000 S/cm.
According to a third aspect, the first or second aspect is provided, wherein the porous walls comprises a median pore size from about 1 μm to about 10 μm.
According to a fourth aspect, any of the first through third aspects is provided, wherein the porous walls comprise a median porosity from about 35% to about 70%.
According to a fifth aspect, any of the first through fourth aspects is provided, wherein the porous walls comprise a median pore volume from about 0.1 ml/g to about 0.5 ml/g.
According to a sixth aspect, any of the first through fifth aspects is provided, wherein the porous walls comprise less than about 0.5 wt % of free silicon metal.
According to a seventh aspect, any of the first through sixth aspects is provided, wherein the porous walls comprise essentially no free silicon metal.
According to an eighth aspect, any of the first through seventh aspects is provided, wherein the porous walls comprise less than about 0.5 wt % of free metal.
According to a ninth aspect, any of the first through eighth aspects is provided, wherein the porous walls comprise essentially no free metal.
According to a tenth aspect, any of the first through ninth aspects is provided, wherein the at least one carbide phase is SiC, and the at least one silicide phase is MoSi2 and Mo5Si3.
According to an eleventh aspect, any of the first through tenth aspects is provided, wherein a volume fraction of the at least one carbide phase is from about 45% to about 90% and a volume fraction of the at least one silicide is from about 10% to about 55%, and further wherein the total of the volume fractions of the at least one carbide and the at least one silicide is about 100%.
According to a twelfth aspect, any one of the first through ninth aspects is provided, wherein the at least one silicide phase is a di-silicide and a tri-silicide.
According to a thirteenth aspect, any one of the first through ninth aspects is provided, wherein the at least one carbide phase is SiC, and the at least one silicide phase comprises titanium (Ti) silicide.
According to a fourteenth aspect, a method of making a conductive ceramic honeycomb is provided. 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 batch into a green honeycomb body; drying the green honeycomb body in air from about 50° C. to about 200° C.; carbonizing the green honeycomb body in an inert atmosphere from about 300° C. to about 900° C.; and firing the green honeycomb body in an inert atmosphere from about 1400° C. to about 1800° 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 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 metals selected from the group consisting of Si, Mo, Ti, Zr and W.
According to a fifteenth aspect, the fourteenth aspect is provided, wherein the carbonizing step is conducted in a gaseous atmosphere comprising one or more of nitrogen, argon and helium, and further wherein the firing step is conducted in a gaseous atmosphere comprising one or more of argon and helium.
According to a sixteenth aspect, the fourteenth or the fifteenth aspect is provided, wherein the carbon precursor comprises a thermosetting polymer which is at least partially cured during the drying step.
According to a seventeenth aspect, any one of the fourteenth through the sixteenth aspects is provided, wherein the at least one carbide phase is SiC, and the at least one silicide phase is MoSi2 and Mo5Si3.
According to an eighteenth aspect, any one of the fourteenth through the seventeenth aspects is provided, wherein a volume fraction of the at least one carbide phase is from about 45% to about 90% and a volume fraction of the at least one silicide is from about 10% to about 55%, and further wherein the total of the volume fractions of the at least one carbide and the at least one silicide is about 100%.
According to a nineteenth aspect, any one of the fourteenth through the eighteenth aspects is provided, wherein the at least one silicide phase is a di-silicide and a tri-silicide.
According to a twentieth aspect, any one of the fourteenth through the nineteenth aspects is provided, wherein the porous walls are substantially devoid of free silicon metal and have an electrical conductivity from about 1 S/cm to about 5000 S/cm.
According to a twenty-first aspect, any one of the fourteenth through the twentieth 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.
According to a twenty-second aspect, any one of the fourteenth through the twenty-first aspects is provided, wherein the porous walls comprise a median pore size from about 1 μm to about 10 μm.
According to a twenty-third aspect, any one of the fourteenth through the twenty-second aspects is provided, wherein the porous walls comprise a median porosity from about 35% to about 70%.
Many variations and modifications may be made to the above-described embodiments of the disclosure without departing substantially from the spirit and various principles of the disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.
This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application No. 62/767,694 filed on Nov. 15, 2018, the content of which is incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2019/061482 | 11/14/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62767694 | Nov 2018 | US |
