A stress-assisted polishing method for polycrystalline ceramics

Abstract

The application discloses a stress catalytic polishing method of polycrystalline ceramics, and steps are as follows: collecting surface profile data of a polycrystalline ceramic workpiece, and fitting and calculating a surface fractal dimension of the polycrystalline ceramic workpiece by using a power spectrum density method; according to the fractal dimension, a polishing disc surface similar to the surface fractal dimension of the workpiece is prepared, and then the polishing disc is subjected to texturing treatment, wherein a workpiece with a high fractal dimension corresponds to small-interval texturing, and a workpiece with a low fractal dimension corresponds to large-interval texturing; finally, the polycrystalline ceramic workpiece and the texturing polishing disc are relatively moved in a polishing liquid medium, and polishing processing is completed. The application effectively increases the effective contact area of the workpiece and the polishing disc by fractal design and laser texturing preparation, improves the stress catalytic chemical reaction efficiency, realizes efficient and uniform removal of a reaction layer, solves the problem of chemical reaction difficulty in the polycrystalline ceramic polishing process, and relieves the "orange peel effect" of the surface, and is suitable for precision polishing of polycrystalline ceramics such as magnesium-aluminum spinel and aluminum nitride.

Description

Technical Field

[0001] This invention relates to the field of ultra-precision polishing technology, specifically to a stress-catalyzed polishing method for polycrystalline ceramics. Background Technology

[0002] Polycrystalline ceramics are inorganic non-metallic solid materials formed by numerous tiny grains bonded together at grain boundaries. The atoms within these ceramics are primarily linked by covalent or ionic bonds. These chemical bonds possess strong directionality and high bond saturation, giving polycrystalline ceramics their core characteristics of high hardness and excellent chemical stability. Furthermore, surface quality and processing precision are key factors determining their performance in service.

[0003] The strong directionality of covalent bonds and the strong hindrance of ionic bonds to crystal slip enable polycrystalline ceramics to operate stably under various complex conditions. However, this also makes them typical brittle and difficult-to-machine materials—these materials are difficult to plastically deform through dislocation mechanisms during processing. Therefore, in traditional polishing processes centered on abrasive mechanical action, the material removal method for polycrystalline ceramics is mainly brittle removal, and their surfaces are prone to defects such as pits and cracks, which seriously restricts the improvement of processing quality.

[0004] Generating an easily removable amorphous reaction layer on the workpiece surface through chemical reactions is a common technique for achieving high-quality polishing of hard and brittle polycrystalline ceramics. However, most polycrystalline ceramics are chemically stable and difficult to react effectively under normal temperature and pressure conditions. Therefore, improving the chemical reactivity during polycrystalline ceramic processing and promoting the formation of an easily removable reaction layer on its surface is the core key to achieving high surface quality and high-efficiency processing.

[0005] Chemical reactions require overcoming the inherent energy barrier of the material itself. For most ceramic materials, on the one hand, the extremely strong interatomic chemical bonds result in a high energy barrier, maintaining their stability under normal conditions; on the other hand, most ceramic materials have wide band gaps, requiring high energy for electrons to transition between bands, leading to a lack of freely moving electrons under normal conditions, further increasing the difficulty of chemical reactions. Therefore, reducing the energy barrier of polycrystalline ceramics during polishing and enhancing electron migration efficiency between the workpiece, polishing medium, and polishing pad are crucial challenges that need to be overcome to achieve high-quality, high-efficiency polishing of polycrystalline ceramics.

[0006] Currently, polishing methods for polycrystalline ceramics are mainly divided into three categories: non-contact polishing, flexible media polishing, and contact polishing. Among them, non-contact polishing mainly uses high-energy field polishing, which can achieve high-quality polishing of polycrystalline ceramics, but has the disadvantages of low processing efficiency and high cost; flexible media polishing is difficult to guarantee the shape accuracy of the workpiece, and there is still considerable room for improvement in processing efficiency for hard and brittle polycrystalline ceramics; contact polishing is still the main method for polishing polycrystalline ceramics, with chemical mechanical polishing being the primary method.

[0007] For example, Japanese patent application JP2003117806A discloses a method for mirror polishing of polycrystalline ceramics. This method uses a polishing slurry containing at least one of SiO2, MgO, and CeO2 as abrasives, and with a pH value adjusted to above 2 and below 9, to polish the polycrystalline ceramics through a mechanochemical polishing process. While this method can effectively polish polycrystalline ceramics, its processing mainly relies on the chemical activity of the abrasives and the polishing slurry. However, the differences in physicochemical properties between different grains of polycrystalline ceramic materials can lead to an "orange peel effect" on the workpiece surface.

[0008] Therefore, developing a high-quality, high-efficiency polishing method that can enhance the chemical reactivity of polycrystalline ceramics during the polishing process is of great theoretical significance and practical engineering application value. Summary of the Invention

[0009] The purpose of this invention is to address the deficiencies and shortcomings of the prior art by providing a stress-catalytic polishing method for polycrystalline ceramics.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] This invention provides a stress-catalytic polishing method for polycrystalline ceramics, comprising the following steps:

[0012] 1) Obtain the fractal dimension of the polycrystalline ceramic workpiece surface: Collect the surface contour data of the polycrystalline ceramic workpiece, and use the power spectral density method to fit and calculate the surface contour data to finally obtain the fractal dimension of the polycrystalline ceramic workpiece surface, which provides a basis for the subsequent preparation of polishing pads.

[0013] 2) Preparation of a polishing pad surface with a similar fractal dimension: Based on the fractal dimension of the polycrystalline ceramic workpiece surface calculated in step 1), a polishing pad surface with a similar fractal dimension to the polycrystalline ceramic workpiece surface is prepared. The surface of the polycrystalline ceramic workpiece to be polished is rough and has a large number of micro-peaks. The polishing pad surface is prepared based on the fractal dimension of the workpiece to be polished, so its surface will also form corresponding micro-peaks. During the polishing process, these micro-peaks on the polishing pad surface come into contact with the micro-peaks on the polycrystalline ceramic workpiece surface, generating contact stress, which in turn induces stress-catalyzed chemical reactions at the polishing interface. Specifically, at the contact points between the micro-peaks of the polishing pad and the micro-peaks of the polycrystalline ceramic workpiece, local high contact stress is generated. This high contact stress can cause the atoms on the polycrystalline ceramic workpiece surface to detach from their original lattice positions and change the local electronic structure, thereby reducing the activation energy of the reaction and promoting efficient chemical reactions on the workpiece surface. At the same time, the fractal-characteristic micro-peak design can statistically increase the effective contact points at the polishing interface, increase the critical activation volume of the interface, and thus significantly enhance the efficiency of stress-catalyzed chemical reactions.

[0014] 3) Preparation of textured polishing pads: Based on the fractal dimension of the polycrystalline ceramic workpiece surface, the surface of the polishing pad obtained in step 2) is textured. Specifically, for polycrystalline ceramic workpieces with high fractal dimension surfaces, a small-pitch texture is formed on the corresponding polishing pad surface; for polycrystalline ceramic workpieces with low fractal dimension surfaces, a large-pitch texture is formed on the corresponding polishing pad surface. Using this adaptive design, for low-fractal-dimensional polycrystalline ceramic workpieces, whose surface micro-peak heights are relatively low, preparing a large-pitch textured surface (such as a parallel line type or a large grid type texture) can effectively increase the effective contact area during polishing, thereby promoting the chemical reaction at the polishing interface and achieving efficient polishing of the polycrystalline ceramic workpiece. For high-fractal-dimensional polycrystalline ceramic workpieces, whose surface micro-peak scale characteristics are rich, a polishing pad with a finer texture needs to be prepared to adapt to the multi-scale characteristics of the workpiece surface. During polishing, the small-pitch texture on the polishing pad surface can provide more high-stress contact points, increase the effective contact area, promote the activation of micro-peaks on the workpiece surface, and thus facilitate the smooth progress of the chemical reaction at the polishing interface.

[0015] 4) Perform relative motion polishing: In the polishing fluid medium, the polycrystalline ceramic workpiece and the textured polishing disc are made to move relative to each other to complete the polishing process of the polycrystalline ceramic workpiece.

[0016] Ultimately, the mechanical friction and shearing action of the fractal textured micro-protrusions formed on the surface of the polishing pad efficiently removes the reaction products on the workpiece surface, achieving efficient and low-damage precision polishing of the polycrystalline ceramic surface.

[0017] Based on the above scheme, for polycrystalline ceramic workpieces with high fractal dimension surfaces, the corresponding polishing pad surface also possesses a high fractal dimension; for polycrystalline ceramic workpieces with low fractal dimension surfaces, the corresponding polishing pad surface also possesses a low fractal dimension. In practical applications, polishing pad morphologies with different fractal dimensions can be prepared according to the surface roughness of the polycrystalline ceramic workpiece at different polishing stages to increase the effective contact area between the polycrystalline ceramic workpiece and the polishing pad during polishing. For example, in the initial polishing stage, the surface of the polycrystalline ceramic workpiece has many high micro-peaks. At this time, the surface of the polishing pad undergoes fine structuring treatment, resulting in numerous micro-peaks on the polishing pad surface, thereby forming more high-stress contact points in the initial polishing process and increasing the effective contact area during polishing. As the surface roughness of the polycrystalline ceramic workpiece decreases, the micro-peaks on the surface of the polycrystalline ceramic workpiece gradually flatten. At this time, preparing a polishing pad with sparser micro-peaks can form a discrete and uniform Hertzian contact stress field in the polishing contact, ensuring the effective contact area during the polishing process.

[0018] According to the above scheme, in step 2), the surface of the polishing disk with a fractal dimension similar to that of the polycrystalline ceramic workpiece is prepared by grinding with diamond polishing fluid; in step 3), a textured surface is constructed on the polishing disk using laser technology.

[0019] According to the above scheme, the polishing fluid is preferably a water-based polishing fluid, such as deionized water, which is a non-abrasive, non-chemically active polishing fluid. During the polishing process, the triggering of the chemical reaction on the surface of the polycrystalline ceramic workpiece and the removal of the reaction products are both completed independently by the micro-protrusions on the surface of the polishing pad, without the need for abrasive particles or strong acid, strong alkali, or strong oxidizing chemical media, thus improving environmental friendliness.

[0020] According to the above scheme, step 4) uses a polishing device for polishing. The polishing device includes a carrier plate, a swing shaft, a base plate, a swing shaft drive motor, and a polishing disc. The upper end of the polycrystalline ceramic workpiece is fixedly connected to the lower end of the carrier plate. One end of the swing shaft is drivenly connected to the upper end of the carrier plate, and the other end of the swing shaft is drivenly connected to the swing shaft drive motor. The upper surface of the polishing disc contacts the lower surface of the polycrystalline ceramic workpiece, and the lower end of the polishing disc is fixedly connected to the base plate. The swing shaft drive motor drives the swing shaft to move, thereby driving the lower surface of the polycrystalline ceramic workpiece to reciprocate on the upper surface of the polishing disc.

[0021] According to the above scheme, the polycrystalline ceramic workpiece is a magnesium aluminum spinel workpiece or an aluminum nitride ceramic workpiece, and the polishing disc is made of alumina ceramic material.

[0022] According to the above scheme, the range of the high fractal dimension is 1.5 to 2.0, and the range of the low fractal dimension is 1.0 to 1.5.

[0023] According to the above scheme, the texture on the polishing disc is set as a parallel line type or a grid type texture.

[0024] According to the above scheme, the texture on the polishing pad is set as a grid texture; wherein, for polycrystalline ceramic workpieces with a high fractal dimension surface, the grid size of the texture on the surface of the polishing pad is 4mm×4mm; for polycrystalline ceramic workpieces with a low fractal dimension surface, the grid size of the texture on the surface of the polishing pad is 23mm×23mm.

[0025] The stress-catalyzed polishing mechanism described in this invention is as follows: During the stress catalysis process, atoms on the surface of the polycrystalline ceramic workpiece deviate from their steady state under stress, and the chemical bonds between atoms undergo elongation, torsion, and other deformations. The local electronic structure changes accordingly, causing the workpiece surface atoms to tend to recombine with the external medium and enter a new thermodynamic steady state. This effectively promotes the chemical reaction at the contact interface, forming a chemical reaction layer on the workpiece surface. The micro-protrusions on the polishing pad surface serve as the main carrier for the material removal process, enabling effective polishing of the workpiece surface without the need for abrasives. Furthermore, interfacial stress can promote the chemical reaction of the difficult-to-react crystal planes on the polycrystalline ceramic surface, weakening the difference in chemical reaction rates between different crystal planes, thereby alleviating the "orange peel effect" that occurs during the polishing process of polycrystalline ceramics.

[0026] The beneficial effects of this invention are:

[0027] This invention effectively solves the problem of chemical reactions occurring during the polishing process of polycrystalline ceramics, and alleviates the "orange peel effect" caused by differences in the physicochemical properties between different crystal planes on the surface of polished polycrystalline ceramics. Furthermore, water can be used as the polishing fluid, ensuring the environmental friendliness of the polishing process. The method includes the calculation and design of the fractal dimension of the polishing pad surface, laser preparation of the polishing pad surface texture type, increasing the effective contact area between the workpiece and the polishing pad surface during polishing, thereby promoting the efficiency of chemical reactions catalyzed by stress on the workpiece surface, generating a chemical reaction layer on the workpiece surface, and finally achieving efficient and uniform removal of the chemical reaction layer through micro-protrusions on the polishing pad surface. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the present invention, which calculates and fits the surface fractal dimension of polycrystalline ceramics based on the surface morphology and contour lines.

[0029] Figure 2 This is a schematic diagram of the device for stress-catalytic polishing of polycrystalline ceramic workpieces according to the present invention, and a schematic diagram of the micro-peaks of polycrystalline ceramic workpieces activated by contact between micro-peaks of the polishing disc.

[0030] Figure 3 This is a fractal dimension diagram of the surface of the polishing pad used in different polishing stages of this invention;

[0031] Figure 4 This is a fractal dimension diagram obtained by fitting the cross-sectional profile curves of the surface of magnesium aluminum spinel workpieces and aluminum nitride ceramic workpieces in different polishing stages of the present invention.

[0032] Figure 5 These are the actual surface morphologies of magnesium aluminum spinel workpieces and aluminum nitride ceramic workpieces during different polishing stages of this invention.

[0033] Figure 6 The image shows the AFM morphology and grain step height variation of the aluminum nitride ceramic surface after polishing using the polishing method of this invention and conventional chemical mechanical polishing.

[0034] Figure 7 It is a first-principles calculation of the electron density difference, planar electrostatic potential change, IRI isosurface change, and bonding region deformation density map of the aluminum nitride substrate surface after scratching.

[0035] Figure 2 In the middle: 1. Polycrystalline ceramic workpiece; 2. Polishing fluid; 3. Carrying tray; 4. Swing shaft; 5. Polishing disc; 6. Base plate; 7. Swing shaft drive motor. Detailed Implementation

[0036] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, comparative examples and accompanying drawings.

[0037] Example 1

[0038] This embodiment is used to specifically illustrate the calculation process of the fractal dimension of the surface of a polycrystalline ceramic workpiece, and to prepare a polishing disc with micro-peaks and texture on the surface based on the fractal dimension of the polycrystalline ceramic workpiece. In this embodiment, the polycrystalline ceramic workpiece is selected as an aluminum nitride ceramic workpiece, and the polishing disc is selected as an alumina ceramic polishing disc.

[0039] like Figure 1 (a)- Figure 1 As shown in (d), the fractal dimension of the micro-protrusions on the surface of the polycrystalline ceramic workpiece is fitted according to the power density method. Specifically, a white light interferometer is used to measure the surface roughness of different areas of the workpiece, and the surface profile curves of different measurement areas are extracted. The profile curves are leveled and the height values ​​are extracted. The height values ​​are subjected to fast Fourier transform to obtain the frequency and power density. The logarithmic relationship between the frequency and power density is plotted, and the fractal index β is obtained by fitting the logarithmic relationship. The fractal dimension D is then calculated from the fractal index β.

[0040] like Figure 2 (a)- Figure 2As shown in (b), polishing disks with similar fractal dimensions are prepared based on the fractal dimension of the polycrystalline ceramic workpiece surface. For polycrystalline ceramic workpieces with a high fractal dimension ranging from 1.5 to 2.0, high fractal dimension polishing disks are prepared accordingly. Specifically, diamond polishing slurry with an average particle size of 2.5 μm is used for polishing. After polishing, the surface roughness Sa of the polishing disk is approximately 203.2 nm, and the fractal dimension is 1.56. For polycrystalline ceramic workpieces with a low fractal dimension ranging from 1.0 to 1.5, low fractal dimension polishing disks are prepared accordingly. Specifically, diamond polishing slurry with an average particle size of 0.5 μm is used for polishing. After polishing, the average surface roughness Sa of the polishing disk is approximately 48.82 nm, and its fractal dimension is 1.29.

[0041] like Figure 1 (e)- Figure 1 As shown in (f), polishing disks with different surface textures are prepared according to different fractal dimensions of polycrystalline ceramic workpieces. In this embodiment, a grid-type texture is selected, and the textured shape is constructed using laser technology. For polycrystalline ceramic workpieces with a high fractal dimension ranging from 1.5 to 2.0, the grid size of the corresponding polishing disk surface texture is preferably 4mm × 4mm; for polycrystalline ceramic workpieces with a low fractal dimension ranging from 1.0 to 1.5, the grid size of the corresponding polishing disk surface texture is preferably 23mm × 23mm.

[0042] Example 2

[0043] The polishing device used in this embodiment is as follows: Figure 3 As shown on the right, the polishing device includes a carrier disk 3, a swing shaft 4, a polishing disk 5, a base disk 6, and a swing shaft drive motor 7. The upper end of the polycrystalline ceramic workpiece 1 is bonded and fixed to the lower end of the carrier disk 3 with paraffin wax. One end of the swing shaft 4 is drivenly connected to the upper end of the carrier disk 3, and the other end of the swing shaft 4 is drivenly connected to the swing shaft drive motor 7. The upper surface of the polishing disk 5 contacts the lower surface of the polycrystalline ceramic workpiece 1, and the lower end of the polishing disk 5 is bonded and fixed to the base disk 6 with epoxy resin. The swing shaft drive motor 7 drives the swing shaft 4 to move, thereby driving the lower surface of the polycrystalline ceramic workpiece 1 to reciprocate on the upper surface of the polishing disk 5. When the polishing device is working, polishing fluid is added between the polycrystalline ceramic workpiece 1 and the polishing disk 5.

[0044] In this embodiment, the aforementioned polishing apparatus is used to polish magnesium aluminum spinel workpieces and aluminum nitride ceramic workpieces, respectively. The polishing parameters of this apparatus are shown in Table 1. A schematic diagram of atomic activation at the polishing interface is shown below. Figure 3 As shown on the left: After the micro-protrusions on the workpiece surface come into contact with the micro-protrusions on the polishing pad surface, the micro-protrusions on the workpiece surface are activated and react with the polishing liquid to form a reaction layer. Finally, the reaction layer is removed under the mechanical action of the micro-protrusions on the polishing pad, thus completing the polishing of the workpiece.

[0045] Table 1

[0046] Base plate rotation speed 150rpm pressure 2kg Swing speed 2rpm Polishing liquid Deionized water Polishing disc alumina ceramics

[0047] like Figure 4 (a) and Figure 4 (b) shows that in the initial polishing stage, the initial surface roughness Sa value of the magnesium aluminum spinel workpiece is 254.743 nm, and the surface roughness of the aluminum nitride ceramic workpiece is 180.347 nm. According to the power density method fitting, the initial fractal dimensions of the two ceramic surfaces are 1.6038 and 1.5516, which are high fractal dimensions. Therefore, in the initial polishing stage, the polishing disk with a fractal dimension of 1.56 and a surface texture grid size of 4 mm × 4 mm as described in Example 1 is used for polishing.

[0048] like Figure 4 (a1) and Figure 4 As shown in (b1), after 15 minutes of polishing, the surface roughness of polycrystalline magnesium aluminum spinel decreased to 18.3 nm, and the surface roughness of aluminum nitride ceramic decreased to 12.586 nm. According to the power density method, the fractal dimensions are 1.3351 and 1.1998, which are low fractal dimensions. At this time, the polishing disk was replaced with the polishing disk with a fractal dimension of 1.29 and a surface texture grid size of 23 mm × 23 mm as described in Example 1. After 30 minutes of polishing, the surface roughness of aluminum nitride ceramic reached 7.9 nm, and the surface roughness of magnesium aluminum spinel reached 2.0 nm.

[0049] Figure 4 The image shows the surface morphology of the workpiece after polishing, indicating that the surface of the workpiece is smooth and without significant defects.

[0050] Comparative Example 1

[0051] This comparative example uses chemical mechanical polishing (CMP) to polish an aluminum nitride ceramic workpiece with an initial surface roughness of 180.347 nm and an initial surface fractal dimension of 1.5516. The polishing apparatus shown in Example 1 was used, and the polishing parameters are shown in Table 2.

[0052] Table 2

[0053] Base plate rotation speed 80rpm pressure 2kg Swing speed 2rpm Polishing liquid Alkaline silica sol (50nm) Polishing disc Polyurethane polishing pad

[0054] After polishing for 110 minutes using chemical mechanical polishing, the surface morphology of the aluminum nitride ceramic workpiece is as follows: Figure 6 As shown in (b). The surface morphology of the aluminum nitride ceramic workpiece after polishing in Example 2 is as follows. Figure 6As shown in (a). Comparing the surface morphology of the two aluminum nitride ceramic workpieces, the aluminum nitride ceramic workpiece exhibits significant grain step phenomenon after chemical mechanical polishing, with a grain step difference of 139.862 nm. In contrast, the orange peel effect on the surface of the workpiece in Example 2 was significantly alleviated after stress catalytic polishing, with a step difference of 62.321 nm.

[0055] Example 3

[0056] This embodiment investigates the behavior mechanism of the aluminum nitride ceramic workpiece surface deviating from equilibrium state under scratch stress. First-principles calculations and simulations of the scratching process were performed, and the results are as follows: Figure 7 As shown. The chemically stable (10⁻¹⁰) aluminum nitride crystal plane was chosen as the rubbing matrix, and the rubbing behavior was performed by the alumina crystal. In the first-principles molecular dynamics simulation, the K-point was set at the Gamma point, and the SCF self-consistent convergence accuracy was 1*10⁻¹⁰. -5 For the calculation of exchange-related energies, a PBE functional was selected, and the basis sets used in the simulation were DZVP-MOLOPT-GTH type basis sets. The electron density difference at the interface after scratching was analyzed using the generated wavefunction, combined with... Figure 6 IRI isosurface information and deformation density maps reveal significant bonding between the two groups after scratching. Analysis of the chemical bond types shows that significant covalent bonding occurred between the interfacial atoms as scratching progressed. Further analysis of the work function changes during polishing shows a significant decrease in the work function of the alumina groups on the aluminum nitride ceramic surface after scratching, indicating that the surface is more prone to chemical reactions after scratching, providing important conditions for chemical reactions between surface atoms and the external medium. This behavior provides a theoretical basis for the equilibrium shift of atoms under stress during interfacial stress-catalyzed polishing, thereby promoting interfacial chemical reactions.

Claims

1. A stress-catalyzed polishing method for polycrystalline ceramics, characterized in that, Includes the following steps: 1) Obtain the fractal dimension of the polycrystalline ceramic workpiece surface: Collect the surface contour data of the polycrystalline ceramic workpiece, fit the surface contour data using the power spectral density method, and calculate the fractal dimension of the polycrystalline ceramic workpiece surface. 2) Prepare a polishing disk surface with a similar fractal dimension: Based on the fractal dimension of the polycrystalline ceramic workpiece surface calculated in step 1), prepare a polishing disk surface with a similar fractal dimension to the polycrystalline ceramic workpiece surface. 3) Preparation of textured polishing pad: Based on the fractal dimension of the surface of the polycrystalline ceramic workpiece, the surface of the polishing pad obtained in step 2) is textured; wherein, for polycrystalline ceramic workpieces with a high fractal dimension, a small-pitch texture is formed on the surface of the corresponding polishing pad; for polycrystalline ceramic workpieces with a low fractal dimension, a large-pitch texture is formed on the surface of the corresponding polishing pad. 4) Perform relative motion polishing: In the polishing fluid medium, the polycrystalline ceramic workpiece is moved relative to the textured polishing disc to complete the polishing process of the polycrystalline ceramic workpiece.

2. The stress-catalytic polishing method for polycrystalline ceramics according to claim 1, characterized in that, For polycrystalline ceramic workpieces with high fractal dimension surfaces, the corresponding polishing pad surface also has high fractal dimension; for polycrystalline ceramic workpieces with low fractal dimension surfaces, the corresponding polishing pad surface also has low fractal dimension.

3. The stress-catalytic polishing method for polycrystalline ceramics according to claim 2, characterized in that, In step 2), the surface of the polishing disk, which has a similar fractal dimension to the surface of the polycrystalline ceramic workpiece, is prepared by polishing with diamond polishing fluid; in step 3), a textured surface is constructed on the polishing disk using laser technology.

4. The stress-catalytic polishing method for polycrystalline ceramics according to claim 1, characterized in that, The polishing fluid is a non-abrasive, non-chemically active polishing fluid.

5. The stress-catalytic polishing method for polycrystalline ceramics according to claim 4, characterized in that, The polishing solution is deionized water.

6. The stress-catalytic polishing method for polycrystalline ceramics according to claim 1, characterized in that, Step 4) involves polishing using a polishing device, which includes a carrier disk, a swing shaft, a base disk, a swing shaft drive motor, and a polishing disk. The upper end of the polycrystalline ceramic workpiece is fixedly connected to the lower end of the carrier disk. One end of the swing shaft is drivenly connected to the upper end of the carrier disk, and the other end of the swing shaft is drivenly connected to the swing shaft drive motor. The upper surface of the polishing disk contacts the lower surface of the polycrystalline ceramic workpiece, and the lower end of the polishing disk is fixedly connected to the base disk. The swing shaft drive motor drives the swing shaft to move, thereby driving the lower surface of the polycrystalline ceramic workpiece to reciprocate on the upper surface of the polishing disk.

7. The stress-catalytic polishing method for polycrystalline ceramics according to claim 1, characterized in that, The polycrystalline ceramic workpiece is a magnesium aluminum spinel workpiece or an aluminum nitride ceramic workpiece, and the polishing disc is made of alumina ceramic material.

8. The stress-catalytic polishing method for polycrystalline ceramics according to claim 1, characterized in that, The range of the high fractal dimension is 1.5 to 2.0, and the range of the low fractal dimension is 1.0 to 1.

5.

9. The stress-catalytic polishing method for polycrystalline ceramics according to claim 8, characterized in that, The texture on the polishing disc is set as a parallel line type or a grid type texture.

10. The stress-catalytic polishing method for polycrystalline ceramics according to claim 9, characterized in that, The texture on the polishing pad is set as a grid texture; wherein, for polycrystalline ceramic workpieces with a high fractal dimension surface, the grid size of the texture on the surface of the polishing pad is 4mm×4mm; for polycrystalline ceramic workpieces with a low fractal dimension surface, the grid size of the texture on the surface of the polishing pad is 23mm×23mm.

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