Preparation method of low-expansion high-strength epi-dioptase-cordierite composite ceramic body and product thereof

Abstract

The application discloses a kind of low expansion high-strength epi-dope-berylite ceramic body preparation method and its product, with industrial solid waste lithium residue as main raw material, with kaolin, borymagnesium, potassium feldspar jointly build Li-K-Mg-B multiple eutectic system, reduce sintering temperature to 1180~1200 ℃;While through raw material ratio control, in-situ generation epi-dope and berylite complex structure.The ceramic body prepared has high densification degree, and has excellent thermal stability and mechanical properties.The application realizes high value-added resource utilization of industrial solid waste lithium residue, has the advantages of low production cost, wide sintering temperature, green environmental protection and the like, and has important significance for resource utilization of industrial solid waste and development of low-expansion ceramic technology.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, and in particular to a method for preparing a low-expansion, high-strength multiphase ceramic green body and its products. Background Technology

[0002] Low-expansion ceramic materials have important applications in aerospace, precision instruments, and high-temperature industries. 18 ) and petalite (LiAlSi4O 10 Cordierite and lithium feldspar are two typical low-expansion crystalline materials. Cordierite has a low coefficient of thermal expansion but requires a high sintering temperature and has insufficient strength; lithium feldspar has an extremely low coefficient of thermal expansion but has high raw material costs and poor sintering performance when sintered alone. Combining the two can achieve synergistic performance, but how to sinter at low temperatures and control the multiphase structure remains a technical challenge.

[0003] Lithium slag is a large-scale industrial solid waste generated during the lithium extraction process, with an annual output of millions of tons. Its main components are SiO2, Al2O3, and residual Li2O. Currently, its disposal mainly relies on landfilling, which causes environmental pollution and resource waste. Existing technologies typically utilize Li2O from lithium slag as a flux, but there is still a lack of mature solutions for its efficient application in the petalite-cordierite multiphase system.

[0004] Therefore, developing a method for preparing lithium feldspar-cordierite multiphase ceramics using inexpensive raw materials such as lithium slag is of great significance for the resource utilization of industrial solid waste and the development of low-expansion ceramic technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing a low-expansion, high-strength lithium feldspar-cordierite multiphase ceramic body. Using industrial solid waste lithium slag as the main raw material, a Li-K-Mg-B multi-element eutectic system is constructed together with kaolin, borosilicate, and potassium feldspar, lowering the sintering temperature to 1180–1200℃. Simultaneously, by controlling the raw material ratio, a lithium feldspar and cordierite multiphase structure is generated in situ, resulting in a ceramic body with excellent low-expansion, high-strength properties. Another objective of this invention is to provide products prepared using the above method.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention provides a method for preparing a low-expansion, high-strength, lithium feldspar-cordierite multiphase ceramic green body. The raw material composition of the ceramic green body is 20-35 wt% lithium slag, 20-30 wt% kaolin, 10-20 wt% boromagnesia, 10-22 wt% potassium feldspar, and 12-20 wt% lepidolite. The chemical composition of the lithium slag is 82.64-86.12 wt% SiO2, 37.29-11.68 wt% Al2O, 0.07-0.24 wt% K2O, 0.05-0.17 wt% Na2O, 0.72-1.15 wt% Li2O, and 3.45-5.72 wt% Il. The preparation method includes the following steps:

[0008] (1) After mixing the raw materials according to the above composition, the mixture is placed in a ball mill for ball milling. Then the resulting slurry is dried, sieved, and granulated to obtain the material.

[0009] (2) After the material is pressed and shaped, it is heated from room temperature to 1180-1200℃ at a rate of 2-5℃ / min, and the holding time is 30-60min. Then, it is cooled down with the furnace and naturally cooled to room temperature to obtain a lithium feldspar-cordierite multiphase ceramic body.

[0010] Furthermore, in step (1) of the present invention, ball milling is performed at a mass ratio of material:ball:water = 1:2.2-2.7:1.2-1.6, and the ball milling time is 3-5 hours. In step (2), the pressing pressure is 4-6 MPa.

[0011] The present invention utilizes the above-described method for preparing a low-expansion, high-strength, lithium feldspar-cordierite multiphase ceramic green body to obtain a product in which the ceramic green body has a water absorption rate of <0.5%, a flexural strength of 60–70 MPa, and a coefficient of thermal expansion of ≤2.0 × 10⁻⁶ at room temperature to 800°C. -6 / ℃.

[0012] The present invention has the following beneficial effects:

[0013] (1) This invention uses lithium slag, kaolin, boromagnesia, potassium feldspar, and lepidolite as raw materials to construct a Li-K-Mg-B multi-component eutectic system. On the one hand, Li, B, and K in the system are used as strong fluxing components to effectively reduce the liquid phase generation temperature, so that the sintering temperature is reduced to 1180-1200℃, which is significantly lower than the sintering temperature of traditional cordierite or lepidolite ceramics. On the other hand, this multi-component eutectic system can effectively promote the in-situ generation of the target crystal phase. Lithium slag and lepidolite provide Li to react with Si and Al in the liquid phase to generate the lepidolite crystal phase, and boromagnesia provides Mg to react with Si and Al in the liquid phase to generate the cordierite crystal phase, thus constructing a "lepidolite-cordierite" multiphase structure, which has the characteristics of low expansion and high strength.

[0014] (2) This invention uses lithium slag, an industrial solid waste, as the main raw material to prepare high-performance ceramic products, which effectively solves the problems of land occupation and soil pollution caused by lithium slag landfill and realizes the recycling of resources. In addition, the raw materials such as boron magnesium ore and potassium feldspar are widely available and inexpensive, which greatly reduces the production cost. Thus, it has both significant economic and environmental benefits and meets the requirements of green manufacturing and sustainable development strategy. Attached Figure Description

[0015] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings:

[0016] Figure 1 These are SEM images of the ceramic materials obtained in the embodiments of the present invention;

[0017] Figure 2 This is the XRD pattern of the ceramic material obtained in the embodiments of the present invention. Detailed Implementation

[0018] This invention discloses a method for preparing a low-expansion, high-strength ceramic material with a multiphase structure. The raw material composition of the ceramic material is 20-35 wt% lithium slag, 20-30 wt% kaolin, 10-20 wt% boromagnesia, 10-22 wt% potassium feldspar, and 12-20 wt% lepidolite. The preparation method comprises the following steps:

[0019] (1) After mixing the raw materials according to the above composition, place them in a ball mill and ball mill them at a mass ratio of material:ball:water = 1:2.2~2.7:1.2~1.6 for 3~5 hours. Then dry the resulting slurry, pass it through a 150-mesh sieve, and granulate it to obtain the material.

[0020] (2) After pressing the above material into shape under a pressure of 4 to 6 MPa, the temperature is raised from room temperature to 1180 to 1200°C at a heating rate of 2 to 5°C / min, and the holding time is 30 to 60 min. The material is then cooled down with the furnace and naturally cooled to room temperature to obtain a ceramic material with a cordierite-lithite composite structure as the main crystalline phase.

[0021] The raw material composition of each embodiment of the present invention is shown in Table 1; the chemical composition of each raw material is shown in Table 2.

[0022] Table 1 Raw material composition (wt%) of various embodiments of the present invention

[0023]

[0024] Table 2 Chemical composition (wt%) of raw materials used in the embodiments of the present invention

[0025]

[0026] The process parameters for each embodiment of the present invention are shown in Table 3.

[0027] Table 3 Process parameters of various embodiments of the present invention

[0028]

[0029] like Figure 1 As shown, the ceramic body of the present invention clearly contains cordierite and lepidolite crystal phases, which together construct a "lepidolite-cordierite" multiphase structure, giving the present invention the characteristics of low expansion and high strength.

[0030] like Figure 2 As shown, the XRD detection results of this invention are cordierite crystal phase and lepidolite crystal phase, further confirming that the ceramic body has a "lepidolite-cordierite" multiphase structure.

[0031] Comparative Example 1:

[0032] Example 2, which did not contain boron-magnesium ore, was used as Comparative Example 1. The remaining conditions were the same as in Examples 1, 2, 3, and 4, and four sets of experiments were conducted.

[0033] Comparative Example 2:

[0034] Example 2 uses a raw material composition that does not contain lepidolite as Comparative Example 2. The remaining conditions are the same as in Examples 1, 2, 3, and 4, and four sets of experiments are conducted.

[0035] Performance testing:

[0036] The coefficient of thermal expansion was tested according to the test method of GB / T 16535-2008. The flexural strength was tested according to the test method of GB / T 17657-2013. The water absorption rate was tested according to the test method of GB / T 3299-2011. The performance indicators of the ceramic materials obtained by the various embodiments and comparative examples of the present invention are shown in Table 4.

[0037] Table 4 Performance indicators of ceramic materials obtained from the embodiments and comparative examples of the present invention

[0038]

[0039] Remark:

[0040] 1. * indicates room temperature to 800℃.

[0041] 2. The performance index of each comparative example is the average value of the four experimental groups.

Claims

1. A method for preparing a low-expansion, high-strength, lithium-feldspar-cordierite multiphase ceramic green body, characterized in that: The raw material composition of the ceramic body is 20-35 wt% lithium slag, 20-30 wt% kaolin, 10-20 wt% boromagnesia, 10-22 wt% potassium feldspar, and 12-20 wt% lepidolite; the chemical composition of the lithium slag is 82.64-86.12 wt% SiO2, 37.29-11.68 wt% Al2O, 0.07-0.24 wt% K2O, 0.05-0.17 wt% Na2O, 0.72-1.15 wt% Li2O, and 3.45-5.72 wt% Il; the preparation method includes the following steps: (1) After mixing the raw materials according to the above composition, the mixture is placed in a ball mill for ball milling. Then the resulting slurry is dried, sieved, and granulated to obtain the material. (2) After the material is pressed and shaped, it is heated from room temperature to 1180-1200℃ at a rate of 2-5℃ / min, and the holding time is 30-60min. Then, it is cooled down with the furnace and naturally cooled to room temperature to obtain a lithium feldspar-cordierite multiphase ceramic body.

2. The method for preparing a low-expansion, high-strength, lithium-permeable feldspar-cordierite multiphase ceramic green body according to claim 1, characterized in that: In step (1), ball milling is performed at a mass ratio of material:ball:water = 1:2.2-2.7:1.2-1.6, and the ball milling time is 3-5 hours.

3. The method for preparing a low-expansion, high-strength, lithium-feldspar-cordierite multiphase ceramic green body according to claim 1, characterized in that: The pressing pressure in step (2) is 4 to 6 MPa.

4. A lithium feldspar-cordierite multiphase ceramic green body prepared by the method for preparing low-expansion, high-strength lithium feldspar-cordierite multiphase ceramic green body according to any one of claims 1-3, characterized in that: The water absorption rate of the lithium feldspar-cordierite multiphase ceramic green body is <0.5%, the flexural strength is 60-70 MPa, and the coefficient of thermal expansion from room temperature to 800℃ is ≤2.0×10⁻⁶. -6 / ℃.

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