Grinding and polishing method for fused quartz

Abstract

The invention discloses a fused quartz grinding and polishing method which comprises the following steps: S1, milling and grinding: removing defects on the surface of a fused quartz element through a milling and grinding machine until the fused quartz element is close to the required thickness size; s2, grinding is conducted, specifically, the milled and ground element is put into a ring mill, surface flaws are further removed through grinding, and meanwhile a damaged layer is reduced; s3, high-speed ring polishing is conducted, specifically, the ground element is put into a high-speed ring polishing machine, a mirror surface is rapidly polished, and the face type PV precision is made to be below one wavelength, namely 632.8 nm; s4, precise ring polishing: putting the element subjected to high-speed polishing into a precise ring polishing machine, and carrying out fine trimming on the surface type of the element, so that the PV of the surface type reaches one tenth of the wavelength, namely 63.28 nm or below; and S5, the polished element is cleaned up, and then the polishing element is obtained. According to the method, the grinding and polishing speed of the fused quartz can be increased, surface damage is reduced, and the high-precision surface type is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of fused quartz cold processing technology, in particular to a grinding and polishing method for fused quartz. Background Art

[0002] Fused quartz glass is widely used in the manufacture of key optical components in the fields of national defense, aerospace, laser nuclear fusion, etc. due to its excellent mechanical properties, optical properties and chemical stability. For example, due to its low thermal expansion coefficient and excellent mechanical properties, fused quartz is used as spacecraft windows, missile infrared windows and solar shields; on the other hand, based on its good ultraviolet light transmission and resistance to strong laser damage, it is used to make focusing lenses, gratings, etc. As an optical element, fused quartz has very high requirements for its processing quality and efficiency. At present, the domestic process mainly adopts the "grinding-forming-grinding-polishing" process. This existing technology process has many problems, such as low grinding and polishing efficiency, surface damage, poor surface shape accuracy, etc.

[0003] Therefore, it is necessary to develop a fused quartz grinding and polishing method with higher grinding efficiency and better surface accuracy. Summary of the invention

[0004] The present invention provides a fused quartz grinding and polishing method for the above-mentioned problems. The fused quartz grinding and polishing method can improve the grinding and polishing rate of the fused quartz, reduce surface damage, and has the characteristics of high-precision surface shape.

[0005] To achieve the above object, the technical solution of the present invention is as follows: The grinding and polishing method of fused quartz comprises the following steps: S1, milling, using a milling machine to remove surface defects of the fused quartz component to approach the required thickness size; S2, grinding, after cleaning the milled components, put them into the ring grinder for further grinding to remove surface defects and reduce the damage layer; S3, high-speed ring polishing, after cleaning the ground components, put them into the high-speed ring polishing machine, and quickly polish them into a mirror surface, so that the accuracy of the double-sided PV is below 1 wavelength, i.e. 632.8nm; S4, precision ring polishing, after cleaning the components that have been polished by high speed, put them into the precision ring polishing machine to fine-tune the surface type PV of the components, so that the double-sided surface type PV accuracy is less than one tenth of the wavelength, that is, 63.28nm; S5. Clean the polished components.

[0006] In the step S1, the rotation speed of the grinding wheel of the milling machine is between 1000 r / min and 1400 r / min.

[0007] In the step S2, the abrasive used in the ring mill is a mixture of silicon carbide and water in a weight ratio of 1:15-25, wherein the particle size of the silicon carbide is 14 μm to 40 μm, and the speed of the ring mill is 10 r / min to 30 r / min.

[0008] In step S3, the high-speed ring polishing machine uses polyurethane as the polishing pad, and the abrasive used is a mixture of cerium oxide and water in a weight ratio of 1:20-60, wherein the particle size of cerium oxide is 2.0 μm to 3.0 μm, and the speed of the high-speed ring polishing machine is 12 r / min to 30 r / min.

[0009] In step S4, the precision ring polishing machine uses optical polishing asphalt as the polishing pad, uses cerium oxide with a particle size of 0.5 μm to 1.5 μm as the abrasive to prepare a cerium oxide polishing liquid, and the rotation speed is 0.5 r / min to 1.5 r / min.

[0010] The cerium oxide polishing liquid is composed of the following components in parts by weight: 1 to 10 parts of cerium oxide, 0.001 to 1 part of dispersant, 0.0001 to 1 part of pH regulator, and 80 to 98 parts of deionized water.

[0011] The particle size of the cerium oxide is 0.8-1.2 μm.

[0012] The dispersant is at least one of sodium pyrophosphate, sodium tripolyphosphate, sodium polymethacrylate, sodium polyacrylate, polyvinyl alcohol, polyethylene glycol, and polyvinyl pyrrolidone.

[0013] The pH regulator is at least one of sodium hydroxide, potassium hydroxide, ammonia water, triethanolamine, sodium carbonate and sodium bicarbonate.

[0014] The beneficial effects of the present invention are: The grinding and polishing method of the present invention uses a combination process of milling, grinding, high-speed ring polishing and precision ring polishing, and a reasonable processing combination sequence from coarse to fine, and each processing link selects the most suitable processing equipment, that is, the processing method, so that the surface defects of fused quartz can be quickly removed, and the purpose of thinning and polishing can be quickly achieved, thereby improving the polishing efficiency.

[0015] Moreover, the present invention can remove the damaged layer step by step through milling, grinding, high-speed ring polishing and precision ring polishing in sequence, and finally achieves high precision of the surface profile PV of the processed component, and can effectively reduce the occurrence of surface damage of the processed component, improve the qualified rate of finished products, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the result of surface inspection of the fused quartz component after polishing; Figure 2 This is a picture of the fused quartz component after polishing. DETAILED DESCRIPTION

[0017] The present invention is described in detail below through specific embodiments. Example 1

[0018] S1 A fused quartz disc with a diameter of 180 mm and a thickness of 42 mm was milled at a speed of 1000 r / min using a milling machine, and 0.8 mm was removed from one side by milling.

[0019] S2 The milled disc is cleaned and then put into a grinder for grinding. Silicon carbide with a particle size of 28 μm is used as an abrasive and mixed with water at a ratio of 1:15. The grinding speed is 15 r / min and the single-side grinding size is 0.15 mm.

[0020] S3: The ground wafer is cleaned and then put into a high-polishing ring polishing machine for polishing. Cerium oxide with a particle size of 3.0 μm is used as an abrasive and mixed with water at a ratio of 1:40. The polishing is performed at a speed of 25 r / min until the double-sided PV accuracy is below 1 wavelength, i.e. 632.8 nm. S4: Clean the high-polished wafers and put them into the precision ring polishing machine for further polishing. Use 1.2μm cerium oxide polishing liquid and polish at a speed of 0.5r / min until the double-sided PV precision is less than one-tenth of the wavelength, i.e. 63.28nm. S5 cleans the polished wafer and then uses a digital interferometer to detect the surface shape. The PV accuracy is 46.937nm.

[0021] In this embodiment, the cerium oxide polishing liquid used in S4 is prepared by stirring 5g of sodium polyacrylate in 4800g of deionized water, adding 2g of sodium hydroxide after the sodium polyacrylate is completely dissolved, and finally adding 125g of cerium oxide with a particle size of 1.2μm, stirring thoroughly and ultrasonicating for 30min. Example 2

[0022] S1 A fused quartz disc with a diameter of 190 mm and a thickness of 38 mm was milled at a speed of 1200 r / min using a milling machine, and 1.4 mm was removed from one side by milling.

[0023] S2 The milled disc is cleaned and then put into a grinder for grinding. 14μm silicon carbide is used as an abrasive and mixed with water at a ratio of 1:20. The grinding speed is 12r / min and the single-side grinding size is 0.1mm.

[0024] S3: The ground wafer is cleaned and then put into a high-polishing ring polishing machine for polishing. Cerium oxide with a particle size of 2.0 μm is used as an abrasive and mixed with water at a ratio of 1:50. The wafer is polished at a speed of 12 r / min until the double-sided PV accuracy is below 1 wavelength, i.e. 632.8 nm. S4: Clean the high-polished wafer, put it into the precision ring polishing machine for further polishing, use 0.8μm cerium oxide polishing liquid, and perform fine polishing at a speed of 1.2r / min until the double-sided PV accuracy is less than one-tenth of the wavelength, i.e. 63.28nm; S5 cleans the polished wafer and then uses a digital interferometer to detect the surface shape. The PV accuracy is 48.186nm.

[0025] In this embodiment, the cerium oxide polishing liquid used in S4 is prepared by stirring 6g of polyvinyl pyrrolidone in 4800g of deionized water, adding 2g of potassium hydroxide after the sodium polyacrylate is completely dissolved, and finally adding 200g of cerium oxide with a particle size of 0.8μm, stirring thoroughly and ultrasonicating for 30min. Example 3

[0026] S1 A fused quartz disc with a diameter of 200 mm and a thickness of 55 mm was milled at a speed of 1300 r / min using a milling machine, and 2.3 mm was removed from one side by milling.

[0027] S2 The milled disc is cleaned and then put into a grinder for grinding. Silicon carbide with a particle size of 32 μm is used as an abrasive and mixed with water at a ratio of 1:20. The grinding speed is 15 r / min and the single-side grinding size is 0.2 mm.

[0028] S3: The ground wafer is cleaned and then put into a high-polishing ring polishing machine for polishing. Cerium oxide with a particle size of 3.0 μm is used as an abrasive and mixed with water at a ratio of 1:50. The wafer is polished at a speed of 20 r / min until the double-sided PV accuracy is below 1 wavelength, i.e. 632.8 nm. S4: Clean the high-polished wafer, put it into the precision ring polishing machine for further polishing, use 1.5μm cerium oxide polishing liquid, and perform fine polishing at a speed of 1.0r / min until the double-sided PV precision is less than one-tenth of the wavelength, i.e. 63.28nm; S5 cleans the polished wafer and detects the surface shape through a digital interferometer after cleaning. The PV accuracy is 61.532nm In this embodiment, the cerium oxide polishing liquid used in S4 is prepared by stirring 8g of sodium pyrophosphate in 4800g of deionized water, adding 2g of sodium hydroxide after the sodium polyacrylate is completely dissolved, and finally adding 150g of cerium oxide with a particle size of 1.0μm, stirring thoroughly and ultrasonicating for 30min. Example 4

[0029] The grinding and polishing method of fused quartz comprises the following steps: S1. A fused quartz disc with a diameter of 210 mm and a thickness of 50 mm is milled at a speed of 1400 r / min using a milling machine, and a single-sided milling is performed to remove 1.6 mm; S2 The milled disc is cleaned and then put into a grinder for grinding. Silicon carbide with a particle size of 40 μm is used as an abrasive and mixed with water at a ratio of 1:25. The grinding is performed at a speed of 15 r / min, and the single-side grinding size is 0.17 mm.

[0030] S3: The ground wafer is cleaned and then put into a high-polishing ring polishing machine for polishing. Cerium oxide with a particle size of 3.0 μm is used as an abrasive and mixed with water at a ratio of 1:60. The wafer is polished at a speed of 30 r / min until the double-sided PV accuracy is below 1 wavelength, i.e. 632.8 nm. S4. Clean the high-polished wafer, put it into the precision ring polishing machine for further polishing, use 0.5μm cerium oxide polishing liquid, and perform fine polishing at a speed of 1.5r / min until the double-sided PV precision is less than one tenth of the wavelength, i.e., 63.28nm; S5 cleans the polished wafer and then uses a digital interferometer to detect the surface shape. The PV accuracy is 52.653nm.

[0031] In this embodiment, the cerium oxide polishing liquid used in S4 is prepared as follows: 8g of sodium tripolyphosphate and 6g of polyvinyl alcohol are added to 4800g of deionized water with stirring, and after the sodium polyacrylate is completely dissolved, 6g of ammonia water and 3g of triethanolamine are added, and finally 600g of cerium oxide with a particle size of 0.5μm is added, and then ultrasonicated for 30min after sufficient stirring. Example 5

[0032] The grinding and polishing method of fused quartz comprises the following steps: S1. A fused quartz disc with a diameter of 190 mm and a thickness of 38 mm is milled at a speed of 1100 r / min using a milling machine, and a single-sided milling is performed to remove 1.6 mm; S2 The milled disc is cleaned and then put into a grinder for grinding. Silicon carbide with a particle size of 20 μm is used as an abrasive and mixed with water in a ratio of 1:18. The grinding is performed at a speed of 20 r / min, and the single-side grinding size is 0.21 mm.

[0033] S3: The ground wafer is cleaned and then put into a high-polishing ring polishing machine for polishing. Cerium oxide with a particle size of 2.3 μm is used as an abrasive and mixed with water at a ratio of 1:20. The wafer is polished at a speed of 20 r / min until the double-sided PV accuracy is below 1 wavelength, i.e. 632.8 nm. S4. Clean the high-polished wafer, put it into the precision ring polishing machine for further polishing, use 0.8μm cerium oxide polishing liquid, and perform fine polishing at a speed of 1.2r / min until the double-sided PV precision is less than one tenth of the wavelength, i.e., 63.28nm; S5 cleans the polished wafer and then uses a digital interferometer to detect the surface shape. The PV accuracy is 60.352nm.

[0034] In this embodiment, the preparation method of the cerium oxide polishing liquid used in S4 is as follows: 5g of sodium polymethacrylate, 6g of polyethylene glycol, and 2g of polyvinyl pyrrolidone are added to 4800g of deionized water with stirring, and after the sodium polyacrylate is completely dissolved, 16g of triethanolamine and 20g of sodium bicarbonate are added, and finally 600g of cerium oxide with a particle size of 0.5μm is added, and the mixture is thoroughly stirred and ultrasonicated for 30 minutes. Comparative Example 1

[0035] The grinding and polishing method of the prior art was used to carry out a grinding experiment, and the grinding and polishing method of the fused quartz was as follows: S1. Grind a fused quartz disc with a diameter of 100 mm and a thickness of 20 mm using a grinder, and remove 2.5 mm from one side by milling; S2: The ground wafer is cleaned and then placed in a double-sided ring polishing machine for further polishing, using a 1.0 μm cerium oxide polishing liquid, with an upper disc speed of 15 r / min, a lower disc speed of 20 r / min, and a polishing pressure of 36 kPa; S3 cleans the polished wafer and detects the surface shape through a digital interferometer after cleaning. The PV accuracy is 582.235nm.

[0036] Compared with the embodiments of the present invention, the PV accuracy of Comparative Example 1 is greatly different, which fully proves the advancement of the grinding and polishing method of the present invention.

Claims

1. A method for grinding and polishing fused quartz, characterized in that: The following steps are involved: S1. Milling: Use a milling machine to remove surface defects of the fused quartz component to approach the required thickness size; S2, grinding, after cleaning the milled components, put them into the ring grinder for further grinding to remove surface defects and reduce the damage layer; S3, high-speed ring polishing, after cleaning the ground components, put them into the high-speed ring polishing machine, and quickly polish them into a mirror surface, so that the accuracy of the double-sided PV is below 1 wavelength, i.e. 632.8nm; S4, precision ring polishing, after cleaning the components that have been polished by high speed, put them into the precision ring polishing machine to fine-tune the surface of the components, so that the double-sided PV accuracy is less than one tenth of the wavelength, that is, 63.28nm; S5. Clean the polished components.

2. The method for grinding and polishing fused quartz according to claim 1, wherein: In the step S1, the rotation speed of the grinding wheel of the milling machine is between 1000 r / min and 1400 r / min.

3. The method for grinding and polishing fused quartz according to claim 1, characterized in that: In the step S2, the abrasive used in the ring mill is a mixture of silicon carbide and water in a weight ratio of 1:15-25, wherein the particle size of the silicon carbide is 14 μm to 40 μm, and the speed of the ring mill is 10 r / min to 30 r / min.

4. The method for grinding and polishing fused quartz according to claim 1, wherein: In step S3, the high-speed ring polishing machine uses polyurethane as the polishing pad, and the abrasive used is a mixture of cerium oxide and water in a weight ratio of 1:20-60, wherein the particle size of cerium oxide is 2.0 μm to 3.0 μm, and the speed of the high-speed ring polishing machine is 12 r / min to 30 r / min.

5. The method for grinding and polishing fused quartz according to claim 1, characterized in that: In step S4, the precision ring polishing machine uses optical polishing asphalt as the polishing pad, uses cerium oxide with a particle size of 0.5 μm to 1.5 μm as the abrasive to prepare a cerium oxide polishing liquid, and the rotation speed is 0.5 r / min to 1.5 r / min.

6. The method for grinding and polishing fused quartz according to claim 5, characterized in that: The cerium oxide polishing liquid is composed of the following components in parts by weight: 1 to 10 parts of cerium oxide, 0.001 to 1 part of dispersant, 0.0001 to 1 part of pH regulator, and 80 to 98 parts of deionized water.

7. A method for grinding and polishing fused quartz according to claim 6, characterized in that: The dispersant is at least one of sodium pyrophosphate, sodium tripolyphosphate, sodium polymethacrylate, sodium polyacrylate, polyvinyl alcohol, polyethylene glycol, and polyvinyl pyrrolidone.

8. The method for grinding and polishing fused quartz according to claim 6, characterized in that: The pH regulator is at least one of sodium hydroxide, potassium hydroxide, ammonia water, triethanolamine, sodium carbonate and sodium bicarbonate.

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