Polishing solution for precise polishing of large-size fused quartz glass and preparation method of polishing solution

Abstract

The invention discloses a polishing solution for precise polishing of large-size fused quartz glass and a preparation method of the polishing solution. The precise polishing solution is prepared from the following raw materials in parts by weight: 0.5 to 12 parts of cerium oxide powder, 0.05 to 2.4 parts of nano hexagonal boron nitride, 0.5 to 1.2 parts of dispersing agent, 0.5 to 2.8 parts of adhesion promoter, 0.5 to 1.2 parts of flatting agent, 0.005 to 0.1 part of pH regulator, 0.1 to 1 part of pH stabilizer, 1 to 3 parts of organic solvent and 70 to 100 parts of pure water. The invention further discloses a preparation method of the polishing solution for precise polishing of the large-size fused quartz glass. The preparation method provided by the invention can better ensure the stability of the polishing solution system containing cerium oxide and nano hexagonal boron nitride. The polishing solution provided by the invention can improve the polishing uniformity of each area of the large-size fused quartz glass in the polishing process, so that the surface type is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of precision polishing of fused silica glass, and specifically to a polishing liquid for precision polishing of large-size fused silica glass and a preparation method thereof. Background Art

[0002] High-purity synthetic fused silica material is a single-component amorphous material of silicon dioxide, with a purity higher than 99.9999%. It has unique physical properties such as excellent ultraviolet transmittance, low light absorption coefficient, high optical uniformity, and low expansion coefficient, and is known as the "king of glass" in the industry. It can be widely used in high-end manufacturing fields such as integrated circuits, optical communications, aerospace, and precision optical instruments. With the rapid development of optical technology, various application scenarios such as military reconnaissance, astronomical optics, and precision lithography have higher and higher requirements for optical components in optical systems, requiring the high-frequency error on the surface of optical components to be reduced to an extremely low level.

[0003] Currently, for the polishing of fused silica, in order to achieve higher surface shape accuracy and surface finish, the method of low polishing with an asphalt disk is often used. With the continuous progress of modern polishing technology, the existing technology has certain improvements in the polishing of small-size fused silica glass. However, for the polishing of large-size fused silica glass, there are still greater improvement requirements. For large-size fused silica glass, due to its relatively large size, during the polishing process, the distribution difference of the polishing liquid between the surface and the middle position of the workpiece is huge, resulting in poor polishing surface shape and surface finish. Especially in the low-polishing process with asphalt as the mold, after the surface shape accuracy reaches a certain level, when polishing large-size fused silica glass, the polishing removal difference between the edge position and the middle area of the polishing is huge, and even the phenomenon that the middle area of the workpiece cannot contact the polishing liquid and directly grinds against the asphalt mold will occur, resulting in poor surface shape accuracy of the polished surface and scratches on the surface. Summary of the Invention

[0004] The present invention provides a polishing liquid for precision polishing of large-size fused silica glass and a preparation method thereof for the above problems. The composition ratio of the polishing liquid for precision polishing of large-size fused silica glass is scientific, and it can solve the problems existing in the polishing of fused silica glass, especially large-size fused silica glass, such as poor polishing surface shape accuracy, poor surface finish, and poor surface roughness, improve the polishing uniformity of each area during the polishing process of large-size fused silica glass, and thus improve the surface shape.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] The polishing liquid for precision polishing of large-size fused silica glass is made of raw materials including the following parts by weight:

[0007] 0.5 - 12 parts of cerium oxide powder, 0.05 - 2.4 parts of nano - hexagonal boron nitride, 0.5 - 1.2 parts of dispersant, 0.5 - 2.8 parts of adhesion promoter, 0.5 - 1.2 parts of leveling agent, 0.1 - 1 part of pH stabilizer, 1 - 3 parts of organic solvent, 70 - 100 parts of pure water.

[0008] The cerium oxide powder is at least one of pure cerium oxide powder, cerium fluoride oxide powder, and cerium lanthanum oxide powder, and the median particle size D50 of the cerium oxide powder is 0.1 - 1.2 microns.

[0009] The particle size of the nano - hexagonal boron nitride is 0.1 - 0.5 microns.

[0010] The dispersant is at least one of acrylate copolymer, acrylate, ammonium acrylate, polyacrylic acid polymer, sodium hexametaphosphate, and sodium dodecylbenzenesulfonate;

[0011] The adhesion promoter is at least one of silane coupling agent, phosphate ester, and titanate coupling agent;

[0012] The leveling agent is at least one of polyether - modified polydimethylsiloxane, associative polyurethane, and alkyl - modified organosiloxane;

[0013] The pH stabilizer is at least one of triethanolamine, triethylamine, 4 - dimethylaminopyridine, and ethyl acetate;

[0014] The organic solvent is at least one of diethylene glycol butyl ether, diethylene glycol methyl ether, and dimethyl sulfoxide.

[0015] A polishing liquid for precision polishing of large - size fused silica glass, the composition of the polishing liquid contains cerium oxide powder and nano - hexagonal boron nitride;

[0016] Including the following steps:

[0017] S1. Add the dispersant to pure water under stirring, and continue stirring until uniform to obtain a dispersant solution;

[0018] S2. Add nano - hexagonal boron nitride and cerium oxide powder to the dispersant solution, heat to 80 - 90 °C under stirring, and then keep stirring to cool naturally to below 40 °C to obtain dispersion liquid a;

[0019] S3. Emulsify the dispersion liquid a to obtain an emulsion;

[0020] S4. Add other auxiliary components to the emulsion and mix evenly.

[0021] Preferably, the preparation method of the polishing liquid for precision polishing of large - size fused silica glass includes the following steps:

[0022] S1. Add nano hexagonal boron nitride and cerium oxide powder into the dispersant solution, stir at 300 - 800 rpm for 3 - 5 minutes to obtain the dispersant solution;

[0023] S2. Add nano hexagonal boron nitride and cerium oxide powder into the solution prepared in step S1, heat to 80 - 90 °C under stirring, stir at 1000 - 1500 rpm under natural conditions, and cool it to below 40 °C to obtain dispersion liquid a;

[0024] S3. Emulsify dispersion liquid a in an ultrasonic emulsifier for 10 - 30 minutes, then stir at 1000 - 1500 rpm until the solution temperature is below 40 °C, and then filter to remove coarse particles to obtain the emulsion;

[0025] S4. Filter the emulsion with a filtering tool of 0.8 μm - 5 μm to obtain the filtered emulsion;

[0026] S5. Add other auxiliary ingredients into the filtered emulsion, mix evenly to obtain the polishing liquid.

[0027] Further preferably, it further includes the following step S6:

[0028] S6. Adjust the pH of the polishing liquid to 8 - 10 with an alkali, and then stir for 10 - 30 minutes to obtain the polishing liquid with adjusted pH;

[0029] The alkali is sodium hydroxide, potassium hydroxide, or ammonia water.

[0030] The other auxiliary ingredients include an adhesion promoter, a leveling agent, a pH regulator, and an organic solvent;

[0031] The weight parts of each raw material in the fused silica glass precision polishing liquid are as follows:

[0032] Cerium oxide powder 0.5 - 12 parts, nano hexagonal boron nitride 0.05 - 2.4 parts, dispersant 0.5 - 1.2 parts, adhesion promoter 0.5 - 2.8 parts, leveling agent 0.5 - 1.2 parts, pH stabilizer 0.1 - 1 part, organic solvent 1 - 3 parts, pure water 70 - 100 parts.

[0033] The dispersant is at least one of acrylate copolymer, acrylate, ammonium acrylate, polyacrylic acid polymer, sodium hexametaphosphate, and sodium dodecylbenzenesulfonate;

[0034] The adhesion promoter is at least one of silane coupling agent, phosphate ester, and titanate coupling agent;

[0035] The leveling agent is at least one of polyether modified polydimethylsiloxane, associative polyurethane, and alkyl modified organosiloxane;

[0036] The pH stabilizer is at least one of triethanolamine, triethylamine, 4-dimethylaminopyridine, and ethyl acetate;

[0037] The organic solvent is at least one of diethylene glycol butyl ether, diethylene glycol methyl ether, and dimethyl sulfoxide.

[0038] The filtering tool described above includes filter cloth with a size of 0.8 μm - 5 μm, filter elements, or ceramic membranes.

[0039] The beneficial effects of the present invention are as follows:

[0040] The polishing liquid of the present invention can ensure that during the polishing process of large-size fused silica glass, the components of the polishing liquid and the abrasive grains of the polishing liquid are evenly distributed on the surfaces of the polishing mold and the polished workpiece, improving the polishing uniformity in each area during the polishing process of large-size fused silica, thereby improving the surface profile.

[0041] In the polishing liquid formula design of the present invention, a reagent for improving the leveling property is added. During the polishing process of large-size fused silica glass, the polishing liquid is kept evenly distributed on the asphalt mold, avoiding the uneven distribution of the polishing liquid caused by the liquid-phase shrinkage due to the surface tension of the liquid, which affects the surface profile of the polished surface.

[0042] In the polishing liquid formula design of the present invention, an adhesion promoter for cerium oxide powder abrasive grains is added to improve the adhesion of cerium oxide particles on the surfaces of the asphalt mold and the fused silica glass, avoiding the uneven polishing caused by the expulsion of the polishing abrasive grains from the edge area of the workpiece during the polishing process of large-size fused silica glass, and even the situation where there are no polishing abrasive grains in the middle area. The addition of the adhesion promoter improves the adhesion of the abrasive grains and the polishing uniformity, thereby improving the surface profile accuracy. At the same time, it effectively reduces the high-frequency error defects of polishing and improves the surface roughness grade, reaching the surface roughness at the angstrom level.

[0043] The polishing liquid formula of the present invention adds nano-hexagonal boron nitride particles. On the one hand, it can improve the suspension stability of the solution. On the other hand, since the hexagonal boron nitride particles are relatively soft, have a moderate hardness, and have a good adhesion effect with asphalt, during the polishing process, under the adhesion effect of hexagonal boron nitride and asphalt, the residence time of cerium oxide particles on the asphalt surface is increased, thereby improving the grinding force between cerium oxide and quartz glass and ensuring the uniformity of grinding on the edges and the center of large-size glass. At the same time, the relatively soft hardness of hexagonal boron nitride plays an anti-scratching role.

[0044] The polishing liquid formula design of the present invention is scientific. By adding an appropriate amount of solvent component, it effectively locally softens the asphalt mold during the polishing process, and effectively avoids the occurrence of scratches and uneven roughness in the case of lack or insufficient abrasive grains in the middle area during the polishing process of large-size fused silica glass.

[0045] The polishing liquid formulation of the present invention uses a pH regulator and a pH stabilizer in combination to effectively maintain the pH stability of the polishing liquid during the polishing process. During the polishing process, the pH is kept constant, improving the polishing stability.

[0046] In the polishing liquid formulation design of the present invention, under the interaction of the solvent and the adhesion promoter, not only is the adhesion of the abrasive grains improved, a transition film is formed between the abrasive grains and the surface of the fused silica, preventing the cerium oxide abrasive grains from directly adhering to the material surface and causing corrosion pits, but also the addition of a small amount of solvent softens the asphalt at the microscopic level, avoiding the appearance of scratches.

[0047] For the preparation method of the polishing liquid for precision polishing of large-size fused silica glass provided by the present invention, in view of the special properties of the nano-hexagonal boron nitride particles, the operation method of adding cerium oxide powder and nano-hexagonal boron nitride powder to the dispersant solution, then heating to 80 - 90 °C for sufficient dispersion, cooling below 40 °C and then mixing with other components is selected. Through this process, the surface of the hexagonal boron nitride particles undergoes microscopic hydrolysis, and a transition layer is formed on the particle surface, so that on the one hand, it combines with the water system, and on the other hand, it combines with the asphalt used during polishing, thus ensuring the full dispersion of cerium oxide and nano-hexagonal boron nitride and the stability of the subsequent entire polishing liquid system.

[0048] In the preparation method of the present invention, ultrasonic emulsification is adopted to obtain better dispersion under the action of the dispersant. After ultrasonic emulsification and dispersion, through filtration, the coarse particles and undispersed aggregates are filtered out, and then other reagents are added. The liquid preparation is more scientific and reasonable. The appearance of coarse particles is avoided, and at the same time, the influence of other reagents on the dispersion and filtration effects is also avoided.

[0049] The test results show that the polishing liquid for precision polishing of large-size fused silica glass prepared by the present invention can obtain a surface accuracy of 1 / 18 wavelength and a surface finish of S / D of 5 / 0 level when polishing large-size fused silica glass with a diameter of 300 mm. Description of the Drawings

[0050] Figure 1 It is a result diagram of the surface accuracy (PV) of the large-size fused silica glass after polishing by the method of Example 1. Detailed Embodiments

[0051] The present invention will be described in detail below through specific embodiments.

[0052] Example 1

[0053] The polishing liquid for precision polishing of large-size fused silica glass has the following raw materials: 90 g of cerium oxide powder, 9 g of nano-hexagonal boron nitride, 24 g of dispersant, 30 g of adhesion promoter, 15 g of leveling agent, 15 g of pH stabilizer, 3 g of solvent, and the balance is pure water.

[0054] The cerium oxide powder is pure cerium oxide powder, and the median particle size D50 is 0.8 microns.

[0055] The median particle size D50 of the nano hexagonal boron nitride powder is 0.1 microns.

[0056] The dispersant is BYK154 from BYK of Germany (the main component is acrylate copolymer);

[0057] The adhesion promoter is a silane coupling agent;

[0058] The leveling agent is polyether modified polydimethylsiloxane;

[0059] The pH stabilizer is triethanolamine;

[0060] The solvent is diethylene glycol monobutyl ether;

[0061] The balance is water, and the total preparation amount is 3 kg.

[0062] The polishing liquid for precision polishing of large-size fused silica glass, the preparation method comprises the following steps:

[0063] S1. Add the dispersant to pure water under stirring, and stir at 800 rpm for 5 minutes;

[0064] S2. Add cerium oxide powder and nano hexagonal boron nitride powder to the solution obtained in the step S1, heat to 85 °C, and then stir at 1000 rpm for 15 minutes under natural conditions to make the solution temperature lower than 40 °C, obtaining a dispersion solution;

[0065] S3. Emulsify the dispersion solution in an ultrasonic emulsifier for 10 minutes, and then stir at 1000 rpm under natural conditions to make the solution temperature lower than 40 °C;

[0066] S4. Filter the solution obtained in the step S3, and the filtration uses a 5-micron filter cloth;

[0067] S5. Add the adhesion promoter, leveling agent, pH stabilizer, and solvent to the solution obtained in the step S4, and stir evenly;

[0068] S6. Add sodium hydroxide to the solution obtained in the step S5, adjust the pH of the solution to 8, and then stir for 30 minutes.

[0069] The obtained polishing liquid is used to polish fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade laid on the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0070] After polishing, it is ultrasonically cleaned and then the surface finish is detected under a microscope, and the surface shape accuracy (PV) is detected on an interferometer. The results are asFigure 1 。

[0071] Example 2

[0072] The polishing liquid for precision polishing of large-sized fused silica glass has the following raw materials: 150 g of cerium oxide powder, 24 g of nano hexagonal boron nitride powder, 30 g of dispersant, 36 g of adhesion promoter, 24 g of leveling agent, 24 g of pH stabilizer, 36 g of solvent, and the balance is pure water.

[0073] The cerium oxide powder is pure cerium oxide powder, and the median particle size D50 is 0.8 μm;

[0074] The median particle size D50 of the nano hexagonal boron nitride powder is 0.2 μm;

[0075] The dispersant is BYK154 from BYK of Germany (the main component is acrylate copolymer);

[0076] The adhesion promoter is a silane coupling agent;

[0077] The leveling agent is polyether-modified polydimethylsiloxane;

[0078] The pH regulator in an appropriate amount is sodium hydroxide;

[0079] The pH stabilizer is triethanolamine;

[0080] The solvent is diethylene glycol monobutyl ether;

[0081] The balance is water, and the total preparation amount is 3 kg.

[0082] The preparation method of the polishing liquid for precision polishing of large-sized fused silica glass includes the following steps:

[0083] S1. Add the dispersant to pure water under stirring, and stir at 800 rpm for 5 minutes;

[0084] S2. Add cerium oxide powder and nano hexagonal boron nitride powder to the solution obtained in step S1, heat to 90 °C, and then stir at 1000 rpm for 15 minutes under natural conditions to make the solution temperature lower than 40 °C, obtaining a dispersion solution;

[0085] S3. Emulsify the dispersion solution in an ultrasonic emulsifier for 10 minutes, and then stir at 1000 rpm under natural conditions to make the solution temperature lower than 40 °C;

[0086] S4. Filter the solution obtained in step S3, and the filtration uses a 5-μm filter cloth;

[0087] S5. Add the adhesion promoter, leveling agent, pH stabilizer, and solvent to the solution obtained in step S4, and stir evenly;

[0088] S6. Add a pH regulator to the solution obtained in step S5, adjust the pH of the solution to 8, and then stir for 30 minutes.

[0089] The obtained polishing liquid is used to polish fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade laid on the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0090] Example 3

[0091] The polishing liquid for precision polishing of large-size fused silica glass has the following raw materials: 90 g of cerium oxide powder, 12 g of nano hexagonal boron nitride powder, 24 g of dispersant, 30 g of adhesion promoter, 15 g of leveling agent, 15 g of pH stabilizer, 30 g of solvent, and the balance is pure water.

[0092] The cerium oxide powder is cerium oxide powder with a fluorine-doped ratio of 3%, and the median particle size D50 is 0.8 micrometers.

[0093] The median particle size D50 of the nano hexagonal boron nitride powder is 0.3 micrometers;

[0094] The dispersant is sodium hexametaphosphate;

[0095] The adhesion promoter is titanate coupling agent;

[0096] The leveling agent is associative polyurethane;

[0097] The pH regulator in an appropriate amount is potassium hydroxide;

[0098] The pH stabilizer is triethanolamine;

[0099] The solvent is diethylene glycol monobutyl ether;

[0100] The balance is water, and the total preparation amount is 3 kg.

[0101] The preparation method of the polishing liquid for precision polishing of large-size fused silica glass includes the following steps:

[0102] S1. Add the dispersant to pure water under stirring, and stir at 800 rpm for 5 minutes;

[0103] S2. Add cerium oxide powder and nano hexagonal boron nitride powder to the solution obtained in step S1, heat to 80 °C, and then stir at 1000 rpm for 15 minutes under natural conditions to make the solution temperature lower than 40 °C, obtaining a dispersion liquid solution;

[0104] S3. Emulsify the dispersion liquid solution in an ultrasonic emulsifier for 10 minutes, and then stir at 1000 rpm under natural conditions to make the solution temperature lower than 40 °C;

[0105] S4. Filter the solution obtained in step S3 using a filter cloth with a pore size of 5 microns.

[0106] S5. Add an adhesion promoter, a leveling agent, a pH stabilizer, and a solvent to the solution obtained in step S4, and stir evenly.

[0107] S6. Add a pH regulator to the solution obtained in step S5 to adjust the pH of the solution to 9, and then stir for 30 minutes.

[0108] The obtained polishing liquid is used to polish fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade laid on the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0109] Example 4

[0110] The polishing liquid for precision polishing of large-sized fused silica glass has the following raw materials: 240 g of cerium oxide powder, 24 g of nano-hexagonal boron nitride powder, 45 g of dispersant, 45 g of adhesion promoter, 36 g of leveling agent, 24 g of pH stabilizer, 60 g of solvent, and the balance is pure water.

[0111] The cerium oxide powder is pure cerium oxide powder with a median particle size D50 of 0.8 microns.

[0112] The nano-hexagonal boron nitride powder has a median particle size D50 of 0.1 microns;

[0113] The dispersant is sodium dodecylbenzenesulfonate;

[0114] The adhesion promoter is a silane coupling agent;

[0115] The leveling agent is polyether-modified polydimethylsiloxane;

[0116] The pH regulator is sodium hydroxide in an appropriate amount;

[0117] The pH stabilizer is 4-dimethylaminopyridine;

[0118] The solvent is dimethyl sulfoxide;

[0119] The balance is water, and the total preparation amount is 3 kg.

[0120] The preparation method of the polishing liquid for precision polishing of large-sized fused silica glass includes the following steps:

[0121] S1. Add the dispersant to pure water under stirring and stir at 800 rpm for 5 minutes;

[0122] S2. Add cerium oxide powder and nano - hexagonal boron nitride powder to the solution obtained in step S1, heat it to 80 °C, then stir it at 1000 rpm under natural conditions for 15 minutes, and keep the solution temperature below 40 °C to obtain a dispersion solution;

[0123] S3. Emulsify the dispersion solution in an ultrasonic emulsifier for 10 minutes, and then stir it at 1000 rpm under natural conditions to keep the solution temperature below 40 °C;

[0124] S4. Filter the solution obtained in step S3, and use a 3 - micron filter cloth for filtration;

[0125] S5. Add an adhesion promoter, a leveling agent, a pH stabilizer, and a solvent to the solution obtained in step S4, and stir evenly;

[0126] S6. Add a pH regulator to the solution obtained in step S5, adjust the pH of the solution to 9, and then stir for 30 minutes.

[0127] The obtained polishing liquid is used to polish fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm on a ring polishing machine with a 1.6 - meter tabletop. The asphalt grade laid on the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0128] Example 5

[0129] The polishing liquid for precision polishing of large - size fused silica glass has the following raw materials: 30 g of cerium oxide powder, 3 g of nano - hexagonal boron nitride powder, 36 g of dispersant, 36 g of adhesion promoter, 36 g of leveling agent, 24 g of pH stabilizer, 45 g of solvent, and the balance is pure water.

[0130] The cerium oxide powder is pure cerium oxide powder, and the median particle size D50 is 0.3 microns.

[0131] The median particle size D50 of the nano - hexagonal boron nitride powder is 0.1 micron;

[0132] The dispersant is BYK154 from BYK of Germany (the main component is acrylate copolymer);

[0133] The adhesion promoter is a silane coupling agent;

[0134] The leveling agent is polyether - modified polydimethylsiloxane;

[0135] The pH regulator in an appropriate amount is sodium hydroxide;

[0136] The pH stabilizer is 4 - dimethylaminopyridine;

[0137] The solvent is diethylene glycol monobutyl ether;

[0138] The remainder is water, and the total preparation amount is 3 kg.

[0139] A polishing liquid for precision polishing of large-sized fused silica glass, and the preparation method includes the following steps:

[0140] S1. Add a dispersant to pure water under stirring, and stir at 800 rpm for 5 minutes;

[0141] S2. Add cerium oxide powder and nano hexagonal boron nitride powder to the solution obtained in step S1, heat to 80 °C, and then stir at 1000 rpm for 15 minutes under natural conditions to make the solution temperature lower than 40 °C, obtaining a dispersion solution;

[0142] S3. Emulsify the dispersion solution in an ultrasonic emulsifier for 10 minutes, and then stir at 1000 rpm under natural conditions to make the solution temperature lower than 40 °C;

[0143] S4. Filter the solution obtained in step S3, use a PP filter element for filtration, and the filtration accuracy is 0.8 microns;

[0144] S5. Add an adhesion promoter, a leveling agent, a pH stabilizer, and a solvent to the solution obtained in step S4, and stir evenly;

[0145] S6. Add a pH regulator to the solution obtained in step S5, adjust the pH of the solution to 8, and then stir for 30 minutes.

[0146] The obtained polishing liquid is used to polish fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade laid on the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0147] Example 6

[0148] A polishing liquid for precision polishing of large-sized fused silica glass, with raw materials: 90 g of cerium oxide powder, 18 g of nano hexagonal boron nitride powder, 24 g of dispersant, 24 g of adhesion promoter, 30 g of leveling agent, 30 g of pH stabilizer, 90 g of solvent, and the remainder is pure water.

[0149] The cerium oxide powder is cerium oxide lanthanum powder containing praseodymium, and the median particle size D50 is 1.2 microns.

[0150] The median particle size D50 of nano hexagonal boron nitride is 0.4 microns

[0151] The dispersant is BYK154 of BYK Germany (the main component is acrylate copolymer);

[0152] The adhesion promoter is a silane coupling agent;

[0153] The leveling agent is polyether-modified polydimethylsiloxane;

[0154] The pH regulator in an appropriate amount is sodium hydroxide;

[0155] The pH stabilizer is 4-dimethylaminopyridine;

[0156] The solvent is diethylene glycol monobutyl ether;

[0157] The balance is water, and the total preparation amount is 3 kg.

[0158] The polishing liquid for precision polishing of large-size fused silica glass, the preparation method includes the following steps:

[0159] S1. Add the dispersant to pure water under stirring, and stir at 800 rpm for 5 minutes;

[0160] S2. Add cerium oxide powder and nano-hexagonal boron nitride powder to the solution obtained in step S1, heat to 80 °C, and then stir at 1000 rpm for 15 minutes under natural conditions to make the solution temperature lower than 40 °C to obtain a dispersion solution;

[0161] S3. Emulsify the dispersion solution in an ultrasonic emulsifier for 10 minutes, and then stir at 1000 rpm under natural conditions to make the solution temperature lower than 40 °C;

[0162] S4. Filter the solution obtained in step S3, use a PP filter element for filtration, and the filtration accuracy is 5 microns;

[0163] S5. Add the adhesion promoter, leveling agent, pH stabilizer, and solvent to the solution obtained in step S4, and stir evenly;

[0164] S6. Add the pH regulator to the solution obtained in step S5, adjust the pH of the solution to 10, and then stir for 30 minutes.

[0165] The obtained polishing liquid is used to polish fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade of the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0166] Example 7

[0167] The polishing liquid for precision polishing of large-size fused silica glass, the raw materials are: 60 g of cerium oxide powder, 7.5 g of nano-hexagonal boron nitride powder, 15 g of dispersant, 18 g of adhesion promoter, 24 g of leveling agent, 15 g of pH stabilizer, 45 g of solvent, and the balance is pure water.

[0168] The cerium oxide powder is cerium oxide lanthanum powder containing praseodymium, and the median particle size D50 is 1.2 microns.

[0169] Nano hexagonal boron nitride powder with a median particle size D50 of 0.2 microns;

[0170] The dispersant is sodium hexametaphosphate;

[0171] The adhesion promoter is a silane coupling agent;

[0172] The leveling agent is an alkyl-modified silicone;

[0173] The pH regulator is appropriately potassium hydroxide;

[0174] The pH stabilizer is triethanolamine;

[0175] The solvent is diethylene glycol methyl ether;

[0176] The balance is water, and the total preparation amount is 3 kg.

[0177] A polishing liquid for precision polishing of large-size fused silica glass, and the preparation method includes the following steps:

[0178] S1. Add the dispersant to pure water under stirring, and stir at 800 rpm for 5 minutes;

[0179] S2. Add cerium oxide powder and nano hexagonal boron nitride powder to the solution obtained in step S1, heat to 80 °C, and then stir at 1000 rpm for 15 minutes under natural conditions to make the solution temperature lower than 40 °C, obtaining a dispersion solution;

[0180] S3. Emulsify the dispersion solution in an ultrasonic emulsifier for 10 minutes, and then stir at 1000 rpm under natural conditions to make the solution temperature lower than 40 °C;

[0181] S4. Filter the solution obtained in step S3, and the filtration uses a 5-micron filter cloth;

[0182] S5. Add the adhesion promoter, leveling agent, pH stabilizer, and solvent to the solution obtained in step S4, and stir evenly;

[0183] S6. Add the pH regulator to the solution obtained in step S5, adjust the pH of the solution to 8, and then stir for 30 minutes.

[0184] The obtained polishing liquid is used to polish fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade paved on the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0185] Example 8

[0186] Polishing liquid for precision polishing of large-sized fused silica glass, with raw materials including: 300 g of cerium oxide powder, 24 g of nano hexagonal boron nitride powder, 30 g of dispersant, 30 g of adhesion promoter, 30 g of leveling agent, 30 g of pH stabilizer, 90 g of solvent, and the balance being pure water.

[0187] The cerium oxide powder is cerium lanthanum powder containing praseodymium, with a median particle size D50 of 1 micron.

[0188] The median particle size D50 of nano hexagonal boron nitride is 0.2 micron.

[0189] The dispersant is BYK154 from BYK of Germany (the main component is acrylate copolymer) and sodium hexametaphosphate.

[0190] The adhesion promoter is a silane coupling agent.

[0191] The leveling agent is alkyl-modified organosiloxane and associative polyurethane.

[0192] The pH regulator is appropriately potassium hydroxide and ammonia water.

[0193] The pH stabilizer is triethanolamine.

[0194] The solvent is dimethyl sulfoxide.

[0195] The balance is water, and the total preparation amount is 3 kg.

[0196] The preparation method of the polishing liquid for precision polishing of large-sized fused silica glass includes the following steps:

[0197] S1. Add the dispersant to pure water under stirring, and stir at 800 rpm for 5 minutes.

[0198] S2. Add the cerium oxide powder and nano hexagonal boron nitride powder to the solution obtained in step S1, heat to 85 °C, and then stir at 1000 rpm for 15 minutes under natural conditions to make the solution temperature lower than 40 °C, obtaining a dispersion solution.

[0199] S3. Emulsify the dispersion solution in an ultrasonic emulsifier for 10 minutes, and then stir at 1000 rpm under natural conditions to make the solution temperature lower than 40 °C.

[0200] S4. Filter the solution obtained in step S3, using a PP filter element with a filtration accuracy of 3 microns.

[0201] S5. Add the adhesion promoter, leveling agent, pH stabilizer, and solvent to the solution obtained in step S4, and stir evenly.

[0202] S6. Add the pH regulator to the solution obtained in step S5, adjust the solution pH to 10, and then stir for 30 minutes.

[0203] The obtained polishing liquid is used to polish fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade laid on the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0204] Commercially available cerium oxide polishing liquid or polishing powder is used to polish large-size fused silica glass under the same conditions, and the following Comparative Examples 1 - 10 are carried out.

[0205] Example 9

[0206] A polishing liquid for precision polishing of large-size fused silica glass is made from the following raw materials:

[0207] 5 g of cerium oxide powder, 0.5 g of nano hexagonal boron nitride, 5 g of dispersant, 5 g of adhesion promoter, 5 g of leveling agent, 1 g of pH stabilizer, 10 g of organic solvent, and 700 g of pure water.

[0208] The cerium oxide powder is a 1:1 weight ratio mixture of pure cerium oxide powder and cerium oxyfluoride powder, and the median particle size D50 of the cerium oxide powder is 0.1 micrometer.

[0209] The particle size of the nano hexagonal boron nitride is 0.1 micrometer.

[0210] The dispersant is a 1:1:1 weight ratio mixture of acrylate copolymer, acrylate, and ammonium acrylate;

[0211] The adhesion promoter is at least one of silane coupling agent, phosphate ester, and titanate coupling agent;

[0212] The leveling agent is a 1:1 weight ratio mixture of polyether-modified polydimethylsiloxane and associative polyurethane;

[0213] The pH stabilizer is a 1:1 weight ratio mixture of triethanolamine and triethylamine;

[0214] The organic solvent is a 1:1 weight ratio mixture of diethylene glycol butyl ether and diethylene glycol methyl ether;

[0215] A preparation method of a polishing liquid for precision polishing of large-size fused silica glass includes the following steps:

[0216] S1. Add nano hexagonal boron nitride and cerium oxide powder into the dispersant solution, and stir at 300 rpm for 3 minutes to obtain a dispersant solution;

[0217] S2. Add nano hexagonal boron nitride and cerium oxide powder to the solution prepared in step S1, heat it to 80 °C with stirring, stir it at 1000 rpm under natural conditions, and cool it to below 40 °C to obtain dispersion liquid a;

[0218] S3. Emulsify dispersion liquid a in an ultrasonic emulsifier for 10 minutes, then stir it at 1000 rpm until the solution temperature is below 40 °C, and then filter to remove coarse particles to obtain an emulsion;

[0219] S4. Filter the emulsion with a 0.8-micron filter cloth, filter element, or ceramic membrane to obtain a filtered emulsion;

[0220] S5. Add other auxiliary components to the filtered emulsion and mix evenly to obtain a polishing liquid.

[0221] S6. Adjust the pH of the polishing liquid to 8 with sodium hydroxide, potassium hydroxide, or ammonia water, and then stir for 10 minutes to obtain a polishing liquid with adjusted pH.

[0222] Example 10

[0223] The polishing liquid for precision polishing of large-size fused silica glass is made from the following raw materials:

[0224] 120 g of cerium oxide powder, 24 g of nano hexagonal boron nitride, 12 g of dispersant, 28 g of adhesion promoter, 12 g of leveling agent, 10 g of pH stabilizer, 30 g of organic solvent, and 1000 g of pure water.

[0225] The cerium oxide powder is a mixture of pure cerium oxide powder, cerium oxyfluoride powder, and cerium lanthanum oxide powder with a weight ratio of 1:1:1, and the median particle size D50 of the cerium oxide powder is 1.2 microns.

[0226] The particle size of the nano hexagonal boron nitride is 0.5 microns.

[0227] The dispersant is a mixture of polyacrylic acid polymer, sodium hexametaphosphate, and sodium dodecylbenzenesulfonate with a weight ratio of 1:1:1;

[0228] The adhesion promoter is a mixture of silane coupling agent, phosphate ester, and titanate coupling agent with a weight ratio of 1:1:1;

[0229] The leveling agent is a mixture of polyether-modified polydimethylsiloxane, associative polyurethane, and alkyl-modified organosiloxane with a weight ratio of 1:1:1;

[0230] The pH stabilizer is a mixture of 4-dimethylaminopyridine and ethyl acetate with a weight ratio of 1:1;

[0231] The organic solvent is a mixture of diethylene glycol methyl ether and dimethyl sulfoxide with a weight ratio of 1:1.

[0232] Preparation method of polishing liquid for precision polishing of large-size fused silica glass, comprising the following steps:

[0233] S1. Add nano hexagonal boron nitride and cerium oxide powder into the dispersant solution, stir at 800 rpm for 5 minutes to obtain the dispersant solution;

[0234] S2. Add nano hexagonal boron nitride and cerium oxide powder into the solution obtained in step S1, heat to 90 °C under stirring, stir at 1500 rpm under natural conditions, and cool it to below 40 °C to obtain dispersion liquid a;

[0235] S3. Emulsify dispersion liquid a in an ultrasonic emulsifier for 30 minutes, then stir at 1500 rpm until the solution temperature is below 40 °C, and then filter to remove coarse particles to obtain the emulsion;

[0236] S4. Filter the emulsion with a 5-micron filter cloth, filter element, or ceramic membrane to obtain the filtered emulsion;

[0237] S5. Add other auxiliary components to the filtered emulsion, mix evenly to obtain the polishing liquid.

[0238] S6. Adjust the pH of the polishing liquid to 10 with sodium hydroxide, potassium hydroxide, or ammonia water, and then stir for 30 minutes to obtain the polishing liquid with adjusted pH.

[0239] Example 11

[0240] Polishing liquid for precision polishing of large-size fused silica glass, made from the following raw materials:

[0241] 80 g of cerium oxide powder, 10 g of nano hexagonal boron nitride, 9 g of dispersant, 12 g of adhesion promoter, 8 g of leveling agent, 5 g of pH stabilizer, 20 g of organic solvent, 800 g of pure water.

[0242] The cerium oxide powder is a 1:1 weight ratio mixture of cerium oxyfluoride powder and cerium lanthanum oxide powder, and the median particle size D50 of the cerium oxide powder is 0.6 microns.

[0243] The particle size of the nano hexagonal boron nitride is 0.1 micron - 0.5 microns.

[0244] The dispersant is a 1:1 weight ratio mixture of ammonium acrylate salt and polyacrylic acid polymer;

[0245] The adhesion promoter is a 1:1 weight ratio mixture of silane coupling agent and titanate coupling agent;

[0246] The leveling agent is a 1:1 weight ratio mixture of polyether-modified polydimethylsiloxane and alkyl modification;

[0247] The pH stabilizer is a 1:1 weight ratio mixture of triethanolamine and ethyl acetate;

[0248] The organic solvent is a 1:1 weight ratio mixture of diethylene glycol butyl ether and dimethyl sulfoxide.

[0249] A method for preparing a polishing liquid for precision polishing of large-size fused silica glass, comprising the following steps:

[0250] S1. Add nano hexagonal boron nitride and cerium oxide powder to the dispersant solution, and stir at 500 rpm for 4 minutes to obtain a dispersant solution;

[0251] S2. Add nano hexagonal boron nitride and cerium oxide powder to the solution prepared in step S1, heat to 86 °C with stirring, and stir at 1200 rpm under natural conditions until it cools below 40 °C to obtain dispersion liquid a;

[0252] S3. Emulsify dispersion liquid a in an ultrasonic emulsifier for 20 minutes, then stir at 1200 rpm until the solution temperature is below 40 °C, and then filter to remove coarse particles to obtain an emulsion;

[0253] S4. Filter the emulsion with a 2-micron filter cloth, filter element, or ceramic membrane to obtain a filtered emulsion;

[0254] S5. Add other auxiliary components to the filtered emulsion and mix evenly to obtain a polishing liquid.

[0255] S6. Adjust the pH of the polishing liquid to 9 with sodium hydroxide, potassium hydroxide, or ammonia water, and then stir for 20 minutes to obtain a polishing liquid with adjusted pH.

[0256] Comparative Example 1

[0257] A precision polishing liquid for fused silica glass, containing the following components by weight fraction: 5% cerium oxide powder, 1% dispersant, 1.2% adhesion promoter, 0.8% leveling agent, appropriate amount of pH regulator, 0.8% pH stabilizer, 1.2% solvent, and the balance is pure water.

[0258] The cerium oxide powder is pure cerium oxide powder, and the median particle size D50 is 0.8 microns;

[0259] The dispersant is BYK154 from BYK of Germany (the main component is acrylate copolymer);

[0260] The adhesion promoter is a silane coupling agent;

[0261] The leveling agent is polyether-modified polydimethylsiloxane;

[0262] The appropriate amount of pH regulator is sodium hydroxide;

[0263] The PH stabilizer is triethanolamine;

[0264] The solvent is diethylene glycol monobutyl ether;

[0265] The balance is water, and the total preparation amount is 3 kg.

[0266] The fused silica glass precision polishing liquid, the preparation method comprises the following steps:

[0267] S1. Add the dispersant to pure water under stirring, and stir at 800 rpm for 5 minutes;

[0268] S2. Add cerium oxide powder to the solution obtained in step S1, heat to 90 °C, stir at 1000 rpm for 15 minutes, and wait for the solution temperature to be lower than 40 °C;

[0269] S3. Emulsify the solution obtained in step S2 in an ultrasonic emulsifier for 10 minutes, then stir at 1000 rpm, and wait for the solution temperature to be lower than 40 °C;

[0270] S4. Filter the solution obtained in step S3, and the filtration uses a 5-micron filter cloth;

[0271] S5. Add an adhesion promoter, a leveling agent, a PH stabilizer, and a solvent to the solution obtained in step S4, and stir evenly;

[0272] S6. Add a PH regulator to the solution obtained in step S5, adjust the PH of the solution to 8, and then stir for 30 minutes.

[0273] The obtained polishing liquid is used to polish a fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade laid on the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0274] Comparative Example 2

[0275] The fused silica glass precision polishing liquid contains the following components by weight fraction: 5% cerium oxide powder, 1% dispersant, 0.8% leveling agent, appropriate amount of PH regulator, 0.8% PH stabilizer, 1.2% solvent, and the balance is pure water.

[0276] The cerium oxide powder is pure cerium oxide powder, and the median particle size D50 is 0.8 microns;

[0277] The dispersant is BYK154 of BYK Germany (the main component is acrylate copolymer);

[0278] The leveling agent is polyether-modified polydimethylsiloxane;

[0279] The appropriate amount of the pH regulator is sodium hydroxide;

[0280] The pH stabilizer is triethanolamine;

[0281] The solvent is diethylene glycol monobutyl ether;

[0282] The balance is water, and the total preparation amount is 3 kg.

[0283] The fused silica glass precision polishing liquid, the preparation method comprises the following steps:

[0284] S1. Add the dispersant to pure water under stirring, and stir at 800 rpm for 5 minutes;

[0285] S2. Add cerium oxide powder to the solution obtained in the step S1, heat to 90 °C, stir at 1000 rpm for 15 minutes, and wait until the solution temperature is lower than 40 °C;

[0286] S3. Emulsify the solution obtained in the step S2 in an ultrasonic emulsifier for 10 minutes, and then stir at 1000 rpm, and wait until the solution temperature is lower than 40 °C;

[0287] S4. Filter the solution obtained in the step S3, and the filtration is carried out with a 5-micron filter cloth;

[0288] S5. Add a leveling agent, a pH stabilizer, and a solvent to the solution obtained in the step S4, and stir evenly;

[0289] S6. Add a pH regulator to the solution obtained in the step S5, adjust the pH of the solution to 8, and then stir for 30 minutes.

[0290] The obtained polishing liquid is used to polish the fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade laid on the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0291] Comparative Example 3

[0292] The fused silica glass precision polishing liquid contains the following components by weight fraction: 5% of cerium oxide powder, 1% of dispersant, 0.8% of leveling agent, an appropriate amount of pH regulator, 0.8% of pH stabilizer, and the balance is pure water.

[0293] The cerium oxide powder is pure cerium oxide powder, and the median particle size D50 is 0.8 microns;

[0294] The dispersant is BYK154 of BYK of Germany (the main component is acrylate copolymer);

[0295] The leveling agent is polyether-modified polydimethylsiloxane;

[0296] The appropriate amount of pH regulator is sodium hydroxide;

[0297] The pH stabilizer is triethanolamine;

[0298] The balance is water, and the total preparation amount is 3 kg.

[0299] Fused silica glass precision polishing liquid, and the preparation method includes the following steps:

[0300] S1. Add the dispersant to pure water under stirring, and stir at 800 rpm for 5 minutes;

[0301] S2. Add cerium oxide powder to the solution obtained in step S1, heat to 90 °C, stir at 1000 rpm for 15 minutes, and wait until the solution temperature is lower than 40 °C;

[0302] S3. Emulsify the solution obtained in step S2 in an ultrasonic emulsifier for 10 minutes, and then stir at 1000 rpm until the solution temperature is lower than 40 °C;

[0303] S4. Filter the solution obtained in step S3, and the filtration uses a 5-micron filter cloth;

[0304] S5. Add a leveling agent and a pH stabilizer to the solution obtained in step S4, and stir evenly;

[0305] S6. Add a pH regulator to the solution obtained in step S5, adjust the pH of the solution to 8, and then stir for 30 minutes.

[0306] The obtained polishing liquid is used to polish fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade laid on the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0307] Comparative Example 4

[0308] Qingdao Fulu Taike Surface Materials Technology Co., Ltd. provides 0.5-micron specification cerium oxide formula powder, the median particle size D50 of cerium oxide is 0.5 microns, and the cerium oxide content is 1%.

[0309] Polish fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade laid on the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0310] Comparative Example 5

[0311] The 355 model cerium oxide formula powder provided by Dongguan Tiansheng New Materials Co., Ltd., the median particle size D50 of cerium oxide is 0.8 microns, and the cerium oxide content is 3%.

[0312] The fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm is polished on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade laid on the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0313] Comparative Example 6

[0314] The cerium oxide formulated powder of model 355 provided by Dongguan Tiansheng New Materials Co., Ltd. has a median particle size D50 of cerium oxide of 0.8 microns and a cerium oxide content of 5%.

[0315] The fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm is polished on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade laid on the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0316] Comparative Example 7

[0317] The cerium oxide formulated powder of model 355 provided by Dongguan Tiansheng New Materials Co., Ltd. has a median particle size D50 of cerium oxide of 0.8 microns and a cerium oxide content of 8%.

[0318] The fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm is polished on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade laid on the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0319] Comparative Example 8

[0320] The commercially available cerium oxide formulated polishing powder, with the brand of Rhodia and the model specification of CEROX 2663, has a median particle size D50 of cerium oxide of 1.2 microns, and is directly mixed with pure water to prepare a polishing liquid, with a cerium oxide content of 3%.

[0321] The fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm is polished on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade laid on the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0322] Comparative Example 9

[0323] The commercially available cerium oxide formulated polishing powder, with the brand of Rhodia and the model specification of CEROX 2663, has a median particle size D50 of cerium oxide of 1.2 microns, and is directly mixed with pure water to prepare a polishing liquid, with a cerium oxide content of 2%.

[0324] The fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm is polished on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade laid on the ring polishing machine is CP64, the polishing speed is 1 rpm, and the polishing time is 4 hours.

[0325] Comparative Example 10

[0326] Commercially available cerium oxide formulated powder, model LCE-99, with a median particle size D50 of cerium oxide of 1.0 μm, was directly mixed with pure water to prepare a polishing liquid, and the cerium oxide content was 10%.

[0327] Fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm was polished on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade laid on the ring polishing machine was CP64, the polishing speed was 1 rpm, and the polishing time was 4 hours.

[0328] II. Experimental Results

[0329] The parameters of the above-mentioned examples and comparative examples are as shown in Table 1 below:

[0330]

[0331]

[0332] The above-mentioned examples and comparative examples were polished on large-size fused silica glass under the same conditions (fused silica glass (JGS1) with a diameter of 300 mm and a thickness of 50 mm was polished on a ring polishing machine with a 1.6-meter tabletop. The asphalt grade laid on the ring polishing machine was CP64, the polishing speed was 1 rpm, and the polishing time was 4 hours). After being cleaned by an ultrasonic cleaning machine, the surface finish of the workpiece surface was detected under a microscope, and the surface shape accuracy of the workpiece was tested on a digital interferometer. The experimental results are as shown in Table 2 below:

[0333] Number Surface form accuracy (PV / nm) Surface finish (S / D) Example 1 35.473 10 / 5 Example 2 37.433 10 / 5 Example 3 34.253 10 / 5 Example 4 38.345 10 / 5 Example 5 45.564 5 / 0 Example 6 32.200 20 / 10 Example 7 30.267 10 / 5 Example 8 50.624 10 / 5 Comparative Example 1 48.624 60 / 40 Comparative Example 2 130.664 60 / 40 Comparative Example 3 180.478 100 / 80 Comparative Example 4 129.432 40 / 20 Comparative Example 5 105.675 40 / 20 Comparative Example 6 189.452 60 / 40 Comparative Example 7 213.560 60 / 40 Comparative Example 8 100.244 60 / 40 Comparative Example 9 80.655 20 / 10 Comparative Example 10 221.655 80 / 60

[0334] It can be seen from the above experimental results that the surface shape accuracy and surface finish of the examples of the present invention are much better than those of the comparative examples; among them, the surface finish of Example 6 is 20 / 10. Although it is equivalent to that of Comparative Example 6, the surface shape accuracy is much better than that of the comparative example. It can be understood that the pH of Example 6 is too high and the amount of solvent added is too large. In the subsequent formula, reducing the usage amounts of these two reagents can effectively avoid this. In Comparative Example 1, hexagonal boron nitride was not added, and the surface shape accuracy was relatively good, but the surface finish was relatively poor; Comparative Example 2 was based on Comparative Example 1 and the adhesion promoter was removed, resulting in relatively poor surface shape and surface finish; Comparative Example 3 was based on Comparative Example 2 and the solvent was removed, and the surface shape accuracy and surface finish of the polishing were very poor, especially the surface finish was only 100 / 80, and the effect was extremely poor. Through the above experimental results, the examples of the present invention can significantly improve the surface shape accuracy and surface finish of precision polishing of large-size fused silica glass.

[0335] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in the disclosure of the present invention can be executed in parallel, sequentially, or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and no limitation is imposed herein.

[0336] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A polishing liquid for precision polishing of large-size fused quartz glass, characterized in that: Made from the following raw materials in parts by weight: 0.5-12 parts of cerium oxide powder, 0.05-2.4 parts of nano hexagonal boron nitride, 0.5-1.2 parts of dispersant, 0.5-2.8 parts of adhesion promoter, 0.5-1.2 parts of leveling agent, 0.1-1 parts of pH stabilizer, 1-3 parts of organic solvent, and 70-100 parts of pure water.

2. The polishing liquid for precision polishing of large-size fused quartz glass according to claim 1, characterized in that: The cerium oxide powder is at least one of pure cerium oxide powder, cerium oxide powder with fluoride, and cerium lanthanum oxide powder. The central particle size D50 of the cerium oxide powder is 0.1 micrometers to 1.2 micrometers.

3. The polishing liquid for precision polishing of large-size fused quartz glass according to claim 1, characterized in that: The particle size of the nano hexagonal boron nitride is 0.1 micron to 0.5 micron.

4. The polishing liquid for precision polishing of large-size fused quartz glass according to claim 1, characterized in that: The dispersant is at least one of acrylate copolymer, acrylate, ammonium acrylate, polyacrylic acid polymer, sodium hexametaphosphate, and sodium dodecylbenzene sulfonate; The adhesion promoter is at least one of a silane coupling agent, a phosphate ester, and a titanate coupling agent; The leveling agent is at least one of polyether-modified polydimethylsiloxane, associative polyurethane, and alkyl-modified organic siloxane; The pH stabilizer is at least one of triethanolamine, triethylamine, 4-dimethylaminopyridine and ethyl acetate; The organic solvent is at least one of diethylene glycol butyl ether, diethylene glycol methyl ether and dimethyl sulfoxide.

5. A method for preparing a polishing liquid for precision polishing of large-size fused quartz glass, characterized in that: The polishing liquid contains cerium oxide powder and nano hexagonal boron nitride; The following steps are involved: S1. Add the dispersant into pure water under stirring, and continue stirring until uniform to obtain a dispersant solution; S2, adding nano hexagonal boron nitride and cerium oxide powder to the dispersant solution, heating to 80-90° C. while stirring, and then cooling naturally to below 40° C. while maintaining stirring, to obtain dispersion a; S3, emulsifying the dispersion a to obtain an emulsion; S4. Add other auxiliary ingredients to the emulsion and mix well.

6. The method for preparing a polishing liquid for precision polishing of large-size fused quartz glass according to claim 5, characterized in that: The following steps are involved: S1. Add nano hexagonal boron nitride and cerium oxide powder to the dispersant solution, and stir at 300-800 rpm for 3-5 minutes to obtain a dispersant solution; S2, adding nano hexagonal boron nitride and cerium oxide powder to the solution prepared in step S1, heating to 80-90° C. with stirring, stirring at 1000-1500 rpm under natural conditions, and cooling it to below 40° C. to obtain dispersion a; S3, emulsifying the dispersion a in an ultrasonic emulsifier for 10-30 minutes, then stirring at 1000-1500 rpm until the solution temperature is lower than 40° C., then filtering to remove coarse particles to obtain an emulsion; S4, filtering the emulsion using a 0.8 micron-5 micron filter to obtain a filtered emulsion; S5. Add other auxiliary ingredients to the filtered emulsion, mix well, and obtain polishing liquid.

7. The method for preparing a polishing liquid for precision polishing of large-size fused quartz glass according to claim 5 or 6, characterized in that: The other auxiliary materials include adhesion promoter, leveling agent, pH regulator and organic solvent; The weight proportions of the raw materials in the fused quartz glass precision polishing liquid are as follows: 0.5-12 parts of cerium oxide powder, 0.05-2.4 parts of nano hexagonal boron nitride, 0.5-1.2 parts of dispersant, 0.5-2.8 parts of adhesion promoter, 0.5-1.2 parts of leveling agent, 0.1-1 parts of pH stabilizer, 1-3 parts of organic solvent, and 70-100 parts of pure water.

8. The method for preparing a polishing liquid for precision polishing of large-size fused quartz glass according to claim 7, characterized in that: The dispersant is at least one of acrylate copolymer, acrylate, ammonium acrylate, polyacrylic acid polymer, sodium hexametaphosphate, and sodium dodecylbenzene sulfonate; The adhesion promoter is at least one of a silane coupling agent, a phosphate ester, and a titanate coupling agent; The leveling agent is at least one of polyether-modified polydimethylsiloxane, associative polyurethane, and alkyl-modified organic siloxane; The pH stabilizer is at least one of triethanolamine, triethylamine, 4-dimethylaminopyridine and ethyl acetate; The organic solvent is at least one of diethylene glycol butyl ether, diethylene glycol methyl ether and dimethyl sulfoxide.

9. The method for preparing a polishing liquid for precision polishing of large-size fused quartz glass according to claim 6, characterized in that: The filtering tool includes a filter cloth, a filter element, or a ceramic membrane with a filter size of 0.8 micron to 5 micron.

10. The method for preparing a polishing liquid for precision polishing of large-size fused quartz glass according to claim 6, characterized in that: The following step S6 is also included: S6, adjusting the pH of the polishing liquid to 8-10 with an alkali solution, and then stirring for 10-30 minutes to obtain a polishing liquid with adjusted pH; The alkali is sodium hydroxide, potassium hydroxide, or ammonia water.

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