A ZrO2 gemstone grinding wheel made of a-SiC ceramic, its preparation method and application

Abstract

The application relates to the technical field of superhard material precision machining, in particular to a ZrO2 gem special a-SiC ceramic grinding wheel, the grinding wheel contains alpha-SiC 70%-80%, a binder 5%-10%, a wetting agent 25%-30% and a binding agent according to the weight percentage; the alpha-SiC is a mixture of 150# and 180#, the binder is 800-mesh water-soluble beta-cyclodextrin powder, and the wetting agent is water-soluble beta-cyclodextrin liquid; the binding agent is made by mixing and ball milling of analytical pure SiO2, Al2O3, KOH, low-melting-point borosilicate glass powder and nanometer ice crystals in a specific ratio; the preparation method comprises the steps of mixing, pressing, drying, sintering and the like, and a three-dimensional mixing machine and a high-temperature sintering furnace are adopted; the grinding wheel is used for ZrO2 gem precision grinding, the grinding parameters are a rotating speed of 45 m / s, an infeed amount of 0.015 mm and a grinding allowance of 0.05 mm, the roughness Ra after grinding is less than or equal to 0.2 microns, and the service life is greater than or equal to 12000 gemstone finishing times; the grinding wheel can solve the problems of the precision, efficiency and surface defects of ZrO2 gem grinding in the prior art, and has excellent comprehensive performance.

Description

Technical Field

[0001] This invention relates to the field of precision machining technology for superhard materials, specifically to an a-SiC ceramic grinding wheel for ZrO2 gemstone grinding, its preparation method, and its application. Background Technology

[0002] The manufacturing process of synthetic gemstones is controllable and less expensive, making them more affordable. Furthermore, synthetic gemstones generally outperform natural gemstones in terms of clarity, color, and size. Product quality can be improved by adjusting process parameters and chemical composition during production. Therefore, synthetic gemstones offer better overall value than natural gemstones.

[0003] Gemstones are geometric shapes composed of various crystal facets. Their brilliance stems primarily from the reflection, refraction, and projection of light through these facets. Therefore, to achieve the best optical effect when light shines on a gemstone, the processing of the boundaries between its facets requires exceptional precision. Different gemstone crystals, due to differences in chemical composition and bonding, exhibit different crystal characteristics, resulting in varying optical orientations and properties.

[0004] Gemstone processing requires that each gemstone be processed according to a specific optical orientation. This is reflected in the requirements for the size, shape, number, and angles between the crystal facets of the gemstone, in order to ensure that it presents the best optical effect.

[0005] In recent years, the global gemstone market has continued to grow. In 2023, the global gemstone and jewelry market was approximately US$372.71 billion, and it is projected to reach US$463.85 billion by 2030, representing a compound annual growth rate of 3.2%. China's jewelry market has also entered a period of rapid development, reaching RMB 820 billion in 2023, a year-on-year increase of 14%. Looking ahead to the next five years, the Chinese jewelry market is expected to continue its growth trend.

[0006] With the increasing demand in the jewelry market, higher requirements are inevitably placed on the gemstone processing industry, which is developing towards "high speed, high precision, and high efficiency." This also presents new requirements and challenges for the abrasive and grinding tool industry.

[0007] Natural ZrO2 exists primarily as monoclinic crystals, mainly as the mineral zircon. Cubic zirconium oxide is extremely rare in nature, but it can be synthesized artificially and is a widely used synthetic gemstone to replace diamond. Cubic zirconium oxide has a high density, with a specific gravity of 5.6 to 6.0, and a hardness of 8.5, lower than diamond but higher than most natural gemstones. Its refractive index is 2.15 to 2.18, slightly lower than diamond's 2.417, but it has an adamantine luster. Its dispersion index is 0.058 to 0.066, exceeding that of diamond. Completely colorless diamonds are almost nonexistent; diamonds usually have a pale yellow tint. However, cubic zirconium oxide can be made to achieve the highest diamond color grade, D.

[0008] ZrO2 is a synthetic gemstone that is more wear-resistant and harder than most natural gemstones. It has high luster and refractive index, almost comparable to natural diamonds, but at a relatively lower price. Due to its hardness, it is more difficult to process.

[0009] While existing technologies disclose grinding wheels for sapphire, both grinding precision and efficiency need improvement. Furthermore, sapphire and ZrO2 are two different gemstones. For example, Chinese patent CN201910463496.9 discloses a grinding wheel for processing single-crystal sapphire. By adding phase change materials, reinforcing materials, and modified polysaccharide binders, it achieves adjustment of the frictional heat distribution at the processing interface, reducing thermal damage to the single-crystal sapphire surface. However, due to the poor cutting force and low grinding efficiency of the grinding wheel in this patent, it cannot improve the precision between the gemstone surfaces. Summary of the Invention

[0010] The purpose of this invention is to provide a ZrO2 gemstone grinding wheel made of a-SiC ceramic, its preparation method and application, in order to solve the problems mentioned in the background art.

[0011] To achieve the above objectives, the present invention provides a ZrO2 gemstone grinding wheel made of a-SiC ceramic, which comprises the following raw materials by weight percentage: 70%-80% a-SiC, 5‰-10‰ binder, 25‰-30‰ wetting agent, and the balance being a binder.

[0012] Preferably, the a-SiC is a mixture of 150# and 180#; the binder has a particle size of 800 mesh.

[0013] Preferably, the binder is water-soluble β-cyclodextrin powder; the wetting agent is water-soluble β-cyclodextrin solution.

[0014] Preferably, the method for preparing the binder includes the following steps:

[0015] S11: Mix the components of the raw materials to obtain a mixture, wherein the raw materials consist of the following components by weight percentage:

[0016] Analytical purity SiO2 51%-61%, analytical purity Al2O3 12%-22%, analytical purity KOH 4%-14%, low melting point borosilicate glass powder 5%-15%, balance is nano-crystal.

[0017] S12: Ball mill the mixture from step S11 for 5.5-6.5 hours, and pass it through an 80-100 mesh sieve to obtain the binder.

[0018] Preferably, the mass percentage of each chemical component in the low-melting-point borosilicate glass powder is as follows: silicon dioxide 71%-74%, aluminum oxide <1.5%, ferric oxide <0.1%, K2O+Na2O <8.5%, boron trioxide 18%-19%, and loss on ignition <0.1%; the refractoriness is 740-760℃.

[0019] On the other hand, the present invention also provides a method for preparing a-SiC ceramic grinding wheel for ZrO2 gemstone polishing, comprising the following steps:

[0020] S21: Add the wetting agent to a-SiC and mix for 18-22 minutes. Then add the binder and adhesive and mix for 25-35 minutes. Pass the mixture through a 12-20 mesh sieve and let it sit at room temperature for ≥72 hours to obtain the mixture.

[0021] S22: The mixture is put into a mold and pressed into shape under a pressure of 15-20MPa for 25-35s. Then it is dried at 80℃-120℃ for ≥52 hours and finally sintered at 910-940℃ for 20-28 hours. After demolding, a-SiC ceramic grinding wheel for ZrO2 gemstone grinding is obtained.

[0022] Preferably, the mixtures described in steps S12 and S21 are mixed using a three-dimensional mixer.

[0023] Preferably, the sintering process in step S22 is carried out in a high-temperature sintering furnace.

[0024] In addition, the present invention also provides an application of a ceramic grinding wheel in the fine grinding of ZrO2 gemstones. The grinding wheel is used for the precision grinding of ZrO2 gemstones, and the roughness Ra after grinding is ≤0.2μm, and the durability is ≥12,000 gemstones per dressing.

[0025] Preferably, the grinding parameters controlled by the a-SiC ceramic grinding wheel are: grinding wheel speed 45m / s, feed rate 0.015mm, and grinding allowance 5 mils, which is 0.05mm.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. This invention optimizes the type and particle size range of the abrasive. a-SiC abrasive has a hexagonal structure, stable crystal structure and chemical properties, and exhibits very high hardness, high thermal conductivity, and a small coefficient of thermal expansion. Compared with traditional silicon carbide abrasives, it can significantly improve the overall grinding effect of ceramic grinding wheels specifically designed for ZrO2 gemstone grinding. Furthermore, abrasives with sharp crystal shapes and narrow particle size ranges are selected to address issues such as scratching and burning in ZrO2 gemstones. This also improves the grinding ratio, grinding efficiency, and reduces the frequency of wheel dressing.

[0028] 2. In the preparation of the grinding wheel described in this invention, a special formula with high density and low binder is used to address the problem of excessive precision tolerance between the surfaces of ZrO2 gemstones during fine grinding. This solves the problem of frequent dressing and low efficiency during ZrO2 gemstone grinding, thereby reducing the dressing frequency and improving the grinding wheel life.

[0029] 3. The ceramic grinding wheel for ZrO2 gemstones described in this invention can ensure that the accuracy between the face and the surface meets the requirements after testing. It has a durability of 12,000 ZrO2 gemstones and can be dressed once. The surface roughness Ra after grinding is ≤0.2μm, and there are no surface defects such as burns, vibration marks, or scratches. Attached Figure Description

[0030] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are explained in detail together with the embodiments of the invention, but do not constitute a limitation thereof.

[0031] Figure 1 These are photos of ZrO2 gemstones after being finely polished using this patented technology.

[0032] Figure 2 These are photographs of ZrO2 gemstones after fine polishing using Examples 1 and 2 of this invention;

[0033] Figure 3 These are photographs of ZrO2 gemstones after fine polishing using Examples 1 and 3 of this invention;

[0034] Figure 4 These are photographs of ZrO2 gemstones after fine polishing using Examples 1 and 4 of this invention. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] The specific materials used in the embodiments, including their models, specifications, and manufacturers, are as follows:

[0037] Analytical grade silicon dioxide, manufactured by Xilong Scientific, has the following main chemical components:

[0038]

[0039] Analytical grade aluminum oxide, manufactured by Sinopharm Chemical Reagent Co., Ltd., has the following main chemical components:

[0040]

[0041] Analytical grade potassium hydroxide, manufactured by Sinopharm Chemical Reagent Co., Ltd., has the following main chemical components:

[0042]

[0043] Nano cryolite, 600 nanometers in size, manufactured by Tianjin Huasheng Chemical Reagent Co., Ltd., has the following main chemical components:

[0044] ≤0.001 ≤0.003 ≤0.01 ≤0.005 ≤0.002

[0045] The binder used in the following examples is water-soluble β-cyclodextrin powder. The viscosity of a 16.8% solution at 25°C should be greater than 1.44E, the solubility at 25°C should be ≥97.6%, and the particle size is 800 mesh. Manufacturer: Shandong Xiwang Sugar Industry Co., Ltd.

[0046] The wetting agent used in the following examples is a water-soluble β-cyclodextrin solution with a specific gravity of 1.09 g / cm3-1.13 g / cm3, manufactured by Shandong Xiwang Sugar Industry Co., Ltd.

[0047] The silicon carbide used in the following examples is a-SiC with particle sizes of 150# and 180#, manufactured by Shanghai Liantian Materials Technology Co., Ltd.

[0048] Example 1

[0049] Example 1 provides a method for preparing a binder for ceramic grinding wheels, the specific steps of which are as follows:

[0050] 1) Mix the components in the raw materials to obtain a mixture, wherein the raw materials are composed of the following components by weight percentage: 56% analytical grade SiO2, 17% analytical grade Al2O3, 9% analytical grade KOH, 10% low melting point borosilicate glass, and 8% nano cryolite;

[0051] 2) The mixture from step 1) is ball-milled for 6 hours and passed through a 100-mesh sieve to obtain the binder.

[0052] In step 1), the characteristics of low-melting-point borosilicate glass powder are as follows:

[0053] a. Chemical composition (mass percentage): Silicon dioxide 71%-74%, Aluminum oxide <1.5%, Ferric oxide <0.1%, K₂O + Na₂O <8.5%, Boron oxide 18%-19%, Loss on ignition <0.1%;

[0054] b. Refractory temperature is 740-760℃.

[0055] The addition of analytically pure SiO2, Al2O3, and KOH increases the purity and strength of the binder. Analytically pure SiO2, the main component, enhances the binder's chemical stability, strength, and grinding sharpness. The introduction of nano-crystals into the binder primarily improves the wear resistance of the a-SiC ceramic grinding wheel specifically designed for ZrO2 gemstone grinding. The use of nano-crystals in the binder, compared to ordinary cryolite, reduces the binder's refractoriness while increasing its reactivity. The introduction of low-melting-point borosilicate glass powder, utilizing its low refractoriness, further increases the binder's strength. With the same grinding wheel hardness, the amount of binder required using this invention is reduced, thus improving abrasive removal efficiency and decreasing the frequency of grinding wheel dressing, effectively preventing the burning of ZrO2 gemstones during fine grinding.

[0056] Example 2

[0057] A special a-SiC ceramic grinding wheel for fine grinding of ZrO2 gemstones. The ceramic grinding wheel described in Example 2 is used for fine grinding of ZrO2 gemstones. By weight percentage, the formulation of the grinding wheel is: 40% a-SiC 150#, 40% a-SiC 180#, 10‰ water-soluble β-cyclodextrin powder, 25‰ water-soluble β-cyclodextrin solution with a specific gravity of 1.12 g / cm3, and 20% binder as described in Example 1.

[0058] The specific steps for preparing the ZrO2 ceramic grinding wheel for gemstone polishing are as follows:

[0059] (1) First, add the wetting agent to the abrasive a-SiC and mix it for 20 minutes using a three-dimensional mixer. Then add the binder and adhesive and mix for 30 minutes. Finally, pass it through a 20-mesh fine sieve and let it sit for 72 hours.

[0060] (2) Press the product using a 400-ton cold press at 17.5 MPa for 30 seconds, then dry it at 100°C for 72 hours; sinter it in a high-temperature sintering furnace at 920°C for 24 hours to obtain the final product.

[0061] Example 3

[0062] A special a-SiC ceramic grinding wheel for fine grinding of ZrO2 gemstones. The ceramic grinding wheel described in Example 3 is used for fine grinding of ZrO2 gemstones. By weight percentage, the formulation of the grinding wheel is: 39% a-SiC 150#, 39% a-SiC 180#, 10‰ water-soluble β-cyclodextrin powder, 27‰ water-soluble β-cyclodextrin solution with a specific gravity of 1.12 g / cm3, and 22% binder as described in Example 2.

[0063] The preparation method of Example 3 is the same as that of Example 2.

[0064] Example 4

[0065] A special a-SiC ceramic grinding wheel for fine grinding of ZrO2 gemstones. The ceramic grinding wheel described in Example 4 is used for fine grinding of ZrO2 gemstones. By weight percentage, the formulation of the grinding wheel is: 38% a-SiC 150#, 38% a-SiC 180#, 10‰ water-soluble β-cyclodextrin powder, 30‰ water-soluble β-cyclodextrin solution with a specific gravity of 1.12 g / cm3, and 24% binder as described in Example 2.

[0066] The preparation method of Example 4 is the same as that of Example 2.

[0067] Application Trial

[0068] The a-SiC ceramic grinding wheels prepared in Examples 2, 3, and 4 were used to finely grind ZrO2 gemstones. The specific fine grinding methods are as follows:

[0069] During fine grinding, the grinding allowance for ZrO2 gemstones is 5 microns. The surface roughness Ra before fine grinding is 1.0 μm, and the surface roughness requirement for ZrO2 gemstones after grinding is Ra≤0.2 μm. The grinding wheel speed is 45 m / s, and the grinding wheel feed rate is 0.015 mm. On average, the ZrO2 gemstones are dressed once after grinding 9000-10000 pieces. The straightness between the surfaces of the ZrO2 gemstones after fine grinding is required to be less than 0.01 mm.

[0070] During grinding, the average grain diameter of ZrO2 gemstones is 13mm to 15mm. Note: For fine grinding of ZrO2 gemstones, refer to the standard "Technical Data Handbook for Gemstone Identification, Processing and Application".

[0071] Test results

[0072] Currently, ZrO2 gemstone processing manufacturers use conventional grinding wheels for fine grinding. These grinding wheels require frequent dressing, have low durability and short service life, low grinding efficiency, and produce excessive straightness between the ground surface and the finished surface. Sometimes, scratches or burns may also occur.

[0073] 1. Compared with the existing technology for grinding ZrO2 gemstones, the grinding wheels made in Examples 1 and 2 were tested, and the hardness values ​​of the three tests in the 28-grit chamber (hardness test level) were 4.2, 4.3, and 4.2, respectively.

[0074] Through actual grinding testing of the grinding wheel (the tested wheel specification was P-305x50x65), the surface roughness of the ZrO2 gemstone met the requirements, but the straightness between the surfaces exceeded the tolerance (see the photo of the ZrO2 gemstone after grinding). Figure 2 As shown in the figure, the specific test results are as follows: the straightness between surfaces is 0.018mm, the durability is 10,000 gemstones for one dressing, the surface roughness Ra after grinding is 0.2μm, and the workpiece surface has no surface defects such as burns, vibration marks, or scratches.

[0075] 2. Compared with the existing technology for grinding ZrO2 gemstones, the grinding wheels made in Examples 1 and 3, after testing, showed hardness values ​​of 3.8, 3.8 and 3.9 in three tests in the 28-grit chamber (hardness test level).

[0076] Through actual grinding testing of the grinding wheel (the tested wheel specification was P-305x50x65), the surface roughness and straightness between surfaces of the ZrO2 gemstone both met the requirements (photos of the ground ZrO2 gemstone are shown below). Figure 3 As shown in the figure, the specific test results are as follows: the straightness between surfaces is 0.007mm, the durability is 12,000 gemstones for one dressing, the surface roughness Ra after grinding is 0.16μm, and the workpiece surface has no surface defects such as burns, vibration marks, or scratches.

[0077] 3. Compared with the existing technology for grinding ZrO2 gemstones, the grinding wheels made in Examples 1 and 4 were tested, and the hardness values ​​of the three tests in the 28-grit chamber (hardness test level) were 3.5, 3.6, and 3.5, respectively.

[0078] Through actual grinding testing of the grinding wheel (the tested wheel specification was P-305x50x65), the surface roughness and straightness between surfaces of the ZrO2 gemstone both met the requirements (photos of the ground ZrO2 gemstone are shown below). Figure 4 As shown in the figure, the specific test results are as follows: the straightness between the surfaces is 0.006mm, the durability is 8000 gemstones per dressing, the surface roughness Ra after grinding is 0.12μm, and the workpiece surface has slight burns and vibration marks.

[0079] When grinding ZrO2 gemstones using the grinding wheel described in this invention, the service life of the grinding wheel described in this invention can be increased by 65% ​​compared with conventional grinding wheels for ZrO2 gemstones, while still meeting the grinding requirements.

[0080] The test results show that the ceramic binder prepared by this invention can be used in ceramic grinding wheels for fine grinding of ZrO2 gemstones. When the ceramic grinding wheel is used for fine grinding of ZrO2 gemstones, it can pass the actual grinding test and ultimately achieve the requirements for roughness and straightness between surfaces of ZrO2 gemstones. The durability is 12,000 workpieces that need to be dressed once, and the roughness Ra after grinding is 0.16μm. Moreover, the workpiece surface is free of surface defects such as burns, vibration marks, and scratches, and has a long service life.

[0081] This invention provides the application of the ZrO2 gemstone fine grinding ceramic grinding wheel in the fine grinding process of ZrO2 gemstones. Specifically, the ZrO2 gemstone fine grinding ceramic grinding wheel is used in the fine grinding process of ZrO2 gemstones.

[0082] The longer the service life of the grinding wheel, the better, and the less frequent the dressing, the better. This requires the binder to not only have high strength but also good sharpness, while increasing the binding force of the binder on the abrasive. Therefore, the binder needs to be improved and enhanced. Based on this, the ZrO2 gemstone fine grinding ceramic grinding wheel of this invention improves the performance of the binder by introducing analytical pure substances instead of pure natural minerals and low melting point glass materials, based on the existing binder composition, ratio and grinding wheel preparation process.

[0083] Low-melting-point KOH and borosilicate glass powder effectively reduce the refractoriness of the binder while increasing the melt flowability of the binder during sintering. This allows the binder to more fully coat the abrasive. At the same time, without changing the compound ratio in the binder, it also increases the sharpness and strength of the grinding wheel, thereby reducing the dressing frequency and increasing the service life of the grinding wheel. It also solves the problem of foaming and black core in fine-grained, high-hardness silicon carbide ceramic grinding wheels.

[0084] In addition, based on the existing ZrO2 gemstone grinding ceramic grinding wheel special binder, the present invention introduces nano-crystal stone, which can make the binder melt and flow better, and significantly improve the grinding ratio of the prepared ZrO2 gemstone grinding ceramic grinding wheel.

[0085] β-Cyclodextrin is introduced as a binder and wetting agent because it has excellent chemical stability, solubility and inclusion properties. This allows for better wetting of the abrasive and better encapsulation of the abrasive by the binder, thereby improving the strength of the prepared ZrO2 ceramic grinding wheel for gemstone grinding.

[0086] The grinding wheel described in this invention is manufactured using a three-dimensional mixing and isostatic pressing method. This method ensures the best grinding performance of the grinding wheel while improving the stability of its quality.

[0087] The ZrO2 gemstone-specific a-SiC ceramic grinding wheel of the present invention, its preparation method, and its application have the following effects:

[0088] I. Beneficial effects of binders

[0089] 1. Improved purity and strength

[0090] The addition of analytically pure SiO2, Al2O3, and KOH improved the purity and strength of the binder. SiO2, as the main component of the binder, increased its chemical stability, strength, and grinding sharpness. This helps the binder better hold the abrasive grains during grinding, maintaining a stable working state and improving grinding efficiency and quality.

[0091] 2. Enhanced wear resistance

[0092] The introduction of nano-crystals into the binder effectively improves the wear resistance of ZrO2-based α-SiC ceramic grinding wheels specifically designed for gemstone grinding. Compared to ordinary cryolite, nano-crystals reduce the refractoriness of the binder while increasing its reactivity. The lower refractoriness allows the binder to more easily form a favorable microstructure during sintering, while the higher reactivity promotes the bonding between the binder and the abrasive grains, thereby improving the overall wear resistance of the grinding wheel and extending its service life.

[0093] 3. Increased bond strength

[0094] By introducing low-melting-point borosilicate glass powder, its low refractoriness is utilized to increase the strength of the binder. Under the same grinding wheel hardness requirements, grinding wheels using this binder require a smaller amount of binder. This means more space is available for the abrasive grains, improving their grinding efficiency. Simultaneously, it reduces the frequency of grinding wheel dressing, lowers production costs, and effectively reduces the risk of burning ZrO2 gemstones during fine grinding.

[0095] II. Beneficial Effects of Grinding Wheel Formulation

[0096] 1. Advantages of abrasive grain matching

[0097] By using a mixture of two different abrasive grains, α-SiC150# and α-SiC180#, the advantages of different grit sizes can be fully utilized. The coarser 150# abrasive grains can quickly remove larger allowances, improving grinding efficiency; while the finer 180# abrasive grains can perform fine grinding on the gemstone surface, ensuring the surface quality after grinding. This combination allows the grinding wheel to ensure both high grinding efficiency and meet the requirements for surface roughness and straightness when grinding ZrO2 gemstones.

[0098] 2. Selection of adhesives and wetting agents

[0099] Using water-soluble β-cyclodextrin powder as a binder and corresponding wetting agent facilitates uniform mixing among the abrasive grains, binder, and adhesive. Its water solubility allows for better dispersion during mixing, forming a homogeneous mixture and ensuring the overall stability of the grinding wheel's performance. Simultaneously, the excellent binding properties of β-cyclodextrin powder ensure that the abrasive grains are firmly fixed in the binder, preventing premature detachment and improving the grinding wheel's durability.

[0100] III. Beneficial Effects of Preparation Method

[0101] 1. Mixing process

[0102] Using a three-dimensional mixer to mix materials ensures thorough and uniform mixing of abrasives, binders, and adhesives. Compared to ordinary mixing methods, the three-dimensional mixer allows materials to move in multiple directions, avoiding localized aggregation and uneven distribution, thus ensuring the consistency of performance across all parts of the grinding wheel.

[0103] 2. Pressing and sintering process

[0104] Holding the material under appropriate pressure and sintering it at a specific temperature helps to form a dense and uniform microstructure in the grinding wheel. Appropriate pressure allows the materials to bond tightly, improving the strength of the grinding wheel; while precisely controlled sintering temperature and time allow the binder to fully function, enabling the grinding wheel to reach its optimal performance state. For example, the parameters such as pressure, drying temperature, and sintering temperature used in the examples have been experimentally verified to produce high-quality grinding wheels that meet the requirements for fine grinding of ZrO2 gemstones.

[0105] IV. Beneficial Effects in Application

[0106] 1. Improved surface quality

[0107] Actual grinding tests show that the grinding wheel prepared according to this invention can effectively meet the surface roughness requirements of ZrO2 gemstones during fine grinding, and the workpiece surface is free of surface defects such as burns, vibration marks, and scratches. For example, in Example 3, the surface roughness Ra after grinding reached 0.16 μm, which indicates that the grinding wheel can perform fine processing on the gemstone surface during the grinding process, ensuring the surface quality of the gemstone.

[0108] 2. Improved straightness

[0109] Regarding the straightness between surfaces, some embodiments can meet the requirement of less than 0.01 mm. For example, the straightness between surfaces in Embodiment 3 reaches 0.007 mm, and in Embodiment 4 it reaches 0.006 mm. This indicates that the grinding wheel of the present invention can maintain good stability and accuracy during grinding, effectively solving the problem of excessive straightness in the prior art.

[0110] 3. Improved durability

[0111] Compared with conventional grinding wheels in the prior art, the grinding wheel of the present invention has significantly improved durability. For example, the grinding wheel of Example 3 has a durability of 12,000 gemstones to be dressed once, and its overall service life can be increased by 65%. This means that in actual production, using the grinding wheel of the present invention can reduce the number of grinding wheel replacements, reduce production costs, and improve production efficiency.

[0112] In summary, through optimization of the binder formulation, rational matching of the grinding wheel formulation, and precise control of the preparation method, the ZrO2 gemstone-specific α-SiC ceramic grinding wheel prepared by this invention has achieved significant beneficial effects in terms of surface quality, straightness, and durability, and has good market application prospects.

[0113] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A ZrO2 gemstone grinding wheel made of a-SiC ceramic, characterized in that, By weight percentage, it includes the following raw materials: 70%-80% a-SiC, 5‰-10‰ binder, 25‰-30‰ wetting agent, and the balance is binder; The a-SiC is a mixture of 150# and 180#; the binder has a particle size of 800 mesh. The binder is water-soluble β-cyclodextrin powder; the wetting agent is water-soluble β-cyclodextrin solution; The preparation method of the binder includes the following steps: S11: Mix the components of the raw materials to obtain a mixture, wherein the raw materials consist of the following components by weight percentage: Analytical purity SiO2 51%-61%, analytical purity Al2O3 12%-22%, analytical purity KOH 4%-14%, low melting point borosilicate glass powder 5%-15%, balance is nano cryolite; S12: Ball mill the mixture from step S11 for 5.5-6.5 hours, and pass it through an 80-100 mesh sieve to obtain the binder; The mass percentages of each chemical component in the low-melting-point borosilicate glass powder are as follows: silicon dioxide 71%-74%, aluminum oxide <1.5%, ferric oxide <0.1%, K2O+Na2O <8.5%, boron oxide 18%-19%, and loss on ignition <0.1%; the refractoriness is 740-760℃.

2. A method for preparing a-SiC ceramic grinding wheel for ZrO2 gemstone polishing as described in claim 1, characterized in that, Includes the following steps: S21: Add the wetting agent to a-SiC, mix and stir for 18-22 minutes, then add the binder and adhesive, mix and stir for 25-35 minutes, pass through a 12-20 mesh sieve, and let it sit at room temperature for ≥72 hours to obtain the mixture; S22: The mixture is put into the mold and pressed into shape under a pressure of 15-20MPa for 25-35s. Then it is dried at 80℃-120℃ for ≥52 hours and finally sintered at 910-940℃ for 20-28 hours. After demolding, a-SiC ceramic grinding wheel for ZrO2 gemstone grinding is obtained.

3. The method for preparing the ZrO2 gemstone-specific a-SiC ceramic grinding wheel according to claim 2, characterized in that, The mixtures described in steps S12 and S21 are mixed using a three-dimensional mixer.

4. The method for preparing the ZrO2 gemstone-specific a-SiC ceramic grinding wheel according to claim 2, characterized in that, The sintering process described in step S22 is carried out in a high-temperature sintering furnace.

5. An application of a ceramic grinding wheel as described in any one of claims 1-4 in the fine grinding of ZrO2 gemstones, characterized in that: The grinding wheel is used for precision grinding of ZrO2 gemstones, with a surface roughness Ra≤0.2μm after grinding and a durability of ≥12,000 ZrO2 gemstones per dressing cycle.

6. The application of the a-SiC ceramic grinding wheel according to claim 5 in ZrO2 gemstones, characterized in that: The grinding parameters controlled by the a-SiC ceramic grinding wheel are: grinding wheel speed 45m / s, feed rate 0.015mm, and grinding allowance 5 mils, which is 0.05mm.

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