A thermal shock resistant, high-toughness borosilicate glass and its preparation method

Abstract

This invention discloses a thermally shock resistant, high-toughness borosilicate glass and its preparation method, relating to the field of glass manufacturing technology. The raw materials for the thermally shock resistant, high-toughness borosilicate glass include silicon dioxide, boron oxide, aluminum oxide, magnesium oxide, sodium oxide, potassium oxide, SiC@SiO2-B2O3 nanowhiskers, and rare earth pre-melted frit. The preparation method includes the steps of preparing SiC@SiO2-B2O3 nanowhiskers, preparing rare earth pre-melted frit, forming a glass substrate, and obtaining the finished glass product. The raw materials used to prepare SiC@SiO2-B2O3 nanowhiskers include β-SiC nanowhiskers, tetraethyl orthosilicate, and boric acid. The raw materials used to prepare the rare earth pre-melted frit include lanthanum oxide, ytterbium oxide, boric acid, and quartz powder. The borosilicate glass prepared by this invention exhibits strong mechanical properties and excellent thermal shock resistance.

Description

Technical Field

[0001] This invention relates to the field of glass manufacturing technology, specifically to a thermal shock resistant, high-toughness borosilicate glass and its preparation method. Background Technology

[0002] Borosilicate glass, with its low coefficient of thermal expansion, excellent high-temperature resistance, chemical stability, and optical transmittance, is widely used in laboratory glassware, kitchen utensils, solar collector tubes, electronic component packaging, and aerospace windows, making it an indispensable key material in modern industry.

[0003] Traditional borosilicate glass is inherently a brittle material with low fracture toughness and insufficient thermal shock resistance. It is highly susceptible to brittle fracture under rapid temperature changes or mechanical impacts, especially under rapid heating and cooling conditions exceeding 150°C. This results in significant thermal stress concentration within the glass, causing microcracks to propagate rapidly and eventually shatter, severely shortening product lifespan and posing safety hazards. To address this deficiency, existing technologies primarily modify the composition by introducing oxides such as zirconium oxide and alumina. Ion exchange tempering, however, suffers from poor ion diffusion due to the low alkali metal content and dense network structure of high-borosilicate glass, resulting in only a very thin tempered layer that is easily scratched and fails. Ordinary nanoparticle doping methods suffer from severe particle agglomeration and weak interfacial bonding, leading to extremely low toughening efficiency and a significant decrease in light transmittance. Direct doping with single rare earth oxides is problematic because the high melting point of rare earth oxides makes them difficult to completely dissolve at glass melting temperatures, easily forming unmelted stones and streaks, resulting in poor rare earth utilization. The prior art disclosed in CN118373591A is a thermal shock resistant transparent high borosilicate glass and its preparation method. This prior art uses ionic liquid to improve the dispersibility and interfacial bonding of quartz sand, reduces internal bubbles in the glass by using hydroxyl silicone oil, and improves performance by precipitating nanocrystalline phases through high-temperature crystallization treatment. However, this prior art relies solely on crystallization to precipitate nanocrystalline phases, resulting in low toughening efficiency and limited improvement in thermal shock resistance. Furthermore, it does not employ surface strengthening processes, leading to limited surface hardness and scratch resistance.

[0004] In summary, although the existing technical solutions have improved some properties of thermal shock resistant borosilicate glass to a certain extent, the following technical problems still exist: poor mechanical properties and insufficient thermal shock resistance. Summary of the Invention

[0005] In order to solve the above-mentioned problems in the prior art, the present invention provides a thermal shock resistant high-toughness borosilicate glass and its preparation method, and achieves the following objective: to prepare borosilicate glass with strong mechanical properties and excellent thermal shock resistance.

[0006] To achieve the above objectives, the following technical solution is adopted: A method for preparing thermal shock resistant and high-toughness borosilicate glass includes the steps of preparing SiC@SiO2-B2O3 nanocrystals, preparing rare earth pre-melted ingots, forming glass substrates, and obtaining finished glass products.

[0007] The preparation of SiC@SiO2-B2O3 nanocrystals is as follows: β-SiC nanocrystals are placed in a tube furnace, air is introduced at a flow rate of 200-210 mL / min, the temperature is raised to 1100-1120℃ at a heating rate of 5-7℃ / min, and held at this temperature for 150-160 min; after holding, the temperature is cooled to room temperature at a cooling rate of 10-12℃ / min to obtain SiC@SiO2 nanocrystals; tetraethyl orthosilicate is added to anhydrous ethanol and stirred until completely dissolved to obtain a tetraethyl orthosilicate ethanol solution; boric acid is added to deionized water, the temperature is raised to 60-65℃, and stirred until completely dissolved to obtain a boric acid solution; the boric acid solution is added dropwise to the tetraethyl orthosilicate ethanol solution, and stirred for 10-15 min at a rotation speed of 2... Stir at 00-300 rpm, then adjust the pH of the solution to 3.2-3.5 with hydrochloric acid, control the temperature at 60-65℃, and stir for 2-2.5 h to obtain SiO2-B2O3 sol; add SiC@SiO2 nanocrystals to the SiO2-B2O3 sol, ultrasonically disperse for 30-40 min with an ultrasonic power of 200-250 W, control the temperature at 60-65℃, and stir for 5-6 h, ultrasonically dispersing for 10 min every 1 h during the reaction; after the reaction, collect the solid by centrifugation, wash 3-4 times with anhydrous ethanol, and vacuum dry; then grind through a 200-mesh sieve, calcine, and cool to room temperature at a cooling rate of 10-12℃ / min to obtain SiC@SiO2-B2O3 nanocrystals.

[0008] Further, the tetraethyl orthosilicate ethanol solution has a tetraethyl orthosilicate mass fraction of 17-19%. The boric acid solution has a boric acid mass fraction of 10-12%. The mass ratio of the boric acid solution to the tetraethyl orthosilicate ethanol solution is 1:(7.5-8). The mass ratio of the SiC@SiO2 nanocrystals to the SiO2-B2O3 sol is 1:(25-30). Vacuum drying: temperature is 80-85℃, vacuum degree is -0.09MPa to -0.095MPa, drying time is 23-24h. Calcination treatment: the ground powder is placed in a tube furnace, air is first introduced at a flow rate of 100-150mL / min, the temperature is raised to 300-310℃, and held for 1-2h; then argon gas is introduced at a flow rate of 300-320mL / min, the temperature is raised to 800-810℃, and held for 1-1.5h.

[0009] The preparation of rare earth pre-melted frit involves mixing lanthanum oxide, ytterbium oxide, boric acid, and quartz powder, ball milling the mixture to obtain a mixed powder, placing the mixed powder in an electric furnace, and melting it with a gradient heating process, then rapidly pouring the molten glass into deionized water for water quenching, vacuum drying, and pulverizing it through a 200-mesh sieve to obtain the rare earth pre-melted frit.

[0010] Further, the mass ratio of lanthanum oxide, ytterbium oxide, boric acid, and quartz powder is (27-30):(25-28):(28-32):(4-6). The ball milling process involves a ball-to-material ratio of 5:1, a rotation speed of 350-400 rpm, and milling for 3-3.5 hours. The gradient heating and melting process involves first heating to 800-810℃ at a rate of 5-7℃ / min and holding for 1-1.5 hours; then heating to 1290-1310℃ at a rate of 5-7℃ / min and holding for 1.5-2 hours. The vacuum drying process involves a temperature of 120-125℃, a vacuum degree of -0.09MPa to -0.095MPa, and drying for 11-12 hours.

[0011] The glass substrate forming process involves uniformly mixing silicon dioxide, boron oxide, aluminum oxide, magnesium oxide, sodium oxide, potassium oxide, and SiC@SiO2-B2O3 nanocrystals, adding the mixture to an electric furnace for melting, then adding rare earth pre-melted blocks, stirring for 5-8 minutes at a speed of 200-300 rpm, holding at the temperature for 20-25 minutes, then cooling to 1240-1250℃ at a cooling rate of 10-12℃ / min, adding the mixture to a graphite mold, controlling the temperature at 1240-1250℃, slowly applying pressure to 18-20 MPa, and holding at the temperature and pressure for 30-40 minutes; then releasing the pressure and performing annealing treatment to obtain the glass substrate.

[0012] Furthermore, the raw materials used are proportioned as follows by weight: 65-72 parts silicon dioxide, 15-20 parts boron oxide, 4-7 parts aluminum oxide, 2-4 parts magnesium oxide, 1.5-2.5 parts sodium oxide, 1-1.5 parts potassium oxide, 2-3.5 parts SiC@SiO2-B2O3 nanocrystals, and 1-1.5 parts rare earth pre-melted frit. The melting process involves first heating from room temperature to 800-810℃ at a rate of 5-7℃ / min and holding at that temperature for 60-70 min; then heating to 1440-1450℃ at a rate of 5-7℃ / min and holding at that temperature for 60-70 min. The annealing process involves first cooling to 600-610℃ at a rate of 10-12℃ / min, then cooling to 540-550℃ at a rate of 2-3℃ / min, and holding at that temperature for 2-2.5 hours; then cooling to 290-300℃ at a rate of 1-2℃ / min, and finally cooling to room temperature at a rate of 3-4℃ / min.

[0013] The glass product is prepared by: mixing potassium nitrate, potassium hydroxide, and potassium carbonate evenly, heating to 400-410℃, stirring until completely melted, and holding at this temperature for 2-2.5 hours to obtain ion exchange molten salt; immersing the glass substrate in the ion exchange molten salt, controlling the temperature at 400±5℃, and holding at this temperature for 6-6.5 hours; then slowly removing the glass substrate, cooling it to 300-310℃, holding it at this temperature for 30-40 minutes, and then cooling it to room temperature; rinsing the surface with deionized water to remove residual molten salt, then wiping it clean with anhydrous ethanol, and drying it to obtain the glass product.

[0014] Furthermore, the mass ratio of potassium nitrate, potassium hydroxide, and potassium carbonate is (85-90):(3-5):(3-5). The drying process involves drying at 120-130℃ for 1-1.5 hours.

[0015] The beneficial effects of this invention are as follows: (1) The SiC@SiO2-B2O3 nanocrystals of the present invention provide high strength and high modulus mechanical support through the β-SiC core, which serves as the core carrier for stress transfer and bears the external load in the glass matrix. The in-situ oxidized SiO2 inner layer forms covalent bonds with the SiC core, improving the interfacial bonding strength. The chemical composition of the SiO2-B2O3 outer layer is basically consistent with that of the borosilicate glass matrix, achieving excellent chemical compatibility and near-atomic level interfacial matching. A specific amount of SiC@SiO2-B2O3 nanocrystals forms a three-dimensional network structure inside the glass, providing a rapid diffusion channel for ion exchange. + Ions preferentially diffuse along the whisker-matrix interface, increasing the depth and uniformity of the compressive stress layer and further improving the mechanical properties of the glass.

[0016] The rare earth pre-melted frit of this invention, through a pre-melting process, transforms high-melting-point rare earth oxides into low-melting-point rare earth borosilicate glass frits, thereby improving rare earth utilization and eliminating unmelted rare earth particles and agglomerates; it greatly improves compositional uniformity, avoiding localized compositional fluctuations caused by direct addition; and it reduces rare earth volatilization losses, as rare earths first form a stable [BO4]-RE with B2O3. 3+ The structure significantly reduces the risk of rare earth elements reacting with alkali metals to form volatile compounds. Rare earth ions preferentially accumulate at the interface between SiC@SiO2-B2O3 whiskers and the glass substrate, reacting with hydroxyl groups on the whisker surface to form Si-O-La and Si-O-Yb chemical bonds, further improving the interfacial bonding strength. A rare earth borosilicate transition layer is formed on the whisker surface, further optimizing the matching of the interface's thermal expansion coefficient.

[0017] (2) The thermal shock resistant and high-toughness borosilicate glass of this invention possesses excellent mechanical properties. The fracture toughness of the prepared glass product is 5.08-5.21 MPa. m 1 / 2Its flexural strength is 634-658 MPa.

[0018] (3) The thermal shock resistant high-toughness borosilicate glass of the present invention has excellent thermal shock resistance. In the thermal shock cycle test, the prepared glass product has a thermal shock cycle count of 28-33 when the specimen breaks. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0020] Example 1: A thermal shock resistant, high-toughness borosilicate glass and its preparation method A method for preparing thermal shock resistant and high-toughness borosilicate glass, comprising the following steps: Step 1: Preparation of SiC@SiO2-B2O3 nanocrystals β-SiC nanocrystals were placed in a tube furnace, air was introduced at a flow rate of 200 mL / min, the temperature was raised to 1100℃ at a rate of 5℃ / min, and held for 160 min. After the holding period, the temperature was cooled to room temperature at a rate of 10℃ / min to obtain SiC@SiO2 nanocrystals. Tetraethyl orthosilicate was added to anhydrous ethanol and stirred until completely dissolved to obtain a tetraethyl orthosilicate ethanol solution. Boric acid is added to deionized water, heated to 60°C, and stirred until completely dissolved to obtain a boric acid solution. Boric acid solution was added dropwise to tetraethyl orthosilicate ethanol solution, stirred for 10 min at 300 rpm, then the pH of the solution was adjusted to 3.2 with hydrochloric acid, the temperature was controlled at 60℃, and the reaction was stirred for 2.5 h to obtain SiO2-B2O3 sol. The tetraethyl orthosilicate ethanol solution has a tetraethyl orthosilicate mass fraction of 17%.

[0021] The boric acid solution has a boric acid mass fraction of 10%.

[0022] The mass ratio of the boric acid solution to the tetraethyl orthosilicate ethanol solution is 1:7.5.

[0023] SiC@SiO2 nanocrystals were added to SiO2-B2O3 sol and ultrasonically dispersed for 30 min at a power of 250 W at a controlled temperature of 60 °C. The mixture was stirred for 6 h with ultrasonic dispersion for 10 min every h during the reaction. After the reaction, the solid was collected by centrifugation, washed three times with anhydrous ethanol, and vacuum dried. The solid was then ground through a 200-mesh sieve and calcined. It was then cooled to room temperature at a rate of 10 °C / min to obtain SiC@SiO2-B2O3 nanocrystals.

[0024] The mass ratio of SiC@SiO2 nanocrystals to SiO2-B2O3 sol is 1:25.

[0025] Vacuum drying: temperature 80℃, vacuum degree -0.09MPa, drying for 24h.

[0026] The calcination process involves placing the ground powder into a tube furnace, first introducing air at a flow rate of 100 mL / min, heating to 300°C, and holding for 2 hours; then introducing argon at a flow rate of 300 mL / min, heating to 800°C, and holding for 1.5 hours.

[0027] Step 2: Preparation of rare earth pre-melted ingots Lanthanum oxide, ytterbium oxide, boric acid, and quartz powder were mixed and ball-milled to obtain a mixed powder. The mixed powder was then placed in an electric furnace and melted by gradient heating. The molten glass was then quickly poured into deionized water for water quenching, vacuum drying, and pulverized through a 200-mesh sieve to obtain rare earth pre-melted frit.

[0028] The mass ratio of lanthanum oxide, ytterbium oxide, boric acid, and quartz powder is 27:25:28:4.

[0029] The ball milling process involved a ball-to-material ratio of 5:1, a rotation speed of 350 rpm, and a milling time of 3.5 hours.

[0030] The gradient heating melting process involves first heating to 800℃ at a rate of 5℃ / min and holding at that temperature for 1.5 hours; then heating to 1290℃ at a rate of 5℃ / min and holding at that temperature for 2 hours.

[0031] The vacuum drying process involves a temperature of 120°C, a vacuum degree of -0.09 MPa, and a drying time of 12 hours.

[0032] Step 3: Glass substrate molding Silica, boron oxide, aluminum oxide, magnesium oxide, sodium oxide, potassium oxide, and SiC@SiO2-B2O3 nanocrystals were mixed evenly and added to an electric furnace for melting. Then, rare earth pre-melted blocks were added, and the mixture was stirred for 5 minutes at 300 rpm and held at that temperature for 20 minutes. The temperature was then lowered to 1240℃ at a rate of 10℃ / min and added to a graphite mold. The temperature was controlled at 1240℃, and the pressure was slowly applied to 18 MPa and held at that temperature and pressure for 40 minutes. The pressure was then released, and the mixture was annealed to obtain a glass substrate.

[0033] The raw materials used are in the following weight proportions: 65 parts silicon dioxide, 20 parts boron oxide, 4 parts aluminum oxide, 4 parts magnesium oxide, 1.5 parts sodium oxide, 1.5 parts potassium oxide, 2 parts SiC@SiO2-B2O3 nanocrystals, and 1.5 parts rare earth pre-melted molten blocks.

[0034] The melting process involves first heating from room temperature to 800°C at a rate of 5°C / min and holding at that temperature for 70 min; then heating to 1440°C at a rate of 5°C / min and holding at that temperature for 70 min.

[0035] The annealing process involves first cooling to 600°C at a rate of 10°C / min, then cooling to 540°C at a rate of 2°C / min and holding at that temperature for 2.5 hours; then cooling to 290°C at a rate of 1°C / min, and finally cooling to room temperature at a rate of 3°C / min.

[0036] Step 4: Obtain the finished glass product Potassium nitrate, potassium hydroxide, and potassium carbonate are mixed evenly, heated to 400℃, stirred until completely melted, and kept at this temperature for 2.5 hours to obtain ion-exchange molten salt. The glass substrate is immersed in ion-exchange molten salt at a controlled temperature of 400±5℃ for 6 hours. Then, the glass substrate is slowly removed, cooled to 300℃, held for 40 minutes, and then cooled to room temperature. The surface is rinsed with deionized water to remove any remaining molten salt, wiped clean with anhydrous ethanol, and dried to obtain the finished glass product.

[0037] The mass ratio of potassium nitrate, potassium hydroxide, and potassium carbonate is 85:3:3.

[0038] The drying process involves drying at 120°C for 1.5 hours.

[0039] Example 2: A thermal shock resistant, high-toughness borosilicate glass and its preparation method A method for preparing thermal shock resistant and high-toughness borosilicate glass, comprising the following steps: Step 1: Preparation of SiC@SiO2-B2O3 nanocrystals β-SiC nanocrystals were placed in a tube furnace, air was introduced at a flow rate of 200 mL / min, the temperature was raised to 1110℃ at a rate of 6℃ / min, and held for 160 min. After the holding period, the temperature was cooled to room temperature at a rate of 12℃ / min to obtain SiC@SiO2 nanocrystals. Tetraethyl orthosilicate was added to anhydrous ethanol and stirred until completely dissolved to obtain a tetraethyl orthosilicate ethanol solution. Boric acid is added to deionized water, heated to 65°C, and stirred until completely dissolved to obtain a boric acid solution. Boric acid solution was added dropwise to tetraethyl orthosilicate ethanol solution, stirred for 15 min at 300 rpm, then the pH of the solution was adjusted to 3.3 with hydrochloric acid, the temperature was controlled at 65℃, and the reaction was stirred for 2.5 h to obtain SiO2-B2O3 sol. The tetraethyl orthosilicate ethanol solution has a tetraethyl orthosilicate mass fraction of 18%.

[0040] The boric acid solution has a boric acid mass fraction of 10%.

[0041] The mass ratio of the boric acid solution to the tetraethyl orthosilicate ethanol solution is 1:7.8.

[0042] SiC@SiO2 nanocrystals were added to SiO2-B2O3 sol and ultrasonically dispersed for 35 min at an ultrasonic power of 200 W at a controlled temperature of 65 °C. The mixture was stirred and reacted for 6 h, with ultrasonic dispersion for 10 min every 1 h during the reaction. After the reaction, the solid was collected by centrifugation, washed four times with anhydrous ethanol, and vacuum dried. Then, it was ground through a 200-mesh sieve and calcined. The solid was then cooled to room temperature at a cooling rate of 12 °C / min to obtain SiC@SiO2-B2O3 nanocrystals.

[0043] The mass ratio of SiC@SiO2 nanocrystals to SiO2-B2O3 sol is 1:28.

[0044] Vacuum drying: temperature 85℃, vacuum degree -0.095MPa, drying for 24h.

[0045] The calcination process involves placing the ground powder into a tube furnace, first introducing air at a flow rate of 150 mL / min, heating to 310°C, and holding at that temperature for 1.5 hours; then introducing argon gas at a flow rate of 310 mL / min, heating to 810°C, and holding at that temperature for 1.5 hours.

[0046] Step 2: Preparation of rare earth pre-melted ingots Lanthanum oxide, ytterbium oxide, boric acid, and quartz powder were mixed and ball-milled to obtain a mixed powder. The mixed powder was then placed in an electric furnace and melted by gradient heating. The molten glass was then quickly poured into deionized water for water quenching, vacuum drying, and pulverized through a 200-mesh sieve to obtain rare earth pre-melted frit.

[0047] The mass ratio of lanthanum oxide, ytterbium oxide, boric acid, and quartz powder is 28:26:30:5.

[0048] The ball milling process involved a ball-to-material ratio of 5:1, a rotation speed of 400 rpm, and a milling time of 3.5 hours.

[0049] The gradient heating melting process involves first heating to 810℃ at a rate of 6℃ / min and holding for 1.5 hours; then heating to 1300℃ at a rate of 7℃ / min and holding for 2 hours.

[0050] The vacuum drying process involves a temperature of 125°C, a vacuum degree of -0.095 MPa, and a drying time of 12 hours.

[0051] Step 3: Glass substrate molding Silica, boron oxide, aluminum oxide, magnesium oxide, sodium oxide, potassium oxide, and SiC@SiO2-B2O3 nanocrystals were mixed evenly and added to an electric furnace for melting. Then, rare earth pre-melted blocks were added, and the mixture was stirred for 8 minutes at 300 rpm and held at that temperature for 25 minutes. The temperature was then lowered to 1250℃ at a rate of 12℃ / min and added to a graphite mold. The temperature was controlled at 1250℃, and the pressure was slowly applied to 20 MPa and held for 40 minutes. The pressure was then released, and the mixture was annealed to obtain a glass substrate.

[0052] The raw materials used are in the following weight proportions: 70 parts silicon dioxide, 18 parts boron oxide, 6 parts aluminum oxide, 3 parts magnesium oxide, 2 parts sodium oxide, 1.5 parts potassium oxide, 3 parts SiC@SiO2-B2O3 nanocrystals, and 1.5 parts rare earth pre-melted molten blocks.

[0053] The melting process involves first heating from room temperature to 810°C at a rate of 6°C / min and holding at that temperature for 70 min; then heating to 1450°C at a rate of 6°C / min and holding at that temperature for 65 min.

[0054] The annealing process involves first cooling to 610°C at a rate of 12°C / min, then cooling to 550°C at a rate of 3°C / min and holding at that temperature for 2.5 hours; then cooling to 300°C at a rate of 2°C / min, and finally cooling to room temperature at a rate of 4°C / min.

[0055] Step 4: Obtain the finished glass product Potassium nitrate, potassium hydroxide, and potassium carbonate are mixed evenly, heated to 410℃, stirred until completely melted, and kept at this temperature for 2.5 hours to obtain ion-exchange molten salt. The glass substrate is immersed in ion-exchange molten salt at a controlled temperature of 400±5℃ for 6.5 hours. Then, the glass substrate is slowly removed, cooled to 310℃, held for 30 minutes, and then cooled to room temperature. The surface is rinsed with deionized water to remove any remaining molten salt, wiped clean with anhydrous ethanol, and dried to obtain the finished glass product.

[0056] The mass ratio of potassium nitrate, potassium hydroxide, and potassium carbonate is 88:4:4.

[0057] The drying process involves drying at 125°C for 1.5 hours.

[0058] Example 3: A thermal shock resistant, high-toughness borosilicate glass and its preparation method A method for preparing thermal shock resistant and high-toughness borosilicate glass, comprising the following steps: Step 1: Preparation of SiC@SiO2-B2O3 nanocrystals β-SiC nanocrystals were placed in a tube furnace, air was introduced at a flow rate of 210 mL / min, the temperature was raised to 1120℃ at a rate of 7℃ / min, and held for 150 min. After the holding period, the temperature was cooled to room temperature at a rate of 12℃ / min to obtain SiC@SiO2 nanocrystals. Tetraethyl orthosilicate was added to anhydrous ethanol and stirred until completely dissolved to obtain a tetraethyl orthosilicate ethanol solution. Boric acid is added to deionized water, heated to 65°C, and stirred until completely dissolved to obtain a boric acid solution. Boric acid solution was added dropwise to tetraethyl orthosilicate ethanol solution, stirred for 15 min at 200 rpm, then the pH of the solution was adjusted to 3.5 with hydrochloric acid, the temperature was controlled at 65℃, and the reaction was stirred for 2 h to obtain SiO2-B2O3 sol. The tetraethyl orthosilicate ethanol solution has a tetraethyl orthosilicate mass fraction of 19%.

[0059] The boric acid solution has a boric acid mass fraction of 12%.

[0060] The mass ratio of the boric acid solution to the tetraethyl orthosilicate ethanol solution is 1:8.

[0061] SiC@SiO2 nanocrystals were added to SiO2-B2O3 sol and ultrasonically dispersed for 40 min at a power of 200 W at a controlled temperature of 65 °C. The mixture was stirred for 5 h with ultrasonic dispersion for 10 min every h during the reaction. After the reaction, the solid was collected by centrifugation, washed four times with anhydrous ethanol, and vacuum dried. The solid was then ground through a 200-mesh sieve and calcined. It was then cooled to room temperature at a rate of 12 °C / min to obtain SiC@SiO2-B2O3 nanocrystals.

[0062] The mass ratio of SiC@SiO2 nanocrystals to SiO2-B2O3 sol is 1:30.

[0063] Vacuum drying: temperature 85℃, vacuum degree -0.095MPa, drying for 23h.

[0064] The calcination process involves placing the ground powder into a tube furnace, first introducing air at a flow rate of 150 mL / min, heating to 310°C, and holding for 1 hour; then introducing argon gas at a flow rate of 320 mL / min, heating to 810°C, and holding for 1 hour.

[0065] Step 2: Preparation of rare earth pre-melted ingots Lanthanum oxide, ytterbium oxide, boric acid, and quartz powder were mixed and ball-milled to obtain a mixed powder. The mixed powder was then placed in an electric furnace and melted by gradient heating. The molten glass was then quickly poured into deionized water for water quenching, vacuum drying, and pulverized through a 200-mesh sieve to obtain rare earth pre-melted frit.

[0066] The mass ratio of lanthanum oxide, ytterbium oxide, boric acid, and quartz powder is 30:28:32:6.

[0067] The ball milling process involved a ball-to-material ratio of 5:1, a rotation speed of 400 rpm, and a milling time of 3 hours.

[0068] The gradient heating melting process involves first heating to 810℃ at a rate of 7℃ / min and holding for 1 hour; then heating to 1310℃ at a rate of 7℃ / min and holding for 1.5 hours.

[0069] The vacuum drying process involves a temperature of 125°C, a vacuum degree of -0.095 MPa, and a drying time of 11 hours.

[0070] Step 3: Glass substrate molding Silica, boron oxide, aluminum oxide, magnesium oxide, sodium oxide, potassium oxide, and SiC@SiO2-B2O3 nanocrystals were mixed evenly and added to an electric furnace for melting. Then, rare earth pre-melted blocks were added, and the mixture was stirred for 8 minutes at 200 rpm and held at that temperature for 25 minutes. The temperature was then lowered to 1250℃ at a rate of 12℃ / min and added to a graphite mold. The temperature was controlled at 1250℃, and a pressure of 20 MPa was slowly applied and held at that temperature and pressure for 30 minutes. The pressure was then released, and the mixture was annealed to obtain a glass substrate.

[0071] The raw materials used are in the following weight proportions: 72 parts silicon dioxide, 15 parts boron oxide, 7 parts aluminum oxide, 2 parts magnesium oxide, 2.5 parts sodium oxide, 1 part potassium oxide, 3.5 parts SiC@SiO2-B2O3 nanocrystals, and 1 part rare earth pre-melted molten block.

[0072] The melting process involves first heating from room temperature to 810°C at a rate of 7°C / min and holding at that temperature for 60 min; then heating to 1450°C at a rate of 7°C / min and holding at that temperature for 60 min.

[0073] The annealing process involves first cooling to 610°C at a rate of 12°C / min, then cooling to 550°C at a rate of 3°C / min and holding for 2 hours; then cooling to 300°C at a rate of 2°C / min, and finally cooling to room temperature at a rate of 4°C / min.

[0074] Step 4: Obtain the finished glass product Potassium nitrate, potassium hydroxide, and potassium carbonate are mixed evenly, heated to 410℃, stirred until completely melted, and kept at this temperature for 2 hours to obtain ion exchange molten salt. The glass substrate is immersed in ion-exchange molten salt at a controlled temperature of 400±5℃ for 6.5 hours. Then, the glass substrate is slowly removed, cooled to 310℃, held for 30 minutes, and then cooled to room temperature. The surface is rinsed with deionized water to remove any remaining molten salt, wiped clean with anhydrous ethanol, and dried to obtain the finished glass product.

[0075] The mass ratio of potassium nitrate, potassium hydroxide, and potassium carbonate is 90:5:5.

[0076] The drying process involves drying at 130°C for 1 hour.

[0077] Comparative Example 1 A method for preparing thermal shock resistant and high-toughness borosilicate glass, comprising the following steps: Step 1: Preparation of rare earth pre-melted frit This step is the same as the "Preparation of rare earth pre-melted frit" step in Example 2.

[0078] Step 2: Glass substrate molding In this step, SiC@SiO2-B2O3 nanocrystals are not added, and the other operations are the same as the "glass substrate forming" step in Example 2.

[0079] Step 3: Obtain the finished glass product This step is the same as the "obtaining the finished glass product" step in Example 2.

[0080] Comparative Example 2 A method for preparing thermal shock resistant and high-toughness borosilicate glass, comprising the following steps: Step 1: Preparation of SiC@SiO2-B2O3 nanocrystals This step is the same as the "Preparation of SiC@SiO2-B2O3 nanocrystals" step in Example 2.

[0081] Step 2: Glass substrate molding In this step, no rare earth pre-melted molten block is added, and the other operations are the same as the "glass substrate forming" step in Example 2.

[0082] Step 3: Obtain the finished glass product This step is the same as the "obtaining the finished glass product" step in Example 2.

[0083] Example 4 Performance Testing (I) Mechanical property tests were conducted on the glass products prepared in Examples 1-3 and Comparative Examples 1-2. Fracture toughness was tested according to the test methods specified in GB / T37900-2019, with samples prepared as square specimens with a side length of 40 mm and a thickness of 1 mm. Bending strength was tested on the prepared glass products, with samples prepared as specimens with a length of 100 mm, a width of 15 mm, and a thickness of 1 mm, using a universal testing machine with a span of 50 mm. Specific test results are shown in Table 1.

[0084] Table 1 As shown in Table 1, the fracture toughness of the glass products prepared in Examples 1-3 is 5.08-5.21 MPa. m 1 / 2 The bending strength is 634-658 MPa, which proves that the borosilicate glass prepared by this invention has excellent mechanical properties.

[0085] (II) The thermal shock resistance of the glass products prepared in Examples 1-3 and Comparative Examples 1-2 was tested. Samples were prepared as specimens with a diameter of 50 mm and a thickness of 2.8 mm. Thermal shock cycling was performed as follows: the specimen was placed in an oven at 370°C for 10 minutes, then immediately immersed in a cold water bath at 20°C for 30 seconds. This process was repeated, and the number of thermal shock cycles at which the specimen broke was recorded. Specific test results are shown in Table 2.

[0086] Table 2 As shown in Table 2, the glass products prepared in Examples 1-3 exhibited 28-33 thermal shock cycles before cracking during the thermal shock cycle test. This demonstrates that the borosilicate glass prepared according to this invention possesses excellent thermal shock resistance.

[0087] The specific parameters of the raw materials used in this invention are as follows: The β-SiC nanocrystals have a diameter of 30-50 nm, an aspect ratio of 20-30, and a purity of ≥99.5%.

[0088] The quartz powder has a particle size of 5-10 μm.

[0089] The SiO2 content of the tetraethyl orthosilicate is ≥29%.

[0090] Obviously, there are many other possible implementation methods under the concept of this invention. It should be stated here that any changes made under the inventive concept of this invention will fall within the protection scope of this invention.

Claims

1. A method for preparing thermally shock resistant, high-toughness borosilicate glass, characterized in that: The process includes steps such as preparing SiC@SiO2-B2O3 nanocrystals, preparing rare earth pre-melted ingots, forming glass substrates, and obtaining finished glass products. The preparation of SiC@SiO2-B2O3 nanocrystals involves placing β-SiC nanocrystals in a tube furnace, purging air, heating, and maintaining the temperature. Cooling yields SiC@SiO2 nanocrystals; tetraethyl orthosilicate is dissolved in anhydrous ethanol to obtain a tetraethyl orthosilicate ethanol solution; boric acid is dissolved in deionized water to obtain a boric acid solution; the boric acid solution is added dropwise to the tetraethyl orthosilicate ethanol solution, stirred, the pH of the solution is adjusted, and the reaction is stirred to obtain SiO2-B2O3 sol; SiC@SiO2 nanocrystals are added, ultrasonically dispersed, and the reaction is stirred; after centrifugation, washing, vacuum drying, grinding and sieving, calcination, and cooling, SiC@SiO2-B2O3 nanocrystals are obtained. The preparation of rare earth pre-melted frit involves ball milling lanthanum oxide, ytterbium oxide, boric acid, and quartz powder to obtain a mixed powder; then placing it in an electric furnace for gradient heating and melting; followed by water quenching, vacuum drying, pulverizing, and sieving to obtain the rare earth pre-melted frit. The glass substrate is formed by mixing silicon dioxide, boron oxide, aluminum oxide, magnesium oxide, sodium oxide, potassium oxide, and SiC@SiO2-B2O3 nanocrystals evenly, melting them, adding rare earth pre-melted molten blocks, keeping the temperature, then cooling them down, adding them into a graphite mold, controlling the temperature, applying pressure, and keeping the temperature and pressure; after depressurization, annealing is performed to obtain the glass substrate. The glass product is obtained by: mixing potassium nitrate, potassium hydroxide, and potassium carbonate evenly, heating to melt, and holding at the temperature to obtain ion exchange molten salt; immersing the glass substrate in the ion exchange molten salt and holding at the temperature; removing the glass substrate, cooling and holding at the temperature, and then rinsing and drying to obtain the glass product.

2. The method for preparing thermally shock resistant, high-toughness borosilicate glass according to claim 1, characterized in that: In the step of preparing SiC@SiO2-B2O3 nanocrystals, the mass fraction of tetraethyl orthosilicate in the tetraethyl orthosilicate ethanol solution is 17-19%; and the mass fraction of boric acid in the boric acid solution is 10-12%.

3. The method for preparing thermally shock resistant, high-toughness borosilicate glass according to claim 1, characterized in that: In the step of preparing SiC@SiO2-B2O3 nanocrystals, the mass ratio of boric acid solution to tetraethyl orthosilicate ethanol solution is 1:(7.5-8).

4. The method for preparing thermally shock resistant, high-toughness borosilicate glass according to claim 1, characterized in that: In the step of preparing SiC@SiO2-B2O3 nanocrystals, the mass ratio of SiC@SiO2 nanocrystals to SiO2-B2O3 sol is 1:(25-30).

5. The method for preparing a thermally shock resistant, high-toughness borosilicate glass according to claim 1, characterized in that: In the step of preparing SiC@SiO2-B2O3 nanocrystals, the calcination treatment is as follows: the ground powder is placed in a tube furnace, air is first introduced at a flow rate of 100-150 mL / min, the temperature is raised to 300-310℃, and the temperature is held for 1-2 h; then argon gas is introduced at a flow rate of 300-320 mL / min, the temperature is raised to 800-810℃, and the temperature is held for 1-1.5 h.

6. The method for preparing a thermally shock resistant, high-toughness borosilicate glass according to claim 1, characterized in that: In the step of preparing rare earth pre-melted frit, the mass ratio of lanthanum oxide, ytterbium oxide, boric acid and quartz powder is (27-30):(25-28):(28-32):(4-6).

7. The method for preparing thermally shock resistant, high-toughness borosilicate glass according to claim 1, characterized in that: In the step of preparing rare earth pre-melted frit, the temperature is increased by gradient: first, the temperature is increased to 800-810℃ at a rate of 5-7℃ / min, and then held for 1-1.5h; then the temperature is increased to 1290-1310℃ at a rate of 5-7℃ / min, and held for 1.5-2h.

8. The method for preparing a thermally shock resistant, high-toughness borosilicate glass according to claim 1, characterized in that: In the glass substrate forming step, the raw materials are proportioned as follows by weight: 65-72 parts silicon dioxide, 15-20 parts boron oxide, 4-7 parts aluminum oxide, 2-4 parts magnesium oxide, 1.5-2.5 parts sodium oxide, 1-1.5 parts potassium oxide, 2-3.5 parts SiC@SiO2-B2O3 nanocrystals, and 1-1.5 parts rare earth pre-melted frit.

9. The method for preparing a thermally shock resistant, high-toughness borosilicate glass according to claim 1, characterized in that: In the glass substrate forming step, the melting process involves: first, heating from room temperature to 800-810℃ at a heating rate of 5-7℃ / min, and holding at that temperature for 60-70min; then heating to 1440-1450℃ at a heating rate of 5-7℃ / min, and holding at that temperature for 60-70min.

10. The method for preparing a thermally shock resistant, high-toughness borosilicate glass according to claim 1, characterized in that: In the step of obtaining the finished glass product, the mass ratio of potassium nitrate, potassium hydroxide and potassium carbonate is (85-90):(3-5):(3-5).

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