Novel talc porcelain material for hot die casting as well as preparation method and application of talc porcelain material

Abstract

The invention discloses a novel talc porcelain material for hot die casting and a preparation method and application thereof.The raw materials are composed of an inorganic matter formula and an organic binder, and the inorganic matter formula comprises 85-88 parts of calcined talcum powder, 5-10 parts of calcined kaolin, 0.1-5 parts of quasi-nano magnesium aluminate spinel, 5-20 parts of skeleton raw materials and 7-15 parts of heavy barium carbonate; the organic binder comprises 12-15% of paraffin, 0.1-1% of TPE and 0.3-1% of oleic acid according to the total mass of the inorganic matter formula, and the particle size of the quasi-nano magnesium aluminate spinel is 0.1-0.5 micron. The raw material cost is reduced by 25%, the slurry fluidity reaches 150 mm, the deformation degree of a hot die casting d30mm * 0.5 mm round pipe is smaller than 0.07 mm, the ceramic strength is larger than or equal to 170 MPa, the product percent of pass is increased to 95% from 85%, and the method can be widely applied to manufacturing of precise electronic insulation components.

Description

A novel talc ceramic material for hot pressing and casting, its preparation method and application Technical Field

[0001] This invention relates to the field of ceramic material preparation technology, specifically to a novel talc ceramic material for hot pressing and its preparation method, which is particularly suitable for the mass production of high-precision electronic ceramic components. Background Technology

[0002] Talc ceramics are widely used in the electronics industry due to their excellent insulation and processing properties. The traditional hot-pressing process for preparing talc ceramic wax cakes involves "mixing - ball milling - pressing - sintering - ball milling again - mixing with wax," which is lengthy and results in a raw material loss rate as high as 15-20%, leading to high production costs.

[0003] Meanwhile, the existing technology formula has three major defects: First, the amount of paraffin added needs to reach 15-20% to ensure fluidity, resulting in a heavy wax removal burden and low green strength; second, the grains are prone to abnormal growth during sintering, and the ceramic strength is generally lower than 140MPa; third, there is a lack of effective skeleton support, and the deformation of thin-walled components (such as round tubes with a thickness of <1mm) often exceeds 0.1mm, with a pass rate of only about 85%.

[0004] In the prior art, CN103880458A discloses a method for preparing alumina wax cake, but does not involve the optimization of the talc porcelain formula and the simplification of the process; CN104152838A mentions the application of talc porcelain wax cake, but does not solve the problem of insufficient molding accuracy and strength.

[0005] Therefore, developing a low-cost, high-performance talc ceramic material for hot pressing is of great practical significance. Summary of the Invention

[0006] To address the technical problems existing in the prior art, the present invention aims to provide a novel talc ceramic material for hot pressing and its preparation method and application, effectively solving the following problems: including the problems of excessive raw material costs and energy consumption caused by the lengthy traditional process; insufficient slurry fluidity and numerous molding defects under low paraffin dosage; large product deformation, low strength, and insufficient pass rate; and poor density of wax cake and green body caused by uneven particle size distribution in ball milling.

[0007] The objective of this invention is achieved through the following technical solution: a novel talc ceramic material for hot pressing, comprising an inorganic formula and an organic binder. The inorganic formula, by weight, includes 85-88 parts calcined talc powder, 5-10 parts calcined kaolin, 0.1-5 parts quasi-nano magnesium aluminum spinel, 5-20 parts framework material, and 7-15 parts heavy barium carbonate. The framework material is at least one of corundum sand, zircon sand, quartz sand, flaky alumina, fused mullite, calcium-stabilized zirconium oxide sand, and molybdenum disilicide. The organic binder, by weight of the total inorganic formula, includes 12-15% paraffin wax, 0.1-1% TPE, and 0.3-1% oleic acid. The quasi-nano magnesium aluminum spinel has a particle size of 0.1-0.5 micrometers.

[0008] Specifically, the calcined talc powder serves as the main crystalline phase. The content is ≥60% and the MgO content is ≥30%, and the crystal water is removed by pre-calcination at 1200-1300℃.

[0009] Furthermore, the softening temperature of the skeleton material is >1600℃.

[0010] Specifically, the corundum sand Content ≥99%; the zircon sand Content ≥98%; the quartz sand Content ≥99.5%; the aspect ratio of the flake alumina is 10-20:1; the heavy barium carbonate... Content ≥99%.

[0011] To address the aforementioned technical problems, this invention also provides another technical solution: a method for preparing a novel talc ceramic material for hot pressing, comprising the following steps:

[0012] S1. Prepare the ingredients and weigh them for later use;

[0013] S2.AB Two-stage ball mill:

[0014] A-stage ball milling: Add the calcined talc powder, calcined kaolin, skeleton raw materials and oleic acid to a ball mill and ball mill to control the particle size D50=3-10μm;

[0015] B-stage ball milling: Add the quasi-nano magnesium aluminum spinel and heavy barium carbonate to the slurry from the A-stage ball milling, continue ball milling, control the particle size standard D50=2-7μm, and the particle size ratio D90 / D50<3, D50 / D10<4; discharge and dry;

[0016] S3. Preparation of wax cake,

[0017] S4. Hot pressing: The wax cake is heated and melted into a slurry, which is then injected into a hot pressing machine to obtain a green blank;

[0018] S5. Powder embedding and wax removal;

[0019] S6. Sintering: The dewaxed blank is placed in a sintering furnace, heated to 1280-1320℃, held at that temperature for a period of time, and then cooled to room temperature with the furnace to obtain the finished product.

[0020] Traditional processes use raw ore as raw material, which has high water content and shrinkage, requiring mixing, briquetting, and sintering processes for solid-phase homogenization. In contrast, this invention uses calcined components as raw materials, homogenized in a ball mill, and densified using sintering aids. This results in a simplified process: "batching - two-stage ball milling (AB) - wax mixing," eliminating the briquetting and sintering steps of traditional processes and directly producing wax cakes. Subsequent hot-pressing, wax removal, and sintering yield the finished product. This invention reduces raw material costs by 25%, achieves slurry fluidity of 150mm, achieves a deformation of <0.07mm for hot-pressed 30mm×0.5mm round tubes, a ceramic strength ≥170MPa, and increases product qualification rate from 85% to 95%. It can be widely used in the manufacture of precision electronic insulating components.

[0021] Furthermore, in step S2, during ball milling in section A, alumina balls are used as the grinding medium, the material-to-ball ratio is 1:3, the rotation speed is 200-300 r / min, and ball milling is carried out for 3-8 hours; during ball milling in section B, the material-to-ball ratio and rotation speed are maintained, and ball milling is continued for 1-2 hours. The discharged material is dried until the moisture content is <0.2%, and after pulverization, it is passed through a 120-mesh sieve to remove impurities; and the alumina balls are graded with a particle size distribution of 30% Φ30mm, 60% Φ20mm, and 10% Φ50mm.

[0022] Specifically, step S3 includes the following steps:

[0023] ① Wax melting: Heat paraffin wax and TPE to 100-130℃ until completely melted, stir evenly, and make a binder solution;

[0024] ② Add wax: Add the dried powder to the binder solution and stir at 100-130℃ for 30-120 minutes;

[0025] ③ Cooling and shaping: Pour the mixed batter into a mold, let it cool naturally to room temperature, and then demold to obtain a dense wax cake.

[0026] Specifically, in step S5, the green blank is embedded in industrial alumina powder, placed in a dewaxing furnace, heated to 600°C at a rate of 0.2-1°C / min, held for 2-4 hours, and then heated to 900-1000°C at a rate of 0.5-2°C / min, held for 1-3 hours; wherein the particle size of the industrial alumina powder is 50-150 mesh.

[0027] Specifically, step S6 involves heating at a rate of 1-8 °C / min.

[0028] The method for preparing the novel talc ceramic material for hot pressing can be used to prepare insulating sleeves for electronic components, ceramic bases for high-frequency connectors, or ceramic components for precision sensors.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] 1. Significantly reduced costs: The simplified process eliminates the traditional steps of ball milling, briquetting, calcining, and crushing of raw materials, reducing the raw material loss rate from 18% to 3%, lowering costs by 25%, and shortening the process cycle by 40%.

[0031] 2. Excellent molding performance: When the paraffin content is 12-13%, the slurry fluidity (tested with a special fixture) reaches 150mm, which is 25% higher than the traditional process, and the green body fullness reaches 99%;

[0032] 3. Significantly improved precision: The supporting effect of the skeleton material makes the deformation of the d30mm×0.5mm round tube <0.07mm, which is more than 50% lower than that of traditional products (0.12-0.15mm);

[0033] 4. Enhanced mechanical properties: The addition of quasi-nano magnesium aluminum spinel increases the ceramic strength to ≥170MPa, reaching up to 185MPa, reduces the dewaxing defect rate from 12% to 3%, and increases the pass rate from 85% to 95%.

[0034] 5. Good process stability: Optimized particle size distribution ensures that the sintering shrinkage fluctuation range is ≤2% and the performance deviation between batches is <3%. Detailed Implementation

[0035] To facilitate understanding of the present invention, the technical solutions and advantages of the invention are further described in detail below with reference to embodiments. Any mechanisms or methods not elaborated in this invention can be referred to in the prior art. The specific structures and features of the present invention are described below by way of example and should not be construed as limiting the present invention in any way. Furthermore, any of the technical features mentioned below (including implicit or explicit) can be arbitrarily combined or deleted from these technical features to form more other embodiments that may not be directly or indirectly mentioned in this invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0036] The novel talc ceramic material for hot pressing of the present invention is composed of an inorganic formula and an organic binder.

[0037] Specifically, the inorganic formulation comprises, by weight, 85-88 parts of calcined talc powder, 5-10 parts of calcined kaolin, 0.1-5 parts of quasi-nano magnesium aluminum spinel, 5-20 parts of framework raw material, and 7-15 parts of heavy barium carbonate. The framework raw material is at least one of corundum sand, zircon sand, quartz sand, flaky alumina, fused mullite, calcium-stabilized zirconium oxide sand, and molybdenum disilicide.

[0038] The organic binder, by weight of the total inorganic formulation, includes 12-15% paraffin wax, 0.1-1% TPE, and 0.3-1% oleic acid.

[0039] The quasi-nano magnesium aluminum spinel has a particle size of 0.1-0.5 micrometers. TPE is a thermoplastic elastomer, and the material added in this invention is a commercially available conventional material. Calcium-stabilized zirconia sand is an electrofused oxide material prepared by stabilization treatment with calcium oxide as the core component. It has high refractoriness, excellent thermal shock stability, and corrosion resistance, and is mainly used in refractory materials, structural ceramics, and high-temperature casting.

[0040] The method for preparing the novel talc ceramic material for hot pressing of the present invention includes the following steps:

[0041] S1. Ingredients: Weigh each component according to the above proportions and set aside;

[0042] S2.AB Two-stage ball mill:

[0043] Section A ball milling: Add calcined talc, calcined kaolin, skeleton raw materials and oleic acid to the ball mill, use alumina balls as the grinding medium, material-to-ball ratio 1:3, speed 200-300 r / min, ball mill for 3-8 hours, and control the particle size D50=3-10μm.

[0044] B-stage ball milling: Add quasi-nano magnesium aluminum spinel and heavy barium carbonate to the slurry from the A-stage ball milling, maintaining the material-to-ball ratio and rotation speed, and continue ball milling for 1-2 hours. Use a laser particle size analyzer to test the particle size: control the standard particle size D50 = 2-7 ​​μm, and the particle size ratio D90 / D50 < 3, D50 / D10 < 4; dry the discharged material until the moisture content is < 0.2%, then pulverize and pass it through a 120-mesh sieve to remove impurities.

[0045] The alumina spheres are configured with a particle size distribution of 30% Φ30mm, 60% Φ20mm and 10% Φ50mm.

[0046] S3. Preparation of wax cake, specifically the following steps:

[0047] ① Wax melting: Heat paraffin wax and TPE to 100-130℃ until completely melted, stir evenly, and make a binder solution;

[0048] ② Add wax: Add the dried powder to the binder solution and stir at 100-130℃ for 30-120 minutes;

[0049] ③ Cooling and shaping: Pour the mixed batter into a mold, let it cool naturally to room temperature, and then demold to obtain a dense wax cake;

[0050] S4. Hot pressing molding: Heat the wax cake to 60-80℃ to melt it into a slurry, inject it into a hot pressing machine, and press it into shape under a pressure of 0.5-0.8MPa, holding the pressure for 10-30s to obtain a green blank;

[0051] S5. Powder embedding and wax removal: The green blank is embedded in industrial alumina powder, placed in a wax removal furnace, heated to 600℃ at a rate of 0.2-1℃ / min, held for 2-4 hours, and then heated to 900-1000℃ at a rate of 0.5-2℃ / min, held for 1-3 hours; wherein, the particle size of the industrial alumina powder is 50-150 mesh;

[0052] S6. Sintering: Place the dewaxed blank into a sintering furnace, heat it to 1280-1320℃ at a rate of 1-8℃ / min, hold it at that temperature for 1-2 hours, and then cool it to room temperature in the furnace to obtain the finished product.

[0053] The novel talc ceramic material for hot die casting of the present invention is used to prepare insulating sleeves for electronic components, ceramic bases for high-frequency connectors, or ceramic components for precision sensors.

[0054] The specific parameters of the preparation method of the present invention and the performance of the finished product are described in detail in Examples 1-5 below.

[0055] Example 1

[0056] The novel talc ceramic material for hot pressing in Example 1 has the following raw material ratio:

[0057] a. Inorganic formulation (by weight): 88 parts calcined talc powder (pre-calcined at 1250℃, D50=15μm), 5 parts calcined kaolin (pre-calcined at 1100℃). Content 38%), 0.1 parts of quasi-nano magnesium aluminum spinel, and 5 parts of framework raw material (quartz sand). ≥99.5%, D50=20μm) and 7 parts of heavy barium carbonate ( ≥99%).

[0058] b. Organic binders: based on the total mass of inorganic matter (2000g), paraffin 12% (240g), TPE 0.1% (2g) and oleic acid 0.3% (6g).

[0059] The preparation process of the novel steatite ceramic material for hot pressing in Example 1 includes the following steps:

[0060] S1. Ingredients: Accurately weigh the above inorganic raw materials, with an error controlled within ±0.1g; weigh the organic binder components separately and set aside.

[0061] S2.AB Two-stage ball mill:

[0062] Section A: Calcined talc powder, calcined kaolin, quartz sand, and oleic acid were added to a 5L ball mill, along with alumina balls (30% Φ30mm, 60% Φ20mm, and 10% Φ50mm), at a material-to-ball ratio of 1:3. The milling speed was 200 r / min, and the milling time was 8 hours. Samples were taken and tested using a laser particle size analyzer (Malvin Mastersizer 3000). The particle size D50 was 10μm, which meets the requirements.

[0063] Section B: Add quasi-nano magnesium aluminum spinel and heavy barium carbonate, maintain the material-to-ball ratio and rotation speed, and continue ball milling for 2 hours; test the particle size again: D50=7μm, D90 / D50=2.8, D50 / D10=3.5, satisfying D90 / D50<3, D50 / D10<4; pour the slurry into a tray and dry it in a 120℃ oven for 12 hours. After drying, the moisture content of the powder is tested to be 0.15%. After pulverizing, pass it through a 120-mesh sieve to remove impurities.

[0064] S3. Wax cake preparation:

[0065] ① Heat paraffin wax and TPE to 100-130℃ until completely melted, stir evenly, and prepare an adhesive solution;

[0066] ② Add the dried powder to the binder solution and stir at 100-130℃ for 120 minutes; cool and form into cakes;

[0067] ③ Pour into a mold, cool at room temperature for 30 minutes, and then unmold to obtain a wax cake.

[0068] S4. Hot die casting: The wax cake is heated to 60℃ to melt and injected into the hot die casting machine. The pressure is 0.5MPa and held for 30s. A d30mm×0.5mm round tube blank is cast, with a blank size deviation of ±0.02mm.

[0069] S5. Powder embedding and wax removal: The green body is embedded in 50-mesh pre-fired alumina powder, placed in a wax removal furnace, heated to 600℃ at 0.2℃ / min and held for 4 hours; then heated to 900℃ at 0.5℃ / min and held for 3 hours; after wax removal, the green body has no cracks and the weight loss is 11.8% (consistent with the theoretical binder content).

[0070] S6. Sintering: Place the dewaxed blank into a sintering furnace, heat it to 1280℃ at a rate of 1℃ / min, hold it for 2 hours, and then cool it with the furnace; the finished product has no defects in appearance and a dimensional shrinkage rate of 11%.

[0071] Performance testing was conducted on Example 1. Specifically, the slurry from step S4 was subjected to a flowability test, and the finished product obtained in step S6 was subjected to deformation and strength tests. The following results were obtained:

[0072] Slurry flowability: Using GB / T 14823.1-2016 standard fixtures, the test temperature was 60℃ and the flow diameter was 160mm;

[0073] Deformation: The maximum radial deviation of a d30mm×0.5mm round tube was measured using a coordinate measuring machine (model Leitz PMM-C), and was 0.06mm < 0.07mm.

[0074] Strength: The three-point bending strength was tested according to GB / T 8489-2006. The sample size was 4mm×3mm×36mm, the span was 30mm, the loading rate was 0.5mm / min, and the average strength was 178MPa.

[0075] Example 2

[0076] The novel talc ceramic material for hot pressing in Example 2 has the following material ratio:

[0077] a. Inorganic formulation (by weight): 86 parts calcined talc (pre-calcined at 1250℃), 8 parts calcined kaolin (pre-calcined at 1100℃), 3 parts quasi-nano magnesium aluminum spinel (particle size 0.3μm). ≥99%), 12 parts of skeleton raw material (sheet alumina, aspect ratio 15:1), ≥99%) and 10 parts of heavy barium carbonate.

[0078] b. Organic binders: based on the total mass of inorganic matter (2000g), paraffin 13.5% (270g), TPE 0.5% (10g) and oleic acid 0.6% (12g).

[0079] The preparation process of the novel talc ceramic material for hot pressing in Example 2 is roughly the same as that in Example 1, except that:

[0080] Section A ball milling: 250 r / min, 5 h, D50 = 6 μm;

[0081] Section B ball milling: Continue ball milling for 1.5 hours, D50=4μm, D90 / D50=2.5, D50 / D10=3.2;

[0082] Wax cake preparation: The wax material is melted at 115℃ and stirred for 90 minutes;

[0083] Hot die casting: temperature 70℃, pressure 0.65MPa, holding pressure for 20s;

[0084] Wax removal: Heating rate 0.6℃ / min (before 600℃), 1℃ / min (600-1000℃), hold for 2h (600℃), hold for 2h (1000℃);

[0085] Sintering: Heat to 1300℃ at a rate of 5℃ / min and hold for 1.5h.

[0086] Performance testing was conducted on Example 2. Specifically, the slurry from step S4 was subjected to a flowability test, and the finished product obtained in step S6 was subjected to deformation and strength tests. The following results were obtained:

[0087] Slurry flowability: Tested at 70℃, flow diameter 162mm;

[0088] Deformation: d30mm×0.5mm, circular tube deformation 0.05mm<0.07mm;

[0089] Strength: Three-point bending strength ≥ 170 MPa (180 MPa);

[0090] Pass rate: Out of 100 pieces, 96 pieces passed, with a pass rate of 96%.

[0091] Example 3

[0092] The novel talc ceramic material for hot pressing in Example 3 has the following material ratio:

[0093] a. Inorganic formulation (by weight): 85 parts calcined talc, 10 parts calcined kaolin, 5 parts quasi-nano magnesium aluminum spinel (particle size 0.1μm), 20 parts skeletal raw materials (including 7 parts corundum sand and 13 parts zircon sand), and 15 parts heavy barium carbonate.

[0094] b. Organic binder: based on the total mass of inorganic matter (2000g), paraffin 15% (300g), TPE 1% (20g), oleic acid 1% (20g).

[0095] The preparation process of the novel talc ceramic material for hot pressing in Example 3 is roughly the same as that in Example 1, except that:

[0096] Section A ball milling: rotation speed 300 r / min, ball milling for 3 h, D50 = 3 μm;

[0097] Section B ball milling: Continue ball milling for 1 hour, D50=2μm, D90 / D50=2.2, D50 / D10=2.8;

[0098] Wax cake preparation: The wax material is melted at 130℃ and stirred for 30 minutes. The density of the wax cake is 1.90 g / cm³.

[0099] Hot die casting: temperature 80℃, pressure 0.8MPa, holding pressure for 10s;

[0100] Wax removal: Heating rate 1℃ / min (before 600℃), 2℃ / min (600-1000℃), hold for 2h (600℃), hold for 1h (1000℃);

[0101] Sintering: Heat to 1320℃ at 8℃ / min and hold for 1 hour.

[0102] Performance testing was conducted on Example 3. Specifically, the slurry from step S4 was subjected to a flowability test, and the finished product obtained in step S6 was subjected to deformation and strength tests. The following results were obtained:

[0103] Slurry flowability: Tested at 80℃, flow diameter 155mm;

[0104] Deformation: d30mm×0.5mm, circular tube deformation 0.04mm<0.07mm;

[0105] Strength: Three-point bending strength ≥ 170 MPa (185 MPa);

[0106] Pass rate: Out of 100 pieces, 97 pieces passed, with a pass rate of 97%.

[0107] Example 4

[0108] The novel talc ceramic material for hot pressing in Example 4 has the following material ratio:

[0109] a. Inorganic formulation (by weight): 85 parts calcined talc, 10 parts calcined kaolin, 4 parts quasi-nano magnesium aluminum spinel (particle size 0.1μm), 20 parts skeletal raw materials (including 6 parts fused mullite, 10 parts calcium-stabilized zirconium oxide sand and 4 parts molybdenum disilicide), and 15 parts heavy barium carbonate.

[0110] b. Organic binder: based on the total mass of inorganic matter (2000g), paraffin 15% (300g), TPE 1% (20g), oleic acid 1% (20g).

[0111] The preparation process of the novel talc ceramic material for hot pressing in Example 4 is roughly the same as that in Example 1, except that:

[0112] Section A ball milling: rotation speed 300 r / min, ball milling for 3 h, D50 = 3 μm;

[0113] Section B ball milling: Continue ball milling for 1 hour, D50=2μm, D90 / D50=2.2, D50 / D10=2.8;

[0114] Wax cake preparation: The wax material is melted at 130℃ and stirred for 30 minutes. The density of the wax cake is 1.90 g / cm³.

[0115] Hot die casting: temperature 80℃, pressure 0.8MPa, holding pressure for 10s;

[0116] Wax removal: Heating rate 1℃ / min (before 600℃), 2℃ / min (600-1000℃), hold for 2h (600℃), hold for 1h (1000℃);

[0117] Sintering: Heat to 1320℃ at 8℃ / min and hold for 1 hour.

[0118] Example 5

[0119] Using the materials and processes described in Example 2, an insulating sleeve (for electronic transformers) with a diameter of Φ5mm × 1mm × 50mm was prepared. The resulting insulating sleeve for electronic components was tested and found to be:

[0120] Dielectric strength: ≥20kV / mm (GB / T 1408.1-2022);

[0121] Volume resistivity: (GB / T 1410-2006);

[0122] Temperature resistance: After being kept at 200℃ for 1000 hours, the strength retention rate is 95%;

[0123] Batch production of 5,000 units with a pass rate of 96% meets the demand for bulk supply of electronic components.

[0124] Compared with the prior art, the design mechanism and innovation of this invention are mainly reflected in the following six aspects:

[0125] 1. Calcined talc powder is used as the main crystalline phase. With a content ≥60% and MgO content ≥30%, pre-calcination at 1200-1300℃ to remove water of crystallization can significantly reduce the subsequent sintering shrinkage rate, providing the material with basic insulation properties (volume resistivity ≥). ) and machinability.

[0126] 2. Quasi-nano magnesium aluminum spinel, with a particle size of 0.1-0.5 μm, inhibits abnormal grain growth while improving the strength of alumina ceramics through the pinning grain boundary effect. Specifically, when magnesium aluminum spinel is uniformly dispersed in the alumina matrix as submicron-sized particles, it forms "obstacles" along the grain boundary migration path (alumina grain growth depends on the movement of grain boundaries towards the center of curvature, while spinel particles "pin" the grain boundaries, requiring grain boundary migration to overcome additional energy barriers. We verified that the pinning effect is most significant when the particle size of magnesium aluminum spinel is 0.1-0.5 μm). The nano-sized particles can fill the gaps between coarse particles, increasing the powder bulk density to 1.8-2.0 g / cm³ and improving the compactness of the wax cake.

[0127] 3. The raw material for the skeleton is corundum sand ( Content ≥99%), zircon sand ( Content ≥98%), quartz sand ( At least one of the following: content ≥99.5% or flake alumina (diameter-to-thickness ratio 10-20:1), which utilizes its high-temperature stability (softening temperature >1600℃) to suppress sintering shrinkage deformation. The two-dimensional structure of flake alumina can improve the uniformity of stress distribution by 30%, further reducing the risk of cracking in thin-walled parts.

[0128] 4. Synergistic effect of organic binders: Paraffin wax provides molding fluidity, and oleic acid combines with the hydroxyl groups on the powder surface through hydroxyl groups, improving the wettability of the powder (the contact angle is reduced from 65° to below 30°). High fluidity can be achieved with low paraffin wax content, solving the technical contradiction of traditional formulas that "15-20% paraffin wax content is required to ensure fluidity". At the same time, low paraffin wax content can effectively reduce volume shrinkage during the wax removal stage (from 18% to 12%).

[0129] 5. AB Two-stage ball milling: First, grind the coarse-particle raw materials (calcined talc powder, skeletal raw materials) to a D50 of 3-10μm, then add fine-particle raw materials (quasi-nano magnesium aluminum spinel, heavy barium carbonate) and continue grinding until the D50 is 2-7μm, and the particle size ratio D90 / D50<3, D50 / D10<4, forming a "coarse-fine" gradient distribution, making the particle size distribution curve smoother, and increasing the apparent bulk density of the wax cake by 15-20%.

[0130] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, it will be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A novel talc ceramic material for hot pressing, characterized in that, It is composed of an inorganic formula and an organic binder. The inorganic formula, by weight, includes 85-88 parts of calcined talc, 5-10 parts of calcined kaolin, 0.1-5 parts of quasi-nano magnesium aluminum spinel, 5-20 parts of framework raw material, and 7-15 parts of heavy barium carbonate. The framework raw material is at least one of corundum sand, zircon sand, quartz sand, flaky alumina, fused mullite, calcium-stabilized zirconium oxide sand, and molybdenum disilicide. The organic binder, by weight of the total inorganic formula, includes 12-15% paraffin wax, 0.1-1% TPE, and 0.3-1% oleic acid. The quasi-nano magnesium aluminum spinel has a particle size of 0.1-0.5 micrometers.

2. The novel talc ceramic material for hot pressing as described in claim 1, characterized in that, The calcined talc powder serves as the main crystalline phase. The content is ≥60%, and the MgO content is ≥30%. It is pre-calcined at 1200-1300℃ to remove the water of crystallization.

3. The novel talc ceramic material for hot pressing as described in claim 1, characterized in that, The softening temperature of the skeleton material is >1600℃.

4. The novel talc ceramic material for hot pressing as described in claim 1, characterized in that, The corundum sand Content ≥99%; the zircon sand Content ≥98%; the quartz sand Content ≥99.5%; the aspect ratio of the flake alumina is 10-20:1; the heavy barium carbonate... Content ≥99%.

5. A method for preparing a novel talc ceramic material for hot pressing as described in any one of claims 1-4, characterized in that, The process includes the following steps: S1. Ingredient preparation and weighing; S2. Two-stage ball milling (A and B stages): Stage A: Add the calcined talc powder, calcined kaolin, skeletal raw materials, and oleic acid to a ball mill and mill to control the particle size D50 = 3-10 μm; Stage B: Add the quasi-nano magnesium aluminum spinel and heavy barium carbonate to the slurry from Stage A and continue milling to control the standard particle size D50 = 2-7 ​​μm, and the particle size ratio D90 / D50 < 3, D50 / D10 < 4; discharge and dry; S3. Wax cake preparation; S4. Hot pressing and casting: Heat and melt the wax cake into a slurry, inject it into a hot pressing and casting machine to obtain a green body; S5. Powder embedding and wax removal; S6. Sintering: Place the wax-removed green body into a sintering furnace, heat it to 1280-1320℃, hold it at that temperature for a period of time, and then cool it to room temperature with the furnace to obtain the finished product.

6. The preparation method of the novel talc ceramic material for hot pressing as described in claim 5, characterized in that, In step S2, during ball milling in section A, alumina balls are used as the grinding medium, with a material-to-ball ratio of 1:3, a rotation speed of 200-300 r / min, and ball milling for 3-8 hours; during ball milling in section B, the material-to-ball ratio and rotation speed are maintained, and ball milling continues for 1-2 hours. The discharged material is dried until the moisture content is <0.2%, and after pulverization, it is passed through a 120-mesh sieve to remove impurities; and the alumina balls are graded with a particle size distribution of 30% Φ30mm, 60% Φ20mm, and 10% Φ50mm.

7. The method for preparing the novel talc ceramic material for hot pressing as described in claim 5, characterized in that, Step S3 includes the following steps: ① Wax melting: Heat paraffin wax and TPE to 100-130℃ to completely melt, stir evenly, and make a binder solution; ② Mixing wax: Add dried powder to binder solution and stir at 100-130℃ for 30-120 minutes; ③ Cooling and cake making: Pour the mixed slurry into a mold, let it cool naturally to room temperature, and demold to obtain a dense wax cake.

8. The method for preparing the novel talc ceramic material for hot pressing as described in claim 5, characterized in that, In step S5, the green blank is embedded in industrial alumina powder, placed in a dewaxing furnace, heated to 600°C at a rate of 0.2-1°C / min, held for 2-4 hours, and then heated to 900-1000°C at a rate of 0.5-2°C / min, held for 1-3 hours; wherein the particle size of the industrial alumina powder is 50-150 mesh.

9. The preparation method of the novel talc ceramic material for hot pressing as described in claim 5, characterized in that, Step S6 involves heating at a rate of 1-8 °C / min.

10. The method for preparing novel talc ceramic material for hot pressing according to claim 5 yields insulating sleeves for electronic components, ceramic bases for high-frequency connectors, or ceramic components for precision sensors.