Electronic ceramic material based on calcined alpha-Al2O3 and preparation method thereof

Abstract

The invention belongs to the technical field of glass ceramic materials, and particularly relates to an electronic ceramic material based on calcined alpha-Al2O3 and a preparation method thereof. The material comprises the following components in parts by weight: 70 to 80 parts of SiO2, 15 to 20 parts of calcined alpha-Al2O3, 8 to 15 parts of CaO, 0.5 to 5 parts of ZrO2, 1 to 5 parts of ZnO, 0.5 to 2.5 parts of La2O3, 0.5 to 2 parts of Li2O and 0.1 to 1 part of K2O. The mass of ZnO is a, the mass of La2O3 is b, and 1.5 < = a / b < = 2. And ZnO inhibits the formation of large-size crystal grains, so that the size of the separated crystal grains is refined. La2O3 serves as a rare earth element, the atomic radius of La2O3 is smaller than that of cerium, and lattice distortion is not prone to being caused. A proper amount of ZnO and La2O3 can prevent the network structure of the electronic ceramic material from loosening, improve the stability of the electronic ceramic material and reduce the coefficient of thermal expansion.

Description

Technical Field

[0001] The present invention belongs to the technical field of glass-ceramic materials, and particularly relates to an electronic ceramic material based on calcined α-Al2O3 and a preparation method thereof. Background Art

[0002] As a very active member of the material family, electronic ceramic materials play an increasingly important role in broad fields such as networks, communications, and information technology with their superior dielectric properties and physical characteristics; at the current historical stage of scientific development, its status is irreplaceable. For example, computer chips, mobile phone chips, and the physical frameworks of global computer networks and communication networks, etc., all rely on various components made of electronic ceramic materials. If the 21st century is the era of information technology, then electronic ceramic materials are the carriers for carrying these information technologies. Electronic ceramics are essentially different from general industrial ceramics in terms of chemical composition, microstructure, and electromechanical properties. The most important of these are high mechanical strength, resistance to high temperature and humidity, radiation resistance, a small change in the thermal expansion coefficient within a small range, a small value of the dielectric loss tangent, an adjustable temperature coefficient of capacitance (or an adjustable capacitance change rate), high breakdown strength and insulation resistance value, and excellent aging performance. Its manufacturing process is similar to that of general ceramics. After uniformly mixing various ceramic powders, forming, and sintering into porcelain at a certain temperature.

[0003] Electronic ceramics are mainly applied in sensors, luminescent materials, optical waveguide materials, laser materials, electronic components, magnetic recording materials, etc. At present, due to their wide application and great development prospects, electronic ceramics have increasingly become the new favorite in ceramics. Their application scope is rapidly expanding from aspects such as capacitors, filters, igniters, magnetic heads, and communication device components to high-tech fields such as aerospace, aviation, satellites, and semiconductor chips. The structure of electronic ceramics is an aggregate of grains at the microscale. There are grain boundaries between the grains, and a large number of impurity ions and amorphous glassy substances often accumulate at the grain boundaries. When the purity of each phase of powder materials is relatively high, the ratio and sintering temperature are appropriate, and the glass phase is less, we can consider that the ceramic is composed of seamless accumulations of grains of different sizes and shapes. The macroscopic properties of the ceramic are the result of the interaction of these microscopic grains. The interaction mechanism is very complex (such as the composite dielectric polarization mechanism), and some of the mechanism has not been clearly explained so far. This brings great difficulties to the research and preparation of electronic ceramics. So far, most people can only try to find various empirical rules by changing the composition and ratio of the additive phase, and thus obtain the formula of high-performance electronic ceramic materials. This research method with a trial nature is undoubtedly very labor-intensive and material-consuming, with a long cycle and low efficiency. CN119638391A discloses a microwave dielectric ceramic material, which is composed of the following components in parts by mass: 75-95 parts of the first main material, 0-18.4 parts of the second main material, 0.03-3.9 parts of B2O3, and 0-13.5 parts of the remaining components; the first main material is SiO2. Although this glass ceramic improves the problem that the microwave dielectric ceramic material is prone to cracking after sintering, its mechanical strength is low and the expansion coefficient is large, which limits its application scope. Summary of the Invention

[0004] To solve these problems, the present invention provides an electronic ceramic material based on calcined α-Al2O3 and its preparation method, which improves its mechanical strength and reduces its thermal expansion coefficient on this basis to improve the stability of the electronic ceramic material.

[0005] In a first aspect, the present invention provides an electronic ceramic material based on calcined α-Al2O3, which, in parts by weight, comprises the following components: 70-80 parts of SiO2, 15-20 parts of calcined α-Al2O3, 8-15 parts of CaO, 0.5-5 parts of ZrO2, 1-5 parts of ZnO, 0.5-2.5 parts of La2O3, 0.5-2 parts of Li2O, 0.1-1 part of K2O; and the mass of ZnO is a, the mass of La2O3 is b, and 1.5 ≤ a / b ≤ 2.

[0006] Common alumina on the market includes calcined alumina and ordinary industrial alumina. The main phase of calcined alumina is α-Al2O3, which has a dense structure and is stable at high temperatures. The crystal structure of calcined α-Al2O3 is more ordered and the grain size is more uniform, which is beneficial to improving the uniformity and stability of alumina. Calcined α-Al2O3 has high thermal stability and chemical stability, and its hardness, density, thermal conductivity and electrical conductivity have been significantly improved, and it has a wide range of applications in the electronics, construction and machinery industries. The main phase of ordinary industrial alumina is γ-Al2O3, which is unstable and will slowly transform into α-Al2O3 at high temperatures. This is an irreversible phase transformation process, and the particles will agglomerate during the transformation process, resulting in uneven distribution of each phase, thereby reducing the mechanical strength of the product and affecting the final performance of the product. In the present invention, calcined α-Al2O3 is prepared by a mineralizer calcination process, which not only reduces the content of impurities such as sodium element in alumina and improves the purity of alumina, but also avoids the technical problems of uneven phase distribution and reduced mechanical strength caused by γ-Al2O3.

[0007] Adding an appropriate amount of calcined α-Al2O3 to electronic ceramic materials endows the electronic ceramic materials with good mechanical and chemical properties. Compared with other ordinary ceramic materials, it can form an aluminum-oxygen tetrahedron structure and microcrystalline strengthening effect, making it have strong mechanical properties. Calcined α-Al2O3 can improve the heat resistance and corrosion resistance of electronic ceramic materials, making the ceramics more stable. At the same time, calcined α-Al2O3 can improve the hardness and tensile strength of electronic ceramic materials, and the addition of aluminum improves the strength and chemical stability of electronic ceramic materials. And CaO exists in the electronic ceramic components and does not participate in constructing the main network. The outer layer of calcium ions has more electrons and a large radius, and it is not easy to precipitate. Adding a certain amount of CaO can balance the negative charges in the system and reduce the defects in electronic ceramic materials.

[0008] However, the SiO2-Al2O3-CaO electronic ceramic material still has problems of high expansion coefficient and poor thermal stability. To improve the stability of the electronic ceramic material, a certain amount of ZrO2 is added in the present invention. ZrO2 has a large cation charge and a relatively small ionic radius, which can effectively improve the hardness and mechanical properties of the electronic ceramic material. At the same time, ZrO2 is also likely to cause an increase in the viscosity of the electronic ceramic material, which is not conducive to melting processing and is extremely likely to cause an increase in pores and microcracks. The addition of ZnO and La2O3 well solves the problems that may be caused by the addition of ZrO2. ZnO inhibits the formation of large-sized grains, making the precipitated grain size refined. This not only helps to improve the toughness and hardness of the electronic ceramic material, but also improves its denseness, makes its structure more complete, and improves the stability of the electronic ceramic material. As a rare earth element, La2O3 has a smaller atomic radius than cerium and is not likely to cause lattice distortion. An appropriate amount of La2O3 can play an aggregating role, prevent the network structure of the electronic ceramic material from loosening, improve its stability, and reduce the thermal expansion coefficient. The dosages of ZnO and La2O3 should be controlled within a certain range. Otherwise, ZnO and La2O3 may cause network structure distortion, damage the network structure, resulting in a decrease in the integrity of the network in the electronic ceramic material, a loose structure, and an increase in the expansion coefficient.

[0009] Further, by weight, it contains the following components: 72-78 parts of SiO2, 15-19 parts of calcined α-Al2O3, 8-12 parts of CaO, 0.5-3 parts of ZrO2, 1-5 parts of ZnO, 0.5-2.5 parts of La2O3, 0.5-2 parts of Li2O, 0.1-0.5 parts of K2O; and the mass of ZnO is a, the mass of La2O3 is b, and 1.5 ≤ a / b ≤ 2. ZrO2 can improve the mechanical properties of the electronic ceramic material, but its ionic radius is large, which is likely to cause the glass structure to be loose and reduce the binding ability to ions. The higher the temperature, the larger the movement amplitude of the proton points in the glass ceramic, the increase in the distance between the particles, and thus the increase in the thermal expansion coefficient, resulting in the instability of the system.

[0010] Furthermore, by weight parts, it contains the following components: 72.5 - 77.5 parts of SiO₂, 15.5 - 18 parts of calcined α-Al₂O₃, 8.5 - 11 parts of CaO, 1 - 3 parts of ZrO₂, 1 - 5 parts of ZnO, 0.5 - 2.5 parts of La₂O₃, 0.5 - 2 parts of Li₂O, 0.1 - 0.5 parts of K₂O, and the mass of ZnO is a, the mass of La₂O₃ is b, and 1.5 ≤ a / b ≤ 2. The effects of mixed alkali metals and alkaline earth metals show the non-linear relationship between the ratios of different alkali metal ions and the structure and properties of the electronic ceramic material, and vary with the sizes and dosages of alkali metals and alkaline earth metal ions. When an appropriate amount of alkaline earth metal cations are introduced into the electronic ceramic material, it will generate a higher activation energy and reduce the ion mobility, which will improve the network rigidity of the electronic ceramic material, reduce the plastic flow, and thus increase the mechanical properties and chemical stability of the electronic ceramic material.

[0011] On the other hand, the present invention also provides a preparation method of an electronic ceramic material based on calcined α-Al₂O₃, including the following steps: Weigh the raw materials, mix the raw materials evenly to obtain a mixture. Melt the mixture to prepare a molten liquid. Pour the molten liquid into a mold for molding, and after annealing, obtain the electronic ceramic material based on calcined α-Al₂O₃. Furthermore, the preparation process of the calcined α-Al₂O₃ is as follows: After grinding, screening, and impurity removal of industrial γ-Al₂O₃, add a mineralizer, mix evenly, and obtain calcined α-Al₂O₃ after high-temperature calcination and cooling.

[0012] Furthermore, the mineralizer is at least one of boric acid and ammonium salts, and its mass is 0.2 - 1 wt% of industrial γ-Al₂O₃; the calcination temperature is 1300 - 1400 °C, and the calcination time is 3 - 4 h.

[0013] Furthermore, the raw materials are mixed by grinding.

[0014] Furthermore, the melting temperature of the mixture is 1500 - 1700 °C, and the time is 4 - 5 h.

[0015] Furthermore, the mold is a steel plate mold, a cast iron mold, or a graphite mold; the annealing process is carried out in a muffle furnace or a box-type resistance furnace.

[0016] Further, the annealing temperature is 640 - 720 °C and the time is 1 - 3 h. By adjusting the electronic ceramic material formula and the melting and heat treatment processes, the types of crystal phases precipitated, the crystallinity, and the grain size in the structure of the electronic ceramic material can be controlled, and a ceramic material with a large number of nanoscale grains can be prepared, and excellent electronic ceramic products with high strength and stable dimensions can be obtained.

[0017] Beneficial effects: Adding an appropriate amount of calcined α-Al2O3 to the electronic ceramic material endows the electronic ceramic material with good mechanical and chemical properties. Compared with other ordinary ceramic materials, the formation of an aluminum-oxygen tetrahedron structure and the microcrystalline strengthening effect endow it with strong mechanical properties. ZrO2 has a large cation charge and a small ionic radius, which can effectively improve the hardness and mechanical properties of the electronic ceramic material. ZnO inhibits the formation of large-sized grains, resulting in the refinement of the precipitated grain size, which not only helps to improve the toughness and hardness of the electronic ceramic material, but also improves its densification, makes its structure more complete, and improves the stability of the electronic ceramic material. As a rare earth element, La2O3 has a smaller atomic radius than cerium and is not easily prone to lattice distortion. An appropriate amount of La2O3 can play an accumulation role, prevent the relaxation of the network structure of the electronic ceramic material, improve its stability, reduce the thermal expansion coefficient, and make the electronic ceramic material particularly suitable for the production of large electrical components. Specific embodiments

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0019] Example 1 An electronic ceramic material based on calcined α-Al2O3, in parts by weight, comprises the following components: 70 parts of SiO2, 15 parts of calcined α-Al2O3, 8 parts of CaO, 1 part of ZrO2, 1 part of ZnO, 0.5 part of La2O3, 0.5 part of Li2O, 0.1 part of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b = 2.00.

[0020] The preparation method of the electronic ceramic material comprises the following steps: Weigh each raw material and grind each raw material evenly to obtain a mixture; Melt the mixture to prepare a melt; the melting temperature of the mixture is 1550 °C and the time is 5 h; Pour the molten liquid into a graphite mold for forming, and obtain an electronic ceramic material based on calcined α-Al2O3 after annealing in a muffle furnace; the annealing temperature is 640 °C and the time is 3 h; Among them, the preparation process of the calcined α-Al2O3 is as follows: After grinding, screening, and impurity removal of industrial γ-Al2O3, boric acid is added, and after mixing evenly, calcined α-Al2O3 is obtained through high-temperature calcination and cooling; the mass of boric acid is 0.5 wt% of industrial γ-Al2O3; the calcination temperature is 1370 °C and the calcination time is 3.4 h.

[0021] Example 2 An electronic ceramic material based on calcined α-Al2O3, by weight, contains the following components: 80 parts of SiO2, 20 parts of calcined α-Al2O3, 11 parts of CaO, 3 parts of ZrO2, 5 parts of ZnO, 2.5 parts of La2O3, 2 parts of Li2O, 1 part of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b = 2.00.

[0022] The preparation method of the electronic ceramic material includes the following steps: Weigh each raw material and grind each raw material evenly to obtain a mixed material; Melt the mixed material to prepare a molten liquid; the melting temperature of the mixed material is 1650 °C and the time is 4 h; Pour the molten liquid into a graphite mold for forming, and obtain an electronic ceramic material based on calcined α-Al2O3 after annealing in a muffle furnace; the annealing temperature is 720 °C and the time is 1.5 h; Among them, the preparation process of the calcined α-Al2O3 is as follows: After grinding, screening, and impurity removal of industrial γ-Al2O3, boric acid is added, and after mixing evenly, calcined α-Al2O3 is obtained through high-temperature calcination and cooling; the mass of boric acid is 0.5 wt% of industrial γ-Al2O3; the calcination temperature is 1370 °C and the calcination time is 3.4 h.

[0023] Example 3 An electronic ceramic material based on calcined α-Al2O3, by weight, contains the following components: 80 parts of SiO2, 15 parts of calcined α-Al2O3, 11 parts of CaO, 1 part of ZrO2, 1.5 parts of ZnO, 1 part of La2O3, 2 parts of Li2O, 0.3 part of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b = 1.50.

[0024] The preparation method of the electronic ceramic material includes the following steps: Weigh each raw material and grind each raw material evenly to obtain a mixed material; Melt the mixture to prepare a molten liquid; the melting temperature of the mixture is 1580 °C and the time is 4.7 h; Pour the molten liquid into a graphite mold for shaping, and obtain an electronic ceramic material based on calcined α-Al2O3 after annealing in a muffle furnace; the annealing temperature is 650 °C and the time is 2.6 h; Among them, the preparation process of the calcined α-Al2O3 is as follows: After grinding, screening, and impurity removal of industrial γ-Al2O3, boric acid is added, and after mixing evenly, calcined α-Al2O3 is obtained after high-temperature calcination and cooling; the mass of boric acid is 0.5 wt% of industrial γ-Al2O3; the calcination temperature is 1370 °C and the calcination time is 3.4 h.

[0025] Example 4 An electronic ceramic material based on calcined α-Al2O3, by weight, contains the following components: 73 parts of SiO2, 16 parts of calcined α-Al2O3, 9 parts of CaO, 1.5 parts of ZrO2, 3.2 parts of ZnO, 2 parts of La2O3, 1.6 parts of Li2O, 0.8 part of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b = 1.60.

[0026] The preparation method of the electronic ceramic material includes the following steps: Weigh each raw material and grind each raw material evenly to obtain a mixture; Melt the mixture to prepare a molten liquid; the melting temperature of the mixture is 1620 °C and the time is 4.2 h; Pour the molten liquid into a graphite mold for shaping, and obtain an electronic ceramic material based on calcined α-Al2O3 after annealing in a muffle furnace; the annealing temperature is 680 °C and the time is 2.3 h; Among them, the preparation process of the calcined α-Al2O3 is as follows: After grinding, screening, and impurity removal of industrial γ-Al2O3, boric acid is added, and after mixing evenly, calcined α-Al2O3 is obtained after high-temperature calcination and cooling; the mass of boric acid is 0.5 wt% of industrial γ-Al2O3; the calcination temperature is 1370 °C and the calcination time is 3.4 h.

[0027] Example 5 An electronic ceramic material based on calcined α-Al2O3, by weight, contains the following components: 78 parts of SiO2, 18 parts of calcined α-Al2O3, 10.4 parts of CaO, 2.4 parts of ZrO2, 2.1 parts of ZnO, 1.1 parts of La2O3, 1.3 parts of Li2O, 0.3 part of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b = 1.91.

[0028] A preparation method of electronic ceramic materials, comprising the following steps: Weigh each raw material, grind each raw material evenly to obtain a mixed material; Melt the mixed material to prepare a molten liquid; the melting temperature of the mixed material is 1590 °C and the time is 4.7 h; Pour the molten liquid into a graphite mold for forming, and obtain an electronic ceramic material based on calcined α-Al2O3 after annealing in a muffle furnace; the annealing temperature is 660 °C and the time is 2.2 h; Among them, the preparation process of the calcined α-Al2O3 is as follows: After grinding, screening and impurity removal of industrial γ-Al2O3, boric acid is added, mixed evenly, and calcined α-Al2O3 is obtained after high-temperature calcination and cooling; the mass of boric acid is 0.5 wt% of industrial γ-Al2O3; the calcination temperature is 1370 °C and the calcination time is 3.4 h.

[0029] Example 6 An electronic ceramic material based on calcined α-Al2O3, in parts by weight, comprises the following components: 76 parts of SiO2, 16.5 parts of calcined α-Al2O3, 10 parts of CaO, 0.5 part of ZrO2, 2.7 parts of ZnO, 1.5 parts of La2O3, 1.6 parts of Li2O, 0.6 part of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b = 1.80.

[0030] A preparation method of electronic ceramic materials, comprising the following steps: Weigh each raw material, grind each raw material evenly to obtain a mixed material; Melt the mixed material to prepare a molten liquid; the melting temperature of the mixed material is 1600 °C and the time is 4.1 h; Pour the molten liquid into a graphite mold for forming, and obtain an electronic ceramic material based on calcined α-Al2O3 after annealing in a muffle furnace; the annealing temperature is 690 °C and the time is 2.2 h; Among them, the preparation process of the calcined α-Al2O3 is as follows: After grinding, screening and impurity removal of industrial γ-Al2O3, boric acid is added, mixed evenly, and calcined α-Al2O3 is obtained after high-temperature calcination and cooling; the mass of boric acid is 0.5 wt% of industrial γ-Al2O3; the calcination temperature is 1370 °C and the calcination time is 3.4 h.

[0031] Example 7 An electronic ceramic material based on calcined α-Al2O3, in parts by weight, comprises the following components: 76 parts of SiO2, 17.4 parts of calcined α-Al2O3, 9.6 parts of CaO, 2.3 parts of ZrO2, 3 parts of ZnO, 1.6 parts of La2O3, 1.7 parts of Li2O, 0.3 parts of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b = 1.88.

[0032] A preparation method of an electronic ceramic material, comprising the following steps: Weigh each raw material, grind each raw material evenly to obtain a mixed material; Melt the mixed material to prepare a molten liquid; the melting temperature of the mixed material is 1590 °C and the time is 4.6 h; Pour the molten liquid into a graphite mold for molding, and obtain an electronic ceramic material based on calcined α-Al2O3 after annealing in a muffle furnace; the annealing temperature is 690 °C and the time is 2.7 h; Among them, the preparation process of the calcined α-Al2O3 is as follows: After grinding, screening and impurity removal of industrial γ-Al2O3, boric acid is added, mixed evenly, and calcined at high temperature and cooled to obtain calcined α-Al2O3; the mass of boric acid is 0.5 wt% of industrial γ-Al2O3; the calcination temperature is 1370 °C and the calcination time is 3.4 h.

[0033] Example 8 An electronic ceramic material based on calcined α-Al2O3, in parts by weight, comprises the following components: 76 parts of SiO2, 16.5 parts of calcined α-Al2O3, 10 parts of CaO, 5 parts of ZrO2, 2.7 parts of ZnO, 1.5 parts of La2O3, 1.6 parts of Li2O, 0.6 parts of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b = 1.80.

[0034] A preparation method of an electronic ceramic material, comprising the following steps: Weigh each raw material, grind each raw material evenly to obtain a mixed material; Melt the mixed material to prepare a molten liquid; the melting temperature of the mixed material is 1600 °C and the time is 4.1 h; Pour the molten liquid into a graphite mold for molding, and obtain an electronic ceramic material based on calcined α-Al2O3 after annealing in a muffle furnace; the annealing temperature is 690 °C and the time is 2.2 h; Among them, the preparation process of the calcined α-Al2O3 is as follows: After grinding, screening and impurity removal of industrial γ-Al2O3, boric acid is added, mixed evenly, and calcined at high temperature and cooled to obtain calcined α-Al2O3; the mass of boric acid is 0.5 wt% of industrial γ-Al2O3; the calcination temperature is 1370 °C and the calcination time is 3.4 h.

[0035] Example 9 An electronic ceramic material based on calcined α-Al2O3, by weight, contains the following components: 71 parts of SiO2, 17.2 parts of calcined α-Al2O3, 9.8 parts of CaO, 2.3 parts of ZrO2, 1.4 parts of ZnO, 0.9 part of La2O3, 1.3 parts of Li2O, 0.4 part of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b = 1.56.

[0036] The preparation method of the electronic ceramic material includes the following steps: Weigh each raw material, grind each raw material evenly to obtain a mixed material; Melt the mixed material to prepare a molten liquid; the melting temperature of the mixed material is 1580 °C and the time is 4.7 h; Pour the molten liquid into a graphite mold for molding, and obtain an electronic ceramic material based on calcined α-Al2O3 after annealing in a muffle furnace; the annealing temperature is 690 °C and the time is 1.9 h; Among them, the preparation process of the calcined α-Al2O3 is as follows: After grinding, screening, and impurity removal of industrial γ-Al2O3, boric acid is added, mixed evenly, and calcined at high temperature and cooled to obtain calcined α-Al2O3; the mass of boric acid is 0.5 wt% of industrial γ-Al2O3; the calcination temperature is 1370 °C and the calcination time is 3.4 h.

[0037] Example 10 An electronic ceramic material based on calcined α-Al2O3, by weight, contains the following components: 76 parts of SiO2, 16.5 parts of calcined α-Al2O3, 15 parts of CaO, 2 parts of ZrO2, 2.7 parts of ZnO, 1.5 parts of La2O3, 1.6 parts of Li2O, 0.6 part of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b = 1.80.

[0038] The preparation method of the electronic ceramic material includes the following steps: Weigh each raw material, grind each raw material evenly to obtain a mixed material; Melt the mixed material to prepare a molten liquid; the melting temperature of the mixed material is 1600 °C and the time is 4.1 h; Pour the molten liquid into a graphite mold for molding, and obtain an electronic ceramic material based on calcined α-Al2O3 after annealing in a muffle furnace; the annealing temperature is 690 °C and the time is 2.2 h; Among them, the preparation process of the calcined α-Al2O3 is as follows: After grinding, screening, and impurity removal of industrial γ-Al2O3, boric acid is added, and the mixture is uniformly mixed. After high-temperature calcination and cooling, calcined α-Al2O3 is obtained; the mass of boric acid is 0.5 wt% of industrial γ-Al2O3; the calcination temperature is 1370 °C, and the calcination time is 3.4 h.

[0039] Example 11 An electronic ceramic material based on calcined α-Al2O3, by weight, comprises the following components: 75.5 parts of SiO2, 15.8 parts of calcined α-Al2O3, 9.5 parts of CaO, 2.6 parts of ZrO2, 3.9 parts of ZnO, 2.4 parts of La2O3, 0.8 part of Li2O, 0.2 part of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b = 1.63.

[0040] The preparation method of the electronic ceramic material comprises the following steps: Weigh each raw material, grind each raw material evenly to obtain a mixed material; Melt the mixed material to prepare a molten liquid; the melting temperature of the mixed material is 1560 °C, and the time is 4.9 h; Pour the molten liquid into a graphite mold for molding, and after annealing in a muffle furnace, an electronic ceramic material based on calcined α-Al2O3 is obtained; the annealing temperature is 710 °C, and the time is 1.5 h; Among them, the preparation process of the calcined α-Al2O3 is as follows: After grinding, screening, and impurity removal of industrial γ-Al2O3, boric acid is added, and the mixture is uniformly mixed. After high-temperature calcination and cooling, calcined α-Al2O3 is obtained; the mass of boric acid is 0.5 wt% of industrial γ-Al2O3; the calcination temperature is 1370 °C, and the calcination time is 3.4 h.

[0041] Example 12 An electronic ceramic material based on calcined α-Al2O3, by weight, comprises the following components: 76 parts of SiO2, 16.5 parts of calcined α-Al2O3, 10 parts of CaO, 2 parts of ZrO2, 2.7 parts of ZnO, 1.5 parts of La2O3, 1.6 parts of Li2O, 0.6 part of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b = 1.80.

[0042] The preparation method of the electronic ceramic material comprises the following steps: Weigh each raw material, grind each raw material evenly to obtain a mixed material; Melt the mixed material to prepare a molten liquid; the melting temperature of the mixed material is 1600 °C, and the time is 4.1 h; Pour the molten liquid into a graphite mold for shaping, and obtain an electronic ceramic material based on calcined α-Al2O3 after annealing in a muffle furnace; the annealing temperature is 690 °C and the time is 2.2 h; Among them, the preparation process of the calcined α-Al2O3 is as follows: After grinding, screening, and impurity removal of industrial γ-Al2O3, boric acid is added, mixed evenly, and calcined at high temperature and cooled to obtain calcined α-Al2O3; the mass of boric acid is 0.5 wt% of industrial γ-Al2O3; the calcination temperature is 1370 °C and the calcination time is 3.4 h.

[0043] Comparative Example 1 Its components and raw materials are basically the same as those in Example 12, except that: 2 parts of ZnO, 2 parts of La2O3; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b = 1.

[0044] Comparative Example 2 Its components and raw materials are basically the same as those in Example 12, except that: 2.3 parts of ZnO, 1 part of La2O3; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b = 2.30.

[0045] Performance test: Prepare the electronic ceramic materials based on calcined α-Al2O3 prepared in the examples and comparative examples into standard specimens, and test their flexural strength (GB / T6569-2006), Vickers hardness (ASTM E-384), and coefficient of thermal expansion (50-350 °C, ASTM E-228) according to the three-point bending method. The results are shown in Tables 1-2.

[0046] Table 1 Performance of the electronic ceramic materials based on calcined α-Al2O3 prepared in Examples 1-7 Table 2 Performance of the electronic ceramic materials based on calcined α-Al2O3 prepared in Examples 8-12 and Comparative Examples 1-2 As can be seen from Table 1 - Table 2, ZrO2 has a large cation charge and a relatively small ionic radius, which can effectively improve the hardness and mechanical properties of electronic ceramic materials. At the same time, ZrO2 is also likely to increase the viscosity of electronic ceramic materials, which is not conducive to melting processing and is extremely likely to cause an increase in pores and microcracks. The addition of ZnO and La2O3 has well solved the problems that may be caused by the addition of ZrO2. ZnO inhibits the formation of large-sized grains, making the precipitated grain size refined. This not only helps to improve the strength and hardness of electronic ceramic materials, but also improves their densification, makes their structure more complete, and improves the stability of electronic ceramic materials. As a rare earth element, La2O3 has a smaller atomic radius than cerium and is not likely to cause lattice distortion. An appropriate amount of La2O3 can play an aggregating role, prevent the network structure of electronic ceramic materials from relaxing, improve their stability, and reduce the thermal expansion coefficient.

[0047] Compared with Example 12, the dosages of ZnO and La2O3 in Comparative Example 1 and Comparative Example 2 were not controlled within a certain range, which would lead to network structure distortion, damage the network structure, reduce the integrity of the network in electronic ceramic materials, make the structure loose, and increase the expansion coefficient.

[0048] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as these combinations of technical features do not conflict, they should all be considered as the scope described in this specification.

[0049] The above-described embodiments only represent several implementation manners of the present invention. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims, and the specification can be used to explain the content of the claims.

Claims

1. An electronic ceramic material based on calcined α-Al2O3, characterized in that, Comprising the following components by weight parts: 70 - 80 parts of SiO2, 15 - 20 parts of calcined α - Al2O3, 8 - 15 parts of CaO, 0.5 - 5 parts of ZrO2, 1 - 5 parts of ZnO, 0.5 - 2.5 parts of La2O3, 0.5 - 2 parts of Li2O, 0.1 - 1 part of K2O; and the mass of ZnO is a, the mass of La2O3 is b, and 1.5 ≤ a / b ≤ 2.

2. The electronic ceramic material based on calcined α-Al2O3 according to claim 1, wherein Comprising the following components by weight parts: 72.5 - 77.5 parts of SiO2, 15.5 - 18 parts of calcined α - Al2O3, 8.5 - 11 parts of CaO, 1 - 3 parts of ZrO2, 1 - 5 parts of ZnO, 0.5 - 2.5 parts of La2O3, 0.5 - 2 parts of Li2O, 0.1 - 0.5 part of K2O, and the mass of ZnO is a, the mass of La2O3 is b, and 1.5 ≤ a / b ≤ 2.

3. The preparation method of an electronic ceramic material based on calcined α-Al2O3 according to claim 1, characterized in that, Including the following steps: Weigh the raw materials according to the components described in Claim 1, and mix the raw materials evenly to obtain a mixed material. Melt the mixed material to prepare a molten liquid. Pour the molten liquid into a mold for shaping, and after annealing, obtain an electronic ceramic material based on calcined α - Al2O3.

4. The preparation method of an electronic ceramic material based on calcined α-Al2O3 according to claim 3, characterized in that, The preparation process of the calcined α - Al2O3 is as follows: After grinding, screening, and impurity removal of industrial γ - Al2O3, add a mineralizer, mix evenly, and obtain calcined α - Al2O3 after high - temperature calcination and cooling.

5. The preparation method of an electronic ceramic material based on calcined α-Al2O3 according to claim 4, characterized in that, The mineralizer is at least one of boric acid and ammonium salt, and its mass is 0.2 - 1 wt% of industrial γ - Al2O3; the calcination temperature is 1300 - 1400 °C, and the calcination time is 3 - 4 h.

6. The preparation method of an electronic ceramic material based on calcined α-Al2O3 according to claim 3, characterized in that, Mix the raw materials by grinding.

7. The preparation method of an electronic ceramic material as described in claim 3, characterized in that, The melting temperature of the mixed material is 1500 - 1700 °C, and the time is 4 - 5 h.

8. The preparation method of an electronic ceramic material based on calcined α-Al2O3 according to claim 3, characterized in that, The mold is a steel plate mold, a cast iron mold, or a graphite mold; the annealing process is carried out in a muffle furnace or a box - type resistance furnace.

9. The preparation method of an electronic ceramic material based on calcined α-Al2O3 according to claim 3, characterized in that, The annealing temperature is 640 - 720 °C, and the time is 1 - 3 h.

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