Window glass for aerospace and preparation method thereof

Abstract

The invention discloses window glass for aerospace and a preparation method thereof, and belongs to the field of glass, the window glass comprises the following raw materials by mass: 72 to 79% of SiO2, 10 to 15% of B2O3, 3 to 7% of Na2O, 0.5 to 2% of K2O, 1 to 2% of MgO, 0.5 to 2% of SrO, 0.05 to 0.3% of BaO, 0.5 to 2% of PbO, 0.05 to 0.5% of ZnO, 0.4 to 1% of ZrO2, 0.05 to 0.2% of TiO2, 0.1 to 0.4% of La2O3, and 1 to 2% of NaCl. The preparation method comprises the following steps: uniformly mixing the raw materials, melting, clarifying, forming to obtain a glass block, and annealing to obtain the glass. The material is suitable for the field of aerospace, not only has excellent thermal stability and mechanical properties, but also has certain radiation resistance, and has good adaptability and protection property to extreme environments in aerospace service.

Description

Technical Field

[0001] The invention belongs to the field of glass, and in particular, relates to a window glass for aerospace and a preparation method thereof. Background Art

[0002] With the continuous development of aerospace technology, the application areas of aerospace glass are also expanding. In addition to traditional fields such as spacecraft structural parts, observation windows, solar panels, etc., it is also used in laser weapon systems, space stations and other fields. Spacecraft will experience extreme temperature changes during flight. Aerospace glass must have a wide range of thermal stability and be able to maintain good light transmittance and mechanical strength under drastic temperature changes to ensure the normal operation of spacecraft under various temperature conditions. At the same time, there is high-energy radiation in the space environment, which is harmful to spacecraft and internal equipment and personnel. Aerospace glass must also have a certain radiation absorption capacity to effectively shield harmful radiation. Therefore, the application development of aerospace has also put forward more stringent requirements for aerospace glass.

[0003] In order to meet the above operating environment, aerospace glass must have excellent thermal stability, mechanical properties and optical protection properties, etc. Quartz glass is the most common aerospace material, but the preparation conditions of quartz glass are harsh, the production cost is high, the radiation protection ability is poor, and it is difficult to process into a hemispherical dome. These problems have largely limited the application of quartz glass. Summary of the invention

[0004] In order to overcome the above technical problems, the present invention provides a window glass for aerospace and a preparation method thereof. By adjusting the glass components, the glass has excellent thermal stability, chemical stability, mechanical properties and optical protection properties, providing key material support for major aerospace projects.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A window glass for aerospace includes the following raw materials in percentage by mass: SiO2: 72-79%, B2O3: 10-15%, Na2O: 3-7%, K2O: 0.5-2%, MgO: 1-2%, SrO: 0.5-2%, BaO: 0.05-0.3%, PbO: 0.5-2%, ZnO: 0.05-0.5%, ZrO2: 0.4%-1%, TiO2: 0.05-0.2%, La2O3: 0.1-0.4%, and NaCl: 1-2%.

[0007] Among them, the mass ratio of B2O3 / SiO2 is 0.12~0.19, the mass ratio of (Na2O+K2O) / B2O3 is 0.4~0.7, the mass ratio of K2O / Na2O is 0.15~0.3, the mass ratio of (MgO+SrO+BaO+PbO+ZnO) / (Na2O+K2O) is 0.7~1, and the mass ratio of ZnO / PbO is 0.1~0.3.

[0008] About the above components:

[0009] SiO2, as a glass network former, is the main component of the glass network skeleton, which can effectively reduce the thermal expansion coefficient of the glass and improve the thermal shock stability, heat resistance and mechanical strength of the glass. By regulating the content of SiO2 within the scope of this application, it is beneficial to the thermal stability and mechanical strength of the glass of this application. Therefore, the content of SiO2 is 72-79%, preferably 76-78%.

[0010] B2O3 has a very special role in glass and can be used as an oxide to form glass alone. It can improve various properties of glass and also has good fluxing properties, making it a good flux. When B2O3 is added to silicate glass, Na2O and K2O provide free oxygen to form boron-oxygen tetrahedrons [BO4] with boron. Since boron-oxygen tetrahedrons are frame structures, they can form uniform glass with silicon-oxygen tetrahedrons [SiO4] in the glass structure, thereby enhancing the network structure of the glass. However, when the amount of boron added exceeds a certain limit, it appears in the glass structure as boron-oxygen triangles instead of boron-oxygen tetrahedrons, causing the structure of boron to change from a frame structure to a layered structure, thereby reducing the degree of network connectivity of the glass. Therefore, by adjusting the content of B2O3, it is beneficial to reduce the viscosity of the glass liquid and improve the structural compactness of the glass, so that the glass of the present application has a good clarification effect and high mechanical strength. Therefore, the content of B2O3 is 10-15%, preferably 11-13%, the mass ratio of B2O3 / SiO2 is 0.12-0.19, and the mass ratio of (Na2O+K2O) / B2O3 is 0.4-0.7.

[0011] Na2O and K2O are the outer oxides of the glass network. + and K +Located in the holes of the glass structure network. Na2O and K2O can provide free oxygen to increase the O / Si ratio in the glass structure and cause bond breaking, thereby reducing the viscosity of the glass and making the glass easy to melt, and are glass fluxing agents. However, excessive Na2O and K2O content will reduce the chemical stability, thermal stability and mechanical strength of the glass. At the same time, the Na / K ratio will also affect the interconnectivity of the glass sub-network. The thermal expansion coefficient and thermal shock resistance of the aerospace window glass of the present invention are determined by the connectivity of the silicate sub-network. In order to better balance the above properties and obtain a glass material with better comprehensive performance, Na2O: 3-7%, K2O: 0.5-2%, preferably Na2O: 4-5%, K2O: 0.5-1%, and the mass ratio of K2O / Na2O is 0.15-0.3.

[0012] MgO, SrO, BaO, PbO and ZnO are all network oxides in glass. In the present invention, MgO is used instead of CaO to reduce the crystallization tendency, improve the glass forming performance, and improve the chemical stability and mechanical properties of the glass. The functions of SrO and BaO are the same as those of MgO, but the addition of SrO and BaO can improve the ability of glass to absorb radiation. The addition of PbO can significantly improve the radiation protection ability of glass, but the present invention must ensure the thermal stability and mechanical strength of the glass, so it can only be added in an appropriate amount. ZnO can reduce the thermal expansion coefficient of glass, improve the chemical stability and thermal stability of glass, especially when added to glass containing PbO, it helps to eliminate defects such as glass stripes. By adjusting the contents of MgO, SrO, BaO, PbO and ZnO within the scope of the present application, it is beneficial to improve the chemical stability and thermal stability of the glass and significantly improve the radiation protection ability of the glass, MgO: 1-2%, SrO: 0.5-2%, BaO 0.05-0.3%, PbO: 0.5-2%, ZnO: 0.05-0.5%, preferably MgO: 1.5-2%, SrO: 1-1.5%, BaO: 0.2-0.3%, PbO: 1-1.5%, ZnO: 0.1-0.3%, wherein the raw material of SrO is a mixture of SrCO3 and Sr(NO3)2, the mass ratio of SrCO3 / Sr(NO3)2 is 10-15, and the By adjusting the mass ratio of the mixture of SrCO3 and Sr(NO3)2, the problem of high viscosity of the glass melt and difficulty in clarification due to high SiO2 content can be improved; the mass ratio of (MgO+SrO+BaO+PbO+ZnO) / (Na2O+K2O) is 0.7~1. By adjusting the mass ratio of (MgO+SrO+BaO+PbO+ZnO) / (Na2O+K2O) in the glass within the scope of this application, it is beneficial to reduce the viscosity of the glass melt, which is beneficial to the melting of glass raw materials and the forming of glass blocks; the mass ratio of ZnO / PbO is 0.05~0.2. By adjusting the mass ratio of ZnO / PbO in the glass, it is helpful to eliminate defects such as stripes caused by the addition of PbO.

[0013] ZrO2 can significantly improve the chemical stability and thermal stability in glass, but the content should not be too high. Glass containing ZrO2 is easy to crystallize and difficult to melt. By adjusting the content of ZrO2 within the scope of this application, it is beneficial to reduce the thermal expansion coefficient and improve the thermal shock resistance of the glass of this application. Therefore, ZrO2: 0.4%~1%, preferably 0.5%~0.8%.

[0014] TiO2 can improve the refractive index and chemical stability of glass, and adding a proper amount can improve the ability of glass to shield radiation. However, glass containing TiO2 is prone to devitrification at low temperatures, so the content of TiO2 is adjusted within the scope of this application, TiO2: 0.05-0.2%, preferably TiO2: 0.08-0.1%.

[0015] La2O3 can effectively improve the chemical stability and radiation protection of glass. It also produces oxygen when thermally decomposed under high temperature conditions. Adding it together with NaCl helps clarify the glass. However, if its content is too high, it will also reduce the stability of the glass. Therefore, La2O3: 0.1-0.4%, preferably La2O3: 0.2-0.3%.

[0016] As a further solution of the present invention: the raw material of B2O3 is a mixture of B2O3 and H3BO3, and the mass ratio of B2O3 / H3BO3 is 10-12; the raw material of Na2O is a mixture of Na2CO3 and NaNO3, and the mass ratio of Na2CO3 / NaNO3 is 1-2.

[0017] As a further solution of the present invention: the raw material of SrO is a mixture of SrCO3 and Sr(NO3)2, and the mass ratio of SrCO3 / Sr(NO3)2 is 10-15.

[0018] The thermal expansion coefficient of the aerospace window glass obtained is 3.0×10 -6 / ℃~3.8×10 -6 / ℃, thermal shock resistance ΔT / ℃≥200, transmittance in the wavelength range of 450~780nm ≥90%, lead equivalent ≥0.15mmPb.

[0019] Another object of the present invention is to provide a method for preparing the aerospace window glass, which is as follows:

[0020] The raw materials are mixed uniformly, melted, clarified, and formed to obtain a glass block, which is then annealed to obtain the aerospace window glass.

[0021] In the above preparation method, the melting temperature is 1650℃~1700℃, the melting holding time is 2h~4h, the furnace working pressure during clarification is 0.3~0.7 standard atmospheric pressure, the clarification holding time is 0.5h~2h, and the annealing temperature is 700℃~800℃.

[0022] Beneficial effects of the present invention:

[0023] The invention is applicable to the field of aerospace, and the glass not only has excellent thermal stability and mechanical properties, but also has certain radiation protection, and has good adaptability and protection to the extreme environment in aerospace service.

[0024] The raw materials used in the present invention do not contain arsenic and antimony, and the provided preparation method has the advantages of simple preparation process, environmental friendliness, etc. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The present invention provides raw material components (mass percentage ratio) and performance indicators of the glasses of Examples 1 to 6 and Comparative Examples 1 to 5 as shown in Table 1:

[0027] The raw materials of SiO2, B2O3, Na2O, K2O, MgO, SrO, BaO, PbO, ZnO, ZrO2, TiO2, La2O3 and NaCl are SiO2, B2O3+H3BO3, Na2CO3+NaNO3, K2CO3, MgO, SrCO3+Sr(NO3)2, BaCO3, PbO·SiO2, ZnO, ZrO2, TiO2, La2O3 and NaCl respectively. The above raw materials are stirred and mixed evenly according to the proportions shown in Table 1, and then put into a melting furnace for high-temperature melting. The temperature in the high-temperature furnace body is raised to 1680°C and kept warm for 3 hours. The working gas pressure of the furnace during clarification is 0.5 standard atmospheric pressure, and the clarification holding time is 1 hour. After melting, it is poured into a mold for molding to obtain a glass block. The glass block is placed in an annealing furnace for annealing. The temperature of the annealing furnace is 750°C, and then the annealing furnace is closed. The glass block is naturally cooled to room temperature along with the annealing furnace. After annealing, it is cut, ground and polished to obtain aerospace window glass.

[0028] Table 1

[0029]

[0030]

[0031] From Examples 1 to 6 in Table 1, it can be seen that within the application component range, the thermal expansion coefficient of the aerospace window glass provided by the present invention is 3.0×10 -6 / ℃~3.8×10 -6 / ℃, thermal shock resistance ΔT / ℃≥200, transmittance in the wavelength range of 450-780nm ≥90%, lead equivalent ≥0.15mmPb, bubble degree grade A0. It can be seen that the aerospace window glass and preparation method provided by the present invention not only have excellent thermal shock resistance, but also have excellent radiation resistance.

[0032] From Table 1, it can be seen that the addition of components such as PbO and BaO in Example 1 can improve the radiation protection effect of glass. In Example 2, the over-range change of B2O3 / SiO2 reduces the network structure of glass, resulting in a decrease in the thermal stability of glass. In Example 3, the over-range change of Na2O leads to a decrease in the free oxygen provided in the glass, a decrease in boron oxygen tetrahedrons, and the appearance of boron oxygen triangles in the glass structure, which changes the structure of boron from a frame structure to a layered structure, reducing the degree of network connection of the glass. Therefore, the property is reversed. In Example 4, it can be seen that the reduction of NaCl will affect the clarification effect of the glass, resulting in an increase in the number of bubbles per unit. In Example 5, it can be seen that increasing the amount of PbO can greatly improve the radiation resistance of the glass, but the PbO content beyond the application range will cause changes in the structure and system of the glass, thereby changing the compactness of the glass network structure, and the thermal stability and optical properties of the glass are changed.

[0033] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A window glass for aerospace, characterized in that: The invention comprises the following raw materials in mass percentage: SiO2: 72-79%, B2O3: 10-15%, Na2O: 3-7%, K2O: 0.5-2%, MgO: 1-2%, SrO: 0.5-2%, BaO: 0.05-0.3%, PbO: 0.5-2%, ZnO: 0.05-0.5%, ZrO2: 0.4%-1%, TiO2: 0.05-0.2%, La2O3: 0.1-0.4%, NaCl: 1-2%; Among them, the mass ratio of B2O3 / SiO2 is 0.12~0.19, the mass ratio of (Na2O+K2O) / B2O3 is 0.4~0.7, the mass ratio of K2O / Na2O is 0.15~0.3, the mass ratio of (MgO+SrO+BaO+PbO+ZnO) / (Na2O+K2O) is 0.7~1, and the mass ratio of ZnO / PbO is 0.1~0.

3.

2. The aerospace window glass according to claim 1, characterized in that: The raw material of B2O3 is a mixture of B2O3 and H3BO3, and the mass ratio of B2O3 / H3BO3 is 10-12.

3. The aerospace window glass according to claim 1, characterized in that: The raw material of Na2O is a mixture of Na2CO3 and NaNO3, and the mass ratio of Na2CO3 / NaNO3 is 1-2.

4. The aerospace window glass according to claim 1, characterized in that: The raw material of SrO is a mixture of SrCO3 and Sr(NO3)2, and the mass ratio of SrCO3 / Sr(NO3)2 is 10-15.

5. The aerospace window glass according to claim 1, characterized in that: The thermal expansion coefficient of the aerospace window glass is 3.0×10 -6 / ℃~3.8×10 -6 / ℃, thermal shock resistance ΔT / ℃≥200, transmittance in the wavelength range of 450~780nm ≥90%, lead equivalent ≥0.15mmPb.

6. The method for preparing aerospace window glass according to any one of claims 1 to 5, characterized in that: The details are as follows: The raw materials are mixed uniformly, melted, clarified, and formed to obtain a glass block, which is then annealed to obtain the aerospace window glass.

7. The method for preparing window glass for aerospace use according to claim 6, characterized in that: The melting temperature is 1650°C to 1700°C, the melting holding time is 2h to 4h, the furnace working pressure during clarification is 0.3 to 0.7 standard atmospheric pressure, the clarification holding time is 0.5h to 2h, and the annealing temperature is 700°C to 800°C.

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