Ceramic joint bearing and preparation method

Abstract

The invention provides a ceramic knuckle bearing and a preparation method, and belongs to the technical field of knuckle bearing manufacturing. The knuckle bearing comprises an inner ring and an outer ring, and the maximum sectional area position of the inner ring is located in the spherical cambered surface of the outer ring; the inner ring comprises the following raw materials in parts by weight: 3-6 parts of a monomer, 7-12 parts of a cross-linking agent, 0.1-0.5 part of a dispersing agent, 0.3-0.5 part of an initiator, 0.02-0.04 part of a catalyst and 80-100 parts of aluminum oxide powder; the raw materials of the outer ring comprise 60-70 parts of aluminum oxide powder and white corundum powder, and the mass ratio of the white corundum powder to the aluminum oxide powder is 0.4-1. The inner ring and the outer ring are different in composition and adopt a gel casting method, so that the shrinkage amounts of the inner ring and the outer ring are different in the sintering process, and the inner ring and the outer ring can be naturally separated in the preparation process and cannot be sintered together.

Description

Technical Field

[0001] The invention belongs to the technical field of spherical bearing manufacturing and relates to a ceramic spherical bearing and a preparation method thereof. Background Art

[0002] Spherical plain bearings, also known as spherical sliding bearings, are mainly composed of an outer ring with an inner spherical surface and an inner ring with an outer spherical surface. Spherical plain bearings can swing at any angle and have the advantages of simple structure, small size, and large load-bearing capacity. They are widely used in agricultural machinery, aerospace, automobiles and other fields. Due to the shortcomings of metal materials such as poor corrosion resistance and large expansion coefficient, spherical plain bearings made of metal are difficult to work stably in harsh environments. Compared with metal materials, ceramic materials have excellent properties such as non-magnetic conductivity, corrosion resistance, light weight, and high precision. Therefore, ceramic spherical plain bearings have excellent performance that metal spherical plain bearings cannot match, especially the ability to adapt to harsh environments and have a longer service life.

[0003] At present, spherical plain bearings made of metal are often manufactured by extrusion molding, but this method involving plastic deformation is not suitable for spherical plain bearings made of ceramic materials. Most spherical plain bearings made of ceramic materials adopt the notch assembly method, that is, first manufacture an outer ring with a notch, install the inner ring from the notch position, and then fill the notch position of the outer ring. Since there are notches on the outer ring using this method, the stress state of the outer ring is uneven, which will affect the service life of the spherical plain bearing. The Chinese patent "A manufacturing method for integrally forming spherical plain bearings" with application number 2023104564233 provides a technical solution for preparing a blank by dry pressing, first sintering the inner ring, and then placing the formed inner ring into the outer ring blank for sintering. It is difficult to control the uniformity of the density of the internal blank of the spherical plain bearing prepared by dry pressing, and stratification is easy to occur inside the blank. In addition, it needs to go through multiple heating-cooling processes, which is easy to crack during the sintering process; and the manufacturing cycle of multiple sintering is long. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a ceramic spherical bearing and a preparation method. The gel injection molding method is adopted to prepare the inner ring and the outer ring using ceramic raw materials with different shrinkage amounts and sinter them at the same time. During the sintering process, the inner ring and the outer ring have different shrinkage amounts to prevent the inner and outer rings from sticking together. The materials inside the inner and outer ring blanks are evenly distributed, and they are not easy to crack during the sintering process. The yield is high, and the ceramic spherical bearing can be prepared by integral molding and sintering.

[0005] In order to achieve the above-mentioned object, the first aspect of the present invention provides a ceramic spherical bearing, comprising: an inner ring and an outer ring; the outer side of the spherical arc surface of the inner ring surrounds the spherical arc surface of the outer ring, and the surface of the inner ring is provided with an isolation layer; The inner ring is prepared from the following raw materials in parts by weight: 3-6 parts of monomer, 7-12 parts of cross-linking agent, 0.1-0.5 parts of dispersant, 0.3-0.5 parts of initiator, 0.02-0.04 parts of catalyst and 80-100 parts of alumina powder; The outer ring is prepared from the following raw materials in parts by weight: 3-6 parts of monomer, 7-12 parts of cross-linking agent, 0.1-0.5 parts of dispersant, 0.3-0.5 parts of initiator, 0.02-0.04 parts of catalyst, 60-70 parts of alumina powder and white corundum powder, and the mass ratio of white corundum powder to alumina powder is 0.4-1; The particle size of the aluminum oxide powder is 300-700 nm; the particle size of the white corundum powder is 0.8-1.5 μm.

[0006] The second aspect of the present invention provides a method for preparing the above-mentioned ceramic spherical plain bearing, comprising the following steps: S1. Mixing the raw materials for preparing the inner ring to obtain an inner ring slurry, injecting the inner ring slurry into a spherical bearing inner ring mold, solidifying to obtain an inner ring blank, and providing a boron nitride isolation layer on the surface of the inner ring blank; S2. Mix the raw materials for preparing the outer ring to obtain outer ring slurry, put the inner ring blank into the outer ring mold of the spherical plain bearing, inject the outer ring slurry between the inner ring blank and the outer ring mold, and solidify to obtain the spherical plain bearing blank; S3, after drying the spherical plain bearing blank, debinding at 630-650°C, and then sintering at 1400-1600°C to obtain a ceramic spherical plain bearing product.

[0007] The beneficial effects of the present invention are: 1. The ceramic spherical bearing provided by the present invention comprises an inner ring made of ceramic material and an outer ring made of ceramic material. Since the inner ring and the outer ring have different compositions, their respective shrinkage amounts during the sintering process are different, so that the inner ring and the outer ring can be naturally separated during the preparation process without being sintered together.

[0008] 2. The present invention adopts a gel injection molding method to prepare ceramic spherical bearings. The biggest advantage of gel injection molding is that the blank shrinks evenly during sintering, avoiding deformation of the spherical bearing during the sintering process, thereby obtaining an integral all-ceramic spherical bearing. In particular, during the debinding process, the organic polymers generated by monomers, cross-linking agents and other components inside the ceramic green body are decomposed into small molecules and discharged in the form of gas, thereby obtaining a blank with only ceramic powder accumulation. During the sintering process, since the shrinkage amplitudes of the outer ring blank mixed with white corundum powder and the inner ring blank without white corundum are inconsistent, and the shrinkage amplitude of the inner ring is larger, it can effectively prevent the inner and outer rings of the spherical bearing from sintering together during sintering, thereby obtaining an integral all-ceramic spherical bearing, avoiding the assembly between the inner and outer rings of the spherical bearing, and being able to prepare a ceramic spherical bearing without a notch. In addition, one-time debinding and sintering is a continuous heating and heat preservation process, and one-time sintering molding avoids the risk of material cracking caused by repeated heating, has low preparation difficulty, and a stable molding method, thereby improving the production efficiency of the spherical bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0010] Figure 1 Schematic diagram of the ceramic spherical bearing in Example 1.

[0011] Figure 2 Schematic diagram of the inner ring mold in Example 1.

[0012] Figure 3 Schematic diagram of the outer ring mold in Example 1.

[0013] Figure 4 This is a physical picture of the inner ring blank in Example 1.

[0014] Figure 5 This is a physical picture of the spherical bearing blank in Example 1.

[0015] Among them, 1. inner ring; 11. hollow channel; 12. spherical arc surface of inner ring; 2. outer ring; 21. opening; 22. spherical arc surface of outer ring; 31. inner ring outer mold; 32. mold core; 33. first spherical inner surface; 41. outer ring forming surface; 42. second spherical inner surface; 5. inner ring blank; 6. outer ring blank. DETAILED DESCRIPTION

[0016] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0017] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0018] A ceramic spherical bearing, comprising: an inner ring and an outer ring; the inner ring's spherical arc surface surrounds the outer ring's spherical arc surface on its outer side and is separated from the outer ring's spherical arc surface by a set gap; the inner ring's maximum cross-sectional area is located inside the outer ring's spherical arc surface, and the outer ring's opening area is smaller than the inner ring's maximum cross-sectional area; the inner ring surface is provided with an isolation layer; The inner ring is prepared from the following raw materials in parts by weight: 3-6 parts of monomer, 7-12 parts of cross-linking agent, 0.1-0.5 parts of dispersant, 0.3-0.5 parts of initiator, 0.02-0.04 parts of catalyst and 80-100 parts of alumina powder; The outer ring is prepared from the following raw materials in parts by weight: 3-6 parts of monomer, 7-12 parts of cross-linking agent, 0.1-0.5 parts of dispersant, 0.3-0.5 parts of initiator, 0.02-0.04 parts of catalyst, 60-70 parts of alumina powder and white corundum powder, and the mass ratio of white corundum powder to alumina powder is 0.4-1; The particle size of the aluminum oxide powder is 300-700 nm; the particle size of the white corundum powder is 0.8-1.5 μm.

[0019] Since raw materials containing white corundum and raw materials not containing white corundum shrink to different degrees at high temperatures, different raw materials are selected for the inner ring and the outer ring, respectively, so that the inner ring and the outer ring can be separated at high temperature to obtain a set gap, thereby obtaining a ceramic spherical plain bearing without assembly gaps; since the shrinkage rates of green bodies made of different particle sizes are different during sintering, and the different surface areas of powders of different particle sizes will lead to phase differences formed during the sintering and melting process, it is necessary to comprehensively consider the deformation degree of the green body during sintering and the desired phase ratio to design the particle size and mass ratio of the powder.

[0020] Optionally, the isolation layer includes one or both of boron nitride or carbon nitride powder, which are stable at high temperatures and can prevent the grains of the inner ring raw material and the outer ring raw material from fusing and bonding together at the interface during the sintering process.

[0021] Optionally, the monomer is one of hydroxymethyl acrylamide, methacrylamide and acrylamide, which is used as a raw material for gel casting molding, and a green body with a set strength range is obtained under the action of a cross-linking agent.

[0022] Optionally, the cross-linking agent is one of N,N-methylenebisacrylamide and methylenebisacrylamide, which functions to cross-link the above monomers to form a three-dimensional network structure, thereby improving the strength and stability of the gel, thereby preparing a green body with a set shape.

[0023] Optionally, the dispersant includes one or more of 2-phosphonobutane-1,2,4-tricarboxylic acid, ammonium polyacrylate and ammonium citrate, and the dispersant is used to evenly disperse the alumina powder and the white corundum powder in the gel raw material, so as to obtain inner ring blank and outer ring blank with uniform composition, so that the shrinkage degree of each position of the blank during high-temperature sintering is uniform, avoiding stratification or large deformation inside the blank.

[0024] Optionally, the initiator is ammonium persulfate, which functions to promote the cross-linking reaction between the cross-linking agent and the monomer.

[0025] Optionally, the catalyst is tetramethylethylenediamine, which functions to promote the progress of the cross-linking reaction under set reaction conditions.

[0026] Optionally, the raw materials for preparing the inner ring and the outer ring further include a pH adjuster, and the pH adjuster includes ammonia water and hydrochloric acid, and suitable reaction conditions are created by adjusting the pH.

[0027] Optionally, the raw materials for preparing the inner ring and the outer ring also include a defoaming agent, which is n-octanol or isooctyl alcohol. The defoaming agent can eliminate bubbles in the gel raw material and avoid residual pores in the green body, thereby improving the density and uniformity of the green body and further avoiding the formation of defects such as pores during high-temperature sintering.

[0028] Optionally, the isolation layer includes one or more of boron nitride or carbon nitride powder.

[0029] Optionally, the shrinkage ratio of the inner ring material during sintering at 1400~1600℃ is 15%~18%; the shrinkage ratio of the outer ring material during sintering at 1400~1600℃ is 14%~17%, and the shrinkage ratio of the inner ring material is greater than that of the outer ring material, so that a gap is generated between the inner and outer ring blanks, thereby obtaining a ceramic spherical bearing that can rotate freely.

[0030] White corundum is an artificial inorganic material whose main component is aluminum oxide. The content of aluminum oxide (Al2O3) is more than 98%. It is added with iron oxide, silicon oxide and other ingredients. It is white in appearance and is usually made by melting at a high temperature of more than 2000 degrees in an electric arc and then cooling.

[0031] The white corundum powder used in the following embodiments is selected from the products of Shanghai Chaowei Nanotechnology Co., Ltd., with a particle size of 1 μm; the alumina powder is also selected from the products of Shanghai Chaowei Nanotechnology Co., Ltd., with a particle size of 500 nm; since the white corundum product itself has undergone high-temperature calcination during the preparation process, the degree of grain growth during the re-sintering process is relatively small, and the shrinkage rate of the material can be adjusted by the proportion of white corundum.

[0032] The method for preparing the ceramic spherical bearing comprises the following steps: S1. Mixing the raw materials for preparing the inner ring to obtain inner ring slurry, injecting the inner ring slurry into a spherical bearing inner ring mold, solidifying to obtain an inner ring blank, and setting an isolation layer on the surface of the inner ring blank; S2. Mix the raw materials for preparing the outer ring to obtain outer ring slurry, put the inner ring blank into the outer ring mold of the spherical plain bearing, inject the outer ring slurry between the inner ring blank and the outer ring mold, and solidify to obtain the spherical plain bearing blank; S3, after drying the spherical plain bearing blank, debinding at 630-650°C, and then sintering at 1400-1600°C to obtain a ceramic spherical plain bearing product.

[0033] By the above method, a spherical bearing blank is prepared in steps S1 and S2, at which time there is no gap between the inner ring blank and the outer ring blank, and the two support each other to maintain their shape. In step S3, the spherical bearing blank is sintered into a spherical bearing product made of ceramic material, and a set gap is generated between the inner ring and the outer ring, thereby obtaining a ceramic spherical bearing product without assembly gap.

[0034] Optionally, in S1, the monomer, the cross-linking agent and the set amount of water are mixed and stirred to obtain a first solution; a dispersant is added to the first solution, and the pH is adjusted to 9±0.5 with a pH adjuster, and then a defoaming agent and alumina powder are added to obtain a first slurry, the first slurry is ball-milled to defoam, and then a catalyst and an initiator are added to perform a second defoaming to obtain an inner ring slurry, in which the alumina powder is fully dispersed, and an inner ring blank with a certain strength can be obtained by injection molding.

[0035] Optionally, in S1, the ball milling method is: placing the first slurry into a nylon ball mill at a ball-to-material ratio of (1-1.5):3, and ball milling at a speed of 250-290 r / min for 4-6 hours to fully disperse the alumina powder. Since the ball milling time is short, the particle size of the alumina powder will not be significantly changed.

[0036] Optionally, in S1, the degassing method for the first slurry is vacuum degassing for 15 to 20 minutes, and the second degassing method is vacuum degassing for 2 to 3 minutes; the two degassing processes are respectively performed after the raw materials are added and mixed twice to fully eliminate the bubbles.

[0037] Optionally, in S1, the solidification method is to place at 60-70°C for 20-30 minutes, so as to obtain an inner ring blank with a certain strength. The inner ring blank can remain unchanged during the injection and solidification of the outer ring slurry in S2, and serve as a mold core to assist in the molding of the outer ring blank.

[0038] Optionally, in S2, the monomer, the cross-linking agent and the set amount of water are mixed and stirred to obtain a first solution; a dispersant is added to the first solution, and the pH is adjusted to 9±0.5 with a pH adjuster, and then a defoaming agent, alumina powder and white corundum powder are added to obtain a second slurry, the second slurry is ball-milled and defoamed, and then a catalyst and an initiator are added to perform a second defoaming to obtain an outer ring slurry. The preparation methods of the outer ring slurry and the inner ring slurry are basically the same, so that the inner ring blank and the outer ring blank have basically the same solidification requirements, debinding requirements and sintering temperature requirements, so that the inner ring blank and the outer ring blank complete the solidification, debinding and sintering processes within the same temperature range.

[0039] Optionally, in S2, the ball milling method of the second slurry is: placing the second slurry in a nylon ball mill at a ball-to-material ratio of (1-1.5):3, and ball milling at a speed of 250-290 r / min for 4-6 hours to fully disperse the alumina powder and the white corundum powder. Since the ball milling time is short, the particle size of the alumina powder and the white corundum powder will not be significantly changed.

[0040] Optionally, in S2, the degassing method is vacuum degassing for 15 to 20 minutes, and the second degassing method is vacuum degassing for 2 to 3 minutes. The two degassing processes are respectively performed after the raw materials are added and mixed twice to fully eliminate the bubbles.

[0041] Optionally, in S2, the solidification method is to place the blank at 60-70°C for 20-30 minutes, so as to obtain a spherical plain bearing blank with a certain strength after demolding.

[0042] Optionally, in S3, the drying method is to dry the spherical bearing blank at 30-40°C for 5-7 hours, and then dry it at 45-50°C for 44-52 hours to remove water from the blank and prevent the blank from bursting due to excessive expansion of water during subsequent heating.

[0043] Optionally, in S3, the debinding method is: heating to 130-140°C at a rate of 1-1.5°C / min, and then heating to 630-650°C at a rate of 1.5-2°C / min and keeping warm for 30-40 min. During this process, organic polymers generated by monomers, cross-linking agents and other components are decomposed into small molecules and discharged in the form of gas, thereby obtaining a green body with only ceramic powder deposited.

[0044] Optionally, in S3, the sintering method is: heating to 1500~1550℃ at a rate of 1.5~2℃ / min at the debinding temperature and keeping warm for 180~200 min, then cooling to room temperature with the furnace, and the ceramic powder remaining after debinding is formed in situ to maintain the shape characteristics of the blank; due to the different shrinkage degrees of the inner ring blank and the outer ring blank, a gap is gradually generated between the inner ring blank and the outer ring blank during the sintering process, and a spherical bearing that can rotate freely is obtained; and the debinding and sintering are a continuous heating and insulation process, and the one-time sintering and forming can avoid the risk of material cracking caused by repeated heating, the preparation difficulty is low, the forming method is stable, and the production efficiency of the spherical bearing is improved.

[0045] Example 1 A ceramic spherical bearing, such as Figure 1 As shown, it includes an inner ring 1 and an outer ring 2, and both the inner ring 1 and the outer ring 2 are rotating bodies. Figure 1 As shown, the inner ring 1 includes an inner ring spherical arc surface 12, and the hollow channel 11 is located at the central axis position of the inner ring spherical arc surface 12; the outer ring 2 is surrounded by the outer side of the inner ring 1, and the outer ring spherical arc surface 22 is provided inside the outer ring 2, and the outer ring spherical arc surface 22 is separated from the inner ring spherical arc surface 12 by a set gap, so that the inner ring 1 can stably rotate freely in the outer ring 2, and the upper and lower ends of the outer ring 2 have openings 21, and the maximum cross-sectional area of ​​the inner ring 1 is located inside the outer ring 2, and the area of ​​the opening 21 of the outer ring 2 is smaller than the maximum cross-sectional area of ​​the inner ring 1. The hollow channel 11 is located in the opening 21 for assembling rods or other accessories, and the area of ​​the opening 21 of the outer ring 2 is smaller than the maximum cross-sectional area of ​​the inner ring spherical arc surface 12. The outer diameter of the outer ring 2 is 21.25mm, and the gap between the inner ring 1 and the outer ring 2 is about 0.5mm. Since the inner ring 1 and the outer ring 2 are both made of ceramics, they are brittle and have poor deformation ability, so the inner and outer rings cannot be prepared by assembly methods. Figure 1 Products shown.

[0046] The raw materials for preparing the inner ring include the following raw materials: 4.6 g of hydroxymethyl acrylamide (monomer), 0.46 g of N,N-methylenebisacrylamide (cross-linking agent), 0.46 g of 2-phosphonobutane-1,2,4-tricarboxylic acid (dispersant), 0.5 g of ammonium persulfate solution (initiator) with a mass concentration of 10%, 0.2 g of tetramethylethylenediamine (catalyst) and 92 g of alumina powder with a particle size of 500 nm; The outer ring is prepared from the following raw materials in parts by mass: 4.6 g of hydroxymethyl acrylamide (monomer), 0.46 g of N,N-methylenebisacrylamide (cross-linking agent), 0.46 g of 2-phosphonobutane-1,2,4-tricarboxylic acid (dispersant), 0.5 g of 10% ammonium persulfate solution (initiator), 0.2 g of tetramethylethylenediamine (catalyst), 64.4 g of alumina powder with a particle size of 500 nm, and 27.6 g of white corundum powder with a particle size of 1 μm.

[0047] The preparation mold of the ceramic spherical plain bearing used in this embodiment includes an inner ring mold and an outer ring mold; like Figure 2 As shown, the inner ring mold includes an inner ring outer mold 31 and a mold core 32. The inner surface of the inner ring outer mold 31 includes a first spherical inner surface 33. The cavity between the inner ring outer mold 31 and the mold core 32 is used for gel injection molding of the inner ring blank. The axis 32 of the mold core coincides with the axis of the first spherical inner surface 33. To facilitate demolding, the inner ring outer mold 31 adopts an upper and lower clamping method.

[0048] like Figure 3 As shown, the outer ring mold includes an outer ring molding surface 41, and a second spherical inner surface 42 is arranged at the end of the outer ring molding surface 41. The second spherical inner surface 42 has the same curvature as the first spherical inner surface 33 and is used to support the inner ring blank 5, so that a cavity with a closed bottom end is formed between the inner ring blank 5 and the outer ring mold, and the cavity is used for gel injection molding of the outer ring blank 6; to facilitate demolding, the outer ring mold adopts a left-right mold closing method.

[0049] The preparation method of this embodiment includes: S1. Weigh 20 ml of water, add 4.6 g of hydroxymethyl acrylamide and 0.46 g of N,N-methylene acrylamide to the water to prepare a premixed solution, and stir the premixed solution on a magnetic stirrer for 10 min, until the particles are completely dissolved to obtain a premixed liquid; 0.46 g of dispersant is added to the premixed liquid, and ammonia water and hydrochloric acid are used to adjust the pH to 9, then a set amount of n-octanol (defoaming agent) is added, and then 92 g of alumina powder is added and stirred evenly to obtain a first slurry; the first slurry is placed in a nylon ball mill at a ball-to-material ratio of 1:3, ball-milled at a speed of 270 r / min for 5 hours, and then stirred and defoamed in a vacuum defoaming device for 15 minutes, and then 0.2 g of tetramethylethylenediamine (catalyst) and 0.5 g of ammonium persulfate aqueous solution (initiator) are added to the defoamed first slurry in sequence, and then the slurry is placed in a vacuum defoaming device and stirred and defoamed for 2 minutes to obtain an inner ring slurry; the obtained inner ring slurry is poured into the inner ring mold, and after being placed at 60°C for 20 minutes, the slurry is self-cured, and then demolded to obtain the following Figure 4The inner ring blank 5 shown has a spherical diameter of 24.5 mm, and a boron nitride isolation layer with a thickness of 0.2 mm is sprayed on the outer surface of the inner ring blank.

[0050] S2, repeat the slurry preparation process in step S1, but replace 92g of alumina powder with 27.6g of white corundum powder and 64.4g of alumina powder to obtain a second slurry, such as Figure 3 As shown, the inner ring blank 5 is placed in the outer ring mold, and the outer ring slurry is injected between the inner ring blank 5 and the outer ring mold. After being placed at 60°C for 20 minutes, the slurry is self-cured, and then demolded to obtain the outer ring blank 6; the preparation is as shown in Figure 5 The spherical plain bearing blank shown includes an outer ring blank 6 and an inner ring blank 5 , and a boron nitride isolation layer is provided between the inner ring blank 5 and the outer ring blank 6 .

[0051] S3. Dry the spherical bearing blank at 40°C for 6 hours, then place it in a 45°C oven and dry it for 48 hours to obtain a ceramic green body. Place the ceramic green body flat in a furnace, heat it from room temperature to 132°C at a rate of 1.5°C / min, and then heat it to 650°C at a rate of 2°C / min and keep it warm for 30 minutes to remove the binder; then continue to heat it to 1500°C at a rate of 2°C / min and keep it warm for 180 minutes, cool it to room temperature with the furnace, and obtain a ceramic spherical bearing product with an outer diameter of 21.25mm, a gap between the inner ring and the outer ring of about 0.5mm, the inner ring can rotate freely in the outer ring, and the rotating axis remains stable.

[0052] In the above preparation method, the role of ball milling includes increasing the fluidity of the slurry, and due to the short ball milling time, it has almost no effect on the particle size; the debinding process includes a heating and heat preservation process below 650°C, during which the organic polymers inside the ceramic green body are decomposed into small molecules and discharged in the form of gas, thereby obtaining a green body with only ceramic powder accumulation. Due to the low temperature in the debinding stage, the size will not change significantly. During the sintering process, since the shrinkage range of the outer ring green body mixed with white corundum powder and the inner ring green body without white corundum is inconsistent, and the shrinkage range of the inner ring is larger, the gap between the inner ring and the outer ring can be obtained in this process, and then the overall full ceramic spherical bearing is obtained, avoiding the assembly between the inner and outer rings of the spherical bearing; although the thickness of the inner and outer rings at different positions is different, and the shrinkage degree of the positions with different thicknesses is different, since the inner and outer rings are both rotating bodies, and the shape of the inner and outer rings is designed, the difference in shrinkage degree does not affect the relative rotation between the inner and outer rings.

[0053] Example 2 The dimensions of the ceramic spherical bearing in this embodiment are the same as those in Embodiment 1, except that: The raw materials for preparing the inner ring include the following raw materials: 4.6 g of hydroxymethyl acrylamide (monomer), 0.46 g of N,N-methylenebisacrylamide (cross-linking agent), 0.46 g of 2-phosphonobutane-1,2,4-tricarboxylic acid (dispersant), 0.5 g of 10% ammonium persulfate solution (initiator), 0.2 g of tetramethylethylenediamine (catalyst) and 92 g of alumina powder with a particle size of 500 nm; The raw materials for preparing the outer ring include: 4.6g of hydroxymethyl acrylamide (monomer), 0.46g of N,N-methylenebisacrylamide (cross-linking agent), 0.46g of 2-phosphonobutane-1,2,4-tricarboxylic acid (dispersant), 0.5g of ammonium persulfate solution (initiator) with a concentration of (10%), 0.2g of tetramethylethylenediamine (catalyst), 64.4g of alumina powder with a particle size of 500nm and 27.6g of white corundum powder with a particle size of 1μm.

[0054] The preparation method is the same as that in Example 1, except that: The temperature in step S3 is appropriately adjusted, including: the drying temperature of the green body is changed to 50°C for 24 hours, then dried at 60°C to constant weight, and the sintering temperature is increased to 1600°C.

[0055] Comparative Example 1 A ceramic spherical bearing, the raw materials, gel injection molding mold and preparation method used are the same as those in Example 1, except that: in the preparation raw materials of the outer ring, the total amount of white corundum and alumina is consistent with that in Example 1, but the ratio is 1:4, that is, 73.6g of alumina powder and 18.4g of white corundum powder. After preparation, the inner ring of the spherical bearing shrinks greatly relative to the outer ring, the gap formed is large, the movable range of the inner ring is large, and it is difficult to maintain stability during rotation.

[0056] Comparative Example 2 A ceramic spherical bearing, the raw materials, gel injection molding mold and preparation method used are the same as those in Example 1, except that: in the preparation raw materials of the outer ring, the total amount of white corundum and alumina is consistent with that in Example 1, but the ratio is 4:1, that is, 18.4g of alumina powder and 73.6g of white corundum powder. After the preparation is completed, the shrinkage of the inner ring of the spherical bearing relative to the outer ring is too small. Even if a boron nitride isolation layer is sprayed, the shrinkage between the inner ring and the outer ring of the spherical bearing causes surface wrinkling, resulting in sintering and adhesion, and the inner ring cannot rotate.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A ceramic spherical bearing, characterized in that: include: Inner ring and outer ring; the outer side of the spherical arc surface of the inner ring surrounds the spherical arc surface of the outer ring, and the surface of the inner ring is provided with an isolation layer; The inner ring is prepared from the following raw materials in parts by weight: 3-6 parts of monomer, 7-12 parts of cross-linking agent, 0.1-0.5 parts of dispersant, 0.3-0.5 parts of initiator, 0.02-0.04 parts of catalyst and 80-100 parts of alumina powder; The outer ring is prepared from the following raw materials in parts by weight: 3-6 parts of monomer, 7-12 parts of cross-linking agent, 0.1-0.5 parts of dispersant, 0.3-0.5 parts of initiator, 0.02-0.04 parts of catalyst, 60-70 parts of alumina powder and white corundum powder, and the mass ratio of white corundum powder to alumina powder is 0.4-1; The particle size of the alumina powder is 300-700 nm; the particle size of the white corundum powder is 0.8-1.5 μm.

2. The ceramic spherical plain bearing according to claim 1, characterized in that: The monomer is one of hydroxymethyl acrylamide, methacrylamide and acrylamide; The cross-linking agent includes one of N,N-methylenebisacrylamide and methylenebisacrylamide; The dispersant includes one or more of 2-phosphonobutane-1,2,4-tricarboxylic acid, polyacrylic acid amine and ammonium citrate; The raw materials for preparing the inner ring and the outer ring also include a defoamer, and the defoamer is n-octanol or isooctyl alcohol; The initiator is ammonium persulfate; The catalyst is tetramethylethylenediamine; The raw materials for preparing the inner ring and the outer ring further include a pH adjuster, and the pH adjuster includes ammonia water and hydrochloric acid.

3. The ceramic spherical plain bearing according to claim 1, characterized in that: The isolation layer includes one or both of boron nitride and carbon nitride powders.

4. The ceramic spherical plain bearing according to claim 1, characterized in that: The shrinkage ratio of the inner ring material during sintering at 1400-1600°C is 15%-18%; the shrinkage ratio of the outer ring material during sintering at 1400-1600°C is 14%-17%; and the shrinkage ratio of the inner ring material is greater than that of the outer ring material.

5. A method for preparing a ceramic spherical bearing according to claim 1, characterized in that: The following steps are involved: S1. Mixing the raw materials for preparing the inner ring to obtain an inner ring slurry, injecting the inner ring slurry into a spherical bearing inner ring mold, solidifying to obtain an inner ring blank, and providing a boron nitride isolation layer on the surface of the inner ring blank; S2. Mix the raw materials for preparing the outer ring to obtain outer ring slurry, put the inner ring blank into the outer ring mold of the spherical plain bearing, inject the outer ring slurry between the inner ring blank and the outer ring mold, and solidify to obtain the spherical plain bearing blank; S3, after drying the spherical plain bearing blank, debinding at 630-650°C, and then sintering at 1400-1600°C to obtain a ceramic spherical plain bearing product.

6. The method for preparing a ceramic spherical plain bearing according to claim 5, characterized in that: In S1, the monomer, the cross-linking agent and the set amount of water are mixed and stirred to obtain a first solution; a dispersant is added to the first solution, and the pH is adjusted to 9±0.5 with a pH adjuster, and then a defoaming agent and alumina powder are added to obtain a first slurry, and the first slurry is ball-milled to defoam, and then a catalyst and an initiator are added to perform a second defoaming to obtain an inner circle slurry.

7. The method for preparing a ceramic spherical plain bearing according to claim 6, characterized in that: In S1, the ball milling method is: putting the first slurry into a nylon ball milling tank at a ball-to-material ratio of (1-1.5):3, and ball milling at a speed of 250-290 r / min for 4-6 hours; In S1, the degassing method of the first slurry is vacuum degassing for 15 to 20 minutes, and the second degassing method is vacuum degassing for 2 to 3 minutes; In S1, the solidification method is to place at 60-70° C. for 20-30 minutes.

8. The method for preparing a ceramic spherical plain bearing according to claim 5, characterized in that: In S2, a monomer, a cross-linking agent and a set amount of water are mixed and stirred to obtain a first solution; a dispersant is added to the first solution, and the pH is adjusted to 9±0.5 with a pH adjuster, and then a defoamer, alumina powder and white corundum powder are added to obtain a second slurry, and the second slurry is ball-milled to remove bubbles, and then a catalyst and an initiator are added to perform a second defoaming to obtain an outer ring slurry; In S2, the ball milling method is: the second slurry is placed in a nylon ball milling jar at a ball-to-material ratio of (1~1.5):3, and ball-milled at a speed of 250~290r / min for 4~6h; In S1, the degassing method of the second slurry is vacuum degassing for 15 to 20 minutes, and the second degassing method is vacuum degassing for 2 to 3 minutes; In S2, the solidification method is to place at 60-70° C. for 20-30 minutes.

9. The method for preparing a ceramic spherical plain bearing according to claim 5, characterized in that: In S3, the drying method is to dry the spherical plain bearing blank at 30-40° C. for 5-7 hours, and then dry it at 45-50° C. for 44-52 hours.

10. The method for preparing a ceramic spherical plain bearing according to claim 5, characterized in that: In S3, the debinding method is: heating to 130-140°C at a rate of 1-1.5°C / min, then heating to 630-650°C at a rate of 1.5-2°C / min and keeping the temperature for 30-40 minutes; The sintering method is: heating to 1500-1550°C at a rate of 1.5-2°C / min at the debinding temperature, keeping the temperature for 180-200 min, and then cooling to room temperature with the furnace.

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