Production process of porous ceramic filter for liquid alloy

Abstract

The invention relates to a production process of a porous ceramic filter for a liquid alloy. The production process comprises the following steps: (1) mixing ceramic micro powder and a liquid binding agent according to a certain proportion to prepare ceramic slurry; (2) weighing the ceramic particles and the ceramic slurry according to a certain weight ratio, uniformly mixing the ceramic particles and the ceramic slurry, and pouring a mixture of the mixed ceramic particles and the slurry into a forming mold; (3) the mold is placed on a vibration table for vibration forming, and the formed mold is placed in a drying oven to be heated, dried and cured; (4) removing the mold to obtain a formed green body, and repairing the green body to a certain degree to enable the size of the green body to meet the requirement; and (5) sintering the green body under a high-temperature condition to obtain a finished product. The method has the advantages of simple and efficient preparation process, low cost, green and pollution-free production process and the like, and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramic filter preparation, and in particular relates to a production process of a porous ceramic filter for liquid alloy. Background Art

[0002] Porous ceramics are a type of material with a three-dimensional network skeleton structure and a large number of pores inside. They have a series of advantages such as high temperature resistance, high mechanical strength and large specific surface area. They are widely used in many fields such as thermal insulation, sound absorption and filtering, and liquid filtration. Foam ceramics prepared by the organic foam impregnation method are representatives of the third generation of porous ceramics. Because of their high porosity, wider pore size distribution and the advantages of ceramics themselves, they are widely used in many fields such as metal smelting, aerospace and medical chemical industry.

[0003] However, there are many problems with the current organic foam impregnation method: 1. The wettability between the organic foam and the ceramic slurry is poor, which seriously affects the thickness and uniformity of the ceramic slurry; 2. The organic foam will deform during burnout, and the hollow structure formed after burnout greatly reduces the mechanical properties of the material; 3. The organic foam will produce toxic and harmful gases during the burnout process, causing serious pollution to the environment; therefore, developing a template-free method to prepare porous ceramic filters for liquid materials is the future development direction of porous ceramic filters. Summary of the Invention

[0004] In view of the defects of the existing organic foam impregnation method in preparing porous ceramic filters, the purpose of the present invention is to provide a production process for porous ceramic filters for liquid alloys.

[0005] The present invention adopts the following technical solutions to achieve the above-mentioned purpose: A production process for a porous ceramic filter for liquid alloys. The production process of the porous ceramic filter adopts a particle stacking method to prepare porous ceramics. Fine powders of the same composition are added to the ceramic aggregate, the two are uniformly mixed, and then formed, dried and solidified. Finally, the finished product is sintered under high temperature conditions. The production process specifically includes the following steps: The ceramic powder and the liquid binder are mixed in a blender at a mass ratio of 1:1 to prepare a ceramic slurry; the ceramic powder component is one of aluminum oxide, silicon oxide, zirconium oxide, mullite or silicon carbide; The ceramic particles and the ceramic slurry are uniformly mixed in a weight ratio of 10:1 to 10:2, and the mixed ceramic particles and slurry mixture is poured into a forming mold; the ceramic particles are composed of one of aluminum oxide, silicon oxide, zirconium oxide, mullite or silicon carbide; (3) placing the mold containing the ceramic particles and slurry on a vibration table for vibration molding, and placing the molded mold in an oven for dehydration and curing; (4) Remove the mold to obtain the formed green body and perform some repairs on the green body to make the green body size meet the requirements; (5) Sintering the green body at high temperature to obtain the finished product.

[0006] The particle size of the ceramic micropowder is 325 meshes.

[0007] The liquid binder is PVA, PVB, silica sol or aluminum sol.

[0008] The particle size of the ceramic particles is a single size particle size within the range of 0.5-5 mm, the particle size of the small-pore filter is 0.5-1 mm sand-like particles, and the particle size of the large-pore filter is 4-5 mm ceramic particles.

[0009] The weight ratio of the ceramic particles to the ceramic slurry of the large-pore filter is selected to be 10:1, and the weight ratio of the ceramic particles to the ceramic slurry of the small-pore particle filter is selected to be 10:2.

[0010] The mixing method is stirring mixing, and the mixing time is greater than 30 minutes.

[0011] The vibration table is a common vibration table, and the vibration time is 1 to 3 minutes.

[0012] The dehydration and solidification temperature is 60° C., and the heat preservation time is 12 to 24 hours. The heat preservation time of the large-pore filter is preferably 12 hours, and the heat preservation time of the small-pore filter is preferably 24 hours.

[0013] The sintering temperature is 1400-1600°C and the holding time is 2-5 hours. Among them, products made of materials such as mullite and brown corundum are sintered at a low temperature of 1400℃, products made of zirconia and alumina are sintered at a high temperature of 1600℃, and silicon carbide products are sintered in a vacuum.

[0014] The present invention proposes a production process for porous ceramic filters for liquid alloys, which adopts a particle accumulation method to prepare porous ceramics. Fine powder of the same composition is added to the ceramic aggregate, the two are evenly mixed, and solidified through molding and drying, and finally sintered under high temperature conditions to obtain the finished product. Compared with the ceramic filters prepared by the traditional organic foam impregnation method, this method effectively avoids the emission of harmful gases during the high-temperature burnout process. At the same time, since the filter is formed by sintering the accumulation of particles, the filter has higher strength and better anti-scouring performance, which can well solve the problems of harmful waste gas emissions during the high-temperature burnout template of the current organic foam impregnation method, low filter strength, poor thermal shock stability and poor anti-scouring ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1Schematic diagram of a large-pore ceramic particle filter prepared using 4-5 mm alumina ceramic particles; Figure 2 Schematic diagram of a small-pore size ceramic particle filter made from 0.5-1 mm zirconia ceramic particles. DETAILED DESCRIPTION

[0016] like Figure 1 、 Figure 2 As shown, the specific embodiments of the present invention will be described in detail below; however, the present invention can be implemented in various forms and is not limited to the specific embodiments described herein. The present invention will be further described in conjunction with the examples, and the raw materials used in the present invention were directly purchased.

[0017] The porous ceramic filter for liquid alloy in this embodiment is prepared by the following method: ① Add ceramic powder and liquid binder in a weight ratio of 1:1 into a container and mix them evenly with a blender to obtain ceramic slurry; ② Mix one of the following ceramic particles, selected from alumina, silica, zirconia, mullite, and silicon carbide, in a specific weight ratio with the ceramic slurry prepared in step 1 in a blender for at least 30 minutes. Pour the resulting mixture of ceramic particles and slurry into a mold. ③ Place the mold containing ceramic particles and slurry in step ② on a vibration table for vibration molding. The molded mold is placed in a 60°C oven for dehydration and curing; ④ Remove the mold after dehydration and curing in step ③ to obtain the formed green body and perform some repairs on the green body to make the green body size meet the requirements; ⑤ Place the trimmed green body into a high-temperature furnace and sinter it to obtain the finished product. Example

[0018] ① Add 325 mesh silicon carbide powder and PVA aqueous solution in a weight ratio of 1:1 into a container and mix them evenly with a blender to obtain a uniform and stable ceramic slurry; ② Weigh 1.5mm silicon carbide particles and the ceramic slurry prepared in step 1 at a weight ratio of 10:1 and mix in a blender for 30 minutes. Then, pour the mixture of ceramic particles and slurry into a tubular mold. ③ Place the mold containing ceramic particles and slurry in step ② on a vibration table for vibration molding. The molded mold is placed in a 60°C oven for dehydration and curing; ④ Remove the mold after dehydration and curing in step ③ to obtain the formed green body and perform some repairs on the green body to make the green body size meet the requirements; ⑤ Place the trimmed green body into a vacuum furnace and sinter it at a temperature of 2200°C for 5 hours to obtain the finished product. Example

[0019] ① Add 325-mesh alumina powder and PVA aqueous solution into a container at a weight ratio of 1:1 and mix them evenly with a stirrer to obtain a uniform and stable ceramic slurry; ② Weigh 5mm plate-shaped alumina particles and the ceramic slurry prepared in step 1 at a weight ratio of 10:1 and mix in a blender for 30 minutes. Then, pour the mixture of ceramic particles and slurry into a tubular mold. ③ Place the mold containing ceramic particles and slurry in step ② on a vibration table for vibration molding. The molded mold is placed in a 60°C oven for dehydration and curing; ④ Remove the mold after dehydration and curing in step ③ to obtain the formed green body and perform some repairs on the green body to make the green body size meet the requirements; ⑤ Place the trimmed green body into a high-temperature furnace for sintering at a temperature of 1600°C for 5 hours to obtain the finished product. Example

[0020] ① Add 325-mesh zirconium oxide powder and PVA aqueous solution into a container at a weight ratio of 1:1, and mix them evenly with a stirrer to obtain a uniform and stable ceramic slurry; ② Weigh 0.5mm zirconia particles and the ceramic slurry prepared in step 1 at a weight ratio of 10:2 and mix in a blender for 30 minutes. Then, pour the mixture of ceramic particles and slurry into a circular mold. ③ Place the mold containing ceramic particles and slurry in step ② on a vibration table for vibration molding. The molded mold is placed in a 60°C oven for dehydration and curing; ④ Remove the mold after dehydration and curing in step ③ to obtain the formed green body and perform some repairs on the green body to make the green body size meet the requirements; ⑤ Place the trimmed green body into a high-temperature furnace for sintering at a temperature of 1600°C for 5 hours to obtain the finished product.

Claims

1. A production process for a porous ceramic filter for liquid alloy, characterized in that The production process of porous ceramic filters adopts the particle stacking method to prepare porous ceramics, adding fine powder of the same composition to the ceramic aggregate, mixing the two evenly and solidifying them by molding and drying, and finally sintering them under high temperature conditions to obtain the finished product, which specifically includes the following steps: (1) mixing ceramic powder and liquid binder in a mixer at a mass ratio of 1:1 to prepare a ceramic slurry; the ceramic powder component is one of aluminum oxide, silicon oxide, zirconium oxide, mullite or silicon carbide; (2) uniformly mixing ceramic particles and ceramic slurry at a weight ratio of 10:1 to 10:2, and pouring the mixed ceramic particles and slurry mixture into a molding mold; the ceramic particles are composed of one of aluminum oxide, silicon oxide, zirconium oxide, mullite or silicon carbide; (3) placing the mold containing the ceramic particles and the slurry on a vibration table for vibration molding, and placing the mold after molding in an oven for dehydration and curing; (4) Remove the mold to obtain the formed green body and perform some repairs on the green body to make the green body size meet the requirements; (5) Sintering the green body under high temperature conditions to obtain the finished product.

2. The production process of a porous ceramic filter for liquid alloy according to claim 1, characterized in that: The particle size of the ceramic micropowder is 325 meshes.

3. The production process of a ceramic filter for liquid metal alloy according to claim 1, characterized in that: The liquid binder is PVA, PVB, silica sol and aluminum sol.

4. The production process of a porous ceramic filter for liquid alloy according to claim 1, characterized in that: The particle size of the ceramic particles is a single size particle size within the range of 0.5 to 5 mm.

5. The production process of a porous ceramic filter for liquid alloy according to claim 1, characterized in that: The ceramic particles and the ceramic slurry are mixed by stirring.

6. The production process of a porous ceramic filter for liquid alloy according to claim 1, characterized in that: The vibration table is a common vibration table, and the vibration time is 1 to 3 minutes.

7. The production process of a porous ceramic filter for liquid alloy according to claim 1, characterized in that: The dehydration and curing temperature is 60° C., and the heat preservation time is 24 hours.

8. The production process of a porous ceramic filter for liquid alloy according to claim 1, characterized in that: The sintering temperature is between 1400 and 1600° C., and the heat preservation time is between 2 and 5 hours.

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