High-strength heat-resistant glass and preparation method thereof

Abstract

The invention relates to high-strength and heat-resistant glass and a preparation method thereof, and belongs to the technical field of glass manufacturing, and the high-strength and heat-resistant glass comprises the following chemical components: SiO2, B2O3, Na2O, K2O, Al2O3, MgO, CaO, ZnO, Li2O, P2O5, Nb2O5, Re2O7, Gd2O3 and SrO. The average linear thermal expansion coefficient of the high-strength and heat-resistant glass prepared by the invention is (2.94 to 3.23) * 10 <-7 > / DEG C, the softening temperature is 710.1 to 720.4 DEG C, the breaking strength is 206.4 to 214.5 MPa, the impact strength is 49 to 54 cm, and the microhardness is 570 to 608 MPa.

Description

Technical Field

[0001] The present invention relates to a high-strength and heat-resistant glass and a preparation method thereof, belonging to the technical field of glass manufacturing. Background Art

[0002] As an important amorphous inorganic non-metallic material, glass has characteristics such as high light transmittance, high strength, easy processing, good corrosion resistance and heat resistance, and is the main material for optical components, electronic display parts and building decoration supplies. With the continuous expansion of its application fields, various properties of glass materials also need to be improved urgently, especially the strength and heat resistance of glass, which are crucial for expanding application scenarios and extending service life. Therefore, developing high-strength and heat-resistant glass is one of the main research and development directions in the glass industry in the future.

[0003] Among many glass varieties, the strength and heat resistance of borosilicate glass are generally better than those of other varieties. Therefore, the focus of the industry on developing high-strength and heat-resistant glass is mostly concentrated on borosilicate glass. The glass composed of SiO2, B2O3, Al2O3, and Na2O as the basic components is called borosilicate glass. In borosilicate glass, the mass content of SiO2 is in the range of 70-82wt%, and the mass content of B2O3 is also as high as 6-15wt%. Such high contents of SiO2 and B2O3 endow borosilicate glass with a very complete glass phase network structure and extremely high network density, making borosilicate glass exhibit excellent properties such as high strength, hardness, high temperature resistance, and heat shock resistance. Therefore, the application scope of borosilicate glass involves instrument glass, cookware glass, building fireproof glass, display glass, chemical equipment window glass, optical glass, etc. Although borosilicate glass has some advantages that other glass varieties cannot match, it also has inherent problems such as high melting temperature, high viscosity at high temperature, difficult clarification, serious boron volatilization during the melting process, and easy phase separation of the glass. And with the continuous expansion of application fields, when borosilicate glass is used in fields such as fireproof glass, flat panel display, solar energy, and aerospace equipment, its strength and heat resistance are difficult to meet the increasingly stringent requirements. Especially when forming large-size flat glass by the float process, due to the above-mentioned inherent problems, there is currently no particularly perfect and mature technology to ensure the high strength and high heat resistance of large-size borosilicate flat glass. Therefore, it is a consensus in the glass industry at the technical level to improve from directions such as glass composition, structure, and melting process in order to solve the inherent problems in the manufacturing process of borosilicate glass and then obtain high-strength and heat-resistant large-size glass products.

[0004] Chinese Patent CN115925250A discloses a medium borosilicate glass with a high softening point, a strengthened glass, and their preparation methods and applications. In terms of mass percentage, the components of the medium borosilicate glass with a high softening point include: SiO2 60 - 72%, Al2O3 9 - 18%, B2O3 4 - 10%, Na2O 3 - 7%, K2O 0 - 1%, MgO 10 - 17%, CaO 0 - 2%, and ZrO2 0.05 - 2%. The medium borosilicate glass obtained by this invention has a low thermal expansion coefficient, a high softening point, high mechanical properties, and a simple preparation process. After strengthening, the surface stress is 300MPa - 700MPa, the stress layer depth is greater than 10μm, and the thermal radiation anti-softening time is durable. The high strength and surface hardness of the medium borosilicate glass prepared by this patent are based on the surface strengthening, and the mechanical properties of the glass body have not been substantially enhanced. Moreover, the depth of the stress strengthening layer is limited, and for application fields with a larger glass thickness, the requirement of overall high strength performance cannot be achieved.

[0005] Chinese Patent CN105712623A discloses a borosilicate glass with low brittleness and high intrinsic strength, and its manufacturing and applications. This patent details the main component oxides in terms of the specific chemical composition of borosilicate, and defines and systematically gives the precise ratio of these component oxides from the height of theoretical formulas to obtain a high-strength and low-brittle borosilicate glass. However, this patent does not effectively solve the problems of high viscosity, boron volatilization, and easy phase separation in the actual manufacturing process of borosilicate glass. Moreover, in the preferred weight percentage composition range of the glass defined in this patent, SiO2 is above 71%, most are above 75%, and B2O3 is above 11%, most are 14% and above. This undoubtedly increases the difficulty of glass melting because the higher the SiO2 content, the greater the viscosity of the glass melt, and the higher the B2O3 content, the more serious the boron volatilization problem.

[0006] As can be seen from the above, the preparation of high-strength and heat-resistant borosilicate glass still cannot essentially improve its high-strength and heat-resistant properties from the perspectives of glass body composition and melting process. Therefore, it is a very meaningful method and approach to improve from the glass structure, composition, and glass melting process in order to overcome problems such as high melting temperature, high viscosity, difficult clarification, boron volatilization, and easy phase separation during the melting process of borosilicate glass. Summary of the Invention

[0007] Aiming at the deficiencies of the above-mentioned existing technologies, the present invention provides a high-strength and heat-resistant glass and its preparation method, achieving the following invention objectives: overcoming problems such as high melting temperature, high viscosity, difficult clarification, boron volatilization, and easy phase separation during the melting process of borosilicate glass by regulating glass structure, raw material composition, and melting process, and then preparing a high-strength and heat-resistant borosilicate glass.

[0008] To achieve the above-mentioned invention object, the present invention adopts the following technical solutions: A high-strength and heat-resistant glass and a preparation method thereof. The chemical composition of the high-strength and heat-resistant glass is as follows, by mass fraction: 70-84wt% SiO2, 10-20wt% B2O3, 2-8wt% Na2O, 2-8wt% K2O, 0-6wt% Al2O3, 0-3wt% MgO, 0-2wt% CaO, 0-1wt% ZnO, 0-1wt% Li2O, 0.1-0.6wt% P2O5, 0.1-0.6wt% Nb2O5, 0.08-0.25wt% Re2O7, 0-0.1wt% Gd2O3, 0-0.08wt% SrO; The raw materials of the high-strength and heat-resistant glass include silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifying agent; The borate is one of aluminum borate, zinc borate, magnesium borate, calcium borate, lithium borate, potassium borate, sodium borate, any two of them, or a mixture of any two or more of them; The flux is a mixture of niobate and phosphate; The niobate is one of lithium niobate, potassium niobate, strontium niobate, a mixture of any two of them in any mass ratio, or a mixture of any two or more of them in any mass ratio; The phosphate is one of magnesium phosphate, aluminum phosphate, calcium phosphate, lithium phosphate, a mixture of any two of them in any mass ratio, or a mixture of any two or more of them in any mass ratio; The mass ratio of the niobate to the phosphate is 3-13:40; The clarifying agent is one of potassium perrhenate, sodium perrhenate, gadolinium perrhenate, a mixture of any two of them in any mass ratio, or a mixture of any two or more of them in any mass ratio; The following is a further improvement of the above technical solution:

[0009] Step 1, melting According to the chemical composition of the high-strength and heat-resistant glass by mass fraction, weigh the corresponding masses of silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifying agent. First, add potassium silicate, sodium silicate, and borate into the glass melting furnace, heat up at the first heating rate and keep it at a constant temperature until the first melting temperature. Then, add boron trioxide in batches with a fixed time interval between batches. The mass of each batch is the total mass of boron trioxide divided by the total number of batches. After the addition of boron trioxide is completed, heat up at the second heating rate and keep it at a constant temperature until the second melting temperature. Then, add silicon dioxide, flux, and clarifying agent, and keep it at a constant temperature for melting at the second melting temperature. After the melting is completed, a glass melt is obtained; Heat up at the first heating rate and keep the temperature constant at the first melting temperature, where the first heating rate is 3 - 6 °C / min and the first melting temperature is 1000 - 1200 °C; In the way of batches with a fixed time interval between batches, the total number of batches is 3 - 6 batches, and the fixed time is 10 - 20 minutes; Heat up at the second heating rate and keep the temperature constant at the second melting temperature, where the second heating rate is 1 - 4 °C / min and the second melting temperature is 1550 - 1680 °C; For the isothermal smelting, the smelting time is 60 - 100 minutes.

[0010] Step 2, Shaping Preheat the graphite mold to the constant temperature in advance, then quickly pour the glass melt into the graphite mold, maintain the annealing temperature, after the isothermal annealing is completed, cool it to room temperature, and then demold and polish to obtain high-strength and heat-resistant glass; The constant temperature is 700 - 900 °C; The annealing temperature is 750 - 850 °C; For the isothermal annealing, the isothermal time is 1 - 3.5 hours; When cooling to room temperature, the cooling rate is 1 - 4 °C / min.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. To solve the problem of high viscosity of borosilicate glass melt, the present invention designs a flux composed of niobate and phosphate. The melting points of the above two salts are relatively low and the fluidity is good after melting, which plays a very significant role in reducing the viscosity of the glass melt. While the viscosity of the glass melt decreases, the clarification effect of the glass melt will also become better accordingly. In addition, through the niobate, Nb2O5 is introduced into the final glass body. Niobium elements have a very positive and positive effect on improving the heat resistance and mechanical strength of borosilicate glass. Therefore, it can be seen that the flux composed of niobate and phosphate plays a very significant comprehensive improvement role in reducing the viscosity of the glass melt, the clarification efficiency of the glass melt, and the properties of the glass; 2. The clarifying agent composed of potassium perrhenate, sodium perrhenate, and gadolinium perrhenate added in the present invention mainly relies on the reaction process of the strong decomposition of perrhenate at high temperature to generate oxides to achieve the clarification of the high-viscosity borosilicate glass melt. Moreover, the generated Re2O7 has a very high melting point and can enter the borosilicate glass network to form a solid solution to improve the heat resistance of the borosilicate glass; 3. During the melting process of the borosilicate glass of the present invention, in order to minimize boron volatilization as much as possible to ensure that the boron content in the final glass product meets the initial design requirements, the conventional one-time feeding method is changed to a method of adding boron trioxide in multiple batches. Moreover, in order to promote the rapid melting of boron trioxide into a liquid and quickly enter the viscous glass melt in a liquid form to achieve the purpose of maximizing the inhibition of boron volatilization, the present invention first melts potassium silicate and sodium silicate with lower melting points into a liquid glassy substance, and at the same time adds borate with a higher melting point. After the borate melts, borate ions and silicate ions will initially form a borosilicate glass network. In this way, the subsequently added boron trioxide, after rapid melting, has better compatibility with the initially formed borosilicate glass network. Therefore, the liquid boron trioxide will be better melted and dispersed into the interior of the borosilicate glass network, thereby minimizing boron volatilization to the greatest extent. And the present invention limits the melting temperature of potassium silicate, sodium silicate, and borate to above 1000°C, mainly because the temperature range of boron volatilization is mainly in the low-temperature section below 1000°C. Adding boron trioxide in small batches and then quickly heating to above 1000°C also has a significant effect on inhibiting the amount of boron volatilization; 4. The high-strength and heat-resistant glass prepared by the present invention has an average linear thermal expansion coefficient of (2.94~3.23)×10 -7 / °C, a softening temperature of 710.1~720.4°C, a flexural strength of 206.4~214.5 MPa, an impact strength of 49~54 cm, and a microhardness of 570~608 MPa. Specific Embodiments

[0012] The following describes the preferred embodiments of the present invention. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0013] Example 1: A method for preparing high-strength and heat-resistant glass Step 1. Melting The chemical composition of the high-strength and heat-resistant glass is, by mass fraction: 76.33 wt% SiO2, 12 wt% B2O3, 3 wt% Na2O, 4 wt% K2O, 1 wt% Al2O3, 1 wt% MgO, 1 wt% CaO, 0.5 wt% ZnO, 0.5 wt% Li2O, 0.2 wt% P2O5, 0.3 wt% Nb2O5, 0.1 wt% Re2O7, 0.03 wt% Gd2O3, 0.04 wt% SrO; According to the chemical composition of high-strength and heat-resistant glass in terms of mass fraction, weigh the corresponding masses of silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifying agent. First, add potassium silicate, sodium silicate, and borate to the glass melting furnace, heat it at the first heating rate and keep it at a constant temperature until the first melting temperature. Then, add boron trioxide in batches with a fixed time interval between batches. The mass added in each batch is the total mass of boron trioxide divided by the total number of batches. After the addition of boron trioxide is completed, heat it at the second heating rate and keep it at a constant temperature until the second melting temperature. Then, add silicon dioxide, flux, and clarifying agent, and keep it at a constant temperature for melting at the second melting temperature. After the melting is completed, a glass melt is obtained; The borate is a mixture of aluminum borate, zinc borate, magnesium borate, calcium borate, lithium borate, potassium borate, and sodium borate; The flux is a mixture of niobate and phosphate; The niobate is a mixture of lithium niobate, potassium niobate, and strontium niobate; The phosphate is a mixture of magnesium phosphate, aluminum phosphate, calcium phosphate, and lithium phosphate; The mass ratio of the niobate to the phosphate is 9:40; The clarifying agent is a mixture of potassium perrhenate, sodium perrhenate, and gadolinium perrhenate; When heating at the first heating rate and keeping it at a constant temperature until the first melting temperature, the first heating rate is 4 °C / min, and the first melting temperature is 1100 °C; When adding in batches with a fixed time interval between batches, the total number of batches is 5 batches, and the fixed time is 13 minutes; When heating at the second heating rate and keeping it at a constant temperature until the second melting temperature, the second heating rate is 2 °C / min, and the second melting temperature is 1600 °C; For the constant-temperature melting, the melting time is 70 minutes.

[0014] Step 2: Forming Preheat the graphite mold to the constant temperature in advance, then quickly pour the glass melt into the graphite mold, maintain the annealing temperature, and after the constant-temperature annealing is completed, cool it to room temperature, and then demold and polish to obtain high-strength and heat-resistant glass; The constant temperature is 800 °C; The annealing temperature is 770 °C; For the constant-temperature annealing, the constant-temperature time is 2 hours; When cooling to room temperature, the cooling rate is 3 °C / min.

[0015] Example 2: A method for preparing high-strength and heat-resistant glass The chemical composition of the high-strength and heat-resistant glass is as follows, by mass fraction: 70 wt% SiO2, 20 wt% B2O3, 2 wt% Na2O, 6.72 wt% K2O, 1 wt% Li2O, 0.1 wt% P2O5, 0.1 wt% Nb2O5, 0.08 wt% Re2O7; According to the chemical composition of the high-strength and heat-resistant glass by mass fraction, weigh the corresponding masses of silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifying agent. First, add potassium silicate, sodium silicate, and borate to the glass melting furnace, heat at a first heating rate and hold at a first melting temperature. Then, add boron trioxide in batches with a fixed time interval between batches. The mass added in each batch is the total mass of boron trioxide divided by the total number of batches. After the addition of boron trioxide is complete, heat at a second heating rate and hold at a second melting temperature. Then, add silicon dioxide, flux, and clarifying agent, and hold for melting at the second melting temperature. After the melting is complete, a glass melt is obtained; The borate is potassium borate; The flux is a mixture of niobate and phosphate; The niobate is lithium niobate; The phosphate is lithium phosphate; The mass ratio of the niobate to the phosphate is 3:40; The clarifying agent is potassium perrhenate; When heating at the first heating rate and holding at the first melting temperature, the first heating rate is 3 °C / min, and the first melting temperature is 1000 °C; When adding in batches with a fixed time interval between batches, the total number of batches is 3 batches, and the fixed time is 10 minutes; When heating at the second heating rate and holding at the second melting temperature, the second heating rate is 1 °C / min, and the second melting temperature is 1550 °C; For the holding for melting, the melting time is 60 minutes.

[0016] Step 2: Shaping Preheat the graphite mold to the constant temperature in advance, then quickly pour the glass melt into the graphite mold, maintain the annealing temperature. After the constant-temperature annealing is completed, cool to room temperature, and then demold and polish to obtain the high-strength and heat-resistant glass; The constant temperature is 700 °C; The annealing temperature is 750 °C; For the constant-temperature annealing, the constant-temperature time is 1 hour; When cooling to room temperature, the cooling rate is 1 °C / min.

[0017] Example 3: A method for preparing a high-strength and heat-resistant glass The chemical composition of the high-strength and heat-resistant glass is as follows, by mass fraction: 84 wt% SiO2, 10 wt% B2O3, 2 wt% Na2O, 2 wt% K2O, 0.37 wt% Li2O, 0.6 wt% P2O5, 0.6 wt% Nb2O5, 0.25 wt% Re2O7, 0.1 wt% Gd2O3, 0.08 wt% SrO; According to the chemical composition of the high-strength and heat-resistant glass by mass fraction, weigh the corresponding masses of silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifying agent. First, add potassium silicate, sodium silicate, and borate to the glass melting furnace, heat at a first heating rate and hold at a first melting temperature. Then, add boron trioxide in batches with a fixed time interval between batches. The mass added in each batch is the total mass of boron trioxide divided by the total number of batches. After the addition of boron trioxide is completed, heat at a second heating rate and hold at a second melting temperature. Then, add silicon dioxide, flux, and clarifying agent, and hold for melting at the second melting temperature. After the melting is completed, a glass melt is obtained; The raw materials of the high-strength and heat-resistant glass include silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifying agent; The borate is lithium borate; The flux is a mixture of niobate and phosphate; The niobate is a mixture of lithium niobate and strontium niobate; The phosphate is lithium phosphate; The mass ratio of the niobate to the phosphate is 13:40; The clarifying agent is a mixture of potassium perrhenate, sodium perrhenate, and gadolinium perrhenate; The heating at the first heating rate and holding at the first melting temperature, the first heating rate is 6 °C / min, and the first melting temperature is 1200 °C; The method of adding in batches with a fixed time interval between batches, the total number of batches is 6 batches, and the fixed time is 20 minutes; The heating at the second heating rate and holding at the second melting temperature, the second heating rate is 4 °C / min, and the second melting temperature is 1680 °C; The holding for melting, the melting time is 100 minutes.

[0018] Step 2, forming Preheat the graphite mold to the constant temperature in advance, then quickly pour the glass melt into the graphite mold, maintain the annealing temperature, after the constant-temperature annealing is completed, cool to room temperature, and then demold and polish to obtain the high-strength and heat-resistant glass; The constant temperature is 900 °C; The annealing temperature is 850 °C; For the isothermal annealing, the isothermal time is 3.5 hours; For the cooling to room temperature, the cooling rate is 4 °C / min.

[0019] Example 4: A method for preparing high-strength and heat-resistant glass Step 1, melting The chemical composition of the high-strength and heat-resistant glass is, by mass fraction: 70 wt% SiO2, 10 wt% B2O3, 2 wt% Na2O, 5.72 wt% K2O, 6 wt% Al2O3, 3 wt% MgO, 2 wt% CaO, 1 wt% ZnO, 0.1 wt% P2O5, 0.1 wt% Nb2O5, 0.08 wt% Re2O7; According to the chemical composition of the high-strength and heat-resistant glass by mass fraction, weigh the corresponding masses of silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifying agent. First, add potassium silicate, sodium silicate, and borate into the glass melting furnace, heat up at the first heating rate and isothermally maintain at the first melting temperature. Then, add boron trioxide in batches with a fixed time interval between batches. The mass added in each batch is the total mass of boron trioxide divided by the total number of batches. After the addition of boron trioxide is completed, heat up at the second heating rate and isothermally maintain at the second melting temperature. Then, add silicon dioxide, flux, and clarifying agent, and isothermally melt at the second melting temperature. After the melting is completed, a glass melt is obtained; The borate is a mixture of aluminum borate, zinc borate, magnesium borate, and calcium borate; The flux is a mixture of niobate and phosphate; The niobate is potassium niobate; The phosphate is a mixture of magnesium phosphate, aluminum phosphate, and calcium phosphate; The mass ratio of the niobate to the phosphate is 11:40; The clarifying agent is potassium perrhenate; For heating up at the first heating rate and isothermally maintaining at the first melting temperature, the first heating rate is 4 °C / min, and the first melting temperature is 1100 °C; For adding in batches with a fixed time interval between batches, the total number of batches is 5 batches, and the fixed time is 13 minutes; For heating up at the second heating rate and isothermally maintaining at the second melting temperature, the second heating rate is 2 °C / min, and the second melting temperature is 1600 °C; For the isothermal melting, the melting time is 70 minutes; The operation of Step 2 is the same as that in Example 1.

[0020] Example 5: A method for preparing high-strength and heat-resistant glass The chemical composition of the high-strength and heat-resistant glass is as follows, by mass fraction: 72.72 wt% SiO2, 10 wt% B2O3, 8 wt% Na2O, 8 wt% K2O, 1 wt% Li2O, 0.1 wt% P2O5, 0.1 wt% Nb2O5, 0.08 wt% Re2O7; According to the chemical composition of the high-strength and heat-resistant glass by mass fraction, weigh the corresponding masses of silica, boron trioxide, potassium silicate, sodium silicate, borate, flux, and fining agent. First, add potassium silicate, sodium silicate, and borate to the glass melting furnace, heat at a first heating rate and hold at a first melting temperature. Then, add boron trioxide in batches with a fixed time interval between batches. The mass added in each batch is the total mass of boron trioxide divided by the total number of batches. After the addition of boron trioxide is completed, heat at a second heating rate and hold at a second melting temperature. Then, add silica, flux, and fining agent, and hold for melting at the second melting temperature. After the melting is completed, a glass melt is obtained; The borate is lithium borate; The flux is a mixture of niobate and phosphate; The niobate is lithium niobate; The phosphate is lithium phosphate; The mass ratio of the niobate to the phosphate is 9:40; The fining agent is potassium perrhenate; The heating at the first heating rate and holding at the first melting temperature, the first heating rate is 4 °C / min, and the first melting temperature is 1100 °C; The method of adding in batches with a fixed time interval between batches, the total number of batches is 5 batches, and the fixed time is 13 minutes; The heating at the second heating rate and holding at the second melting temperature, the second heating rate is 2 °C / min, and the second melting temperature is 1600 °C; The holding for melting, the melting time is 70 minutes; The operation of step 2 is the same as that of Example 1.

[0021] Comparative Example 1: Based on Example 1, in step 1, during melting, no borate is added, and the boron contained in the borate is replaced by the corresponding boron trioxide in an equal stoichiometric amount. The specific operation is as follows: Step 1, Melting Replace the boron contained in the borate with an equal amount of boron trioxide according to the stoichiometric coefficient, and replace the elements other than boron contained in the borate with an equal amount of silica of the corresponding mass. The specific replacement method is as follows: Convert the mass of the oxides corresponding to the non-oxygen elements other than boron contained in the borate into the mass of the corresponding oxides according to the stoichiometric coefficient, add up the masses of these oxides, and the obtained value is the mass of silica that should be added. Other operations are the same as in Example 1; The operation in Step 2 is the same as in Example 1.

[0022] Comparative Example 2: On the basis of Example 1, in Step 1, during melting, no flux is added, and all the oxides corresponding to the elements contained in the flux in the final glass composition are replaced with an equal amount of silica of the corresponding mass. The specific operation is as follows: Step 1, Melting Replace all the oxides corresponding to the elements contained in the flux in the final glass composition with an equal amount of silica of the corresponding mass. Other operations are the same as in Example 1; The operation in Step 2 is the same as in Example 1.

[0023] Comparative Example 3: On the basis of Example 1, in Step 1, during melting, replace the clarifying agent composed of a mixture of potassium perrhenate, sodium perrhenate, and gadolinium perrhenate with an equal mass of sodium fluorosilicate. The specific operation is as follows: Step 1, Melting Replace the clarifying agent composed of a mixture of potassium perrhenate, sodium perrhenate, and gadolinium perrhenate with an equal mass of sodium fluorosilicate. Other operations are the same as in Example 1; The operation in Step 2 is the same as in Example 1.

[0024] Comparative Example 4: On the basis of Example 1, in Step 1, during melting, change the feeding method of first adding potassium silicate, sodium silicate, and borate and then adding boron trioxide in batches to the conventional melting process of adding all raw materials at one time. The specific operation is as follows: Step 1, Melting The chemical composition of the high-strength and heat-resistant glass is, by mass fraction: 76.33 wt% SiO2, 12 wt% B2O3, 3 wt% Na2O, 4 wt% K2O, 1 wt% Al2O3, 1 wt% MgO, 1 wt% CaO, 0.5 wt% ZnO, 0.5 wt% Li2O, 0.2 wt% P2O5, 0.3 wt% Nb2O5, 0.1 wt% Re2O7, 0.03 wt% Gd2O3, 0.04 wt% SrO; According to the chemical composition of high-strength and heat-resistant glass in terms of mass fraction, weigh the corresponding masses of silica, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifying agent. Add all the above raw materials into the glass melting furnace at one time, heat up at the first heating rate and keep the temperature constant at the first melting temperature. After maintaining the same constant temperature time as in Example 1 at the first melting temperature, then heat up at the second heating rate and keep the temperature constant at the second melting temperature, and carry out constant temperature melting at the second melting temperature. After the melting is completed, a glass melt is obtained, and other operations are the same as in Example 1; The operation in Step 2 is the same as in Example 1.

[0025] Performance test: For the high-strength and heat-resistant glass obtained in Examples 1, 2, 3, 4, 5 and Comparative Examples 1, 2, 3, 4, test the following indexes: average linear thermal expansion coefficient, softening temperature, flexural strength, impact strength, microhardness, etc.: 1. Average linear thermal expansion coefficient: Test according to "GB / T 16920-2015 Determination of Average Linear Thermal Expansion Coefficient of Glass"; 2. Softening temperature: The softening temperature of the glass is measured by the wire drawing method, and the test instrument is a DNY type hanging wire method glass fixed-point viscosity tester; the length of the glass wire is 235 ± 1 mm, and the average diameter is 0.65 mm ± 0.10 mm. Hang it in the furnace of the test instrument and heat it up at a rate of 5 °C / min. The temperature when the glass wire elongates 1 mm per minute under its own gravity is defined as the softening temperature of the glass, which is usually also called the Littleton point, and the corresponding viscosity is about 10 6.6 Pa·S; 3. Flexural strength: Use a KJJ300-1 type electric flexure testing machine, maximum load: 300 N, accuracy: 1%, sample size: 50 mm × 4 mm × 2.5 mm, calculation formula: K = 3PL / 2BH 2 , where K is the flexural strength (MPa), P is the breaking load (N), L is the span (mm), B is the cross-sectional width (mm), H is the cross-sectional thickness (mm), and the flexural strength data is the average value of 10 sample tests; 4. Impact strength: Lift a 1040 g solid steel ball to a certain height and let it fall freely. The landing point is within the range of a 25 mm diameter centered on the sample center point. Pad the gap between the glass and the bracket with a rubber ring. If it does not break once, lift it to a certain height and continue to impact until the sample breaks. At this time, the height is the impact strength of the glass; 5. Microhardness: Cut the glass sample into a glass sheet with a thickness of 2.5 mm, clean it with clean water and then dry it, and make its surface smooth through grinding and polishing to facilitate observing the indentation length. Measure the hardness of the glass on a HVS-1000 digital display microhardness tester. Keep it on the sample surface for 15 s, and then observe the diagonal length of the indentation. Test at least 3 groups of indentation lengths and take the average value. The calculation formula for microhardness is: Hv = (1854 × P) / (9.81 × l 2 ), where Hv is the microhardness (MPa), P is the load (fixed at 0.1 kgf), and l is the average value of the diagonal length of the indentation (mm); The results are shown in Table 1 as follows: Table 1

[0026] It can be seen from the data in Table 1 that the average linear thermal expansion coefficients of Examples 1-5 are all below 3.3×10 -7 / °C, the softening temperature is as high as over 710°C, the flexural strength is greater than 200 MPa, the impact strength is about 50 cm, and the microhardness is above 570 MPa. This indicates that the borosilicate glass prepared by the present invention has excellent properties of high strength and heat resistance; in Comparative Example 1, borate is not added, that is, in the process of adding boron trioxide in batches, the initial low-temperature melt does not contain borate, only the melt of potassium silicate and sodium silicate. The test data of Comparative Example 1 show that the average linear thermal expansion coefficient of Comparative Example 1 rises to 6.05×10 -7 / °C, the softening temperature also drops to 601.9. It can be seen that without adding borosilicate, the heat resistance deteriorates sharply. This may be because the low-temperature melt composed of borate, potassium silicate, and sodium silicate has a particularly significant effect on reducing the boron volatilization during the hot melting process of boric anhydride, thereby ensuring that the boron content in the glass melt can meet the design requirements of the initial glass composition. The mechanical properties of Comparative Example 1 also decrease sharply, which also shows that the addition of borate helps to reduce boron volatilization, enabling a higher boron content to be obtained in the final glass body; in Comparative Example 2, no flux is added, and both the heat resistance and mechanical properties of Comparative Example 2 drop to the lowest values among Example 1 and all comparative examples. It can be seen that the flux composed of niobate and phosphate can effectively reduce the viscosity of the borosilicate glass melt, promote the formation and densification of the borosilicate glass network, and thus significantly improve the heat resistance and mechanical properties of the borosilicate glass; in Comparative Example 3, the clarifying agent composed of a mixture of potassium perrhenate, sodium perrhenate, and gadolinium perrhenate is replaced with an equal mass of sodium fluorosilicate. The heat resistance and mechanical properties of Comparative Example 3 are significantly lower than those of Example 1. It can be seen that the clarifying effect of the mixture of potassium perrhenate, sodium perrhenate, and gadolinium perrhenate is significantly better than that of sodium fluorosilicate. This may be because the perrhenate contained in potassium perrhenate, sodium perrhenate, and gadolinium perrhenate decomposes violently at high temperatures, which can strongly stir the bubbles in the high-viscosity borosilicate glass melt, thereby promoting the coalescence of tiny bubbles and accelerating the clarification efficiency of the glass melt. In addition, Re2O7 formed after the decomposition of perrhenate has very good compatibility with the glass network formed by the two elements of boron and silicon, which plays a relatively large role in the densification of the glass network to a certain extent, thereby promoting the improvement of various properties of the borosilicate glass; in Comparative Example 4, the feeding method of first adding potassium silicate, sodium silicate, and borate and then adding boric anhydride in batches is changed to the conventional melting process of adding all raw materials at once. The heat resistance and mechanical properties of Comparative Example 4 are much worse than those of Example 1. This shows that in the conventional melting process of adding materials at once, the problem of boron volatilization is difficult to avoid, which in turn affects the boron content in the final glass body network, resulting in a significant reduction in the mechanical properties and heat resistance of the borosilicate glass.

[0027] As described above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and all should be covered by the protection scope of the present invention.

Claims

1. A high-strength, heat-resistant glass, characterized in that: The chemical composition of the high-strength, heat-resistant glass is, by mass fraction: 70 - 84wt% SiO2, 10 - 20wt% B2O3, 2 - 8wt% Na2O, 2 - 8wt% K2O, 0 - 6wt% Al2O3, 0 - 3wt% MgO, 0 - 2wt% CaO, 0 - 1wt% ZnO, 0 - 1wt% Li2O, 0.1 - 0.6wt% P2O5, 0.1 - 0.6wt% Nb2O5, 0.08 - 0.25wt% Re2O7, 0 - 0.1wt% Gd2O3, 0 - 0.08wt% SrO; The raw materials of the high-strength, heat-resistant glass include silica, boric anhydride, potassium silicate, sodium silicate, borate, flux, and fining agent; The borate is one of aluminum borate, zinc borate, magnesium borate, calcium borate, lithium borate, potassium borate, sodium borate, any two of them, or a mixture of any two or more of them; The flux is a mixture of niobate and phosphate; The niobate is one of lithium niobate, potassium niobate, strontium niobate, a mixture of any two of them in any mass ratio, or a mixture of any two or more of them in any mass ratio; The phosphate is one of magnesium phosphate, aluminum phosphate, calcium phosphate, lithium phosphate, a mixture of any two of them in any mass ratio, or a mixture of any two or more of them in any mass ratio; The fining agent is one of potassium perrhenate, sodium perrhenate, gadolinium perrhenate, a mixture of any two of them in any mass ratio, or a mixture of any two or more of them in any mass ratio.

2. The high-strength, heat-resistant glass according to claim 1, characterized in that: The mass ratio of the niobate to the phosphate is 3 - 13:

40.

3. The preparation method of the high-strength, heat-resistant glass according to claim 1, characterized in that: The preparation method of the high-strength, heat-resistant glass includes two steps: melting and forming.

4. The preparation method of the high-strength, heat-resistant glass according to claim 3, characterized in that: For the melting, according to the chemical composition of the high-strength, heat-resistant glass by mass fraction, weigh the corresponding masses of silica, boric anhydride, potassium silicate, sodium silicate, borate, flux, and fining agent. First, add potassium silicate, sodium silicate, and borate into the glass melting furnace, heat at a first heating rate and keep it at a constant temperature until the first melting temperature. Then, add boric anhydride in batches with a fixed time interval between batches. The mass of each batch is the total mass of boric anhydride divided by the total number of batches. After the addition of boric anhydride is completed, heat at a second heating rate and keep it at a constant temperature until the second melting temperature. Then, add silica, flux, and fining agent, and keep it at a constant temperature for melting at the second melting temperature. After the melting is completed, a glass melt is obtained.

5. The preparation method of the high-strength, heat-resistant glass according to claim 4, characterized in that: Heating at the first heating rate and keeping it at a constant temperature until the first melting temperature, the first heating rate is 3 - 6°C / min, and the first melting temperature is 1000 - 1200°C; In the manner of batches with a fixed time interval between batches, the total number of batches is 3 to 6 batches, and the fixed time is 10 to 20 minutes; Heat up at the second heating rate and keep the temperature constant at the second melting temperature. The second heating rate is 1 to 4 °C / min, and the second melting temperature is 1550 to 1680 °C; For the constant temperature smelting, the smelting time is 60 to 100 minutes.

6. The method for preparing high-strength and heat-resistant glass according to claim 3, wherein: For the shaping, preheat the graphite mold to the constant temperature, then quickly pour the glass melt into the graphite mold, maintain the annealing temperature. After the constant temperature annealing is completed, cool it to room temperature, and then demold and polish to obtain high-strength and heat-resistant glass.

7. The method for preparing high-strength and heat-resistant glass according to claim 6, wherein: The constant temperature is 700 to 900 °C; The annealing temperature is 750 to 850 °C; For the constant temperature annealing, the constant temperature time is 1 to 3.5 hours; For cooling to room temperature, the cooling rate is 1 to 4 °C / min.

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