Ceramic honeycomb structure, honeycomb extrusion die, and method for manufacturing ceramic honeycomb structure
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2016-08-24
- Publication Date
- 2026-08-14
Smart Images
Figure CN122560211A_ABST
Abstract
Description
[0001] Cross-reference of related applications
[0002] This application claims priority to U.S. Provisional Application No. 62 / 211,981, filed August 31, 2015, the contents of which are incorporated herein by reference in their entirety. background Technical Field
[0003] The exemplary embodiments disclosed herein relate to ceramic honeycombs.
[0004] Background Discussion
[0005] Ceramic wall-flow filters can be used to remove particulate contaminants from fluid streams, such as diesel, gasoline, or other internal combustion engine exhaust streams. There are many different methods for manufacturing such filters using a honeycomb structure with channels formed from porous ceramics. For example, one method involves placing a solidified plug formed from a sealing material at the ends of the alternating channels of this structure. This blocks direct fluid flow through the channels and forces the fluid flow to pass through the porous channel walls of the honeycomb before exiting the filter.
[0006] The information disclosed in the background section is only intended to enhance the understanding of the technical background of the claimed invention, and therefore may contain information that does not constitute any part of the prior art or that the prior art may not be enlightening to those skilled in the art. Summary of the Invention
[0007] Exemplary embodiments of this disclosure provide a honeycomb structure comprising a layered surface.
[0008] Exemplary embodiments of this disclosure also provide a method for manufacturing a honeycomb structure comprising a layered surface.
[0009] Exemplary embodiments of this disclosure also provide an extrusion die configured to extrude a batch of ceramic precursor material into a green honeycomb containing a layered surface.
[0010] Other features of the invention will be set forth in the following description, and in part will be apparent from the description or may be learned from practice of the claimed invention.
[0011] An exemplary embodiment discloses a green honeycomb body comprising a cross-wall matrix forming channels extending axially from a first end face to a second end face; and a layered surface layer disposed on the outer periphery of the matrix, extending from the first end face to the second end face. A large portion of the cross-sectional area of the layered surface layer contains axially aligned particles that are substantially the same as those of the cross-wall matrix.
[0012] An exemplary embodiment also discloses a porous ceramic honeycomb comprising a cross-wall matrix forming channels extending axially from a first end face to a second end face; and a layered surface layer disposed on the outer periphery of the matrix, the outer periphery extending from the first end face to the second end face. A large portion of the cross-sectional area of the layered surface crystal structure contains a texture substantially identical in axial alignment to the cross-walls.
[0013] An exemplary embodiment also discloses a method for manufacturing a porous ceramic honeycomb comprising cross-walls forming channels extending axially from a first end face to a second end face. The method includes extruding a batch through a central slit of an extrusion die to form a honeycomb matrix, and extruding through a plurality of annular slits to form an outer peripheral surface layer on the honeycomb matrix, the central slit terminating at a first annular slit of the plurality of annular slits. During extrusion through the central slit and the annular slits, elongated particles in the batch are axially aligned.
[0014] An exemplary embodiment also discloses a honeycomb extrusion die, which includes a die body comprising a die face, the die face including a plurality of central slits and a surface forming region disposed around the outer periphery of the central slits, the surface forming region including a plurality of annular slits, wherein the central slits terminate at a first annular slit of the plurality of annular slits.
[0015] It should be understood that the foregoing general description and the following detailed description are merely illustrative and intended to provide further explanation of the claimed invention. Attached Figure Description
[0016] The accompanying drawings are included to further understand this disclosure. The drawings are incorporated in and form part of this specification. The drawings illustrate exemplary embodiments of this disclosure and, together with the specification, serve to explain the principles of this disclosure.
[0017] Figure 1A A perspective view of a honeycomb structure according to an exemplary embodiment of the present disclosure is shown, the honeycomb structure including a surface layer on the outer periphery of a honeycomb core. Figure 1B For the crossing of these exemplary embodiments according to this disclosure Figure 1A A cross-sectional schematic diagram of a honeycomb structure. Figure 1C For these exemplary embodiments according to this disclosure Figure 1A A top view diagram of a honeycomb structure.
[0018] Figure 2 An isometric cross-sectional view of an extrusion die with a cross-center slit extending beyond the outer peripheral slit of the surface forming the surface layer is shown.
[0019] Figure 3A For extruded green honeycomb structures with a co-extruded surface layer—for example from… Figure 2 The oriented particle microstructure of the ceramic honeycomb is extruded from the die and fired, and the cross-section of the oriented plate-like particles is equidistantly shown. Figure 3B This is a schematic diagram of the tensile stress in the extruded surface formed by aligning particles in a break region with a higher coefficient of thermal expansion (CTE) than in adjacent regions.
[0020] Figure 4 Isometric cross-sectional views of an extrusion die having a surface-forming structure region at the outer periphery of the die head, according to some exemplary embodiments of the present disclosure, are shown.
[0021] Figure 5A According to some exemplary embodiments of this disclosure, the peripheral pins and slits of the surface forming structure are shown. Figure 4 Detailed view of the mold head. Figure 5B The substrate of the peripheral pin of the variable-fine surface forming structure according to some exemplary embodiments of the present disclosure is illustrated.
[0022] Figure 6 The following is an isometric cross-sectional view of an extrusion die having a surface forming region on the outer periphery of the die head, according to some exemplary embodiments of the present disclosure. It shows plasticized batch material in the peripheral pin and slit, cover and slit, which is joined together in the knitting region and extruded as a layered surface layer.
[0023] Figure 7A This is a top view of the die exit face of a matrix slit. The matrix slit forms a structural slit by passing through the surface layer on the outer periphery of the die, from which a non-layered surface layer can be extruded. This non-layered surface layer has an misaligned area and a CTE higher than that of the adjacent surface layer area, which can cause stress concentration in the misaligned area or the adjacent surface layer area. Figure 7B This is a top view of the die exit face of a matrix slit according to some exemplary embodiments of the present disclosure, wherein the matrix slit stops at a first surface forming structure slit at the outer periphery of the die head and the layered surface extruded therefrom has a reduced misaligned area confined to the inner sheet.
[0024] Figure 8A The following is a top view of the extrusion die exit face, showing an outer peripheral pin and slit, and having a radial hole geometry matrix and a surface forming structure region on the outer periphery of the die, according to some exemplary embodiments of the present disclosure. Figure 8B yes Figure 8A Isometric cross-sectional view of the extrusion die head. Figure 8C It has a cover in the surface-forming structural region. Figure 8A Isometric cross-sectional view of the extrusion die head.
[0025] Figure 9Isometric cross-sectional views of an extrusion die having a surface-forming structure region at the outer periphery of the die head, according to some exemplary embodiments of the present disclosure, are shown.
[0026] Figure 10 Isometric cross-sectional views of an extrusion die having a surface-forming structure region at the outer periphery of the die head, according to some exemplary embodiments of the present disclosure, are shown.
[0027] Figure 11 According to some embodiments of these exemplary embodiments, a cover is provided at the outer periphery of the die head in the surface forming area. Figure 10 Isometric cross-sectional view of the extrusion die head.
[0028] Figure 12 Isometric cross-sectional views of an extrusion die having an improved surface-forming structure at the outer periphery of the die head are shown for some exemplary embodiments of the present disclosure.
[0029] Figure 13A According to some embodiments of these exemplary embodiments of the present disclosure, there is no improved surface formation structure at the outer periphery of the die head. Figure 12 A top view of the exit face of the extrusion die. Figure 13B These are some implementations based on these exemplary embodiments of the present disclosure. Figure 12 A top view of the outlet face of the improved surface-forming structure. Figure 13C These are some implementations based on these exemplary embodiments of the present disclosure. Figure 12 The bottom view at the entry surface of the improved surface-forming structure.
[0030] Figure 14A This is a schematic diagram illustrating the S-value as an ordering parameter, which is used to quantify particle alignment in green extruded articles according to some exemplary embodiments of this disclosure. Figure 14B The images show photomicrographs of each sample. The left image shows sample "A" with S = 0.8958, which has a higher degree of particle alignment than sample "B" with S = 0.7163 on the right.
[0031] Figure 15 A backscattered scanning electron micrograph (SEM) image of a cross-section of a honeycomb green body with a co-extruded non-layered surface layer on a matrix, showing three regions selected for S-value analysis. A die (e.g., with a matrix slit extending into the surface-forming structure region) is also shown. Figure 2 (As shown) used for manufacturing Figure 15 Honeycomb green products.
[0032] Figure 16Backscattered SEM images of a cross-section of another honeycomb green article having a co-extruded layered surface on a matrix, according to some exemplary embodiments of this disclosure. Figure 16 The image shows three regions selected for S-value analysis. For example... Figure 9 The die shown has radially extending slits 463 in the surface-forming structural region and is used for manufacturing. Figure 16 Honeycomb green products.
[0033] Figure 17 Backscattered SEM images of a cross-section of another honeycomb green article having a co-extruded layered surface on a matrix, according to some exemplary embodiments of this disclosure. Figure 17 The image shows three regions selected for S-value analysis. For example... Figure 4 The die shown, which has only annular extended slits in the surface structure region, was used for manufacturing. Figure 17 Honeycomb green products. Detailed Implementation
[0034] The present disclosure will now be described more fully with reference to the accompanying drawings, which illustrate exemplary embodiments of the disclosure. However, the present disclosure may be implemented in many different ways and should not be construed as limiting itself to the exemplary embodiments set forth herein. Rather, these embodiments make the disclosure thorough and enable those skilled in the art to fully demonstrate its scope. In the drawings, for clarity, the dimensions and relative dimensions of the layers and regions may be exaggerated.
[0035] It should be understood that when a described element or layer is "on" or "connected" to another element or layer, the element or layer may be directly on or directly connected to the other element or layer, or there may be intermediate elements or layers. Conversely, when a described element or layer is "directly" on or "directly connected" to another element or layer, there are no intermediate elements or layers. It should be understood that, for the purposes of this disclosure, "at least one of X, Y, and Z" can be interpreted as only X, only Y, only Z, or any combination of two or more items X, Y, and Z (e.g., XYZ, XYY, XY, YZ, ZZ, etc.).
[0036] When terms such as top, bottom, side, above, below, vertical, and horizontal are used, this disclosure is not limited to these exemplary embodiments. Rather, spatially related terms such as “top,” “bottom,” “horizontal,” “vertical,” “side,” “lower,” “below,” “below,” “above,” “upper,” etc., may be exemplified in the figures and used herein to simplify the description of the relationship between one element or feature and another element (or feature) or feature (or feature). It should be understood that spatially related terms are intended to include, in addition to the orientations shown in the figures, different orientations of the device in use or operation. For example, if the device in the figures is inverted, an element previously described as being “below” or “below” other elements or features would be oriented as being “above” other elements or features. Thus, the exemplary term “below” may encompass both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or rotated in other orientations), and the spatially related descriptions used herein may be interpreted accordingly.
[0037] "Including", "comprise" or similar terms mean including but not limited to, that is, contained within rather than exclusive.
[0038] In describing embodiments of this disclosure, the term "about" used to modify numerical values and their ranges, such as the amount, concentration, volume, process temperature, process time, yield, flow rate, pressure, viscosity, and size of components in a composition, refers to variations in quantity that may occur, for example, in typical determination and processing steps of preparing materials, compositions, complexes, concentrates, or application formulations; unintentional errors in these steps; differences in the purity of raw materials or components used to manufacture, source, or carry out the method; and similar considerations. The term "about" also includes amounts that differ from a particular initial concentration or mixture due to aging of the composition or formulation, and amounts that differ from a particular initial concentration or mixture due to mixing or processing of the composition or formulation.
[0039] In these exemplary embodiments, the articles of manufacture of this disclosure and the methods of manufacturing one or more of the articles of manufacture provided with one or more advantageous features or aspects, including, for example, those discussed below. Features or aspects listed in any claim are generally applicable to all aspects of this disclosure. Any single or multiple features or aspects described in any claim may be combined with or substituted for any other features or aspects described in any one or more other claims.
[0040] Aftertreatment of internal combustion engine exhaust gases can utilize catalysts supported on large surface area substrates and / or catalytic filters to remove soot particles. The catalyst support can be refractory, thermal shock resistant, stable under a range of pO2 conditions, non-reactive to the catalyst system, and offer low resistance to exhaust gas flow. Generally, porous ceramic flow-through honeycomb substrates and wall-flow honeycomb filters (generally referred to herein as honeycomb structures) are suitable for these applications.
[0041] Ceramic cement can be used to form the outer layer of a honeycomb structure that has been machined or "profile-defined" to the desired dimensions, or the outer layer can be co-extruded with the honeycomb structure. Co-extrusion generally refers to the flow of a batch of material through a die when forming a monolithic honeycomb component or body segment. For example, when a batch of material flows through a die to form both a matrix and a surface layer, the surface layer may be referred to as a co-extruded surface layer. As used herein, co-extrusion generally refers to the simultaneous flow of a batch of material through both the matrix region and the surface region of the die. Generally, a co-extruded surface layer can be considered integral with the matrix. As used herein, the term "honeycomb" includes both a single monolithic honeycomb component and a honeycomb segment. Individual bodies formed by fixing multiple honeycomb segments together, for example, by using ceramic cement to form a segmented monolithic component, may be referred to as segmented honeycombs.
[0042] The manufacture of porous ceramic honeycomb can be accomplished by: plasticizing a batch of ceramic powder; extruding the mixture through a honeycomb extrusion die to form a honeycomb extrusion; and cutting, drying and firing the extrusion to produce high-strength and heat-durable ceramic honeycomb and segmented honeycomb having channels extending axially from a first end face to a second end face.
[0043] Co-extruded or subsequently applied outer layers can form an outer peripheral surface extending axially from a first end face to a second end face of the ceramic honeycomb. In some embodiments, whether integral or segmented, the channels of the honeycomb defined by cross-walls (mesh) can be plugged at the inlet or outlet face to form a filter. When some channels are left unplugged at both ends, a partial filter can be formed. Whether integral or segmented, the honeycomb can be catalyzed to produce a substrate. The unplugged honeycomb is generally referred to herein as a substrate. The catalyzed substrate may have a subsequently applied catalyst or contain an extruded catalyst. Additionally, filters and partial filters can be catalyzed to provide versatility. The ceramic honeycomb thus produced can be widely used as catalyst carriers, membrane supports, wall-flow filters, partial filters, and combinations thereof for cleaning fluids, such as purifying engine exhaust or other fluid flows, such as air or gas flows or liquid or water flows.
[0044] The ceramic honeycomb composition is not specifically limited and may contain major and minor amounts of cordierite, aluminum titanate, mullite, β-spodumene, silicon carbide, zeolite, etc., and combinations thereof. As another example, the ceramic honeycomb may contain an extruded catalyst, such as extruded zeolite or other extruded catalyst materials, or a combination of various materials. Similarly, the honeycomb batch composition may contain one or more inorganic components formed by firing cordierite, aluminum titanate, mullite, β-spodumene, silicon carbide, zeolite, etc., and combinations thereof.
[0045] In some embodiments, the pore density can be between about 100 and 900 pores per square inch (cpsi). The pore wall thickness can range from about 0.025 mm to about 1.5 mm (about 1 to 20 mils). For example, the pore wall thickness can range from about 0.025 mm to about 0.30 mm (about 1 to 12 mils). For example, the honeycomb geometry 100 can be 400 cpsi with a wall thickness of about 8 mils (400 / 8) or about 6 mils (400 / 6). Other geometries include, for example, 100 / 17, 200 / 12, 200 / 19, 270 / 19, 600 / 4, 400 / 4, 400 / 3, 600 / 3, 750 / 2, 600 / 2, and 900 / 2, and other geometries. As used herein, the honeycomb 100 is intended to include a generally honeycomb-like structure, and is not strictly limited to a square structure. For example, hexagonal, octagonal, triangular, rectangular, or any other suitable hole shape or combination of hole shapes can be used. Additionally, the cross-section of the porous honeycomb 100 can be circular, but is not limited to this; for example, the cross-section can be elliptical, square, rectangular, other shapes, or combinations thereof.
[0046] Some exemplary embodiments of this disclosure relate to a honeycomb structure having a layered, integrated surface layer on a central pore structure (matrix), the layered, integrated surface layer having substantially the same physical thermal expansion properties as the matrix, i.e., for example, they have substantially the same coefficient of total thermal expansion (CTE). For example, the difference between the surface CTE and the matrix CTE can be 6 to 8 x 10⁻⁶. -7 K -1 The difference between the surface CTE and the matrix CTE can be 3 to 5 x 10⁻⁶. -7 K -1 The difference between the internal and surface CTE and the matrix CTE can be 1 to 2 x 10⁻⁶. -7 K -1Some embodiments of the exemplary embodiments of this disclosure relate to a method of forming a honeycomb structure having a layered co-extruded surface layer on a substrate, the layered co-extruded surface layer having substantially the same physical and thermal expansion properties as the substrate. Some embodiments of the exemplary embodiments of this disclosure relate to an extrusion die configured to form a honeycomb structure having a layered integrated surface layer on a substrate, the layered integrated surface layer having substantially the same physical and thermal expansion properties as the substrate.
[0047] Figure 1A A honeycomb structure 100 according to an exemplary embodiment of the present disclosure is shown, comprising a plurality of cross walls 110 forming mutually adjacent channels 112 that extend axially in the direction “Ao” between opposing end faces 114, 116. Figure 1B It shows crossing Figure 1A A schematic diagram of the cross-section of the honeycomb cell 100. Figure 1C It shows Figure 1A A top view of the honeycomb cell 100. The term "cell" is generally used herein when referring to the intersecting walls in the cross-section of the honeycomb cell, and the term "channel" is generally used when referring to the hole extending between end faces 114 and 116. The terms "hole" and "channel" are used interchangeably herein. Top face 114 refers to the area located... Figure 1A The first end face of the honeycomb 100 and the bottom face 116 refer to the second end face; however, the orientation of each end face is not limited by the orientation of the honeycomb 100. The top face 114 can be the inlet face of the honeycomb 100 and the bottom face 116 can be the outlet face, or the top face 114 can be the outlet face of the honeycomb 100 and the bottom face 116 can be the inlet face.
[0048] The central pore structure 118 may also be interchangeably referred to herein as the “matrix” or “pore matrix” of the honeycomb 100, which includes cross walls 110 defining pores 112 therebetween. The outer periphery 124 of the matrix 118 is connected to and has a co-extruded surface layer 126 disposed thereon. As will be described in more detail below, the co-extruded surface layer 126 can be considered integral with the matrix. That is, as the batch is extruded through the die, the co-extruded surface layer bonds to the matrix. After the extrudate is dried and / or fired, the surface layer 126 and the matrix 118 may become integral. According to an exemplary embodiment, the integral surface layer 126 comprises a layered structure having substantially the same thermal expansion properties as the matrix 118. For example, the difference between the CTE of the layered surface layer and the CTE of the matrix may be about 3-5 x 10⁻⁶. -7 K -1 Inside.
[0049] In some embodiments of these exemplary implementations, the thickness of the integrated surface layer 126 may be greater than the thickness of the wall 110. For example, the thickness of the integrated surface layer 126 may be greater than or equal to 0.004 inches (0.102 mm), greater than or equal to 0.010 inches (0.25 mm), or greater than or equal to 0.020 inches (0.508 mm). In some embodiments of these exemplary implementations, the coefficient of thermal expansion (CTE) of the integrated surface layer 126 may be greater than or equal to the CTE of the wall. In some embodiments of these exemplary implementations, the coefficient of thermal expansion (CTE) of the integrated surface layer 126 may be less than or equal to 15 x 10⁻⁶. -7 K -1 Furthermore, the CTE of wall 110 can be less than or equal to 15x10. -7 K -1 For example, the coefficient of thermal expansion (CTE) of the integrated surface layer 126 can be less than or equal to 10 x 10⁻⁶. -7 K -1 Furthermore, the CTE of wall 110 can be less than or equal to 10 x 10. -7 K -1 Or even the coefficient of thermal expansion (CTE) of the integrated surface layer 126 can be less than or equal to 5 x 10. -7 K -1 Furthermore, the CTE of wall 110 can be less than or equal to 5 x 10. -7 K -1 .
[0050] In some embodiments of these exemplary implementations, the isostatic compressibility of the cell 100 can be greater than 150 psi (1.03 MPa), for example greater than 200 psi (1.38 MPa), for example greater than 500 psi (3.45 MPa), greater than 1000 psi (6.9 MPa), or even greater than 2000 psi (13.8 MPa). An integrated layered surface 126 having a small mesh-affected area on the cell matrix 118 provides greater isostatic compressibility for the cell 100 than a cell without an integrated layered surface.
[0051] Methods for forming surface layers have been designed for producing integrated surface layers on cellular substrates, such as those disclosed in U.S. Patent No. 7,914,724, the entire contents of which are incorporated herein by reference as if listed in their entirety. However, methods for forming surface layers generally rely on compressing or extruding porous matrix material to form a surface layer on top of the porous matrix. This can be accomplished by using a gasket and cover located at the die exit on the outer periphery of the matrix. Additionally, pins on the die face can be cut off and angled away from the matrix edge to assist in obtaining a surface layer that does not impact the outer periphery of the matrix, which helps avoid compressing the pores at the periphery. Figure 2 The image shows a cross-sectional isometric view of an extrusion die 203, which has a die body 207, with a feed orifice at an inlet surface 209 and an extrusion slit at an outlet surface 211. A central feed orifice 213 is constructed to feed batch material to an intersecting central slit 215, and a peripheral feed orifice 217 is constructed to feed batch material to an intersecting peripheral slit 219. The central slit 215 extends beyond the surface forming structure surface 221 to the peripheral slit 219. The surface forming structure surface 221 may form a cavity having a cover (not shown) spaced from the surface forming structure surface 221 by a distance equal to the thickness of the co-extruded surface layer at the honeycomb matrix.
[0052] In this type of use of mold heads—for example Figure 2 The die head shown, in which the central slit 215 extends beyond the surface of the surface-forming structure 221 to the outer peripheral slit 219—in the method of forming the surface layer, the honeycomb surface layer is formed by a different process than the co-extruded honeycomb matrix, thereby resulting in a surface layer with physical properties different from those of the matrix. For example, it has been found that the coefficient of thermal expansion (CTE) changes on the surface layer and is generally higher than the CTE measured in the matrix within a dried and fired ceramic honeycomb.
[0053] While not wishing to be confined to theory, the variability of CTE is a consequence of the disruption of particle orientation involving the extruded mesh. (Reference) Figure 2 , 3A Along with 3B, plate-shaped talc and clay particles 331 are commonly used to produce ceramic (e.g., cordierite) honeycomb 333. As these plate-shaped particles 331 pass through the slits 215, 219 of the die 203 during the extrusion process, they become oriented and remain oriented in the extruded green portion. After firing, the high orientation produces a cordierite body with cordierite crystals, which are preferably oriented (aligned) so that their low expansion c-axis 335 is in the plane of the wall 337. This orientation is referred to herein as "axially aligned construction". If the crystals are randomly oriented relative to the plane of the mesh, this results in a lower coefficient of thermal expansion than expected. Since these types of surface-forming methods rely on the compression of the extruded mesh through the intersecting peripheral slits 219 to produce the surface 339, the particle microstructure produced by the compression action of the mesh is significantly less oriented or more randomly oriented (non-aligned) 341 than the adjacent matrix walls 337.
[0054] The contrast between the oriented microstructure of particles in the matrix wall 337 and the misaligned microstructure of particles in the surface layer 339 is most pronounced at points in the surface layer where there is no matrix wall 337 parallel to the surface layer 339. This occurs everywhere except at 90°. Furthermore, at the 90° point on the outer periphery, the surface layer 339 has already been formed by material extruded through slit 219, which is parallel and perpendicular to the surface layer 339. Therefore, the portion of the mesh that was once perpendicular to the surface orientation needed to be compressed to become part of the surface layer 339. This results in particle misalignment, even in the region of the surface layer 343 at 90°. This surface layer formation results in stress 345 at the interface due to thermal expansion mismatch at the surface-matrix interface, generated during use under heating and cooling. The region of the surface layer 339 of the misaligned particle microstructure 343 is referred to herein as the "network influence zone" and may have a higher CTE than the matrix wall 337 and a higher CTE than the adjacent surface layer 339, resulting in tensile stress and cracked zones 347. This situation exists in most pore geometries, including square, circular, hexagonal, rectangular, etc.
[0055] Radial hole ceramic honeycomb design is disclosed in U.S. Patent No. 7,575,793, the entire contents of which are incorporated herein by reference as if listed in their entirety. A characteristic of the radial hole ceramic honeycomb design is that the pore structure comprises radial walls radiating from a central location and a series of concentric ring walls intersecting the radial walls. The portion of the die used to produce the radial hole ceramic honeycomb structure that forms the surface layer contains mesh walls that are always parallel to the surface layer. This helps to minimize the mismatch between the physical properties of the matrix and the surface layer. However, conventional hardware for forming the surface layer still relies on the compression of the concentric rings and the vertical radial mesh. Surprisingly, the inventors have discovered a method for producing a surface layer, as disclosed herein, in which the material primarily or entirely contained within the surface layer is generated in the slits forming the concentric rings. By removing the radial slits in the region forming the surface layer, the particles present in the green body and the microparticle microstructure in the fired ceramic article are oriented in substantially the same manner and have substantially the same orientation as the internal mesh. This new discovery, according to the exemplary embodiments disclosed herein, results in the integrated surface layer having substantially the same physical thermal expansion properties as the matrix.
[0056] According to an exemplary embodiment of the present disclosure, a honeycomb structure having a layered integrated surface layer on a central hole structure, the layered integrated surface layer having substantially the same physical and thermal expansion properties as the matrix; a method for forming a honeycomb structure having a layered integrated surface layer; and an extrusion die constructed for forming a honeycomb structure having a layered integrated surface layer, all three of which reduce the mesh influence area and overcome stress and cracking caused by the mismatch of the physical and thermal expansion properties of the surface layer and the matrix.
[0057] Figure 4 Isometric cross-sectional views of an extrusion die having a surface-forming structure region at the outer periphery of the die head are shown for some exemplary embodiments of this disclosure. The extrusion die 403 has a die head body 407, with a feed orifice at an inlet surface 409 and an extrusion slit at an outlet surface (die face) 411. A central feed orifice 413 is configured to feed batch material axially from the batch cavity in direction “Ao” to the intersecting central slit 415, and a peripheral feed orifice 417 is configured to feed batch material from the batch cavity into the slit in the surface-forming structure region 419 at the outer periphery of the matrix. Figure 5A According to these exemplary embodiments of the present disclosure, peripheral pins and slits of the surface forming structure are shown. Figure 4 Detailed view of the mold head. Figure 5B An example of a substrate for an annular ring with a variablely thin surface forming structure according to some exemplary embodiments of the present disclosure is shown. The surface forming structure region 419 may form a cavity with a cover.
[0058] refer to Figure 4 , 5A In conjunction with 5B, the intersecting central slit 415 defines the central matrix pin 421 and does not extend beyond the first annular ring 423 in the surface formation region 419. The matrix pin 421 at the outer periphery of the matrix is spaced apart from the first annular ring 423 by the first annular slit 425. The second annular ring 427 is spaced apart from the first annular ring 423 by the second annular slit 429. Optionally, one or more additional annular rings may be similarly provided outside the first and second annular rings 423, 427 to form one or more additional slits.
[0059] The outer peripheral feed hole 417 can extend into the annular rings 423 and 427 to form a reservoir 434 to feed batch material into the radial slits 425 and 429, such as Figure 4 , 5A As illustrated in 5B. Alternatively, according to some embodiments of these exemplary embodiments, radial slits 425, 429 may include a tapered base 436 to feed batch material into radial slits 425, 429, such as Figure 5B exemplified. <0}
[0060] The first and second annular rings 423 and 427 may each have outlet surfaces 431 and 433, respectively, which are angled away from the center of the die body 407, and a cover (not shown) may be placed on top of the die 403 in the surface forming structure region 419 to create channels for the extruded surface to contact and bond with the matrix extrudate. In this type of die use—for example… Figure 4 , 5AThe die head shown in 5B, wherein the central slit 415 does not extend beyond the first annular ring 423 in the surface forming structure region 419 on the outer periphery—in the method of forming the surface layer, the honeycomb surface layer is formed by a process similar to that of the honeycomb matrix during co-extrusion, so that the physical thermal expansion properties of the resulting surface layer are substantially the same as those of the matrix.
[0061] According to some embodiments of these exemplary embodiments, the central slit 415 may have a thickness greater than or equal to 0.001 inches (0.0254 mm) and less than or equal to 0.014 inches (0.356 mm), and the annular slits 425, 429 may have a thickness greater than or equal to 0.001 inches (0.0254 mm) and less than or equal to 0.014 inches (0.356 mm). According to some embodiments of these exemplary embodiments, the exit surfaces 431, 433 of the first and second annular rings 423, 427 may be at an angle away from the center of the die body 407, said angle being greater than or equal to 0 degrees and less than or equal to 60 degrees from the parallel to the die exit surface. According to some embodiments of these exemplary embodiments, there is no specific limitation on the number of annular slits, and they may include 2 to 7 slits. For example, the number of annular slits can include two, three, four, or five annular slits. Since the area of influence of the mesh is greatly limited to the first annular slit adjacent to the matrix slit, adding annular slits further restricts the area of influence of the mesh to a narrower portion of the surface layer in the thickness direction.
[0062] Figure 6 This is an isometric cross-sectional view of an extrusion die having a surface forming region on the outer periphery of the die head, according to some exemplary embodiments of the present disclosure. It shows plasticized batch material in the peripheral pins and slits, the cover and slits, which is bonded together in the joining region and extruded as a layered surface layer. Figure 6 In the structure, slits 415 are provided between each matrix pin 421, each matrix pin 421 including an outermost pin 435, which is spaced apart from a first annular ring 423 by the first annular slits 425. The annular rings 423, 427 can be considered as pins, but not pins in the conventional sense, but rather rings. As used herein, a ring refers to a shape that surrounds the matrix and is not intended to be limited to any particular shape, but it can include circular, elliptical, asymmetrical shapes, combinations of straight and curved segments, and other shapes of the honeycomb cross-section. Figure 6 A schematic diagram illustrates the flow pattern of batch material supplied to the surface through slits. It also shows the batch material flowing through the slits and being supplied to the matrix, depicted as dashed lines. The batches are shown in different shades (A, B, C, and D) to distinguish the different flow paths of the batches flowing through the surface to form structural regions and within the matrix.
[0063] Shown Figure 6 The surface layer 451 is referred to herein as layered because, as described above, the plate-like particles in the batch, which become oriented during the extrusion process through the slits 413 and 425 of the die 403, become misaligned in the network-affected zone. However, the plate-like particles in the batch, which become oriented during the extrusion process through the outer annular slits 429 and 439 of the die 403, hardly become misaligned and remain oriented in the extruded green portion 449. The network-affected zone hardly extends from the outer annular slits 429, 439 forming the outer layer of the surface layer 451 into the batch. The plurality of annular slits 425, 429, 439 that orient the batch particles provide the layered surface layer 451. Upon firing, the high orientation produces a ceramic body with ceramic crystals, which are preferably oriented (aligned) in the outer surface layer with their low expansion axes in the plane of the surface layer, because the low expansion axes of the ceramic crystals in the network wall are oriented with their low expansion axes in the plane of the wall. However, the fired ceramic surface is generally no longer layered; the ceramic crystals are preferably oriented (aligned) to limit the reduced network influence area to the surface thickness extruded through the first annular slit in the outer surface. This fired ceramic surface is referred to herein as a uniform surface.
[0064] according to Figure 6 In the exemplary embodiment shown, the rings 423, 427 forming the surface layer are recessed below the exit surfaces of the matrix pins 421, 435, and the exit surfaces 431, 433 are angled away from the surface and center of the die head 403. A cover 441 is depicted in the surface layer forming structure region on the gasket 443 to regulate the flow of the batch material in the surface layer forming structure region. The cover 441 and the surface layer forming slits 425, 429, 439 are configured to allow the batch material to form a layered structure in the surface layer forming gap 457, as shown in the central portion of the figure. The edges of the covers 445, 447 adjacent to the outermost pin 435 taper towards the pin 435 to facilitate compression and bonding of the layers of batch material A, B, C, forming the surface layer 451 in the surface layer forming gap 457. A portion of the cover edge 447 facing the exit surface may have a small angle to bond the layered surface structure to the matrix 453 in the bonding region 437.
[0065] The extruded green honeycomb wall 453 of the matrix is shown in dashed lines and contacts the extruded layered surface layer between the outermost matrix pins 435 and at the slits 415 between the outermost matrix pins 435 and the first annular ring 423. Therefore, any orientation interruption in the batch particles can be limited to a small area of surface layer thickness. For example, when two surface layers are used to form the slits, the mesh-affected area can be limited to no more than about half the surface layer thickness, and when three surface layers are used to form the slits, the mesh-affected area can be limited to no more than about one-third the surface layer thickness. For example, when four surface layers are used to form the slits, the mesh-affected area can be limited to no more than about one-quarter the surface layer thickness; when five surface layers are used to form the slits, the mesh-affected area can be limited to no more than one-fifth the surface layer thickness; and when six surface layers are used to form the slits, the mesh-affected area can be limited to no more than one-sixth the surface layer thickness.
[0066] When using two or more annular surface layers to form slits, the integrated layered surface layer can be thicker than the matrix mesh to improve the strength of the honeycomb. The thick layered surface layer can still have substantially the same physical and thermal expansion properties as the thin mesh, thus avoiding radial cracks and fissures that would otherwise form during processing (e.g., firing) and during use (e.g., in automotive exhaust treatment).
[0067] Figure 7A This is a top view of the die exit face of the matrix slit 215. The matrix slit 215 passes through the surface layer to form a structural slit 219 on the outer periphery 223 of the die, from which a non-layered surface layer 339 can be extruded. The non-layered surface layer 339 has an misaligned region 343 and a CTE higher than the adjacent surface region, which can cause stress concentration in the misaligned region 343 or the adjacent surface region. Figure 7B The image is a top view of the die exit face 411 of a matrix slit 415 according to some exemplary embodiments of the present disclosure. The matrix slit stops at a first surface forming structure slit 425 at the outer periphery 459 of the die head, and the layered surface layer 126 extruded therefrom has a reduced misaligned area substantially confined to the inner sheet.
[0068] Figure 8A For some exemplary embodiments according to this disclosure, a top view of the extrusion die 800 outlet face 411 is shown, with peripheral pins 423, 427 and slits 425, 429, 439, and radial hole geometry matrix and surface forming structure region having slits 415 and pins 421 on the outer periphery of the die. Figure 8B yes Figure 8A Isometric cross-sectional view of the 800mm extrusion die. Figure 8C It has a cover 441 in the surface-forming structural region. Figure 8AIsometric cross-sectional view of extrusion die 800. The peripheral pins 423, 427 of extrusion die 800 do not have radial slits. Extrusion die 800 has a die body 407 with an open cavity feed port at the entry surface 409. A central open cavity 442 is constructed to feed batch material axially from the batch cavity to the intersecting central slit 415, and a peripheral open cavity 444 is constructed to feed batch material from the batch cavity to slits in the surface-forming structure region 419 at the outer periphery of the matrix.
[0069] Figure 9 For some exemplary embodiments according to this disclosure, isometric cross-sectional views of an extrusion die 900 having a surface-forming structure region at the outer periphery of the die head are shown. The surface-forming pins 467, 469 have radial slits 463 to enhance the bonding between the surface layer sheets. To maintain good orientation of the particles in the layered surface, the occurrence rate of the radial slits 463 is less than the occurrence rate of the matrix slits at the first surface-forming slit 425. As used herein, the slit occurrence rate refers to the number of slits per unit length at the first annular slit 425. For example, if the matrix slit 415 intersects the first annular slit 425, there can be ten matrix slits 415 within a given distance, and four radial slits 463 within the same distance. Due to the geometry of the matrix, the matrix slits 415 can be unevenly distributed within a given distance. The radial slits 463 are located at... Figure 9 The examples illustrate a uniform distribution, but are not limited to this. For instance, for a square pin 421 substrate, the surface-forming pins 467, 469 may have fewer radial slits 463 when oriented at 45° than when oriented at 90°, or for a hexagonal pin 421 substrate, the surface-forming pins 467, 469 may have fewer radial slits 463 when oriented at 30° than when oriented at 60°. The surface-forming pins 467, 469 are also referred to herein as loops, and the radial slits 463 may have various depths 465 to enhance the bonding between the surface sheets.
[0070] Figure 10 Isometric cross-sectional views of an extrusion die 903 having a surface-forming structure region at the outer periphery of the die head, with peripheral pins 467, 469 and slits 425, 429, are shown for some exemplary embodiments of this disclosure. The extrusion die 903 is similar to the extrusion die 900, but the extrusion die 903 has a hexagonal matrix pin 421. Although in Figure 10 Not shown, but the outermost matrix pin 435 may also have a side portion facing the first annular ring 425, which is similar to Figure 2 The surface forming structure 221 of the layer is at an angle away from the center of the die head 903, and the outermost matrix pin 435 may also have outlet surfaces 431, 433 to allow the layered surface to bond with the matrix.
[0071] Figure 11 According to some embodiments of these exemplary embodiments, a cover 441 is provided at the outer periphery of the die head in the surface forming area. Figure 10 Isometric cross-sectional view of the extrusion die 903. The cover 441 is shown in a transparent form only to illustrate the structure of the die 903 located below in the surface-forming structure region 419.
[0072] Figure 12 Isometric cross-sectional views of an extrusion die 905 with an improved surface forming structure 911 at the outer periphery of the die head, comprising peripheral slits 913, 915, 917, 919, and 921, are shown for some exemplary embodiments of the present disclosure. The improved surface forming structure 911 has annular rings 923, 925, 927, and 929 defining the annular slits 913, 915, 917, 919, and 921 for use similar to those described in the foregoing references. Figure 4 The layered surface layer is formed in the embodiment described in 5. In addition, the improved surface layer forming structure 911 has feed holes 931 and 933, which are configured to supply batch material to the annular slits 913, 915, 917, 919, and 921.
[0073] The improved surface forming structure 911 may have a first surface 935 for contacting a corresponding surface 937 on the die body 939. The improved surface forming structure 911 may also have a second surface 941 for contacting a corresponding surface 943 on the die body 939. In this way, the improved surface forming structure 911 can be tightly fitted to the die body 939 while maintaining fluid communication between the feed port 417 and the feed ports 931, 933. Fixtures, bolts, etc. (not shown) may be used to secure the improved surface forming structure 911 to the die body 939 to prevent batch leakage. The die body 939 may have a chamber 945 in surface 937 to receive batch material from the die feed port 417 and supply the batch material to the improved surface forming structure feed ports 931, 933.
[0074] Figure 13A According to some embodiments of these exemplary embodiments of the present disclosure, the improved surface formation structure 911 is not present at the outer periphery of the die head. Figure 12 A top view of the exit face 411 of the extrusion die 905. Figure 13B These are some implementations based on these exemplary embodiments of the present disclosure. Figure 12 A top view of the exit face of the improved surface forming structure 911. An opening 947 defined by a second surface 941 is constructed to assemble the matrix around the die head 905. Figure 13C These are some implementations based on these exemplary embodiments of the present disclosure. Figure 12Bottom view of the entry surface of the improved surface forming structure 911.
[0075] Example
[0076] Figure 14A This is a schematic diagram illustrating the S-value as an ordering parameter, used to quantify particle alignment in green extruded articles according to some exemplary embodiments of this disclosure. To quantify the degree of order present in a material (green extruded substrate material), the ordering parameter (S) is referred to herein as follows:
[0077] S = (1 / 2) < 3 cos 2 -1> Equation (1)
[0078] in (Sita) is the angle between the defined orientation and the major axis of each molecule. Parentheses indicate the average value of all molecules in the sample. In isotropic liquids, the average value of the cosine term is zero, therefore the order parameter is equal to zero, indicating that the molecules are completely randomly oriented. For perfect crystals (where all molecules are aligned in the same direction), the order parameter is evaluated to be 1. Figure 14B The images show photomicrographs of each sample. The left image shows the photomicrograph of sample "A1" with S = 0.8958, which has a higher degree of particle alignment than sample "A2" with S = 0.7163 on the right.
[0079] Figure 15 A backscattered scanning electron micrograph (SEM) image of a cross-section of a honeycomb green body with a co-extruded non-layered surface layer on a matrix, showing three regions selected for S-value analysis. A die (e.g., with a matrix slit extending into the surface-forming structure region) is also shown. Figure 2 (As shown) used for manufacturing Figure 15 Honeycomb green products.
[0080] Figure 16 Backscattered SEM images of a cross-section of another honeycomb green article having a co-extruded layered surface on a matrix, according to some exemplary embodiments of this disclosure. Figure 16 The image shows three regions selected for S-value analysis. For example... Figure 9 The die shown has radially extending slits in the surface structure region and is used for manufacturing. Figure 16 Honeycomb green products.
[0081] Figure 17 Backscattered SEM images of a cross-section of another honeycomb green article having a co-extruded layered surface on a matrix, according to some exemplary embodiments of this disclosure. Figure 17 The image shows three regions selected for S-value analysis. For example... Figure 4 The die shown, which has only annular extended slits in the surface structure region, was used for manufacturing. Figure 17 Honeycomb green products.
[0082] Polished sections were prepared from parts dried at 200 °C for 4 hours to facilitate further drying and remove some oiliness to aid the epoxy impregnation process. Samples were cut and polished to produce individual specimens from each sample. Specimens were polished on the cross-section of the open face of the part. Figure 15 The polished cross section of the comparative sample (CS) shown is as follows: Figure 16 (ES1) and Figure 17 The polished cross section of the exemplary sample (ES2) shown is prepared by an evaporation of a conductive carbon coating onto the sample to reduce charging. The sample was then analyzed using a Zeiss® 1550VP at 20 kV and 300x magnification.
[0083] A large field of view was acquired using the large-area mapping automated image acquisition software package in Oxford Instruments Aztec EDS microanalysis® software to observe particle alignment in the surface, thus imaging the polished specimens at 300x magnification. An image montage of the joints of each specimen is shown.
[0084] Media Cybernetics Image Pro Premier® image analysis software was used to quantify the S-value parameter. The montage image was segmented to create an image mask that separated larger talc, silica, and alumina particles from smaller clay particles. The masked image was then used to segment particles larger than 25... m 2 The angle (in degrees) of the major axis of each particle from reference 0 Quantification is performed starting from the horizontal image axis. The angle (in degrees) of each particle is converted to radians, and the S-value parameter defined in equation (1) is calculated. The average S-value parameter is calculated using the descriptive statistics program in Microsoft Excel®.
[0085] The S-values for the comparative sample (CS) are shown in Table 1 below, the S-values for exemplary sample 1 (ES1) are shown in Table 2 below, and the S-values for exemplary sample 2 (ES2) are shown in Table 3 below. The lower the S-value, the more disordered the particle alignment.
[0086] Table 1 <0} Table 2 <0} Table 3 <0} Some differences in particle alignment were found between the samples. The layered surface provided improved orientation in the region away from the surface towards the mesh interface. More aligned particles were also found along the long axis or extrusion direction of the part, but less aligned in the cross-section of the part. The large black cracks in the micrographs were caused by the low-pressure experimental die used to manufacture the examples. However, Figure 15 The shapes of these cracks in CS regions 1 and 2 indicate large network-like influence zones. Conversely, for ES1 and ES2... Figure 16 and 17 The diagram shows fewer cracks, and the cracks are parallel to the surface layer, which, according to the description of the exemplary embodiments of this disclosure listed herein, indicates a significantly smaller area affected by the network.
[0087] According to some embodiments of these exemplary implementations, the order parameter S, which is greater than 50% of the surface wall thickness, can be greater than or equal to 0.4, for example, greater than or equal to 0.45, or even greater than or equal to 0.5. Furthermore, the order parameter S, which is greater than 60% of the surface wall thickness, can be greater than or equal to 0.4, for example, greater than or equal to 0.45, or even greater than or equal to 0.5. Even further, the order parameter S, which is greater than 70% of the surface wall thickness, can be greater than or equal to 0.4, for example, greater than or equal to 0.45, or even greater than or equal to 0.5.
[0088] According to exemplary embodiments of this disclosure, a surface layer produced by a die having an annular ring defining annular slits can reduce or eliminate stress previously caused by a mismatch in the physical thermal expansion properties between the matrix and the surface layer during heating and cooling when using the ceramic honeycomb. Failure of ceramic honeycombs in furnace thermal shock tests typically occurs at the surface layer; therefore, an integrated layered surface layer disposed on the matrix as disclosed herein, with particles oriented as if within the matrix, can improve the failure temperature in furnace thermal shock tests. Improved matching of the coefficients of thermal expansion between the surface layer and the matrix improves the thermal shock resistance of the honeycomb. Furthermore, the method disclosed herein, by disposing an integrated layered surface layer on the matrix having the same particle orientation as the matrix, can improve surface layer thickness uniformity and improve the isostatic compressive strength of the honeycomb.
[0089] It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed exemplary embodiments without departing from the spirit or scope of this disclosure. Therefore, the appended claims are intended to cover such modifications and variations as long as they fall within the scope of the appended claims and their equivalents.
Claims
1. A honeycomb extrusion die, comprising: The die head body includes: The die head surface includes a plurality of intersecting central slits and a surface forming structure region disposed around the outer periphery of the central slits. The intersecting central slits define a plurality of matrix pins extending axially to an exit face. The surface forming structure region includes a plurality of annular slits, which define annular rings extending axially to the exit face. The central slits terminate at a first annular slit of the plurality of annular slits and extend beyond a first annular ring of the plurality of annular rings in the surface forming region. A central feed hole connected to the central slit; The outer peripheral feed port communicates with the annular slit; and The matrix pin extends further axially than the annular rings and includes an outlet surface that is substantially parallel to the die face, and the plurality of annular rings include radially extending slits and outlet surfaces that slope away from the matrix pin.
2. The honeycomb extrusion die as described in claim 1, wherein, At the first annular slit, the occurrence rate of radially extending slits is less than that of the central slit.
3. The honeycomb extrusion die as described in claim 1, wherein, The central slit contains a thickness greater than or equal to 0.001 inches (0.0254 mm) and less than or equal to 0.014 inches (0.356 mm).
4. The honeycomb extrusion die as described in claim 1, wherein, Each annular slit contains a thickness greater than or equal to 0.001 inches (0.0254 mm) and less than or equal to 0.014 inches (0.356 mm).
5. The honeycomb extrusion die as described in claim 1, wherein, The plurality of annular slits includes at least two annular slits and less than five annular slits.
6. The honeycomb extrusion die as described in claim 1, wherein, The exit surface of the annular ring is inclined at an angle away from the matrix pin, said angle being greater than or equal to 0 degrees from the die head exit surface and less than or equal to 60 degrees from the die head exit surface.
7. The honeycomb extrusion die as described in claim 1, wherein, The central slit defines the radial pin.
8. The honeycomb extrusion die as described in claim 1, wherein, The substrate pin is hexagonal.
9. The honeycomb extrusion die as described in claim 1, wherein, The plurality of matrix pins includes the outermost matrix pin, and the side of the outermost matrix pin facing the first annular ring is inclined away from the center of the die head.
10. A method for manufacturing a ceramic honeycomb body using a honeycomb extrusion die as claimed in claim 1, the ceramic honeycomb body comprising intersecting walls forming channels extending axially from a first end face to a second end face, the method comprising: The batch material is extruded through the central slit of the extrusion die to form a honeycomb matrix, and then extruded through multiple annular slits to form an outer peripheral surface layer on the honeycomb matrix. During extrusion through the central slit and annular slit, the elongated particles in the batch are axially aligned.
11. A green honeycomb body obtained by the method of claim 10.
Citation Information
Patent Citations
Radial cell ceramic honeycomb structure
US7575793B2