High-purity cordierite ceramic powder and preparation method therefor
High-purity cordierite powder was synthesized through a two-stage high-temperature reaction method using high-purity MgO, Al2O3, and SiO2 powders. This method solves the problems of high impurity content and difficulty in mass production in existing technologies, and achieves the preparation of high-purity, highly reactive powder, which is suitable for fields such as precision measuring instruments and space telescopes.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-09-25
- Publication Date
- 2026-04-02
AI Technical Summary
Existing technologies struggle to synthesize high-purity, highly reactive cordierite powder, and existing methods suffer from problems such as high impurity content, incomplete reaction, high cost, and difficulty in mass production.
Using high-purity, highly reactive MgO, Al2O3, and SiO2 powders as raw materials, a partial cordierite phase is generated through an initial high-temperature reaction, which reduces the sintering activity. After dry pressing, a second high-temperature reaction is carried out to obtain loose and easily broken high-purity cordierite blocks, which are finally crushed into powder.
The synthesized phase has high purity, the process is simple, and it is easy to mass-produce, meeting the needs of high-end fields such as precision measuring instruments, space mirrors, and space telescopes.
Smart Images
Figure CN2025123946_02042026_PF_FP_ABST
Abstract
Description
High-purity cordierite ceramic powder and preparation method thereof TECHNICAL FIELD
[0001] The application belongs to the technical field of ceramic powder preparation, and particularly relates to a method for synthesizing high-purity cordierite ceramic powder by twice high-temperature reaction through high-purity and high-reactivity raw material powder. BACKGROUND
[0002] The cordierite ceramic has an ultra-low thermal expansion coefficient (10 -9 / K grade), high specific stiffness, good chemical stability, long-term dimensional stability and other advantages, and has great application potential in the fields of precision measuring instruments, space mirrors, space telescopes and precision semiconductor components, etc.
[0003] The solid phase reaction method mainly includes two kinds: one is a natural mineral solid phase reaction method, which uses natural minerals as raw materials, mixes uniformly and then reacts in solid phase, but the phase purity of the synthesized cordierite powder is low due to the large amount of impurities in the natural minerals. The other is an oxide solid phase reaction method, which uses oxides as raw materials, mixes uniformly and then reacts in solid phase. Although the phase purity of the synthesized powder is high, the impurity content in the powder is low, the reaction activity is reduced, the reaction temperature is increased, and the oxides are difficult to react completely, so the synthesized powder contains some impurities.
[0004] The wet chemical method uses liquid chemical reagents as raw materials. The reactants are mixed uniformly in liquid phase and then react, and the reaction product is a stable sol system which is converted into a gel after a certain period of time, and then the cordierite powder is prepared after drying and high-temperature treatment. Compared with other preparation processes, it has the characteristics of small particle size, high activity, simple process, uniform multi-component doping and relatively low processing temperature. However, the disadvantages are also obvious, such as expensive raw materials, very harsh process, harmful impurities, long preparation period, and sometimes residual fine pores or carbon that cause the product to turn black.
[0005] The molten glass crystallization method is to mix the batch materials uniformly, then melt into a glass state at high temperature, and then perform heat treatment to precipitate crystals to prepare the cordierite powder. This method requires uniform glass melting without bubbles, and the melting temperature is also high, which needs to reach more than 1600 DEG C. The powder yield depends on the size of the equipment, and large-scale production requires expensive large equipment, which is not conducive to low-cost mass production, and it is difficult to ensure the stability of the powder batches and the stability of the subsequent ceramic performance. SUMMARY
[0006] To address the aforementioned technical problems, the present invention aims to provide a high-purity cordierite ceramic powder and its preparation method.
[0007] In a first aspect, the present invention provides a method for preparing high-purity cordierite ceramic powder, the method comprising the following steps: (1) mixing high-purity, highly reactive MgO, Al2O3 and SiO2 powders according to the cordierite chemical composition, drying and sieving to obtain mixed raw material powder; (2) subjecting the mixed raw material powder to a primary high-temperature reaction at 1200-1400℃ to reduce the sintering activity of the powder, cooling and then dry pressing to obtain a green body block; (3) subjecting the green body block to a secondary high-temperature reaction at 1450-1460℃ to partially melt the interior of the green body and generate a liquid phase, cooling to obtain a loose and easily breakable high-purity cordierite block; (4) crushing the high-purity cordierite block to the target particle size to obtain the high-purity cordierite ceramic powder.
[0008] Preferably, in step (1), the high-purity, highly reactive MgO powder has a purity ≥ 99.99% and a particle size D. 100 The wavelength range is 150–650 nm, and the specific surface area is 15–20 m². 2 / g; The high-purity, highly reactive Al2O3 powder has a purity ≥99.99% and a particle size D 100 The wavelength ranges from 250 to 750 nm, and the specific surface area is 10 to 15 m². 2 / g; The high-purity, highly reactive SiO2 powder has a purity ≥99.99% and a particle size D 100 The wavelength ranges from 200 to 700 nm, and the specific surface area is 10 to 15 m². 2 / g.
[0009] Preferably, in step (1), according to the chemical composition of cordierite, the content of MgO powder is 13.0-15.0 wt%, the content of Al2O3 powder is 33.0-35.0 wt%, and the content of SiO2 powder is 51.0-53.0 wt% by weight.
[0010] Preferably, in step (1), the raw material powder is mixed by roller ball milling, the solvent is deionized water, the grinding balls are zirconia balls, the roller speed is 60-90 rpm, and the ball milling time is 12-24 h.
[0011] Preferably, in step (1), the drying temperature is 80-110℃ and the drying time is 12-16h; the sieving is performed by the powder passing through an 80-mesh nylon sieve; and the particle size of the mixed raw material powder is ≤180μm.
[0012] Preferably, in step (2), the atmosphere of the initial high-temperature reaction is an air atmosphere, and the reaction time is 1 to 10 hours.
[0013] Preferably, in step (2), the pressure for dry pressing is 20-60 MPa, and the pressure holding time is 5-60 s.
[0014] Preferably, in step (3), the atmosphere for the secondary high-temperature reaction is air, and the reaction time is 1-10 h.
[0015] Preferably, in step (4), the method for crushing is to first coarsely crush the cordierite block by using a hammer crusher, a jaw crusher or a roller crusher, and then to pulverize the coarsely crushed block to a target particle size by using a mechanical mill, an air flow mill and a sand mill.
[0016] In a second aspect, the present application provides a high-purity cordierite ceramic powder obtained by the above preparation method, wherein the phase purity of the high-purity cordierite ceramic powder is ≥ 99.8 wt%.
[0017] The cordierite powder preparation method provided by the present application has high synthesis phase purity, simple process, easy-to-control preparation conditions, and is easy to mass produce, and can meet the needs of cordierite ceramics in high-end fields such as precision measuring instruments, space mirrors, space telescopes and precision semiconductor components. BRIEF DESCRIPTION OF DRAWINGS
[0018] FIG. 1 is an XRD pattern of the high-purity cordierite ceramic powder prepared in Example 1; FIG. 2 is an XRD pattern of the cordierite ceramic powder prepared in Example 2; FIG. 3 is an XRD pattern of the cordierite ceramic powder prepared in Example 3; FIG. 4 is an XRD pattern of the cordierite powder prepared in Comparative Example 1; FIG. 5 is an XRD pattern of the cordierite powder prepared in Comparative Example 2; and FIG. 6 is an XRD pattern of the cordierite powder prepared in Comparative Example 3. DETAILED DESCRIPTION
[0019] The present application will be further described below by the following examples, which should be understood as merely illustrative of the present application, but not limiting the present application.
[0020] The present application uses high-purity and high-reactivity MgO, Al2O3 and SiO2 as raw material powders, and after mixing, a part of cordierite phase is generated and the sintering activity is reduced by a primary high-temperature reaction, and then dry pressing is performed, and then a high-purity and loose cordierite block is obtained by a secondary high-temperature reaction, and finally a high-purity cordierite powder is obtained by crushing.
[0021] Hereinafter, a preparation method of high-purity cordierite ceramic powder provided by the present application is exemplarily described. The preparation method can include the following steps: (1) high-purity and high-reactivity MgO, Al2O3 and SiO2 powders are proportioned according to the chemical composition of cordierite and mixed, and then dried and sieved to obtain mixed raw material powders; (2) the mixed raw material powders are subjected to primary high-temperature reaction at 1200-1400°C to reduce the sintering activity of the powders, and then cold-pressed to form a green body after cooling; (3) the green body is subjected to secondary high-temperature reaction at 1450-1460°C to make part of the green body melt and generate liquid phase, and then cooled to obtain a loose and easily broken high-purity cordierite block; and (4) the high-purity cordierite block is broken to a target particle size to obtain the high-purity cordierite ceramic powder.
[0022] In some embodiments, in step (1), the high-purity and high-reactivity MgO powder has a purity of ≥99.99%, a particle size D 100 of 150-650 nm and a specific surface area of 15-20 m 2 / g; the high-purity and high-reactivity Al2O3 powder has a purity of ≥99.99%, a particle size D 100 of 250-750 nm and a specific surface area of 10-15 m 2 / g; and the high-purity and high-reactivity SiO2 powder has a purity of ≥99.99%, a particle size D 100 of 200-700 nm and a specific surface area of 10-15 m 2 / g.
[0023] In some embodiments, in step (1), the raw material particle size and the specific surface area are in a positive correlation relationship, and a too large raw material particle size will reduce the reaction activity, causing the raw materials to be difficult to react and not fully reacted, and the phase purity of the synthesized ceramic powder to be reduced; and a too small raw material particle size will easily cause agglomeration, causing the raw materials to be difficult to uniformly dispersed, and eventually causing the phase purity of the synthesized ceramic powder to be reduced and other impurity phases to be generated.
[0024] In some embodiments, in step (1), the raw materials are proportioned according to the chemical composition of cordierite, and the content of the MgO powder is 13.0-15.0 wt%, the content of the Al2O3 powder is 33.0-35.0 wt%, and the content of the SiO2 powder is 51.0-53.0 wt% according to the weight fraction. Only when the amount proportion of each raw material powder is controlled within this range can the high-purity phase ceramic powder be synthesized, and an excessive or insufficient amount proportion of each raw material powder will reduce the phase purity of the ceramic powder and generate other impurity phases.
[0025] In some embodiments, in step (1), the raw material powder mixing method can be drum ball milling, deionized water is used as the solvent, zirconia balls are used as the milling balls, the drum rotation speed is 60-90 rpm, and the ball milling mixing time is 12-24 h.
[0026] In some embodiments, in step (1), the drying temperature is 80-110℃, and the drying time is 12-16h; the sieving is through 60-100 mesh nylon sieve, preferably 80 mesh nylon sieve, and more preferably, the particle size of the sieved mixed raw material powder is ≤180μm. If the sieve mesh number is too large, the sieving will be difficult, and the production efficiency will be reduced; if the sieve mesh number is too small, the next step will be difficult to form.
[0027] In some embodiments, in step (2), the atmosphere of the initial high-temperature reaction is air atmosphere, the reaction time is 1-10h, preferably 1-5h; the dry pressing forming pressure is 20-60MPa, and the pressure holding time is 5-60s.
[0028] After the initial high-temperature reaction, part of the cordierite phase is generated, and the sintering activity is reduced. The part of the cordierite produces a "seed crystal" effect, which makes the surrounding phase powder more easily generate cordierite phase in the subsequent second high-temperature reaction. At the same time, the powder after the initial high-temperature reaction is dry pressed into a block, so that the contact area between the powders is larger, and the "seed crystal" effect is more obvious in the subsequent second high-temperature reaction, and the powder reaction is more sufficient.
[0029] If the initial high-temperature reaction temperature is too high, the mixed raw material powder will melt and the experiment will fail; if the initial high-temperature reaction temperature is too low, the final breaking stage will be difficult to proceed smoothly; if the holding time is too long, it will be wasted; if the holding time is too short, the purity of the ceramic powder will be reduced; if the dry pressing pressure is too large or the dry pressing time is too long, the press equipment will be damaged; if the dry pressing pressure is too small or the dry pressing time is too short, it will be difficult to form.
[0030] In some embodiments, in step (3), the atmosphere of the second high-temperature reaction is air atmosphere, and the reaction time is 1-10h, preferably 1-5h.
[0031] In the second high-temperature reaction, the temperature is controlled within 10℃ of the melting point of the green body, at which time the green body will partially melt to produce a liquid phase, the substance transport speed will greatly increase, the powder reaction rate will greatly increase, the reaction will be more sufficient, and then the high-purity cordierite block will be obtained. If the second high-temperature reaction temperature is too high or the time is too long, the green body will melt; if the second high-temperature reaction temperature is too low or the time is too short, the phase purity of the synthesized powder will be reduced, and other impurities will be produced.
[0032] In some embodiments, in step (4), the breaking method can be that the cordierite block is first coarsely broken by a hammer crusher, a jaw crusher or a roller crusher, and then is pulverized to the target particle size by a mechanical mill, an air flow mill and a sand mill.
[0033] The application selects high-purity and high-reactivity MgO, Al2O3 and SiO2 powder as raw materials, mixes the powder uniformly, and synthesizes part of cordierite and reduces the sintering activity of the powder through primary high-temperature reaction. The part of cordierite produces a similar effect of "seed crystal", which makes the surrounding phase powder more easily generate cordierite phase in subsequent secondary high-temperature reaction. Then, the application dry-presses the powder after the primary high-temperature reaction into a block, so that the contact area between the powder is larger, and in the secondary high-temperature reaction, the effect of "seed crystal" is more obvious, and the powder reaction is more sufficient. At the same time, in the secondary high-temperature reaction, the temperature is controlled within 10℃ below the melting point of the green body, at this time, the green body will be partially melted to produce a liquid phase, the substance transportation speed is greatly increased, the powder reaction rate is greatly improved, the reaction is more sufficient, and then high-purity cordierite block is obtained. At the same time, due to the reduction of sintering activity in the primary high-temperature reaction, the obtained cordierite block is loose and easy to break.
[0034] The total content of α-cordierite and β-cordierite in the prepared cordierite powder is tested by Rietveld structure refinement. The phase purity of the high-purity cordierite ceramic powder obtained by the preparation method provided by the application is ≥99.8wt%, which is beneficial to the preparation of ultra-low expansion ceramic, and the operation is simple, easy to mass produce at low cost and high efficiency.
[0035] The following further illustrates the embodiments to further illustrate the application. It should also be understood that the following embodiments are only used to further illustrate the application, and cannot be understood as limiting the protection scope of the application. Some non-essential improvements and adjustments made by those skilled in the art according to the above content of the application are within the protection scope of the application. The specific process parameters in the following examples are only one example in the appropriate range, i.e. those skilled in the art can select within the appropriate range according to the description herein, and are not limited to the specific values in the following examples.
[0036] The application tests the total content of α-cordierite and β-cordierite in cordierite ceramic by Rietveld structure refinement. Those skilled in the art can know that the steps not specifically shown in the testing and preparation process can be determined according to the conventional technical means known by those skilled in the art.
[0037] Example 1
[0038] The preparation method of the high-purity cordierite ceramic powder provided in the embodiment comprises the following steps: (1) high-purity, high-reactivity MgO, Al2O3 and SiO2 powders are weighed according to the mass percentage of 13.5wt%, 34.5wt% and 52.0wt%, respectively, and then deionized water and zirconia balls are added, and a drum ball mill is used for ball milling and mixing at 90 rpm, and the mixture is discharged after mixing for 20 h to obtain a uniformly mixed slurry; the mixed slurry is placed in an oven at 110℃ and dried for 12 h, and then sieved through an 80-mesh sieve to obtain a uniformly mixed raw material powder with a particle size range of ≤180 μm; (2) the mixed raw material powder in step (1) is subjected to a primary high-temperature reaction at 1200℃ for 2 h to generate part of the cordierite phase and reduce the sintering activity of the powder, and then dry pressing (50 MPa, pressure maintaining for 5 s) is performed to obtain a green body block; (3) the green body block in step (2) is subjected to a secondary high-temperature reaction at 1450℃ for 2 h, and after cooling, a loose and easily broken high-purity cordierite block is obtained; (4) the high-purity cordierite block in step (3) is broken, and coarse crushing is performed on the broken block by using a roll crusher, and then the broken block is crushed to a target particle size by using an air jet mill and a sand mill to obtain the high-purity cordierite ceramic powder.
[0039] Figure 1 is an XRD pattern of the high-purity cordierite ceramic powder prepared in Example 1. As can be seen from the figure, the content of cordierite in the high-purity phase cordierite ceramic powder obtained in Example 1 is 99.8wt%.
[0040] Example 2
[0041] The preparation method of the high-purity cordierite ceramic powder provided in the embodiment refers to Example 1, and the main difference lies in that: in step (2), the primary high-temperature reaction is at 1300℃ for 2 h; in step (3), the secondary high-temperature reaction is at 1455℃ for 2 h.
[0042] Figure 2 is an XRD pattern of the cordierite ceramic powder prepared in Example 2. As can be seen from the figure, the content of cordierite in the high-purity phase cordierite ceramic powder obtained in Example 2 is 100wt%.
[0043] Example 3
[0044] The preparation method of the high-purity cordierite ceramic powder provided in the embodiment refers to Example 1, and the main difference lies in that: in step (2), the primary high-temperature reaction is at 1400℃ for 2 h; in step (3), the secondary high-temperature reaction is at 1460℃ for 2 h.
[0045] Figure 3 is an XRD pattern of the cordierite ceramic powder prepared in Example 3. As can be seen from the figure, the content of cordierite in the high-purity phase cordierite ceramic powder obtained in Example 3 is 99.8wt%.
[0046] Comparative Example 1
[0047] The preparation method of the cordierite ceramic powder provided in the present comparative example refers to that of Example 1, the main difference being that in step (2), the initial high-temperature reaction is not performed, and the mixed raw material powder is directly dry-pressed to form a green body which is subjected to high-temperature reaction at 1450°C.
[0048] Figure 4 is an XRD pattern of the cordierite powder prepared in Comparative Example 1. As can be seen from the figure, the cordierite content in the cordierite ceramic powder obtained in Comparative Example 1 is only 96.7wt%, and contains a small amount of mullite phase and corundum phase. Moreover, the cordierite block prepared in the present comparative example is not dense and is difficult to break, and is difficult to mass-produce.
[0049] Comparative Example 2
[0050] The preparation method of the cordierite ceramic powder provided in the present comparative example refers to that of Example 1, the main difference being that in step (2), the initial high-temperature reaction is not performed, and the mixed raw material powder is directly dry-pressed to form a green body which is subjected to high-temperature reaction at 1450°C.
[0051] Figure 5 is an XRD pattern of the cordierite powder prepared in Comparative Example 2. As can be seen from the figure, the cordierite content in the cordierite ceramic powder obtained in Comparative Example 2 is only 97.0wt%, and contains a small amount of mullite and corundum phases due to incomplete reaction.
[0052] Comparative Example 3
[0053] The preparation method of the cordierite ceramic powder provided in the present comparative example refers to that of Example 2, the main difference being that in step (3), the temperature of the secondary high-temperature reaction is 1440°C.
[0054] Figure 6 is an XRD pattern of the cordierite powder prepared in Comparative Example 3. As can be seen from the figure, the cordierite content in the cordierite ceramic powder obtained in Comparative Example 3 is only 98.2wt%, and contains a small amount of mullite and corundum due to incomplete reaction.
[0055] Although the present application has been described in detail by means of the preferred embodiments, it should be recognized that such detailed description is by way of example only and that numerous modifications and substitutions can be made by those skilled in the art without departing from the scope of the application. Accordingly, the scope of the present application is defined only by the appended claims.
Claims
1. A method for preparing cordierite ceramic powder, characterized in that, The preparation method comprises the following steps: (1) MgO, Al2O3 and SiO2 powders are proportioned according to the chemical composition of cordierite and mixed, dried, and sieved to obtain mixed raw material powders; (2) the mixed raw material powders are subjected to primary high-temperature reaction at 1200-1400 ℃, and after cooling, dry pressing is performed to obtain a green body block; (3) the green body block is subjected to secondary high-temperature reaction at 1450-1460 ℃, and after cooling, a cordierite block is obtained; (4) the cordierite block is crushed to a target particle size to obtain the cordierite ceramic powder.
2. The production method according to claim 1, characterized by, In step (1), the purity of the MgO powder is ≥ 99.99%, the particle size D 100 is 150-650 nm, and the specific surface area is 15-20 m 2 / g. The purity of the Al2O3 powder is ≥99.99%, the particle size D 100 250-750 nm, and the specific surface area is 10-15 m 2 / g. The SiO2 powder has purity ≥ 99.99%, particle size D 100 200-700 nm, and specific surface area 10-15 m 2 / g.
3. The preparation method according to claim 1, characterized in that, In step (1), the raw material powders are mixed by drum ball milling, deionized water is used as the solvent, zirconia balls are used as the grinding balls, the drum rotation speed is 60-90 rpm, and the ball milling mixing time is 12-24 h.
4. The method of claim 1, wherein, In step (1), the drying temperature is 80-110 ℃, the drying time is 12-16 h; the sieving is powder passing through an 80-mesh nylon sieve; and the particle size of the mixed raw material powders is ≤180 μm.
5. The preparation method according to claim 1, characterized in that, In step (2), the primary high-temperature reaction is performed in an air atmosphere, and the reaction time is 1-10 h.
6. The method of claim 1, wherein, In step (2), the dry pressing is performed at a pressure of 20-60 MPa and a pressure holding time of 5-60 s.
7. The preparation method according to claim 1, characterized in that, In step (3), the secondary high-temperature reaction is performed in an air atmosphere, and the reaction time is 1-10 h.
8. The method of claim 1, wherein, In step (4), the crushing is performed by first coarsely crushing the cordierite block by using a hammer crusher, a jaw crusher or a roller crusher, and then pulverizing to the target particle size by using a mechanical mill, an air jet mill and a sand mill.
9. The method of claim 1, wherein, The phase purity of the cordierite ceramic powder is ≥99.8 wt%.
10. The cordierite ceramic powder obtained by the production method according to any one of claims 1 to 9, characterized in that