Cross Reference to Related Application

[0001] This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Serial No. 63/284133 filed on November 30, 2021, the content of which is relied upon and incorporated herein by reference in its entirety.

Field of the Disclosure

[0002] The present disclosure is directed generally to ceramic honeycomb bodies, and more specifically to extrusion dies used to manufacture high-porosity ceramic honeycomb bodies with peripheral strengthening features, and methods thereof.

Background

[0003] Ceramic honeycomb bodies are used in a wide range of applications, including as filters and substrates in emission control systems for various types of vehicles. For example, when the engine of a car or other type of vehicle bums fuel, diesel, or gasoline, its exhaust carries harmful byproducts like hydrocarbons, nitrogen oxides, carbon monoxide, and particulates. Ceramic honeycomb bodies can be incorporated as part of an emission control system associated with such vehicles to remove harsh gases and particulates from the vehicle exhaust.

[0004] In particular, ceramic honeycomb bodies with thousands of parallel channels can be formed into substrates or filters, which can be used to remediate gaseous pollutants or to remove particulate pollutants, respectively. Using an extrusion process, ceramic honeycomb bodies for formation of such substrates and filters may be created from high-temperature, low- expansion materials that can withstand high temperatures and rapid temperature changes. However, due to the thin walls, high porosities, and processes used, the honeycomb bodies must have sufficient green strength for handling during manufacture and isostatic strength after firing for operational use.

[0005] Accordingly, it is desirable to improve the manufacturability and strength of high- porosity ceramic honeycomb bodies. Summary of the Disclosure

[0006] The present disclosure provides extrusion dies and methods of manufacturing ceramic honeycomb bodies using an extrusion die. Specifically, described herein are extrusion dies used to form ceramic honeycomb bodies having peripheral strengthening features, and methods of using such extrusion dies.

[0007] According to a embodiments, an extrusion die configured to extrude a ceramic honeycomb body is provided. The extrusion die comprising: a plurality of feedholes extending into the die body from an inlet face, the plurality of feedholes being configured to receive a batch material; and a plurality of die slots extending into the die body from a discharge face and connecting to the plurality of feedholes, wherein each die slot of the plurality of die slots is configured to discharge the batch material as a green honeycomb body; wherein a first portion of the plurality of die slots correspond to a matrix region of the extrusion die, a second portion of the plurality of die slots correspond to an inner peripheral region of the extrusion die, and a third portion of the plurality of die slots correspond to an outer peripheral region of the extrusion die; wherein the die slots within the matrix region have a first width, the die slots within the inner peripheral region have a second width, , and the die slots within the outer peripheral region have a third width, wherein the second width is greater than the first and third widths.

[0008] In embodiments, the widths of the die slots within the second portion increase from the first width to the second width at an increment.

[0009] In embodiments, the increment is from about 0.1 mil to about 1.0 mil.

[0010] In embodiments, the first width is less than about 5.0 mils and the second width is greater than about 7.0 mils.

[0011] In embodiments, the widths of the die slots within the third portion decrease incrementally from the second width.

[0012] In embodiments, each die slot of the plurality of die slots has a fillet radius, the fillet radius of the plurality of die slots increasing from a first fillet radius within the matrix region of the extrusion die to a second fillet radius within at least one of the inner peripheral region of the extrusion die and the outer peripheral region of the extrusion die.

[0013] In embodiments, the first width of the die slots within the matrix region of the extrusion die is less than about 5.0 mils.

[0014] In embodiments, the die slots within the matrix region of the extrusion die have a constant die slot width. [0015] In embodiments, the fillet radius of the plurality of die slots increases from the first fillet radius to the second fillet radius at a variable fillet increment.

[0016] In embodiments, the variable fillet increment is from about 0.1 mils to about 1.0 mil.

[0017] In embodiments, a method of manufacturing a ceramic honeycomb article is provided. The method comprises extruding a batch mixture through a plurality of die slots of an extrusion die to form a green ceramic honeycomb body, the green ceramic honeycomb body having a plurality of cell channels formed by intersecting cell walls; and drying and firing the green ceramic honeycomb body to form a ceramic honeycomb article; wherein the green ceramic honeycomb body comprises: a matrix region comprising a first portion of the plurality of cell channels formed by intersecting cell walls, the intersecting cell walls having a first web thickness; an inner peripheral region comprising a second portion of the plurality of cell channels formed by intersecting cell walls have a second web thickness; and an outer peripheral region comprising a third portion of the plurality of cell channels formed by interesting cell walls have a third web thickness, wherein the second web thickness is greater than the first web thickness and the third web thickness.

[0018] In embodiments, the intersecting cell walls forming the second portion of the plurality of cell channels within the inner peripheral region increases from the first web thickness to the second web thickness at a web increment.

[0019] In embodiments, the web increment is from about 0. 1 mil to about 1.0 mil.

[0020] In embodiments, the web increment is variable.

[0021] In embodiments, the first web thickness is less than about 5.0 mils and the second web thickness is greater than about 7.0 mils.

[0022] In embodiments, the intersecting cell walls forming the third portion of the plurality of cell channels within the outer peripheral region decrease in thickness from the second web thickness at a web increment.

[0023] In embodiments, the intersecting cell walls forming the plurality of cell channels have a fillet radius, and wherein the the fillet radius of the intersecting cell walls increases from a first fillet radius within the matrix region to a second fillet radius within at least one of the inner peripheral region and the outer peripheral region at a variable fillet increment.

[0024] In embodiments, the intersecting cell walls of the green ceramic honeycomb body have a minimum fillet radius of about 2.0 mils and a maximum fillet radius of about 4.4 mils. [0025] In embodiments, green ceramic honeycomb body has a variable fillet radius-to- web thickness (FTW) ratio of from about 0.1 to about 1.5. [0026] In embodiments, a ceramic honeycomb article manufactured according to the method of any of the preceding paragraphs is provided.

Brief Description of the Drawings

[0027] In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the various embodiments.

[0028] FIG. l is a perspective view of a ceramic honeycomb body showing a first end, a plurality of cell channels formed by intersecting interior walls, and an outer peripheral wall according to the present disclosure.

[0029] FIG. 2A is a perspective view of a ceramic honeycomb body indicating an interior matrix region according to the present disclosure.

[0030] FIG. 2B is a perspective view of a ceramic honeycomb body indicating a strengthened peripheral region surrounding the interior matrix region according to the present disclosure.

[0031] FIG. 2C is a perspective view of a ceramic honeycomb body indicating an inner peripheral region according to the present disclosure.

[0032] FIG. 2D is a perspective view of a ceramic honeycomb body indicating an outer peripheral region according to the present disclosure.

[0033] FIG. 3 is a schematic enlarged top view of a ceramic honeycomb body showing a plurality of cells with fillets formed by intersecting cell walls according to the present disclosure.

[0034] FIG. 4 is an enlarged front view of a portion of a ceramic honeycomb body showing a plurality of cell channels within a matrix region, a peripheral region, and a fillet transition region.

[0035] FIG. 5 is a schematic partial cross-sectional view of a ceramic batch material being extruded through an extrusion die incorporating peripheral strengthening features according to the present disclosure.

[0036] FIG. 6 is a flowchart illustrating a method of manufacturing a ceramic honeycomb body having a peripheral strengthening feature according to the present disclosure.

[0037] FIGS. 7A and 7B are graphs illustrating the extrusion die slot width transition across a peripheral region of two different extrusion dies according to the present disclosure. [0038] FIG. 8 is a graph modeling the cell wall stress as a function of cell wall thickness according to the present disclosure.

[0039] FIG. 9 is a graph comparing the ratio of fillet radius-to-cell wall thickness across a transitional peripheral region of three ceramic honeycomb bodies.

Detailed Description of Embodiments

[0040] The present disclosure provides apparatuses and methods for manufacturing ceramic honeycomb bodies with peripheral strengthening features. More specifically, the apparatuses include an extrusion die designed to impart corresponding peripheral strengthening features to the ceramic honeycomb bodies, where the ceramic honeycomb bodies have a plurality of tiny channels formed by very thin walls and a high surface area.

[0041] As exhaust emission regulations have become more stringent, designs for exhaust components like ceramic honeycomb bodies have trended towards lower cell densities and reduced web thicknesses to provide lower pressure drops and faster catalyst light-off responses (e.g., in the case of substrates containing a catalyst). For example, ultra-high porosity honeycomb bodies with large surface area and/or high catalyst volume are one of the product designs with the potential to meet future ultra-low NOx regulations. However, these thinwalled, high-porosity ceramic honeycomb bodies result in an overall weaker structure and reduced mechanical durability, rendering them less able to withstand the mechanical and thermal stresses of the exhaust system environment. Additionally, these ceramic honeycomb bodies are difficult to subsequently process and handle due to their tendency to crack, chip, break, and possess flow defects. The extrusion dies and extrusion apparatuses described herein address and resolve many of these issues.

[0042] Turning to FIG. 1, a perspective view of a ceramic honeycomb body 100 comprising a first end 102, a plurality of cell channels 104 formed by intersecting interior walls 106, and an outer peripheral skin or wall 108 is illustrated according to the present disclosure. The ceramic honeycomb body 100 can further comprise a second end 110 positioned opposite from the first end 102. In particular embodiments, the plurality of cell channels 104 and intersecting cell walls 106 can extend between the first end 102 and the second end 110 of the honeycomb body 100. The plurality of cell channels 104 can be configured to allow the flow of a fluid such as exhaust from an associated vehicle’s exhaust system. For example, the plurality of cell channels 104 can be a plurality of continuous, uninterrupted, parallel fluidconducting cells oriented along an axis extending from the first end 102 to the second end 110. The first end 102 can be an inlet face that receives a fluid flow into the cell channels 104 of the honeycomb body 100, while the second end 110 can be a discharge face where the fluid flow exits the cell channels 104 of the honeycomb body 100. Accordingly, the plurality of cell channels 104 are not plugged in some embodiments and therefore provide an unobstructed fluid flow from the first end 102 to the second end 110. In alternative embodiments, at least a portion of the plurality of cell channels 104 can be plugged in order to force the fluid stream to flow through the porous ceramic material of the walls 106, thereby arranging the ceramic honeycomb body 100 as a particulate filter or wall-flow filter.

[0043] Turning to FIGS. 2A-2D, and as disclosed further herein, the ceramic honeycomb bodies 100 of the present disclosure can comprise an interior matrix region 120, a peripheral region 130 surrounding the interior matrix region 120, and an outer skin (i.e., an outer wall) 108 surrounding both the peripheral region 130 and matrix region 120. As shown in FIGS. 2C and 2D, the peripheral region 130 can include an inner peripheral region 132 and an outer peripheral region 134. In embodiments, the matrix region 120 comprises a first portion of the plurality of channels 104, the inner peripheral region 132 comprises a second portion of the plurality of channels 104, and the outer peripheral region 134 comprises a third portion of the plurality of channels 104. The first portion of the plurality of channels 104 can be defined by the intersecting cell walls 106 within the matrix region 120, whereas the second and third portions of the plurality of channels 104 can be defined by the intersecting cell walls 106 within the inner and outer peripheral regions 132, 134, respectively.

[0044] In still further embodiments, the plurality of cell channels 104 can comprise a catalyst that promote chemical reactions that convert one or more undesirable compounds (e.g., CO, NO _X , and hydrocarbons) into non-polluting compounds such as H2O, O2, and N2. For example, in some embodiments, at least a portion of the plurality of cell channels 104 comprise a catalyst coating deposited on surfaces therein (i.e., the intersecting cell walls 106 forming the at least a portion of the plurality of cell channels 104 are coated with a catalyst material). In other embodiments, at least a portion of the porous ceramic material of the intersecting cell walls 106 that form one or more of the plurality of cell channels 104 is impregnated with a catalyst material. The catalyst can comprise, for example, and without limitation, a precious metal such as platinum, rhodium, palladium, as well as alumina or other catalyst materials, and combinations thereof.

[0045] The ceramic honeycomb body 100 can be formed by extruding a batch mixture through an extrusion die of an extrusion apparatus as described below. For example, the batch mixture used to form the ceramic honeycomb body 100 can comprise one or more inorganic ceramic or ceramic precursor particles, such as alumina, silica, titania, magnesia, clay, talc, cordierite, mullite, silicon carbide, aluminum titanate, and combinations thereof. The batch mixture can additionally comprise a liquid vehicle such as water, an organic binder such as methylcellulose, a pore former such as starch, polymer particles, or graphite, and a lubricant such as an oil or fatty acid, in addition to other additives or ingredients to influence the final properties of the ceramic honeycomb body 100 and/or assist in one or more manufacturing steps.

[0046] The ceramic honeycomb bodies 100 of the present disclosure can be high-porosity honeycomb bodies, such as having an overall porosity of at least about 50%, at least 55%, or even at least about 60%, such as from about 60% to about 70%, and any combination of endpoints thereof.

[0047] In further embodiments, the porosity of the matrix region 120 and the porosity of the peripheral region 130 can be different or the same. For example, the porosity of the matrix region 120 can be greater than, less than, or equal to the porosity of the peripheral region 130. In specific embodiments, the porosity of the matrix region 120 and the porosity of the peripheral region 130 can independently be from about 60% to about 70%, and any combination of endpoints thereof.

[0048] Although not limited to a particular geometry, the honeycomb body 100 can be cylindrical with a cylindrical matrix region 120 having a diameter (D) of from about 4 inches to about 13 inches, including from about 4 inches to about 8 inches and from about 8 inches to about 13 inches. Further, the peripheral region 130 can be cylindrical and the inner and outer peripheral regions 132, 134 can have width Wi and W2 respectively, such that the peripheral region 130 has a width (W) of from about 0.2 inches to about 1.5 inches, including from about 0.2 inches to about 0.5 inches and from about 0.5 inches to about 1.5 inches. In specific embodiments, the diameter (D) of the matrix region 120 can be about 12 inches and the width (W) of the peripheral region 130 can be about 0.85 inches. In further embodiments, the outer skin 108 can be cylindrical with a thickness of from about 5 mils to about 50 mils.

[0049] Although also not limited to a particular geometry, the intersecting cell walls 106 can have a thickness (which may be referred to as a web thickness or a wall thickess) of from about 2 mils to about 9 mils, including from about 2 mils to about 4 mils, from about 4 mils to about 6 mils, from about 6 mils to about 9 mils, and any combination of endpoints thereof. In embodiments, the thickenss of the walls 106 in the matrix region 120 is different from the thickness of the walls 106 in the peripherial region 130. In embodiments, the web thickness of the intersecting cell walls 106 within the matrix region 120 is less than about 6 mils, including less than about 5 mils. In embodiments, the web thickness of the intersecting cell walls 106 within the peripheral region 130 is greater than that of the thickness of the walls 106 in the matrix region, such as greater than 5 mils, including greater than about 6 mils, greater than about 7 mils, and greater than about 8 mils. In specific embodiments, the web thickness of the intersecting cell walls 106 within the matrix region 120 is less than the web thickness of the intersecting cell walls 106 within the peripheral region 130. As described herein, at least some of the walls in the inner peripheral region 132 can be the maximum thickness for all of the walls in the ceramic honeycomb body 100. Thus, the maximum thickness of the walls in the inner peripheral region 132 can be larger than the maximum thicknesses of the walls in either the matrix region 120 or the outer peripheral region 134.

[0050] According to further aspects of the present disclosure, the web thicknesses of the intersecting cell walls 106 can be of a constant thickness or can have a variable web thickness. In particular, the matrix region can comprise a plurality of cell channels 104 formed by intersecting cell walls 106 having a first web thickness, the inner peripheral region 132 can comprise a plurality of cell channels 104 formed by intersecting cell walls 106 having a web thickness that increases from a second web thickness to a third web thickness, and the outer peripheral region 134 can comprise a plurality of cell channels 104 formed by intersecting cell walls 106 having a web thickness that decreases from a fourth web thickness to a fifth web thickness. For example, the web thickness of the intersecting cell walls 106 within the inner peripheral region 132 can increase when moving away from matrix region 120 and towards the outer skin 108.

[0051] In some aspects, the web thickness of the intersecting cell walls 106 within the inner peripheral region 132 can increase by the same amount between each set of adjacent cell channels 104 or may increase at a variable increment / rate. For example, the web thickness of the intersecting cell walls 106 within the inner peripheral region 132 can increase from the second web thickness to a third web thickness at a variable web increment / rate of from about 0.1 mils to about 1.0 mils, including about 0.1 mils, about 0.2 mils, about 0.3 mils, about 0.4 mils, about 0.5 mils, about 0.6 mils, about 0.7 mils, about 0.8 mils, about 0.9 mils, and about 1.0 mils. More specifically, the intersecting cell walls 106 within the inner peripheral region 132 can have a variable web increment / rate with a minimum of at least about 0.3 mils and a maximum of at least about 0.8 mils. In further aspects, the intersecting cell walls 106 within the inner peripheral region 132 can remain constant at the third web thickness for one or more pairs of adjacent cell channels 104, as shown with respect to FIG. 7B. [0052] In other aspects, the web thickness of the intersecting cell walls 106 within the outer peripheral region 134 can decrease by the same amount between each set of adjacent cell channels 104 or may decrease at a variable increment / rate. For example, the web thickness of the intersecting cell walls 106 within the outer peripheral region 134 can decrease at a variable web increment / rate of from about 0. 1 mils to about 1.0 mils, including about 0.1 mils, about 0.2 mils, about 0.3 mils, about 0.4 mils, about 0.5 mils, about 0.6 mils, about 0.7 mils, about 0.8 mils, about 0.9 mils, and about 1.0 mils. In further aspects, the intersecting cell walls 106 within the outer peripheral region 134 can remain constant at the fifth web thickness for one or more pairs of adjacent cell channels 104, as shown with respect to FIG. 7B.

[0053] Turning now to FIG. 3, an enlarged view of a portion of a ceramic honeycomb body 300 is depicted in accordance with still further aspects of the present disclosure. In particular embodiments, one or more of the plurality of cell channels (e.g., cell channels 104) can be filleted or unfilleted. For example, cell channel 304A seen in FIG. 3 is unfilleted whereas cell channels 304B, 304C, and 304D are filleted to different degrees. Each of the filleted cell channels 304B, 304C, 304D can have a fillet radius, which refers to the circularity of the channels 304B, 304C, 304D are rounded. As shown, cell channel 304B has a fillet radius Ri, cell channel 304C has a fillet radius of R2, and cell channel 304D has a fillet radius of R3, wherein Ri > R2 > R3. By increasing the fillet radius, it has the effect of decreasing the area of the channels 304B, 304C, 304D and increasing the cell wall thickness 305B, 305C, 305D around the comers of the channels 304B, 304C, 304D. In particular embodiments, the fillet radius (e.g., radii Ri, R2, R3) can be from about 2.0 mils to about 4.4 mils, and any combination of endpoints thereof.

[0054] Furthermore, the fillet radii of the ceramic honeycomb bodies 100 disclosed herein can be independently selected. For example, the ceramic honeycomb bodies described herein can comprise a fillet transition region wherein the fillet radii of the plurality of cell channels varies between one or more adjacent cell channels. With specific reference to FIG. 4, an enlarged portion of a honeycomb body 400 is illustrated comprising a plurality of cell channels 404 formed by intersecting cell walls 406. As discussed above, the honeycomb body 400 can comprise a matrix region 420 comprising a first portion of the plurality of cell channels 404 and a peripheral region 430 having an inner and outer peripheral region comprising a second and third portion of the plurality of cell channels 404. As shown, the honeycomb body 400 can further comprise a fillet transition region 440. In aspects, the fillet transition region 440 can overlap a portion of the matrix region 420 and the peripheral regions 430, such as the inner peripheral region or the inner and outer peripheral regions. In other words, the fillet transition region 440 can comprise a portion of the matrix region 420 and a portion of the peripheral regions 430. Accordingly, portions of the fdlet transition region 440 can have constant web thickness and/or variable web thicknesses, as discussed above.

[0055] More specifically, within the fillet transition region 440, the fillet radii of the intersecting cell walls 406 forming the plurality of cell channels 404 can transition from a first fillet radius within the matrix region to a second fillet radius within at least one of the inner and outer peripheral regions. In aspects, the fillet radius of the intersecting cell walls 406 can increase from the first fillet radius to the second fillet radius at a variable fillet increment. For example, the first fillet radius can be about 2.0 mils, the second fillet radius can be about 4.4 mils, and the fillet radii of the intersecting cell walls 406 forming the plurality of cell channels 404 transitions from 2.0 mils to 4.4 mils in incremental steps within the fillet transition region 440. In some embodiments, the fillet radii of the intersecting cell walls 406 within the fillet transition region 440 can transition from the first fillet radius to a second fillet radius by about 0.2 mils, about 0.3 mils, about 0.4 mils, about 0.5 mils, about 0.6 mils, about 0.7 mils, about 0.8 mils, about 0.9 mils, about 1.0 mils.

[0056] According to further aspects of the present disclosure, the matrix region 420 and the peripheral regions 430 the ceramic honeycomb body 400 can have a defined fillet-to-web thickness (FTW) ratio. In particular embodiments, the FTW ratio of the matrix region 420 can be from about 0.5 to about 1.5. In specific embodiments, the maximum FTW ratio within the matrix region is no more than about 1.5, including no more than about 1.25 and no more than about 1. In other embodiments, the FTW ratio of the peripheral regions 430 can also be from about 0.5 to about 1.5. In specific embodiments, the maximum FTW ratio within the peripheral regions 430 is no more than 1.5, including no more than about 1.25 and no more than about 1. Additionally, as discussed below with respect to FIG. 9, the maximum differential in the FTW ratio between any two adjacent cell channels 404 is less than or equal to about 0.25, including less than about 0.25, less than about 0.2, less than about 0.15, and less than about 0.1. In specific embodiments, the FTW ratio does not vary (i.e., is consistent) within a particular region of the honeycomb body, such as the matrix region, while the FTW ratio varies within another region of the honeycomb body, such as the peripheral region(s) and/or the fillet transition region.

[0057] Additionally, the ceramic honeycomb bodies 400 of the present disclosure can have a stress amplification factor that indicates a lower propensity for cracking during firing of the honeycomb body 400. For example, in particular embodiments, the honeycomb body 400 can have a stress amplification factor of at most about 1.75, including about 1.75, about 1.74, about 1.73, about 1.72, about 1.71, about 1.7, about 1.69, about 1.68, about 1.67, about 1.66, about 1.65, about 1.64, about 1.63, about 1.62, about 1.61, about 1.6, about 1.59, about 1.58, about 1.57, about 1.56, about 1.55, about 1.54, about 1.53, about 1.52, about 1.51, about 1.5, about 1.49, about 1.48, about 1.47, about 1.46, about 1.45, about 1.44, about 1.43, about 1.42, about 1.41, about 1.4, about 1.39, about 1.38, about 1.37, about 1.36, about 1.35, about 1.34, about 1.33, about 1.32, about 1.31, about 1.3, about 1.29, about 1.28, about 1.27, about 1.26, about 1.25, about 1.24, about 1.23, about 1.22, about 1.21, about 1.2, about 1.19, about 1.18, about 1.17, about 1.16, about 1.15, about 1.14, about 1.13, about 1.12, about 1.11, about 1.1, about 1.09, about 1.08, about 1.07, about 1.06, about 1.05, about 1.04, about 1.03, about 1.02, about 1.01, about 1, and ranges formed from such endpoints. As used herein, the term stress amplification factor refers to the ratio of the maximum vertical stress in the fillet region to the maximum vertical stress in the web.

[0058] As shown in Table 3, the firing performance of Examples 3, 4, and 5 are shown in terms of the respective stress amplification factors. Example 3 with a step-change in fillet radius exhibits a stress riser and consequently the highest stress amplification factor, whereas Examples 4 and 5 exhibited lower stress amplification factors and consequently will have lower cracking propensity. As used herein, the term stress amplification factor refers to the ratio of the maximum vertical stress in the fillet region to the maximum vertical stress in the web. As such, a lower stress amplification factor indicates a lower propensity for cracking during firing. [0059] Turning now to FIG. 5, a cross-section of an extrusion die 500 configured to extrude a ceramic honeycomb body (e.g., honeycomb body 100) with peripheral strengthening features is illustrated in accordance with the present disclosure. The extrusion die 500 comprises a die body 512 provided with feedholes 514 that extend into the die body 512 from an inlet face 510, from which a batch material 516 is introduced into the die body 512. In other words, the inlet face 510 can be configured to receive the batch material 516 via a plurality of feedholes 514. Connecting with the feedholes 514 are a plurality of die slots 518, 519 terminating at a discharge face 520 of the die body 512 from which the batch material 516 is extruded in the form of a green honeycomb extrudate 530. The extruded green honeycomb body 530 can comprise an outer extruded skin 536 surrounding the body 530 and the intersecting cell walls 532. For example, the honeycomb extrudate 530 can be cut to length to form the honeycomb body 100.

[0060] As mentioned above, the honeycomb extrudate 530 can comprise a matrix region with thin intersecting cell walls 532 having a first maximum web thickness, an inner peripheral region with intersecting cell walls 533 having a second maximum web thickness, and an outer peripheral region with intersecting cell walls 534 having a third maximum web thickness, where the second maximum web thickness of the walls 533 is greater than the first and second web thicknesses of the intersecting cell walls 532, 534 within the matrix region and the outer peripheral region, respectively. In embodiments, the third maximum web thickness is wider than the first maximum web thickness. The honeycomb extrudate 530 can also comprise a fillet transition region that overlaps at least a portion of the matrix region and the peripheral region(s) as described herein.

[0061] Accordingly, the extrusion die 500 comprise a corresponding matrix region having narrow die slots 517 of a first slot width (corresponding to the first web thickness), an inner peripheral region having die slots 518 of a second slot width (corresponding to the second web thickness), and an outer peripheral region comprising die slots 519 of a third slot width (corresponding to the third web thickness), where the second slot width is the widest slot width in the die 500 (which correspondingly results in the second web thickness of the walls 533 in the inner peripherial region also being the widest) . As such, the cell channels 538 within each of the matrix region, inner peripheral region, the outer peripheral region, and/or fillet transition region can correspond to one or more portions of the plurality of die slots 518, 519.

[0062] More specifically, the extrusion die 500 can comprise a plurality of die slots where a first portion of the plurality of die slots correspond to a matrix region of the extrusion die 500, a second portion of the plurality of die slots correspond to an inner peripheral region of the extrusion die 500, and a third portion of the plurality of die slots correspond to an outer peripheral region of the extrusion die 500.

[0063] In aspects, the honeycomb extrudate 530 can include about 600 cell channels 538 per square inch of the honeycomb body. In some embodiments, the honeycomb body 530 can be cylindrical and include a plurality of layers of adjacent cell channels 538 that correspond to layers of adjacent die slots 517, 518, 519 of an extrusion die 500. For example, the peripheral region (i.e., the inner and outer peripheral regions) of the honeycomb body 530 can comprise from about 5 to about 50, such as from about 10 to about 20 layers of adjacent cell channels 538 (although only a few shown in FIG. 5 for clarity) and the portion of the plurality of die slots 517, 518, 519 that corresponds to this region can correspondingly comprise from about 5 to about 50, such as from about 10 to about 20 layers of adjacent die slots. Similarly, the fillet transition region of the honeycomb body 530 can comprise from about 2 to about 6 layers of adjacent cell channels 538 and the portion of the plurality of die slots 517, 518, 519 that corresponds to this region can comprise from about 2 to about 6 layers of adjacent die slots.

[0064] Further, each of the die slots 517, 518, 519 can be defined in terms of a die slot width and a fillet radius. When the fillet radius is 0, the channels have perpendicular (square) comers. As such, a first portion of the plurality of die slots 517, that corresponds to a matrix region of the extrusion die 500 can have at least a first die slot width, a second portion of the plurality of die slots 518 that corresponds to an inner peripheral region of the extrusion die 500 can have at least a second die slot width, and a third portion of the plurality of die slots 519 that corresponds to an outer peripheral region of the extrusion die 500 can have at least a third die slot width . Similarly, each of the plurality of die slots 518, 519 can have a fillet radius that increases from a first fillet radius within the matrix region of the extrusion die 500 to a second fillet radius within at least one of the inner peripheral region and/or the outer peripheral region of the extrusion die 500.

[0065] According to further aspects of the present disclosure, the die slot width and/or the fillet radius can vary between die slots of different regions and can vary between die slots within the same region. For example, within each of the matrix, peripheral, and fillet transition regions, the corresponding die slots can have a maximum and minimum die slot width that changes between two or more adjacent die slots as well as a maximum and minimum fillet radius that changes between two or more adjacent die slots. In some embodiments, a portion of the die slots 517, 518, 519 corresponding to one or more of the regions described herein can further include an intermediate width and/or an intermediate fillet radius. For example, the slots 518 in the inner peripheral region can step up to the second slot width in increments from the first slot width of the slots 517 in the matrix region. In other words, the each of the regions described herein can comprise multiple different widths. Accordingly, reference herein to the first slot width, second slot width, third slot width, first web thickness, second web thickness, or third web thickness is generally referring to the maximum value of the associated width or thickness, unless specified otherwise.

[0066] In embodiments, the change in the die slot width between any two adjacent die slots 517, 518, 519, or the width increment, can be from about 0.1 mil to about 1.0 mil. In embodiments, the change in the fillet radius between any two adjacent die slots 517, 518, 519, or the fillet radius increment, can be from about 0.2 mils to about 1.0 mil. In certain embodiments, width ofthe die slots 518, 519 can be from about 4.0 mils to about 8.2 mils, and any combination of endpoints thereof.

[0067] In embodiments, the width of the die slots 517 corresponding to the matrix region is less than or equal to about 4.0 mils. In further embodiments, as mentioned above, the width of the die slots 518, 519 corresponding to a peripheral region(s) can increase at a variable rate (or increment) when moving from the matrix region towards the outer skin 536. For example, the width of the die slots 518 closest to the matrix region can be about 4 mils, which then increases by at least 0.4 mils between adjacent cell channels 538. In some embodiments, the width of the die slots 518 can increase until it reaches a maximum die slot width closest to the boundary or transition between the inner peripheral region and the outer peripheral region. For example, the width of the die slots 518 can increase until it reaches a maximum die slot width of 8 mils or more. The width of the die slots 519 in the outer peripheral region can decrease to one or more intermediate die slot widths between the inner peripheral region and the outer skin 536. For example, the width of the die slots 519 corresponding to the outer peripheral region can decrease from the maximum in the inner peripheral region to an intermediate die slot width of about 7 mils or less.

[0068] Additionally, as mentioned above, the honeycomb extrudate 530 can comprise a fdlet transition region (e.g., fdlet transition region 440). Accordingly, the extrusion die 500 can have die slots 517, 518, 519 configured to extrude intersecting cell walls 532, 533, 534 with rounded comers of different fillet radii. More specifically, the extrusion die 500 can comprise one or more die slots 517 within a portion of the die 500 that correspond to the matrix region of the honeycomb extrudate 530, one or more die slots 518 within a portion of the die 500 that correspond to the inner peripheral region of the honeycomb extrudate 530, and one or more die slots 519 that correspond to the outer peripheral region of the honeycomb extrudate 530.

[0069] With reference to FIG. 6, also provided herein are methods 600 of manufacturing a ceramic honeycomb article having peripheral strengthening features. The method 600 begins at step 610. At a step 620, the method 600 comprises extruding a batch mixture through a plurality of die slots of an extrusion die to form a green ceramic honeycomb body (i.e., a wet or unfired ceramic honeycomb structure). The green ceramic honeycomb body can comprise a plurality of cell channels formed by intersecting cell walls, and an outer skin surrounding the plurality of cell channels. The green ceramic honeycomb body can further comprise an interior matrix region comprising a first portion of the plurality of cell channels, an inner peripheral region comprising a second portion of the plurality of cell channels, and an outer peripheral region comprising a third portion of the plurality of cell channels.

[0070] At a step 630, the method 600 comprises drying and firing the green ceramic honeycomb body as known in the art to form a dry ceramic honeycomb body. In accordance with the various aspects of the present disclosure, the die slots of the extrusion die corresponding to the matrix region, an inner peripheral region, an outer peripheral region, and optionally fillet transition region can be embodied as discussed above. That is, the die slots of the extrusion die can be configured to extrude the batch material such that the dry honeycomb body comprises a matrix region, an inner peripheral region, an outer peripheral region, and a fillet transition region as described herein.

[0071] In particular embodiments, the method 600 further comprises a step 640, wherein the dry honeycomb body is contoured to form a ceramic honeycomb article. More specifically, the step 640 includes removing one or more outer channels from the peripheral region of the dry ceramic honeycomb body to form the ceramic honeycomb article. For example, the walls and channels corresponding to the outer peripheral can be removed in some embodiments, such that the resulting honeycomb body comprise only the matrix region and the inner peripheral region after the removal process. A cement or other material can be applied to the remaining honeycomb structure to form the outer skin 108 if the outer peripheral region of the honeycomb body is removed. Optionally, the method 600 can also comprise plugging one or more of the cell channels of the dry honeycomb body to form a filter, or subjected to a catalyst wash coat in order to impregnate the walls of the cells with a catalyst, as mentioned above. Thus, the ceramic honeycomb article can be, for example, and without limitation, a filter or a substrate used in the exhaust emission system, including a catalytic converter substrate.

EXAMPLES

[0072] With reference to FIGS. 7A and 7B, two extrusion die designs are graphically illustrated. The portions of the extrusion dies represented in the graphs shown in FIGS. 7A and 7B correspond to the peripheral regions of the ceramic honeycomb body. That is, the portion of the extrusion die that forms the peripheral regions of the ceramic honeycomb body is depicted in accordance with certain aspects of the present disclosure. As shown, both the first and second examples comprise a plurality of die slots corresponding to the cell channels of the peripheral regions. In the first example, the die slot widths are shown increasing from a minimum die slot width to a maximum die slot width, which is then maintained for a plurality of channel-forming die slots. In the second example, the die slot widths are shown increasing from a minimum die slot width to a maximum die slot width, and then decreasing to an intermediate die slot width, which is then maintained for a plurality of channel-forming die slots. However, in both examples, the increments between adjacent channel-forming slots begin small, but increases between each subsequent pair of adjacent cells. The specific die slot widths and increments (A) for both examples are shown in Table 1 below: TABLE 1

Cell Example 1 Example 2

Number Die Slot Width (inches) A Die Slot Width (inches) A

1 0.004 0.004

2 0.0044 0.000 0.0044 0.0004

3 0.0049 0.000 0.0049 0.0005

4 0.0055 0.000 0.0055 0.0006

5 0.0061 0.000 0.0061 0.0006

6 0.0068 0.000 0.0068 0.0007

7 0.0075 0.000 0.0075 0.0007

8 0.0082 0.000 0.0082 0.0007

9 0.0082 0 0.0082 0

10 0.0082 0 0.0082 0

11 0.0082 0 0.0076 -0.0006

12 0.0082 0 0.0071 -0.0005

13 0.0082 0 0.0071 0

14 0.0082 0 0.0071 0

15 0.0082 0 0.0071 0

16 0.0082 0 0.0071 0

17 0.0082 0 0.0071 0

18 0.0082 0 0.0071 0

19 0.0082 0 0.0071 0

20 0.0082 0 0.0071 0

[0073] Additionally, as shown in Table 1, the peripheral regions of the honeycomb body have about 20 adjacent cell channels, which correspond to individual die slots of varying widths.

[0074] With reference to FIG. 8, a graph modeling the web stress as a function of the web thickness within the peripheral regions are illustrated, which shows that as the web thickness increases within the peripheral regions, the web stress decreases. In particular, FIG. 8 illustrates that a web thickness of about 7.1 mils within the peripheral regions of a honeycomb body is the optimal thickness for achieving strengths necessary to avoid defects caused in the articles due to the handling process.

[0075] With reference to FIG. 9, three examples of transitions between the matrix region of a honeycomb body and the peripheral regions of a honeycomb body are illustrated graphically with the Y -axis showing the ratio of the fillet radius to the web thickness (i.e ., FTW ratio). As shown, Examples 4 and 5 have a gradual transition in the FTW ratio between their respective matrix regions and peripheral regions, whereas Example 3 has a large step change in the FTW ratio corresponding to a sudden increase in the fillet radius. The fillet radii and the resulting performance of these three examples are shown below in Tables 2 and 3 respectively:

TABLE 2

Fillet Radius (mils)

Location Example 3 Example 4 Example 5

Matrix- 1 2.0 2.0 2.0 Matrix-2 2.0 2.6 2.8 Matrix-3 4.4 2.9 3.6 Periphery- 1 4.4 3.6 4.4 Periphery-2 4.4 4.0 4.4 Periphery-3 4.4 4.4 4.4 Periphery-4 4.4 4.4 4.4 Periphery-5 4.4 4.4 4.4 Periphery-6 4.4 4.4 4.4 Periphery-7 4.4 4.4 4.4 Periphery-8 4.4 4.4 4.4 Periphery-9 4.4 4.4 4.4 Periphery- 10 4.4 4.4 4.4 Periphery- 11 4.4 4.4 4.4 Periphery- 12 4.4 4.4 4.4 Periphery- 13 4.4 4.4 4.4 Periphery- 14 4.4 4.4 4.4 Periphery- 15 4.4 4.4 4.4 Periphery- 16 4.4 4.4 4.4 Periphery- 17 4.4 4.4 4.4 Periphery- 18 4.4 4.4 4.4

TABLE 3

Maximum Fillet Maximum Web . >.... , .

Stress (MPa) Stress (MPa) Amplification

Example 3 14.70 9.84 1.49

Example 4 13.09 9.3 1.41

Example s 13.27 9.35 1.42

[0076] As shown in Table 3, the firing performance of Examples 3, 4, and 5 are shown in terms of the respective stress amplification factors. Example 3 with a step-change in fillet radius exhibits a stress riser and consequently the highest stress amplification factor, whereas Examples 4 and 5 exhibited lower stress amplification factors and consequently will have lower cracking propensity. As mentioned above, the term stress amplification factor refers to the ratio of the maximum vertical stress in the fillet region to the maximum vertical stress in the web. As such, a lower stress amplification factor indicates a lower propensity for cracking during firing.

[0077] In accordance with these and other aspects of the present disclosure, the extrusion dies and ceramic honeycomb bodies described herein address the manufacturing and performance challenges presented by the ultra-high porosity products, significantly reduce the risk of defects in the forming and firing process steps that are necessary to make the final ceramic honeycomb product, reduce the time needed to manufacture the extrusion die by over 33%, and improves the differential flow in extrusion.

[0078] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms.

[0079] The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” [0080] The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements can optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. [0081] As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also comprising more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of’ or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” [0082] As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily comprising at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements can optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified.

[0083] It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited.

[0084] In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of’ and “consisting essentially of’ shall be closed or semi-closed transitional phrases, respectively.

[0085] The above-described examples of the described subject matter can be implemented in any of numerous ways. For example, some aspects can be implemented using hardware, software or a combination thereof. When any aspect is implemented at least in part in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single device or computer or distributed among multiple devices/computers .

[0086] While various examples have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the examples described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific examples described herein. It is, therefore, to be understood that the foregoing examples are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, examples can be practiced otherwise than as specifically described and claimed. Examples of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the scope of the present disclosure.