Foamed ceramic and preparation method thereof

Abstract

The invention provides foamed ceramic and a preparation method thereof, and belongs to the technical field of foamed ceramic. The preparation method comprises the following steps: raw material treatment: crushing and mixing the raw materials; granulation: performing granulation on the mixed raw materials; sintering: sintering the granulated particles at high temperature to form a foamed ceramic blank; machining: cutting the foamed ceramic green body by using a machining tool, and cooling and lubricating by using cooling water in the machining process; wherein in the machining step, a lubricating agent is added into the cooling water. The toughness of the foamed ceramic is improved, the lubricating property of the foamed ceramic is improved, and the surface crack rate is reduced.

Description

Technical Field

[0001] This invention relates to the field of foamed ceramics technology, specifically to a foamed ceramic and its preparation method. Background Technology

[0002] Foamed ceramics are a new type of porous ceramic material, mainly made from mine tailings as raw material, with the addition of a certain amount of foaming agent. The process involves batching, ball milling, granulation, spreading, high-temperature firing, and cold working. During firing, the melting of the material matrix is ​​accompanied by the volatilization of the foaming agent gas. When the gas in the melt becomes saturated, the gas trapped in the melt begins to expand. As the firing temperature decreases, the gas cannot break through the high-viscosity melt and remains trapped within it, forming individual closed pores. This results in a foamed ceramic material with high closed-porosity and lightweight properties.

[0003] Ceramic materials are widely used in the construction industry due to their high temperature resistance and good chemical stability. However, the fire resistance of foamed ceramics, as a porous ceramic material, differs significantly from that of traditional ceramics. Cai Yongrong et al. reported that the fire resistance limit of foamed ceramic boards was less than 30 minutes, and that of a 10cm thick foamed ceramic board was just over 20 minutes. Although the types of boards varied, this reflects the need for further research into the fire resistance issues of foamed ceramic boards. If the fire resistance limit of foamed ceramic boards is too low, it will severely limit their application in construction, industrial, and other fields with high fire resistance requirements.

[0004] Fire resistance limit, as a characterization of a material's ability to withstand fire, is a fundamental property of materials and is closely related to the material itself and its processing technology. Therefore, improving the fire resistance limit of foamed ceramics has become an urgent technical problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to improve the fire resistance limit of foamed ceramic materials by increasing their toughness and optimizing cooling and lubrication during machining to reduce microcracks and moisture penetration caused by processing.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A type of foamed ceramic, the raw materials of which comprise the following components by weight percentage: tailings 70-90%, recycled material 5-25%, talc 5-20%, calcium oxide 0-2%, potassium feldspar 0-15%, kaolin 0-12%, bentonite 0-18%, spodumene 0-10%, toughening agent 1.5-10%, dispersant 0.1-1.0%, and foaming agent 0.1-5.0%; The toughening agent is at least one of zirconium oxide powder, zirconium oxide fiber, silicon carbide fiber, silicon nitride fiber, silicon nitride particles, titanium carbide, and titanium oxide.

[0007] Preferably, the foaming agent is at least one of silicon carbide, magnesium oxide, and magnesium carbonate.

[0008] Another technical solution of the present invention is: a method for producing foamed ceramics, comprising the following steps: Raw material processing: The raw materials in the foamed ceramics in the above technical solution are pre-treated by crushing and mixing to ensure the uniformity of the raw materials; Granulation: The mixed raw materials are granulated to form particles with a certain particle size distribution for subsequent firing processes; Firing: The granulated particles are fired at high temperature, which makes the raw material melt and foam at high temperature, forming a foamed ceramic with a certain pore structure, thus forming a foamed ceramic body; Machining: The foamed ceramic blank is cut using tools such as diamond saw blades, metal saw blades, and wire saws, and cooling water is used for cooling and lubrication during the machining process to reduce the generation of cracks; In the machining step, a lubricant is added to the cooling water.

[0009] Preferably, the lubricant is polyethylene glycol with a molecular weight of 200-4000, and the amount added is 5-20% of the total weight of the cooling water.

[0010] Preferably, an antioxidant, namely sulfolane, is added to the cooling water at a concentration of 0.2-2.0% of the total weight of the cooling water.

[0011] Compared with the prior art, the present invention achieves the following technical effects: This invention significantly improves the toughness of the material itself. This allows the foamed ceramic to better resist stress during subsequent machining processes (such as cutting and sawing), thereby greatly reducing surface and internal microcracks caused by processing. The reduction of microcracks directly reduces the channels for moisture intrusion, and the pressure generated by the rapid vaporization of moisture at high temperatures is one of the key factors leading to a decrease in the material's refractoriness.

[0012] In the machining process, the addition of lubricant and antioxidant to the cooling water significantly improves the cooling and lubrication effect. This improvement further reduces mechanical damage to the material surface from machining tools and minimizes the formation of new microcracks. Ultimately, the foamed ceramic products prepared by this invention not only have higher toughness but, more importantly, lower surface crack rate and water absorption, resulting in superior structural stability and a longer fire resistance limit when exposed to fire. Detailed Implementation

[0013] The following are specific embodiments of the present invention, which further describe the technical solutions of the present invention. However, the present invention is not limited to these embodiments. In the following description, specific details such as specific configurations are provided merely to help to fully understand the embodiments of the present invention. Therefore, those skilled in the art should understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention.

[0014] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0015] Unless otherwise specified, the materials, practices, and experimental equipment involved in the embodiments of this invention are all commercially available products in the relevant chemical and biotechnology fields.

[0016] This invention provides a foamed ceramic, the raw materials of which include the following components by weight percentage: 70-90% tailings, 5-25% recycled material, 5-20% talc, 0-2% calcium oxide, 0-15% potassium feldspar, 0-12% kaolin, 0-18% bentonite, 0-10% spodumene, 1.5-10% toughening agent, 0.1-1.0% dispersant, and 0.1-5.0% foaming agent. The preparation method includes pretreatment of raw materials by crushing and mixing to ensure uniformity; granulation of the mixed raw materials to form particles with a certain particle size distribution for subsequent firing processes; high-temperature firing of the granulated particles to melt and foam the raw materials at high temperature, forming a foamed ceramic with a certain porous structure, i.e., a foamed ceramic green body; cutting and processing the foamed ceramic green body using tools such as diamond saw blades, metal saw blades, and wire saws, with cooling water used for cooling and lubrication during processing to reduce cracking; wherein, in the machining step, a lubricant is added to the cooling water. The lubricant is polyethylene glycol with a molecular weight of 200-4000, and the amount added is 5-20% of the total weight of the cooling water. An antioxidant, sulfolane, is also added to the cooling water, and the amount added is 0.2-2.0% of the total weight of the cooling water.

[0017] Table 1. Firing process parameters for foamed ceramics

[0018] Example 1 Raw material ratio (by weight percentage): Tailings: 80% Recycled materials: 8% Talc: 8% Zirconia powder (as toughening agent): 3% Silicon carbide (as a blowing agent): 0.8% Dispersant (sodium tripolyphosphate): 0.2% Preparation method: Raw material processing and granulation: All the above raw materials are placed in a ball mill and mixed evenly, and water is added for wet ball milling until the fineness of the slurry meets the requirements. Then the slurry is spray-granulated to obtain a powder with uniform particle size.

[0019] Firing: The granulated powder is placed in a refractory mold and sent into a high-temperature kiln. It is heated according to the heating program set in Table 1 to melt and foam the raw material, and then naturally cooled to room temperature to obtain a foamed ceramic body.

[0020] Machining: The foamed ceramic blank is cut using a diamond saw blade. Cooling and lubrication are achieved using cooling water. This cooling water is an aqueous solution containing 15% polyethylene glycol with a molecular weight of 400 and 0.5% sulfolane (as an antioxidant).

[0021] Packaging: The cut foamed ceramic slabs are cleaned, dried, and then packaged.

[0022] Example 2 Raw material ratio (by weight percentage): Tailings: 75% Recycled materials: 10% Talc: 10% Potassium feldspar: 2% Silicon carbide fiber (as toughening agent): 2.5% Magnesium carbonate (as a foaming agent): 0.4% Dispersant (sodium silicate): 0.1% Preparation method: Raw material processing and granulation: Similar to the steps in Example 1, the raw materials are mixed, ball-milled, and granulated.

[0023] Firing: After the material is laid out, it is heated according to the heating program set in Table 1 to carry out firing.

[0024] Machining: Cutting is performed using a wire saw. The cooling water is an aqueous solution containing 8% polyethylene glycol with a molecular weight of 2000 and 1.0% sulfolane.

[0025] Packaging: Same as in Example 1.

[0026] Example 3 Raw material ratio (by weight percentage): Tailings: 85% Recycled materials: 5% Talc: 5% Kaolin: 2% Silicon nitride particles (as toughening agent): 2.0% Magnesium oxide (as a foaming agent): 0.9% Dispersant (sodium hexametaphosphate): 0.1% Preparation method: Raw material processing and granulation: Similar to the steps in Example 1.

[0027] Firing: After the material is laid out, it is heated according to the heating program set in Table 1 to carry out firing.

[0028] Machining: Cutting is performed using a metal saw blade. The cooling water is an aqueous solution containing 20% ​​polyethylene glycol with a molecular weight of 600 and 0.2% sulfolane.

[0029] Packaging: Same as in Example 1.

[0030] Comparative Example Raw material ratio: The matrix formulation is similar to that of Example 1, but no toughening agent is added.

[0031] Preparation method: The raw material processing, granulation, and calcination steps are exactly the same as in Example 1. However, during machining and cutting, only ordinary tap water is used as the coolant, and no lubricant or antioxidant is added.

[0032] Table 2 Performance Tests

[0033] Those skilled in the art to which this application pertains may modify or supplement the specific embodiments described or use similar methods to replace them, but without departing from the inventive concept of this application or exceeding the scope defined by the appended claims.

Claims

1. A foamed ceramic, characterized by, The raw materials include the following components by weight percentage: Tailings 70-90%, Recycled material 5-25%, Talc 5-20%, Calcium oxide 0-2%, Potassium feldspar 0-15%, Kaolin 0-12%, Bentonite 0-18%, Spodumene 0-10%, Toughening agent 1.5-10%, Dispersing agent 0.1-1.0%, Foaming agent 0.1-5.0%; The toughening agent is at least one of zirconium oxide powder, zirconium oxide fiber, silicon carbide fiber, silicon nitride fiber, silicon nitride particles, titanium carbide, titanium oxide.

2. The foamed ceramic of claim 1, wherein, The foaming agent is at least one of silicon carbide, magnesium oxide, magnesium carbonate.

3. A method for producing a foamed ceramic, characterized by, The method includes the following steps: Raw material processing: crushing and mixing the raw materials; Granulation: granulating the mixed raw materials; Sintering: sintering the granulated particles at high temperature to form a foamed ceramic body; Machining: cutting the foamed ceramic body using a machining tool and using cooling water for cooling and lubrication during machining; The cooling water in the machining step is added with a lubricant.

4. The production method according to claim 3, characterized by, The lubricant is polyethylene glycol with a molecular weight of 200-4000 and an addition amount of 5-20% of the total weight of the cooling water.

5. The production method according to claim 4, characterized by, The cooling water is also added with an antioxidant.

6. The production method according to claim 5, characterized by, The antioxidant is sulfolane with an addition amount of 0.2-2.0% of the total weight of the cooling water.

7. The production method according to any one of claims 3 to 6, characterized by, The raw materials include the following components by weight percentage: Tailings 70-90%, Recycled material 5-25%, Talc 5-20%, Calcium oxide 0-2%, Potassium feldspar 0-15%, Kaolin 0-12%, Bentonite 0-18%, Spodumene 0-10%, Toughening agent 1.5-10%, Dispersing agent 0.1-1.0%, Foaming agent 0.1-5.0%.

8. The production method according to claim 7, characterized by, The toughening agent is at least one of zirconium oxide powder, zirconium oxide fiber, silicon carbide fiber, silicon nitride fiber, silicon nitride particles, titanium carbide, titanium oxide.

9. The production method according to claim 7, characterized by, The foaming agent is at least one of silicon carbide, magnesium oxide, magnesium carbonate.

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