A black alumina porous ceramic material for vacuum suction cups and its preparation method

Abstract

The application relates to the technical field of alumina ceramics, and discloses a black alumina porous ceramic material for a vacuum suction cup and a preparation method of the black alumina porous ceramic material, which selects the types and the proportion of a colorant, the types and the amount of a pore-forming agent, prepares the black alumina porous ceramic with excellent performance of traditional ceramic materials, and provides a more reliable solution for the production of high-precision semiconductor components, and has important significance for promoting the sustainable development of the semiconductor industry in China.

Description

Technical Field

[0001] This invention relates to the field of alumina ceramics technology, and in particular to a black porous alumina ceramic material for vacuum suction cups and its preparation method. Background Technology

[0002] With the development of domestic technology, various electronic information components are gradually becoming more refined and lightweight, leading to an increasing demand for thin-film products. However, the process of transferring these materials relies heavily on vacuum chucks. Traditional vacuum chucks are mostly made of metal materials using surface perforation. These chucks have relatively large apertures, generating greater suction force. When processing small workpieces, this can easily cause deformation, and in severe cases, even breakage. Using ceramic vacuum chucks, it is possible to create uniformly distributed openings with a aperture of <100μm. This new type of vacuum chuck is beneficial for accelerating the independent development of my country's semiconductor equipment industry.

[0003] Furthermore, high-precision semiconductor components, especially photosensitive semiconductor components, are extremely sensitive to ambient light during production and handling. Any accidental light exposure can cause irreversible damage to the performance of photosensitive semiconductor components, thereby affecting the quality and reliability of the entire product. Against this backdrop, black alumina porous ceramics stand out due to their superior light-shielding capabilities, becoming an ideal material for handling such sensitive components. Black alumina porous ceramics can effectively block ambient light, ensuring that photosensitive semiconductor components are protected from light interference during processing, thus preserving their photoelectric properties. Particularly in the production of ultraviolet-sensitive semiconductor devices, handling arms made of black alumina porous ceramics can effectively block ultraviolet radiation, preventing performance degradation due to photoinduced effects and further improving the stability and reliability of the production process. However, the preparation process of the black alumina porous ceramics described in patent CN117585990A is relatively complex, and the color cannot be made pure black; moreover, the internal and external colors are inconsistent, significantly reducing the ability to effectively block ambient light and making industrial production difficult. Summary of the Invention

[0004] To address the technical problems mentioned in the background art, such as insufficient color purity, inconsistent internal and external colors, and high difficulty in industrial production, this invention provides a black alumina porous ceramic material for vacuum suction cups and its preparation method. The prepared porous ceramic has uniform color, high compressive strength, high apparent porosity, and high flexural strength. Moreover, the material preparation process is simple and easy to realize industrial production.

[0005] The specific technical solution of this invention is: a method for preparing a black alumina porous ceramic material for vacuum suction cups, comprising the following steps:

[0006] 1) Mix 4-5 parts by weight of alumina micro powder, 10-11 parts by weight of silica micro powder, 7-8 parts by weight of colorant and 20-25 parts by weight of water, then add 0.5-1 parts by weight of polyacrylic acid, 6-8 parts by weight of N-hydroxymethylacrylamide and N,N'-methylenebisacrylamide, and ball mill for 30-60 minutes.

[0007] 2) Add 35-40 parts of white corundum coarse powder, 30-35 parts of pore-forming agent and 35-38 parts of suspending agent, centrifuge and stir for 2-3 minutes, repeat 3-5 times;

[0008] 3) Add 1 to 1.5 parts of ammonium persulfate, stir well, pour into a mold, and let stand at 60 to 65°C for 30 to 45 minutes;

[0009] 4) After demolding and drying, degreasing and sintering are carried out to obtain black alumina porous ceramic material for vacuum suction cups.

[0010] This invention uses iron oxide, chromium trioxide, cobalt trioxide, and nickel oxide as colorants. The research team conducted numerous creative experiments and determined that adjusting the colorant composition ratio to iron oxide micropowder: chromium trioxide: cobalt trioxide: nickel oxide = (2.8–3.2): (1.8–2.2): (1.3–1.5): (0.4–0.6) results in a uniform black color throughout the alumina after sintering. The smaller particle size of silica micropowder is considered a sintering aid, readily forming a liquid phase on the surface of the white corundum framework. Polyacrylic acid is used as a dispersant to disperse the alumina micropowder, silica micropowder, and colorant to form a uniform porous ceramic material. N-hydroxymethylacrylamide is used as an organic monomer, and N,N'-methylenebisacrylamide as a crosslinking agent. The material is injection molded using an aqueous gel injection molding system, expanding its application range to the manufacture of components with complex shapes and high precision requirements.

[0011] Further, in step 1), the colorant is iron oxide micro powder, chromium trioxide, cobalt trioxide and nickel oxide in a weight ratio of (2.8-3.2):(1.8-2.2):(1.3-1.5):(0.4-0.6).

[0012] Further, in step 1), the particle size of the alumina micro powder is: D 10 =0.3~0.35μm; D 50 =0.5~0.55μm; D 90 =3~3.1μm.

[0013] Further, in step 1), the particle size of the silica micro powder is: D 10 =0.8~0.85μm; D 50 =1~1.05μm; D 90 =5~5.2μm.

[0014] Further, in step 2), the coarse white fused alumina powder is fused white fused alumina with a particle size of: D 10 =10~11μm; D 50 =15~16μm; D 90 =25~26μm.

[0015] Further, in step 2), the pore-forming agent is one or more of polymethyl methacrylate, spherical graphite, and industrial starch, with a particle size of: D. 10 =30~40μm; D 50 =45~55μm; D 90 =55~70μm, the pore-forming agent will burn and be expelled in gaseous form during the degreasing process, leaving pores in situ. This method combines sintering and template methods to obtain porous ceramics with high apparent porosity.

[0016] Furthermore, in step 2), the suspending agent is one or more of polyvinyl alcohol and polyethylene oxide aqueous solutions with a concentration of 5-6 wt%. The use of the suspending agent can prevent the rapid sedimentation of the white corundum coarse powder.

[0017] As a preferred method, centrifugal mixing uses an industrial-grade rotary centrifugal mixer to quickly mix all the slurry. This method can degas the slurry while mixing, significantly improve the dispersibility of high-viscosity slurries, and further prevent the sedimentation of white fused alumina during slurry solidification.

[0018] Further, in step 4), the drying process is as follows: after drying at 40-45℃ and 80-85% relative humidity for 24-30 hours, drying at 60-65℃ and 40-45% relative humidity for 24-30 hours, and finally drying at 80-85℃ and 20-25% relative humidity for 24-30 hours.

[0019] Further, in step 4), the degreasing and sintering temperature is 1400–1450℃, and the degreasing and sintering time is 2–3 hours.

[0020] Furthermore, a black alumina porous ceramic material for vacuum chucks is prepared according to the above-mentioned method for preparing black alumina porous ceramic material for vacuum chucks.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1) The porous alumina ceramic prepared by this invention has a porosity of 30-40%, uniform pore size distribution, and a bending strength of ≥100 MPa, which is a significant improvement over traditional porous alumina ceramics. It is suitable for porous alumina ceramic vacuum chucks in the semiconductor industry.

[0023] 2) The selection of colorant types and ratios can produce black alumina porous ceramics with uniform color inside and out, thus broadening the application fields of the material.

[0024] 3) Rough processing of ceramic blanks can reduce the cost of fine processing after sintering, simplify the process flow, facilitate industrial production, improve production safety, and at the same time reduce production costs and environmental pollution. Attached Figure Description

[0025] Figure 1 The image shows the SEM morphology of the porous ceramic prepared in Example 1. Detailed Implementation

[0026] The present invention will be further described below with reference to embodiments.

[0027] Unless otherwise specified, all raw materials used in this invention are commercially available or commonly used in the field. Unless otherwise specified, the methods in the following embodiments are conventional methods in the field.

[0028] Example 1

[0029] A black alumina porous ceramic material for vacuum suction cups is prepared by the following method:

[0030] 1) Preparation of slurry

[0031] By weight, 42 parts of particle size D 10 =0.3μm, D 50 =0.5μm, D 90 =3μm alumina micro powder, 11 parts with a particle size of D 10 =0.8μm, D 50 =1μm, D 90 =5μm silica micro powder, 3 parts iron oxide micro powder, 2 parts chromium trioxide, 1.5 parts cobalt trioxide, 0.5 parts nickel oxide and 24 parts deionized water were mixed. Then 1.5 parts polyacrylic acid, 7 parts N-hydroxymethylacrylic acid and 0.5 parts N,N'-methylenebisacrylamide were added. The mixture was ball-milled for 60 minutes until the powder was uniform. Then 38 parts coarse white corundum powder, 30 parts polymethyl methacrylate microspheres and 36 parts polyvinyl alcohol aqueous solution with a mass concentration of 5% were added. The mixture was poured into a rotary mixer and mixed at 2100 rpm for 2 minutes. The mixture was repeated three times to obtain a uniformly mixed porous ceramic slurry.

[0032] 2) Injection molding: Add 1 part of ammonium persulfate to the uniformly mixed porous ceramic slurry obtained in step 1), pour it into the mold, and place it in a water bath at a water temperature of 60°C for 30 minutes to wait for molding.

[0033] 3) Post-processing of materials

[0034] The shaped ceramic material prepared in step 2) was dried in a constant temperature and humidity chamber at 25°C and 80% relative humidity for 12 hours, at 40°C and 60% relative humidity for 12 hours, and at 80°C and 20% relative humidity for 24 hours. It was then degreased and sintered in an atmospheric atmosphere sintering furnace at a maximum sintering temperature of 1350°C for 2 hours to produce porous ceramic material.

[0035] 4) Performance Testing

[0036] The density, flexural strength, and apparent porosity of the porous ceramic material prepared in step 3) were tested, and the color of the porous ceramic material was recorded. The porosity was tested according to GB / T25995-2010, and the flexural strength was tested according to GBT_6569-2006.

[0037] Figure 1 It clearly exhibits a skeletal morphology composed of white fused alumina, with obvious traces of an active alumina matrix and a liquid silica phase covering its surface. The white fused alumina particles are interconnected, forming a dense skeletal structure that greatly enhances the material's mechanical strength. Furthermore, most of the visible pores are uniformly sized and distributed, with a distinct layered structure.

[0038] XRD analysis revealed that the colorant, alumina, and sintering aids reacted to form various spinel compounds, such as Cr. 1.6 NiAl 0.4 O4, Cr 1.7 Fe 0.3 O3. When iron oxide, chromium trioxide, cobalt trioxide, and nickel oxide react fully with each other, a black color is produced. If one of the colorants is in excess, it will lead to incomplete reaction, causing color deviation. For example, in Comparative Examples 1 and 2, an excess of chromium trioxide results in a green color, while an excess of iron oxide results in a red color. Only a black color can provide a beneficial effect when handling semiconductor components.

[0039] Comparative Example 1

[0040] The only difference between this comparative example and Example 1 is that in this comparative example, 2 parts of iron oxide micro powder and 3 parts of chromium trioxide colorant are added in step 1), thus changing the ratio of colorants. The rest of the process is the same as in Example 1. The specific steps are as follows:

[0041] 1) Preparation of slurry

[0042] By weight, 42 parts of particle size D 10 =0.3μm, D 50 =0.5μm, D 90 =3μm alumina micro powder, 11 parts with a particle size of D 10 =0.8μm, D50 =1μm, D 90 =5μm silica micro powder, 2 parts iron oxide micro powder, 3 parts chromium trioxide, 1.5 parts cobalt trioxide, 0.5 parts nickel oxide and 24 parts deionized water were mixed. Then 1.5 parts polyacrylic acid, 7 parts N-hydroxymethylacrylic acid and 0.5 parts N,N'-methylenebisacrylamide were added. The mixture was ball-milled for 60 minutes until the powder was uniform. Then 38 parts coarse white corundum powder, 30 parts polymethyl methacrylate microspheres and 36 parts polyvinyl alcohol aqueous solution with a mass concentration of 5% were added. The mixture was poured into a rotary mixer and mixed at 2100 rpm for 2 minutes. The mixture was repeated three times to obtain a uniformly mixed porous ceramic slurry.

[0043] 2) Injection molding: Add 1 part of ammonium persulfate to the uniformly mixed porous ceramic slurry obtained in step 1), pour it into the mold, and place it in a water bath at a water temperature of 60°C for 30 minutes to wait for molding.

[0044] 3) Post-processing of materials

[0045] The shaped ceramic material prepared in step 2) was dried in a constant temperature and humidity chamber at 25°C and 80% relative humidity for 12 hours, at 40°C and 60% relative humidity for 12 hours, and at 80°C and 20% relative humidity for 24 hours. It was then degreased and sintered in an atmospheric atmosphere sintering furnace at a maximum sintering temperature of 1350°C for 2 hours to produce porous ceramic material.

[0046] 4) Performance Testing

[0047] The density, flexural strength, and apparent porosity of the porous ceramic material prepared in step 3) were tested, and the color of the porous ceramic material was recorded. The porosity was tested according to GB / T25995-2010, and the flexural strength was tested according to GBT_6569-2006.

[0048] Comparative Example 2

[0049] The only difference between this comparative example and Example 1 is that in this comparative example, 4 parts of iron oxide micro powder and 1 part of chromium trioxide colorant are added in step 1), thus changing the ratio of colorants. The rest of the process is the same as in Example 1. The specific steps are as follows:

[0050] 1) Preparation of slurry

[0051] By weight, 42 parts of particle size D 10 =0.3μm, D 50 =0.5μm, D 90 =3μm alumina micro powder, 11 parts with a particle size of D 10 =0.8μm, D 50 =1μm, D 90=5μm silica micro powder, 4 parts iron oxide micro powder, 1 part chromium trioxide, 1.5 parts cobalt trioxide, 0.5 parts nickel oxide and 24 parts deionized water were mixed. Then 1.5 parts polyacrylic acid, 7 parts N-hydroxymethylacrylic acid and 0.5 parts N,N'-methylenebisacrylamide were added. The mixture was ball-milled for 60 minutes until the powder was uniform. Then 38 parts coarse white corundum powder, 30 parts polymethyl methacrylate microspheres and 36 parts polyvinyl alcohol aqueous solution with a mass concentration of 5% were added. The mixture was poured into a rotary mixer and mixed at 2100 rpm for 2 minutes. The mixture was repeated three times to obtain a uniformly mixed porous ceramic slurry.

[0052] 2) Injection molding: Add 1 part of ammonium persulfate to the uniformly mixed porous ceramic slurry obtained in step 1), pour it into the mold, and place it in a water bath at a water temperature of 60°C for 30 minutes to wait for molding.

[0053] 3) Post-processing of materials

[0054] The shaped ceramic material prepared in step 2) was dried in a constant temperature and humidity chamber at 25°C and 80% relative humidity for 12 hours, at 40°C and 60% relative humidity for 12 hours, and at 80°C and 20% relative humidity for 24 hours. It was then degreased and sintered in an atmospheric atmosphere sintering furnace at a maximum sintering temperature of 1350°C for 2 hours to produce porous ceramic material.

[0055] 4) Performance Testing

[0056] The density, flexural strength, and apparent porosity of the porous ceramic material prepared in step 3) were tested, and the color of the porous ceramic material was recorded. The porosity was tested according to GB / T25995-2010, and the flexural strength was tested according to GBT_6569-2006.

[0057] Table 1. Effect of colorant ratio on the properties of the final porous ceramic.

[0058]

[0059] The data in Table 1 shows that changing the colorant ratio, i.e., excessively high iron oxide or cobalt trioxide content, will alter the color of the final porous ceramic. However, it has little impact on other properties of the porous ceramic, such as apparent porosity, density, and flexural strength. This is presumably because the main properties of the porous ceramic in this patent are determined by the main material, white corundum, and its porosity. The difference between Comparative Example 1 and Comparative Example 2 is that one added more chromium trioxide, and the other added more iron oxide. Comparing these two materials, iron oxide is not only an excellent colorant but also a highly efficient one. Sintering aids result in a deeper sintering of alumina, leading to a slight increase in flexural strength and a slight decrease in apparent porosity. Overall, the impact is minor, but the effect on color is significant, failing to meet the requirements of this material. Chromium trioxide, primarily used as a colorant, has no obvious sintering aid effect. Therefore, adding more chromium trioxide not only alters the color but also reduces apparent porosity, density, and flexural strength, while increasing closed porosity. In conclusion, excessive addition of any single colorant does not produce beneficial effects on the target product; the most suitable ratio must be found.

[0060] Comparative Example 3

[0061] The only difference between this comparative example and Example 1 is that in this comparative example, 15 parts of the pore-forming agent polymethyl methacrylate microspheres are added in step 1), thus changing the ratio of the pore-forming agent. The rest of the process is the same as in Example 1. The specific steps are as follows:

[0062] 1) Preparation of slurry

[0063] By weight, 42 parts of particle size D 10 =0.3μm, D 50 =0.5μm, D 90 =3μm alumina micro powder, 11 parts with a particle size of D 10 =0.8μm, D 50 =1μm, D 90 =5μm silica micro powder, 3 parts iron oxide micro powder, 2 parts chromium trioxide, 1.5 parts cobalt trioxide, 0.5 parts nickel oxide and 24 parts deionized water were mixed. Then 1.5 parts polyacrylic acid, 7 parts N-hydroxymethylacrylic acid and 0.5 parts N,N'-methylenebisacrylamide were added. The mixture was ball-milled for 60 minutes until the powder was uniform. Then 38 parts coarse white corundum powder, 15 parts polymethyl methacrylate microspheres and 36 parts polyvinyl alcohol aqueous solution with a mass concentration of 5% were added. The mixture was poured into a rotary mixer and mixed at 2100 rpm for 2 minutes. The mixture was repeated three times to obtain a uniformly mixed porous ceramic slurry.

[0064] 2) Injection molding

[0065] Add 1 part of ammonium persulfate to the uniformly mixed porous ceramic slurry obtained in step 1), pour it into a mold, and place it in a water bath at a water temperature of 60°C for 30 minutes to allow it to solidify.

[0066] 3) Post-processing of materials

[0067] The shaped ceramic material prepared in step 2) was dried in a constant temperature and humidity chamber at 25°C and 80% relative humidity for 12 hours, at 40°C and 60% relative humidity for 12 hours, and at 80°C and 20% relative humidity for 24 hours. It was then degreased and sintered in an atmospheric atmosphere sintering furnace at a maximum sintering temperature of 1350°C for 2 hours to produce porous ceramic material.

[0068] 4) Performance Testing

[0069] The density, flexural strength, and apparent porosity of the porous ceramic material prepared in step 3) were tested, and the color of the porous ceramic material was recorded. The porosity was tested according to GB / T25995-2010, and the flexural strength was tested according to GBT_6569-2006.

[0070] Comparative Example 4

[0071] The only difference between this comparative example and Example 1 is that in this comparative example, 40 parts of the pore-forming agent polymethyl methacrylate microspheres are added in step 1), thus changing the ratio of the pore-forming agent. The rest of the process is the same as in Example 1. The specific steps are as follows:

[0072] 1) Preparation of slurry

[0073] By weight, 42 parts of particle size D 10 =0.3μm, D 50 =0.5μm, D 90 =3μm alumina micro powder, 11 parts with a particle size of D 10 =0.8μm, D 50 =1μm, D 90 =5μm silica micro powder, 3 parts iron oxide micro powder, 2 parts chromium trioxide, 1.5 parts cobalt trioxide, 0.5 parts nickel oxide and 24 parts deionized water were mixed. Then 1.5 parts polyacrylic acid, 7 parts N-hydroxymethylacrylic acid and 0.5 parts N,N'-methylenebisacrylamide were added. The mixture was ball-milled for 60 minutes until the powder was uniform. Then 38 parts coarse white corundum powder, 40 parts polymethyl methacrylate microspheres and 36 parts polyvinyl alcohol aqueous solution with a mass concentration of 5% were added. The mixture was poured into a rotary mixer and mixed at 2100 rpm for 2 minutes. The mixture was repeated three times to obtain a uniformly mixed porous ceramic slurry.

[0074] 2) Injection molding: Add 1 part of ammonium persulfate to the uniformly mixed porous ceramic slurry obtained in step 1), pour it into the mold, and place it in a water bath at a water temperature of 60°C for 30 minutes to wait for molding.

[0075] 3) Post-processing of materials

[0076] The shaped ceramic material prepared in step 2) was dried in a constant temperature and humidity chamber at 25°C and 80% relative humidity for 12 hours, at 40°C and 60% relative humidity for 12 hours, and at 80°C and 20% relative humidity for 24 hours. It was then degreased and sintered in an atmospheric atmosphere sintering furnace at a maximum sintering temperature of 1350°C for 2 hours to produce porous ceramic material.

[0077] 4) Performance Testing

[0078] The density, flexural strength, and apparent porosity of the porous ceramic material prepared in step 3) were tested, and the color of the porous ceramic material was recorded. The porosity was tested according to GB / T25995-2010, and the flexural strength was tested according to GBT_6569-2006.

[0079] Table 2. Effect of pore-forming agent ratio on the properties of porous ceramic materials

[0080]

[0081]

[0082] Table 2 shows that insufficient pore-forming agent leads to a decrease in the apparent porosity of the resulting porous ceramic material. This decrease in pore count increases the error rate during workpiece processing in the vacuum chuck. Conversely, excessive pore-forming agent, while increasing the apparent porosity, also reduces the material's density and flexural strength, significantly lowering its overall performance. Therefore, Example 1 strikes a balance between these two factors, providing both high apparent porosity and good mechanical properties, and mitigating the risk of breakage during product processing.

[0083] Comparative Example 5

[0084] The only difference between this comparative example and Example 1 is that, in this comparative example, coarse white corundum powder is not added in step 1). The rest of the process is the same as in Example 1. The specific steps are as follows:

[0085] 1) Preparation of slurry

[0086] By weight, 42 parts of particle size D 10 =0.3μm, D 50 =0.5μm, D 90=3μm alumina micro powder, 11 parts with a particle size of D 10 =0.8μm, D 50 =1μm, D 90 =5μm silica micro powder, 3 parts iron oxide micro powder, 2 parts chromium trioxide, 1.5 parts cobalt trioxide, 0.5 parts nickel oxide and 24 parts deionized water were mixed. Then 1.5 parts polyacrylic acid, 7 parts N-hydroxymethylacrylic acid and 0.5 parts N,N'-methylenebisacrylamide were added. The mixture was ball-milled for 60 minutes until the powder was uniform. Then 30 parts polymethyl methacrylate microspheres and 36 parts polyvinyl alcohol aqueous solution with a mass concentration of 5% were added. The mixture was poured into a rotary mixer and mixed at 2100 rpm for 2 minutes. The mixture was repeated three times to obtain a uniformly mixed porous ceramic slurry.

[0087] 2) Injection molding: Add 1 part of ammonium persulfate to the uniformly mixed porous ceramic slurry obtained in step 1), pour it into the mold, and place it in a water bath at a water temperature of 60°C for 30 minutes to wait for molding.

[0088] 3) Post-processing of materials

[0089] The shaped ceramic material prepared in step 2) was dried in a constant temperature and humidity chamber at 25°C and 80% relative humidity for 12 hours, at 40°C and 60% relative humidity for 12 hours, and at 80°C and 20% relative humidity for 24 hours. It was then degreased and sintered in an atmospheric sintering furnace at a maximum sintering temperature of 1350°C for 2 hours to obtain the ceramic material.

[0090] 4) Performance Testing

[0091] The density, flexural strength, and apparent porosity of the ceramic material prepared in step 3) were tested, and the color of the obtained porous ceramic material was recorded. Among them, the porosity was tested according to GB / T25995-2010; the flexural strength was tested according to GBT_6569-2006.

[0092] Table 3. Effects of coarse white corundum powder on porous ceramic materials

[0093]

[0094]

[0095] Table 3 shows that if no coarse white fused alumina powder is added to the slurry, the resulting ceramic material will essentially not form open pores. Electron microscopy reveals numerous circular closed pores. This is presumably because when all the white fused alumina particles are replaced with alumina powder, the fine alumina powder and silica liquid phase completely encapsulate the PMMA, forming non-interfering closed pores. In this patent, the white fused alumina used is an irregularly shaped, elongated block, while the alumina micropowder is spherical. Due to the shape and particle size of alumina, it has a higher packing density than white fused alumina. With the aid of sintering agents, the alumina micropowder forms a distinct sintering neck at 1450℃, grains begin to grow, and the pores between grain boundaries are gradually filled, leading to the disappearance of many pores. When white fused alumina is added, the large particles have a higher melting point than conventional alumina powder. At the current sintering temperature, their size and morphology are less likely to change, avoiding the formation of sintering necks and the significant grain growth process. Furthermore, its irregular morphology results in a lower packing density. When white fused alumina is added, the liquid phase formed by a small amount of alumina powder and a low proportion of silica only serves as a connector and cannot completely encapsulate the white fused alumina skeleton.

[0096] Example 2

[0097] 1) Preparation of slurry

[0098] By weight, 42 parts of particle size D 10 =0.3μm, D 50 =0.5μm, D 90 =3μm alumina micro powder, 11 parts with a particle size of D 10 =0.8μm, D 50 =1μm, D 90 =5μm silica micro powder, 3 parts iron oxide micro powder, 2 parts chromium trioxide, 1.5 parts cobalt trioxide, 0.5 parts nickel oxide and 60 parts deionized water were mixed. Then 1.5 parts polyacrylic acid, 7 parts N-hydroxymethylacrylic acid and 0.5 parts N,N'-methylenebisacrylamide were added. The mixture was ball-milled for 60 minutes until the powder was uniform. Then 38 parts coarse white corundum powder, 30 parts spherical graphite micro powder and 36 parts polyvinyl alcohol aqueous solution with a mass concentration of 5% were added. The mixture was poured into a rotary mixer and mixed at 2100 rpm for 2 minutes. The mixture was repeated three times to obtain a uniformly mixed porous ceramic slurry.

[0099] 2) Injection molding: Add 1 part of ammonium persulfate to the uniformly mixed porous ceramic slurry obtained in step 1), pour it into the mold, and place it in a water bath at a water temperature of 60°C for 30 minutes to wait for molding.

[0100] 3) Post-processing of materials

[0101] The shaped ceramic material prepared in step 2) was dried in a constant temperature and humidity chamber at 25°C and 80% relative humidity for 12 hours, at 40°C and 60% relative humidity for 12 hours, and at 80°C and 20% relative humidity for 24 hours. It was then degreased and sintered in an atmospheric atmosphere sintering furnace at a maximum sintering temperature of 1350°C for 2 hours to produce porous ceramic material.

[0102] 4) Performance Testing

[0103] The density, flexural strength, and apparent porosity of the porous ceramic material prepared in step 3) were tested, and the color of the porous ceramic material was recorded. The porosity was tested according to GB / T25995-2010, and the flexural strength was tested according to GBT_6569-2006.

[0104] Example 3

[0105] 1) Preparation of slurry

[0106] By weight, 42 parts of particle size D 10 =0.3μm, D 50 =0.5μm, D 90 =3μm alumina micro powder, 11 parts with a particle size of D 10 =0.8μm, D 50 =1μm, D 90 =5μm silica micro powder, 3 parts iron oxide micro powder, 2 parts chromium trioxide, 1.5 parts cobalt trioxide, 0.5 parts nickel oxide and 24 parts deionized water were mixed. Then 1.5 parts polyacrylic acid, 7 parts N-hydroxymethylacrylic acid and 0.5 parts N,N'-methylenebisacrylamide were added. The mixture was ball-milled for 60 minutes until the powder was uniform. Then 38 parts coarse white corundum powder, 30 parts industrial starch and 36 parts 5% polyethylene oxide aqueous solution were added. The mixture was poured into a rotary mixer and mixed at 2100 rpm for 2 minutes. The mixture was repeated three times to obtain a uniformly mixed porous ceramic slurry.

[0107] 2) Injection molding: Add 1 part of ammonium persulfate to the uniformly mixed porous ceramic slurry obtained in step 1), pour it into the mold, and place it in a water bath at a water temperature of 60°C for 35 minutes to wait for molding.

[0108] 3) Post-processing of materials

[0109] The shaped ceramic material prepared in step 2) was dried in a constant temperature and humidity chamber at 25°C and 80% relative humidity for 12 hours, at 40°C and 60% relative humidity for 12 hours, and at 80°C and 20% relative humidity for 24 hours. It was then degreased and sintered in an atmospheric atmosphere sintering furnace at a maximum sintering temperature of 1350°C for 2 hours to produce porous ceramic material.

[0110] 4) Performance Testing

[0111] The density, flexural strength, and apparent porosity of the porous ceramic material prepared in step 3) were tested, and the color of the porous ceramic material was recorded. The porosity was tested according to GB / T25995-2010, and the flexural strength was tested according to GBT_6569-2006.

[0112] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0113] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for producing a black alumina porous ceramic material for vacuum chuck, characterized by, The method comprises the following steps: 1) 4-5 parts of alumina micro-powder, 10-11 parts of silica micro-powder, 7-8 parts of colorant and 20-25 parts of water are mixed by weight, then 0.5-1 parts of polyacrylic acid, 6-8 parts of N-hydroxymethyl acrylamide, N, N'-methylene bisacrylamide are added, and ball milling is performed for 30-60 min, wherein the colorant is a mixture of iron oxide micro-powder, dichromium trioxide, cobalt trioxide and nickel monoxide in a weight ratio of (2.8-3.2):(1.8-2.2):(1.3-1.5):(0.4-0.6); 2) 35-40 parts of white corundum coarse powder, 30-35 parts of pore-forming agent and 35-38 parts of suspending agent are added, and centrifugal stirring is performed for 2-3 min, and the process is repeated for 3-5 times; 3) 1-1.5 parts of ammonium persulfate is added and stirred uniformly, then poured into a mold, and left to stand at 60-65 ℃ for 30-45 min; 4) demolding, drying and then debinding and sintering are performed to obtain the material.

2. The method for preparing a porous black alumina ceramic material for vacuum suction cups according to claim 1, characterized in that, In step 1), the particle size of the alumina fine powder is: D 10 = 0.3 to 0.35 μm; D 50 = 0.5 to 0.55 μm; D 90 = 3 to 3.1 μm.

3. The method for preparing a porous black alumina ceramic material for a vacuum suction cup according to claim 1 or 2, characterized in that, In step 1), the particle size of the silica fine powder is: D 10 = 0.8 to 0.85 μm; D 50 = 1 to 1.05 μm; D 90 = 5 to 5.2 μm.

4. The method for preparing a porous black alumina material for vacuum suction cups according to claim 1, characterized in that, In step 2), the white corundum coarse powder is an electrically fused white corundum, and the particle size is: D 10 = 10-11 μm; D 50 = 15-16 μm; D 90 = 25-26 μm.

5. A method for preparing a porous black alumina ceramic material for a vacuum chuck according to claim 1 or 4, characterized in that, In step 2), the pore-forming agent is one or several of polymethyl methacrylate, spherical graphite, industrial starch, with particle sizes of: D 10 = 30-40 μm; D 50 = 45-55 μm; D 90 = 55-70 μm.

6. The method for preparing a porous black alumina ceramic material for vacuum suction cups according to claim 1, characterized in that, In step 2), the suspending agent is one or more of polyvinyl alcohol and polyethylene oxide aqueous solution with a concentration of 5-6 wt%.

7. The method for preparing a porous black alumina ceramic material for vacuum suction cups according to claim 1, characterized in that, In step 4), the drying process is as follows: drying at 40-45 ℃ and a relative humidity of 80-85% for 24-30 h, then drying at 60-65 ℃ and a relative humidity of 40-45% for 24-30 h, and finally drying at 80-85 ℃ and a relative humidity of 20-25% for 24-30 h.

8. The method for preparing a porous black alumina ceramic material for vacuum suction cups according to claim 1, characterized in that, In step 4), the debinding and sintering temperature is 1400-1450 ℃, and the debinding and sintering time is 2-3 h.

9. A black alumina porous ceramic material for vacuum chuck prepared by the method according to any one of claims 1-8.

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