A method for preparing a low-temperature sintered fused quartz hemispherical resonator

Abstract

This invention relates to a method for fabricating a low-temperature sintered fused silica hemispherical resonator, belonging to the field of inertial navigation technology. The method comprises four steps: preparation of glass slurry, photopolymerization molding, thermal debinding, and vacuum sintering. This method employs ultraviolet photopolymerization integral molding technology, effectively ensuring the precision and surface quality of the inner and outer walls of the resonator. Compared to traditional processing techniques, this method can sinter fused silica resonators at 650 °C with a surface roughness below 10 nm, offering advantages such as a simple process flow, low sintering temperature, high molding precision, and low manufacturing cost. This invention eliminates the need for high-temperature molding, reducing the heat load and process difficulty. By designing replaceable high-precision molds, this method possesses high flexibility and structural customization capabilities, making it suitable for manufacturing various complex fused silica microdevices, exhibiting good process compatibility and significant application value.

Description

Technical Field

[0001] This invention relates to the field of inertial navigation technology, specifically to a method for preparing a low-temperature sintered fused silica hemispherical harmonic oscillator. Background Technology

[0002] As the core sensor of high-precision inertial navigation systems, the resonant gyroscope plays an irreplaceable role in fields such as spacecraft attitude control, satellite precision positioning, deep-sea exploration, and strategic weapon guidance due to its extremely high precision, superior stability and reliability, and excellent resistance to shock and vibration. The hemispherical resonator is the core sensitive element of the resonant gyroscope. Fused silica glass, with its ultra-low coefficient of thermal expansion, extremely high quality factor, excellent elastic stability, and chemical inertness, is an ideal material for fabricating hemispherical resonators. The structural precision, surface quality, and material uniformity of the hemispherical resonator directly affect the frequency stability and quality factor of the device, placing extremely high demands on its manufacturing process.

[0003] Traditional processing methods such as machining, molding and sintering, or high-temperature blowing are commonly used to prepare quartz hemispherical resonators. Turning or grinding processes use rod-shaped quartz glass as raw material, involving precision turning, grinding, polishing, and heat treatment to manufacture hemispherical resonators. This process suffers from long cycle times, low degrees of freedom, and low processing efficiency, particularly struggling to achieve coordinated control of small size, thin-walled structures, and high concentricity, leading to significant performance fluctuations in the resonator. Molding and sintering requires densification at 1300 °C, a high temperature that limits its widespread adoption. High-temperature blowing processes use a mixture of oxygen and propane as fuel to generate molten quartz glass at 1600 °C, allowing the quartz resonator to be prepared under pressure. However, this process suffers from high melting temperatures and a limited range of resonator structures. Summary of the Invention

[0004] To overcome the above problems, this invention provides a novel method for preparing a low-temperature sintered fused silica hemispherical resonator. This technique involves irradiating a pre-filled glass slurry within a transparent mold with ultraviolet light, causing it to rapidly solidify. After solidification, the slurry undergoes heat treatment to remove organic components, followed by densification at 650 °C to obtain the fused silica glass resonator.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a fused silica hemispherical harmonic oscillator includes the following steps:

[0007] Step S01: Preparation of photocurable glass slurry. Methacrylic acid-modified nano-silica sol, plasticizer, photoinitiator, and polymerization inhibitor are mixed and stirred until homogeneous. The slurry is then obtained by ultrasonic dispersion and vacuum degassing.

[0008] Step S02: Photocuring. Prepare a release agent, apply it evenly to the inner cavity of the master mold, and then dry it. Inject a transparent material into the master mold and cure it to create the punch and die of the hemispherical resonator. Assemble the two into a mold. Inject glass slurry into the cavity of the hemispherical resonator mold, and then induce a polymerization reaction in the glass slurry with ultraviolet light to obtain the green body of the hemispherical resonator.

[0009] Step S03: Heat degreasing. Heat treatment removes organic matter from the green body, yielding a degreased green body;

[0010] Step S04: Vacuum sintering. Place the degreased blank in a tube furnace and evacuate to 1×10⁻⁶. −2 The fused silica hemispherical harmonic oscillator is obtained by sintering at 650 °C for mbar.

[0011] Furthermore, the plasticizers in step S01 include, but are not limited to, diethyl phthalate (DEP) or diethylene glycol dibenzoate (DEDB), the photoinitiators include, but are not limited to, diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (TPO) or phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure 819), and the polymerization inhibitors include, but are not limited to, hydroquinone (HQ).

[0012] Furthermore, to reduce the introduction of impurities, the plasticizer, photoinitiator, and polymerization inhibitor used in step S01 are of analytical grade.

[0013] Furthermore, in step S01, the average particle size of the nano-silica in the methacrylic acid-modified nano-silica sol is 5 to 20 nm. The methacrylic acid-modified nano-silica sol is heated at 65 °C for 20 h to remove excess solvent, thereby obtaining a methacrylic acid-modified nano-silica sol with a solid content of 75 wt%.

[0014] Furthermore, in step S01, the purity of the nano-silica used is greater than 99.99%.

[0015] Furthermore, in step S01, the plasticizer used includes at least one of diethyl phthalate (DEP) or diethylene glycol dibenzoate (DEDB), and the photoinitiator includes at least one of diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (TPO) or phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure 819).

[0016] Furthermore, in step S01, the glass slurry is prepared by mixing heat-treated methacrylic acid-modified nano-silica sol, plasticizer, photoinitiator, and polymerization inhibitor in a certain proportion. The mass fraction of the heat-treated methacrylic acid-modified nano-silica sol is 84.5~90 wt%, the mass fraction of the plasticizer is 9.9~15.4 wt%, the mass fraction of the photoinitiator is 0.1~0.25 wt% of the total mass of the glass slurry, and the mass fraction of the polymerization inhibitor is 0.1 wt%, and the sum of the mass fractions of all components is 100 wt%.

[0017] Furthermore, in step S01, the nano-silica particles are uniformly dispersed in the solvent by ultrasound to prepare a glass slurry. Preferably, the ultrasound frequency is 40 kHz and the time is 1 h. The uniformly dispersed slurry is placed in a vacuum chamber and treated at a vacuum degree of 0.1 mbar for 1 h to remove air bubbles from the slurry.

[0018] Furthermore, in step S02, the release agent used is composed of perfluorodecyltriethoxysilane and an alcohol solvent (such as ethanol or methanol) in a mass ratio of 1:2. After mixing, it is ultrasonically dispersed evenly, applied to the master mold, and then heated to 110 °C to dry for 30 min.

[0019] Furthermore, in step S02, the transparent mold used consists of two parts: a punch and a die.

[0020] Furthermore, in step S02, the quality and processing precision of the master mold directly affect the surface quality and structural precision of the final hemispherical resonator. The master mold should preferably be prepared using high-precision processing methods, including but not limited to machining or additive manufacturing. Subsequently, a transparent material is poured into the master mold, and after it solidifies, it is demolded to form the punch and die of the hemispherical resonator. The punch and die are made of transparent materials, including but not limited to polydimethylsiloxane (PDMS). To ensure the forming quality of the mold, the master mold must be made of a material with good high-temperature resistance and high deformation resistance, such as polytetrafluoroethylene (PTFE), metal materials, or ceramics.

[0021] Furthermore, in step S02, when the glass slurry is slowly injected into the mold, external field assistance such as ultrasonic vibration can be used to reduce the generation of air bubbles during the slurry injection process. The mold with the injected slurry is then left to stand for 2 to 4 hours.

[0022] Furthermore, in step S02, when using ultraviolet light for shaping, the wavelength of the ultraviolet light is selected to be 405 nm, the power is 75 W to 1000 W, and the light intensity is 10 to 400 mW / cm². 2 The curing time is 20 to 100 seconds.

[0023] Furthermore, in step S02, the cured mold is placed in a constant temperature drying oven and kept at 40 to 50 ℃ for 5 to 6 hours for demolding treatment to obtain the cured green blank.

[0024] Furthermore, in step S03, heat treatment is used for degreasing to remove organic matter from the green body. The heating rate for heat degreasing is 1 ℃ / min to 2 ℃ / min, with two holding intervals set at 170 to 292 ℃ and 420 to 520 ℃, respectively, and the holding time for each interval is 2 to 4 h.

[0025] Furthermore, in step S04, the degreased blank is placed in a tube furnace and evacuated to a vacuum of 1×10⁻⁶. -2 The temperature was first increased to 650 °C at 10 °C / min and held for 10 h. After sintering, the temperature was reduced to room temperature at 5 °C / min to obtain a fully dense fused silica hemispherical harmonic oscillator.

[0026] This invention is not only applicable to the preparation of fused silica harmonic oscillators, but can also be used to prepare other complex fused silica glass devices, such as microfluidic chips, compound eyes, and double-sided microlenses, by changing the mold.

[0027] Compared with existing technologies, the present invention has the following advantages:

[0028] 1. This invention uses sintering at 650 ℃, which reduces the sintering temperature compared to molding / blowing processes, avoiding the problems of high energy consumption and demanding equipment requirements associated with traditional high-temperature processes.

[0029] 2. The molding process of this invention relies on a high-precision transparent mold to achieve shape limitation, and has the ability to replicate structures with nanometer-level precision (less than 10nm) and high consistency. It is particularly suitable for the manufacture of hemispherical harmonic oscillators with extremely high requirements for structural symmetry and shell thickness consistency.

[0030] 3. Compared with traditional turning or grinding methods, this invention does not rely on high-precision CNC equipment and complex multi-round precision machining processes, and has a higher degree of manufacturing freedom. It can achieve coordinated control of thin-walled (300 to 700 μm) structures and high concentricity, and has the advantages of low cost, simple process and high processing efficiency.

[0031] 4. This invention utilizes the high surface energy characteristics of nanopowders to significantly reduce the temperature required for sintering densification, achieving efficient, energy-saving, and environmentally friendly production while ensuring device performance.

[0032] 5. This invention can support the molding of arbitrary aspherical curvature, microgroove arrays or irregular thin-walled structures through flexible design and rapid replication of the master mold, breaking through the geometric limitations of traditional processes and significantly improving processing flexibility. In addition to being used for the manufacture of fused silica hemispherical resonators, it is also suitable for the manufacture of other complex microstructure fused silica devices such as microlens arrays, compound eyes, microfluidic chips, and biomimetic structures. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of a fused silica hemispherical harmonic oscillator.

[0035] Figure 2 This is a schematic diagram of the female mold structure of the concave mold.

[0036] Figure 3 This is a schematic diagram of the female mold structure of the punch.

[0037] Figure 4 This is a schematic diagram of the transparent mold assembly structure.

[0038] In the figure, 1 is the concave mold, 2 is the convex mold, 3 is the convex mold of the transparent mold, 4 is the concave mold of the transparent mold, and 5 is the formed resonator. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] To further illustrate the present invention, the following detailed description, in conjunction with the accompanying drawings, will describe a method for preparing a low-temperature sintered fused silica hemispherical harmonic oscillator according to the present invention.

[0041] This application provides a method for preparing a low-temperature sintered fused silica glass hemispherical resonator. The method includes steps such as photopolymerization, debinding, and sintering, and has the advantages of high structural precision and strong process controllability.

[0042] refer to Figure 1The fused silica hemispherical harmonic oscillator prepared in the embodiments of this application.

[0043] refer to Figure 2 and Figure 3 In this embodiment of the application, a transparent material (such as polydimethylsiloxane) is poured into the concave mold 1 and the convex mold 2 as templates, and after curing, a transparent mold is produced.

[0044] refer to Figure 4 In this embodiment, after the transparent mold is assembled, the punch 3 and the die 4 are used to form the resonator 5.

[0045] This application provides a method for preparing a low-temperature sintered fused silica hemispherical harmonic oscillator, comprising the following steps:

[0046] Step S01: Preparation of photocurable glass paste.

[0047] The methacrylic acid-modified nano-silica sol was heated at 65 °C for 20 h to remove excess solvent, yielding a methacrylic acid-modified nano-silica sol with a solid content of 75 wt%. The average particle size of the nano-silica in the methacrylic acid-modified nano-silica sol was 5 to 20 nm, and the purity was greater than 99.99%.

[0048] The plasticizer and photoinitiator are of analytical grade or higher purity.

[0049] The glass slurry is prepared by mixing heat-treated methacrylic acid-modified nano-silica sol, plasticizer, photoinitiator, and polymerization inhibitor in a certain proportion. The mass fraction of the heat-treated methacrylic acid-modified nano-silica sol is 84.5~90 wt%, the mass fraction of the plasticizer is 9.9~15.4 wt%, the mass fraction of the photoinitiator is 0.1~0.25 wt% of the total mass of the glass slurry, and the mass fraction of the polymerization inhibitor is 0.1 wt%, and the sum of the mass fractions of all components is 100 wt%.

[0050] During the slurry mixing process, ultrasonic waves were used to disperse the silica particles. The ultrasonic frequency was set to 40 kHz, and the treatment time was 1 h to ensure uniform dispersion of the silica particles in the slurry. Subsequently, the resulting slurry was placed in a vacuum chamber and treated under a vacuum of 0.1 mbar for 1 h to remove air bubbles from the slurry.

[0051] Step S02: Photocuring.

[0052] A release agent is prepared by mixing perfluorodecyltriethoxysilane with an alcohol solvent (such as ethanol or methanol) in a mass ratio of 1:2. The release agent is then evenly applied to the inner cavity of the mold and dried at 110 °C for 30 min to form a release layer.

[0053] A transparent material is injected into the master mold and cured. After demolding, the punch and die of the hemispherical resonator are made. The transparent material used in the mold includes, but is not limited to, polydimethylsiloxane.

[0054] The glass slurry is slowly injected into the mold, and external field assistance such as ultrasonic vibration is used during the injection process to reduce the generation of air bubbles. After the injection is completed, the mold is left to stand for 2 to 4 hours to ensure that the slurry is evenly distributed.

[0055] Photocuring was performed using a 405 nm ultraviolet light source with an intensity of 10 to 400 mW / cm². 2 The irradiation time is 20 to 100 seconds to induce polymerization of the glass slurry. After curing, the mold is placed in a constant temperature drying oven and kept at 40 to 50 °C for 5 to 6 hours for demolding to obtain the cured green body.

[0056] Step S03: Heat degreasing.

[0057] Organic matter in the green body is removed by heat treatment degreasing. The heating rate for heat degreasing is 1 ℃ / min to 2 ℃ / min, with two holding intervals set at 170 to 292 ℃ and 420 to 520 ℃, and the holding time for each interval is 2 to 4 h.

[0058] Step S04: Vacuum sintering.

[0059] The degreased blanks are placed in a tube furnace and evacuated to a vacuum of 1×10⁻⁶. -2 The temperature was increased to 650 °C at 10 °C / min and held for 10 h. After sintering, the temperature was decreased to room temperature at 5 °C / min to obtain a dense fused silica hemispherical harmonic oscillator.

[0060] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention, or modify it into equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a low-temperature sintered fused silica hemispherical harmonic oscillator, characterized in that, Includes the following steps: Step S01: Preparation of photocurable glass slurry. Methacrylic acid-modified nano-silica sol, plasticizer, photoinitiator, and polymerization inhibitor are mixed and stirred until homogeneous. The mixture is then subjected to ultrasonic dispersion and vacuum degassing to obtain the glass slurry. Step S02: Photocuring. Prepare a release agent, apply it evenly to the inner cavity of the master mold, and then dry it. Inject a transparent material into the master mold and cure it to create the punch and die of the hemispherical resonator. Assemble the two into a mold. Inject glass slurry into the cavity of the hemispherical resonator mold, and then induce a polymerization reaction in the glass slurry with ultraviolet light to obtain the green body of the hemispherical resonator. Step S03: Heat degreasing. Heat treatment removes organic matter from the green body, yielding a degreased green body; Step S04: Vacuum sintering. Place the degreased blank in a tube furnace and evacuate to 1×10⁻⁶. -2 The fused silica hemispherical harmonic oscillator is obtained by further heat treatment at 650 °C, followed by a process using mbar.

2. The method for preparing a fused silica hemispherical harmonic oscillator according to claim 1, characterized in that, In step S01, the plasticizer includes, but is not limited to, diethyl phthalate (DEP) or diethylene glycol dibenzoate (DEDB), the photoinitiator includes, but is not limited to, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) or phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure 819), and the polymerization inhibitor includes, but is not limited to, hydroquinone (HQ).

3. The method for preparing a fused silica hemispherical harmonic oscillator according to claim 1, characterized in that, In step S01, the average particle size of the nano-silica in the methacrylic acid modified nano-silica sol is 5 to 20 nm. The methacrylic acid modified nano-silica sol is heated at 65 °C for 20 h to remove excess solvent, obtaining a methacrylic acid modified nano-silica sol with a solid content of 75 wt%.

4. The method for preparing a fused silica hemispherical harmonic oscillator according to claim 2, characterized in that, In step S01, the glass slurry is prepared by mixing heat-treated methacrylic acid-modified nano-silica sol, a plasticizer, a photoinitiator, and a polymerization inhibitor. The plasticizer includes at least one of diethyl phthalate or diethylene glycol dibenzoate, and the photoinitiator includes at least one of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide or phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide. The mass fraction of the heat-treated methacrylic acid-modified nano-silica sol is 84.5–90 wt%, the mass fraction of the plasticizer is 9.9–15.4 wt%, the mass fraction of the photoinitiator is 0.1–0.25 wt% of the total mass of the glass slurry, and the mass fraction of the polymerization inhibitor is 0.1 wt%, with the sum of the mass fractions of all components being 100 wt%. The prepared glass slurry is ultrasonically dispersed at a frequency of 40 kHz for 1 h.

5. The method for preparing a fused silica hemispherical harmonic oscillator according to claim 1, characterized in that, In step S02, the master mold is prepared using high-precision machining methods, including but not limited to machining or additive manufacturing. The master mold must be made of materials with good high-temperature resistance and high deformation resistance, including but not limited to polytetrafluoroethylene (PTFE), metal materials, or ceramic materials, and the mold is polished to achieve a surface roughness of less than 20 nm. The resonator mold consists of two parts: a punch and a die, both of which are made from the master mold using transparent materials, including but not limited to polydimethylsiloxane.

6. The method for preparing a fused silica hemispherical harmonic oscillator according to claim 1, characterized in that, In step S02, the release agent used is composed of perfluorodecyltriethoxysilane and an alcohol solvent (such as ethanol or methanol) in a mass ratio of 1:

2. The prepared release agent is evenly applied to the inner cavity of the mold and then dried at 110 °C for 30 min.

7. The method for preparing a fused silica hemispherical harmonic oscillator according to claim 1, characterized in that, In step S02, when the glass slurry is injected into the mold, the generation of bubbles is reduced by external field assistance such as ultrasonic vibration. Then, the mold with the injected slurry is left to stand for 2 to 4 hours. Ultraviolet light is used for molding, with an ultraviolet wavelength of 405 nm, a power of 75 to 1000 W, and a curing time of 20 to 100 s.

8. The method for preparing a fused silica hemispherical harmonic oscillator according to claim 1, characterized in that, In step S03, heat treatment is used to degrease and remove organic matter from the green body. The heating rate for heat degreasing is 1 ℃ / min to 2 ℃ / min, and two holding intervals are set, namely 170 to 292 ℃ and 420 to 520 ℃, with a holding time of 2 to 4 h for each interval.

9. The method for preparing a fused silica hemispherical harmonic oscillator according to claim 1, characterized in that, In step S04, the degreased blank is placed in a tube furnace and evacuated to a vacuum of 1×10⁻⁶. -2 The temperature was increased to 650 °C at a rate of 10 °C / min and held for 10 h. After sintering, the temperature was decreased to room temperature at a rate of 5 °C / min to obtain a fully dense fused silica hemispherical harmonic oscillator. The sintering temperature of the hemispherical harmonic oscillator is only 650 °C, the surface roughness can reach below 10 nm, the wall thickness is 300 to 700 μm, and the diameter is 10 to 40 mm.

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