A high-precision and high-efficiency polishing method for hard and brittle ceramic materials

Abstract

A high-precision, high-efficiency polishing method for hard and brittle ceramic materials belongs to the field of precision / ultra-precision machining technology. This invention addresses the difficulties in achieving a balance between efficiency and precision in existing high-precision machining of hard and brittle ceramic materials, as well as the long production cycle. The method involves first preparing a photocatalytic nanopolishing liquid, then using the photocatalytic nanopolishing liquid to polish the hard and brittle ceramic material under ultraviolet light. This method is used for high-precision, high-efficiency polishing of hard and brittle ceramic materials.

Description

Technical Field

[0001] The invention belongs to the technical field of precision / ultra-precision machining. Background Art

[0002] In recent years, with the continuous development of advanced optoelectronic technologies, the requirements for precision optical components have continued to increase, primarily reflecting demands for larger apertures, lighter weight, aspheric surfaces, and superior physical properties. A series of typical hard and brittle ceramic materials, represented by silicon carbide, fused quartz, and spinel, are widely used in cutting-edge defense and civilian technologies, including large astronomical telescopes, infrared optical systems, laser fusion devices, and the semiconductor industry, due to their excellent properties such as high hardness, low thermal expansion coefficient, high temperature resistance, and corrosion resistance.

[0003] Although the material properties of such hard and brittle ceramics make them popular among relevant practitioners, they have ultra-high hardness and strong chemical inertness, and their compressive strength is much greater than their bending strength, which makes them significantly brittle, making it extremely difficult to process hard and brittle ceramics with high precision and high efficiency. Existing process technologies make it difficult to achieve a balance between efficiency and precision, that is, it is difficult to achieve excellent production efficiency while meeting the target precision requirements. This results in a production cycle of such high-precision components lasting several weeks or even months, seriously affecting the time and economic cost of research and development of related components. At present, the manufacturing and processing technology of hard and brittle ceramic components has become one of the key factors restricting the development of optoelectronic technology. Therefore, achieving high-precision and efficient processing of hard and brittle ceramics is of great significance to the development of optoelectronic technology in my country. Summary of the Invention

[0004] The present invention aims to solve the problem that the existing high-precision processing of hard and brittle ceramic materials is difficult to achieve a balance between efficiency and precision and has a long production cycle, and further provides a high-precision and high-efficiency polishing method for hard and brittle ceramic materials.

[0005] A high-precision and high-efficiency polishing method for hard and brittle ceramic materials is carried out in the following steps:

[0006] Nano-abrasive particles, nano-photocatalytic particles, an oxidant, nano-graphene oxide, a dispersant and deionized water are mixed and the pH value is adjusted to obtain a photocatalytic nano-polishing liquid; under ultraviolet light irradiation, the photocatalytic nano-polishing liquid is used to polish hard and brittle ceramic materials, thereby completing a high-precision and high-efficiency polishing method for hard and brittle ceramic materials.

[0007] The beneficial effects of the present invention are:

[0008] (1) This method combines abrasive removal with photocatalytic chemical softening and nanomaterial lubrication. The synergistic effect of the three enables high-quality removal of hard and brittle ceramic materials, achieving a balance between efficiency and precision. Compared with traditional free abrasive polishing, this method can significantly improve the material removal rate and surface quality of the polishing process.

[0009] (2) The materials used in this method are non-toxic and harmless, and are significantly sustainable and environmentally friendly.

[0010] (3) This method has low equipment requirements and only requires the introduction of an ultraviolet light source. The materials used are low in cost, so the overall cost of the method is low and the economic controllability is strong.

[0011] (4) This method can be applied to a variety of processing scenarios, including sub-aperture shaping processing and full-aperture flattening processing, and has significant application universality.

[0012] Figures in the specification

[0013] Figure 1 Schematic diagram of high-precision and high-efficiency polishing of hard and brittle ceramic materials according to the present invention, 1 is a sub-aperture polishing disc, 2 is a polishing pad, 3 is a hard and brittle ceramic material, 4 is a clamping workbench, 5 is an ultraviolet light source, and 6 is a photocatalytic nano-polishing liquid;

[0014] Figure 2 Schematic diagram comparing the surface roughness and material removal rate of silicon carbide ceramic materials after high-precision polishing in Example and Comparative Examples 1 to 3;

[0015] Figure 3 Schematic diagrams of the surface morphology of silicon carbide ceramic materials after high-precision polishing of Example and Comparative Examples 1 to 3, (a) is Comparative Example 1, (b) is Comparative Example 2, (c) is Comparative Example 3, and (d) is Example;

[0016] Figure 4 Schematic diagram of the grid trajectory in step 2 of the embodiment. DETAILED DESCRIPTION

[0017] Specific implementation method 1, combined with Figure 1 Specific description: This embodiment is a high-precision and high-efficiency polishing method for hard and brittle ceramic materials, which is carried out in the following steps:

[0018] Nano-abrasive particles, nano-photocatalytic particles, an oxidant, nano-graphene oxide, a dispersant and deionized water are mixed and the pH value is adjusted to obtain a photocatalytic nano-polishing liquid; under ultraviolet light irradiation, the photocatalytic nano-polishing liquid is used to polish hard and brittle ceramic materials, thereby completing a high-precision and high-efficiency polishing method for hard and brittle ceramic materials.

[0019] The beneficial effects of this embodiment are:

[0020] (1) This method combines abrasive removal with photocatalytic chemical softening and nanomaterial lubrication. The synergistic effect of the three enables high-quality removal of hard and brittle ceramic materials, achieving a balance between efficiency and precision. Compared with traditional free abrasive polishing, this method can significantly improve the material removal rate and surface quality of the polishing process.

[0021] (2) The materials used in this method are non-toxic and harmless, and are significantly sustainable and environmentally friendly.

[0022] (3) This method has low equipment requirements and only requires the introduction of an ultraviolet light source. The materials used are low in cost, so the overall cost of the method is low and the economic controllability is strong.

[0023] (4) This method can be applied to a variety of processing scenarios, including sub-aperture shaping processing and full-aperture flattening processing, and has significant application universality.

[0024] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that: 1% to 5% of nano-abrasive particles, 0.1% to 2% of nano-photocatalytic particles, 2% to 10% of an oxidant, 0.1% to 0.5% of nano-graphene oxide, 0.1% to 0.8% of a dispersant, and the balance deionized water are weighed and mixed, and then a pH adjuster is added to a pH of 3 to 11. Finally, the mixture is uniformly mixed by mechanical stirring and ultrasonic dispersion in sequence to obtain a photocatalytic nano-polishing liquid. Other aspects are the same as specific embodiment 1.

[0025] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that the average particle size of the nano-abrasive particles is 50nm to 500nm; the average particle size of the nano-photocatalytic particles is 10nm to 100nm. Other aspects are the same as specific embodiment 1 or 2.

[0026] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the nano-abrasive particles are one or a combination of diamond, silicon oxide, silicon carbide, aluminum oxide, and cerium oxide. Other aspects are the same as specific embodiments 1 to 3.

[0027] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the nano-photocatalytic particles are one or a combination of titanium dioxide, cerium oxide, zinc oxide and chromium oxide. Other aspects are the same as specific embodiments 1 to 4.

[0028] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that the oxidant is one or a combination of hydrogen peroxide, potassium permanganate and potassium persulfate. Other aspects are the same as specific embodiments 1 to 5.

[0029] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that the nanographene oxide sheet has a diameter of 0.2 μm to 50 μm, 1 to 2 layers, and a single layer thickness of 0.3 nm to 3 nm. Other aspects are the same as specific embodiments 1 to 6.

[0030] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that the dispersant is one or a combination of sodium polyacrylate, sodium hexametaphosphate, sodium lauryl sulfate, and sodium dodecylbenzene sulfonate. Other aspects are the same as specific embodiments 1 to 7.

[0031] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the pH adjuster is one or a combination of potassium hydroxide, phosphoric acid, ammonia water, triethanolamine, and aminomethyl propanol. Other aspects are the same as specific embodiments 1 to 8.

[0032] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that: when the ultraviolet light wavelength is 300nm to 400nm and the ultraviolet light intensity is 1000mW / cm 2 ~2000mW / cm 2 Under the conditions of a sub-aperture polishing disk speed of 200 rpm to 1200 rpm, a pressure of 35 kPa to 65 kPa, and a feed speed of 0.5 mm / s to 1.5 mm / s, the hard and brittle ceramic material is polished 1 to 2 times using a polishing pad and a photocatalytic nano-polishing liquid; under the conditions of an ultraviolet light wavelength of 300 nm to 400 nm and an ultraviolet light intensity of 1000 mW / cm 2 ~2000mW / cm 2 , polishing the hard and brittle ceramic material using a polishing pad and a photocatalytic nano-polishing liquid at a full-aperture polishing disk speed of 60 rpm to 120 rpm and a pressure of 35 kPa to 65 kPa for 10 to 20 minutes; the photocatalytic nano-polishing liquid is supplied at a flow rate of 0.2 L / min to 0.5 L / min. Other aspects are the same as in Specific Embodiments 1 to 9.

[0033] The following examples are used to verify the beneficial effects of the present invention:

[0034] Example:

[0035] A high-precision and high-efficiency polishing method for hard and brittle ceramic materials is carried out in the following steps:

[0036] 1. Preparation of photocatalytic nano-polishing liquid:

[0037] 1% of nano-diamond abrasive particles, 0.2% of nano-photocatalytic particles, 5% of an oxidant, 0.2% of nano-graphene oxide, 0.2% of a dispersant, and the balance of deionized water were weighed and mixed by mass, and then a pH adjuster was added to a pH of 3.5, and finally the mixture was uniformly mixed by mechanical stirring and ultrasonic dispersion in sequence to obtain a photocatalytic nano-polishing liquid;

[0038] 2. Silicon carbide precision polishing:

[0039] When the UV wavelength is 365nm and the UV intensity is 1000mW / cm 2 Under the conditions of a sub-aperture polishing disk speed of 600 rpm, a pressure of 65 kPa and a feed speed of 1 mm / s, silicon carbide was polished once using a polishing pad and a photocatalytic nano-polishing liquid (polishing time was 12 min), then immersed in deionized water for ultrasonic cleaning for 20 min, and then the surface of the workpiece was gently wiped with a dust-free cloth. Finally, it was blown dry with a nitrogen flow to obtain a high-precision polished silicon carbide ceramic material.

[0040] The average particle size of the nano-diamond abrasive particles described in step 1 is 200 nm; the average particle size of the nano-photocatalytic particles described in step 1 is 60 nm.

[0041] The nano-photocatalytic particles described in step 1 are titanium dioxide.

[0042] The oxidant in step 1 is 5% by mass of hydrogen peroxide.

[0043] The nano graphene oxide described in step 1 is industrial-grade graphene oxide, with a sheet diameter of 10 μm to 50 μm, 1 to 2 layers, and a single thickness of 1 nm to 3 nm.

[0044] The dispersant described in step one is sodium polyacrylate.

[0045] The pH regulator described in step 1 is phosphoric acid with a mass percentage of 0.35 mol / L.

[0046] The silicon carbide described in step 2 is a pressure-sintered silicon carbide ceramic piece of 60 mm×60 mm×2 mm, and the surface roughness after rough polishing is about 100 nm.

[0047] The polishing pad described in step 2 is an IC1000 composite polyurethane polishing pad; the sub-aperture polishing disk described in step 2, that is, the polishing disk size is smaller than the size of the workpiece to be polished. In this embodiment, a center liquid supply polishing disk with a diameter of 20 mm is specifically selected; the photocatalytic nano-polishing liquid described in step 2 is evenly supplied to the processing area from the center liquid supply polishing disk through a peristaltic pump, and the supply flow rate is 0.3 L / min.

[0048] Step 2: During the polishing process, the machine moves along a grid track and processes on an area of 26×26mm with a grid spacing of 1mm. Figure 4 As shown, Figure 4 This is a schematic diagram of the grid trajectory in step 2 of the embodiment;

[0049] In step 2, a polishing experiment was conducted using a 6-DOF industrial robot from patent application number 201510506108.2, entitled "An Overconstrained High-Strength Robot with Trisymmetric Kinematic Performance," in combination with a polishing device from patent application number 201710708784.7, entitled "Large-Aperture Aspheric Robot Eccentric Planetary Polishing Device."

[0050] The workpiece mass before and after processing was measured using a ZA805AS precision electronic balance to calculate the material removal rate during the polishing process; the surface morphology and surface roughness after processing were measured using a white light interferometer (Bruker, ContourGT, USA). The surface roughness Sa measured in Example 1 was 10.2792 nm, and the material removal rate was 0.03564 mm 3 / min.

[0051] Comparative Example 1: Polishing Silicon Carbide Ceramic with Conventional Free Diamond Abrasives: This comparative example differs from the example in that, in step 1, 1% by mass of nanodiamond abrasive particles, 0.2% of a dispersant, and the balance of deionized water are weighed and mixed, followed by the addition of a pH adjuster to a pH of 3.5. Finally, the mixture is uniformly mixed by mechanical stirring and ultrasonic dispersion, yielding a photocatalytic nanopolishing solution. Ultraviolet light irradiation is omitted in step 2. All other steps are the same as those in the example.

[0052] The workpiece mass before and after processing was measured using a ZA805AS precision electronic balance to calculate the material removal rate during the polishing process; the surface morphology and surface roughness after processing were measured using a white light interferometer (Bruker, ContourGT, USA). The surface roughness Sa measured in Comparative Example 1 was 30.8084 nm, and the material removal rate was 0.02347 mm 3 / min.

[0053] Comparative Example 2: Photocatalytically Assisted Polishing of Silicon Carbide Ceramics with Free Diamond Abrasives: This comparative example differs from the example in that, in step 1, 1% nanodiamond abrasive, 0.2% nanophotocatalytic particles, 5% oxidant, 0.2% dispersant, and the balance deionized water are weighed and mixed, respectively, followed by addition of a pH adjuster to a pH of 3.5. Finally, mechanical stirring and ultrasonic dispersion are sequentially performed to achieve uniform mixing, yielding a photocatalytic nanopolishing solution. Other steps are the same as those in the example.

[0054] The workpiece mass before and after processing was measured using a ZA805AS precision electronic balance to calculate the material removal rate during the polishing process; the surface morphology and surface roughness after processing were measured using a white light interferometer (Bruker, ContourGT, USA). The surface roughness Sa measured in Comparative Example 2 was 24.8189 nm, and the material removal rate was 0.02497 mm 3 / min.

[0055] Comparative Example 3: Polishing of Silicon Carbide Ceramics with Nano-Graphene Oxide-Assisted Free Diamond Abrasives: This comparative example differs from the example in that, in step 1, 1% nano-diamond abrasive, 0.2% nano-graphene oxide, 0.2% dispersant, and the balance deionized water are weighed and mixed, followed by the addition of a pH adjuster to a pH of 3.5. Finally, the mixture is uniformly mixed by mechanical stirring and ultrasonic dispersion, yielding a photocatalytic nano-polishing solution. Ultraviolet light irradiation is omitted in step 2. All other steps are the same as those in the example.

[0056] The workpiece mass before and after processing was measured using a ZA805AS precision electronic balance to calculate the material removal rate during the polishing process; the surface morphology and surface roughness after processing were measured using a white light interferometer (Bruker, ContourGT, USA). The surface roughness Sa measured in Comparative Example 3 was 22.524 nm, and the material removal rate was 0.0313 mm 3 / min.

[0057] Figure 2 Schematic diagram comparing the surface roughness and material removal rate of silicon carbide ceramic materials after high-precision polishing in Examples and Comparative Examples 1 to 3; from the comparative analysis of the figures, it is found that the surface roughness and material removal rate obtained by using the traditional free diamond abrasive polishing method, photocatalysis-assisted free diamond abrasive polishing, and nano-graphene oxide-assisted free diamond abrasive polishing are inferior to the process and polishing liquid proposed in the examples.

[0058] Figure 3 Schematic diagrams of the surface morphology of silicon carbide ceramic materials after high-precision polishing in Examples and Comparative Examples 1 to 3, (a) for Comparative Example 1, (b) for Comparative Example 2, (c) for Comparative Example 3, and (d) for Examples. As can be seen from the figures, polishing the silicon carbide ceramic using traditional free diamond abrasives results in large high-frequency errors and numerous surface defects, such as deep pits and grooves. Polishing using photocatalytically assisted free diamond abrasives and nano-graphene oxide-assisted free diamond abrasives improves surface finish, but deep scratches still exist and the surface quality is less than ideal. Polishing the silicon carbide ceramic using the method of the Example results in a smoother, smoother surface with excellent surface quality.

Claims

1. A high-precision and high-efficiency polishing method for hard and brittle ceramic materials, characterized in that It is carried out in the following steps: 1% to 5% of nano-abrasive particles, 0.1% to 0.2% of nano-photocatalytic particles, 5% to 10% of an oxidant, 0.1% to 0.2% of nano-graphene oxide, 0.1% to 0.8% of a dispersant, and the balance of deionized water are weighed and mixed by mass percentage, and then a pH adjuster is added to a pH of 3 to 11, and finally the mixture is uniformly mixed by mechanical stirring and ultrasonic dispersion in sequence to obtain a photocatalytic nano-polishing liquid; the average particle size of the nano-abrasive particles is 50 nm to 500 nm; the average particle size of the nano-photocatalytic particles is 10 nm to 100 nm; the sheet diameter of the nano-graphene oxide is 0.2 μm to 50 μm, the number of layers is 1 to 2, and the thickness of a single layer is 0.3 nm to 3 nm; the nano-abrasive particles are diamonds; and the oxidant is hydrogen peroxide; When the UV wavelength is 300nm~400nm and the UV intensity is 1000mW / cm 2 ~2000mW / cm 2 Under the conditions of a sub-aperture polishing disc speed of 200 rpm to 1200 rpm, a pressure of 35 kPa to 65 kPa, and a feed speed of 0.5 mm / s to 1.5 mm / s, a polishing pad and a photocatalytic nano-polishing liquid are used to polish the hard and brittle ceramic material once or twice, thereby completing a high-precision and high-efficiency polishing method for the hard and brittle ceramic material; When the UV wavelength is 300nm~400nm and the UV intensity is 1000mW / cm 2 ~2000mW / cm 2 2. Under the conditions of a full-aperture polishing disc speed of 60rpm~120rpm and a pressure of 35kPa~65kPa, a polishing pad and a photocatalytic nano-polishing liquid are used to polish hard and brittle ceramic materials for 10min~20min, thereby completing a high-precision and high-efficiency polishing method for hard and brittle ceramic materials; The supply flow rate of the photocatalytic nano-polishing liquid is 0.2L / min~0.5L / min.

2. A high-precision and high-efficiency polishing method for hard and brittle ceramic materials according to claim 1, characterized in that The nanometer photocatalytic particles are one of titanium dioxide, cerium oxide, zinc oxide and chromium oxide, or a combination of several of them.

3. A high-precision and high-efficiency polishing method for hard and brittle ceramic materials according to claim 1, characterized in that The dispersant is one of sodium polyacrylate, sodium hexametaphosphate, sodium lauryl sulfate and sodium dodecylbenzene sulfonate, or a combination of several of them.

4. A high-precision and high-efficiency polishing method for hard and brittle ceramic materials according to claim 1, characterized in that The pH regulator is one of potassium hydroxide, phosphoric acid, ammonia water, triethanolamine and aminomethyl propanol, or a combination of several of them.

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