Low-refractive, erosion-resistant skin glass, method for its production and use in optical fiber inverter

Abstract

The application relates to the fields of optical fiber image transmission and glass materials, in particular to a low-refraction anti-erosion skin layer glass, a preparation method thereof and application of the glass in an optical fiber inverter. The glass is composed of the following raw materials in terms of mass percentage of the mixture powder: 44-65% of SiO2, 5-16.5% of Al(OH)3, 2-7% of Na2CO3, 14-26.5% of KNO3, 5-13% of H3BO3, 0.5-5% of an alkaline earth metal carbonate, 0.1-1% of CeO2 and 0.1-1.5% of YF3, and the total amount of the silica, the boric acid and the aluminum hydroxide ranges from 69% to 81%. The glass has the characteristics of low refractive index (less than 1.48), good matching with high refractive index core material, excellent anti-erosion and chemical stability and environmental protection and no heavy metal, and can effectively optimize the production process and reduce the cost while improving the performance of the optical fiber device and prolonging the service life.

Description

Technical Field

[0001] This invention relates to the fields of optical fiber imaging and glass materials, and particularly to a low-refractive-index, corrosion-resistant corrugated glass, its preparation method, and its application in optical fiber image inverters. Background Technology

[0002] In the 1950s, a major breakthrough in optical fiber technology laid the foundation for the development of fiber optic image reversals. At that time, optical fibers with a double-layer structure of a high-refractive-index core and a low-refractive-index skin utilized the principle of total internal reflection to achieve long-distance, low-loss transmission of light within the fiber. This key design is the core principle behind the image transmission capabilities of fiber optic image reversals. Later, to meet the specific requirement of "image reversal," engineers used a special arrangement process during fabrication to mirror-reverse the pixel distribution at both ends of the fiber, achieving 180° image inversion transmission and successfully fabricating the fiber optic image reversal device.

[0003] With the rapid development of military, medical, and other fields, higher and more stringent requirements have been placed on image transmission technology. In the field of industrial inspection, as industrial equipment becomes larger, more precise, and more complex, the demand for inspection of the internal structure of equipment is increasing. For example, critical components such as turbine blades and combustion chambers inside large equipment like aero engines and gas turbines are prone to cracks, wear, and carbon buildup during long-term operation. If these problems are not detected and addressed in time, they may lead to serious safety accidents. Traditional inspection methods often require disassembling the equipment, which is not only costly and inefficient but may also cause secondary damage to the equipment. Fiber optic image reversers, used in conjunction with industrial endoscopes, can penetrate into the confined spaces inside equipment to achieve non-destructive inspection of critical components. At the same time, the complex and diverse industrial inspection environment, such as high temperature, high pressure, and corrosive gases, places higher demands on the high temperature resistance, corrosion resistance, and high pressure resistance of fiber optic image reversers, driving technological innovation in material selection, structural design, and sealing processes.

[0004] Alkali metal ions (Na) in traditional sodium-calcium based glass + Ca 2+It readily reacts with corrosive media to form soluble silicates, reducing strength and causing surface roughening (appearing a white, hazy corrosion layer), thus damaging the light reflection interface. In oil and gas pipeline inspection, this type of corrosion can reduce the coating thickness by 2-3 μm within 3 months, leading to light crosstalk. Therefore, improving the corrosion resistance and strength of low-refractive-index coating glass is currently the best solution to the aforementioned light crosstalk problem. Generally, increasing the content of Al2O3 and B2O3 or introducing corrosion-resistant elements such as zirconium and titanium can improve chemical stability and strength. However, excessive addition of corrosion-resistant elements can cause crystallization during the drawing process or brittleness after drawing, reducing product quality. Therefore, new products must ensure improved glass strength and corrosion resistance without affecting its processing performance, which is currently a key issue in the development of new materials. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a low-refractive-index, corrosion-resistant skin glass, its preparation method, and its application in fiber optic image converters. This glass has a refractive index not exceeding 1.48, possesses suitable thermal expansion characteristics and a suitable softening temperature range, making it suitable for the fabrication of fiber optic panels and optical fibers. Crucially, its viscosity characteristics are well-matched with core glass materials (especially high-refractive-index core materials with a refractive index ≥ 1.8), thereby optimizing the fiber drawing process and exhibiting excellent processing adaptability and forming compatibility. Furthermore, this glass combines excellent chemical stability and mechanical strength, endowing it with superior corrosion resistance. This not only significantly extends the service life of the fiber optic image converter and reduces resource consumption caused by frequent component replacements but also helps maintain the long-term stable optical performance of the device. Taking outdoor optical monitoring equipment as an example, under complex and changing natural environmental conditions, this low-refractive-index skin glass can effectively resist corrosive factors such as wind, sand, and rain, ensuring the continuous normal operation of the equipment and image clarity.

[0006] Specifically, the technical solution provided by this invention is as follows:

[0007] In a first aspect, the present invention provides a low-refractive-index erosion-resistant glass comprising, by weight percentage of the following raw materials: 44-65% SiO2, 5-16.5% Al(OH)3, 2-7% Na2CO3, 14-26.5% KNO3, 5-13% H3BO3, 0.5-5% alkaline earth metal carbonates, 0.1-1% CeO2, and 0.1-1.5% YF3, wherein the alkaline earth metal carbonates are selected from at least one of CaCO3 and MgCO3, and the total amount of silica, boric acid, and aluminum hydroxide introduced ranges from 69-81%.

[0008] Introducing silicon oxide (Silica) into glass can lower the refractive index by appropriately increasing its content. However, this increase in content also raises the glass viscosity (softening point), affecting its compatibility with the core glass. Similarly, introducing yttrium fluoride (YF3) can also lower the refractive index, but this increase in YF3 content also raises the coefficient of thermal expansion, further impacting compatibility with the core glass. This is a major problem in the current preparation of low-refractive-index glasses. Therefore, solving these problems and improving compatibility with the core glass is the key technical challenge this invention aims to address. The main basic component of this invention is silicon oxide, with SiO2 introduced to form the glass network structure. Boric acid is introduced into the network intermediate boron oxide (B2O3), aluminum hydroxide into aluminum oxide (Al2O3), and carbonates or nitrates of alkali metals and alkaline earth metals are introduced into alkali metal oxides (K2O, Na2O) and alkaline earth metal oxides (at least one of CaO and MgO). Cerium oxide can be selectively introduced into CeO2.

[0009] In embodiments of the present invention, SiO2 is the basic framework of the glass network structure, introduced by silicon dioxide, and is the main component of the low-refractive-index, corrosion-resistant skin glass. In the glass material of the present invention, the mass content of SiO2 is 44-65% to maintain the tensile strength, chemical stability, corrosion resistance, viscosity, and coefficient of thermal expansion of the glass. In some embodiments of the present invention, the mass content of SiO2 is 42-65%, 44-60%, 45-60%, 50-60%, 55-60%, 60-65%, 60-63%, 55-63%, 50-56%, etc. Preferably, the mass content of SiO2 is 49.5-60%, 57.8-61.7%, 60.0-64.8%, 44.7-52.7%, 46.8-52.7%, or 56.8-60.7%.

[0010] B₂O₃, as a glass-forming oxide, can form glass on its own. In silicate glasses, boron (B) can partially replace silicon (Si) to form a network structure. Furthermore, B₂O₃ acts as a flux in glass, reducing its high-temperature viscosity, saving costs, and facilitating production. The appropriate introduction of boron oxide can improve the chemical stability of the glass; however, with increasing B₂O₃ content, a "boron anomaly" occurs, leading to decreased chemical stability and an increased devitrification range. Therefore, its dosage should be strictly controlled during preparation. Thus, in the glass material provided by this invention, B₂O₃ is introduced from boric acid, with a boric acid mass content of 5-16.5%. In some embodiments of this invention, the boric acid mass content is 5-6.5%, 5-6.9%, 5-7.3%, 5.2-8.2%, 6.9-8%, 6.9-8.2%, 6.2-9.9%, 7.2-16%, 7.2-11%, 7.2-10%, etc. Preferably, the boric acid content is 5.2~6.7% or 6.1~6.9% or 6.5~7.9% or 7.2~8% or 5.8~7.2% or 6.9~7.2% or 7.2~7.8%.

[0011] CeO2 has a variable valence state in this invention (Ce 3+ and Ce 4+ Ce, in a high-temperature clarification state 4+ It will be reduced to Ce 3+ Simultaneously, it releases oxygen and absorbs other tiny bubbles to form larger bubbles, which are then expelled, achieving the effect of clarifying glass. Meanwhile, Ce... 4+ It can combine with non-bridging oxygen in the glass network, reducing hydroxyl (-OH) and easily soluble ions (such as Na+) on the glass surface. + This improves the glass's resistance to corrosion. Additionally, trace amounts of CeO2 can enhance the glass's hardness, impact resistance, and thermal shock resistance. However, excessive introduction of CeO2 can form tiny CeO2 particles within the glass, causing it to appear translucent and milky white through light scattering, thus reducing its transmittance. Therefore, the CeO2 content in the glass material described in this invention is controlled at 0.01~0.5% (mass percentage), introduced in the form of cerium oxide, with a mass percentage range of 0.1~1%. In some embodiments of this invention, the mass content of CeO2 is 0.1~0.2%, 0.1~0.3%, 0.1~0.5%, 0.5~0.6%, 0.5~0.7%, 0.5~0.8%, 0.5~0.9%, etc. More preferably, the mass content of CeO2 is 0.1~0.2% or 0.3~0.7%.

[0012] Na₂O and K₂O are oxides on the glass network. Alkali metal ions readily move and diffuse within the glass, reducing the viscosity of the glass during high-temperature melting, making it easier to melt, and thus acting as excellent fluxes. They also increase the glass's coefficient of thermal expansion. In the glass material described in this invention, sodium carbonate is introduced into Na₂O, with a mass content of 2-7%; potassium nitrate is introduced into K₂O, with a mass content of 14-26.5%. By adjusting the potassium nitrate / sodium carbonate ratio, firstly, the gas ratio of the batch is controlled between 15-20%, thereby accelerating the melting and clarification of the glass melt, improving production efficiency and product quality; secondly, sodium carbonate and potassium nitrate are chosen primarily because sodium carbonate is low-cost and has high fluxing efficiency, enabling rapid and economical melting of the glass's basic network. During the melting process, potassium nitrate utilizes its continuous and stable oxidizing properties to eliminate bubbles, prevent the reduction of variable-valence elements, and the K₂O left after decomposition has a "mixed alkali effect," thereby strengthening the glass network and improving its corrosion resistance. In some embodiments of this invention, the total mass of sodium carbonate and potassium nitrate is ≤33%, preferably 17-33%. In some embodiments of the present invention, the mass content of sodium carbonate may be selected from the following ranges: 2-5%, 2-4%, 2-3%, 2-6.5%, 2-6%, 2-5%, 3-6.5%, 4-6.5%, 5-6.5%, 6-6.5%, 6.3-6.5%, etc., and the mass content of potassium nitrate may be selected from the following ranges: 14-28.3%, 14-26.3%, 14-25.5%, 14-24.9%, 14.9-26.5%, 14.9-19.6%, 14.9-19.3%, 15-19.6%, 15-19.3%, 16-28.3%, 16-19.6%, 16-19.3%, 16.3-19%, 16-19.3%, 18-19.3%, etc.

[0013] Al₂O₃, as a network intermediate for forming glass structures, significantly improves the mechanical strength and resistance to deformation of glass by altering the network structure. Simultaneously, Al… 3+The combination with non-bridging oxygen bonds can "fix" alkali metal ions in the glass, preventing them from accumulating on the glass surface and reacting with the external environment. However, excessive introduction will significantly reduce the glass's properties, increase its viscosity, and increase the difficulty of melting. In the glass material described in this invention, aluminum hydroxide is introduced into Al2O3 by mass percentage. Compared with Al2O3, aluminum hydroxide is easier to decompose and can effectively reduce the clarifying viscosity. The mass content of aluminum hydroxide is 5-16.5%. In some embodiments of this invention, the mass content of aluminum hydroxide is 5-5.4%, 5-5.7%, 5-6.3%, 5-7%, 5-7.9%, 6-7.9%, 7.9-10%, 7.1-9.1%, 7.1-10.9%, 10.9-14%, 14.9-15.1%, and 15.1-16.5%, etc. In some embodiments of this invention, the mass content of aluminum hydroxide is 5.1-7.1% or 14.1-16.5%.

[0014] In order to improve the corrosion resistance of the glass, it is necessary to improve the density of the glass structure. Preferably, the total mass content of silicon dioxide, boric acid and aluminum hydroxide is 69-81%, more preferably 70-75%, 70-73%, 71-80%, or 75-80%, etc.

[0015] YF3 acts as a flux, effectively reducing processing costs. Under high temperatures, it slowly decomposes, releasing low-boiling-point fluorine-containing gases that fuse with tiny bubbles in the glass, causing them to rise to the surface and clarify the glass. Furthermore, the fluorine in YF3... - With its low refractive index, adding an appropriate amount of YF3 can reduce the glass's refractive index; however, excessive introduction will increase the glass's coefficient of thermal expansion, reducing its compatibility with the core material. Y... 3+ It possesses a high electric field strength, thereby making the glass network denser and improving its corrosion resistance. In the glass material of the present invention, yttrium fluoride is introduced into YF3 at a content of 0.1-1.5% by mass percentage. In some embodiments of the present invention, this content can be selected from the following ranges: 0.1-1.3%, 0.1-0.5%, 0.1-1.3%, 0.1-1.2%, 0.2-1.5%, 0.1-0.2%, 0.1-0.3%, 0.2-0.5%, 0.5-1.5%, 0.2-1.3%, 0.3-1.5%, 0.3-0.5%, 0.5-1.2%, etc. Preferably, the mass content of YF3 is 0.1-0.2%, 0.1-0.3%, 0.2-1.5%, or 0.3-1.5%.

[0016] In this invention, the addition of at least one alkaline earth metal carbonate selected from CaCO3 and MgCO3 will greatly reduce the phase separation tendency of the glass. Therefore, the glass material of this invention needs to contain at least one alkaline earth metal carbonate selected from CaCO3 and MgCO3, and its mass content is 0.5~5%.

[0017] For example, in some embodiments of the present invention, the alkaline earth metal carbonate contains at least MgCO3, and its mass content is 0-2%; more preferably, the mass content of MgCO3 is 0-0.5% or 0.1-0.5% or 0.2-0.5% or 0.5-1.5% or 0.3-0.7%.

[0018] For example, in some embodiments of the present invention, the alkaline earth metal carbonate contains at least CaCO3, and its mass content is 0-2%; preferably, the mass content of CaCO3 is 0 or 0-1% or 1-1.2% or 0.5-1% or 1.7-2.0%.

[0019] As a preferred example, in the above embodiments of the present invention, the alkaline earth metal carbonate can be MgCO3, or a combination of CaCO3 and MgCO3. In some embodiments, the content of the alkaline earth metal carbonate is 1.5-2%, 2-5%, or 2.2-2.8% by mass percentage.

[0020] The various specific technical features described in the above embodiments of the present invention can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0021] Unless otherwise specified, the numerical ranges described in this invention include all values ​​within this range, and also include any range of values ​​formed by any two values ​​within this range. For example, 0.1% to 0.5% CeO2, this numerical range includes all values ​​between 0.1% and 0.5%, and also includes any range of values ​​formed by any two values ​​within this range (e.g., 0.11% and 0.45%) (0.11%-0.45%). Different values ​​of the same indicator appearing in all embodiments of this invention can be arbitrarily combined to form a range value.

[0022] In some embodiments of the present invention, the refractive index of the glass is ≤1.48. The low refractive index results in a larger angle of light reception θ, allowing more light to enter the optical fiber and thus exhibiting good refractive properties. In some embodiments, the refractive index of the glass of the present invention is ≤1.47.

[0023] In some embodiments of the present invention, the glass material has suitable glass transition temperature Tg, and / or expansion softening temperature Tf, and / or softening point temperature Ts, and / or coefficient of thermal expansion. More suitable parameters are Tg ≤ 580℃, Tf ≤ 670℃, Ts ≤ 775℃, and a coefficient of thermal expansion of (80~87)×10⁻⁶ at 20℃~300℃. -7 / ℃.

[0024] In a second aspect of the present invention, a method for preparing the low-refractive anti-erosion skin glass described in the first aspect of the present invention is provided, comprising the following steps: mixing raw materials in proportion, melting the raw materials at high temperature, stirring to assist clarification and homogenization, drawing and forming, and high-precision annealing to prepare a glass blank.

[0025] In this invention, in some embodiments, the high-temperature melting temperature is 1350~1550℃, the drawing temperature is 1050~1350℃, and the annealing temperature is 500~600℃. Based on the raw materials disclosed in the first aspect of this invention, the glass material prepared within this temperature range possesses stable properties, including but not limited to good refractive properties, good heat resistance, good processability, and good chemical stability. Of course, it is understood that within this temperature range, higher temperatures can shorten the preparation process compared to lower temperatures. If it is necessary to minimize time costs, those skilled in the art can select a relatively higher temperature within the temperature range disclosed in this invention.

[0026] In a third aspect, the present invention provides an application of the low-refractive-index, corrosion-resistant cladding glass described in the first aspect in an optical fiber image inverter.

[0027] The beneficial effects of this invention are as follows: This invention provides a low-refractive-index, corrosion-resistant glass with excellent corrosion resistance. While maintaining a low refractive index (≤1.48), this glass also possesses suitable thermal expansion coefficient and softening point temperature, making it widely applicable in the fabrication of optical devices such as fiber optic cones. In a saturated water vapor environment chamber with 90% relative humidity, the temperature was raised to 40℃, and then cyclically repeated every 1 hour between 40℃ and 50℃. After 15 cycles of corrosion testing, the turbidity change (turbidity difference) of the glass was less than 0.3, indicating excellent chemical stability and resistance to environmental corrosion. It can withstand the long-term effects of rain, wind, sand, and other natural factors, maintaining stable optical performance and high mechanical strength. The glass transition temperature Tg≤580℃, Tf≤670℃, and Ts≤775℃, and the thermal expansion coefficient in the range of 20℃ to 300℃ is (80~87)×10⁻⁶. -7With a temperature of / ℃, it possesses excellent thermal processing characteristics and molding adaptability, making it suitable for manufacturing large-size devices. This low-refractive-index, corrosion-resistant skin glass not only has good compatibility with the core glass (especially high-refractive-index core materials), which is beneficial for the fiber optic taper drawing process, but also effectively increases the numerical aperture of the fiber optic taper, thereby significantly improving device performance. Simultaneously, the glass of this invention does not contain heavy metal oxides, is environmentally friendly, meets environmental protection requirements, and can reduce production costs to a certain extent. Compared with similar materials at home and abroad, the corrosion-resistant glass material described in this invention has shown significant advantages in overall performance. Attached Figure Description

[0028] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation thereof. Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings, wherein: Figure 1 This is a comparison chart of the transmittance (560nm) of the glass material before and after 15 cycles of erosion experiment in Example 3 of the present invention. Detailed Implementation

[0029] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods or product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0031] In a first aspect, the present invention provides a high-strength, low-refractive-index skin glass material that can be used as a skin glass. It is composed of the following raw materials by mass percentage: 44-65% SiO2, 5-16.5% Al(OH)3, 2-7% Na2CO3, 14-26.5% KNO3, 5-13% H3BO3, 0.5-5% alkaline earth metal carbonates, 0.1-1% CeO2, and 0.1-1.5% YF3. The alkaline earth metal carbonates are selected from at least one of CaCO3 and MgCO3. The total amount of silica, boric acid, and aluminum hydroxide introduced ranges from 69-81%. The glass material of the present invention has suitable coefficients of thermal expansion and softening temperatures, good processability and adaptability, and can be used as a skin glass material for the fabrication of optical fiber image inverters. The resulting optical fiber image inverter also possesses good corrosion resistance, fundamentally meeting the requirements for applications in extreme environments.

[0032] Specifically, when the high-strength, low-refractive-index, corrosion-resistant glass material of the present invention is composed of the above-mentioned components, in some embodiments of the present invention, the refractive index of the glass material is ≤1.48; in some embodiments of the present invention, the glass transition temperature Tg of the glass material is ≤580℃; in some embodiments of the present invention, the expansion softening temperature Tf of the glass material is ≤670℃; in some embodiments of the present invention, the softening point temperature Ts of the glass material is ≤775℃, matching the core glass material; in some embodiments of the present invention, the coefficient of thermal expansion of the glass material is (80~87)×10 at 20℃~300℃. -7 / ℃; In some embodiments of the present invention, the glass material exhibits a turbidity difference of less than 0.3 before and after 15 cycles of etch tests; and in some embodiments of the present invention, the glass material of the present invention simultaneously possesses the aforementioned excellent properties, namely, a refractive index ≤1.48, a glass transition temperature Tg ≤580℃, an expansion softening temperature Tf ≤670℃, a softening point temperature Ts ≤775℃, and a coefficient of thermal expansion of (80~87)×10. -7 The glass turbidity difference before and after 15 cycles of etching experiments was less than 0.3, exhibiting superior overall performance and making it particularly suitable for the fabrication of erosion-resistant optical components or instruments.

[0033] Furthermore, the low-refractive-index corrosion-resistant glass material of this invention can be prepared by the following method: raw materials are mixed in a specified ratio, the mixture is melted at a high temperature of 1350-1550℃, clarified with auxiliary stirring, mechanically drawn at 1050-1350℃, and annealed at 500-600℃ to obtain the environmentally friendly low-refractive-index corrosion-resistant glass material. This method possesses process stability, and the glass material prepared within this temperature range exhibits stable properties, including but not limited to good refractive properties, good heat resistance, good processability, and good corrosion resistance. Of course, it is understood that within this temperature range, higher temperatures can shorten the preparation process compared to lower temperatures. If it is necessary to minimize time costs, those skilled in the art can select a relatively higher temperature within the temperature range disclosed in this invention.

[0034] Furthermore, in order to better illustrate the present invention, the present invention will be further described below with reference to specific examples.

[0035] Example 1 The low-refractive-index corrosion-resistant glass material of this embodiment is composed of the following batch components by mass percentage: 50.3% SiO2, 11.8% Al(OH)3, 0.2% MgCO3, 2.8% Na2CO3, 0.6% CaCO3, 26.3% KNO3, 7.5% H3BO3, 0.4% CeO2, and 0.1% YF3.

[0036] The method for preparing the low-refractive-index corrosion-resistant glass material in this embodiment is as follows: after mixing the various glass raw materials in proportion, the batch is melted at a high temperature of 1525℃, clarified by auxiliary stirring, mechanically drawn at 1255℃, and annealed at 555℃ to obtain the final product.

[0037] The refractive index of the glass samples was tested using a Metricon Model 2010 / M prism coupling tester. During the test, a beam of parallel light was incident perpendicularly onto the incident surface of a V-prism. If the refractive index of the sample matches that of the V-prism, the light will pass through the interface without deflection; if there is a difference, the light will refract. The refractive index of the sample can be obtained by measuring the deflection angle between the incident and outgoing light and calculating it according to the law of refraction. The test was conducted at room temperature, conforming to the requirements of GB / T7962.1-2010 standard.

[0038] The coefficient of linear expansion of glass samples was determined using a Netzsch DIL 402 thermal dilatometer. Samples were pre-processed into cylinders of Φ6 mm × 50 mm, with both ends ground and polished to ensure flatness and parallelism. The temperature was increased at a rate of 5 °C / min, with data acquisition intervals of 20 ms. Temperature versus sample length curves were recorded, and the data were processed using the tangent method to determine the glass transition temperature Tg and expansion softening temperature Tf. The experimental procedure followed GB / T 7962.16–2010 standard.

[0039] The softening point temperature of glass was measured using a PPV-1000 / 1200 plate viscometer manufactured by Orton, USA. The sample was prepared as a Φ6 mm × 6 mm cylinder with smooth, parallel end faces. During testing, the sample was placed between two heat-resistant alloy discs, each 44 mm in diameter and 6 mm thick, connected to the probe rod. Thin platinum sheets, approximately 40 mm in diameter and 0.001 inches thick, were placed between the sample and the upper and lower metal plates to facilitate sample loading and prevent adhesion. The softening point of the glass was determined by monitoring the probe displacement under specific heating conditions. This method was performed according to GB / T 7962.16-2010.

[0040] The low-refractive-index corrosion-resistant glass material prepared by the method in this embodiment has a refractive index of 1.47. After 15 cycles of programmed corrosion testing (in a saturated water vapor environment chamber with a relative humidity of 90%, the temperature is raised to 40°C, and then alternated between 40°C and 50°C every 1 hour), the turbidity difference of the glass is less than 0.3, the transmittance is 90% (a decrease of 1.4%), the glass transition temperature Tg is 563°C, the expansion softening temperature Tf is 652°C, the softening point temperature Ts is 750°C, and the coefficient of thermal expansion is 82.8 × 10⁻⁶. -7 With a temperature of / ℃, it has good processability and adaptability, and can be used as a glass material for the fabrication of optical fiber image converters. The resulting optical fiber image converter also has good corrosion resistance, which can fundamentally meet the requirements of extreme environment applications.

[0041] Example 2 The low-refractive-index corrosion-resistant glass material of this embodiment is composed of the following batch components by mass percentage: 54.5% SiO2, 7.5% Al(OH)3, 0.4% MgCO3, 5.1% Na2CO3, 1.2% CaCO3, 22.8% KNO3, 8.1% H3BO3, 0.2% CeO2, and 0.2% YF3.

[0042] The method for preparing the low-refractive-index corrosion-resistant glass material in this embodiment is as follows: after mixing the various glass raw materials in proportion, the batch is melted at a high temperature of 1525℃, clarified by auxiliary stirring, mechanically drawn at 1255℃, and annealed at 555℃ to obtain the final product.

[0043] The low-refractive-index erosion-resistant glass material prepared by the method in this embodiment has a refractive index of 1.48. After 15 cycles of erosion testing, the difference in glass turbidity is less than 0.3, and the transmittance is 90.2% (a decrease of 1.2%). Figure 1 As shown, the glass transition temperature Tg is 566℃, the expansion softening temperature Tf is 632℃, the softening point temperature Ts is 740℃, and the coefficient of thermal expansion is 82.3×10⁻⁶. -7 With a temperature of / ℃, it has good processability and adaptability, and can be used as a glass material for the fabrication of optical fiber image converters. The resulting optical fiber image converter also has good corrosion resistance, which can fundamentally meet the requirements of extreme environment applications.

[0044] Example 3 The low-refractive-index corrosion-resistant glass material of this embodiment is composed of the following batch components by mass percentage: 60.0% SiO2, 5.2% Al(OH)3, 0.5% MgCO3, 6.5% Na2CO3, 2.0% CaCO3, 19.1% KNO3, 6.5% H3BO3, 0.1% CeO2, and 0.1% YF3.

[0045] The method for preparing the low-refractive-index corrosion-resistant glass material in this embodiment is as follows: after mixing the various glass raw materials in proportion, the batch is melted at a high temperature of 1545℃, clarified by auxiliary stirring, mechanically drawn at 1305℃, and annealed at 560℃ to obtain the final product.

[0046] The low-refractive-index corrosion-resistant glass material prepared by the method in this embodiment has a refractive index of 1.46. After 15 cycles of etch tests, the difference in turbidity is less than 0.3, the transmittance is 90.1% (a decrease of 1.3%), the glass transition temperature Tg is 569℃, the expansion softening temperature Tf is 652℃, the softening point temperature Ts is 760℃, and the coefficient of thermal expansion is 81.9 × 10⁻⁶. -7 With a temperature of / ℃, it has good processability and adaptability, and can be used as a glass material for the fabrication of optical fiber image converters. The resulting optical fiber image converter also has good corrosion resistance, which can fundamentally meet the requirements of extreme environment applications.

[0047] Example 4 The low-refractive-index corrosion-resistant glass material of this embodiment is composed of the following batch components by mass percentage: 44.2% SiO2, 13.9% Al(OH)3, 1.1% MgCO3, 3.5% Na2CO3, 1.3% CaCO3, 23.1% KNO3, 11% H3BO3, 0.6% CeO2, and 1.3% YF3.

[0048] The method for preparing the low-refractive-index corrosion-resistant glass material in this embodiment is as follows: after mixing the various glass raw materials in proportion, the batch is melted at a high temperature of 1455℃, clarified by auxiliary stirring, mechanically drawn at 1205℃, and annealed at 570℃ to obtain the final product.

[0049] The low-refractive-index corrosion-resistant glass material prepared by the method in this embodiment has a refractive index of 1.47. After 15 cycles of etch tests, the turbidity difference is less than 0.3, the transmittance is 90.3% (a decrease of 1.1%), the glass transition temperature Tg is 573℃, the expansion softening temperature Tf is 655℃, the softening point temperature Ts is 770℃, and the coefficient of thermal expansion is 84.3 × 10⁻⁶. -7 With a temperature of / ℃, it has good processability and adaptability, and can be used as a glass material for the fabrication of optical fiber image converters. The resulting optical fiber image converter also has good corrosion resistance, which can fundamentally meet the requirements of extreme environment applications.

[0050] Example 5 The low-refractive-index corrosion-resistant glass material of this embodiment is composed of the following batch components by mass percentage: 62.9% SiO2, 12.1% Al(OH)3, 1.5% MgCO3, 2.7% Na2CO3, 0.0% CaCO3, 14.1% KNO3, 5.7% H3BO3, 0.9% CeO2, and 0.1% YF3.

[0051] The method for preparing the low-refractive-index corrosion-resistant glass material in this embodiment is as follows: after mixing the various glass raw materials in proportion, the batch is melted at a high temperature of 1530°C, clarified by auxiliary stirring, mechanically drawn at 1295°C, and annealed at 558°C to obtain the final product.

[0052] The low-refractive-index corrosion-resistant glass material prepared by the method in this embodiment has a refractive index of 1.46. After 15 cycles of etch testing, the turbidity difference is less than 0.3, the transmittance is 90.5% (a decrease of 0.9%), the glass transition temperature Tg is 572℃, the expansion softening temperature Tf is 646℃, the softening point temperature Ts is 758℃, and the coefficient of thermal expansion is 80.6 × 10⁻⁶. -7 With a temperature of / ℃, it has good processability and adaptability, and can be used as a glass material for the fabrication of optical fiber image converters. The resulting optical fiber image converter also has good corrosion resistance, which can fundamentally meet the requirements of extreme environment applications.

[0053] Example 6 The low-refractive-index corrosion-resistant glass material of this embodiment is composed of the following batch components by mass percentage: 48.6% SiO2, 16.2% Al(OH)3, 0.9% MgCO3, 3.9% Na2CO3, 1.7% CaCO3, 19.6% KNO3, 8.3% H3BO3, 0.4% CeO2, and 0.4% YF3.

[0054] The method for preparing the low-refractive-index corrosion-resistant glass material in this embodiment is as follows: after mixing the various glass raw materials in proportion, the batch is melted at a high temperature of 1485℃, clarified by auxiliary stirring, mechanically drawn at 1215℃, and annealed at 545℃ to obtain the final product.

[0055] The low-refractive-index corrosion-resistant glass material prepared by the method in this embodiment has a refractive index of 1.47. After 15 cycles of etch tests, the difference in turbidity is less than 0.3, the transmittance is 90.1% (a decrease of 1.3%), the glass transition temperature Tg is 554℃, the expansion softening temperature Tf is 660℃, the softening point temperature Ts is 768℃, and the coefficient of thermal expansion is 85.1×10⁻⁶. -7 With a temperature of / ℃, it has good processability and adaptability, and can be used as a glass material for the fabrication of optical fiber image converters. The resulting optical fiber image converter also has good corrosion resistance, which can fundamentally meet the requirements of extreme environment applications.

[0056] Comparative Example 1 The glass material of this comparative example is composed of the following mass percentages of batch material: 60.1% SiO2, 5.2% Al(OH)3, 0.5% MgCO3, 6.5% Na2CO3, 2.0% CaCO3, 19.1% KNO3, 6.5% H3BO3, and 0.1% YF3.

[0057] The glass material preparation method of this comparative example is as follows: after mixing the various glass raw materials in proportion, it is prepared according to the method of Example 1.

[0058] The testing method is the same as in Example 1. The refractive index of the glass material in this comparative example is 1.55. After 15 cycles of etch tests, the turbidity difference was ≥0.3 and <1.0, the transmittance was 85.1% (a decrease of 6.3%), the glass transition temperature Tg was 578℃, the softening temperature Tf was 650℃, the softening point temperature Ts was 773℃, and the coefficient of thermal expansion was 83.2 × 10⁻⁶. -7 / ℃.

[0059] Comparative Example 2 The glass material of this comparative example is composed of the following mass percentages of batch material: 60.1% SiO2, 5.2% Al(OH)3, 0.5% MgCO3, 6.5% Na2CO3, 2.0% CaCO3, 19.1% KNO3, 6.5% H3BO3, and 0.1% CeO2.

[0060] The glass material preparation method of this comparative example is as follows: after mixing the various glass raw materials in proportion, it is prepared according to the method of Example 1.

[0061] The testing method is the same as in Example 1. The refractive index of the glass material in this comparative example is 1.56. After 15 cycles of etch tests, the turbidity difference was ≥0.3 and <1.0, the transmittance was 87.2% (a decrease of 4.2%), the glass transition temperature Tg was 563℃, the softening temperature Tf was 655℃, the softening point temperature Ts was 767℃, and the coefficient of thermal expansion was 91.2 × 10⁻⁶. -7 / ℃.

[0062] Comparative Example 3 The glass material of this comparative example is composed of the following mass percentages of batch material: 60.0% SiO2, 5.2% Al2O3, 0.5% MgCO3, 6.5% Na2CO3, 2.0% CaCO3, 19.1% KNO3, 6.5% H3BO3, 0.1% CeO2, and 0.1% YF3.

[0063] The glass material preparation method of this comparative example is as follows: after mixing the various glass raw materials in proportion, it is prepared according to the method of Example 1.

[0064] The testing method is the same as in Example 1. The refractive index of this comparative glass material is 1.52. After 15 cycles of etch tests, the turbidity difference was ≥0.3 and <1.0, the transmittance was 87.5% (a decrease of 3.9%), the glass transition temperature Tg was 567℃, the softening temperature Tf was 660℃, the softening point temperature Ts was 760℃, and the coefficient of thermal expansion was 84.4 × 10⁻⁶. -7 / ℃.

[0065] Comparative Example 4 The glass material of this comparative example is composed of the following mass percentages of batch material: 60.0% SiO2, 5.2% Al(OH)3, 0.5% Mg(NO3)2, 6.5% Na2CO3, 2.0% Ca(NO3)2, 19.1% KNO3, 6.5% H3BO3, 0.1% CeO2, and 0.1% YF3.

[0066] The glass material preparation method of this comparative example is as follows: after mixing the various glass raw materials in proportion, it is prepared according to the method of Example 1.

[0067] The testing method is the same as in Example 1. The refractive index of this comparative glass material is 1.49. After 15 cycles of etch tests, the turbidity difference was ≥0.3 and <1.0, the transmittance was 87.4% (a decrease of 4.0%), the glass transition temperature Tg was 554℃, the softening temperature Tf was 658℃, the softening point temperature Ts was 762℃, and the coefficient of thermal expansion was 90.4 × 10⁻⁶. -7 / ℃.

[0068] Comparative Example 5 The glass material of this comparative example is composed of the following mass percentages of batch material: 60.0% SiO2, 5.2% Al(OH)3, 0.5% MgCO3, 6.5% NaNO3, 2.0% CaCO3, 19.1% K2CO3, 6.5% H3BO3, 0.1% CeO2, and 0.1% YF3.

[0069] The glass material preparation method of this comparative example is as follows: after mixing the various glass raw materials in proportion, it is prepared according to the method of Example 1.

[0070] The testing method is the same as in Example 1. The refractive index of this comparative glass material is 1.52. After 15 cycles of etch tests, the turbidity difference was ≥0.3 and <1.0, the transmittance was 87.9% (a decrease of 3.5%), the glass transition temperature Tg was 558℃, the softening temperature Tf was 648℃, the softening point temperature Ts was 765℃, and the coefficient of thermal expansion was 81.2 × 10⁻⁶. -7 / ℃.

[0071] Comparative Example 6 The glass material of this comparative example is composed of the following mass percentages of batch material: 57.0% SiO2, 5.2% Al(OH)3, 0.5% MgCO3, 6.5% Na2CO3, 2.0% CaCO3, 22.1% KNO3, 6.5% H3BO3, 0.1% CeO2, and 0.1% YF3.

[0072] The glass material preparation method of this comparative example is as follows: after mixing the various glass raw materials in proportion, it is prepared according to the method of Example 1.

[0073] The testing method is the same as in Example 1. The refractive index of the glass material in this comparative example is 1.51. After 15 cycles of etch tests, the turbidity difference was ≥0.3 and <1.0, the transmittance was 88% (a decrease of 3.4%), the glass transition temperature Tg was 556.5℃, the softening temperature Tf was 657℃, the softening point temperature Ts was 755.5℃, and the coefficient of thermal expansion was 79.4 × 10⁻⁶. -7 / ℃.

[0074] Using the glass material described in the above embodiment as the cladding glass material, it is drawn together with commonly used core materials to prepare an optical fiber image converter. After single-filament and multiple multifilament drawing, the multifilaments are regularly arranged and then melted and pressed into a blank plate segment. Then, after slicing, rolling, grinding and polishing, an erosion-resistant optical fiber image converter is prepared. The transmittance at a wavelength of 560nm is tested to show a decrease of no more than 1.4% before and after 15 cycles of erosion test.

[0075] Tables 1 and 2 below summarize the glass sample composition and glass properties of the above-described illustrative embodiments and comparative examples of the present invention.

[0076] Table 1. Composition of glass samples from Examples 1-6 and Comparative Examples 1-6

[0077] Table 2. Performance test results of glass samples from Examples 1-6 and Comparative Examples 1-6

[0078] As shown in Table 2, the low-refractive-index, corrosion-resistant glass provided by this invention has a refractive index ≤1.48, a glass transition temperature Tg ≤580℃, an expansion softening temperature Tf ≤670℃, and a softening point temperature Ts ≤775℃. It exhibits good processability and adaptability, and its coefficient of thermal expansion in the range of 20℃ to 300℃ is (80~87)×10⁻⁶. -7 With a temperature of / ℃, it has good thermal processing performance, which is conducive to the molding and preparation of large-size devices. It is compatible with core glass materials and can be used to manufacture optical glass fibers and fiber optic image converters. After 15 cycles of erosion experiments, the glass turbidity difference is less than 0.3. The fiber optic image converter prepared also has good erosion resistance and high strength, which can fundamentally meet the requirements of extreme environment applications.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A low-refractive-index, corrosion-resistant glass, characterized in that, Based on the mass percentage content of the batching powder, it is composed of the following raw materials: 44-65% SiO2, 5-16.5% Al(OH)3, 2-7% Na2CO3, 14-26.5% KNO3, 5-13% H3BO3, 0.5-5% alkaline earth metal carbonates, 0.1-1% CeO2, and 0.1-1.5% YF3, wherein the alkaline earth metal carbonates are selected from at least one of CaCO3 and MgCO3, and the total amount of silica, boric acid, and aluminum hydroxide introduced ranges from 69-81%.

2. The low-refractive-index, corrosion-resistant glass as described in claim 1, characterized in that, The mass content of SiO2 is 42~65%, 44~60%, 45~60%, 50~60%, 55~60%, 60~65%, 60~63%, 55~63%, 50~56%, 49.5~60%, 57.8~61.7%, 60.0~64.8%, 44.7~52.7%, 46.8~52.7%, or 56.8~60.7%; Alternatively, the boric acid content may be 5-6.5%, 5-6.9%, 5-7.3%, 5.2-8.2%, 6.9-8%, 6.9-8.2%, 6.2-9.9%, 7.2-16%, 7.2-11%, 7.2-10%, 5.2-6.7%, 6.1-6.9%, 6.5-7.9%, 7.2-8%, 5.8-7.2%, 6.9-7.2%, or 7.2-7.8% by mass. Alternatively, the mass content of aluminum hydroxide is 5~5.4%, 5~5.7%, 5~6.3%, 5~7%, 5~7.9%, 6~7.9%, 7.9~10%, 7.1~9.1%, 7.1~10.9%, 10.9~14%, 14.9~15.1%, 15.1~16.5%, 5.1~7.1%, or 14.1~16.5%; Alternatively, the total mass content of silicon dioxide, boric acid, and aluminum hydroxide is 70-75%, 70-73%, 71-80%, or 75-80%.

3. The low-refractive-index, corrosion-resistant glass as described in claim 1, characterized in that, The mass content of CeO2 is 0.1~0.2%, 0.1~0.3%, 0.1~0.5%, 0.5~0.6%, 0.5~0.7%, 0.5~0.8%, 0.5~0.9%, or 0.3~0.7%.

4. The low-refractive-index, corrosion-resistant glass as described in claim 1, characterized in that, The total mass of sodium carbonate and potassium nitrate is ≤33% or 17~33%; Alternatively, the mass content of sodium carbonate is 2-5%, 2-4%, 2-3%, 2-6.5%, 2-6%, 2-5%, 3-6.5%, 4-6.5%, 5-6.5%, 6-6.5%, or 6.3-6.5%; Alternatively, the mass content of potassium nitrate is 14~28.3%, 14~26.3%, 14~25.5%, 14~24.9%, 14.9~26.5%, 14.9~19.6%, 14.9~19.3%, 15~19.6%, 15~19.3%, 16~28.3%, 16~19.6%, 16~19.3%, 16.3~19%, 16~19.3%, or 18~19.3%.

5. The low-refractive-index, corrosion-resistant glass as described in claim 1, characterized in that, The mass content of YF3 is 0.1~1.3%, 0.1~0.5%, 0.1~1.3%, 0.1~1.2%, 0.2~1.5%, 0.1~0.2%, 0.1~0.3%, 0.2~0.5%, 0.5~1.5%, 0.2~1.3%, 0.3~1.5%, 0.3~0.5%, and 0.5~1.2%.

6. The low-refractive-index resistant glass as described in claim 1, characterized in that Mg The mass content of CO3 is 0~2%, 0~0.5%, 0.1~0.5%, 0.2~0.5%, 0.5~1.5%, or 0.3~0.7%; Alternatively, the mass content of CaCO3 is 0~2%, 0~1%, 1~1.2%, 0.5~1%, or 1.7~2.0%. Alternatively, the mass content of alkaline earth metal carbonates is 1.5~2%, 2~5%, or 2.2~2.8%.

7. The low-refractive-index, corrosion-resistant glass as described in claim 1, characterized in that, The refractive index of the glass is ≤1.48 or ≤1.47; Alternatively, for Tg≤580℃, Tf≤670℃, and Ts≤775℃, the coefficient of thermal expansion in the range of 20℃~300℃ is (80~87)×10. -7 / ℃.

8. A method for preparing the low-refractive-index, erosion-resistant glass according to claim 1, comprising the following steps: Glass blanks are prepared by mixing raw materials in proportion, high-temperature melting of raw materials, stirring-assisted clarification and homogenization, drawing and shaping, and high-precision annealing.

9. The preparation method according to claim 8, characterized in that, The high-temperature melting temperature is 1350~1550℃, the drawing temperature is 1050~1350℃, and the annealing temperature is 500~600℃.

10. The application of the low-refractive-index, erosion-resistant glass according to any one of claims 1 to 7 in an optical fiber image inverter.

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