Method for preparing microcrystalline glass in air atmosphere

Abstract

The invention discloses a method for preparing microcrystalline glass in an air atmosphere, and belongs to the technical field of ceramic products. The invention aims to provide a method for preparing microcrystalline glass in an air atmosphere, which adopts a material taking silicon nitride as a main component as a material of a pressure body (1), and metal tungsten is arranged in the pressure body (1) as a heating body (3). The characteristics of high heat conductivity, high strength, oxidation resistance and high temperature resistance of the silicon nitride material are exerted, the dependence on inert air atmosphere in the original microcrystalline glass preparation process is overcome, the requirement on equipment is reduced, the production process for preparing the microcrystalline glass by a rolling method is simplified, the service life of various tools is prolonged, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic products, and particularly to a method for preparing glass-ceramics in an air atmosphere. Background Art

[0002] In the existing process of preparing glass-ceramics, it is necessary to heat the glass-ceramics to 1500 °C to melt them into a liquid, and then perform calendering and forming in an environment of 1100 °C. Graphite has the characteristics of high temperature resistance, corrosion resistance, high thermal conductivity, and self-lubrication, and is the preferred material for the pressing plate in an environment of 1100 °C. However, in a high-temperature process environment, it is necessary to carry out the process in a sealed, inert gas atmosphere environment to ensure that the graphite pressing plate is not oxidized.

[0003] The existing technology provides a sealed chamber filled with nitrogen or argon, heats the sealed chamber at a high temperature and uses a graphite pressing plate for calendering and forming. In this technology, when feeding the glass-ceramic material and its carrier into the sealed chamber, it requires a complex process of removing oxygen and filling inert gas, and the graphite has low strength and is prone to wear.

[0004] The present invention provides a new method for preparing glass-ceramics, which does not require a specific inert gas atmosphere, simplifies the equipment, reduces equipment investment, and improves efficiency. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing glass-ceramics in an air atmosphere. The present invention uses a silicon nitride material as the die pressing cover plate material, and a metal tungsten is built into the die pressing cover as a heating element. By changing the material of the die pressing cover, the present invention overcomes the drawback that the material is oxidized in a high-temperature environment, reduces the requirements for equipment, and shortens the process flow.

[0006] A method for preparing glass-ceramics in an air atmosphere, characterized in that its steps are as follows: S1. Mix the raw materials to obtain a mixed material.

[0007] S2. Put the mixed material into a carrier and melt it at 1400 °C to 1500 °C to obtain a glass-ceramic liquid.

[0008] S3. Prepare a new die pressing cover. The new die pressing cover is divided into a pressure body (1) and a heating body (3). The mass component ratio of silicon nitride in the pressure body (1) is more than 80%. The material of the heating body (3) is tungsten. The pressure body (1) needs to have high strength, high hardness, high temperature resistance, high lubricity, high thermal conductivity, and sealing properties. The pressure body (1) mainly composed of silicon nitride has the above properties, and the pressure-applying surface of the pressure body (1) is a smooth and flat structure. The heating body (3) is made of metal tungsten, and metal tungsten has the characteristic of high temperature resistance and is a good electric heating wire material.

[0009] S4. Electrify the new type of molded cover plate for heating until the temperature of the pressing surface of the new type of molded cover plate reaches 1000°C - 1200°C.

[0010] S5. Under the natural air atmosphere, use the heated new type of molded cover plate to roll and form the glass liquid to make a semi-finished microcrystalline glass sheet.

[0011] S6. Perform crystallization treatment on the semi-finished microcrystalline glass sheet, and then perform annealing treatment to obtain microcrystalline glass.

[0012] Further, the mixture in step S1 is composed of one or two or three or four combinations of quartz sand, sodium carbonate, calcite, alumina, and titanium oxide.

[0013] Further, the melting time of the mixture in step S2 is 24 - 32 h.

[0014] Further, the carrier in step S2 is sintered after being molded by pressing a mixed powder of Si3N4 powder, AlN, Y2O3, MgO, Li2O, La2O3, and a sintering aid. The mass fraction ratio of Si3N4 powder, AlN, Y2O3, MgO, Li2O, La2O3, and the sintering aid is (80 - 92):(2 - 7):(2 - 7):(1 - 5):(1 - 5):(1 - 5):(1 - 3).

[0015] Further, the pressure body (1) in step S3 is sintered after being molded by pressing a mixed powder of Si3N4 powder, AlN, Y2O3, MgO, Li2O, La2O3, and a sintering aid. The mass fraction ratio of Si3N4 powder, AlN, Y2O3, MgO, Li2O, La2O3, and the sintering aid is (80 - 92):(2 - 7):(2 - 7):(1 - 5):(1 - 5):(1 - 5):(1 - 3).

[0016] Further, the heating body (3) in step S3 is completely covered by the pressure body (1) to isolate oxygen oxidation.

[0017] Further, the natural air atmosphere in step S5 is an air environment that does not require excluding oxygen interference. Description of the Drawings

[0018] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art.

[0019] Figure 1 It is a preparation scenario diagram of the old process: vacuum chamber (8), microcrystalline glass carrier (7), graphite pressing plate (9), sealing chamber (11); Figure 2Preparation scenario diagram under the process of the present invention: silicon nitride pressing plate (6), heat preservation cover (5), silicon nitride carrier (4). Figure 3 Structural diagram of the silicon nitride pressing plate: pressure body (1), electrode (2), heating body (3). Specific implementation manners

[0020] The following embodiments are provided to better further understand the present invention, which are not limited to the best implementation manner, and do not constitute a limitation to the content and protection scope of the present invention. Any product obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with those of other prior arts and being the same as or similar to the present invention falls within the protection scope of the present invention.

[0021] Embodiment 1: Old process As Figure 1 shown, vacuum chamber (8), glass-ceramic carrier (7), graphite pressing plate (9), sealing chamber (11).

[0022] Place the required amount of glass-ceramic mixed powder on the left glass-ceramic carrier (7). Open the left door of the left vacuum chamber (8), send the glass-ceramic and the carrier into the vacuum chamber (8), close the left door of the left vacuum chamber (8), evacuate the air in the left vacuum chamber (8), open the right door of the left vacuum chamber (8), and send the glass-ceramic and the carrier into the sealing chamber (11) and place them under the graphite pressing plate (9).

[0023] Introduce nitrogen into the sealing chamber (11), heat the glass-ceramic and the carrier to 1500 °C, keep it warm for 26 hours, then slowly cool the temperature of the whole sealing chamber (11) to 1150 °C, and press down the graphite pressing plate (9) to perform rolling forming on the glass-ceramic.

[0024] After rolling forming, the temperature program of the sealing chamber (11) is set to keep it warm at 650 °C for 2 h, to 700 °C for 1 h, 750 °C for 2 h, 800 °C for 1 h, 850 °C for 1 h, and 900 °C for 1 h.

[0025] Then perform annealing treatment to obtain the glass-ceramic.

[0026] Embodiment 2: Process of the present invention As Figure 2 shown, it includes a silicon nitride pressing plate (6), a heat preservation cover (5), and a silicon nitride carrier (4).

[0027] Place the required amount of glass-ceramic mixed powder on the silicon nitride carrier (4), cover it with the heat preservation cover (5). The heat preservation cover (5) does not need to exclude oxygen interference. Heat the silicon nitride carrier (4) to 1500 °C and keep it warm for 26 hours. During the heat preservation period, heat the silicon nitride pressing plate (6) to 1150 °C, press down the silicon nitride pressing plate (6), conduct heat transfer and heat preservation on the glass-ceramic and carry out calendering forming.

[0028] After calendering forming, the silicon nitride pressing plate (6) always remains in contact with the glass-ceramic. Its temperature program is set to keep warm at 650 °C for 2.5 h, to 700 °C for 1.5 h, 750 °C for 2.5 h, 800 °C for 1.5 h, 850 °C for 1.5 h, and 900 °C for 1.5 h.

[0029] Then carry out annealing treatment to obtain the glass-ceramic.

Claims

1. A method for preparing glass-ceramics in air atmosphere, characterized in that: The steps are: S1, mixing raw materials to obtain a mixed material; S2, melting the mixture at 1400° C. to 1500° C. to obtain a glass-ceramic liquid; S3, preparing a new type of molded cover plate, wherein the new type of molded cover plate is divided into a pressure body (1) and a heating body (3), wherein the pressure body (1) has a silicon nitride mass content of more than 80%, and the heating body (3) is made of tungsten; S4, heating the new molded cover plate by powering on, until the temperature of the pressure surface of the new molded cover plate reaches 1000°C-1200°C; S5. In a natural air atmosphere, the glass liquid is pressed and formed using a heated new type molded cover plate to produce a semi-finished microcrystalline glass plate; S6. Perform crystallization treatment on the semi-finished microcrystalline glass plate, and then perform annealing treatment to obtain microcrystalline glass.

2. The method for preparing glass-ceramics in air atmosphere according to claim 1, characterized in that: Step S1: the mixture is composed of one, two, three or four of quartz sand, sodium carbonate, calcite, aluminum oxide and titanium oxide.

3. The method for preparing glass-ceramics in air atmosphere according to claim 1, characterized in that: The melting time of the mixed material in step S2 is 24-32 hours.

4. The method for preparing glass-ceramics in air atmosphere according to claim 1, characterized in that: In step S3, the pressure body (1) is formed by compression molding a mixed powder of Si3N4 powder, AlN, Y2O3, MgO, Li2O, La2O3 and a sintering aid, and the mass fraction ratio of Si3N4 powder, AlN, Y2O3, MgO, Li2O, La2O3 and the sintering aid is (80-92): (2-7): (2-7): (1-5): (1-5): (1-5): (1-3).

5. The method for preparing glass-ceramics in air atmosphere according to claim 1, characterized in that: In step S3, the heating body (3) is completely covered by the pressure body (1) to isolate it from oxygen oxidation.

6. The method for preparing glass-ceramics in air atmosphere according to claim 1, characterized in that: The natural air atmosphere in step S5 is an air environment that does not require the elimination of oxygen interference.

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