Low-expansion cordierite ceramic prepared using chlorite and preparation method thereof
By using chlorite and fused quartz to prepare low-expansion cordierite ceramics, the purity and expansion coefficient problems caused by high talc content are solved, efficient and low-cost cordierite ceramic production is achieved, and the product's thermal shock resistance and service life are improved.
Patent Information
- Application Number
- CN202510757717.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-09
- Publication Date
- 2025-09-12
- Estimated Expiration
- 2045-06-09
AI Technical Summary
In the existing technology, the raw materials used for artificial synthesis of cordierite have a high talc content, resulting in low cordierite purity, large expansion coefficient, poor thermal shock resistance of the product, short service life, and secondary pollution caused by the flotation process and increased costs.
Low-expansion cordierite ceramics are prepared using chlorite as raw material, combined with kaolin and alumina through ball milling, wet ball milling, calcination, crushing and other steps. Fused quartz is added to reduce the expansion coefficient and improve the purity and flexural strength.
Prepare cordierite ceramic materials with high crystallinity and low expansion coefficient, reduce production costs, improve flexural strength and thermal expansion performance, meet the production needs of enterprises, and be environmentally friendly and efficient.
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Figure CN120247541B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of ceramics, and in particular to a low-expansion cordierite ceramic prepared by utilizing chlorite and a preparation method thereof. Background Art
[0002] As a group-like silicate mineral, cordierite has a hexagonal crystal structure, and its structural unit is a six-membered ring composed of [SiO4] tetrahedron and [AlO4] tetrahedron. The unit is arranged in an orderly manner along the c-axis, and the silicon-oxygen tetrahedron and the aluminum-oxygen tetrahedron are connected by common edges. Therefore, it has a series of excellent properties such as excellent thermal expansion performance, thermal shock resistance, and chemical stability, which can meet a variety of needs. Cordierite can be found in thermal furnaces, electronic devices, low-expansion ceramics, kiln tools, and photolithography machines. However, the yield of natural cordierite is very low, and its performance is poor and cannot be used. Therefore, cordierite needs to be artificially synthesized, among which the solid-phase synthesis method is the most commonly used method in industrial production. At present, the synthesis of cordierite mostly adopts the talc-kaolin-alumina system and the kaolinite-magnesite-talc system. However, the talc system often results in a high CaO content in the system, generally between 3% and 8%, because talc is accompanied by dolomite or calcite. This makes the purity of the synthesized cordierite low, and the synthesis amount of cordierite is unstable, resulting in a large expansion coefficient of cordierite, generally around 2.8×10 -6 / ℃-3.5×10 -6 The temperature fluctuates between 100°C and 200°C. Honeycomb ceramics, kiln tools, and heat-resistant ceramics made from this cordierite have poor thermal shock resistance and are prone to cracking, resulting in a short service life and increased replacement costs. With the upgrading of equipment and the increasing requirements of usage scenarios, the requirements for the performance of cordierite powder are also becoming increasingly stringent. Some companies are also using talc flotation to increase the purity of cordierite synthesis and reduce the expansion coefficient of synthetic cordierite. However, this process causes secondary pollution and increases costs. Summary of the Invention
[0003] The purpose of the present invention is to overcome the problem of high talc content in the artificially synthesized cordierite raw materials in the prior art, and to provide a low-expansion cordierite ceramic prepared from chlorite and a preparation method thereof.
[0004] The present invention is achieved through the following technical solution: a low-expansion cordierite ceramic prepared using chlorite, characterized in that the chemical composition of the low-expansion cordierite ceramic is as follows, calculated by mass percentage: SiO2 47.3-48.8%, Al2O3 37.6-39.1%, CaO 0.5-0.6%, MgO 12.35-13.4%, Fe2O3 0.05-0.1%, K2O 0.01-0.02%, Na2O 0.003-0.009%, and TiO2 0.16-0.21%.
[0005] The method for preparing the low-expansion cordierite ceramic is characterized by comprising the following steps:
[0006] Step 1: Using chlorite as raw material, after ball milling and screening, adding a certain amount of kaolin and alumina and mixing evenly, and then wet ball milling, calcining, and crushing to obtain a cordierite precursor;
[0007] Step 2: adding a certain amount of fused quartz to the cordierite precursor obtained in step 1, placing the ball-milled slurry in an oven for drying to obtain a mixed powder;
[0008] Step 3: The mixed powder obtained in step 2 is granulated, aged, dry-pressed and fired to obtain low-expansion cordierite ceramics.
[0009] The chemical composition of the chlorite in the step 1 is as follows in mass percentage: SiO2 32.45-33.72%, Al2O3 15.86-16.06%, Fe2O3 0.5-0.6%, TiO2 0.54-0.64%, CaO 0.05-0.07%, MgO 35.54-35.64%, K2O 0.04-0.06%, Na2O 0.01-0.02%, and loss on ignition 13.6-14.6%.
[0010] In the step 1, the chlorite is ball-milled for 30 minutes and then passed through an 80-120 mesh sieve, the fineness of the kaolin is passed through a 40-80 mesh sieve, the fineness of the alumina is passed through a 120-160 mesh sieve, and the weight ratio of chlorite:kaolin:alumina is 29.8-32.4:44.6-64.7:2.9-12.9.
[0011] The wet ball milling process in step 1 is carried out for 20 to 30 minutes, the calcination process is carried out at a temperature of 800 to 900° C. and the holding time is 1 to 2 hours, and the fineness of the pulverization process is such that the product passes through a 250-mesh sieve.
[0012] In the step 2, the weight ratio of cordierite precursor to fused quartz is 29.8-32.4:0.5-10.
[0013] In the ball milling process of step 2, the weight ratio of material: water: ball mill is 1:4-5:1.5-2.5, the ball milling time is 20-40 minutes, the fineness is passed through an 80-100 mesh sieve, the temperature of the drying process is 80° C., and the drying time is 12 hours.
[0014] The particle size of the granulation process in step 3 is passed through an 80-100 mesh sieve, the time of the aging process is 2-4 hours, the pressure of the dry pressing process is 5-10 MPa, and the pressure holding time is 30-40 seconds.
[0015] The firing system of the firing process in step three is as follows: the heating rate from 50 to 600°C is 2.5 to 3.5°C / min, the heating rate from 600 to 1000°C is 4 to 5°C / min, the heating rate from 1000°C to the maximum firing temperature is 2 to 3°C / min, the holding time at the maximum firing temperature is 2 to 4 hours, and then the temperature is lowered with the furnace, and the maximum firing temperature is 1300 to 1360°C.
[0016] The low expansion cordierite ceramics obtained in step 3 have a crystallinity of 88.5-93.8%, a flexural strength of 40.12-43.38 MPa, and a thermal expansion coefficient of 1.86-2.53×10 -6 / ℃, water absorption rate is 2.23~2.96%, and bulk density is 2.185~2.445g / cm 3 .
[0017] The present invention has the following beneficial effects:
[0018] (1) The chlorite used in the present invention has a high purity component and a low content of elements with high expansion coefficients (Ca, K, Na), and can be used to synthesize cordierite ceramic materials with high crystallinity and low expansion coefficient.
[0019] (2) The present invention adds fused quartz with a low expansion coefficient, which can produce a low-expansion glass liquid phase at high temperature, promote the synthesis of cordierite crystals, and reduce the water absorption rate of cordierite ceramics, making the structure denser and improving the flexural strength of the ceramics.
[0020] (3) The application method of the present invention has simple process, low production cost, high production efficiency, low production energy consumption, economy and environmental protection, and has effectively overcome the problem of high talc content in existing cordierite preparation raw materials, and can well meet the actual production and application needs of enterprises, and promote the application and development of related industries. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 The particle size distribution and cumulative particle size test results of the low expansion cordierite ceramic prepared in Example 5 are as follows;
[0022] Figure 2 These are the XRD test results of the low-expansion cordierite ceramics prepared in Examples 1-5;
[0023] Figure 3 This is the SEM test result of the low-expansion cordierite ceramic prepared in Example 5. DETAILED DESCRIPTION
[0024] In order to further illustrate the present invention and the technical means and effects adopted to achieve the predetermined purpose of the invention, the present invention is described in detail below in conjunction with preferred embodiments.
[0025] Example 1
[0026] A method for preparing low-expansion cordierite ceramics using chlorite comprises the following steps:
[0027] Step 1: Using chlorite as raw material, after ball milling and screening, adding a certain amount of kaolin and alumina and mixing evenly, and then wet ball milling, calcining, and crushing to obtain a cordierite precursor;
[0028] Step 2: adding a certain amount of fused quartz to the cordierite precursor obtained in step 1, placing the ball-milled slurry in an oven for drying to obtain a mixed powder;
[0029] Step 3: The mixed powder obtained in step 2 is granulated, aged, dry-pressed and fired to obtain low-expansion cordierite ceramics.
[0030] The chemical composition of the chlorite in the step 1 is as follows in mass percentage: SiO2 32.45%, Al2O3 16.06%, Fe2O3 0.5%, TiO2 0.64%, CaO 0.05%, MgO 35.64%, K2O 0.04%, Na2O 0.02%, and loss on ignition 14.6%.
[0031] In the step 1, the chlorite is ball-milled for 30 minutes and then passed through a 120-mesh sieve. The fineness of the kaolin is passed through an 80-mesh sieve. The fineness of the alumina is passed through a 120-mesh sieve. The weight ratio of chlorite:kaolin:alumina is 29.8:60.7:9.5.
[0032] The wet ball milling process in step 1 is performed for 20 minutes, the calcination process is performed at a temperature of 900° C. and the holding time is 1 hour, and the fineness of the pulverization process is such that the product passes through a 250-mesh sieve.
[0033] In the step 2, the weight ratio of cordierite precursor to fused quartz is 29.8:0.5.
[0034] The weight ratio of material: water: ball mill in the ball milling process in step 2 is 1:4:1.5, the ball milling time is 30 minutes, the fineness is passed through an 80-mesh sieve, the temperature of the drying process is 80° C., and the drying time is 12 hours.
[0035] The particle size of the granulation process in step 3 is over 80 mesh, the time of the aging process is 2 hours, the pressure of the dry pressing process is 10 MPa, and the holding time is 40 seconds.
[0036] The firing system of the firing process in step three is: the heating rate from 50 to 600°C is 2.5°C / min, the heating rate from 600 to 1000°C is 4°C / min, the heating rate from 1000 to 1300°C is 3°C / min, the holding time at the highest firing temperature is 3 hours, and then the temperature is lowered with the furnace.
[0037] The chemical composition of the low-expansion cordierite ceramic is as follows in percentage by mass: SiO2 47.8%, Al2O3 38.2%, CaO 0.5%, MgO 13.4%, Fe2O3 0.1%, TiO2 0.19%, K2O 0.01%, and Na2O 0.009%.
[0038] Example 2
[0039] A method for preparing low-expansion cordierite ceramics using chlorite comprises the following steps:
[0040] Step 1: Using chlorite as raw material, after ball milling and screening, adding a certain amount of kaolin and alumina and mixing evenly, and then wet ball milling, calcining, and crushing to obtain a cordierite precursor;
[0041] Step 2: adding a certain amount of fused quartz to the cordierite precursor obtained in step 1, placing the ball-milled slurry in an oven for drying to obtain a mixed powder;
[0042] Step 3: The mixed powder obtained in step 2 is granulated, aged, dry-pressed and fired to obtain low-expansion cordierite ceramics.
[0043] The chemical composition of the chlorite in the step 1 is as follows in mass percentage: SiO2 33.72%, Al2O3 15.86%, Fe2O3 0.6%, TiO2 0.54%, CaO 0.07%, MgO 35.54%, K2O 0.06%, Na2O 0.01%, and loss on ignition 13.6%.
[0044] In the step 1, the chlorite is ball-milled for 30 minutes and then passed through an 80-mesh sieve, the fineness of the kaolin is passed through a 40-mesh sieve, and the fineness of the alumina is passed through a 120-mesh sieve. The weight ratio of chlorite:kaolin:alumina is 32.4:54.7:12.9.
[0045] The wet ball milling process in step 1 is performed for 30 minutes, the calcination process is performed at a temperature of 800° C. and the holding time is 2 hours, and the fineness of the pulverization process is such that the product passes through a 250-mesh sieve.
[0046] In the step 2, the weight ratio of cordierite precursor to fused quartz is 29.8:10.
[0047] In the ball milling process of step 2, the weight ratio of material: water: ball mill is 1:4:1.5, the ball milling time is 20 minutes, the fineness is passed through an 80-mesh sieve, the temperature of the drying process is 80° C., and the drying time is 12 hours.
[0048] The particle size of the granulation process in step 3 is to pass through an 80-mesh sieve, the time of the aging process is 2 hours, the pressure of the dry pressing process is 5 MPa, and the holding time is 40 seconds.
[0049] The firing system of the firing process in step three is as follows: the heating rate of 50-600°C is 3.5°C / min, the heating rate of 600-1000°C is 4°C / min, the heating rate of 1000-1320°C is 2°C / min, the holding time at the highest firing temperature is 4h, and then the temperature is lowered with the furnace.
[0050] The chemical composition of the low-expansion cordierite ceramic is as follows in percentage by mass: SiO2 48.3%, Al2O3 38.8%, CaO 0.5%, MgO 12.35%, Fe2O3 0.05%, TiO2 0.16%, K2O 0.02%, and Na2O 0.003%.
[0051] Example 3
[0052] A method for preparing low-expansion cordierite ceramics using chlorite comprises the following steps:
[0053] Step 1: Using chlorite as raw material, after ball milling and screening, adding a certain amount of kaolin and alumina and mixing evenly, and then wet ball milling, calcining, and crushing to obtain a cordierite precursor;
[0054] Step 2: adding a certain amount of fused quartz to the cordierite precursor obtained in step 1, placing the ball-milled slurry in an oven for drying to obtain a mixed powder;
[0055] Step 3: The mixed powder obtained in step 2 is granulated, aged, dry-pressed and fired to obtain low-expansion cordierite ceramics.
[0056] The chemical composition of the chlorite in the step 1 is as follows in mass percentage: SiO2 32.76%, Al2O3 15.965%, Fe2O3 0.55%, TiO2 0.6%, CaO 0.06%, MgO 35.6%, K2O 0.05%, Na2O 0.015%, and loss on ignition 14.4%.
[0057] In the step 1, the chlorite is ball-milled for 30 minutes and then passed through a 120-mesh sieve, the fineness of the kaolin is passed through an 80-mesh sieve, and the fineness of the alumina is passed through a 160-mesh sieve. The weight ratio of chlorite:kaolin:alumina is 29.8:63.5:6.7.
[0058] The wet ball milling process in step 1 is carried out for 30 minutes, the calcination process is carried out at a temperature of 850° C. and a holding time of 1.5 hours, and the fineness of the pulverization process is such that the product passes through a 250-mesh sieve.
[0059] In the step 2, the weight ratio of cordierite precursor to fused quartz is 29.8:0.5.
[0060] In the ball milling process of step 2, the weight ratio of material: water: ball mill is 1:5:2.5, the ball milling time is 30 minutes, the fineness is passed through an 80-mesh sieve, the temperature of the drying process is 80° C., and the drying time is 12 hours.
[0061] The particle size of the granulation process in step 3 is to pass through a 100-mesh sieve, the time of the aging process is 4 hours, the pressure of the dry pressing process is 10 MPa, and the holding time is 30 seconds.
[0062] The firing system of the firing process in step three is as follows: the heating rate of 50-600°C is 2.5°C / min, the heating rate of 600-1000°C is 5°C / min, the heating rate of 1000-1360°C is 2°C / min, the holding time at the highest firing temperature is 2h, and then the temperature is lowered with the furnace.
[0063] The chemical composition of the low-expansion cordierite ceramic is as follows in percentage by mass: SiO2 47.3%, Al2O3 39.1%, CaO 0.6%, MgO 12.9%, Fe2O3 0.1%, TiO2 0.18%, K2O 0.015%, and Na2O 0.004%.
[0064] Example 4
[0065] A method for preparing low-expansion cordierite ceramics using chlorite comprises the following steps:
[0066] Step 1: Using chlorite as raw material, after ball milling and screening, adding a certain amount of kaolin and alumina and mixing evenly, and then wet ball milling, calcining, and crushing to obtain a cordierite precursor;
[0067] Step 2: adding a certain amount of fused quartz to the cordierite precursor obtained in step 1, placing the ball-milled slurry in an oven for drying to obtain a mixed powder;
[0068] Step 3: The mixed powder obtained in step 2 is granulated, aged, dry-pressed and fired to obtain low-expansion cordierite ceramics.
[0069] The chemical composition of the chlorite in the step 1 is as follows in mass percentage: SiO2 32.6%, Al2O3 15.965%, Fe2O3 0.58%, TiO2 0.63%, CaO 0.06%, MgO 35.6%, K2O 0.05%, Na2O 0.015%, and loss on ignition 14.5%.
[0070] In the step 1, the chlorite is ball-milled for 30 minutes and then passed through a 100-mesh sieve, the fineness of the kaolin is passed through a 60-mesh sieve, and the fineness of the alumina is passed through a 160-mesh sieve. The weight ratio of chlorite:kaolin:alumina is 32.4:44.6:2.9.
[0071] The wet ball milling process in step 1 is carried out for 30 minutes, the calcination process is carried out at a temperature of 900° C. and a holding time of 2 hours, and the fineness of the pulverization process is such that the product passes through a 250-mesh sieve.
[0072] In the step 2, the weight ratio of cordierite precursor to fused quartz is 32.4:10.
[0073] In the ball milling process of step 2, the weight ratio of material: water: ball mill is 1:5:2.5, the ball milling time is 30 minutes, the fineness is passed through a 100-mesh sieve, the temperature of the drying process is 80° C., and the drying time is 12 hours.
[0074] The particle size of the granulation process in step 3 is to pass through a 100-mesh sieve, the time of the aging process is 3 hours, the pressure of the dry pressing process is 8 MPa, and the holding time is 35 seconds.
[0075] The firing system of the firing process in step three is as follows: the heating rate of 50-600°C is 2.5°C / min, the heating rate of 600-1000°C is 4.5°C / min, the heating rate of 1000-1360°C is 3°C / min, the holding time at the highest firing temperature is 2h, and then the temperature is lowered with the furnace.
[0076] The chemical composition of the low-expansion cordierite ceramic is as follows in percentage by mass: SiO2 48.8%, Al2O3 37.6%, CaO 0.6%, MgO 12.9%, Fe2O3 0.1%, TiO2 0.21%, K2O 0.016%, and Na2O 0.005%.
[0077] Example 5
[0078] A method for preparing low-expansion cordierite ceramics using chlorite comprises the following steps:
[0079] Step 1: Using chlorite as raw material, after ball milling and screening, adding a certain amount of kaolin and alumina and mixing evenly, and then wet ball milling, calcining, and crushing to obtain a cordierite precursor;
[0080] Step 2: adding a certain amount of fused quartz to the cordierite precursor obtained in step 1, placing the ball-milled slurry in an oven for drying to obtain a mixed powder;
[0081] Step 3: The mixed powder obtained in step 2 is granulated, aged, dry-pressed and fired to obtain low-expansion cordierite ceramics.
[0082] The chemical composition of the chlorite in the step 1 is as follows in mass percentage: SiO2 33.1%, Al2O3 15.965%, Fe2O3 0.58%, TiO2 0.63%, CaO 0.06%, MgO 35.6%, K2O 0.05%, Na2O 0.015%, and loss on ignition 14.0%.
[0083] In the step 1, the chlorite is ball-milled for 30 minutes and then passed through an 80-mesh sieve. The fineness of the kaolin is passed through an 80-mesh sieve. The fineness of the alumina is passed through a 140-mesh sieve. The weight ratio of chlorite:kaolin:alumina is 30:64.7:5.5.
[0084] The wet ball milling process in step 1 is carried out for 25 minutes, the calcination process is carried out at a temperature of 800° C. and the holding time is 1 hour, and the fineness of the pulverization process is such that the product passes through a 250-mesh sieve.
[0085] In the step 2, the weight ratio of cordierite precursor to fused quartz is 30:5.5.
[0086] In the ball milling process of step 2, the weight ratio of material: water: ball mill is 1:4.5:2, the ball milling time is 40 minutes, the fineness is passed through a 90-mesh sieve, the temperature of the drying process is 80° C., and the drying time is 12 hours.
[0087] The particle size of the granulation process in step 3 is to pass through a 90-mesh sieve, the time of the aging process is 3 hours, the pressure of the dry pressing process is 10 MPa, and the holding time is 40 seconds.
[0088] The firing system of the firing process in step three is as follows: the heating rate from 50 to 600°C is 3°C / min, the heating rate from 600 to 1000°C is 4°C / min, the heating rate from 1000°C to 1320°C is 2.5°C / min, the holding time at the highest firing temperature is 3 hours, and then the temperature is lowered with the furnace.
[0089] The chemical composition of the low-expansion cordierite ceramic is as follows in percentage by mass: SiO2 48.25%, Al2O3 38.33%, CaO 0.55%, MgO 12.7%, Fe2O3 0.07%, TiO2 0.19%, K2O 0.015%, and Na2O 0.005%.
[0090] The test results of the low expansion cordierite ceramics prepared in Examples 1-5 are shown in the following table.
[0091]
[0092] like Figure 2The diffraction peaks in the XRD test results of the low-expansion cordierite ceramics prepared in Examples 1-5 are consistent with the main crystal phase of cordierite (PDF#97-015-6362).
[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the principles and spirit of the present invention are included in the scope of protection of the present invention.
Claims
1. A method for preparing low-expansion cordierite ceramics using chlorite, characterized in that: The steps include: Step 1: Using chlorite as raw material, after ball milling and screening, adding a certain amount of kaolin and alumina and mixing evenly, and then wet ball milling, calcining, and crushing to obtain a cordierite precursor; Step 2: adding a certain amount of fused quartz to the cordierite precursor obtained in step 1, placing the ball-milled slurry in an oven for drying to obtain a mixed powder; Step 3: granulating, aging, dry pressing and firing the mixed powder obtained in step 2 to obtain low expansion cordierite ceramics; The chemical composition of the low expansion cordierite ceramic is as follows in percentage by mass: SiO2 47.3-48.8%, Al2O3 37.6-39.1%, CaO 0.5-0.6%, MgO 12.35-13.4%, Fe2O3 0.05-0.1%, K2O 0.01-0.02%, Na2O 0.003-0.009%, TiO2 0.16-0.21%; The chemical composition of the chlorite in the step 1 is as follows in mass percentage: SiO2 32.45-33.72%, Al2O3 15.86-16.06%, Fe2O3 0.5-0.6%, TiO2 0.54-0.64%, CaO 0.05-0.07%, MgO 35.54-35.64%, K2O 0.04-0.06%, Na2O 0.01-0.02%, and loss on ignition 13.6-14.6%.
2. The method according to claim 1, wherein: In the step 1, the chlorite is ball-milled for 30 minutes and then passed through an 80-120 mesh sieve, the fineness of the kaolin is passed through a 40-80 mesh sieve, the fineness of the alumina is passed through a 120-160 mesh sieve, and the weight ratio of chlorite:kaolin:alumina is 29.8-32.4:44.6-64.7:2.9-12.
9.
3. The method according to claim 1, wherein: The wet ball milling process in step 1 is carried out for 20 to 30 minutes, the calcination process is carried out at a temperature of 800 to 900° C. and the holding time is 1 to 2 hours, and the fineness of the pulverization process is such that the product passes through a 250-mesh sieve.
4. The method according to claim 1, wherein: In the step 2, the weight ratio of cordierite precursor to fused quartz is 29.8-32.4:0.5-10.
5. The method according to claim 1, wherein: In the ball milling process of step 2, the weight ratio of material: water: ball mill is 1:4-5:1.5-2.5, the ball milling time is 20-40 minutes, the fineness is passed through an 80-100 mesh sieve, the temperature of the drying process is 80° C., and the drying time is 12 hours.
6. The method according to claim 1, wherein: The particle size of the granulation process in step 3 is passed through an 80-100 mesh sieve, the time of the aging process is 2-4 hours, the pressure of the dry pressing process is 5-10 MPa, and the pressure holding time is 30-40 seconds.
7. The method according to claim 1, wherein: The firing system of the firing process in step three is as follows: the heating rate from 50 to 600°C is 2.5 to 3.5°C / min, the heating rate from 600 to 1000°C is 4 to 5°C / min, the heating rate from 1000°C to the maximum firing temperature is 2 to 3°C / min, the holding time at the maximum firing temperature is 2 to 4 hours, and then the temperature is lowered with the furnace, and the maximum firing temperature is 1300 to 1360°C.
8. The method according to claim 1, wherein: The low expansion cordierite ceramics obtained in step 3 have a crystallinity of 88.5-93.8%, a flexural strength of 40.12-43.38 MPa, and a thermal expansion coefficient of 1.86-2.53×10 -6 / ℃, water absorption rate is 2.23~2.96%, and bulk density is 2.185~2.445g / cm 3 .