CN101495422B - Low-microcracked, porous ceramic honeycombs and methods of manufacturing same - Google Patents

Abstract

The invention provides substantially non-microcracked, porous, cordierite ceramic honeycomb bodies. Although exhibiting moderately high thermal expansion (CTE) between 7*10<-7> to 16*10<-7>/ DEG C. (25-800 DEG C.), the honeycomb bodies exhibit relatively high thermal shock parameter (TSP), such as TSR>=525 DEG C. by virtue of a high MOR/E ratio, and/or low Eratio=ERT/E1000 DEG C. and well interconnected porosity, as witnessed by a relatively high pore connectivity factor (PCF). The invention also provides a method of manufacturing the honeycomb ceramic structure.

Description

Low-microcracked porous ceramic honeycombs and manufacture method thereof

Related invention

The application requires the title of submitting on August 29th, 2006 to be No. 60/840th, 806, the U.S. Provisional Application sequence of " non-microcracked thermotolerance porous ceramics "; The title that on June 30th, 2006 submitted to is the U.S. Provisional Application sequence the 60/817th of " the high porosity filters device that is used for 4-passage off gas treatment ", No. 722 and be right of priority and the rights and interests of No. 11/544th, 271, the U.S. Patent application sequence of " for the high porosity filters device of 4-passage off gas treatment " in the title that on August 6th, 2006 submitted to.

Invention field

The present invention relates to porous honeycomb body pottery and manufacture method thereof, more specifically, relate to the porous cordierite honeycomb pottery for catalytic converter and particulate filter (as being used for the aftertreatment of engine exhaust).

Background of invention

The porous ceramic honeycombs structure is widely used as substrate for catalytic converters and/or diesel particulate filter.The cordierite ceramic honeycomb that is used for the earliest these application consists of the cordierite substrates of reaction sintering, and described cordierite substrates is by talcum, aluminum oxide and kaolinic mixture are extruded preparation, as US3, described in 885,977.Find that these ceramic honeycomb bodies have the chemical durability that is fit to these application, inertia, infusibility and resistance to sudden heating, and generally can be with the reasonable cost manufacturing., for purpose described herein, unless otherwise indicated, otherwise only use term " trichroite " expression rhombic system trichroite (orthorhombic cordierite) (rhombic system Mg ₂Al ₄Si ₅O ₁₈With its solid solution), indialite (hexagonal system Mg ₂Al ₄Si ₅O ₁₈With its solid solution), and their mixture.

The high resistance to sudden heating of the cordierite ceramic of reaction sintering is directly proportional to the ratio of elasticity (Young) modulus (E) to the rupture modulus (MOR) of pottery, and with this ceramic thermal expansivity (CTE), be inversely proportional to, this is owing to forming specific microstructure during curing, specific microstructure depends on suitable selection and the shaping of employing and the method for curing of raw material.Preferably, ceramic interior trichroite crystallization meeting preferably, with its orientation of negative expansion z-axle near the wall planar alignment, therefore reduces the CTE of honeycomb in axial and radial direction.

In addition, large (〉 50 μ m) cooling period that is formed on of fan-shaped " domain structure (domain) " of radiation rhombus cordierite crystal produces internal stress, causes producing tiny crack in whole cordierite body.These tiny cracks during follow-up reheating more closed held cordierite crystal just-the x-axle of CTE and the expansion to a certain degree of y-axle, therefore further reduce total CTE of cordierite body.People think always, and the extremely low CTE that preferred orientation and high level tiny crack produce is most important for the heat durability of base material.

Technology to the substrate for catalytic converters research and development generally also is suitable for ceramic diesel engine particulate filter (DPF).Monolithic DPF can be prepared by porous ceramic honeycombs in the following manner: alternately stop up the end in adjacent duct, for example,, as " halma board " pattern, form " wall stream " strainer with import duct and outlet duct.This structure forces the waste gas that enters to pass through from the porous honeycomb body wall, passes wall construction, therefore plays the particulate of collection waste gas such as the effect of soot on internal wall.The convertor base material has relatively low porosity (25-35%) and is fit to apply tiny aperture (mean pore sizes is about 4 microns) with attached catalyst wash coat (washcoat), with respect to the convertor base material, the DPF of prior art requires higher porosity and thicker aperture, the back pressure while to reduce, passing through wall.This can be by using thicker talcum and silica material and adding thick pore former (as Graphite Powder 99) and realize.Pore former burnouts and leaves wall during curing, therefore help to reach high porosity.

The recent tendency of the exhaust after-treatment aspect of gasoline and diesel motor has proposed more requirement to convertor and DPF.To convertor, turned to high density holes more and thinner wall (as, 900/2), this turning to will face many challenges meeting aspect intensity and erosion resistance requirement.Along with to being used for the concern with the more high porosity convertor of the low thermal mass that meets emission standard of rapid-ignition more, for reducing back pressure, require low hole density and thin-walled (as, 300/4 or 600/3 configuration (cpsi/t _Wall)) more recent application similarly challenge is proposed.

Equally, in the past to DPF, the porosity of 45%-50% enough is used for various application, may need even higher porosity and thicker aperture towards the turning to of DPF of catalysis, so that catalyzer is contained in porous wall.Considering the aperture of high porosity to 60%-70% and 20-25 micron.

All these trend have all improved the requirement to honeycomb strength, still, to guaranteeing the requirement that cordierite ceramic honeycomb has a low CTE, have still determined to have tiny crack.Tiny crack has limited the maximum strength that ceramic substrate itself can reach.Therefore, the variation by the honeycomb bore geometry (as the filleting to the wall point of crossing (filleting) or at the periphery of the honeycomb near top layer, providing thicker wall), improve the intensity of the honeycomb of thin-walled design.

Use comprises the molecule that two problems of the convertor of the crack trichroite that splits and DPF are catalyst wash coat and penetrates in the tiny crack that forms in trichroite matrix.Being present in the closure that particle in tiny crack may disturb tiny crack between heating period, is mainly as the pin plug, crackle to be opened wide.This may cause CTE to increase, and also increases Young's modulus, and these two factors all can reduce resistance to sudden heating.This especially becomes problem for DPF, and to DPF, catalyst wash coat is arranged in the porous wall of strainer usually.

Finally, the degree of preferred orientation not simultaneously, also has problems to low CTE trichroite desired highly preferred " plane " orientation between top layer and pore matrix.The reason that this phenomenon occurs may be the different degree of alignment of the sheet-shaped material that different shearing and mobile difference cause in top layer and matrix when by die head, extruding.Because the difference of trichroite orientation, top layer and matrix can have different CTE.As a result, cooling period after curing, top layer and matrix may be shunk with different speed, produce tension stress in top layer, may cause forming crackle in top layer.These crackles can reduce intensity and resistance to sudden heating.

Based on the above discussion, clearly, although crack split with preferred crystallite orientation be all in the past realize in the cordierite ceramic of reaction sintering low CTE and high resistance to sudden heating necessary,, these microstructure features have also produced and have limited these materials and be used for the problem of some application.For example, may cause strength degradation while infiltrating catalyzer or particulate in tiny crack, and may promote CTE to increase.In addition, variable trichroite domain structure is aimed at and may produce unrelieved stress in cordierite honeycomb bodies.

Summary of the invention

This class problem that improvement of the present invention or minimizing are relevant to prior art, the i.e. highly crack material that splits.Therefore, the present invention relates to a kind of substantially without the crack porous cordierite ceramic honeycomb that splits.According to the embodiment of the present invention, cordierite ceramic honeycomb has high resistance to sudden heating and low thermal expansivity.In addition, this honeycomb has high strain tolerance (strain tolerance) because of MOR/E ratio relatively high under room temperature.More specifically, according to embodiment, the thermal shock parameter of honeycomb of the present invention (TSP) value is at least 400 ℃, and simultaneously CTE is lower, is (25-800 ℃ time)≤15x10 ^-7/ ℃, wherein, TSP is defined by following equation:

TSP=MOR _{Room temperature}/ [E _{Room temperature}] [CTE _H]

Wherein, MOR _{Room temperature}The rupture modulus of cordierite ceramic when crooked corresponding to room temperature 4-point, CTE _HCorresponding to the mean value of the high temperature thermal expansivity of material, this coefficient is coefficient when the temperature range heating of 500-900 ℃ or the coefficient of calculating.Honeycomb wall has arbitrarily or preferred cordierite crystal orientation, but finds according to another aspect of the present invention to compare with any crystalline orientation, and preferred orientation (the z-axle of trichroite is parallel to wall surface) provides relatively low CTE.

In addition, another aspect of broad sense of the present invention, provide the porous ceramic honeycombs structure, and this honeycomb comprises main cordierite ceramic phase, and this ceramic phase has the room temperature Young's modulus (E of 25 ℃ _{Room temperature}) and the high-temperature elastic modulus (E of 1000 ℃ _H), and

E _{Ratio 1000}≤ 1.05, E wherein _{Ratio 1000}=E _H/ E _{Room temperature}, and

TSP 〉=525 ℃, wherein, thermal shock parameter (TSP) is defined as follows:

TSP=MOR _{Room temperature}/ [E _{Room temperature}] [CTE _H]

(MOR _{Room temperature}) be room temperature breaking tenacity modulus, (CTE _H) be the high temperature thermal expansivity between 500-900 ℃.MOR, E and CTE measure on the hole sample that is parallel to orifice throat length (also referred to as axially).E _HMeasuring between heating period from room temperature.In addition, the present invention shows, E _{Ratio 1000}≤ 1.01, E _{Ratio 1000}≤ 1.00, E _{Ratio 1000}≤ 0.98, E _{Ratio 1000}≤ 0.95, perhaps E even _{Ratio 1000}≤ 0.93.In addition, honeycomb body structure of the present invention can show relatively low CTE, as CTE (25-800 ℃)≤18x10 ^-7/ ℃, CTE (25-800 ℃)≤16x10 ^-7/ ℃, CTE (25-800 ° of C)≤15x10 ^-7/ ℃, CTE (25-800 ℃)≤14x10 ^-7/ ℃, CTE (25-800 ℃)≤12x10 ^-7/ ℃, CTE (25-800 ℃)≤10x10 ^-7/ ℃, perhaps CTE (25-800 ℃)≤9x10 even ^-7/ ℃.Except E as above _{Ratio 1000}≤ 1.05 and TSP 〉=525 ℃ outside, the hole microstructure of the porosity that embodiments of the present invention can also be by further comprising relatively narrow pore size distribution characterizes.Particularly, embodiment also comprises narrow pore size distribution, wherein, and the porosity d-factor (d _f) by equation d _f=(d ₅₀-d ₁₀)/d ₅₀Definition, this d-factor can be d _f≤ 0.48, d _f≤ 0.40, d _f≤ 0.37, d _f≤ 0.35, d _f≤ 0.30, d _f≤ 0.28, perhaps d even _f≤ 0.25.And the narrow pore size distribution of the honeycomb of humble cracking can also be defined by the hole microstructure, wherein, and total aperture width (d _b), be defined as d _b=(d ₉₀-d ₁₀)/d ₅₀, this d _bMay be d _b≤ 1.65, d _b≤ 1.23, d _b≤ 1.21, d _b≤ 1.15, d _b≤ 1.00, d _b≤ 0.90, d _b≤ 0.80, perhaps d even _b≤ 0.70.Reduce d _bCan improve the filtration efficiency of strainer, and the intensity of strainer and substrate applications.

In addition, porous ceramic honeycombs wall of the present invention also comprises preferred orientation, and wherein, the preferred orientation of the cordierite crystal in the honeycomb body structure wall shows △ _I0.1, △ wherein _I=I _T-I _A.Particularly, structure can comprise I _A≤ 0.6, I _A≤ 0.5, perhaps I even _A≤ 0.4.In addition, to the example of orientation, this structure comprises I _T〉=0.7, perhaps I even _A〉=0.8.The CTE that the preferred orientation of the honeycomb of humble cracking has reduced at least one direction.In addition, cordierite structure honeycomb of the present invention also shows that high hole is connective, and connectedness can be by the connective factor in hole (PCF) definition, and this factor is by relational expression PCF=%P/ (d _b) definition, wherein, PCF can be PCF 〉=40%, PCF 〉=45%, PCF 〉=50%, perhaps PCF 〉=55% even.In addition, the embodiment that the present invention selects has confirmed PCF 〉=60%, PCF 〉=70%, PCF 〉=80% or PCF 〉=90% even.

In some embodiments, cordierite bodies can be used for petrolic emission control catalyst carrier as the form (unplugged embodiment) of the honeycomb ceramic base material of circulation base material.To some such application, for example, for being suitable for catalyst stores in the cell walls of honeycomb, honeycomb ceramic may require relatively high porosity.Similarly, require the high wall perviousness (permeability) of relatively high porosity with the ceramic honeycomb body wall-flow filter (particulate filter) of the obstruction that is provided for diesel engine exhaust and processes.In the application of the relative high porosity of this class, the overall porosity of honeycomb ceramic (%P), i.e. %P 〉=46%, perhaps %P 〉=50% even.In some embodiments, confirm %P 〉=55%, %P 〉=60%, %P 〉=65%, perhaps %P 〉=70% even.To some application requiring overall porosity of the quick firing catalyzer circulation base material of thin-walled (as less than 10 mils, less than 7 mils, perhaps even less than 6 mils or 4 mils) greater than 46%, greater than 50%, perhaps even greater than 55%.

According to another aspect, the invention provides the method for making the porous ceramic honeycombs structure, the method comprises the following steps: inorganic raw material, organic binder bond and liquid carrier are mixed, form the batch of material of plasticising, by the batch of material of this plasticising, form the green compact body, the dried body, cure, cordierite ceramic structure is provided, and this structure has relatively low crack splitting and relative high thermal shocking, shows E _Ratio≤ 1.05 and TSP 〉=525 ℃.

According to another aspect, the invention provides the porous ceramic honeycombs structure, this structure comprises main cordierite ceramic phase, and this ceramic phase shows humble cracking, shows △ α _mc≤ 5.0, CTE (25-800 ℃)≤15x10 ^-7/ ℃ and %P 〉=46%.

The accompanying drawing summary

Further describe the present invention referring to the following drawings, wherein:

Fig. 1 be the trichroite embodiment of humble cracking of the present invention during heating and cooling Young's modulus (psi) and temperature (℃) graph of a relation.

Fig. 2 be the Young's modulus (psi) of " prior art " comparative example during heating and cooling with temperature (℃) graph of a relation.

Fig. 3 be to the TSP of the embodiment of the present invention (filled circles and solid triangle) and comparative example (circle) (℃) with the CTE (10 of 25-800 ℃ ^-7/ ℃) graph of a relation.

Fig. 4 be to the TSP of the embodiment of the present invention (filled circles and solid triangle) and comparative example (circle) (℃) with the graph of a relation of the connective factor PCF in hole (%).

Fig. 5 is the graph of a relation to the room temperature MOR/E ratio of the embodiment of the present invention (filled circles and solid triangle) and comparative example (circle) and the connective factor PCF in hole (%).

Fig. 6 is the isometric view (isometric view) of porous honeycomb body base material according to the embodiment of the present invention.

Fig. 7 is the isometric view of porous honeycomb body strainer according to the embodiment of the present invention.

Fig. 8 is to the thermal expansivity of 25-800 ℃ of the embodiment of the present invention (filled circles and solid triangle) and comparative example (circle) and the graph of a relation of axle I-ratio, and described thermal expansivity adds 0.6% (Mu+Sp+Sa+Al) to existing secondary crystal to carry out mutually normalization method by the CTE value to measuring.

Fig. 9 is the △ α to the embodiment of the present invention (filled circles and solid triangle) and comparative example (circle) _mcWith parameter P _MCBetween graph of a relation.

Figure 10 is the E to the embodiment of the present invention (filled circles and solid triangle) and comparative example (circle) _Ratio=E _{1000 ° of C}/ E _{Room temperature}With parameter P _MCBetween graph of a relation.

Figure 11 is MOR/E and the parameter P to the embodiment of the present invention (filled circles and solid triangle) and comparative example (circle) _STBetween graph of a relation.

Figure 12 is the E to the embodiment of the present invention (filled circles and solid triangle) and comparative example (circle) _{1000 ℃ of ratios}With tiny crack parameter N b ³Between graph of a relation.

Figure 13 be to the thermal shock parameter TSP of the embodiment of the present invention (filled circles and solid triangle) and comparative example (circle) (℃) with ° △ α _mc(10 ^-7/ ℃) graph of a relation.

Figure 14 is to the embodiment of the present invention (filled circles and solid triangle) and meets 11 microns≤d ₅₀The MOR/CFA (psi) of the comparative example of≤15 microns (circle) and the graph of a relation between % porosity (%).

Figure 15 is the scanning electron microscope diagram in cross section of polishing of the honeycomb wall of the embodiment of the present invention.

Embodiment

, for guaranteeing relatively low Young's modulus ratio,, by providing by substantially without the crack porous cordierite ceramic material that splits, can make cordierite ceramic honeycomb of the present invention realize E _{Ratio 1000}=E _{H1000 ° of C}/ E _{Room temperature}.E _{Ratio 1000}Value greater than 1.00 but less than 1.05 expression very low levels but admissible crack splitting (referring to Fig. 1), the i.e. essentially no crack honeycombs that split.E _{Ratio 1000}Value greater than the 1.05 relatively high crack levels (Fig. 2) of splitting of expression, for avoiding that product property (as intensity with to the insensitivity of the resistance to sudden heating of catalysis) is had a negative impact, this is undesirable.Fig. 1 be the trichroite (I41) of the humble cracking of the embodiment of the present invention during heating and cooling Young's modulus (psi) and temperature (℃) graph of a relation.In figure, filled circles represents to add dsc data, and hollow square represents cooling data, and the data fitting that the little filled circles in hollow square represents becomes polynomial expression, derives tangent point (hollow triangle) and tangent line (solid line).Open diamonds is the tangent value E ° under room temperature ₂₅.It shall yet further be noted that at this referring to the E between heating period ₂₅, E ₉₀₀And E ₁₀₀₀(at 25 ℃, the Young's modulus of 900 ℃ and 1000 ℃) value.Fig. 2 be the Young's modulus (psi) of " prior art " comparative example (C4) during heating and cooling with temperature (℃) graph of a relation.Filled circles represents to add dsc data, hollow square represents cooling data, and the data fitting that the little filled circles in hollow square represents becomes polynomial expression, derives tangent point (hollow triangle, put C) and tangent line (solid line A-B), open diamonds is the tangent value E ° under room temperature ₂₅.Should also be noted that the E between heating period ₂₅, E ₉₀₀And E ₁₀₀₀(at 25 ℃, the Young's modulus of 900 ℃ and 1000 ℃) value.

Therefore, according to the embodiment of the present invention, require E _{Ratio 1000}Value be less than or equal to 1.05, more requirements definition is E _H1000/ E _{Room temperature}E _{Ratio 1000}≤ 1.01, perhaps E even _H1000/ E _{Room temperature}≤ 1.00.But, according to the embodiment of the present invention, confirm E _{Ratio 1000}≤ 0.98, E _{Ratio 1000}≤ 0.96, E _{Ratio 1000}≤ 0.95, perhaps E even _{Ratio 1000}≤ 0.93.These are all the examples of relatively humble cracking level.With reference to ASTM C1198-01 or in the title that on June 27th, 2007 submitted to, be the common unexamined U.S. Provisional Patent Application No.XX/XXX of " method and apparatus (Methods And Apparatus For Measuring Elastic Modulus Of Non-Solid Ceramic Materials By Resonance) of measuring the Young's modulus of non-solid ceramic material by resonance ", XXX, determine the high-temperature elastic modulus value, the content of the document is by reference to being incorporated into this paper.

The thermal shocking limit (TSL) that it has been generally acknowledged that ceramic honeycomb body of the present invention is 500 ℃ for the ceramic honeycomb body surface temperature, but the top temperature at crackle infringement Shi Qi center does not occur.TSL can estimate by adding 500 ℃ on the thermal shock parameter (TSP) that defines in the above.In other words, TSL=TSP+500 ℃.Therefore, according to another aspect of the present invention, illustrative improved thermal shocking limit (TSL) is the TSP value that embodiment of the present invention realizes, i.e. TSP 〉=400 ℃, TSP 〉=450 ℃, TSP 〉=525 ℃, TSP 〉=550 ℃, and TSP 〉=600 ℃ even.In some embodiments, realize that TSP 〉=700 are ℃ (referring to embodiment 4-6,8-9,11,13-14,27-32,35-39,41-43 and 46), TSP 〉=800 are ℃ (referring to embodiment 4,6,13-15,18,20,27-28,31,36-39 and 41-43), TSP 〉=900 are ℃ (referring to embodiment 14,18,27-28,31,37-38 and 41-42), and even TSP 〉=1000 ℃ (referring to embodiment 18,27 and 41).

In addition, in some embodiments, humble cracking honeycomb of the present invention has realized relatively hanging down simultaneously the good combination of CTE and high TSP.For example,, according to broad aspect of the present invention, by embodiments of the present invention (Fig. 3), realized having TSP 〉=400 ℃ and CTE (25-800 ℃)≤18x10 ^-7/ ℃, perhaps CTE (25-800 ℃)≤15x10 even ^-7/ ℃ the honeycomb of humble cracking of combination.Some embodiment have realized the combination of even lower CTE and Geng Gao TSP.For example,, by many embodiments of the present invention (referring to embodiment 2-9,11-22,27-39 and 41-48), realize TSP 〉=500 ℃ and CTE (25-800 ℃)≤15x10 ^-7/ ℃ combination.In some embodiments, realized TSP 〉=525 ° C and CTE (25-800 ° of C)≤15x10 ^-7The good combination of/° C.In some embodiments, realize TSP 〉=600 ° C and CTE (25-800 ° of C)≤15x10 ^-7/ ° C, perhaps TSP 〉=700 ° C and CTE (25-800 ° of C)≤13x10 even ^-7The combination of/° C.

Cordierite honeycomb bodies of the present invention has the hole of the good connection of a high proportion of narrow pore size distribution, and this character has important effect to the high TSP value (Fig. 4) of observing.These connectednesses of high hole without the crack pottery that splits have the effect of the elastic mould value of reduction, and the degree of its reduction is greater than the MOR value.Therefore, the TSP value depends on MOR _{Room temperature}/ E _{Chamber Temperature}Ratio, this ratio is subject to these without the crack beneficial effect (Fig. 5) of hole configuration that splits pottery., according to embodiments of the invention, provide relatively high MOR _{Room temperature}/ E _{Room temperature}Ratio, wherein, MOR _{Room temperature}/ E _{Room temperature}〉=0.09%, MOR _{Room temperature}/ E _{Room temperature}〉=0.10%, MOR _{Room temperature}/ E _{Room temperature}〉=0.12%, MOR _{Room temperature}/ E _{Room temperature}〉=0.14%, perhaps MOR even _{Room temperature}/ E _{Room temperature}〉=0.16%.Some embodiments show MOR _{Room temperature}/ E _{Room temperature}〉=0.18% (referring to embodiment 27,37-39 and 41), perhaps MOR even _{Room temperature}/ E _{Room temperature}〉=0.19% (referring to embodiment 37,41).

As noted above, the narrow pore size distribution of porous insert hole of the present invention can be by d _f≤ 0.48 and/or d _b≤ 1.65 characterize, wherein d _f=(d ₅₀-d ₁₀)/d ₅₀And d _b=(d ₉₀-d ₁₀)/d ₅₀.Parameter d in these equatioies ₁₀, d ₅₀And d ₉₀Be normally defined in this article, according to standard mercury porosimeter, measure, the difference 10%, 50% of material hole volume and 90% belongs to the more hole of small-bore.Therefore, during these are measured, d ₁₀＜d ₅₀＜d ₉₀.To improved TSP performance, the porosity d-factor (d that realizes by embodiments of the present invention _f) value be d _f≤ 0.45, d _f≤ 0.40, d _f≤ 0.37, d _f≤ 0.35 and d _f≤ 0.30.Some embodiments are realized the very little porosity d-factor (d relatively _f), wherein, d _f≤ 0.28 (referring to embodiment 27,36,39 and 44-45), d _f≤ 0.25 (referring to embodiment 36 and 44-45), perhaps d even _f≤ 0.23 (reference example 44-45).In addition, according to d _b=(d ₉₀-d ₁₀)/d ₅₀The pore size distribution total width of definition is relative narrower also.The d that for example, can realize by embodiment of the present invention _bValue is, d _b≤ 1.65, d _b≤ 1.4, d _b≤ 1.20, d _b≤ 1.00, perhaps d even _b≤ 0.90.Some embodiments show, d _b≤ 0.80 (referring to embodiment 21,27-28,30-31,36,38-39,41-42,44,46), d _b≤ 0.70 (referring to embodiment 27-28,36,44), perhaps d even _b≤ 0.65 (referring to embodiment 27 and 44).

The connective factor in hole (PCF) is by relational expression PCF=% porosity/(d _b) definition, can realize the connective factor (PCF) in relatively high hole by embodiments of the present invention.Therefore, embodiment can reach PCF 〉=40%, PCF 〉=45%, PCF 〉=50%, PCF 〉=55%, perhaps PCF 〉=60% even.Other embodiments show that PCF 〉=70% is (referring to embodiment 14,18,21,27-28,30-31,36,38-39,41-44,46 and 55), PCF 〉=80% is (referring to embodiment 27-28,30,36,38,41-42 and 44), perhaps PCF 〉=90% (referring to embodiment 27-28 and 44) even.

In the high porosity honeycomb according to embodiment of the present invention, namely overall porosity (%P) reaches in the cordierite honeycomb bodies of %P 〉=46%, the mean pore sizes (d of target ₅₀) partly depend on the specific end-use of honeycomb.To use as the circulation honeycomb base material that is used for support of the catalyst the mean pore sizes (d of ceramic honeycomb body of the present invention ₅₀) can, at about 1-30 micrometer range, have d when comprising catalytic material in hole ₅₀〉=10 microns, perhaps even the value of 10-30 micron is useful especially; When requiring 〉=46% high porosity is with the thermal mass that reduces base material and while improving firing characteristic, for example, in unplugged circulation catalyst substrate application, wishes mean pore sizes (d ₅₀) be the 1-10 micron.

On the other hand, with the honeycomb of high porosity as in wall flow particulate filter device (as diesel exhaust filtration application) time, at a small amount of catalyzer of filter load or there is no the situation of catalyzer, mean pore sizes (d ₅₀) can be at the 5-15 micrometer range, when the relatively more substantial catalyzer situation of strainer load, mean pore sizes is at the 15-30 micrometer range.To these two kinds of application, the overall porosity of wall is, for example, %P 〉=46%, %P 〉=50%, %P 〉=55%, perhaps %P 〉=60% even, be %P 〉=65% in some situation, perhaps %P 〉=70% even.In many embodiments of the present invention, honeycomb body structure shows d ₅₀〉=8 microns, and the combination of overall porosity 〉=50%.

Ceramic honeycomb body can be the porous cordierite ceramic honeycomb with many ducts of extending between first end and the second end, for example, and as shown in Figure 6 and Figure 7.Shown in the honeycomb body structure that has of ceramic honeycomb body be suitable for for example circulating catalyst substrate or wall stream exhaust gas particle strainer, as diesel particulate filter.Be shown in Fig. 6 according to the typical porous ceramic honeycombs circulation substrate article 10 of embodiment of the present invention, these goods comprise the duct 11 of many almost parallels, described duct is formed and is limited by it at least partly by the hole wall 14 (perhaps being called " reticulation ") that intersects, and from first end 12, extends to the second end 13.Duct 11 is not stopped up, and from first end 12, directly flows through this duct 11 to second ends 13 downwards.Preferably, honeycomb article 10 also is included in the smooth layer of extruding 15 that forms around this honeycomb body structure, and still, this top layer is optional, can form as after-applied top layer in the processing of back.But with example nonrestrictive mode, for example, the thickness that is used for each hole wall 14 of this base material can be in about 0.002-0.010 inch (approximately 51-253 micron) scope.Hole density is for example 300-900 hole/inch ²(cpsi).In preferred enforcement, poroid honeycomb body structure is comprised of many parallel ducts 11, forms honeycomb body structure, and the cross section in described duct 11 is square roughly.Perhaps, also can use other cross-sectional configuration in honeycomb body structure, comprise rectangle, circle, ellipse, trilateral, octagon, hexagon, or their combination.Be defined as the syndeton in the hole extending longitudinally that is formed by hole wall at this term used " honeycomb ", wherein have general repeat pattern.

Fig. 7 illustrates the honeycomb filter 100 of another aspect of the present invention.This generality structure is identical with the circulation base material, comprises the main body 101 that consists of intersection porous ceramic walls 106, and described porous wall 106 extends to the second end 104 from first end 102.Inlet hole 108 is appointed as in a part of hole, outlet opening 110 is appointed as in some other hole.In strainer 100, comprise tamper 112 in some selected ducts.Generally speaking, tamper is arranged on the end in duct, and with specific arranged in patterns, as directed halma board pattern.Import duct 108 can be stopped up at exit end 104, and outlet duct 110 can be stopped up at entrance end 102.Other obstruction methods can be used,, for gaining in strength, institute's porose (as shown in the figure) of outermost peripheral can be stopped up.Perhaps, some hole can not stopped up in end.In another optional embodiment, some ducts can be flow passage, and some ducts can be stopped up, with the design that provides so-called part to filter.But with example nonrestrictive mode, for example, the thickness that is used for each hole wall 14 of this strainer can be in about 0.010-0.030 inch (approximately 253-759 micron) scope.Hole density is for example 100-400 hole/inch ²(cpsi).

According to comprising humble cracking feature in the crystal microstructure of cordierite ceramic honeycomb provided by the invention, this feature shows E _{Ratio 1000}≤ 1.05, perhaps E even _{Ratio 1000}≤ 1.01, be defined as E _{Ratio 1000}=(E _{1000 ° of C}/ E _{Room temperature}), can also characterize by following character, i.e. the arbitrary orientation of cordierite crystal in honeycomb, the perhaps cleanliness number of preferred crystalline orientation (having preferred orientation), most typical is that crystal z-axle is parallel to the honeycomb wall surface with certain alignment angles.The example of arbitrary orientation is that the cordierite crystal in the honeycomb body structure wall shows △ _I≤ 0.1, △ wherein _I=I _T-I _A.I _TTransversal I ratio, I _AAxial I ratio (referring to following discussion to definition).Embodiment 21-26 illustrates the embodiment of the arbitrary orientation of aspect according to the present invention.On the other hand, the cordierite crystal in humble cracking honeycomb body structure wall of the present invention has preferred orientation, shows △ _I0.1, △ wherein _I=I _T-I _A(referring to embodiment 1-20 and 27-55).In porous ceramic honeycombs according to the embodiment of the present invention, comprise that the honeycomb body structure wall of preferred orientation also comprises I _A≤ 0.6, I _A≤ 0.5, perhaps I even _A≤ 0.4.In addition, the honeycomb body structure wall also comprises I _T〉=0.7, I _T〉=0.8, I _T〉=0.85, perhaps I even _T〉=0.9.Another aspect, the present invention shows that the honeycomb body structure of the humble cracking of preferred orientation can show, at △ _I=I _T-I _AThe time, △ _I〉=0.2, △ _I〉=0.3, △ _I〉=0.4 or △ even _I〉=0.5.

In order to keep good resistance to sudden heating, cordierite ceramic honeycomb should be relatively low at the mean thermal expansion coefficients (following is CTE) of 25-800 ℃ of temperature range.Therefore, embodiments of the present invention show, along the CTE≤18.0x10 of at least one direction of ceramic body ^-7/ ℃ (25-800 ℃).In other embodiments, provide CTE≤16.0x10 along at least one direction ^-7/ ℃ (25-800 ℃), perhaps CTE≤14.0x10 even ^-7/ ℃ (25-800 ℃).In other embodiments of the crack honeycomb that splits, at the thermal expansivity CTE≤12.0x10 of this temperature range cordierite ceramic honeycomb along at least one direction ^-7/ ℃ (25-800 ℃), CTE≤10.0x10 ^-7/ ℃ (25-800 ℃) or CTE≤9.0x10 even ^-7/ ℃ (25-800 ℃).The relatively low crack level of splitting of the present invention generally provides 7x10 ^-7/ ℃≤CTE (25-800 ℃)≤15x10 ^-7/ ℃.According to some embodiments, the crack honeycomb that provides that splits has 9x10 ^-7/ ℃≤CTE (25-800 ℃)≤15x10 ^-7/ ℃, perhaps 10x10 even ^-7/ ℃≤CTE (25-800 ℃)≤15x10 ^-7/ ℃.In other embodiments of the present invention, CTE can be, CTE (25-800 ℃) 〉=0.20 (%P)-4.5, perhaps CTE (25-800 ℃) 〉=0.20 (%P)-3.0 even.

The CTE of cordierite bodies is determined by following characteristic to a great extent: the CTE that cordierite crystal is intrinsic, the overall angle of the structure orientation on the direction of measuring ceramic body CTE of the cordierite crystal in pottery, the amount of secondary crystal phase in ceramic body, and the crack degree of splitting in ceramic body.Therefore, can independently assess these and act on ceramic honeycomb body each factor along the CTE of assigned direction.

Find, excessively form secondary crystal phase (as mullite, spinel, sapphirine and corundum) and all CTE can be increased to higher value in these potteries, therefore, if can avoid excessively forming secondary crystal phase.In fact, observing average CTE is mainly that the total amount of remaining mullite+spinel+sapphirine+corundum in the ceramic body of trichroite increases with being present in, and increment rate is every 1% these secondary crystal 0.6x10 that make an appointment ^-7/ ℃." normalized " CTE is corresponding to the component of a thermal expansivity owing to the trichroite phase, and therefore " normalized " CTE can be calculated as CTE-0.6 (% level crystal phase).Therefore, for realizing favourable relatively low CTE, total body burden of these secondary crystal phases should be less than 6%, perhaps even less than 4%.

The inventor also finds, there is no crack splitting or the situation of secondary crystalline phase, at 25-800 ℃, cordierite honeycomb bodies at the CTE of orifice throat length direction (" axially " CTE) by relational expression CTE=76.8 (I _A) ³– 129.5 (I _A) ²+ 97.9 (I _A)-12.8 and this axial XRD I-ratio I _ARelevant, axial I-ratio I in this relational expression _A=I (110)/[I (110)+I (002)] is that the X-ray diffraction figure (Fig. 8) that the cross section perpendicular to honeycomb channels length carried out according to known practice is definite.Another kind of metering system to cordierite crystal orientation in honeycomb is transversal I-ratio (I _T), this ratio is that peak intensity compares I _T=I (110)/[I (110)+I (002)], determine by the lip-deep X-ray diffraction that cures at the honeycomb channels wall.

Generally acknowledge that too low CTE generally is illustrated in cordierite honeycomb bodies excessive crack splitting arranged, because crack splitting may be damaged intensity and resistance to sudden heating (TSR) and should be avoided.Find no matter whether to comprise secondary crystal phase in the cordierite honeycomb bodies pottery, its crack degree of splitting can be with the sub-△ α of thermal expansion difference reason _mcReflection, △ α _mcBe defined as follows:

△α _mc=[76.8(I _A) ³–129.5(I _A) ²+97.9(I _A)-12.8]+0.6%(Mu+Sp+Sa+Al)-CTE,

Wherein, % (Mu+Sp+Sa+Al) is the summation of the mullite, spinel, sapphirine and the corundum weight percentage that exist in honeycomb, I _AAxial I-ratio as above.Fig. 8 illustrate trichroite of the present invention and comparative example trichroite secondary crystal has been carried out normalized CTE(mutually is CTE – 0.6 (%Mu+Sp+Sa+Al)) with the axial graph of a relation of I-ratio.To each example, the distance of normalized CTE below the curve of this CTE and axial I-ratio is equivalent to △ α _mcValue.

According to another aspect of the present invention, comprise honeycomb arbitrary orientation in wall of cordierite crystal, as working as, show △ _I≤ 0.1 o'clock, △ wherein _I=I _T-I _A, the CTE of this honeycomb can be less than 18x10 ^-7/ ℃ (25-800 ℃), the scope of example embodiment is 12x10 ^-7/ ℃ to 18x10 ^-7/ ℃ (25-800 ℃), many situations are less than 16x10 ^-7/ ℃ (25-800 ℃) is even perhaps 12-15x10 ^-7/ ℃ (25-800 ℃).

For purpose described herein, the reference intention of cordierite ceramic body or honeycomb is comprised object or the honeycomb of similar physical character, also comprise " (stuffed) of filling " trichroite.The trichroite of filling is the trichroite that has following molecule for example or element in the site, duct of trichroite lattice: H ₂O, CO ₂, Li, K, Na, Rb, Cs, Ca, Sr, Ba, Y or lanthanon, these components provide the improved character useful to some application, as improved coking property or reduction lattice thermal expansion or thermal expansion anisotropy.Also comprise and followingly basic trichroite component is carried out Fe because of some reason, Mn, Co, Ni, Zn, Ga, the chemistry of Ge etc. replaces the trichroite that forms, and described reason is for example improved coking property, color, electrical property or catalytic property.

Aspect another of broad sense, the present invention includes the method for making porous cordierite ceramic honeycomb structure as described above.According to the method, with MgO, Al ₂O ₃, SiO ₂Or the inorganic raw material source of their combination and organic binder bond, liquid carrier and one or more optional components be mixed to form the batch of material of plasticising, and described optional components comprises pore former, softening agent and lubricant.Then, the batch of material of plasticising, by as extrusion molding, is formed green honeycomb.Then, dry these green honeycomb,, as dry by microwave or RF, cure in kiln, with the whole cordierite ceramic honeycomb of inorganic raw material source sintering or reaction-sinter into.The green compact body cures the regular hour in certain temperature, and described temperature and time is enough to provide the cordierite honeycomb bodies of sintering, and described honeycomb has relatively low crack split and by realizing E _Ratio≤ 1.05 have relative high thermal shocking with TSP 〉=525psi.

The inorganic component that is suitable as the raw material of the batch of material that mixes this class plasticising comprises natural or synthetic cordierite powder, and can form without the inorganic powder of the cordierite bodies that ftractures or the combination of inorganic powder by pyroreaction.Example comprises: (1) cordierite powder, also referred to as " grog (grog) ", mainly is comprised of the trichroite phase ceramics; (2) aluminum magnesium silicate base glass powder, also referred to as frit; (3) each particle comprises the powder that can react the heterogeneous aggregation that forms trichroite; (4) two or more form the mixture of different powder, and various powder can be single-phase powder or Multiphase Powder; (5) the aluminum magnesium silicate powder of chemical precipitation, if reaction forms the sol-gel powder of cordierite microstructure.

The median particle diameter of powder is unimportant; Can be routinely with particle size adjustment to effectively providing the finished product to be suitable for the mean pore sizes of application-specific.For example, when described application was substrate for catalytic converters, the mean pore sizes of raw material can be between the 2-20 micron.When described application was diesel particulate filter, mean pore sizes can be between the 15-50 micron.But, usually preferably make the size distribution of inorganic powder or inorganic powder combination narrower, provide narrow pore size distribution to be preferably baked body, high hole connectedness and high MOR/E ratio.

The body that should regulate the raw material that exists in initial powder forms (bulk composition) and (does not comprise volatiles, as H ₂O, CO ₂, SO ₂And organism), clean oxide compound is formed and be about 48-54%SiO ₂, 33-37%Al ₂O ₃And 11-16%MgO, but the accumulating weight of these three kinds of oxide compounds accounts for and does not comprise at least 95% of volatilization or the batch of material gross weight of evaporated components.Preferably, regulate the ratio of these oxide compounds, make main body after curing by at least 90 % by weight trichroites, perhaps even 95 % by weight or 97 % by weight trichroites form.

Be present in other components in these batch of materials with small proportion and comprise the oxide compound of impurity element or have a mind to doping agent, as, calcium, iron, titanium, sodium, potassium, boron, tungsten, bismuth etc.Ratio to magnesium oxide, aluminum oxide and silicon oxide component in the bulk stock mixture is selected, only to form stoichiometric trichroite, perhaps can select, can form some spinel, sapphirine, mullite, forsterite, enstatite or glassy phase.But, CaO+Na ₂O+K ₂The O sum can, perhaps even less than 0.5 % by weight, should be restricted to the cristobalite that forms in main body less than 1.0 % by weight less than 1.0 % by weight, does not perhaps preferably exist fully.

When selecting the synthesis of dichroite powder to be used for batch of material, when the larger trichroite particle that is preferably greater than 20 microns, preferred trichroite particle is not single crystal particle, but preferably comprises the polycrystalline aggregate of cordierite crystal.Cordierite crystal can be with respect to intragranular adjacent crystal arbitrary orientation.If the trichroite feed particles comprises all or part of " domain structure " with parallel-oriented crystal close to each other in a domain structure, these domain structure should be not more than approximately 20 microns, and some situation is not more than 10 microns.

The cordierite powder that is fit to predetermined purpose can for example obtain in the following manner: make the inorganic precursor material, comprise mineral assemblage, as clay+talcum+aluminum oxide, spinel+silicon oxide, magnesium oxide+aluminum oxide+silicon oxide, forsterite+kaolin etc. carry out pre-reaction wholly or in part, perhaps make partially or completely devitrification (crystallization) of aluminium-magnesium silicate glass material; Perhaps make the aluminium of chemical precipitation-Magnesium Silicate q-agent material such as partially or completely crystallization of collosol and gel powder.Perhaps, can use the trichroite of natural generation, they are crushed to suitable granularity.

When making the inorganic mineral raw material reaction or by the material of chemical precipitation, preparing cordierite powder, for example can form in the following manner: the precursor that preparation mixes or the object of chemical precipitation, heat this object to the temperature that is enough to form trichroite, then this object is pulverized, by optional screening or air classification, reached required granularity.Perhaps, raw material or throw out also can carry out pre-efflorescence by nodularization,, for example by spraying drying or other atomising methods, the particulate that produces are heated to effectively form the temperature of trichroite.When by glass precursor, preparing cordierite powder, melten glass is configured as easily shape and pulverizes, perhaps by melten glass being poured in quench liquid such as water, carry out " drigaged ".Then select suitably essential size range by optional screening or air classification, the glass feed that forms is crushed to desired particle size.

When the granularity that requires final glass greater than approximately 20 microns the time, glass can contain nucleator such as titanium oxide, promote the trichroite nucleation with the many positions in whole glass particle inside during devitrification afterwards, to prevent from forming the crystalline region structure (crystal domain) greater than 20 microns.Then heat this glass powder, to carry out nucleation by devitrification or " ceramic " and to make the trichroite growth.Randomly, after heating, the glass of devitrification is carried out other powder treatment to obtain desired particle size, distribute.

According to preferred batch of material method, the mixture of inorganic raw material comprises talcum, aluminum oxide and forms source, silicon oxide and form source and optional kaolin or the kaolin of calcining.In particular implementation, this raw mix also comprises colloidal metal oxide source.Colloidal metal oxide source can preferably form colloidal suspension in solvent, this colloidal state oxide source comprises 0-97 % by weight SiO ₂, 0-97 % by weight MgO, 0-97 % by weight Al ₂O ₃, and one or more metal oxides of group under being selected from of at least 3.0 % by weight: Li ₂O, Na ₂O,K ₂O, CaO, Fe ₂O ₃And TiO ₂.Metal oxide also comprises at least 4%, at least 5%, perhaps the colloidal metal oxide source of at least 6 % by weight even.According to embodiment, colloidal metal oxide source can comprise and contains at least 50 % by weight SiO ₂Collodial silica salt face (when with anhydrous benchmark calculational chemistry formula).For example, colloidal silicate can be colloidal state phyllosilicate (phyllosilicate), as attapulgite or wilkinite.According to other embodiment, the mixture of inorganic raw material can comprise nucleator, with promote trichroite by the reaction of inorganic raw material nucleation.A kind of useful nucleator is the cordierite powder of pre-reaction.

Except the inorganic raw material mixture, batch of material also comprises pore former.Pore former as append thing can account for inorganic raw material weight more than or equal to 50 % by weight, perhaps 60 % by weight even.Pore former can comprise for example combination of graphite and starch.Starch can comprise W-Gum or yam starch.In the situation of the combination of using graphite and starch, pore former is as the thing that appends take inorganic raw material as 100 % by weight as benchmark, comprises more than or equal to 40% graphite with more than or equal to 10% starch.

Embodiment according to described method,, for preparation has humble cracking and high strain tolerance (MOR/E) and therefore produces the ceramic honeycomb article of high TSP, should suitably select some component of batch of material, particularly, the inorganic raw material of raw material and pore former, and suitably control baking conditions.Find realization factor P _MC≤ 5.0 can produce very low crack splitting (Fig. 9 and Figure 10), and realization factor P _ST〉=0.090 can produce high strain tolerance (MOR/E), therefore can realize high TSP (Figure 11) in honeycomb article.P _MCAnd P _STBe defined as follows:

P _MC((aluminum oxide forms the d in source to the kaolin) – 0.00870 of % by weight calcining (the % by weight aluminum oxide forms source) to=7.06+0.164 (% by weight feed kaolin)+0.095 ₅₀) – 0.0657 (% by weight pore former)+0.022 (heating rate of 800-900 ℃)+0.025 ((1350 ℃-T of the heating rate) – 0.018 of 1200-1300 ℃ _{The highest}Heating rate) – 0.462 (% by weight colloidal metal oxide source), and

P _ST=0.067+0.000967 (% by weight pore former) – 0.00000516 (% by weight the pore former) (d of pore former ₅₀) (kaolin of % by weight kaolin+% by weight calcining)+(aluminum oxide forms the d in source to 0.0000502 (the % by weight aluminum oxide forms source) to – 0.000921 ₅₀) – 0.0000143 (% by weight the talcum) (d of talcum ₅₀)+0.00392 (% by weight colloidal metal oxide source).

, for reaching relatively low crack splitting, can provide P _MC≤ 3.0, P _MC≤ 2.0, perhaps P even _MC≤ 1.0.Similarly, for reaching relatively high strain tolerance (MOR/E) and therefore producing relatively high TSP, P _ST〉=0.100, P _ST〉=0.120, perhaps P even _ST〉=0.140.In order to obtain relatively low CTE (25-800 ℃), raw mix can not have trichroite or other trichroite nucleators of pre-reaction.

In other embodiments, described method comprises the inorganic raw material that does not contain kaolin or calcined kaolin.Not containing kaolin or calcined kaolin can provide than the crack of low degree and split, and pore size distribution is narrowed down.Similarly, raw mix can not contain median particle diameter less than aluminum trihydrate [gibbsite or the Al (OH) of 4 microns ₃], yet can not provide than the crack of low degree and split because do not contain tiny aluminum trihydrate.In addition, raw mix can not contain kaolin or calcined kaolin, and may further include talc source, one or more aluminum oxide form source, and silicon oxide forms source, at least 20 % by weight pore formers, with the colloidal state phyllosilicate of 0-10 % by weight, it can contain (the Li of at least 4 % by weight ₂O+Na ₂O+K ₂O+CaO+Fe ₂O ₃+ TiO ₂).Exist the colloidal state phyllosilicate can help to introduce impurity, therefore, can help to produce more glassy phase, glassy phase generally can reduce crack splitting.According to other embodiment of the present invention, talc source forms source with silicon oxide separately can be relative tiny, and median particle diameter is less than 12 microns, and the colloidal state phyllosilicate can account at least 3 % by weight, and the median particle diameter of pore former is not more than 40 microns.According to other embodiments, talc source and silicon oxide form source median particle diameter separately and are at least 12 microns, and are not more than 35 microns, and the median particle diameter of each pore former is not less than 30 microns and be not more than 60 microns.

Table 1-18 below outside (the present invention) and scope, the example of the cordierite ceramic of (comparative example is marked with C) is listed within the scope of the present invention.These examples comprise having different porosities, pore size distribution, the connective degree in hole (by the PCF that changes, being derived), and the material of the strength of materials (MOR) and thermal properties (CTE, etc.).Table 1 comprises the various raw materials be used to the batch of material of preparing porous ceramic honeycombs of the present invention.The batch composition that is used for various embodiments of the present invention is listed in table 3-9.Unless otherwise noted, otherwise to all granularities that raw material is listed, be all to obtain by laser-diffractometer (as little extraction section's grain analyser (Microtrac particle analyzer) of model FRA9200 or model S3000 (little extraction section company product)).Table 11-18 comprises the relevant physical properties of the example embodiment of the cordierite ceramic honeycomb product of humble cracking of the present invention, measures and by these observed values, calculated.The character of comparative example is listed in table 10.These values comprise the volume % porosity (%P) of each material, the different pore size of material (as, d ₁, d ₁₀, d ₅₀, d ₉₀Deng), be defined as d _f=(d ₅₀-d ₁₀)/d ₅₀The porosity d-factor (d _f), be defined as d _b=(d ₉₀-d ₁₀)/d ₅₀The porosity width factor (d _b), the connective factor in hole (PCF) (is defined as PCF=%P/ (d _b)), honeycomb is at each thermal expansivity observed value of differing temps scope (25-800 ℃, 500-900 ℃ and 200-1000 ℃), owing to crack thermal expansion difference reason (the Δ α that splits _mc), at transversal I-ratio (I of each situation mensuration of extruding honeycomb shaped to material _T) and axial I-ratio (I _A), and I ratio difference (Δ I) (is defined as △ I=I _T-I _A), the secondary crystal phase mullite that exists in material, the percentage of spinel+sapphirine and aluminum oxide (forming the retained percentage of trichroite phase and intercrystalline glass), (unit is cpsi or number of pores per inch to the hole density of the poroid honeycomb ceramics sample that this material is made ²The honeycomb cross section) and wall thickness (unit is mil or thousand/inch), closed forward position area (Closed Frontal Area) (CFA), room temperature rupture modulus intensity (MOR), the ratio (MOR/CFA) of room temperature rupture modulus intensity and closed forward position area, each material that the honeycomb ceramics sample of this material is measured during heating differing temps (at RT (25 ℃), at 900 ℃ and 1000 ℃) under Young's modulus (psi), at the E of differing temps (900 ℃ and 1000 ℃) _Ratio, tiny crack parameter N b ³(by following definition), room temperature (25 ℃) strain tolerances (MOR/E), the thermal shock parameter of material (TSP) and thermal shocking limit (TSL), wherein TSP is defined as TSP=MOR _{Room temperature}/ [E _{Room temperature}] [CTE _H], (E _{Room temperature}) be the room temperature Young's modulus, (MOR _{Room temperature}) be room temperature rupture modulus intensity, (CTE _H) be high temperature (500-900 ℃) thermal expansivity.TSL is defined as TSL=TSP+500 ℃., according to the nearly skin temperature of 200 ℃, also calculated thermal shock parameter, TSP ^*=MOR _{Room temperature}/ [E _{Room temperature}] [CTE _{200-1000 ° of C}], corresponding thermal shocking limit TSL ^*=TSP ^*+ 200 ℃ is top layer while being 200 ℃, the estimated temperature that can be heated at the core body that there is no honeycomb under cracked condition.

The crack parameter N b that splits ³To the crack measurement of splitting level in ceramic body such as cordierite ceramic.Inventor's discovery, to the cordierite bodies of humble cracking, Young's modulus generally raises and reduces gradually with temperature.It is believed that, reducing of this Young's modulus is because due in crystalline structure, the distance between atom increases with the temperature rising.Porous is shown in Fig. 1 without the crack Young's modulus that splits cordierite honeycomb bodies with the example that the temperature rising reduces.Fig. 1 illustrate the cordierite honeycomb bodies pottery (embodiment of the present invention 42) that splits without crack be heated to 1,200 ℃ (filled circles) and cooling during getting back to room temperature (hollow square) Young's modulus and the variation relation of temperature.In fact the heating and cooling trend curve does not exist tiny crack near overlapping expression.Discovery is from room temperature to 900 ℃, perhaps even to 1000 ℃ Young's modulus reduce basic for linear.Higher than approximately 1,000 ℃, the speed example increasing that Young's modulus rises and reduces with temperature.It is believed that its reason is that a small amount of residual glassy phase occurs softening, perhaps partial melting even, glassy phase reacts formation by impurity at first during ceramic post sintering.Surprised is, finds without the crack cordierite ceramic that splits, and Young's modulus is with E °/△ of the velocity of variation △ T of heating and without crack elastic modulus E ° while splitting the body room temperature _{Room temperature}Be directly proportional, and near EQ relational expression 1:

△ E °/△ T=-7.5x10 ^-5(E ° _{Room temperature}) EQ.1

The subscript of springform quantifier (E °) " ° " expression pottery is without the crack Young's modulus that splits state.According to EQ.1, can calculate the ratio of without the crack cordierite bodies that the splits Young's modulus when 900 ℃ or 1000 ℃ and the Young's modulus during at 25 ℃ without the crack cordierite bodies that splits, be E _{900 ° of C}/ E _{Room temperature}=1+875 (7.5x10 ^-5)=0.934 or E _{1000 ° of C}/ E _{Room temperature}=1+975 (7.5x10 ^-5)=0.927.E° _{900 ° of C}/ E ° _{Room temperature}With E ° _{1000 ° of C}/ E ° _{Room temperature}Value provide a baseline, the E of the ceramic body that can more crackly split with respect to this baseline _{900 ° of C}/ E _{Room temperature}With E ° _{1000 ° of C}/ E ° _{Room temperature}Value.To without the crack cordierite bodies that splits, be heated to high temperature as basic identical to compliance and the temperature compliance between initial heating period of temperature in the Young's modulus of cooling period after 1200 ℃, therefore, at any assigned temperature, the elastic mould value of cooling period and its during heating elastic mould value at this temperature are almost identical.This also can be by illustrating shown in humble cracking cordierite ceramic body in Fig. 1.

Temperature compliance to the Young's modulus of the highly crack cordierite ceramic body that splits is shown in Fig. 2.Therefore, Fig. 2 illustrate the cordierite honeycomb bodies pottery (comparative example C4) that splits crack be heated to 1,200 ℃ (filled circles) and more cooling Young's modulus during getting back to room temperature (hollow square) with respect to the performance of temperature variation.Straight line A-B representative is at the tangent of Young's modulus cooling curve C point (hollow triangle), at the slope of this point curve, equals-7.5x10 ^-5(E ° _{Room temperature}), and E ° _{Room temperature}The value of positive tangent at room temperature point.

Young's modulus increases gradually, then, with temperature, rises to 1,200 ℃, more sharply increases.Can think that this increase is because tiny crack is again closed with heating, final annealing (annealing), make ceramic body reduce gradually due to unlimited tiny crack at comparatively high temps.E has larger increase because of the crack minimizing of splitting, the degree that the degree of this increase reduces with heating over the E that makes up each cordierite crystal, the higher object of rigidity while causing high temperature.When pottery was cooling from 1,200 ℃, tiny crack did not ftracture at once again, because microstress is at first very little.As a result, Young's modulus is the trend of splitting cordierite bodies without crack with the trend of cooling generation at first.During beginning, this increase is sharply,, because the viscosity of any liquid or glassy phase increases, may follow respectively because crystallization or devitrification reduce the volume fraction of liquid or glass.In the embodiment of Fig. 2, approximately 1, between 000-800 ℃, E descends more mild increase with temperature may be owing to the Young's modulus of cordierite crystal with cooling increase naturally.Lower than the about temperature of 800 ℃, Young's modulus with cooling generation gradually, then reduce faster.This is because tiny crack progressively ftractures again, and reduces the rigidity of pottery.In room temperature, Young's modulus is got back to and is proceeded to the heat cycle of the initial value before of 1200 ℃ near pottery.

In cordierite ceramic, the crack degree of splitting is reflected in two features of heating and cooling curve of Young's modulus.A crack performance splitting degree is Young's modulus from 25 ℃ to 900 ℃ or the increase degree between the heating period of 1000 ℃, because think that the increase of Young's modulus is closed the causing again by tiny crack.For example, in Fig. 2, to heating curve, E _{1000 ° of C}/ E _{Room temperature}Ratio is 1.49.This numerical value is much larger than 0.927 value of there is no crack splitting fully time expection.Therefore, to the E of cordierite ceramic _{1000 ° of C}/ E _{Room temperature}Value can be with the crack quantitative measurement of splitting degree of doing the room temperature ceramic body.

The heating curve that crack another sign that splits degree is Young's modulus and the interval between cooling curve.The quantitative method of this hysteresis phenomenon is based on sample still to be in not crack temperature range while splitting state cooling curve is carried out tangent.In Fig. 2, tangent is shown line segment A-B, and positive point of contact is designated as point " C ".Therefore, the slope of positive tangent equals to split the dependence of the Young's modulus of cordierite bodies to temperature without crack, as is subjected to the restriction of EQ1.And the value that this positive tangent extension is back to room temperature (some A) approximates the room temperature Young's modulus (if under this sample room temperature, crack splitting not occurring) of sample, and equals the E ° of this sample _{Room temperature}.Therefore, drawn the equation of positive tangent by following general general formula:

E° _Tangent=(E ° _{Room temperature}) { 1-7.5x10 ^-5(T-25) } EQ.2

In fact, the inventor has designed a kind of analytical procedure, with the test measurements of the Young's modulus from cooling period after being heated to approximately 1200 ℃, determines E ° _{Room temperature}.According to this method, will be approximately 1, the Young's modulus observed value that 000-500 ℃ of cooling period records fits to second order polynomial, as temperature (℃) variable.This equation is following form:

E=c+b(T)+a(T ²) EQ.3

In fact, the upper limit to the temperature range of the experimental measurement elastic mould value that fits to EQ.3, if determined that the temperature variant trend of E is at approximately 1000 ℃ or lower than about 1000 ℃ of curvature that demonstration is very high, reason is the softening of for example glassy phase or forms a small amount of liquid, and the described upper limit also is limited in the temperature lower than 1000 ℃.Equally, lower limit to the temperature range of the experimental measurement elastic mould value that fits to EQ.3, if determined that the temperature variant trend of E is at approximately 500 ℃ or higher than about 500 ℃ of curvature that demonstration is very high, reason is the cracking again of tiny crack for example, and described lower limit further is limited in the temperature higher than 500 ℃.Adopt least square regression (least-squares regression) analytical procedure, draw regression coefficient " a, " " b, " in EQ.3 and the value of " c ".

Obtain in the following manner E ° _{Room temperature}Value: solve Young's modulus and temperature when the polynomial curve of the positive tangent that is drawn by EQ.2 and the data fitting of the Young's modulus by cooling period that is drawn by EQ.3 intersects.Be expressed as respectively E at the Young's modulus of this joining and the value of temperature _iAnd T _i.In the example of Fig. 2, E _iAnd T _iValue corresponding to this trilateral, namely put C.Share because this joining is positive tangent and polynomial curve, observe following formula:

E _i=(E ° _{Room temperature}) { 1-7.5x10 ^-5(T _i-25) }=c+b (T _i)+a (T _i ²) EQ.4

In addition, in points of tangency, the slope of polynomial curve must equal the slope of positive tangent.Therefore, observe following formula:

(E ° _{Room temperature}) (7.5x10 ^-5)=b+2a (T _i) EQ.5

EQ.4 and EQ.5 provide two with two unknown quantity E ° _{Room temperature}And T _iInter-related equation.For solving E ° _{Room temperature}And T _i, at first EQ.5 is reset, draw:

(E ° _{Room temperature})={ b+2a (T _i)/(7.5x10 ^-5) EQ.6

Then, with EQ.6 substitution EQ.5, draw following formula:

{{b+2a(T _i)}/(-7.5x10 ^-5)}{1-7.5x10 ^-5(T _i-25)}=c+b(T _i)+a(T _i ²) EQ.7

EQ.7 is reset, draws following formula:

0={c+b(T _i)+a(T _i ²)}-{{b+2a(T _i)}/(-7.5x10 ^-5)}{1-7.5x10 ^-5(T _i-25)} EQ.8

Every in set EQ.8, draw following relational expression:

0={c-{b/(-7.5x10 ^-5)}{1+7.5x10 ^-5(25)}}+(T _i)(b)–(T _i){2a/(-7.5x10 ^-5)}{1+7.5x10 ^-5(25)}–(T _i){{b/(-7.5x10 ^-5)}{-7.5x10 ^-5}}+(T _i ²){a–{2a/(-7.5x10 ^-5)}(-7.5x10 ^-5)} EQ.9

Further simplify EQ.9, draw:

0={c-{b/(-7.5x10 ^-5)}{1+7.5x10 ^-5(25)}}+(T _i){-2a/(-7.5x10 ^-5)}{1+7.5x10 ^-5(25)}+(T _i ²)(-a) EQ.10

EQ.10 can be expressed as again

0=C+B(T _i)+A(T _i ²) EQ.11

In formula, C={c-{b/ (7.5x10 ^-5) { 1+7.5x10 ^-5(25) } },

B={-2a/(-7.5x10 ^-5)}{1+7.5x10 ^-5(25)}，A=-a。Then,, by solving this quadratic equation, draw T _iValue:

T _i={-B+{B ²-4(A)(C)} ^0.5}/2A EQ.12

T _i={-B-{B ²-4(A)(C)} ^0.5}/2A EQ.13

EQ.12 and EQ.13 provide two possible T _iValue, wherein only have one to have the physics actual value, namely at 25-1, and 200 ℃ of values that scope is interior.Then, with the T that calculates in this manner _iPhysics actual value substitution EQ.6, calculate E ° by EQ.6 _{Room temperature}Value.

Solve E ° _{Room temperature}After value, to supposing without the elastic modulus E ° of the crack sample that splits at 25 ℃ _{Room temperature}With the crack sample that splits at 25 ℃ of actual elastic mould value E that record _{Room temperature}Ratio and the original sample crack degree of splitting before heating be directly proportional.That is, the crack degree of splitting of room temperature reduces E than conference _{Room temperature}Value, therefore improve E ° _{Room temperature}/ E _{Room temperature}Value.

Modeling to the relational expression between Young's modulus and crack splitting provides E ° _{Room temperature}/ E _{Room temperature}Ratio and Nb ³Relational expression between quantity, wherein N is the tiny crack quantity in the unit volume pottery, b be tiny crack diameter (referring to D.P.H.Hasselman and J.P.Singh, " Analysis of the Thermal Stress Resistance of Microcracked Brittle Ceramics, " Am.Ceram.Soc.Bull., 58 (9) 856-60 (1979) .).Particularly, this relational expression can be expressed as following formula:

Nb ³=(9/16) { (E ° _{Room temperature}/ E _{Room temperature})-1} EQ.14

Although according to many simplification imaginations, Nb ³Quantity (being called " tiny crack parameter " herein) provides the crack quantitative another kind of useful mode of degree of splitting in ceramic body.To without the crack body that splits, Nb ³Value is 0.00.In the example of Fig. 2, Nb ³Value is 0.56.Tested and determined E _{1000 ° of C}/ E _{Room temperature}Ratio and Nb ³Be directly proportional, E _{1000 ° of C}/ E _{Room temperature}≤ 1.01 value is roughly corresponding to Nb ³≤ 0.08 value.E _{1000 ° of C}/ E _{Room temperature}Be that 1.05 value is equal to Nb ³Be about 0.10 value.E _{1000 ° of C}/ E _{Room temperature}With Nb ³Relation be shown in Figure 12.

Operable according to aspects of the present invention suitable batch of material raw material is listed in following table 1.

Table 1 – batch of material raw material

Table 2 – porous cordierite ceramic comparative example

Table 3-porous cordierite ceramic batch composition of the present invention embodiment

Table 4 – porous cordierite ceramic batch composition of the present invention embodiment

Table 5 – porous cordierite ceramic batch composition of the present invention embodiment

Table 6 – porous cordierite ceramic batch composition of the present invention embodiment

Table 7 – porous cordierite ceramic batch composition of the present invention embodiment

Table 8 – porous cordierite ceramic batch composition of the present invention embodiment

Table 9 – porous cordierite ceramic batch composition of the present invention embodiment

By as can be known top, can be by the organic materials described in this paper table 3-9 and preparing the batch the present invention of inorganic materials.Table 10-18 below the character of comparative example and embodiments of the invention is listed in.

The character of table 10 – porous cordierite ceramic comparative example

Table 11 – porous cordierite ceramic embodiment of the present invention character

Table 12 – porous cordierite ceramic embodiment of the present invention character

Table 13 – porous cordierite ceramic embodiment of the present invention character

Table 14-porous cordierite ceramic embodiment of the present invention character

Table 15-porous cordierite ceramic embodiment of the present invention character

Table 16-porous cordierite ceramic embodiment of the present invention character

Table 17-porous cordierite ceramic embodiment of the present invention character

Table 18-porous cordierite ceramic embodiment of the present invention character

Above in table 9 example C1-C4 (mark C represents comparative example) conventional character of the crack cordierite ceramic that splits that uses in " prior art " ceramic honeycomb body is described.Axial △ α in these embodiment _mcValue shows has the crack of extensive level to split.Table 3-9 (batch of material) and the embodiment of the present invention 1-55 that shows to list in 11-18 (character) have the crack representative of splitting with the ceramic honeycomb body of relative high thermal shocking value of relative low degree, these ceramic honeycomb bodies also have higher thermal expansivity (with the highly crack cordierite material that splits, comparing), as CTE, are 7x10 ^-7/ ℃ to 15x10 ^-7/ ℃ (25-800 ℃).

Crack parameter (the △ α that splits of Δ CTE _mc) value also show relatively low-level crack splitting less than 5.0.The △ α of lower (just less) value _mcShow and probably exist the crack of relatively low degree to split in main body.△ α _mcValue≤4.8, △ α _mc≤ 3.5, △ α _mc≤ 3.0, perhaps △ α even _mc≤ 2.0 expression the crack of minute quantity split, and common relevant to higher TSP (Figure 13).When very low crack the splitting of hope, embodiments of the present invention can provide even △ α _mc≤ 1.0.

The crack another kind sign that splits degree that exists in honeycomb wall is E _{Ratio 1000}Or E _{Ratio 900}, wherein, E _{Ratio 1000}=E _{1000 ° of C}/ E _{Room temperature}, E _{Ratio 900}=E _{900 ° of C}/ E _{Room temperature}, E _{Room temperature}The room temperature Young's modulus, E _{900 ° of C}The Young's modulus in the time of 900 ℃, E _{1000 ℃}It is the Young's modulus in the time of 1000 ℃.Fig. 8 illustrates " normalized " CTE value (25-800 ℃) (that is, to the secondary expansion [% phase] of adjusting mutually) and the axial I-ratio (I that measures to the embodiments of the invention of appointment _A) curve, show the Embodiment C 1-C3 in 10-16 and the crack difference of splitting between the embodiment of the present invention at table.Trend curve in Fig. 8 represents the approximate trend to the CTE without the crack cordierite honeycomb bodies that splits that there is no secondary phase and axial I-ratio.Should be understood that and wish by E _{Ratio 1000}≤ 1.05 value realizes low-level crack splitting., by embodiments of the present invention, can realize E _{Ratio 1000}≤ 1.01, E _{Ratio 1000}≤ 1.00, E _{Ratio 1000}≤ 0.97, E _{Ratio 1000}≤ 0.95, E _{Ratio 1000}≤ 0.93, perhaps E even _{Ratio 1000}≤ 0.90.Many embodiments of the present invention can realize E _Ratio≤ 1.00 and TSP 〉=600 ° C, perhaps E even _Ratio≤ 0.97 and the desirable combination of TSP 〉=700 ℃.Figure 12 illustrates stupalith to humble cracking at E _RatioAnd Nb ³Between good correlation.Therefore, the E of mensuration _RatioIt is the crack best quantitive measure of splitting quantity to existing in honeycomb body structure.

For example draw the figure of the MOR/E data of the strain tolerance (MOR/E) calculated from table 10-17 and other cordierite ceramics outside the scope of the invention with respect to the connective factor in hole (PCF) of Fig. 5.By these data clearly, high-caliber hole connective (showing as relatively high PCF) may obtain relatively high MOR/E value with the relative low-level crack combination of splitting.This relatively low crack splitting with the combination of relative high PCF is of value to the relatively high resistance to sudden heating of acquisition.For example, the embodiment of the humble cracking of the present invention in square frame B is in higher MOR/E, and this MOR/E value, greater than the more crack comparative example that splits in square frame A, proves and reduce the crack benefit of splitting when increasing MOR/E.Equally, in square frame C the embodiment of the present invention with respect to the high PCF of higher MOR/E explanation of the square frame B benefit to further increase strain tolerance.Therefore find, wish according to broad aspect of the present invention, show that the humble cracking main body of the pore size distribution that overall porosity is relatively narrow is favourable.

In addition, according to the embodiment of the present invention, porous ceramic honeycombs also is included in MOR/CFA 〉=1000psi on porous rod, wherein, MOR is room temperature rupture modulus intensity (psi), and CFA is closed forward position area fraction (axle cross section upper wall area (not comprising tamper) is divided by the ceramic honeycomb body total area).In other embodiments, MOR/CFA 〉=1500psi on porous rod, MOR/CFA 〉=2000psi, perhaps MOR/CFA 〉=2500psi even.Figure 14 shows, to 11 μ m≤d ₅₀≤ 15 μ m, humble cracking, porosity are the cordierite honeycomb bodies of the present invention of 54-66%, have and the conventional high crack the same high or higher MOR/CFA intensity of cordierite honeycomb bodies of splitting of only having the 42-51% porosity.

The embodiment of some examples shows and produces the combination with good thermal shocking and feature of the relative high porosity honeycomb structure of the relative low back pressure properties that passes through wall.These embodiments are good candidate of particulate filter applications.Particularly, the cordierite crystal that some embodiments are presented in the wall of honeycomb body structure has preferred crystalline orientation, thereby △ _I〉=0.1, △ wherein _I=I _T-I _A, the CTE≤15x10 between 25-800 ℃ ^-7/ ℃, %P 〉=46%, can be by the connective factor (PCF) in hole〉65% pore size distribution that characterizes, TSP 〉=550 ℃.

Generally speaking, improve these holes without the crack cordierite honeycomb bodies pottery that splits connective (by the PCF that improves, being measured) and help to reduce Young's modulus, improve the strain tolerance of porous material.Can use so the humble cracking trichroite of higher expansion, keep simultaneously many oil engines are polluted the sufficiently high resistance to sudden heating of controlling application.In addition, find to exist intergranular glass to be on good terms further to reduce the crack of ceramic body of the present invention and split, improve intensity and strain tolerance.Figure 15 illustrates the intergranular glassy phase that uses the embodiment of 5% attapulgite soil for the present invention in raw mix.Figure 15 is the scanning electron photomicrograph of polishing section of the honeycomb wall of embodiment of the present invention I29, and this photo shows hole (black), trichroite matrix (grey) and intergranular glassy phase (bright annular region).It is 10 microns at bottom-right scale.

In addition, the embodiment of ceramic body arbitrary orientation of the present invention lacks highly preferred crystalline orientation, shows crack the splitting of reducing, and has good interconnected porosity.Therefore, the microstructure in these embodiment mesexine and matrix is similar.This may help to reduce the physical properties difference, and the physical property qualitative difference may cause stress, produces cosmetic bug such as crackle.The desirable pore morphology of these ceramic honeycomb bodies also may improve filtration efficiency, and is reduced in the pressure drop on the porcelain filter that cleans and load soot.

Other advantages of the ceramic honeycomb body of the humble cracking of this class comprise high mechanical strength, to thin-walled, low hole density and/or the high porosity structure (exhaust back-pressure needed (as wall-flow filter in) of described structure for reducing, the perhaps thermal mass needed (to catalytic ignition faster) for reducing, and/or be that the high catalyst loading capacity is needed) intensity of particularly important.Reduce as far as possible tiny crack or make its relatively upper can also rock steady structure for not existing, the character that prevents structure because of the accumulation that applies non-combustible particulate in catalyst coat and/or waste gas change (or make at least these character to described apply with/accumulate insensitive).There is no thermal shocking to the crack interdependence of splitting, more consistent product can be provided and make in may be still less upset.

Claims (7)

1. porous ceramic honeycombs structure, this structure comprises:

Main cordierite ceramic phase, this shows humble cracking and cordierite crystal orientation mutually, and has the room temperature elastic modulus E _{Room temperature}, room temperature breaking tenacity modulus MOR _{Room temperature}, and high temperature 500-900 ℃ of thermal expansivity CTE _H, make that the thermal shocking parameter TSP of structure is following is calculated as at least 400 ℃:

TSP=MOR _{Room temperature}/ [E _{Room temperature}] [CTE _H], the CTE≤15x10 under 25-800 ° of C ^-7/ ℃,

Described cordierite ceramic has the characteristic of the orientation of cordierite crystal arbitrarily mutually, it is characterized by the value △ that records according to described structure _I=I _T-I _A≤ 0.1, I wherein _TTransversal I ratio, I _AAxial I ratio,

It is characterized in that, described porous ceramic honeycombs has ratio E _Ratio≤ 1.05, E wherein _Ratio=E _H/ E _{Room temperature}, E _H1000 ℃ of Young's modulus under high temperature.

2. porous ceramic honeycombs as claimed in claim 1, is characterized in that, this honeycomb also comprises:

By factor d _f≤ 0.48 and d _b≤ 1.65 porositys that characterize, wherein, d _f=(d ₅₀-d ₁₀)/d ₅₀, d _b=(d ₉₀-d ₁₀)/d ₅₀, d wherein ₁₀, d ₅₀And d ₉₀Be defined as according to standard mercury porosimeter and measure, the difference 10%, 50% of material hole volume and 90% belongs to the more hole of small-bore;

The connective factor PCF in hole 〉=40%, wherein, PCF=% porosity/d _bWith

The differential value of the thermal expansion of tiny crack △ α _mc, △ α _mc≤ 5.0, wherein, △ α _mc=[76.8 (I _A) ³– 129.5 (I _A) ²+ 97.9 (I _A)-12.8]+0.6% (Mu+Sp+Sa+Al)-CTE, wherein % (Mu+Sp+Sa+Al) is the summation of the mullite, spinel, sapphirine and the corundum weight percentage that exist in honeycomb, I _AAxial I ratio as above, the CTE≤15x10 under 25-800 ° of C ^-7/ ℃.

3. porous ceramic honeycombs as claimed in claim 1, is characterized in that, this honeycomb also be included in 25-800 ℃ of mensuration at 12-15x10 ^-7The CTE of/℃ scope.

4. porous ceramic honeycombs as claimed in claim 1, is characterized in that, the E of this honeycomb _Ratio≤ 0.95.

5. porous ceramic honeycombs as claimed in claim 1, is characterized in that, this honeycomb also comprises overall porosity 〉=46%.

6. porous ceramic honeycombs as claimed in claim 1, is characterized in that, this honeycomb also comprises mean pore sizes d ₅₀For the 10-30 micron.

7. porous ceramic honeycombs claimed in claim 1 is configured to the purposes of the device that is selected from lower group: the catalytic converter that is used for the petrol engine exhaust after-treatment, the diesel oxidation catalyst base material, the SCR base material, NOx absorption agent base material, the NOx catalyst substrate, the catalyzed diesel that is used for the diesel engine exhaust aftertreatment, and be used for the non-catalytic diesel particulate filter of diesel engine exhaust aftertreatment.

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