Amorphous phase modified cordierite ceramic material and method of making same
By adding Na2O, B2O3, BaO, Al2O3, and SiO2 to cordierite ceramics to form low-expansion amorphous powder, the problem of firing cordierite ceramics within a narrow temperature range was solved, and ceramic materials with low thermal expansion, high density, and high strength were prepared.
Patent Information
- Application Number
- CN202511354488.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-22
- Publication Date
- 2026-01-06
- Estimated Expiration
- 2045-09-22
AI Technical Summary
Existing cordierite ceramic materials have a narrow temperature range during firing, are prone to deformation, and are difficult to achieve low thermal expansion and high density over a wide temperature range, resulting in low product qualification rate and insufficient strength.
By adding appropriate amounts of Na2O, B2O3, BaO, Al2O3, and SiO2, amorphous powder with low thermal expansion coefficients is formed at high temperatures. This serves as an additive, reducing the firing temperature of ceramics and widening the temperature range, promoting the densification process, and utilizing the liquid phase effect of the amorphous phase to enhance the strength and density of ceramics.
The firing temperature of cordierite ceramics was reduced to 1300–1410 ℃, the firing temperature range was widened to ±20 ℃, the water absorption rate was reduced to less than 6%, the flexural strength was increased to 60–90 MPa, and the coefficient of thermal expansion was reduced to less than 1.8×10-6 ℃-1.
Smart Images
Figure CN120841944B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of advanced ceramic materials technology, and in particular to an amorphous phase modified cordierite ceramic material and its preparation method. Background Technology
[0002] Low thermal expansion ceramic materials generally refer to those with an average coefficient of thermal expansion of less than 2.0 × 10⁻⁶ within the range of room temperature to 800℃. -6 ℃ -1 Low thermal expansion ceramic materials, compared to other ordinary ceramic materials, possess superior high-temperature resistance and thermal shock resistance. They maintain their stability under complex environments with high temperatures and rapid temperature changes, and are widely used in refractories, catalyst supports, electronic devices, and aerospace. Common low thermal expansion ceramic materials include cordierite ceramics, aluminum titanate ceramics, phosphate ceramics, and lithium ceramics. Lithium ceramics were once the most widely used low thermal expansion ceramic material, but their application has gradually been limited due to the high dependence on imported lithium raw materials and their high cost. Aluminum titanate ceramics have a very low coefficient of thermal expansion, even negative ones. However, their synthesis requires titanium oxide as a raw material, resulting in high raw material costs and low ceramic strength. Furthermore, aluminum titanate is unstable and easily decomposes at high temperatures, making aluminum titanate ceramic products rare. Phosphate low expansion materials are mainly based on sodium zirconium phosphate oxide ceramics, possessing a very low coefficient of expansion. However, phosphates have poor chemical stability, and the phosphorus and zirconium required for their synthesis are very expensive, thus limiting their application. Cordierite ceramics are composed of MgO-Al2O3-SiO2. The synthesis process does not require expensive raw materials, and theoretically they are easy to promote and apply. However, there are still some technical problems with cordierite ceramics that have not been solved, mainly in the following aspects.
[0003] The first challenge is the narrow firing temperature range of cordierite. The theoretical formation temperature of cordierite crystals is 1410–1430℃, very close to its melting point (1460℃). This means that even slight fluctuations in kiln temperature during firing can prevent cordierite formation or cause it to melt. Traditional ceramic materials, due to the presence of low-melting-point substances like K₂O and Na₂O, can form a liquid phase at relatively low temperatures during firing, promoting sintering and thus having a wider firing temperature range. However, cordierite ceramics, composed of MgO, Al₂O₃, and SiO₂, have a liquid phase formation temperature near the theoretical composition of cordierite that is very close to its melting point. Therefore, the formation of a liquid phase during firing inevitably leads to deformation. Adding low-melting-point substances like K₂O and Na₂O to promote low-temperature liquid phase formation would lead to the formation of crystals other than cordierite, significantly increasing the coefficient of thermal expansion of the ceramic material. Therefore, how to reduce the formation temperature of cordierite crystals and broaden the firing temperature range through additive technology, thereby preventing the softening and deformation of cordierite ceramic products, is a problem that the industry has been trying to solve. Secondly, there is the contradiction between the low thermal expansion and high density of cordierite ceramic materials. Low thermal expansion performance requires the composition of cordierite ceramics to be as close as possible to its theoretical crystal composition. However, the thermal expansion of cordierite crystals differs greatly along the three axes, inevitably leading to microcracks during firing and cooling, resulting in both low strength and low density. To increase the density of cordierite ceramics, a liquid phase must be filled around the cordierite crystals, which is obviously detrimental to the low thermal expansion performance of cordierite ceramics. Currently, the coefficient of thermal expansion of cordierite ceramic materials produced by domestic cordierite manufacturers is all around 2.0 × 10⁻⁶. -6 ℃ -1 Furthermore, the production primarily consists of powder materials, with very few dense, low-expansion cordierite ceramic materials and related products. Therefore, how to improve processes and methods to lower the firing temperature of cordierite ceramics, enabling the preparation of cordierite ceramic materials with low thermal expansion coefficients and high density under a wider temperature range, has always been a problem that materials researchers have been dedicated to exploring. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an amorphous phase modified cordierite ceramic material with simple process, low cost and superior performance, and its preparation method.
[0005] This invention is achieved through the following technical solution: an amorphous phase modified cordierite ceramic material, characterized in that: the chemical composition of the ceramic material by weight percentage is: SiO2 51.30~54.39%, Al2O3 31.43~34.68%, MgO 12.46~13.86%, B2O3 0.10~1.11%, BaO 0.01~0.11%, Na2O 0.05~0.50%.
[0006] The preparation method of the amorphous phase modified cordierite ceramic material is characterized by comprising the following steps:
[0007] Step 1: Mix 0.10% B2O3, 0.01% BaO, 0.05% Na2O, 0.81-9.00% SiO2, and 0.03-0.28% Al2O3 evenly, and obtain a low-expansion amorphous additive after high-temperature melting, water quenching, ball milling, sieving, and drying.
[0008] Step 2: Mix the low-expansion amorphous additive obtained in Step 1 with other components of the ceramic material according to their chemical composition by weight percentage, and then shape to obtain a ceramic green body.
[0009] Step 3: The ceramic green body obtained in Step 2 is fired at high temperature to obtain low thermal expansion cordierite ceramic.
[0010] In step one, the high-temperature melting temperature is 1560–1630 °C, the holding time is 1–3 hours, and the sieve mesh size is 100–250.
[0011] The molding process in step two includes dry powder granulation and pressing molding, clay plastic molding, or slurry injection molding.
[0012] The size and shape of the ceramic green body in step two can be set according to requirements.
[0013] The high-temperature firing process in step three involves heating to 1330–1410 °C at a heating rate of 5–15 °C / min and holding at that temperature for 1–3 h.
[0014] In step three, the average coefficient of thermal expansion of the low-thermal-expansion cordierite ceramic between room temperature and 800 °C is 1.34 × 10⁻⁶. -6 ~1.69×10 -6 ℃ -1 It has a water absorption rate of 2.3-5.7% and a flexural strength of 63-86 MPa.
[0015] The technical principle of this invention is to melt appropriate amounts of Na₂O, B₂O₃, BaO, Al₂O₃, and SiO₂ at high temperature to form a mixture with a thermal expansion coefficient of 3.3–3.6 × 10⁻⁶. -6 ℃ -1Amorphous powder is added as an additive to cordierite formulations. Since the liquidus temperature of this amorphous powder is between 1050 and 1200 °C, within this temperature range, the uniformly distributed amorphous powder in the ceramic green body will form a dispersed high-temperature liquid phase, significantly promoting the sintering of the green body and the densification process of the ceramic. This reduces the theoretical firing temperature of cordierite ceramics from 1430 °C to 1300–1410 °C, and widens its firing temperature range from ±5 °C to over ±20 °C. Furthermore, because the introduced amorphous powder itself has a low coefficient of thermal expansion and does not react with cordierite crystals, trace amounts of low-expansion amorphous powder will not significantly affect the thermal expansion properties of cordierite ceramics.
[0016] This technical solution has the following beneficial effects:
[0017] (1) Reduce the firing temperature of cordierite ceramics: The theoretical firing temperature of cordierite ceramics is around 1430 ℃. The firing temperature of the amorphous phase modified cordierite ceramic material prepared by this scheme can be reduced to 1300~1410 ℃, achieving a significant reduction in firing temperature.
[0018] (2) Expanding the firing temperature range of cordierite ceramics: The firing temperature range of traditional cordierite ceramics is very narrow, generally around ±5℃. Slight fluctuations in kiln temperature can lead to firing failure. By firing amorphous phase modified cordierite ceramic materials through this technical solution, the firing temperature range can be expanded to more than ±20℃, which significantly improves the firing qualification rate of cordierite ceramic products.
[0019] (3) Improve the density of cordierite ceramics: Cordierite ceramics fired using MgO-Al2O3-SiO2 system raw materials have low density because they cannot generate a liquid phase, and their water absorption rate is generally above 15%. The water absorption rate of amorphous phase modified cordierite ceramics prepared by this method can be reduced to less than 6%, thereby greatly improving the density of cordierite ceramic materials and products.
[0020] (4) Improve the strength of cordierite ceramics: Ordinary cordierite ceramics inevitably generate a large number of microcracks due to the inconsistent shrinkage of cordierite crystals in different directions during the firing and cooling process, resulting in a bending strength of only 20-40 MPa. In this technical solution, the uniformly distributed amorphous phase powder forms a dispersed liquid phase at high temperature. After cooling, the glass phase acts as a binder for the cordierite crystals. Since the elastic modulus of the glass phase is much smaller than that of the crystal, it can withstand a certain deformation. Therefore, the addition of the amorphous phase can, to a certain extent, avoid the formation of microcracks during the firing and cooling process of cordierite ceramics, thereby improving the strength of the material to 60-90 MPa.
[0021] (5) Reduce the coefficient of thermal expansion of cordierite ceramics: The coefficient of thermal expansion of cordierite ceramic materials prepared by ordinary processes is generally 2.0×10⁻⁶ between room temperature and 800℃. -6 ℃ -1 The amorphous phase modified cordierite ceramic material prepared using this technical solution has a coefficient of thermal expansion of 1.8 × 10⁻⁶ within the same temperature range. -6 ℃ -1 Within. Attached Figure Description
[0022] Figure 1 The ceramic phase analysis diagram of the cordierite synthesized in Example 1 is shown.
[0023] Figure 2 The graph shows the thermal expansion coefficient of the cordierite synthesized in Example 1. Detailed Implementation
[0024] To further illustrate the present invention, the technical means and effects adopted to achieve the intended purpose of the invention, the present invention will be described in detail below with reference to preferred embodiments: Example 1
[0025] An amorphous phase modified cordierite ceramic material, wherein the chemical composition of the ceramic material by weight percentage is: SiO2 51.30%, Al2O3 34.68%, MgO 13.86%, B2O3 0.10%, BaO 0.01%, Na2O 0.05%. The SiO2, Al2O3, and MgO are introduced through kaolin and talc, the insufficient Al2O3 is introduced with industrially pure Al2O3, the B2O3 is introduced with boric acid, and the BaO and Na2O are introduced with their carbonates.
[0026] The preparation method of the amorphous phase modified cordierite ceramic material includes the following steps:
[0027] Step 1: Mix 0.10% B2O3, 0.01% BaO, 0.05% Na2O, 0.81% SiO2, and 0.03% Al2O3 evenly, and obtain a low-expansion amorphous additive after high-temperature melting, water quenching, ball milling, sieving, and drying.
[0028] Step 2: Mix the low-expansion amorphous additive obtained in Step 1 with other components of the ceramic material according to their chemical composition by weight percentage, and then shape to obtain a ceramic green body.
[0029] Step 3: The ceramic green body obtained in Step 2 is fired at high temperature to obtain low thermal expansion cordierite ceramic.
[0030] In step one, the high-temperature melting temperature is 1630 ℃, the holding time is 1 h, and the sieve mesh size is 100.
[0031] In step two, the molding process involves dry powder granulation and pressing. Specifically, the raw materials are mixed evenly, then water and a ball mill are added and fully ball-milled to prepare a slurry. The slurry is then prepared into near-spherical particles of 1-3 mm by spray granulation and pressed to obtain a ceramic green body.
[0032] In step two, the size and shape of the ceramic green body can be set according to requirements, such as pressing it into a disc with a diameter of 300 mm and a thickness of 6 mm using a mold.
[0033] The high-temperature firing process in step three involves heating to 1410°C at a heating rate of 5°C / min and holding at that temperature for 1 hour.
[0034] In step three, the average coefficient of thermal expansion of the low-thermal-expansion cordierite ceramic between room temperature and 800 °C is 1.34 × 10⁻⁶. -6 ℃ -1 The water absorption rate is 5.7%, and the flexural strength is 63 MPa. The phase analysis of the synthesized cordierite is shown in the figure. Figure 1 Analysis of thermal expansion coefficient is shown in [reference]. Figure 2 . Example 2
[0035] An amorphous phase modified cordierite ceramic material, wherein the chemical composition of the ceramic material by weight percentage is: SiO2 52.53%, Al2O3 33.38%, MgO 13.30%, B2O3 0.51%, BaO 0.05%, Na2O 0.23%. The SiO2, Al2O3, and MgO are introduced through kaolin and talc, the insufficient Al2O3 is introduced with industrially pure Al2O3, the B2O3 is introduced with boric acid, and the BaO and Na2O are introduced with their carbonates.
[0036] The preparation method of the amorphous phase modified cordierite ceramic material includes the following steps:
[0037] Step 1: Mix 0.10% B2O3, 0.01% BaO, 0.05% Na2O, 4.08% SiO2, and 0.13% Al2O3 evenly, and obtain a low-expansion amorphous additive after high-temperature melting, water quenching, ball milling, sieving, and drying.
[0038] Step 2: Mix the low-expansion amorphous additive obtained in Step 1 with other components of the ceramic material according to their chemical composition by weight percentage, and then shape to obtain a ceramic green body.
[0039] Step 3: The ceramic green body obtained in Step 2 is fired at high temperature to obtain low thermal expansion cordierite ceramic.
[0040] In step one, the high-temperature melting temperature is 1590 ℃, the holding time is 2 h, and the sieve mesh size is 150.
[0041] In step two, the molding process is slip casting. The specific steps are as follows: after the raw materials in step two are mixed evenly, water and a ball mill are added and the mixture is fully ball-milled to prepare a slurry. The ceramic green body is then obtained by slip casting using a plaster mold.
[0042] In step two, the size and shape of the ceramic green body can be set according to requirements, such as slip casting to form a ceramic green body for teaware with a diameter of 160 mm, a height of 100 mm, and a thickness of 5 mm.
[0043] The high-temperature firing process in step three involves heating to 1360°C at a heating rate of 10°C / min and holding at that temperature for 2 hours.
[0044] In step three, the average coefficient of thermal expansion of the low-thermal-expansion cordierite ceramic between room temperature and 800°C is 1.56 × 10⁻⁶. -6 ℃ -1 It has a water absorption rate of 4.2% and a flexural strength of 77 MPa. Example 3
[0045] An amorphous phase modified cordierite ceramic material, wherein the chemical composition of the ceramic material by weight percentage is: SiO2 54.39%, Al2O3 31.43%, MgO 12.46%, B2O3 1.11%, BaO 0.11%, Na2O 0.50%. The SiO2, Al2O3, and MgO are introduced through kaolin and talc, the insufficient Al2O3 is introduced with industrially pure Al2O3, the B2O3 is introduced with boric acid, and the BaO and Na2O are introduced with their carbonates.
[0046] The preparation method of the amorphous phase modified cordierite ceramic material includes the following steps:
[0047] Step 1: Mix 0.10% B2O3, 0.01% BaO, 0.05% Na2O, 9.00% SiO2, and 0.28% Al2O3 evenly, and obtain a low-expansion amorphous additive after high-temperature melting, water quenching, ball milling, sieving, and drying.
[0048] Step 2: Mix the low-expansion amorphous additive obtained in Step 1 with other components of the ceramic material according to their chemical composition by weight percentage, and then shape to obtain a ceramic green body.
[0049] Step 3: The ceramic green body obtained in Step 2 is fired at high temperature to obtain low thermal expansion cordierite ceramic.
[0050] In step one, the high-temperature melting temperature is 1560 ℃, the holding time is 3 hours, and the sieve mesh size is 250.
[0051] In step two, the molding process involves shaping the clay into a plastic material. The specific steps are as follows: after the raw materials in step two are mixed evenly, water and a ball mill are added and the mixture is fully ball-milled to prepare a slurry. Then, excess water is squeezed out through a filter cloth and the clay is vacuum-kneaded into a plastic material. Finally, a ceramic green body is obtained by rolling.
[0052] In step two, the size and shape of the ceramic green body can be set according to requirements, such as rolling it into a ceramic green body for cookware with a diameter of 260 mm, a height of 200 mm, and a thickness of 5 mm.
[0053] The high-temperature firing process in step three involves heating to 1330°C at a heating rate of 15°C / min and holding at that temperature for 3 hours.
[0054] In step three, the average coefficient of thermal expansion of the low-thermal-expansion cordierite ceramic between room temperature and 800°C is 1.69 × 10⁻⁶. -6 ℃ -1 It has a water absorption rate of 2.3% and a flexural strength of 86 MPa.
[0055] 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 within the protection scope of the present invention.
Claims
1. A method for producing an amorphous phase modified cordierite ceramic material, characterized by It comprises the following steps: Step one: uniformly mix 0.10% B2O3, 0.01% BaO, 0.05% Na2O and 0.81-9.00% SiO2, 0.03-0.28% Al2O3, melt at high temperature, quench in water, ball mill, sieve, dry to obtain low-expansion amorphous additive; Step two: uniformly mix the low-expansion amorphous additive obtained in step one with other ingredients of the amorphous-phase-modified cordierite ceramic material in terms of chemical composition by weight percentage, and shape to obtain ceramic green body; Step three: high-temperature sintering of the ceramic green body obtained in step two to obtain the amorphous-phase-modified cordierite ceramic material; The chemical composition of the amorphous-phase-modified cordierite ceramic material by weight percentage is: SiO2 51.30-54.39%, Al2O3 31.43-34.68%, MgO 12.46-13.86%, B2O3 0.10-1.11%, BaO 0.01-0.11%, Na2O 0.05-0.50%.
2. The method of claim 1, wherein: The temperature of high-temperature melting in step one is 1560-1630℃, and the holding time is 1-3 hours; the mesh number of sieving is 100-250.
3. The method of claim 1, wherein: The shaping in step two includes dry powder granulation compression molding, clay plastic molding or grouting molding.
4. The method of claim 1, wherein: The high-temperature sintering system in step three is heating to 1330-1410℃ at a heating rate of 5-15℃ / min and holding for 1-3h.
5. The method of claim 1, wherein: The average thermal expansion coefficient of the non-crystalline phase modified cordierite ceramic material in step three is 1.43×10 -6 ~1.69×10 -6 ℃ -1 , the water absorption is 2.3~5.7%, and the bending strength is 63~86MPa.