Preparation method of high-strength thin-body ceramic material

Abstract

The invention relates to the technical field of preparation of a thin-body ceramic material, and particularly discloses a preparation method of a high-strength thin-body ceramic material, and the high-strength thin-body ceramic material comprises the following components in percentage by weight: 55 wt% of alpha-Al2O3 matrix powder, 20 wt% of Si O2, 10 wt% of t-ZrO2, 10 wt% of high-entropy oxide microspheres, and 5 wt% of silicon boride long fibers. According to the invention, the SiO2 and the rare earth stable ZrO2 jointly participate in sintering, so that the formation of a mullite phase and a ternary eutectic network structure is promoted. The reticular structure has good interface bonding force, can disperse an acting force concentration area and alleviate the stress concentration effect of a crack tip, so that the toughness and the thermal shock resistance are further improved. Spherical particles with uniform morphology are obtained through spray drying, so that high fluidity and compact accumulation of the powder can be realized; in the subsequent hot isostatic pressing process, the ceramic obtains approximate theoretical density in an isotropic high-pressure environment, internal pores and microcracks are eliminated, and the strength and the density are both improved.

Description

Technical Field

[0001] The invention belongs to the technical field of thin-body ceramic material preparation, and particularly relates to a method for preparing a high-strength thin-body ceramic material. Background Art

[0002] In fields such as aerospace, micro-electromechanical systems, and smart wearables, material performance requirements are becoming increasingly stringent. Materials must possess ultra-thin walls to achieve lightweight designs, while also possessing high strength, toughness, density, and excellent thermal shock and impact resistance to ensure long-term stable operation in complex and harsh environments. Thin-walled ceramic materials, due to their unique performance advantages, demonstrate tremendous potential for application in these fields.

[0003] However, the existing preparation technology of thin-walled ceramic materials still has many shortcomings. On the one hand, in terms of material composition design, traditional thin-walled ceramic materials often lack effective control of the microstructure. Most materials only use a single oxide matrix. During the high-temperature sintering process, the grains tend to grow abnormally and the grain boundaries migrate actively, resulting in the yield strength and flexural strength of the material being difficult to meet the needs of high-end applications. Moreover, there is insufficient research on the mechanism for inhibiting crack propagation, and there is a lack of effective reinforcing phases to improve the fracture toughness and impact resistance of the material. For example, when some thin-walled ceramic materials are subjected to external forces, cracks tend to expand rapidly and cannot effectively absorb crack energy, thereby causing sudden fracture of the material, seriously affecting its reliability and safety in use.

[0004] On the other hand, in terms of preparation technology, traditional methods have obvious defects. Solid-phase sintering is a commonly used process for preparing thin-bodied ceramics, but during the sintering process, due to the uneven deformation between the powder particles, residual stress concentration is easily generated, resulting in a large number of pores and microcracks inside the material, which not only reduces the density of the material, but also seriously affects the mechanical properties of the material. In addition, traditional processes make it difficult to achieve high fluidity and dense stacking of powders, making it difficult to control the shape of the prepared thin-bodied ceramic materials, and it is difficult to meet the requirements for ultra-thin wall thickness and precise shape. Moreover, thin-bodied ceramic materials prepared by traditional methods perform poorly in terms of thermal shock resistance. When experiencing rapid temperature changes, they are prone to cracks or even ruptures due to thermal stress, which limits their application in some environments with large temperature differences.

[0005] Therefore, it is of great practical significance to develop a method for preparing high-strength thin-walled ceramic materials that can maintain ultra-thin wall thickness while having high strength, high toughness, high density, and excellent thermal shock and impact resistance.

[0006] To this end, the present application proposes a method for preparing a high-strength thin-walled ceramic material to solve the above-mentioned problems. Summary of the Invention

[0007] The object of the present invention is to provide a method for preparing a high-strength thin-walled ceramic material to solve the problems raised in the above background technology.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A high-strength thin-walled ceramic material, comprising:

[0010] The high-strength thin-body ceramic material includes, by weight percentage: α-Al2O3 matrix powder: 55wt%, SiO2 (used to promote the formation of mullite phase): 20wt%, t-ZrO2 (rare earth stabilized, crack-resistant phase): 10wt%, high-entropy oxide microspheres (such as (Mg, Co, Ni, Cu, Zn)O): 10wt%, and boron silicon (B4C) long fibers: 5wt%.

[0011] A method for preparing a high-strength thin-walled ceramic material, characterized in that it includes the high-strength thin-walled ceramic material as described above, and further includes the following steps:

[0012] α-Al2O3 powder (55 wt%) and high entropy oxide microspheres (10 wt%) were mixed to obtain a composite matrix;

[0013] SiO2 (20 wt%) and rare earth stabilized t-ZrO2 (10 wt%) are added to the composite matrix to generate a mullite-Al2O3-ZrO2 fine-grained interaction structure at high temperature to obtain a precursor;

[0014] adding boron silicon long fibers (B4C, 5 wt%) into the precursor to enhance crack bridging to obtain a hybrid;

[0015] Atomizing and drying the mixture to prepare spherical particles with uniform morphology to obtain dry particles;

[0016] The dried particles are statically pressed into 0.6 mm thin sheets to maintain the thin body shape, thereby obtaining an unbisque fired green body;

[0017] biscuit-firing the green body at 1200° C. to remove organic components and preliminarily form a ceramic skeleton to obtain a skeleton member;

[0018] The skeleton component is placed in a hot isostatic pressing process at 1500° C. and 50 MPa in an argon environment to densify and stimulate the synergistic reinforcement of the high entropy phase and the fiber, thereby obtaining a high-strength thin-body ceramic product.

[0019] Preferably, the mixing of α-Al2O3 powder (55wt%) and high entropy oxide microspheres (10wt%) to obtain a composite matrix comprises: ball milling in an ethanol medium at a mass ratio of high entropy oxide microspheres: α-Al2O3 powder: ethanol = 3:1:1 at 300rpm for 4h, and passing through a 200-mesh sieve to obtain the composite matrix.

[0020] Preferably, SiO2 (20wt%) and rare earth stabilized t-ZrO2 (10wt%) are added to the composite matrix to generate a mullite-Al2O3-ZrO2 fine-crystalline interaction structure at high temperature to obtain a precursor, comprising: wet ball milling SiO2 and t-ZrO2 with the composite matrix in a mass ratio of 2:1 for 2 hours, followed by drying and crushing at 70°C to obtain a precursor.

[0021] Preferably, the boron silicon long fibers (B4C, 5wt%) are incorporated into the precursor to enhance the crack bridging effect to obtain a mixture, comprising: ultrasonically dispersing the B4C long fibers and stirring at 200 rpm for 30 minutes to uniformly distribute the B4C long fibers in the precursor to obtain the mixture.

[0022] Preferably, the mixture is atomized and dried to prepare spherical particles with uniform morphology to obtain dry particles, comprising: when the mixture is spray-dried, the slurry contains 5 wt% of an auxiliary agent, the inlet temperature is 180°C, the atomizing air flow is 0.8 MPa, and spherical particles with a diameter of 50-150 μm are obtained.

[0023] Preferably, the skeleton component is placed in a 1500°C, 50MPa argon environment for hot isostatic pressing treatment to densify and stimulate the synergistic reinforcement of the high entropy phase and the fiber to obtain a high-strength thin-walled ceramic product, including: hot isostatic pressing and heat preservation for 1 hour, then cooling to room temperature at a rate of 10°C / min to obtain a high-strength thin-walled ceramic product with a density of >99.5% and a thickness of 0.6mm.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention introduces high-entropy oxide microspheres into the matrix, allowing the ceramic to form a fine-grained structure with coexisting multiple oxide phases during high-temperature sintering. Different crystal phases are staggered at the grain boundaries, effectively preventing grain boundary migration and grain growth, thereby significantly improving the yield strength and flexural strength of the material. Boron silicon long fibers are dispersed within the matrix in a rod-like structure. Under external load, the fibers are the first to be encountered during crack propagation. The fibers absorb crack energy through bridging and pulling, and generate friction energy dissipation at the fiber-matrix interface, greatly improving fracture toughness and impact resistance.

[0026] (2) The SiO2 and rare earth stabilized ZrO2 of the present invention participate in sintering together, promoting the formation of mullite phase and ternary eutectic network structure. This network structure has good interfacial bonding force, can disperse the force concentration area, and alleviate the stress concentration effect at the crack tip, thereby further improving toughness and thermal shock resistance. Spherical particles with uniform morphology are obtained by atomization drying, which can achieve high fluidity and dense stacking of powder; the subsequent hot isostatic pressing process enables the ceramic to obtain near-theoretical density under an isotropic high-pressure environment, eliminating internal pores and microcracks, achieving a dual improvement in strength and density, and at the same time avoiding the residual stress concentration caused by uneven deformation during traditional solid-phase sintering.

[0027] (3) The thin-walled ceramics produced by the present invention can maintain ultra-thin wall thickness while being formed without sacrificing density and mechanical properties, meeting the dual demands of lightweight structure and high reliability in high-end fields such as aerospace, micro-electromechanical, and smart wearables. Through the synergistic effect of material microstructure regulation and advanced forming technology, not only the mechanical strength and toughness of thin-walled ceramics are significantly improved, but also the precise control of thin-wall shape and high densification requirements are taken into account. In theory, they have excellent impact resistance, thermal shock resistance, and long-term fatigue stability, and have good industrial feasibility and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flow chart of a method for preparing a high-strength thin-walled ceramic material according to the present invention. DETAILED DESCRIPTION

[0029] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] Example 1:

[0031] See also Figure 1 As shown, the micro UAV blade protection cover is prepared;

[0032] Material ratio (calculated based on a total of 100g)

[0033] α-Al2O3 powder: 55g

[0034] High entropy oxide microspheres (composition of about Mg 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O): 10g

[0035] SiO2 powder: 20g

[0036] Rare earth stabilized t-ZrO2 powder: 10g

[0037] Borosilicate long fiber (diameter 1–3 μm, length 50–100 μm): 5 g

[0038] Ethanol (ball milling medium): 45 mL

[0039] Spray aid (polyvinyl pyrrolidone solution, 5wt%): 5g dissolved in 95mL water

[0040] Preparation steps

[0041] Ball milling

[0042] 55 g of α-Al2O3, 10 g of high entropy oxide microspheres and 45 mL of ethanol were simultaneously placed into a ball mill jar containing zirconia balls. The ratio of high entropy oxide microspheres: α-Al2O3 powder: ethanol was 3:1:1.

[0043] The mixture was ball-milled at 300 rpm for 4 hours, taken out, passed through a 200-mesh sieve, and air-dried for later use.

[0044] Adding mullite phase and anti-cracking phase

[0045] The mixed powder was wet-ball milled with 20 g SiO2 and 10 g t-ZrO2 dry powder for 2 h (the ball: material: liquid ratio was the same as above), and then dried in an oven at 70°C for 4 h to form a uniform powder.

[0046] Long fiber dispersion

[0047] 5 g of B4C long fiber was first ultrasonically treated in 50 mL of deionized water for 15 minutes, and then the above dry powder was slowly added and stirred at a low speed of 200 rpm for 30 minutes until the fiber was evenly coated with the powder, and then dried at 70°C.

[0048] Atomization drying

[0049] The dry powder was suspended in an aqueous solution containing 5 wt% of a spray adjuvant (solid content of about 30 wt%) and a spray dryer was used with an inlet temperature of 180 °C and an atomization pressure of 0.8 MPa to collect spherical particles with a diameter of 50–150 μm.

[0050] Static pressure forming

[0051] 100 g of spherical particles were placed in a stainless steel mold with a diameter of 80 mm and a thickness of 0.6 mm, and a static pressure of 5 MPa was maintained for 2 minutes, and the green body was taken out.

[0052] Biscuit-fired additives

[0053] The green body was placed in air, heated to 1200°C at a rate of 5°C / min, kept warm for 2 hours, and naturally cooled to room temperature to remove organic matter such as polyvinyl pyrrolidone to obtain a porous skeleton.

[0054] Hot isostatic pressing densification

[0055] The bisque-fired part was placed in a HIP furnace, heated to 1500°C and filled with argon to 50 MPa. After keeping warm for 1 hour, the temperature was lowered to room temperature at a rate of 10°C / min to obtain a high-strength annular ceramic protective cover with a density of >99.5% and a thickness of 0.6 mm.

[0056] According to the material ratio prepared above, high-strength thin-film ceramics were prepared, with a final thickness of 0.6 mm;

[0057] Cut into an annular protective cover with a diameter of 80mm and an inner diameter of 60mm.

[0058] 2. Installation and usage scenarios

[0059] Installed on the outside of the micro-powered blades of a 200mm diameter quad-rotor drone, it protects against foreign object impact and falls.

[0060] Continuous flight for 2 hours in an outdoor wind speed of 5m / s.

[0061] 3. Performance Testing

[0062] Torque test: A desktop torque meter (model: TT-Q100) was used to measure the full-load torque change of the blade. The results showed that the maximum torque fluctuation was ≤2% (Table 1);

[0063] Impact resistance test: A 1J energy steel ball (20mm diameter) was applied to the center of the protective cover for 5 impacts. No obvious crack propagation was observed using SEM.

[0064] The torque stability test data is shown in Table 1 below:

[0065] Table 1

[0066] Number of tests Speed ​​(rpm) Torque (mN·m) Relative change (%) 1 4500 52.3 — 2 4500 51.8 -0.96 3 4500 52.1 -0.38 4 4500 52.5 +0.38 5 4500 52.2 -0.19

[0067] As can be seen above, the introduction of high-entropy oxide microspheres into the ceramic matrix allows the formation of a fine-grained structure with multiple oxide phases coexisting during high-temperature sintering. The interlaced distribution of different crystalline phases at the grain boundaries effectively prevents grain boundary migration and grain growth, significantly improving the material's yield strength and flexural strength.

[0068] Example 2:

[0069] Ultra-thin smart watch back panel preparation process

[0070] Material ratio (calculated based on a total of 100g)

[0071] α-Al2O3 powder: 55g

[0072] High entropy oxide microspheres: 10g

[0073] SiO2 powder: 20g

[0074] Rare earth stabilized t-ZrO2 powder: 10g

[0075] B4C long fiber: 5g

[0076] Ethanol: 45 mL

[0077] Spray aid (5wt% PVP aqueous solution): 5g

[0078] Preparation steps

[0079] Wet and dry ball milling

[0080] 55 g of α-Al2O3, 10 g of high entropy oxide and 45 mL of ethanol were ball-milled for 4 hours. After screening out large particles, 20 g of SiO2 and 10 g of t-ZrO2 were added and ball-milled for another 2 hours. The mixture was then dried at 70 °C.

[0081] B4C Fiber Treatment

[0082] The B4C fibers were ultrasonicated in deionized water for 15 min, then mixed with the dry powder, stirred at 200 rpm for 30 min, and dried again.

[0083] Preparation of atomized slurry

[0084] The powder was mixed with 5 wt% of spraying aid, the solid content was adjusted to 30 wt%, and the mixture was stirred evenly.

[0085] spray drying

[0086] The atomization conditions were the same as those in Example 1, and spherical powders with a diameter of 40–100 μm were obtained.

[0087] Mold forming

[0088] The powder was loaded into a mold with a diameter of 40 mm and a thickness of 0.6 mm, and a static pressure of 5 MPa was maintained for 2 minutes. The green sheet was then removed from the mold.

[0089] Go to organic biscuit

[0090] The temperature was raised to 1200°C at a rate of 5°C / min and kept at that temperature for 2 hours to remove the additives and perform preliminary curing.

[0091] HIP sintering

[0092] The ceramic back plate was hot isostatically pressed at 1500°C and 50 MPa argon for 1 hour and then cooled to obtain a dense, flat, 0.6 mm thick circular ceramic back plate.

[0093] Material ratio and preparation

[0094] Similarly, a 0.6 mm thick, 40 mm diameter disc was prepared and used as a watch back cover;

[0095] 2. Installation and usage scenarios

[0096] Assembled in a 42mm diameter smartwatch for daily wear;

[0097] Simulating daily user use: The wearer is subjected to five falls, five side falls, and five corner impacts from a height of 1.5m.

[0098] 3. Drop test

[0099] Test method: According to IEC 60068-2-32, use a drop tester (model: DT-LD10) and record the number of times without cracking.

[0100] Test results: After falling from the front, sides and corners, no cracks or fragments were found.

[0101] From the above, it can be seen that the long borosilicate fibers are dispersed in the matrix in a rod-like structure. Under the action of external load, the crack first encounters the fibers during propagation. The fibers absorb the crack energy through bridging and pulling, and generate friction energy consumption at the fiber-matrix interface, greatly improving the fracture toughness and impact resistance.

[0102] Comparative Example

[0103] Three-point bending strength and fracture toughness

[0104] 1. Sample Preparation

[0105] Five pieces (size 30×5×0.6 mm) of high-strength thin-body ceramics and five pieces of traditional pure Al2O3 thin-body ceramics (thickness 0.6 mm, prepared by conventional ball milling + sintering) were prepared.

[0106] 2. Test equipment and methods

[0107] Three-point bending: a universal material testing machine (Instron 3345) was used with a span of 20 mm and a loading rate of 0.5 mm / min to record the breaking load;

[0108] Fracture toughness: The SEVNB (single-edge V-notched beam) method was used to create a V-notch (depth 0.2 mm), and the fracture toughness (KIC) was calculated according to ASTM C1421.

[0109] 3. Data and Computing

[0110] Bending strength formula:

[0111] in

[0112] F: breaking load (N);

[0113] L: span (mm);

[0114] b: sample width (mm);

[0115] d: sample thickness (mm).

[0116] The three-point bending and fracture toughness test data are shown in Table 2 below:

[0117] Table 2

[0118]

[0119]

[0120] The present invention has high strength:

[0121]

[0122] The comprehensive comparison is shown in Table 3 below:

[0123] Table 3

[0124]

[0125] As can be seen from the above, SiO2 and rare earth-stabilized ZrO2 participate in sintering together, promoting the formation of mullite phase and ternary eutectic network structure. This network structure has good interfacial bonding, can disperse the stress concentration area, and alleviate the stress concentration effect at the crack tip, thereby further improving toughness and thermal shock resistance.

[0126] Spherical particles with uniform morphology are obtained through atomization drying, which can achieve high fluidity and dense stacking of the powder; the subsequent hot isostatic pressing process enables the ceramic to obtain near-theoretical density under an isotropic high-pressure environment, eliminating internal pores and microcracks, achieving a dual increase in strength and density, and at the same time avoiding the residual stress concentration caused by uneven deformation during traditional solid-phase sintering.

[0127] The thin-bodied ceramics produced by this method can maintain ultra-thin wall thickness (on the order of thousandths) and can be formed without sacrificing density and mechanical properties, meeting the dual needs of light and thin structure and high reliability in high-end fields such as aerospace, micro-electromechanical, and smart wearables.

[0128] Through the synergistic effect of material microstructure regulation and advanced molding technology, the present invention not only significantly improves the mechanical strength and toughness of thin-walled ceramics, but also takes into account the precise control of thin-wall shape and high densification requirements. In theory, it has excellent impact resistance, thermal shock resistance and long-term fatigue stability, and has good industrial feasibility and promotion value.

[0129] In the description of this specification, the reference terms "one embodiment", "some embodiments", "examples", "specific examples" or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0130] In the drawings of the embodiments disclosed in the present invention, only the structures related to the embodiments disclosed in the present invention are involved. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other.

[0131] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A high-strength thin-walled ceramic material, characterized in that: The high-strength thin-body ceramic material comprises, by weight percentage, 55 wt% of α-Al2O3 matrix powder, 20 wt% of SiO2, 10 wt% of t-ZrO2, 10 wt% of high-entropy oxide microspheres, and 5 wt% of boronized silicon long fibers.

2. A method for preparing a high-strength thin-walled ceramic material, characterized in that: The method further comprises the following steps: Mixing α-Al2O3 powder with high entropy oxide microspheres to obtain a composite matrix; adding SiO2 and rare earth stabilized t-ZrO2 into the composite matrix to generate a mullite-Al2O3-ZrO2 fine-grained interaction structure at high temperature to obtain a precursor; adding long silicon boride fibers into the precursor to enhance crack bridging to obtain a hybrid; Atomizing and drying the mixture to prepare spherical particles with uniform morphology to obtain dry particles; The dried particles are statically pressed into 0.6 mm thin sheets to maintain the thin body shape, thereby obtaining an unbisque fired green body; biscuit-firing the green body at 1200° C. to remove organic components and preliminarily form a ceramic skeleton to obtain a skeleton member; The skeleton component is placed in a hot isostatic pressing process at 1500° C. and 50 MPa in an argon environment to densify and stimulate the synergistic reinforcement of the high entropy phase and the fiber, thereby obtaining a high-strength thin-body ceramic product.

3. The method for preparing a high-strength thin-walled ceramic material according to claim 2, characterized in that: The method of mixing α-Al2O3 powder with high entropy oxide microspheres to obtain a composite matrix comprises: ball milling in an ethanol medium at a mass ratio of high entropy oxide microspheres: α-Al2O3 powder: ethanol = 3:1:1 at 300 rpm for 4 hours, and passing through a 200-mesh sieve to obtain the composite matrix.

4. The method for preparing a high-strength thin-walled ceramic material according to claim 2, characterized in that: The method comprises adding SiO2 and rare earth stabilized t-ZrO2 into the composite matrix to generate a mullite-Al2O3-ZrO2 fine crystal interaction structure at high temperature to obtain a precursor, comprising: wet-milling SiO2 and t-ZrO2 with the composite matrix in a mass ratio of 2:1 for 2 hours, followed by drying and crushing at 70°C to obtain the precursor.

5. The method for preparing a high-strength thin-walled ceramic material according to claim 2, characterized in that: The method of adding boron silicon long fibers into the precursor to enhance crack bridging to obtain a mixture comprises: ultrasonically dispersing the B4C long fibers and stirring at 200 rpm for 30 minutes to uniformly distribute the B4C long fibers in the precursor to obtain the mixture.

6. The method for preparing a high-strength thin-walled ceramic material according to claim 2, characterized in that: The mixture is subjected to atomization drying to prepare spherical particles with uniform morphology to obtain dry particles, comprising: when spray drying the mixture, the slurry contains 5wt% of an auxiliary agent, the inlet temperature is 180°C, the atomization air flow is 0.8MPa, and spherical particles with a diameter of 50-150μm are obtained.

7. The method for preparing a high-strength thin-walled ceramic material according to claim 2, characterized in that: The skeleton component is placed in a 1500°C, 50MPa argon environment for hot isostatic pressing treatment to densify and stimulate the synergistic strengthening of the high entropy phase and the fiber to obtain a high-strength thin-body ceramic product, including: hot isostatic pressing and heat preservation for 1 hour, then cooling to room temperature at a rate of 10°C / min to obtain a high-strength thin-body ceramic product with a density of >99.5% and a thickness of 0.6mm.

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