CN110143825B

CN110143825B - Cordierite ceramic honeycomb filter body with narrow pore diameter distribution and preparation method thereof

Info

Publication number: CN110143825B
Application number: CN201910395211.2A
Authority: CN
Inventors: 宋锡滨; 吴艳增; 崔明山; 霍希云; 丁运刚; 张同元
Original assignee: Shandong Sinocera Functional Material Co Ltd
Current assignee: Shandong Sinocera Functional Material Co Ltd
Priority date: 2019-05-13
Filing date: 2019-05-13
Publication date: 2021-11-02
Anticipated expiration: 2039-05-13
Also published as: CN110143825A

Abstract

The application discloses a cordierite ceramic honeycomb filter body with narrow pore size distribution and a preparation method thereof, and belongs to the field of filtering catalytic materials. The cordierite ceramic honeycomb filter body comprises a porous ceramic of cordierite having the following properties: total porosity (% P) of not less than 60%, pore size distribution D_fNot more than 0.45, D₅Not more than 13 μm; wherein the pore size distribution Df ═ D₅₀‑D₁₀)/D₅₀，D₅₀And D₁₀Denotes the aperture value, D₅₀＞D₁₀；D₅₀Represents a pore diameter satisfying the following condition: pore diameter less than D₅₀The pores of (a) account for 50% of the total porosity; d₁₀Represents a pore diameter satisfying the following condition: pore diameter less than D₁₀The pores of (a) account for 10% of the total porosity; d₅Represents a pore diameter satisfying the following condition: pore diameter less than D₅The pores of (a) account for 5% of the total porosity. The cordierite ceramic honeycomb filter body has narrow pore size distribution, small pore occupation ratio, low thermal expansion coefficient and high qualification rate.

Description

Cordierite ceramic honeycomb filter body with narrow pore diameter distribution and preparation method thereof

Technical Field

The application relates to a cordierite ceramic honeycomb filter body with narrow pore size distribution and a preparation method thereof, belonging to the field of filtering catalytic materials.

Background

Particulate filters are used to filter fine Particulate Matter (PM) emitted from gasoline and diesel vehicles. The particulate filter structure is comprised of a honeycomb body and a plugged portion. The cellular walls form a honeycomb body with spaced cells, and the plugging portions form a cross in the form of chess at the inlet and outlet ends of the honeycomb body. The tail gas discharged by the engine passes through the inlet end of the honeycomb filter, fine particles carried by the gas are intercepted by the hole sealing part, and the gas passes through the porous partition wall and enters the adjacent compartments to flow out. The honeycomb particulate filter is classified into a Gasoline Particulate Filter (GPF) and a Diesel Particulate Filter (DPF), and the material of the honeycomb particulate filter matures into a cordierite ceramic honeycomb filter body.

With the strict restriction of PM and PN by the emission regulations, in order to improve the filtration efficiency and reduce the back pressure, the particulate filter is required to have high porosity and narrow pore distribution, but it is difficult to realize narrow pore distribution by adjusting the type and mass percentage of the conventional pore-forming agent, and sintering cracking is easily caused.

Disclosure of Invention

In order to solve the above problems, the present application provides a method for efficiently controlling the sintering step of a green cordierite ceramic honeycomb filter body to produce a cordierite ceramic honeycomb filter body having a narrow pore size distribution, a small pore fraction, a low coefficient of thermal expansion, and a high yield.

According to one aspect of the present application, there is provided a cordierite ceramic honeycomb filter body comprising a porous ceramic of cordierite having the following properties: total porosity (% P) of not less than 60%, pore size distribution D_fNot more than 0.45, D₅Not less than 8 μm;

wherein the pore size distribution Df ═ D₅₀-D₁₀)/D₅₀，D₅₀And D₁₀Denotes the aperture value, D₅₀＞D₁₀；D₅₀Represents a pore diameter satisfying the following condition: pore diameter less than D₅₀The pores of (a) account for 50% of the total porosity; d₁₀Represents a pore diameter satisfying the following condition: pore diameter less than D₁₀The pores of (a) account for 10% of the total porosity;

D₅represents a pore diameter satisfying the following condition: pore diameter less than D₅The pores of (a) account for 5% of the total porosity.

Optionally, the total porosity (% P) is 60% to 65%, pore size distribution D_fNot more than 0.43, D₅Not less than 9 μm.

Preferably, the pore size distribution D_fNot greater than 0.41. Further, the pore size distribution Df is less than 0.4. Further, the pore size distribution Df is less than 0.39。

Optionally, the D₅Not less than 10 μm. Preferably, said D₅Not less than 11 μm.

Optionally, the cordierite ceramic honeycomb filter has a coefficient of thermal expansion CTE ≦ 7.5 × 10 in the range of 25-800 deg.C^-7and/K. Preferably, the cordierite ceramic honeycomb filter has a coefficient of thermal expansion CTE ≦ 7 × 10 in the range of 25-800 deg.C^-7and/K. Further, the cordierite ceramic honeycomb filter body has a coefficient of thermal expansion CTE ≤ 6.5 × 10 at 25-800 deg.C^-7and/K. Further, the cordierite ceramic honeycomb filter has a coefficient of thermal expansion CTE ≦ 6 × 10 in the range of 25-800 deg.C^-7/K。

Optionally, the cordierite ceramic honeycomb filter has an average pore size of 20.5 to 24 μm. Preferably, the cordierite ceramic honeycomb filter has an average pore size of 21 to 23 μm.

According to another aspect of the present application, there is provided a method of making a cordierite ceramic honeycomb filter according to any of the preceding claims, comprising the steps of: sintering the provided cordierite ceramic honeycomb filter body green body to obtain the cordierite ceramic honeycomb filter body;

wherein, the sintering step comprises:

1) a first temperature rise stage: heating the green body to a first temperature according to a first heating rate, wherein the first heating rate is 70-125 ℃/h, and the first temperature is 140-160 ℃;

2) a second temperature rising stage: heating the green body from a second temperature to a second temperature according to a second heating rate, wherein the second heating rate is less than the first heating rate, and the second temperature is 230-280 ℃;

3) a third temperature rise stage: heating the green body from the second temperature to a third temperature according to a third heating rate, wherein the third heating rate is less than or equal to the first heating rate, and the third temperature is 1200-1300 ℃;

4) a fourth temperature rise stage: heating the green body from a fourth temperature to a heat preservation temperature according to a fourth heating rate, wherein the fourth heating rate is less than or equal to the first heating rate, and the heat preservation temperature is greater than the fourth temperature; and

5) keeping the green body in the heat preservation stage for a period of time, and then cooling to obtain the cordierite ceramic honeycomb filter body;

the cordierite ceramic honeycomb filter body is 200mm or less in diameter, and the height-diameter ratio is 1:3-3: 1.

Optionally, the first temperature-raising rate is 100-. Preferably, the first ramp rate is 120 ℃/h.

Optionally, the second ramp rate is 10-30 ℃/h. Optionally, the second ramp rate is 15-25 ℃/h.

Preferably, the lower limit of the first temperature is selected from 142 ℃, 144 ℃, 146 ℃, 148 ℃ or 150 ℃, and the upper limit is selected from 150 ℃, 152 ℃, 154 ℃, 156 ℃ or 158 ℃.

Preferably, the second temperature has a lower limit selected from 235 ℃, 240 ℃, 245 ℃ or 250 ℃ and an upper limit selected from 250 ℃, 255 ℃, 260 ℃, 265 ℃, 270 ℃ or 275 ℃.

Preferably, the first temperature is 150 ℃, the second temperature is 250 ℃, and the second heating rate is 20 ℃/h.

Optionally, the fourth temperature rise rate is 20-40 ℃/h. Preferably, the lower limit of the fourth temperature rise rate is selected from 22 ℃/h, 24 ℃/h, 26 ℃/h, 28 ℃/h or 30 ℃/h, and the upper limit is selected from 32 ℃/h, 34 ℃/h, 36 ℃/h or 38 ℃/h. More preferably, the fourth ramp rate is 30 ℃/h.

Optionally, the third warming phase includes:

a first temperature rise stage: heating the green body from the second temperature to the A temperature according to the A heating rate, wherein the A heating rate is less than or equal to the first heating rate, and the A temperature is 450-500 ℃;

a temperature rise stage B: heating the green body from the A temperature to the B temperature according to the B temperature rise rate, wherein the B temperature rise rate is less than the first temperature rise rate, and the B temperature is 580-640 ℃; and

c, temperature rising stage: and heating the green body from the B temperature to a third temperature according to a C heating rate, wherein the C heating rate is less than or equal to the first heating rate, and the third temperature is 1200-1300 ℃.

Optionally, the temperature rise rate of the B th heating pipe is 5-15 ℃/h. Preferably, the lower limit of the temperature rise rate B is selected from 6 ℃/h, 7 ℃/h, 8 ℃/h, 9 ℃/h or 10 ℃/h, and the upper limit is selected from 11 ℃/h, 12 ℃/h, 13 ℃/h or 14 ℃/h. More preferably, the B th heating rate is 10 ℃/h.

Optionally, the A temperature rise rate is 80-120 ℃/h. Preferably, the lower limit of the A temperature rise rate is selected from 85 ℃/h, 90 ℃/h, 95 ℃/h, 100 ℃/h or 105 ℃/h, and the upper limit is selected from 100 ℃/h, 105 ℃/h, 110 ℃/h or 115 ℃/h.

Optionally, the C heating rate is 70-90 ℃/h. Preferably, the lower limit of the Cth heating rate is selected from 72 ℃/h, 74 ℃/h, 76 ℃/h, 78 ℃/h or 80 ℃/h, and the upper limit is selected from 82 ℃/h, 84 ℃/h, 86 ℃/h or 88 ℃/h.

Preferably, the third temperature is 1300 ℃.

Optionally, the heat preservation temperature is 1415-.

Preferably, the temperature is 1421-.

Preferably, the holding time is 6h-20 h. Further, the heat preservation time is 12-18 h. Further, the incubation time was 15 h.

In the prior art, the influence of a sintering temperature rise program on the pore size distribution of the filter body is not concerned, particularly the influence of the second temperature rise stage and the A-th temperature rise stage on the pore size distribution of the filter body is not concerned. The inventors have surprisingly found that the combination of the conditions of the second temperature rise stage and the a temperature rise stage described in the present application allows the production of a filter with a narrow pore size distribution and a low proportion of small pores, and reduces the number of cracks in the filter. The condition control of the temperature raising stage B can prepare a filter body with less cracks and no cracking. The condition control of the first temperature rise stage can improve the sintering efficiency and can not reduce the quality of the prepared filter body. The condition control of the heat preservation stage in the step 5) can ensure that the crystal form of the crystal of the filter body is more complete, and the prepared filter body has low thermal expansion coefficient, namely strong thermal shock resistance.

Preferably, the preparation method of the cordierite ceramic honeycomb filter body comprises the following steps: mixing the raw material composition, a pore-forming agent, a binder and a lubricant to form a ceramic primary mixture, forming a honeycomb biscuit body from the plasticized ceramic primary mixture, and roasting the honeycomb biscuit body to obtain a cordierite ceramic honeycomb filter body;

the raw material composition comprises the following components in parts by weight: 38-42 talc, 13-19 kaolin, 12-18 alumina, 12-18 aluminum hydroxide and 5-15 silica;

the average particle size of talc is 15-20 μm, the average particle size of kaolin is 4-7 μm, the average particle size of alumina is 3-5 μm, the average particle size of aluminum hydroxide is 5-8 μm, and the average particle size of silica is 3-5 μm; and

the weight ratio of the raw material composition, the binder, the pore-forming agent and the lubricant is 1: 0.04-0.08: 0.07-0.15: 0.015-0.025.

Optionally, the raw material composition comprises the following components in parts by weight: 40 talc, 16.8 kaolin, 15.2 alumina, 15.8 aluminum hydroxide and 12.2 silica; talc average particle size 20 μm, kaolin average particle size 7 μm, alumina average particle size 5 μm, aluminum hydroxide average particle size 5 μm, and silica average particle size 5 μm; and the weight ratio of the raw material composition, the binder, the pore-forming agent and the lubricant is 1: 0.06: 0.1: 0.02.

preferably, the method for manufacturing the cordierite ceramic honeycomb filter body comprises the following steps:

1) providing a cordierite-forming feedstock composition;

2) the raw material composition, the pore-forming agent, the binder, the lubricant and water are wet-mixed to form a ceramic primary mixture, and the ceramic primary mixture is subjected to pugging, extrusion molding, microwave drying, pore plugging and sintering to obtain the cordierite ceramic honeycomb.

Optionally, the pore former is selected from at least one of starch, resin, expanded microspheres, and plastic beads. The plastic pellet includes organic polymer particles having an average particle diameter of 20 to 60 μm.

Optionally, the organic polymer particles are selected from at least one of polyphenylene sulfide, polyvinyl alcohol, and polymethyl methacrylate. Preferably, the organic polymer particles are polyphenylene sulfide.

Optionally, the organic polymer particles are uniformly solid spherical.

Optionally, the organic polymer particles have an average particle size of 30-50 μm. Preferably, the organic polymer particles have an average particle diameter of 35 to 45 μm. More preferably, the organic polymer particles have an average particle diameter of 40 to 50 μm. Most preferably, the organic polymer particles have an average particle size of 45 μm.

Optionally, the binder is selected from methylcellulose and/or hydroxypropyl methylcellulose and; the lubricant is selected from at least one of tall oil fatty acid, salad oil and rapeseed oil.

Preferably, the binder is hydroxypropyl methylcellulose and the lubricant is tall oil fatty acid.

Herein, the cordierite ceramic honeycomb filter body comprises a material or a shaped product made of the material, such as a plugged or unplugged wall-flow honeycomb filter, such as a GPF or DPF, or the like.

Benefits of the present application include, but are not limited to:

1. according to the cordierite ceramic honeycomb filter body, the pore distribution is narrow, the proportion of small pores is small, the sintering is not cracked, and the improvement of the filtering efficiency and the reduction of the back pressure of the filter body are facilitated.

2. The cordierite ceramic honeycomb filter body has an excellent thermal expansion coefficient, namely, high thermal shock resistance in the use process.

3. According to the preparation method of the cordierite ceramic honeycomb filter body, the sintering time is short, the sintering efficiency is high, the quality of the prepared filter body is high, the generated cracks are few, and the qualification rate is high.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

fig. 1 is a scanning electron microscope image of a filter 18# according to an embodiment of the present application.

FIG. 2 is a scanning electron micrograph of a comparative filter D12# according to an example of the present application.

FIG. 3 is a SEM image of a comparative filter D15# according to the example of the present application.

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

Unless otherwise specified, the raw materials and catalysts in the examples of the present application were commercially available, wherein the polyphenylene sulfide had a purity of 99%, the polyvinyl alcohol had a purity of 99%, and the polymethyl methacrylate had a purity of 99%.

The analysis method in the examples of the present application is as follows:

the mercury intrusion instrument of model AutoPore IV 95XX of Mimmerrieke instruments ltd is used for carrying out porosity, average pore diameter, pore distribution diagram and pore distribution index D_fTest (D)_f＝(D₅₀-D₁₀)/D₅₀The smaller the value, the more concentrated the pore distribution). The test method comprises the following steps: the evaluation object was cut into a rectangular parallelepiped of 11X 18.5mm, and the evaluation object was placed in a mercury porosimeter for testing.

The evaluation method for whether sintering cracks comprises the following steps: and (3) placing the cordierite ceramic honeycomb filter body before sintering in a shuttle kiln for sintering, and judging whether the sintering is cracked or not by using a light leakage detector after sintering.

Evaluation of thermal expansion coefficient: the Coefficient of Thermal Expansion (CTE) was measured using a thermal expansion tester DIL402 from Chi-chi Germany, with a sample size of 5mm by 50mm, at a temperature ranging from room temperature to 800 ℃ and a rate of temperature rise of 5 ℃/min. The CTE is calculated as: α ═ Δ L/(L × Δ T), where α is the coefficient of thermal expansion, Δ L is the length of sample expansion, L is the sample length, and Δ T is the test temperature difference.

The thermal shock resistance test was performed using a muffle furnace. Putting the filter body to be evaluated into a resistance furnace which reaches a specified temperature, keeping the temperature for 30min, taking out the gasoline particle filter from the resistance furnace, and observing whether the skin and the end face are cracked or not at the first time. If no cracking is observed, the mixture is cooled to room temperature (25 ℃) and then charged into an electric furnace. The above procedure was repeated three times and if cracking was found, the test was stopped. If no cracking is found, the resistance furnace is heated to 50 ℃, and the process is repeated three times. The temperature at which cracking occurred was used as a criterion for evaluation.

According to one embodiment of the present application, a method of sintering a cordierite ceramic honeycomb filter body comprises the steps of:

1) mixing: the prepared raw material composition, the pore-forming agent and the binder are dry-mixed in a mixer, and then mixed liquid of the lubricant and water is sprayed in for wet mixing;

2) pugging: conveying the wet-mixed ceramic primary mixture to a mesh pugging machine for pugging;

3) and (3) extrusion molding: pugging is conveying pug to a single-screw extruder, a double-screw extruder or a hydraulic extruder for molding, and the pug becomes a cylindrical wet blank through a die;

4) microwave drying: cutting by a wet blank cutting machine, drying and shaping the honeycomb ceramic cylinder by a microwave dryer to form a biscuit;

5) cutting the biscuit: cutting the biscuit into a specific height by a biscuit cutting machine;

6) hole plugging: laminating the end face of the cut biscuit, and alternately plugging holes by a plugging machine after punching by a laser drilling machine;

7) and (3) sintering: and sintering the biscuit after the hole is blocked by a shuttle kiln or a tunnel kiln.

Example 1 preparation of cordierite ceramic honeycomb Filter No. 1

Raw material composition # 1 which can be fired into cordierite ceramic honeycomb filter: 40 wt% of talc having an average particle size of 20 μm, 16.8 wt% of kaolin having an average particle size of 7 μm, 15.2 wt% of alumina having an average particle size of 5 μm, 15.8 wt% of aluminum hydroxide having an average particle size of 5 μm, and 12.2 wt% of silica having an average particle size of 5 μm.

Preparation of cordierite ceramic honeycomb filter body # 1: 100Kg of raw material composition 1#, 6Kg of hydroxypropyl methyl cellulose, 10Kg of walnut powder, 2Kg of tall oil fatty acid and 33Kg of water are mixed in a mixer, and the ceramic primary mixture after mixing is kneaded or pugged to prepare pug. And (3) conveying the pug to a double-screw extruder or a hydraulic extruder for molding, wherein the pug is formed into a cylindrical wet blank through a die. And after the wet blank cutting operation, drying and shaping the honeycomb ceramic cylinder into a biscuit by using a microwave dryer. Cutting the biscuit into a specific height by a cutter, and sintering according to a sintering method of Q1 to obtain the cordierite ceramic honeycomb filter body No. 1.

The cordierite ceramic honeycomb filter body 1# has a diameter of 200mm or less and a length-to-diameter ratio of 1:3 to 3: 1.

Example 2 preparation of cordierite ceramic honeycomb filters No. 2-7 # and comparative cordierite ceramic honeycomb filters No. D1-D8 #

Cordierite ceramic honeycomb filter 2# -7# and comparative cordierite ceramic honeycomb filter D1# -D8# were prepared according to the preparation method of cordierite ceramic honeycomb filter 1# of example 1, which was different from the preparation method of cordierite ceramic honeycomb filter 1# in the sintering method, cordierite ceramic honeycomb filter 2# -5# was sintered by Q2, Q3, Q4, Q5, Q6 and Q7, comparative cordierite ceramic honeycomb filter D1# -D8# was sintered by QD1, QD2, QD3, QD4, QD5, QD6, QD7 and QD8, respectively, and comparative cordierite ceramic honeycomb filter D2-Q7, QD1-QD8 were prepared as shown in table 1.

TABLE 1

Example 3 performance testing of cordierite ceramic honeycomb filters No. 2-7 # and comparative cordierite ceramic honeycomb filters No. D1-D8 #

Comprehensively evaluating whether pores and sintering of the prepared cordierite ceramic honeycomb filter body No. 1-7 and a comparative cordierite ceramic honeycomb filter body D1-D8 are cracked, wherein the porosity is more than or equal to 60 percent and less than or equal to 65 percent, the average pore diameter is more than or equal to 20 mu m and less than or equal to 24 mu m, the Df is less than or equal to 0.45, the D5 is more than or equal to 7 mu m, the cordierite ceramic honeycomb filter body which is not cracked in sintering is evaluated as qualified, and the cordierite ceramic honeycomb filter body which is not cracked in sintering is regarded as unqualified when the cordierite ceramic honeycomb filter body does not meet one of the two evaluation standards, wherein D is regarded as unqualified₅The evaluation results are shown in Table 2, corresponding to a pore diameter corresponding to 5% of the total volume。

TABLE 2

The porous honeycomb structures of examples 1 to 7 were comprehensively evaluated as "acceptable" in terms of the cell characteristics and whether cracking occurred during sintering. The porous honeycomb structures of filters 1 and 2 were compared with each other by using QD1 and QD2 sintering curves, respectively, and the sintering was cracked although the pore characteristics satisfied the requirements, and therefore, the comprehensive evaluation was not satisfactory. The porous honeycomb structures of the comparative filters D2# -D8# were respectively selected from the QD2-QD8 sintering curves, and although the sintering did not crack, the pore characteristics did not meet the requirements, so the comprehensive evaluation was not qualified. In the embodiment, the first temperature, the second heating rate, the A temperature and the A heating rate of the second heating stage can prepare a filter body with narrow pore distribution and small pore ratio. In the example, the temperature increase rate at the B-th temperature increase stage and the B-th temperature increase stage produced a filter with few cracks and no cracks. The temperature rise rate of the first temperature rise stage in the embodiment can improve the sintering efficiency without reducing the quality of the prepared filter body.

Example 4 preparation and Performance testing of cordierite ceramic Honeycomb Filter No. 8-18 and comparative cordierite ceramic Honeycomb Filter No. D9-D15

Cordierite ceramic honeycomb filter 8# -18# and comparative cordierite ceramic honeycomb filter D9# -D15# were prepared according to the method of preparation of cordierite ceramic honeycomb filter 1# of example 1, which was different from the method of preparation of cordierite ceramic honeycomb filter 1# in the sintering method; the sintering method is divided into four sections: a coke discharging section (room temperature-400 ℃), a temperature rising section (400-heat preservation temperature), a heat preservation section (highest temperature heat preservation) and a temperature reduction section (heat preservation temperature-100 ℃). The sintering method of cordierite ceramic honeycomb filter 8# -7# and comparative cordierite ceramic honeycomb filter D9# -D8# comprises four stages: a coke discharging section (room temperature-400 ℃), a heating section (400-heat preservation temperature), a heat preservation section (highest temperature heat preservation) and a cooling section (heat preservation temperature-100 ℃); wherein the glue discharging section adopts a speed of 10 ℃/min, the temperature rising section adopts a speed of 40 ℃/min, and the temperature falling section adopts 100 ℃/The rate of min. The incubation temperature, time and evaluation results are shown in Table 3. The thermal expansion coefficient of the cordierite ceramic honeycomb filter body is less than 0.75 x 10^-6and/K, the thermal shock resistance is rated as qualified when the temperature is higher than 650 ℃, and is not rated as unqualified when the temperature is not higher than 650 ℃.

TABLE 3

As shown in Table 3, the thermal expansion coefficient of the filter body obtained at the holding temperature and holding time in the holding stage in the examples was low, i.e., the filter body had high thermal shock resistance. The crystal forms of the crystals of the filters obtained at the holding temperature and holding time in the holding stage in the examples are more complete and are illustrated by scanning electron microscopy according to filter # 18, comparative filter # D12 and comparative filter # D15, respectively, fig. 1, fig. 2 and fig. 3. With the increase of the sintering temperature, cordierite particles gradually become coarse from thin to long, crystal grains are produced more and more fully, defects are fewer and fewer, and the CTE is favorably reduced, and the thermal shock resistance is improved. When the firing temperature exceeds 1430 ℃, crystal grains are in a molten state, and according to a cordierite phase diagram, the crystal phase is changed, the directional arrangement is deteriorated, the CTE is reduced, and the thermal shock resistance is deteriorated.

Example 5 preparation and Performance testing of cordierite ceramic Honeycomb Filter No. 19-26 # and comparative cordierite ceramic Honeycomb Filter No. D16-D24 #

Cordierite ceramic honeycomb filter 19# -26# and comparative cordierite ceramic honeycomb filter D16# -D24# were prepared according to the method of preparing cordierite ceramic honeycomb filter 1# of example 1, which differs from the method of preparing cordierite ceramic honeycomb filter 1 #: sintering conditions are as follows: the temperature rise rate of 30-480 ℃ is 40-200 ℃/h, the temperature rise rate of 480-600 ℃ is 20 ℃/h, the temperature rise rate of 600-1420 ℃ is 60-175 ℃/h, and 1420 ℃ is kept for 5.5-6.5 h; ② the raw material composition 1# of the cordierite honeycomb ceramic can be prepared by sintering: 40 wt% of talc having an average particle size of 16 to 19 μm, 10.8 wt% of kaolin having an average particle size of 6 to 7 μm, 6 wt% of calcined kaolin having an average particle size of 2 to 3 μm, 15.2 wt% of alumina having an average particle size of 3 to 4 μm, 15.8 wt% of aluminum hydroxide having an average particle size of 5 to 8 μm, and 12.2 wt% of silica having an average particle size of 3 to 5 μm; and table 4.

Comprehensively evaluating the pore parameters and sintering cracking of the prepared cordierite ceramic honeycomb filter 19# -26# and the comparative cordierite ceramic honeycomb filter D16# -D24#, wherein the porosity is more than or equal to 60% and less than or equal to 65%, the average pore diameter is more than or equal to 20 mu m and less than or equal to 24 mu m, the Df is less than or equal to 0.45, the D5 is more than or equal to 7 mu m, the cordierite ceramic honeycomb filter which is not cracked in sintering is evaluated as qualified, and the cordierite ceramic honeycomb filter which is not cracked in sintering is regarded as unqualified, wherein D is not qualified when one of the two evaluation standards is not met₅The evaluation results are shown in Table 4, corresponding to a pore diameter corresponding to 5% of the total volume.

TABLE 4

The purity of the walnut powder, the pea powder and the potato powder is more than 95 percent, the foaming microspheres are micro spherical plastic particles and consist of a polymer shell and gas wrapped by the polymer shell, and the polymer shell is made of polyvinyl chloride balls or polymethyl methacrylate balls.

As can be seen from table 4, the cordierite ceramic honeycomb filter 19# prepared by mixing the raw material components with polyphenylene sulfide having a spherical average particle size of 45 μm as a pore-forming agent has the maximum porosity, a narrow pore size distribution, a low small pore size content, and is not easily cracked by sintering, and the evaluation result is acceptable. The cordierite ceramic honeycomb filter body 22# -24# prepared by respectively taking square polyphenylene sulfide, spherical polyvinyl alcohol and spherical polymethyl methacrylate as pore-forming agents has the porosity, narrow pore size distribution and lower performance of small pore size content than that of the cordierite ceramic honeycomb filter body 1#, but the evaluation result is qualified. And from cordieriteThe ceramic honeycomb filter body 19# -22# and the cordierite ceramic honeycomb filter body 25# -26# can show that the average grain diameter and the addition amount of the pore-forming agent have great influence on the prepared filter body, and the cordierite ceramic honeycomb filter body which has the advantages of maximum porosity, narrow pore size distribution, low small pore size content and difficult cracking after sintering is prepared by a great amount of exploration through the sintering method of the application. The test result of comparing the cordierite ceramic honeycomb filter body D16# -D24# is unqualified, and the porosity, the average pore diameter and D are increased along with the increase of the mass percentage of the walnut powder₅Increased, but increased risk of sintering cracking, and porosity, mean pore diameter, D₅Lower, D_fLarger, thus resulting in a comprehensive evaluation as disqualified. The comparative cordierite ceramic honeycomb filter body D16# -D24# prepared by adding no pore-forming agent or walnut powder, pea powder, potato powder foaming microspheres and graphite foaming microspheres in the preparation process can not meet the requirements of the application.

The above description is only an example of the present application, and the protection scope of the present application is not limited by these specific examples, but is defined by the claims of the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the technical idea and principle of the present application should be included in the protection scope of the present application.

Claims

1. A cordierite ceramic honeycomb filter body comprising a porous ceramic of cordierite having the following properties: total porosity% P of not less than 60%, pore size distribution D_fNot more than 0.45, D₅Not less than 8 μm;

wherein the pore size distribution D_f＝(D₅₀-D₁₀)/D₅₀，D₅₀And D₁₀Denotes the aperture value, D₅₀＞D₁₀；D₅₀Represents a pore diameter satisfying the following condition: pore diameter less than D₅₀The pores of (a) account for 50% of the total porosity; d₁₀Represents a pore diameter satisfying the following condition: pore diameter less than D₁₀The pores of (a) account for 10% of the total porosity;

D₅represents a pore diameter satisfying the following condition: pore diameter less than D₅The pores of (a) account for 5% of the total porosity;

the cordierite ceramic honeycomb filter body has a coefficient of thermal expansion CTE < 7 x 10 in the range of 25-800 DEG C^-7/K；

The cordierite ceramic honeycomb filter body is prepared by a method comprising the following steps: sintering the provided cordierite ceramic honeycomb filter body green body to obtain the cordierite ceramic honeycomb filter body;

wherein, the sintering step comprises:

2) a second temperature rising stage: heating the green body from the first temperature to a second temperature according to a second heating rate, wherein the second heating rate is less than the first heating rate, the second temperature is 230 ℃ and 280 ℃, and the second heating rate is 10-30 ℃/h;

4) a fourth temperature rise stage: heating the green body from the third temperature to a heat preservation temperature according to a fourth heating rate, wherein the fourth heating rate is less than or equal to the first heating rate, the heat preservation temperature is greater than the third temperature, the heat preservation temperature is 1415-; and

5) and (3) a heat preservation stage: keeping the green body in the heat preservation stage for a period of time, and then cooling to obtain the cordierite ceramic honeycomb filter body;

wherein the diameter of the cordierite ceramic honeycomb filter body is less than 200mm, and the length-to-diameter ratio is 1:3-3: 1;

the green honeycomb filter body is made by a method comprising the steps of: mixing a raw material composition, a pore-forming agent, a binder and a lubricant to form a ceramic primary mixture, and plasticizing the ceramic primary mixture to obtain the ceramic primary mixture, wherein the pore-forming agent is selected from at least one of resin, foamed microspheres and plastic beads;

the third warming phase includes:

a first temperature rise stage: heating the green body from the second temperature to the A temperature according to the A temperature rise rate, wherein the A temperature rise rate is less than or equal to the first temperature rise rate, the A temperature is 450-500 ℃, and the A temperature rise rate is 80-120 ℃/h;

a temperature rise stage B: and heating the green body from the A temperature to the B temperature according to the B temperature rise rate, wherein the B temperature rise rate is less than the first temperature rise rate, the B temperature is 580-640 ℃, and the B temperature rise rate is 5-15 ℃/h.

2. The cordierite ceramic honeycomb filter of claim 1 wherein the total porosity (% P) is from 60% to 65% and the pore size distribution D_fNot more than 0.43, said D₅Not less than 9 μm.

3. A method of making a cordierite ceramic honeycomb filter according to claim 1 or claim 2, comprising the steps of: sintering the provided cordierite ceramic honeycomb filter body green body to obtain the cordierite ceramic honeycomb filter body;

wherein, the sintering step comprises:

the third warming phase includes:

4. The method of making a cordierite ceramic honeycomb filter according to claim 3 wherein the first temperature is 150 ℃, the second temperature is 250 ℃, and the second ramp rate is 20 ℃/h.

5. The method of making a cordierite ceramic honeycomb filter according to claim 3 wherein the fourth ramp rate is from 20 to 40 ℃/h.

6. The method of making a cordierite ceramic honeycomb filter according to claim 5, wherein the fourth ramp rate is 30 ℃/h.

7. The method of making a cordierite ceramic honeycomb filter according to claim 3, wherein the third ramp-up stage further comprises:

8. The method of making a cordierite ceramic honeycomb filter of claim 7 wherein the Bth ramp rate is 10 ℃/h.

9. The method of making a cordierite ceramic honeycomb filter according to claim 3 wherein the soak time is from 6 to 20 hours.

10. The method of making a cordierite ceramic honeycomb filter according to any one of claims 3-8, wherein the feedstock composition comprises the following components in parts by weight: 38-42 talc, 13-19 kaolin, 12-18 alumina, 12-18 aluminum hydroxide and 5-15 silica;