High-strength, heat-resistant glass and preparation method thereof

Abstract

A high-strength, heat-resistant glass and a preparation method thereof, belonging to the technical field of glass manufacturing, wherein the chemical composition of the high-strength, heat-resistant glass comprises SiO2, B2O3, Na2O, K2O, Al2O3, MgO, CaO, ZnO, Li2O, P2O5, Nb2O5, Re2O7, Gd2O3, and SrO; the high-strength, heat-resistant glass prepared by the present invention has an average linear thermal expansion coefficient of (2.94-3.23)×10 ‑7 / ℃, softening temperature is 710.1~720.4℃, flexural strength is 206.4~214.5MPa, impact strength is 49~54cm, and microhardness is 570~608MPa.

Description

Technical Field

[0001] The invention relates to high-strength 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 boasts high light transmittance, high strength, easy processing, and excellent corrosion and heat resistance. It is a primary material for optical components, electronic display parts, and architectural decoration. As its application continues to expand, the various properties of glass materials are in urgent need of improvement, especially glass strength and heat resistance, which are crucial for expanding applications and extending service life. Therefore, the development of high-strength, heat-resistant glass is a major research and development direction for the glass industry in the future.

[0003] Among many glass varieties, borosilicate glass generally boasts superior strength and heat resistance compared to other varieties. Consequently, the industry's focus on developing high-strength, heat-resistant glass has largely focused on borosilicate glass. Borosilicate glass is composed primarily of SiO2, B2O3, Al2O3, and Na2O. The SiO2 content in borosilicate glass ranges from 70% to 82% by weight, while the B2O3 content is as high as 6% to 15% by weight. These high SiO2 and B2O3 contents imbue borosilicate glass with a highly integrated glass phase network structure and exceptionally high network density, resulting in excellent properties such as high strength, hardness, high-temperature resistance, and thermal shock resistance. Consequently, borosilicate glass is widely used in applications such as instrument glass, cookware glass, architectural fireproof glass, display glass, chemical equipment window glass, and optical glass. Although borosilicate glass has some advantages that other glass types cannot match, it also has inherent problems such as high melting temperature, high viscosity at high temperature, difficulty in clarification, severe boron volatilization during the melting process, and easy phase separation of glass. In addition, with the continuous expansion of application fields, the strength and heat resistance of borosilicate glass when used in fire-resistant glass, flat panel displays, solar energy, aerospace equipment and other fields are difficult to meet the increasingly stringent requirements. In particular, when large-sized flat glass is formed using the float process, due to the inherent problems mentioned above, there is currently no particularly complete and mature technology to ensure the high strength and high heat resistance of large-sized borosilicate flat glass. Therefore, it is a unanimous consensus reached by the glass industry at the technical level to make improvements in the glass composition, structure, melting process, etc. in order to solve the inherent problems in the borosilicate glass manufacturing process and obtain high-strength, heat-resistant large-sized glass products.

[0004] Chinese patent CN115925250A discloses a medium-borosilicate glass with a high softening point, tempered glass, and its preparation method and application. The high-softening-point medium-borosilicate glass comprises, by mass percentage, 60-72% SiO2, 9-18% Al2O3, 4-10% B2O3, 3-7% Na2O, 0-1% K2O, 10-17% MgO, 0-2% CaO, and 0.05-2% ZrO2. The medium-borosilicate glass obtained by this invention exhibits a low thermal expansion coefficient, a high softening point, and excellent mechanical properties. The preparation process is simple, and after tempering, the glass exhibits a surface stress of 300-700 MPa, a stress layer depth greater than 10 μm, and a long-lasting resistance to thermal radiation softening. The high strength and surface hardness of the medium borosilicate glass prepared by this patent are obtained through surface strengthening. The mechanical properties of the glass itself are not substantially enhanced, and the depth of the stress-strengthening layer is limited. For applications where the glass thickness is relatively large, it cannot meet the requirements of overall high-strength performance.

[0005] Chinese patent CN105712623A discloses a borosilicate glass with low brittleness and high intrinsic strength, as well as its manufacture and application. The patent defines in detail the main constituent oxides based on the specific chemical composition of borosilicate, and defines and systematically gives the precise ratio of these constituent oxides from the perspective of theoretical formulas to obtain high-strength and low-brittle borosilicate glass. However, the patent does not effectively solve the difficult 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 by the patent, SiO2 is above 71%, and most are above 75%, while B2O3 is above 11%, and 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 will be.

[0006] From the above, it can be seen that the preparation of high-strength and heat-resistant borosilicate glass still has the problem of not being able to essentially improve its high strength and heat resistance from the perspective of the glass body composition and melting process. Therefore, improving the glass structure, composition, and glass melting process in order to overcome the problems of high melting temperature, high viscosity, difficulty in clarification, boron volatilization, and easy phase separation in the borosilicate glass melting process is a method and approach with great research significance and practical value. Summary of the Invention

[0007] In view of the deficiencies in the above-mentioned prior art, the present invention provides a high-strength, heat-resistant glass and a method for preparing the same, to achieve the following invention objectives: to overcome the problems of high melting temperature, high viscosity, difficulty in clarification, boron volatilization, and easy phase separation in the melting process of borosilicate glass by regulating the glass structure, raw material composition, and melting process, thereby preparing high-strength, heat-resistant borosilicate glass.

[0008] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0009] A high-strength, heat-resistant glass and a preparation method thereof. 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, and 0-0.08wt% SrO;

[0010] The raw materials of the high-strength, heat-resistant glass include silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifier;

[0011] The borate is one, any two or a mixture of any two or more of aluminum borate, zinc borate, magnesium borate, calcium borate, lithium borate, potassium borate and sodium borate;

[0012] The flux is a mixture of niobate and phosphate;

[0013] The niobate is one of lithium niobate, potassium niobate, and 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;

[0014] The phosphate is one of magnesium phosphate, aluminum phosphate, calcium phosphate, and 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;

[0015] The mass ratio of the niobate to the phosphate is 3 to 13:40;

[0016] The clarifier is one of potassium perrhenate, sodium perrhenate, and 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;

[0017] The following are further improvements to the above technical solution:

[0018] Step 1: Melting

[0019] According to the chemical composition of the high-strength and heat-resistant glass in terms of mass fraction, corresponding masses of silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifier are weighed; the potassium silicate, sodium silicate, and borate are first added to a glass melting furnace, the temperature is increased at a first heating rate and the temperature is kept constant to a first melting temperature; then, the boron trioxide is added in batches with a fixed interval between batches, the added mass of each batch being the total mass of the boron trioxide divided by the total number of batches; after the addition of the boron trioxide is completed, the temperature is increased at a second heating rate and the temperature is kept constant to a second melting temperature; then, silicon dioxide, flux, and clarifier are added, and the glass is melted at the second melting temperature; after the melting is completed, a glass melt is obtained;

[0020] The heating is carried out at a first heating rate and maintained at a constant temperature to a first melting temperature, wherein the first heating rate is 3-6°C / min and the first melting temperature is 1000-1200°C;

[0021] The method of batching with a fixed time interval between batches is as follows: the total number of batches is 3 to 6 batches, and the fixed time is 10 to 20 minutes;

[0022] The second heating rate is 1-4°C / min and the second melting temperature is 1550-1680°C.

[0023] The constant temperature smelting has a smelting time of 60 to 100 minutes.

[0024] Step 2: Molding

[0025] Preheat the graphite mold to a 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, then demould and polish it to obtain high-strength, heat-resistant glass;

[0026] The constant temperature is 700-900°C;

[0027] The annealing temperature is 750-850°C;

[0028] The constant temperature annealing time is 1 to 3.5 hours;

[0029] The temperature is lowered to room temperature at a rate of 1-4°C / min.

[0030] Compared with the prior art, the present invention achieves the following beneficial effects:

[0031] 1. To address the high viscosity of borosilicate glass melts, the present invention designs a flux composed of a mixture of niobate and phosphate. These two salts have low melting points and good fluidity after melting, significantly reducing the viscosity of the glass melt. As the viscosity of the glass melt decreases, the clarification effect of the glass melt is also correspondingly improved. Furthermore, niobate introduces Nb2O5 into the final glass. Niobium has a very positive effect on improving the heat resistance and mechanical strength of borosilicate glass. Therefore, it can be seen that the flux composed of a mixture of niobate and phosphate has a very significant comprehensive effect on reducing the viscosity of the glass melt, improving the efficiency of glass melt clarification, and improving the performance of the glass.

[0032] 2. The clarifier composed of potassium perrhenate, sodium perrhenate, and gadolinium perrhenate added in the present invention mainly relies on the reaction process of perrhenate ions strongly decomposing at high temperature to form oxides to achieve clarification of high-viscosity borosilicate glass melts. The generated Re2O7 has a very high melting point and can form a solid solution by entering the borosilicate glass network, thereby improving the heat resistance of the borosilicate glass.

[0033] 3. During the melting process of the borosilicate glass of the present invention, in order to minimize boron volatilization and 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 multiple-time feeding method of boron trioxide. In addition, in order to promote the rapid melting of boron trioxide into liquid and to allow it to enter the viscous glass melt in liquid form as soon as possible to achieve the purpose of maximally suppressing boron volatilization, the present invention first melts potassium silicate and sodium silicate with lower melting points into liquid glass-like substances, and simultaneously adds borate with higher melting point. After the borate is melted, borate and silicate will initially form borosilicate. Glass network, so that the subsequently added boron trioxide, after rapid melting, has good compatibility with the above-mentioned initially formed borosilicate glass network, so the liquid boron trioxide will be well melted and dispersed into the interior of the borosilicate glass network, thereby minimizing boron volatilization. In addition, 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 range below 1000°C. Boron trioxide is added in small batches and then the temperature is quickly raised to above 1000°C, which also has a relatively significant effect on suppressing the amount of boron volatilization.

[0034] 4. The high-strength, heat-resistant glass prepared by the present invention has an average linear thermal expansion coefficient of (2.94~3.23)×10 -7 / ℃, softening temperature is 710.1~720.4℃, flexural strength is 206.4~214.5MPa, impact strength is 49~54cm, and microhardness is 570~608MPa. DETAILED DESCRIPTION

[0035] The preferred embodiments of the present invention are described below. 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.

[0036] Example 1: A method for preparing high-strength, heat-resistant glass

[0037] Step 1: Melting

[0038] The chemical composition of the high-strength and heat-resistant glass is, by mass fraction: 76.33wt% SiO2, 12wt% B2O3, 3wt% Na2O, 4wt% K2O, 1wt% Al2O3, 1wt% MgO, 1wt% CaO, 0.5wt% ZnO, 0.5wt% Li2O, 0.2wt% P2O5, 0.3wt% Nb2O5, 0.1wt% Re2O7, 0.03wt% Gd2O3, 0.04wt% SrO;

[0039] According to the chemical composition of the high-strength and heat-resistant glass in terms of mass fraction, corresponding masses of silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifier are weighed; the potassium silicate, sodium silicate, and borate are first added to a glass melting furnace, the temperature is increased at a first heating rate and the temperature is kept constant to a first melting temperature; then, the boron trioxide is added in batches with a fixed interval between batches, the added mass of each batch being the total mass of the boron trioxide divided by the total number of batches; after the addition of the boron trioxide is completed, the temperature is increased at a second heating rate and the temperature is kept constant to a second melting temperature; then, silicon dioxide, flux, and clarifier are added, and the glass is melted at the second melting temperature; after the melting is completed, a glass melt is obtained;

[0040] The borate is a mixture of aluminum borate, zinc borate, magnesium borate, calcium borate, lithium borate, potassium borate and sodium borate;

[0041] The flux is a mixture of niobate and phosphate;

[0042] The niobate is a mixture of lithium niobate, potassium niobate and strontium niobate;

[0043] The phosphate is a mixture of magnesium phosphate, aluminum phosphate, calcium phosphate and lithium phosphate;

[0044] The mass ratio of the niobate to the phosphate is 9:40;

[0045] The clarifier is a mixture of potassium perrhenate, sodium perrhenate, and gadolinium perrhenate;

[0046] The heating is carried out at a first heating rate and maintained at a constant temperature to a first melting temperature, wherein the first heating rate is 4°C / min and the first melting temperature is 1100°C;

[0047] The method of batching with a fixed time interval between batches is as follows: the total number of batches is 5 batches, and the fixed time is 13 minutes;

[0048] The heating is carried out at a second heating rate and maintained at a constant temperature to a second melting temperature, wherein the second heating rate is 2°C / min and the second melting temperature is 1600°C;

[0049] The constant temperature smelting has a smelting time of 70 minutes.

[0050] Step 2: Molding

[0051] Preheat the graphite mold to a 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, then demould and polish it to obtain high-strength, heat-resistant glass;

[0052] The constant temperature is 800°C;

[0053] The annealing temperature is 770°C;

[0054] The constant temperature annealing is performed for 2 hours;

[0055] The temperature was lowered to room temperature at a cooling rate of 3°C / min.

[0056] Example 2: A method for preparing high-strength, heat-resistant glass

[0057] The chemical composition of the high-strength and heat-resistant glass is, by mass fraction: 70wt% SiO2, 20wt% B2O3, 2wt% Na2O, 6.72wt% K2O, 1wt% Li2O, 0.1wt% P2O5, 0.1wt% Nb2O5, 0.08wt% Re2O7;

[0058] According to the chemical composition of the high-strength and heat-resistant glass in terms of mass fraction, corresponding masses of silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifier are weighed; the potassium silicate, sodium silicate, and borate are first added to a glass melting furnace, the temperature is increased at a first heating rate and the temperature is kept constant to a first melting temperature; then, the boron trioxide is added in batches with a fixed interval between batches, the added mass of each batch being the total mass of the boron trioxide divided by the total number of batches; after the addition of the boron trioxide is completed, the temperature is increased at a second heating rate and the temperature is kept constant to a second melting temperature; then, silicon dioxide, flux, and clarifier are added, and the glass is melted at the second melting temperature; after the melting is completed, a glass melt is obtained;

[0059] The borate potassium borate;

[0060] The flux is a mixture of niobate and phosphate;

[0061] The niobate is lithium niobate;

[0062] The phosphate is lithium phosphate;

[0063] The mass ratio of the niobate to the phosphate is 3:40;

[0064] The clarifier is potassium perrhenate;

[0065] The heating is carried out at a first heating rate and maintained at a constant temperature to a first melting temperature, wherein the first heating rate is 3°C / min and the first melting temperature is 1000°C;

[0066] The method of batching with a fixed time interval between batches is as follows: the total number of batches is 3 batches, and the fixed time is 10 minutes;

[0067] The heating is carried out at a second heating rate and maintained at a constant temperature to a second melting temperature, the second heating rate is 1° C. / min, and the second melting temperature is 1550° C.;

[0068] The constant temperature smelting has a smelting time of 60 minutes.

[0069] Step 2: Molding

[0070] Preheat the graphite mold to a 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, then demould and polish it to obtain high-strength, heat-resistant glass;

[0071] The constant temperature is 700°C;

[0072] The annealing temperature is 750°C;

[0073] The constant temperature annealing is performed for 1 hour;

[0074] The temperature was lowered to room temperature at a cooling rate of 1°C / min.

[0075] Example 3: A method for preparing high-strength, heat-resistant glass

[0076] The chemical composition of the high-strength and heat-resistant glass is, by mass fraction: 84wt% SiO2, 10wt% B2O3, 2wt% Na2O, 2wt% K2O, 0.37wt% Li2O, 0.6wt% P2O5, 0.6wt% Nb2O5, 0.25wt% Re2O7, 0.1wt% Gd2O3, 0.08wt% SrO;

[0077] According to the chemical composition of the high-strength and heat-resistant glass in terms of mass fraction, corresponding masses of silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifier are weighed; the potassium silicate, sodium silicate, and borate are first added to a glass melting furnace, the temperature is increased at a first heating rate and the temperature is kept constant to a first melting temperature; then, the boron trioxide is added in batches with a fixed interval between batches, the added mass of each batch being the total mass of the boron trioxide divided by the total number of batches; after the addition of the boron trioxide is completed, the temperature is increased at a second heating rate and the temperature is kept constant to a second melting temperature; then, silicon dioxide, flux, and clarifier are added, and the glass is melted at the second melting temperature; after the melting is completed, a glass melt is obtained;

[0078] The raw materials of the high-strength, heat-resistant glass include silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifier;

[0079] The borate is lithium borate;

[0080] The flux is a mixture of niobate and phosphate;

[0081] The niobate is a mixture of lithium niobate and strontium niobate;

[0082] The phosphate is lithium phosphate;

[0083] The mass ratio of the niobate to the phosphate is 13:40;

[0084] The clarifier is a mixture of potassium perrhenate, sodium perrhenate, and gadolinium perrhenate;

[0085] The heating is carried out at a first heating rate and maintained at a constant temperature to a first melting temperature, wherein the first heating rate is 6°C / min and the first melting temperature is 1200°C;

[0086] The method of batching with a fixed time interval between batches is as follows: the total number of batches is 6 batches, and the fixed time is 20 minutes;

[0087] The heating is carried out at a second heating rate and maintained at a constant temperature to a second melting temperature, wherein the second heating rate is 4° C. / min and the second melting temperature is 1680° C.;

[0088] The constant temperature smelting has a smelting time of 100 minutes.

[0089] Step 2: Molding

[0090] Preheat the graphite mold to a 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, then demould and polish it to obtain high-strength, heat-resistant glass;

[0091] The constant temperature is 900°C;

[0092] The annealing temperature is 850°C;

[0093] The constant temperature annealing is performed for 3.5 hours;

[0094] The temperature was lowered to room temperature at a cooling rate of 4°C / min.

[0095] Example 4: A method for preparing high-strength, heat-resistant glass

[0096] Step 1: Melting

[0097] The chemical composition of the high-strength and heat-resistant glass is, by mass fraction: 70wt% SiO2, 10wt% B2O3, 2wt% Na2O, 5.72wt% K2O, 6wt% Al2O3, 3wt% MgO, 2wt% CaO, 1wt% ZnO, 0.1wt% P2O5, 0.1wt% Nb2O5, 0.08wt% Re2O7;

[0098] According to the chemical composition of the high-strength and heat-resistant glass in terms of mass fraction, corresponding masses of silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifier are weighed; the potassium silicate, sodium silicate, and borate are first added to a glass melting furnace, the temperature is increased at a first heating rate and the temperature is kept constant to a first melting temperature; then, the boron trioxide is added in batches with a fixed interval between batches, the added mass of each batch being the total mass of the boron trioxide divided by the total number of batches; after the addition of the boron trioxide is completed, the temperature is increased at a second heating rate and the temperature is kept constant to a second melting temperature; then, silicon dioxide, flux, and clarifier are added, and the glass is melted at the second melting temperature; after the melting is completed, a glass melt is obtained;

[0099] The borate is a mixture of aluminum borate, zinc borate, magnesium borate and calcium borate;

[0100] The flux is a mixture of niobate and phosphate;

[0101] The niobate is potassium niobate;

[0102] The phosphate is a mixture of magnesium phosphate, aluminum phosphate and calcium phosphate;

[0103] The mass ratio of the niobate to the phosphate is 11:40;

[0104] The clarifier is potassium perrhenate;

[0105] The heating is carried out at a first heating rate and maintained at a constant temperature to a first melting temperature, wherein the first heating rate is 4°C / min and the first melting temperature is 1100°C;

[0106] The method of batching with a fixed time interval between batches is as follows: the total number of batches is 5 batches, and the fixed time is 13 minutes;

[0107] The heating is carried out at a second heating rate and maintained at a constant temperature to a second melting temperature, wherein the second heating rate is 2°C / min and the second melting temperature is 1600°C;

[0108] The constant temperature melting is carried out for 70 minutes;

[0109] The operation of step 2 is the same as that of embodiment 1.

[0110] Example 5: A method for preparing high-strength, heat-resistant glass

[0111] The chemical composition of the high-strength and heat-resistant glass is, by mass fraction: 72.72wt% SiO2, 10wt% B2O3, 8wt% Na2O, 8wt% K2O, 1wt% Li2O, 0.1wt% P2O5, 0.1wt% Nb2O5, 0.08wt% Re2O7;

[0112] According to the chemical composition of the high-strength and heat-resistant glass in terms of mass fraction, corresponding masses of silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifier are weighed; the potassium silicate, sodium silicate, and borate are first added to a glass melting furnace, the temperature is increased at a first heating rate and the temperature is kept constant to a first melting temperature; then, the boron trioxide is added in batches with a fixed interval between batches, the added mass of each batch being the total mass of the boron trioxide divided by the total number of batches; after the addition of the boron trioxide is completed, the temperature is increased at a second heating rate and the temperature is kept constant to a second melting temperature; then, silicon dioxide, flux, and clarifier are added, and the glass is melted at the second melting temperature; after the melting is completed, a glass melt is obtained;

[0113] The borate is lithium borate;

[0114] The flux is a mixture of niobate and phosphate;

[0115] The niobate is lithium niobate;

[0116] The phosphate is lithium phosphate;

[0117] The mass ratio of the niobate to the phosphate is 9:40;

[0118] The clarifier is potassium perrhenate;

[0119] The heating is carried out at a first heating rate and maintained at a constant temperature to a first melting temperature, wherein the first heating rate is 4°C / min and the first melting temperature is 1100°C;

[0120] The method of batching with a fixed time interval between batches is as follows: the total number of batches is 5 batches, and the fixed time is 13 minutes;

[0121] The heating is carried out at a second heating rate and maintained at a constant temperature to a second melting temperature, wherein the second heating rate is 2°C / min and the second melting temperature is 1600°C;

[0122] The constant temperature melting is carried out for 70 minutes;

[0123] The operation of step 2 is the same as that of embodiment 1.

[0124] Comparative Example 1: Based on Example 1, in step 1, during melting, no borate was added, and the boron contained in the borate was replaced with the corresponding boron trioxide in equal amounts according to the stoichiometric amount. The specific operation was as follows:

[0125] Step 1: Melting

[0126] The boron contained in the borate is replaced by the corresponding boron trioxide in equal amounts according to the stoichiometric ratio, and the elements contained in the borate other than boron are replaced by the corresponding mass of silicon dioxide in equal amounts. The specific replacement method is to convert the mass of the other non-oxygen elements contained in the borate other than boron into the corresponding oxides according to the stoichiometric ratio, add up all the masses of these oxides, and the resulting value is the mass of silicon dioxide to be added. The other operations are the same as in Example 1;

[0127] The operation of step 2 is the same as that of embodiment 1.

[0128] Comparative Example 2: Based on Example 1, in step 1, during melting, no flux is added. The elements contained in the flux corresponding to the oxides in the final glass component are replaced with equal amounts of silicon dioxide of corresponding mass. The specific operation is as follows:

[0129] Step 1: Melting

[0130] The elements contained in the flux are replaced with the oxides in the final glass component by the corresponding mass of silicon dioxide. Other operations are the same as in Example 1.

[0131] The operation of step 2 is the same as that of embodiment 1.

[0132] Comparative Example 3: Based on Example 1, in step 1, during melting, an equal amount of the clarifier consisting of a mixture of potassium perrhenate, sodium perrhenate, and gadolinium perrhenate was replaced with an equal mass of sodium fluorosilicate. The specific operation was as follows:

[0133] Step 1: Melting

[0134] The clarifier consisting of a mixture of potassium perrhenate, sodium perrhenate, and gadolinium perrhenate was replaced with an equal amount of sodium fluorosilicate, and the other operations were the same as in Example 1;

[0135] The operation of step 2 is the same as that of embodiment 1.

[0136] Comparative Example 4: Based on Example 1, in step 1, during melting, the method of first adding potassium silicate, sodium silicate, and borate, and then adding boron trioxide in batches, was changed to a conventional melting process in which all raw materials were added at once. The specific operation was as follows:

[0137] Step 1: Melting

[0138] The chemical composition of the high-strength and heat-resistant glass is, by mass fraction: 76.33wt% SiO2, 12wt% B2O3, 3wt% Na2O, 4wt% K2O, 1wt% Al2O3, 1wt% MgO, 1wt% CaO, 0.5wt% ZnO, 0.5wt% Li2O, 0.2wt% P2O5, 0.3wt% Nb2O5, 0.1wt% Re2O7, 0.03wt% Gd2O3, 0.04wt% SrO;

[0139] According to the chemical composition of the high-strength and heat-resistant glass in terms of mass fraction, corresponding amounts of silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifier are weighed and all of the above raw materials are added to a glass melting furnace at once. The temperature is increased at a first heating rate and maintained at a constant temperature to a first melting temperature. After maintaining the constant temperature at the first melting temperature for the same time as in Example 1, the temperature is increased at a second heating rate and maintained at a constant temperature to a second melting temperature. The glass is then melted at the second melting temperature. After the melting is completed, a glass melt is obtained. Other operations are the same as in Example 1.

[0140] The operation of step 2 is the same as that of embodiment 1.

[0141] Performance testing:

[0142] The high-strength and heat-resistant glasses obtained in Examples 1, 2, 3, 4, and 5 and Comparative Examples 1, 2, 3, and 4 were tested for indicators such as average linear thermal expansion coefficient, softening temperature, flexural strength, impact strength, and microhardness:

[0143] 1. Average linear thermal expansion coefficient: tested in accordance with GB / T16920-2015 Determination of average linear thermal expansion coefficient of glass;

[0144] 2. Softening temperature: The softening temperature of glass is determined by the wire drawing method. The test instrument is a DNY type hanging wire method glass fixed point viscosity tester. The length of the glass wire is 235±1mm and the average diameter is 0.65mm±0.10mm. It is hung in the furnace of the test instrument and heated at a rate of 5℃ / min. The temperature at which the glass wire stretches 1mm per minute under its own gravity is defined as the softening temperature of the glass, which is usually called the Littreden point. The corresponding viscosity is about 106.6 Pa·S;

[0145] 3. Flexural strength: Use KJJ300-1 electric flexural tester, maximum load: 300N, accuracy: 1%, sample size: 50mm×4mm×2.5mm, 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 section width (mm), and H is the section thickness (mm). The flexural strength data is the average value of 10 test specimens.

[0146] 4. Impact strength: Lift a 1040g solid steel ball to a certain height and let it fall freely. The landing point should be within 25mm diameter of the center of the sample. Use a rubber ring to fill the space between the glass and the bracket. If it does not break at the first attempt, lift it to a certain height and continue to impact until the sample breaks. The height at this point is the impact strength of the glass.

[0147] 5. Microhardness: Cut the glass sample into 2.5mm thick glass slices, clean them with clean water and dry them, and make the surface smooth by grinding and polishing to facilitate observation of indentation length. Measure the hardness of the glass on the HVS-1000 digital microhardness tester. Keep the indentation on the sample surface for 15 seconds, then observe the diagonal length of the indentation. Test at least three groups of indentation lengths and take the average value. The formula for calculating 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 diagonal length of the indentation (mm);

[0148] The results are shown in Table 1:

[0149] Table 1

[0150] From the data in Table 1, we can see that the average linear thermal expansion coefficients of Examples 1-5 are all around 3.3×10 -7 / ℃ or less, the softening temperature is as high as 710℃ or more, the flexural strength is greater than 200MPa, the impact strength is about 50cm, and the microhardness is above 570MPa, which shows that the borosilicate glass prepared by the present invention has excellent properties of high strength and heat resistance. In Comparative Example 1, no borate is added, that is, during the process of adding boron trioxide in batches, the initial low-temperature melt does not contain borate, but 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 increases to 6.05×10 -7 / ℃, and the softening temperature is also reduced to 601.9. It can be seen that without the addition of borosilicate, the heat resistance is drastically deteriorated. This may be because the low-temperature melt composed of borate, potassium silicate and sodium silicate has a particularly significant effect on reducing the volatilization of boron in the hot melting process of boron trioxide, thereby ensuring that the boron content in the glass melt can meet the design requirements of the initial glass composition. The mechanical properties of Example 1 are also drastically reduced, which also shows that the addition of borate helps to reduce boron volatilization, so that a higher boron content is obtained in the final glass body; in Example 2, no borate is added to reduce the volatilization of boron, so that a higher boron content is obtained in the final glass body. The heat resistance and mechanical properties of Comparative Example 2 are reduced to the lowest values among Example 1 and all the 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 greatly improve the heat resistance and mechanical properties of the borosilicate glass. In Comparative Example 3, the clarifier composed of the mixture of potassium perrhenate, sodium perrhenate, and gadolinium perrhenate is replaced by an equal amount of sodium fluorosilicate. The heat resistance and mechanical properties of Comparative Example 3 are significantly lower than those of Example 1. The clarification 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 has a relatively strong thermal decomposition at high temperature, which can play a strong bubble stirring role on the high viscosity borosilicate glass melt, thereby promoting the fusion of tiny bubbles and accelerating the clarification efficiency of the glass melt. In addition, the Re2O7 formed after the decomposition of the perrhenate has a very good compatibility with the glass network formed by the two elements of borosilicate, which has a certain effect on the glass network. Densification plays a relatively large role, thereby promoting the improvement of various properties of borosilicate glass; in Comparative Example 4, the method of first adding potassium silicate, sodium silicate, and borate, and then adding boron trioxide in batches is changed to a conventional melting process in which all raw materials are added at one time. The heat resistance and mechanical properties of Comparative Example 4 are far worse than those of Example 1, which shows that in the conventional melting process with one-time addition, the problem of boron volatilization is difficult to avoid, which in turn affects the boron content in the final glass network, resulting in a significant reduction in the mechanical properties and heat resistance of the borosilicate glass.

[0151] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A high-strength, heat-resistant glass, characterized by: The chemical composition of the high-strength and 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, and 0-0.08wt% SrO; The raw materials of the high-strength, heat-resistant glass include silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux, and clarifier; The borate is one, any two or a mixture of any two or more 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 one of lithium niobate, potassium niobate, and 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, and 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 clarifier is one of potassium perrhenate, sodium perrhenate, and 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 method for preparing high-strength, heat-resistant glass according to claim 1, characterized in that: The method for preparing the high-strength, heat-resistant glass includes two steps: melting and forming.

4. The method for preparing high-strength, heat-resistant glass according to claim 3, characterized in that: The melting is carried out by weighing corresponding masses of silicon dioxide, boron trioxide, potassium silicate, sodium silicate, borate, flux and clarifier according to the chemical composition of the high-strength and heat-resistant glass in mass fractions. The potassium silicate, sodium silicate and borate are first added to a glass melting furnace, and the temperature is increased at a first heating rate and kept constant at a first melting temperature. Then, the boron trioxide is added in batches with a fixed time interval between batches, and the added mass of each batch is the total mass of the boron trioxide divided by the total number of batches. After the addition of the boron trioxide is completed, the temperature is increased at a second heating rate and kept constant at a second melting temperature. Then, silicon dioxide, flux and clarifier are added, and the glass is melted at the second melting temperature. After the melting is completed, a glass melt is obtained.

5. The method for preparing high-strength, heat-resistant glass according to claim 4, characterized in that: The heating is carried out at a first heating rate and maintained at a constant temperature to a first melting temperature, wherein the first heating rate is 3-6°C / min and the first melting temperature is 1000-1200°C; The method of batching with a fixed time interval between batches is as follows: the total number of batches is 3 to 6 batches, and the fixed time is 10 to 20 minutes; The second heating rate is 1-4°C / min and the second melting temperature is 1550-1680°C. The constant temperature smelting has a smelting time of 60 to 100 minutes.

6. The method for preparing high-strength, heat-resistant glass according to claim 3, characterized in that: The molding process involves preheating the graphite mold to a constant temperature in advance, then rapidly pouring the molten glass into the graphite mold while maintaining the annealing temperature. After the constant temperature annealing is completed, the temperature is lowered to room temperature, and then demolding and polishing are performed to obtain high-strength, heat-resistant glass.

7. The method for preparing high-strength, heat-resistant glass according to claim 6, characterized in that: The constant temperature is 700-900°C; The annealing temperature is 750-850°C; The constant temperature annealing time is 1 to 3.5 hours; The temperature is lowered to room temperature at a rate of 1-4°C / min.

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