An electronic ceramic material based on calcined α-Al2O3 and its preparation method

Abstract

The present invention belongs to the technical field of glass ceramic materials, and in particular relates to an electronic ceramic material based on calcined α-Al2O3 and a preparation method thereof. The material comprises 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, and 0.1-1 parts of K2O; and the mass of ZnO is a, the mass of La2O3 is b, and 1.5≤a / b≤2. ZnO inhibits the formation of large-sized grains and causes the size of the precipitated grains to be refined. As a rare earth element, La2O3 has a smaller atomic radius than cerium and is not prone to lattice distortion. An appropriate amount of ZnO and La2O3 can prevent the network structure of the electronic ceramic material from relaxing, improve its stability, and reduce the thermal expansion coefficient.

Description

Technical Field

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

[0002] As a highly active member of the material family, electronic ceramics, with their superior dielectric and physical properties, are playing an increasingly important role in a wide range of fields, including networking, communications, and information technology. Their position is irreplaceable in the current historical period of scientific development. For example, computer chips, mobile phone chips, and the physical architecture of global computer and communications networks all rely on components made from electronic ceramics. If the 21st century is the era of information technology, then electronic ceramics are the carriers of this information technology. Electronic ceramics differ fundamentally from conventional industrial ceramics in their chemical composition, microstructure, and electromechanical properties. Key requirements include high mechanical strength, resistance to high temperatures and humidity, radiation resistance, a narrow range of thermal expansion coefficients, a low dielectric loss tangent, adjustable capacitance temperature coefficient (or capacitance change rate), high dielectric strength and insulation resistance, and excellent aging performance. The manufacturing process is similar to that of conventional ceramics: uniform mixing of various ceramic powder phases, forming a shape, and then sintering at a specific temperature to form a porcelain.

[0003] Electronic ceramics are primarily used in sensors, luminescent materials, photoconductive materials, laser materials, electronic components, and magnetic recording materials. Currently, electronic ceramics are becoming a rising star among ceramics due to their wide range of applications and enormous development prospects. Their applications are rapidly expanding from capacitors, filters, igniters, magnetic heads, and communication components to high-tech fields such as aerospace, aviation, satellites, and semiconductor chips. On a microscopic scale, the structure of electronic ceramics is an aggregation of individual grains. Grain boundaries exist between the grains, where large amounts of impurity ions and amorphous glassy matter often accumulate. When the powders of each phase are of high purity, the mixing ratio and sintering temperature are appropriate, and the glass phase is relatively low, the ceramic can be considered to be composed of a seamless stack of grains of varying sizes and shapes. The macroscopic properties of ceramics are the result of the interactions between these small microscopic grains. The mechanisms of these interactions are complex (such as the polarization mechanism of composite dielectrics), and some mechanisms remain unclear. This has brought great difficulties to the research and preparation of electronic ceramics, so that to date, most people have been able to only obtain the formula of high-performance electronic ceramic materials by constantly experimenting with the composition and ratio of the added phases, looking for various empirical rules. This experimental research method is undoubtedly very labor-intensive and resource-intensive, with a long cycle and low efficiency. CN119638391A discloses a microwave dielectric ceramic material composed of the following components by weight: 75-95 parts of a first main ingredient, 0-18.4 parts of a second main ingredient, 0.03-3.9 parts of B2O3, and 0-13.5 parts of the remaining components; the first main ingredient is SiO2. Although this glass-ceramic improves the problem of microwave dielectric ceramic materials being prone to cracking after sintering, its low mechanical strength and large expansion coefficient limit its scope of application. Summary of the Invention

[0004] In order to solve these problems, the present invention provides an electronic ceramic material based on calcined α-Al2O3 and a preparation method thereof, which reduces its thermal expansion coefficient while improving its mechanical strength, thereby improving 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, comprising the following components in parts by weight:

[0006] SiO2 70-80 parts, calcined α-Al2O3 15-20 parts, CaO 8-15 parts, ZrO2 0.5-5 parts, ZnO 1-5 parts, La2O3 0.5-2.5 parts, Li2O 0.5-2 parts, K2O 0.1-1 parts; and the mass of ZnO is a, the mass of La2O3 is b, 1.5≤a / b≤2.

[0007] Common aluminas on the market include calcined alumina and standard industrial alumina. Calcined alumina's main phase is α-Al2O3, which has a dense structure and is stable at high temperatures. Calcined α-Al2O3 has a more ordered crystal structure and a more uniform grain size, which helps improve the uniformity and stability of the alumina. Calcined α-Al2O3 also has higher thermal and chemical stability, significantly improving hardness, density, thermal conductivity, and electrical conductivity, and is widely used in industries such as electronics, construction, and machinery. Standard industrial alumina, on the other hand, has a main phase of γ-Al2O3, which is unstable and slowly transforms to α-Al2O3 at high temperatures in an irreversible phase transition. During this transformation, the particles agglomerate, resulting in uneven distribution of the phases, which reduces the mechanical strength of the product and affects its final performance. The present invention utilizes a mineralizer calcination process to prepare calcined α-Al2O3. This not only reduces the content of impurities such as sodium in the alumina, improving its purity, but also avoids the technical problems of uneven phase distribution and reduced mechanical strength caused by γ-Al2O3.

[0008] Adding an appropriate amount of calcined α-Al2O3 to electronic ceramic materials imparts excellent mechanical and chemical properties. Compared to other common ceramic materials, the formation of an aluminum-oxygen tetrahedral structure and the resulting microcrystal strengthening give it superior mechanical properties. Calcining α-Al2O3 improves the heat resistance and corrosion resistance of electronic ceramic materials, making them more stable. Calcining α-Al2O3 also increases the hardness and tensile strength of electronic ceramic materials. The addition of aluminum enhances the strength and chemical stability of electronic ceramic materials. However, CaO, present in the electronic ceramic components, does not participate in the construction of the main network. Calcium ions have a large number of outer electrons and a large radius, making them less likely to precipitate. Adding a certain amount of CaO can balance the negative charge in the system and reduce defects in electronic ceramic materials.

[0009] However, SiO2-Al2O3-CaO electronic ceramic materials still have the problems of high thermal expansion coefficient and poor thermal stability. In order to improve the stability of electronic ceramic materials, the present invention adds a certain amount of ZrO2. ZrO2 has a large cationic charge and a small ionic radius, which can effectively improve the hardness and mechanical properties of electronic ceramic materials. At the same time, ZrO2 can easily lead to an increase in the viscosity of electronic ceramic materials, which is not conducive to melt processing and can easily lead to an increase in pores and microcracks. The addition of ZnO and La2O3 effectively solves the problems that may be caused by the addition of ZrO2. ZnO inhibits the formation of large-sized grains and refines the size of the precipitated grains, which not only helps to improve the toughness and hardness of the electronic ceramic material, but also improves its density, makes its structure more complete, and improves the stability of the electronic ceramic material. La2O3, as a rare earth element, has a smaller atomic radius than cerium and is not prone to lattice distortion. An appropriate amount of La2O3 can play a role in accumulation, preventing the network structure of the electronic ceramic material from relaxing, improving its stability, and reducing the thermal expansion coefficient. The amount of ZnO and La2O3 should be controlled within a certain range, otherwise, ZnO and La2O3 may cause network structure distortion, destroy the network structure, and lead to reduced network integrity in electronic ceramic materials, loose structure, and increased expansion coefficient.

[0010] Furthermore, the following components are included, by weight: 72-78 parts SiO2, 15-19 parts calcined α-Al2O3, 8-12 parts CaO, 0.5-3 parts ZrO2, 1-5 parts ZnO, 0.5-2.5 parts La2O3, 0.5-2 parts Li2O, and 0.1-0.5 parts K2O; where 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 electronic ceramic materials, but its large ionic radius can easily lead to a loose glass structure and reduced ion binding capacity. The higher the temperature, the greater the amplitude of proton motion in the glass-ceramic, the larger the distance between particles, and thus the higher the thermal expansion coefficient, resulting in system instability.

[0011] Furthermore, the composition comprises the following components, calculated by weight: 72.5-77.5 parts SiO2, 15.5-18 parts calcined α-Al2O3, 8.5-11 parts CaO, 1-3 parts ZrO2, 1-5 parts ZnO, 0.5-2.5 parts La2O3, 0.5-2 parts Li2O, and 0.1-0.5 parts K2O, with the mass of ZnO being a and the mass of La2O3 being b, and 1.5≤a / b≤2. The mixed alkali metal and alkaline earth metal effect demonstrates a nonlinear relationship between the ratio of different alkali metal ions and the structure and properties of the electronic ceramic material, and varies with the size and amount of the alkali and alkaline earth metal ions. When an appropriate amount of alkaline earth metal cations is introduced into the electronic ceramic material, a higher activation energy is generated and ion mobility is reduced, which increases the network rigidity of the electronic ceramic material and reduces plastic flow, thereby enhancing the mechanical properties and chemical stability of the electronic ceramic material.

[0012] On the other hand, the present invention also provides a method for preparing an electronic ceramic material based on calcined α-Al2O3, comprising the following steps:

[0013] Weighing raw materials, and mixing them evenly to obtain a mixture;

[0014] melting the mixed material to prepare a molten liquid;

[0015] The melt is poured into a mold for forming, and after annealing, an electronic ceramic material based on calcined α-Al2O3 is obtained;

[0016] Furthermore, the preparation process of calcined α-Al2O3 is:

[0017] After industrial γ-Al2O3 is ground, screened, and impurities removed, a mineralizer is added, mixed evenly, calcined at high temperature, and cooled to obtain calcined α-Al2O3.

[0018] Furthermore, the mineralizer is at least one of boric acid and ammonium salt, and its mass is 0.2-1wt% of industrial γ-Al2O3; the calcination temperature is 1300-1400°C, and the calcination time is 3-4h.

[0019] Furthermore, the raw materials are mixed by grinding.

[0020] Furthermore, the mixture is melted at a temperature of 1500-1700° C. for 4-5 hours.

[0021] Furthermore, the mold is a steel plate mold, a cast iron mold or a graphite mold; and the annealing process is carried out in a muffle furnace or a box-type resistance furnace.

[0022] Furthermore, the annealing temperature is 640-720°C for 1-3 hours. By adjusting the electronic ceramic material formula and the melting and heat treatment processes, the type of crystalline phase precipitation, crystallinity, and grain size in the electronic ceramic material structure can be controlled, resulting in ceramic materials with a large number of nano-scale grains, and thus high-strength, dimensionally stable, and excellent electronic ceramic products.

[0023] Beneficial effects:

[0024] Adding an appropriate amount of calcined α-Al2O3 to electronic ceramic materials imparts excellent mechanical and chemical properties. Compared to other common ceramic materials, the formation of an aluminum oxide tetrahedron structure and the microcrystal strengthening effect give it strong mechanical properties. ZrO2 has a high cationic charge and a small ionic radius, which can effectively improve the hardness and mechanical properties of electronic ceramic materials. ZnO inhibits the formation of large-sized grains, resulting in a smaller precipitated grain size, which not only helps to improve the toughness and hardness of electronic ceramic materials, but also increases their density, makes their structure more complete, and improves the stability of electronic ceramic materials. La2O3, as a rare earth element, has a smaller atomic radius than cerium and is less likely to cause lattice distortion. An appropriate amount of La2O3 can play a role in accumulation, preventing the network structure of electronic ceramic materials from relaxing, improving their stability, and reducing the thermal expansion coefficient, making electronic ceramic materials particularly suitable for the production of large electrical components. DETAILED DESCRIPTION

[0025] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0026] Example 1

[0027] An electronic ceramic material based on calcined α-Al2O3, comprising the following components in parts by weight:

[0028] 70 parts of SiO2, 15 parts of calcined α-Al2O3, 8 parts of CaO, 1 part of ZrO2, 1 part of ZnO, 0.5 parts of La2O3, 0.5 parts of Li2O, and 0.1 parts of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b=2.00.

[0029] The preparation method of the electronic ceramic material comprises the following steps:

[0030] Weigh each raw material, grind each raw material evenly to obtain a mixture;

[0031] The mixture is melted to prepare a melt; the melting temperature of the mixture is 1550°C and the melting time is 5 hours;

[0032] The melt was poured into a graphite mold and annealed in a muffle furnace to obtain an electronic ceramic material based on calcined α-Al2O3; the annealing temperature was 640°C and the time was 3 hours;

[0033] Wherein, the preparation process of calcined α-Al2O3 is:

[0034] Industrial γ-Al2O3 is ground, screened, and impurities removed, and then boric acid is added and mixed evenly. The mixture is calcined at high temperature and cooled to obtain calcined α-Al2O3. The mass of boric acid is 0.5wt% of the industrial γ-Al2O3. The calcination temperature is 1370°C and the calcination time is 3.4h.

[0035] Example 2

[0036] An electronic ceramic material based on calcined α-Al2O3, comprising the following components in parts by weight:

[0037] 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, and 1 part of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b=2.00.

[0038] The preparation method of the electronic ceramic material comprises the following steps:

[0039] Weigh each raw material, grind each raw material evenly to obtain a mixture;

[0040] The mixture is melted to prepare a melt; the melting temperature of the mixture is 1650°C and the melting time is 4 hours;

[0041] The melt was poured into a graphite mold and annealed in a muffle furnace to obtain an electronic ceramic material based on calcined α-Al2O3; the annealing temperature was 720°C and the time was 1.5 hours;

[0042] Wherein, the preparation process of calcined α-Al2O3 is:

[0043] Industrial γ-Al2O3 is ground, screened, and impurities removed, and then boric acid is added and mixed evenly. The mixture is calcined at high temperature and cooled to obtain calcined α-Al2O3. The mass of boric acid is 0.5wt% of the industrial γ-Al2O3. The calcination temperature is 1370°C and the calcination time is 3.4h.

[0044] Example 3

[0045] An electronic ceramic material based on calcined α-Al2O3, comprising the following components in parts by weight:

[0046] 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, and 0.3 parts of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b=1.50.

[0047] The preparation method of the electronic ceramic material comprises the following steps:

[0048] Weigh each raw material, grind each raw material evenly to obtain a mixture;

[0049] The mixture is melted to prepare a melt; the melting temperature of the mixture is 1580°C and the melting time is 4.7 hours;

[0050] The melt was poured into a graphite mold and annealed in a muffle furnace to obtain an electronic ceramic material based on calcined α-Al2O3; the annealing temperature was 650°C and the time was 2.6 hours;

[0051] Wherein, the preparation process of calcined α-Al2O3 is:

[0052] Industrial γ-Al2O3 is ground, screened, and impurities removed, and then boric acid is added and mixed evenly. The mixture is calcined at high temperature and cooled to obtain calcined α-Al2O3. The mass of boric acid is 0.5wt% of the industrial γ-Al2O3. The calcination temperature is 1370°C and the calcination time is 3.4h.

[0053] Example 4

[0054] An electronic ceramic material based on calcined α-Al2O3, comprising the following components in parts by weight:

[0055] SiO2 73 parts, calcined α-Al2O3 16 parts, CaO 9 parts, ZrO2 1.5 parts, ZnO 3.2 parts, La2O3 2 parts, Li2O 1.6 parts, K2O 0.8 parts; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b=1.60.

[0056] The preparation method of the electronic ceramic material comprises the following steps:

[0057] Weigh each raw material, grind each raw material evenly to obtain a mixture;

[0058] The mixture is melted to prepare a melt; the melting temperature of the mixture is 1620°C and the melting time is 4.2 hours;

[0059] The melt was poured into a graphite mold and annealed in a muffle furnace to obtain an electronic ceramic material based on calcined α-Al2O3; the annealing temperature was 680°C and the time was 2.3 hours;

[0060] Wherein, the preparation process of calcined α-Al2O3 is:

[0061] Industrial γ-Al2O3 is ground, screened, and impurities removed, and then boric acid is added and mixed evenly. The mixture is calcined at high temperature and cooled to obtain calcined α-Al2O3. The mass of boric acid is 0.5wt% of the industrial γ-Al2O3. The calcination temperature is 1370°C and the calcination time is 3.4h.

[0062] Example 5

[0063] An electronic ceramic material based on calcined α-Al2O3, comprising the following components in parts by weight:

[0064] 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, and 0.3 parts of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b=1.91.

[0065] The preparation method of the electronic ceramic material comprises the following steps:

[0066] Weigh each raw material, grind each raw material evenly to obtain a mixture;

[0067] The mixture is melted to prepare a melt; the melting temperature of the mixture is 1590°C and the melting time is 4.7 hours;

[0068] The melt was poured into a graphite mold and annealed in a muffle furnace to obtain an electronic ceramic material based on calcined α-Al2O3; the annealing temperature was 660°C and the time was 2.2 hours;

[0069] Wherein, the preparation process of calcined α-Al2O3 is:

[0070] Industrial γ-Al2O3 is ground, screened, and impurities removed, and then boric acid is added and mixed evenly. The mixture is calcined at high temperature and cooled to obtain calcined α-Al2O3. The mass of boric acid is 0.5wt% of the industrial γ-Al2O3. The calcination temperature is 1370°C and the calcination time is 3.4h.

[0071] Example 6

[0072] An electronic ceramic material based on calcined α-Al2O3, comprising the following components in parts by weight:

[0073] 76 parts of SiO2, 16.5 parts of calcined α-Al2O3, 10 parts of CaO, 0.5 parts of ZrO2, 2.7 parts of ZnO, 1.5 parts of La2O3, 1.6 parts of Li2O, and 0.6 parts of K2O; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b=1.80.

[0074] The preparation method of the electronic ceramic material comprises the following steps:

[0075] Weigh each raw material, grind each raw material evenly to obtain a mixture;

[0076] The mixture is melted to prepare a melt; the melting temperature of the mixture is 1600°C and the melting time is 4.1 hours;

[0077] The melt was poured into a graphite mold and annealed in a muffle furnace to obtain an electronic ceramic material based on calcined α-Al2O3; the annealing temperature was 690°C and the time was 2.2 hours;

[0078] Wherein, the preparation process of calcined α-Al2O3 is:

[0079] Industrial γ-Al2O3 is ground, screened, and impurities removed, and then boric acid is added and mixed evenly. The mixture is calcined at high temperature and cooled to obtain calcined α-Al2O3. The mass of boric acid is 0.5wt% of the industrial γ-Al2O3. The calcination temperature is 1370°C and the calcination time is 3.4h.

[0080] Example 7

[0081] An electronic ceramic material based on calcined α-Al2O3, comprising the following components in parts by weight:

[0082] SiO2 76 parts, calcined α-Al2O3 17.4 parts, CaO 9.6 parts, ZrO2 2.3 parts, ZnO 3 parts, La2O3 1.6 parts, Li2O 1.7 parts, K2O 0.3 parts; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b=1.88.

[0083] The preparation method of the electronic ceramic material comprises the following steps:

[0084] Weigh each raw material, grind each raw material evenly to obtain a mixture;

[0085] The mixture is melted to prepare a melt; the melting temperature of the mixture is 1590°C and the melting time is 4.6 hours;

[0086] The melt was poured into a graphite mold and annealed in a muffle furnace to obtain an electronic ceramic material based on calcined α-Al2O3; the annealing temperature was 690°C and the time was 2.7 hours;

[0087] Wherein, the preparation process of calcined α-Al2O3 is:

[0088] Industrial γ-Al2O3 is ground, screened, and impurities removed, and then boric acid is added and mixed evenly. The mixture is calcined at high temperature and cooled to obtain calcined α-Al2O3. The mass of boric acid is 0.5wt% of the industrial γ-Al2O3. The calcination temperature is 1370°C and the calcination time is 3.4h.

[0089] Example 8

[0090] An electronic ceramic material based on calcined α-Al2O3, comprising the following components in parts by weight:

[0091] SiO2 76 parts, calcined α-Al2O3 16.5 parts, CaO 10 parts, ZrO2 5 parts, ZnO 2.7 parts, La2O3 1.5 parts, Li2O 1.6 parts, K2O 0.6 parts; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b=1.80.

[0092] The preparation method of the electronic ceramic material comprises the following steps:

[0093] Weigh each raw material, grind each raw material evenly to obtain a mixture;

[0094] The mixture is melted to prepare a melt; the melting temperature of the mixture is 1600°C and the melting time is 4.1 hours;

[0095] The melt was poured into a graphite mold and annealed in a muffle furnace to obtain an electronic ceramic material based on calcined α-Al2O3; the annealing temperature was 690°C and the time was 2.2 hours;

[0096] Wherein, the preparation process of calcined α-Al2O3 is:

[0097] Industrial γ-Al2O3 is ground, screened, and impurities removed, and then boric acid is added and mixed evenly. The mixture is calcined at high temperature and cooled to obtain calcined α-Al2O3. The mass of boric acid is 0.5wt% of the industrial γ-Al2O3. The calcination temperature is 1370°C and the calcination time is 3.4h.

[0098] Example 9

[0099] An electronic ceramic material based on calcined α-Al2O3, comprising the following components in parts by weight:

[0100] SiO2 71 parts, calcined α-Al2O3 17.2 parts, CaO 9.8 parts, ZrO2 2.3 parts, ZnO 1.4 parts, La2O3 0.9 parts, Li2O 1.3 parts, K2O 0.4 parts; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b=1.56.

[0101] The preparation method of the electronic ceramic material comprises the following steps:

[0102] Weigh each raw material, grind each raw material evenly to obtain a mixture;

[0103] The mixture is melted to prepare a melt; the melting temperature of the mixture is 1580°C and the melting time is 4.7 hours;

[0104] The melt was poured into a graphite mold and annealed in a muffle furnace to obtain an electronic ceramic material based on calcined α-Al2O3; the annealing temperature was 690°C and the time was 1.9 hours;

[0105] Wherein, the preparation process of calcined α-Al2O3 is:

[0106] Industrial γ-Al2O3 is ground, screened, and impurities removed, and then boric acid is added and mixed evenly. The mixture is calcined at high temperature and cooled to obtain calcined α-Al2O3. The mass of boric acid is 0.5wt% of the industrial γ-Al2O3. The calcination temperature is 1370°C and the calcination time is 3.4h.

[0107] Example 10

[0108] An electronic ceramic material based on calcined α-Al2O3, comprising the following components in parts by weight:

[0109] SiO2 76 parts, calcined α-Al2O3 16.5 parts, CaO 15 parts, ZrO2 2 parts, ZnO 2.7 parts, La2O3 1.5 parts, Li2O 1.6 parts, K2O 0.6 parts; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b=1.80.

[0110] The preparation method of the electronic ceramic material comprises the following steps:

[0111] Weigh each raw material, grind each raw material evenly to obtain a mixture;

[0112] The mixture is melted to prepare a melt; the melting temperature of the mixture is 1600°C and the melting time is 4.1 hours;

[0113] The melt was poured into a graphite mold and annealed in a muffle furnace to obtain an electronic ceramic material based on calcined α-Al2O3; the annealing temperature was 690°C and the time was 2.2 hours;

[0114] Wherein, the preparation process of calcined α-Al2O3 is:

[0115] Industrial γ-Al2O3 is ground, screened, and impurities removed, and then boric acid is added and mixed evenly. The mixture is calcined at high temperature and cooled to obtain calcined α-Al2O3. The mass of boric acid is 0.5wt% of the industrial γ-Al2O3. The calcination temperature is 1370°C and the calcination time is 3.4h.

[0116] Example 11

[0117] An electronic ceramic material based on calcined α-Al2O3, comprising the following components in parts by weight:

[0118] SiO2 75.5 parts, calcined α-Al2O3 15.8 parts, CaO 9.5 parts, ZrO2 2.6 parts, ZnO 3.9 parts, La2O3 2.4 parts, Li2O 0.8 parts, K2O 0.2 parts; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b=1.63.

[0119] The preparation method of the electronic ceramic material comprises the following steps:

[0120] Weigh each raw material, grind each raw material evenly to obtain a mixture;

[0121] The mixture is melted to prepare a melt; the mixture melting temperature is 1560°C and the melting time is 4.9 hours;

[0122] The melt was poured into a graphite mold and annealed in a muffle furnace to obtain an electronic ceramic material based on calcined α-Al2O3; the annealing temperature was 710°C and the time was 1.5 hours;

[0123] Wherein, the preparation process of calcined α-Al2O3 is:

[0124] Industrial γ-Al2O3 is ground, screened, and impurities removed, and then boric acid is added and mixed evenly. The mixture is calcined at high temperature and cooled to obtain calcined α-Al2O3. The mass of boric acid is 0.5wt% of the industrial γ-Al2O3. The calcination temperature is 1370°C and the calcination time is 3.4h.

[0125] Example 12

[0126] An electronic ceramic material based on calcined α-Al2O3, comprising the following components in parts by weight:

[0127] SiO2 76 parts, calcined α-Al2O3 16.5 parts, CaO 10 parts, ZrO2 2 parts, ZnO 2.7 parts, La2O3 1.5 parts, Li2O 1.6 parts, K2O 0.6 parts; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b=1.80.

[0128] The preparation method of the electronic ceramic material comprises the following steps:

[0129] Weigh each raw material, grind each raw material evenly to obtain a mixture;

[0130] The mixture is melted to prepare a melt; the melting temperature of the mixture is 1600°C and the melting time is 4.1 hours;

[0131] The melt was poured into a graphite mold and annealed in a muffle furnace to obtain an electronic ceramic material based on calcined α-Al2O3; the annealing temperature was 690°C and the time was 2.2 hours;

[0132] Wherein, the preparation process of calcined α-Al2O3 is:

[0133] Industrial γ-Al2O3 is ground, screened, and impurities removed, and then boric acid is added and mixed evenly. The mixture is calcined at high temperature and cooled to obtain calcined α-Al2O3. The mass of boric acid is 0.5wt% of the industrial γ-Al2O3. The calcination temperature is 1370°C and the calcination time is 3.4h.

[0134] Comparative Example 1

[0135] Its components and raw materials are basically the same as those in Example 12, with the difference being: 2 parts of ZnO and 2 parts of La2O3; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b=1.

[0136] Comparative Example 2

[0137] Its components and raw materials are basically the same as those in Example 12, except that: ZnO is 2.3 parts and La2O3 is 1 part; that is, the mass of ZnO is a, the mass of La2O3 is b, and a / b=2.30.

[0138] Performance testing:

[0139] The electronic ceramic materials based on calcined α-Al2O3 prepared in the examples and comparative examples were prepared into standard specimens, and their flexural strength (GB / T6569-2006), Vickers hardness (ASTM E-384), and thermal expansion coefficient (50-350°C, ASTM E-228) were tested by the three-point bending method. The results are shown in Tables 1-2.

[0140] Table 1 Properties of electronic ceramic materials based on calcined α-Al2O3 prepared in Examples 1-7

[0141]

[0142] Table 2 Properties of electronic ceramic materials based on calcined α-Al2O3 prepared in Examples 8-12 and Comparative Examples 1-2

[0143]

[0144] As can be seen from Tables 1 and 2, ZrO2 has a high cationic charge and a small ionic radius, which can effectively improve the hardness and mechanical properties of electronic ceramic materials. At the same time, ZrO2 can also easily increase the viscosity of electronic ceramic materials, making them unfavorable for melt processing and easily leading to increased porosity and microcracks. The addition of ZnO and La2O3 effectively solves the problems that may be caused by the addition of ZrO2. ZnO inhibits the formation of large-sized grains and refines the size of the precipitated grains, which not only helps to improve the strength and hardness of electronic ceramic materials, but also increases their density, makes their structure more complete, and improves the stability of electronic ceramic materials. La2O3, as a rare earth element, has a smaller atomic radius than cerium and is less likely to cause lattice distortion. An appropriate amount of La2O3 can play a role in accumulation, preventing the network structure of electronic ceramic materials from relaxing, improving their stability, and reducing the thermal expansion coefficient.

[0145] Compared with Example 12, the amounts of ZnO and La2O3 in Comparative Examples 1 and 2 are not controlled within a certain range, which will lead to network structure distortion and destruction of the network structure, resulting in reduced network integrity in the electronic ceramic material, loose structure, and increased expansion coefficient.

[0146] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0147] The above-described embodiments merely represent several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the spirit of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be based on the appended claims, and the description may be used to interpret the content of the claims.

Claims

1. An electronic ceramic material based on calcined α-Al2O3, characterized in that: In parts by weight, it is composed of the following components: SiO2 72.5-77.5 parts, calcined α-Al2O3 15.5-18 parts, CaO 8.5-11 parts, ZrO2 1-3 parts, ZnO 1-5 parts, La2O3 0.5-2.5 parts, Li2O 0.5-2 parts, K2O 0.1-0.5 parts, and the mass of ZnO is a, the mass of La2O3 is b, 1.5≤a / b≤2; The method for preparing an electronic ceramic material based on calcined α-Al2O3 comprises the following steps: Weigh the raw materials according to the components, mix the raw materials evenly, and obtain a mixture; melting the mixed material to prepare a molten liquid; The melt is poured into a mold for forming, and after annealing, an electronic ceramic material based on calcined α-Al2O3 is obtained.

2. The method for preparing an electronic ceramic material based on calcined α-Al2O3 according to claim 1, characterized in that: The steps include: Weigh the raw materials according to the components of claim 1, and mix the raw materials uniformly to obtain a mixture; melting the mixed material to prepare a molten liquid; The melt is poured into a mold for forming, and after annealing, an electronic ceramic material based on calcined α-Al2O3 is obtained.

3. The method for preparing an electronic ceramic material based on calcined α-Al2O3 according to claim 2, characterized in that: The preparation process of calcined α-Al2O3 is: After industrial γ-Al2O3 is ground, screened, and impurities removed, a mineralizer is added, mixed evenly, calcined at high temperature, and cooled to obtain calcined α-Al2O3.

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

5. The method for preparing an electronic ceramic material based on calcined α-Al2O3 according to claim 2, characterized in that: The raw materials are mixed by grinding.

6. The method for preparing an electronic ceramic material based on calcined α-Al2O3 according to claim 2, characterized in that: The melting temperature of the mixture is 1500-1700℃ and the melting time is 4-5h.

7. The method for preparing an electronic ceramic material based on calcined α-Al2O3 according to claim 2, characterized in that: The mold is a steel plate mold, a cast iron mold or a graphite mold; and the annealing process is carried out in a muffle furnace or a box-type resistance furnace.

8. The method for preparing an electronic ceramic material based on calcined α-Al2O3 according to claim 2, characterized in that: The annealing temperature is 640-720°C and the time is 1-3 hours.

Images