High-temperature-resistant high-toughness ceramic spring as well as preparation method and application thereof

Abstract

The invention provides a high-temperature-resistant high-toughness ceramic spring and a preparation method thereof. The ceramic spring comprises 100 parts by weight of silicon nitride and 4-28 parts by weight of zirconium boride or hafnium boride; and 1-15 parts by weight of a lanthanide oxide. The method comprises the following steps: 1) winding a gelled ceramic wire containing a solvent (I) and ceramic powder (II) on a mold for molding, and carrying out first-stage drying treatment under the condition of constant temperature and constant humidity of lower than 100 DEG C to obtain a preliminarily dried wound ceramic wire, the solvent (I) is a mixture of a water-soluble high-boiling-point organic solvent (such as butanediol) and water in a mass ratio of (0.005-1): 1; (2) the wound ceramic wire is subjected to second-stage drying at the temperature of 105-400 DEG C, then demolding is conducted, and a ceramic spring blank is obtained; (3) discharging glue and sintering to obtain a ceramic spring blank; and 4) carrying out pressure impregnation on the green body by using silicon halide, reacting with liquid ammonia or hydrated hydrazine hydrochloride, and carrying out high-temperature heat treatment in a nitrogen atmosphere to obtain the ceramic spring.

Description

Technical Field

[0001] This invention relates to the field of ceramic spring technology, and more specifically, to a high-temperature resistant, high-strength, and high-toughness ceramic spring and its preparation method. Background Technology

[0002] With the development of aerospace technology, higher requirements have been placed on the temperature resistance and high reliability of temperature-resistant components. At present, traditional metal and high-temperature alloy springs have low temperature resistance and are prone to oxidation and corrosion in service conditions, making it difficult to meet application requirements. Ceramic springs have become a research focus.

[0003] CN1152299A discloses a high thermal conductivity silicon nitride sintered body: containing more than 7.5 wt% but less than 17.5 wt% of rare earth elements (converted to oxides), and a total of less than 0.3 wt% of Li, Na, K, Fe, Ca, Mg, Sr, Ba, Mn, and B as impurity cations, with a thermal conductivity of 80 W / m·K or higher. It may also, as needed, incorporate at least one of the following groups selected from aluminum nitride, alumina, or oxides, carbides, nitrides, silicides, and borides of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W, each in a predetermined amount, into fine, high-purity silicon nitride powder. The body consists of silicon nitride crystals and grain boundary phases, with the ratio of crystalline compounds in the grain boundary phase to the total grain boundary phase being 20% ​​or more. Alternatively, the thermal conductivity may also be greater than 80 W / m·K. The silicon nitride ceramics described are mainly used to prepare high thermal conductivity materials. Their high thermal conductivity is the key to the CN1152299A patent. However, the toughness of the high thermal conductivity silicon nitride sintered body is not disclosed in the paper. Moreover, the toughness of the sintering system in the prior art CN1152299A is lower than that of this patent, and it cannot be applied to the research of ceramic spring materials.

[0004] CN109867527A discloses a method for preparing a photopolymer 3D printed spiral ceramic spring: Preparation of photosensitive ceramic slurry: Surface-modified ceramic powder, photosensitive resin, and diluent are added to a ball mill jar for planetary ball milling and mixing to prepare the slurry. The slurry is then filtered, vacuum stirred, and degassed before use. Design and slicing of a three-dimensional digital model; Preparation of the ceramic spring blank: The prepared photosensitive ceramic slurry is poured into the feed tank of a photopolymer 3D ceramic printer. The sliced ​​digital model is imported into the execution software to start printing. Process parameters are adjusted and optimized to print a combined blank of the ceramic spring and its support. Post-processing of the ceramic spring blank: The combined blank of the ceramic spring and its support is ultrasonically cleaned to remove the slurry adhering to the surface, then UV cured for 3-5 minutes to improve the mechanical strength of the blank. The spring blank and support blank on the combined blank are separated by rotation, polished, and coated with a layer of alumina powder. Then, the spring blank and support blank are reassembled by rotation for use. Adhesive removal; Sintering. Photopolymer 3D printing produces helical ceramic springs for high-Mach aircraft. The method involves photopolymer 3D printing to create a preform combining the ceramic spring and its support structure. In subsequent processes, the support structure needs to be removed. However, spring performance is related to the overall integrity of the spring; separating the support structure by rotation can leave surface defects, affecting spring performance and reducing reliability. This patent utilizes integrated gel filament molding to reduce surface defects and improve reliability.

[0005] CN102757221A discloses a manufacturing method for a spiral ceramic spring: 1. Raw material preparation: Mixing partially stabilized zirconia (PSZ) powder or silicon nitride powder, nano-additives, and water, adding a dispersant, and grinding and mixing in a stirred mill to prepare a slurry; drying the uniformly mixed slurry and then pulverizing it to obtain raw material powder for molding; 2. Molding: Adding water to the raw material powder to prepare a slurry, adding a binder and mixing uniformly, preparing granules by spray drying, loading the granules into a cylindrical rubber mold, and preparing a cylindrical green body by isostatic pressing; 3. Firing: Firing the cylindrical green body at 1100-1400℃. 4. Processing: According to the spring design requirements, the round tube-shaped spring blank is processed into a spiral shape using a wire saw or lathe tool. The helix angle of the spiral is determined according to the helix angle of the final spring product. The edges of the spring wires of the processed spring blank are polished with fine sandpaper or mortar to form rounded corners. 5. High-temperature sintering: The spring blank is inserted into a ceramic core rod support and placed in a sagger for suspension firing. The firing temperature and atmosphere are: zirconia ceramic springs are sintered at 1400-1600℃ in an air atmosphere. 6. Edge grinding and polishing: The sintered ceramic spring is separated from the core rod, and the upper and lower end faces of the spring are ground flat. The surface of the spring wires is polished to obtain the finished product. Spiral ceramic springs are used in cutting-edge fields or special industries such as new energy, national defense, aerospace, chemical industry, semiconductor, and rail transportation. The ceramic springs are made by machining ceramic tubes, which consumes a lot of raw materials during the processing, resulting in material waste and easily introducing processing defects.

[0006] CN1472448A discloses a method for producing nano-ceramic springs: using nano-grade ZrO2 powder as raw material, adding premixed liquid and grinding and mixing in a ball mill to prepare a slurry; after vacuum degassing the prepared slurry, adding an initiator, and then injecting it into a spring mold; after the slurry solidifies, demolding, drying in an oven at 50-120℃ for 0.5-3 hours, and then naturally cooling to obtain a spring blank; heating the naturally cooled spring blank in a resistance furnace to 700-1200℃ and holding for 0.5-2 hours to remove the binder, and then naturally cooling; impregnating the impregnated and naturally cooled spring blank with a slurry of 30-70wt% for 10-30 minutes; placing the impregnated and densed spring blank in a support and embedded powder, placing it in a sintering furnace and heating to 1400-1700℃, holding for 0.5-3 hours for pressureless winding to obtain the finished product. The ceramic spring is formed in one piece. When the ceramic spring blank is demolded, the blank is still in a soft state. Demolding is easy to deform and cause changes in the spring structure.

[0007] CN115256990A discloses a method for preparing low-resin mica tape using hot pressing. This method involves preparing an adhesive compound using epoxy resin and hyperbranched polyester resin, diluting a portion of the compound to obtain a diluted adhesive compound, and then treating reinforcing fiber fabric and reinforcing fiber monofilaments separately with a silicon chloride-acetone solution to obtain modified reinforcing fiber fabric and modified reinforcing fiber monofilaments. Silicon chloride is then added to the diluted adhesive compound to impregnate the modified reinforcing fiber fabric, obtaining a reinforcing material layer. Simultaneously, modified reinforcing fiber monofilaments are added to the base adhesive compound to obtain an adhesive. The adhesive is coated onto one or both sides of a mica paper substrate to obtain an adhesive layer. A reinforcing material layer is then laid flat on the adhesive layer surface, and the substrate is subjected to two roll pressings, followed by drying, slitting, and winding to obtain the finished low-resin mica tape. The mica tape prepared by this method has a low adhesive content and excellent VPI (Vacuum-Insulated Printed Polymer) process performance. The aforementioned patent uses an impregnation process to modify fibers, which differs from this patent. This patent uses impregnation to immerse silicon halides into the ceramic spring blank, and after subsequent sintering, it can improve the density of the spring.

[0008] CN115417685A discloses a SiC / Si3N4 composite with electromagnetic wave absorption properties and its preparation method. The SiC / Si3N4 composite includes a SiC fiber preform woven from SiC fibers; a BN interface layer prepared and deposited on the surface of the SiC fibers via chemical vapor infiltration (CVI); a silicon-based ceramic prepared on the surface of the BN interface layer via a precursor impregnation pyrolysis (PIP) process; and a Si3N4 matrix prepared and deposited on the surface of the silicon-based ceramic via a PIP process. In the SiC / Si3N4 composite provided by this invention, the silicon-based ceramic, acting as a protective layer, is located between the BN interface layer and the Si3N4 matrix, protecting the BN interface layer and ensuring its integrity and continuity on the outside of the SiC fibers. The silicon-based ceramic is prepared via a precursor impregnation pyrolysis (PIP) process. During the PIP process, pores and cracks exist within the silicon-based ceramic. These cracks and pores can guide multi-directional deflection of cracks during propagation, giving the composite high toughness. The aforementioned patent also employs fiber impregnation and pyrolysis to increase the density of fiber composite materials, but uses different materials. The patent uses any one of the following matrices: SiBCN obtained from the pyrolysis of the ceramic precursor polyborosilicate (PBSN), SiOC obtained from the pyrolysis of the ceramic precursor polysiloxane (PSO), or SiCN obtained from the pyrolysis of the ceramic precursor polynitrosilane (PSN). This patent uses silicon halides to pressure-impregnate the debinding and sintered ceramic spring blank to increase the density of the ceramic spring, making it more suitable for preparation using this patent.

[0009] CN114773082A discloses a symmetrical continuous gradient structure silicon nitride ceramic radome and its preparation method. The steps are as follows: (1) electromagnetic performance simulation and broadband transmission performance optimization of the radome are performed using electromagnetic simulation software CST; (2) a porous silicon nitride-based ceramic core layer is prepared using gel casting-precursor impregnation pyrolysis method; (3) silicon nitride nanowires are prepared on the surface of the core layer using carbothermal reduction nitridation / silicon powder nitridation / catalytic pyrolysis method; (4) the surface of the radome containing nanowires is densified using chemical vapor deposition / infiltration method; (5) the radome is precision machined. The technical solution provided by this invention is a combined process, which can achieve synergistic improvement of broadband transmission, high temperature bearing capacity and environmental erosion resistance of high-performance radomes, as well as near-net-shape integrated molding of large and complex continuous gradient structure radomes. It solves the current problem of difficult molding of gradient structure radomes and realizes continuous change of radome structure and performance gradient. The aforementioned patent involves densifying the surface of the radome, preventing the impregnation process from penetrating into the interior of the blank. In contrast, this patent allows the impregnation process to penetrate into the interior of the blank, increasing its strength.

[0010] CN115141015A discloses a ceramic spring and its preparation method. The ceramic spring is prepared from the following raw materials in parts by weight: 53.3-78 parts ceramic powder, 15-30 parts water, and 4.2-8.5 parts of a mixture of methylcellulose, sodium carboxymethylcellulose, hydroxypropyl methylcellulose, and polyvinyl butyral. The ceramic powder, water, and at least one of the following mixtures are mixed: methylcellulose, sodium carboxymethylcellulose, hydroxypropyl methylcellulose, and polyvinyl butyral. During the dehydration process, the wire length is reduced by 10-20%. After plasticizing, the spring blank is dried again and subjected to isostatic shrinkage. This avoids direct shrinkage during drying, which could lead to deformation and cracking due to a mismatch between the shrinkage amount and the spring's plasticity. This method effectively reduces the deformation and cracking of the ceramic spring caused by spring shrinkage during sintering.

[0011] CN110937909A discloses a method for preparing a continuous fiber-reinforced C / SiC ceramic spring. A dedicated mold structure is designed, and a 3D-printed, openable, threaded cylindrical mold with through-holes distributed between the threads is obtained. The mold is divided into three axial sections, with the central mold longer than the two end molds. A spring preform is prepared using this mold, and the spring preform is toughened using chemical vapor infiltration, followed by the deposition of a SiC matrix and coating. This invention starts with the design of the carbon fiber weave structure to control the shear strength of the spring wires, achieving designability of the spring's rebound force and stiffness. Furthermore, the controllability of the spring's rebound force, stiffness, and fatigue resistance is achieved through a uniform and precisely controllable interface layer and coating thickness. The ceramic matrix composite spring prepared by this invention can retain up to 97.6% of its stiffness at 1000℃. Specifically, it involves the reinforcement, toughening, and molding of carbon fibers, and its main application is in the field of high-temperature sliding seals. The patented method uses ceramic fiber impregnation and pyrolysis to prepare ceramic springs, but these ceramic springs have weak oxidation resistance and cannot be used for extended periods at high temperatures.

[0012] CN112225556A discloses a method for producing a helical superconducting ceramic compression spring, comprising: 1. mixing ceramic powder, an organic material for molding, and water to form a mixture; the organic material for molding is methylcellulose or polyvinyl butyral, with a mass ratio of 3.1%-6.2%, used as a binder; the ceramic powder is zirconium oxide powder, silicon nitride powder, silicon carbide powder, or a mixture of silicon nitride powder and silicon carbide powder, with a mass ratio of 61.9%-77.2%; sintering aids, also known as..., may be added to the ceramic powder. The process involves several steps: 1. Adding sintering aids, such as oxides or non-oxides added during ceramic sintering to promote densification, like CaO and TiO2, MnO and TiO2, SiO2 and CaO, Y2O3 and Al2O3, MgO and CeO, etc.; 2. Extruding the mixture into wire; 3. Drying the wire; 4. Immersing the dried wire in an organic solvent for plasticization; the organic solvent is one or a mixture of two or more of ethanol, acetone, trichloroethylene, and tetrachloroethylene; 5. Winding the plasticized wire into a coil; 6. Sintering the coil at high temperature. The described spiral superconducting ceramic compression spring is used in extreme working conditions in chemical, defense, and aerospace fields, such as high temperature, strong electric field, strong magnetic field, and acidic or alkaline environments. The patented method uses extrusion molding to prepare the ceramic spring, but the spring's performance stability is poor.

[0013] CN115849916A discloses a method for preparing a ceramic spring, comprising the following steps: preparing ceramic clay, the ceramic clay comprising silicon nitride ceramic powder, binder, and plasticizer; preparing a ceramic spring blank from the ceramic clay; preparing a ceramic impregnation liquid, the ceramic impregnation liquid comprising toughened ceramic powder; impregnating the ceramic spring blank in the ceramic impregnation liquid to obtain a ceramic spring body; removing the binder from the ceramic spring body under nitrogen or an inert atmosphere, and sintering after the binder removal is completed to obtain a ceramic spring; thereby achieving that the ceramic spring has both high strength and high toughness, and can be used as a sealing material for solid oxide fuel cells. The patent uses an extrusion molding process to prepare the ceramic spring. During the clay mixing process, some pores remain in the clay body. Impregnation reduces the pore volume, but some pores still exist, forming point defects and reducing the batch stability of the ceramic spring.

[0014] CN106904949A discloses a novel method for preparing high-hardness ceramic micro-spring materials, comprising two steps: silicon nitride material preparation and ceramic spring material preparation. The process described in this invention breaks away from the material and mold limitations of current micro-spring processing technologies, innovatively using ceramic metal materials as raw materials, and pressing the raw material powder into the corresponding micro-spring shape under high pressure, which greatly improves the hardness and bending strength of the micro-spring products. Specifically, a method for preparing high-hardness ceramic microspring materials is disclosed, comprising two steps: preparation of silicon nitride material and preparation of ceramic spring material: 1. Preparation of silicon nitride material: Silicon powder and silicon dioxide powder are mixed in a molar ratio of 1:1, and then reduced iron powder, accounting for approximately 10-20% of the total mass of the solid mixture, is added. The mixture is then calcined in a tube furnace at a heating rate of 6-8℃ / min and a holding time of 2-4h. After cooling, the solid particles are collected. 2. Preparation of ceramic spring material: 20-40 parts of silicon nitride material, 1-5 parts of silicon dioxide, 40-50 parts of alumina, and 1-5 parts of polyvinyl alcohol are mixed and pressed into the required microspring shape. The mixture is then dried for 12-36h, and the dried material is sintered in a furnace at 1500-2000℃ for 1-5h to obtain high-hardness ceramic microspring material. This material is used in microsprings.

[0015] CN109867526A discloses a method for preparing high-temperature ceramic springs. This method uses high-purity silicon nitride as the main raw material and a certain type of silicone rubber as a molding agent. The process involves mixing, molding, and sintering to prepare the high-temperature ceramic springs. The specific process is as follows: raw material preparation → mixing → homogenization → molding → curing → firing → slurry impregnation → sintering → finished product. The raw material preparation involves mixing high-purity silicon nitride and sintering aids, including alumina and yttrium oxide, using anhydrous ethanol as the dispersion medium in a planetary mill. The molding agent used in the mixing process is room-temperature vulcanized methyl silicone rubber, the crosslinking agent is tetraethyl orthosilicate, and the catalyst is an organotin compound. Molding involves placing the homogenized material into an extrusion die and extruding it at a certain speed into a circular wire of the required specifications. The extruded wire is then wound onto a winder (i.e., a spring winding die) of the corresponding specifications to form a spring shape. This method is used to prepare silicon nitride ceramic springs with operating temperatures exceeding 1000℃. The ceramic spring is prepared by extrusion molding. The extrusion molding process easily introduces pore defects into the ceramic clay, and the pores are not further treated afterward, which increases the instability of the spring.

[0016] CN1775708A discloses a semi-aqueous injection molding gel method for precision molding of ceramic green bodies by adding alcohols. The method includes: accurately weighing various ceramic powders; weighing water and a water-soluble organic solvent according to a specified ratio, wherein the organic solvent is a mixture of methanol, ethanol, ethylene glycol, glycerol, or one or more substances, with a ratio of 0.05:1 to 1:1 with water; weighing 0.2-2% by weight of one of polyacrylate, polymethacrylate, carboxylate, or citrate as a dispersant; weighing a water-soluble acrylamide or methacrylamide organic monomer and a methylenebisacrylamide or polyethylene glycol dimethacrylate crosslinking agent, with a ratio of organic monomer to crosslinking agent between 10:1 and 30:1, and the total amount added being 10-30% of the total amount of water and alcohol solvent; then mixing and ball milling; degassing; adding a catalyst or reducing agent; adding an initiator; injection molding gel; demolding and drying. This patent proposes a new semi-aqueous injection-gel molding technology for ceramic green bodies. It achieves precise injection-gel molding of the green body without affecting the solid content and gelation of the slurry, simplifies the dehydration and drying process, ensures thorough removal of moisture and organic solvents, avoids the risk of cracking during the drying and sintering of large-sized ceramic parts, eliminates the need for defoamers, and results in green bodies with good machinability. The advantages of this patented method are: low water consumption, thorough removal of organic matter, reduced green body shrinkage, and avoidance of cracking risks during the drying process for larger ceramic green bodies. Furthermore, the gelled green body exhibits better machinability before the removal of solvents such as ethylene glycol and glycerol. However, the density, surface smoothness, dimensional error, batch stability, and overall performance of the patented product still require further improvement.

[0017] CN2656711Y discloses a ceramic spring forming mold including a flexible inner mold (1) and two outer molds (2); the flexible inner mold is a hollow, closed columnar body with an inner mold spiral groove (3) on its outer wall, which matches the shape of the ceramic spring to be made, and the inner mold also has air holes (4); the two outer molds are symmetrical semi-circular rings, and their combined inner diameter matches the outer diameter of the inner mold, and their inner walls are provided with outer mold spiral grooves (5), which match the inner mold spiral grooves, and semi-circular bottom surfaces (7) can also be provided at the bottom ends of the two outer molds, forming a combined bottom surface; an upward grouting groove (6) is opened on the inner wall of one of the outer molds, corresponding to the position of the uppermost outer mold spiral groove, and its lower end is connected to the uppermost outer mold spiral groove, and its upper end extends out of the upper end surface of the outer mold. The patent discloses a ceramic spring mold. The ceramic springs produced by this mold will have mold merging marks on their surface. Removing these marks through processing can easily introduce processing defects, affecting the spring's performance.

[0018] CN106588000A discloses a manufacturing process for a helical ceramic spring, including steps such as slurry preparation, degassing, phase transformation molding, impregnation, drying, and sintering. The helical ceramic spring is prepared by using a rope-like effect-assisted phase transformation method. Specifically, a method for preparing a spiral ceramic spring is disclosed: ceramic powder is added to an organic solvent, ultrasonically treated for 15-30 minutes, an organic binder is added, and mechanically stirred under oil bath heat preservation; the resulting slurry is vacuum degassed and allowed to stand for 6-12 hours to form a spinning solution (2); the spinning solution is pushed into a discharge tank (3) by an injection pump (1), and then enters a coagulation bath (5) at a certain flow rate from a circular discharge port at the bottom of the discharge tank. The distance between the discharge port and the coagulation bath is controlled by a support frame. When the slurry comes into contact with the coagulation bath, a rope-winding effect and phase transformation occur, generating a precursor with a spiral structure; the prepared ceramic spring precursor is immersed in the coagulation bath for 24-48 hours to allow the phase transformation to proceed fully; the ceramic spring precursor is naturally dried for 24-48 hours under normal temperature and pressure conditions, and then inserted into a corundum tube and sintered in a muffle furnace under an air atmosphere. The ceramic powder includes yttrium-stabilized zirconia powder, alumina powder, cerium oxide powder, or silicon nitride powder, with an average particle size of 0.02-2 μm. Compared with existing technologies, this invention overcomes the shortcomings of existing methods, such as high material consumption, high production costs, and limited applicable material range. The produced ceramic springs can be used in many fields such as electrode insulation, heat insulation protection, and high-temperature spring components. The patented method uses a rope-effect material to prepare ceramic springs, but it cannot guarantee the theoretical structure of the ceramic spring, and can only form a helical structure.

[0019] The aforementioned CN2656711Y uses a molding die consisting of a flexible inner mold and two outer molds to form a ceramic spring. However, due to low molding precision, the spring surface exhibits problems such as non-density and high roughness. The aforementioned CN106588000A uses a rope-effect assisted phase transformation method to prepare a helical ceramic spring, but the ceramic springs prepared by this process have large dimensional errors and poor batch stability.

[0020] Therefore, how to prepare ceramic springs with high density, high surface smoothness, small dimensional error, good batch stability, and good overall performance has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0021] This invention provides a high-temperature resistant, high-strength and high-toughness ceramic spring (product or material) and its preparation method, aiming to solve the problems of low density, large roughness, large dimensional error, poor batch stability and poor overall performance of ceramic springs prepared by existing methods.

[0022] According to the first aspect of the present invention, a high-temperature resistant and high-strength ceramic spring (or sintered body) (i.e., ceramic product or material) is provided, which has high density, smooth surface, excellent dimensional stability (creep resistance), and good mechanical properties (elasticity and shape recovery properties) and high-temperature resistance, that is, the mechanical properties (e.g., elasticity) and high-temperature resistance are optimized.

[0023] The ceramic spring comprises (or contains) the following components or is (mainly) composed of the following components:

[0024] (1) 100 parts by weight of silicon nitride,

[0025] (2) 4-28 parts by weight, preferably 5-25 parts by weight, more preferably 6-24 parts by weight, more preferably 7-23 parts by weight, more preferably 8-22 parts by weight, more preferably 9-21 parts by weight, more preferably 10-20 parts by weight, more preferably 11-19 parts by weight, more preferably 12-18 parts by weight, more preferably 13-17 parts by weight (e.g., 14, 15 or 16 parts by weight) of a boride, wherein the boride is selected from one or more (e.g., three or four) of zirconium boride, titanium boride, tantalum boride, and hafnium boride; and

[0026] (3) 1-15 parts by weight, preferably 1.5-13 parts by weight, preferably 2-10 parts by weight, preferably 3-9 parts by weight, preferably 4-8 parts by weight, preferably 5-7 parts by weight (e.g. 5.5 or 6 or 6.5 parts by weight) of sintering aid containing lanthanides, wherein the sintering aid containing lanthanides is an oxide of lanthanides.

[0027] The sum of the weights of the above components (1), (2) and (3) is 92-100 wt%, preferably 93-99.9 wt%, preferably 93.5-99.8 wt%, more preferably 94-99.7 wt%, more preferably 94.2-99.6 wt%, more preferably 94.5-99.5 wt%, more preferably 94.7-99.4 wt%, more preferably 95-99.3 wt%, more preferably 95.2-99.2 wt%, more preferably 95.4-99.1 wt%, more preferably 95.5-99.0 wt%, for example 95.7, 96, 96.2, 96.5, 96.7, 97, 97.2, 97.5, 97.7, 98, 98.2, 98.5, 98.7, 99 wt%, based on the total weight of the ceramic spring. The balance consists of impurities and / or oxides of other metals (e.g., alkali metals), such as oxides of impurity metal elements Li, Na, K, Fe, Ca, Mg, Sr, and Ba (hereinafter referred to as impurities). The fewer impurities in a ceramic spring, the smoother its surface, and the higher its elasticity and bending strength. For example, when a small amount of MgO impurity is present in a ceramic spring, it affects the crystal structure of the ceramic spring, leading to a significant decrease in surface smoothness (significantly increased roughness) and a reduction in its elasticity and bending strength.

[0028] Preferably, the ceramic spring is a helical spring, a beveled spring, a cylindrical spring, a conical spring, a leaf spring, or a disc spring.

[0029] The content of the above component (1) refers to the silicon content converted to silicon nitride, or the silicon content calculated according to silicon nitride.

[0030] The content of the above component (2) refers to the content of borides converted into zirconium boride, titanium boride, tantalum boride and / or hafnium boride, or the content of borides calculated according to zirconium boride, titanium boride, tantalum boride and / or hafnium boride.

[0031] The content of the above component (3) refers to: the content of the sintering aid containing lanthanides converted into oxides of lanthanides, or the content of the sintering aid containing lanthanides calculated according to oxides of lanthanides.

[0032] Preferably, the oxides of the lanthanides are selected from one or two or more (e.g., three, four, five or six) of lanthanum oxide, ytterbium oxide, erbium oxide, neodymium oxide, lutetium oxide and cerium oxide.

[0033] In ceramic springs composed of silicon nitride and specific amounts of zirconium boride and / or hafnium boride and specific amounts of rare earth element oxides, a special crystalline phase-grain boundary phase structure can be formed, which is beneficial to reducing the surface roughness of the ceramic spring, improving its bending strength, and achieving a good balance between rigidity and toughness.

[0034] When the content of boride in component (2) is less than 3 parts by weight, the disadvantage is that the spring still has a certain elasticity at room temperature, but as the temperature rises, the low-boron spring material cannot withstand the high-temperature oxidation environment in an oxygen environment, resulting in oxidation of the spring and a significant reduction in spring performance. When the content of component (2) is higher than 30 parts by weight, the disadvantage is that the material hardness and bending strength increase, while the fracture toughness decreases, resulting in an increase in the hardness and stiffness of the ceramic spring, but a decrease in the compression. This invention, by selecting a suitable boride content, makes the resulting ceramic spring have good surface smoothness, as well as suitable stiffness, elasticity and high-temperature resistance.

[0035] When the content of sintering aid containing lanthanides in component (3) is less than 1 part by weight, the disadvantage is that during the sintering process, insufficient sintering aid cannot form a sufficient liquid phase, leading to unstable phase transformation of silicon nitride material and uneven silicon nitride grain size after sintering, affecting spring performance. When the content of component (3) is higher than 16 parts by weight, the disadvantage is that there is too much glass phase inside the spring. At high temperature, the glass phase reforms into a liquid phase, the spring softens, and creep occurs. This invention, by selecting appropriate sintering aid type and content, enables the obtained ceramic spring to have good surface smoothness and high strength properties.

[0036] Preferably, the boride is a mixture or combination of any two or more of zirconium boride, titanium boride, tantalum boride, and hafnium boride, such as a mixture or combination of any two (e.g., zirconium boride and hafnium boride) in a weight ratio of 1-2:1 (e.g., 1.5:1). Preferably, compared to containing only one boride, a mixture of two or more borides, such as a mixture of zirconium boride and hafnium boride in a weight ratio of 1-2:1 (e.g., 1.5:1), can improve the surface smoothness and gloss of the ceramic spring, increase its relative density, and improve its high-temperature resistance.

[0037] According to a second aspect of the present invention, a method for preparing the above-mentioned high-temperature resistant and high-strength ceramic spring or a method for preparing a high-temperature resistant and high-strength ceramic spring is provided.

[0038] Firstly, in the first sub-scheme of the second aspect of the present invention, a method for preparing a ceramic spring is provided, wherein the ceramic spring is a helical spring, the method comprising the following steps:

[0039] 1) A gelled ceramic wire containing solvent (I) and ceramic powder (II) (i.e., prepared from solvent I and ceramic powder II) is wound onto a mold for forming to obtain a ceramic spring wet blank. The wet blank is subjected to a first-stage drying treatment (e.g., 2-20 hours, such as 4-18 hours, 6-16 hours, or 8-14 hours) under constant temperature and humidity conditions below 100°C (to remove some or most of the water from the wire) to obtain a preliminarily dried wound ceramic wire.

[0040] Wherein, the solvent (I) is a mixture or combination of water and a water-soluble high-boiling-point organic solvent, wherein the boiling point of the water-soluble high-boiling-point organic solvent at 1 standard atmosphere is (at least) 20°C higher than the boiling point of water (100°C) (e.g., at least 20°C), that is, the boiling point of the water-soluble high-boiling-point organic solvent at 1 standard atmosphere is higher than 120°C; for example, the water-soluble high-boiling-point organic solvent is 1,3-butanediol or 1,4-butanediol;

[0041] In solvent (I), the mass ratio of the water-soluble high-boiling-point organic solvent to water is 0.005-1:1, preferably 0.0055-0.9:1, preferably 0.006-0.8:1, preferably 0.0065-0.7:1, preferably 0.007-0.6:1, preferably 0.0075-0.5:1, preferably 0.008-0.4:1, preferably 0.0085-0.3:1, preferably 0.009-0.2:1, preferably 0.0095-0.1:1, preferably 0.01-0.08:1, preferably 0.01-0.065:1, preferably 0.01-0.05:1;

[0042] 2) The preliminarily dried wound ceramic wire (together with the mold) obtained in step 1) above is subjected to a second stage of drying at a temperature of 105-400°C (e.g., 10-24 hours) (to remove water-soluble organic solvents and residual moisture from the wire, i.e., to remove water-soluble organic solvents and residual water, for example, by drying in an oven), and then the mold is removed to obtain a ceramic spring blank.

[0043] 3) The (spiral) ceramic spring blank was debonded and then sintered to obtain a debonded and sintered ceramic spring blank;

[0044] 4) The sintered ceramic spring blank is pressure-impregnated with silicon halides to allow the silicon halides to penetrate into the sintered ceramic spring blank. Then, it is placed in liquid ammonia or hydrated hydrazine hydrochloride for reaction, so that the silicon halides that have penetrated into the ceramic spring blank react to form iminosilicon precipitate. After the reaction is completed, the ceramic spring blank is placed in a sintering furnace and subjected to high-temperature heat treatment in an inert atmosphere (e.g., nitrogen atmosphere), for example, at a temperature of 800-1300℃ (preferably 900-1250℃, preferably 950-1230℃, preferably 1000-1200℃) to obtain the ceramic spring.

[0045] Secondly, in a second sub-scheme of the second aspect of the present invention, a method for manufacturing a ceramic spring is provided, wherein the ceramic spring is a ceramic leaf spring, the method comprising the following steps:

[0046] 1) A gelled ceramic sheet containing solvent (I) and ceramic powder (II) is placed on a ceramic mold for forming a leaf spring to obtain a wet ceramic spring blank. The wet blank is subjected to a first-stage drying treatment (e.g., 2-20 hours, such as 4-18 hours, 6-16 hours, or 8-14 hours) under constant temperature and humidity conditions below 100°C to obtain a preliminarily dried curved ceramic sheet.

[0047] Wherein, the solvent (I) is a mixture or combination of water and a water-soluble high-boiling-point organic solvent, wherein the water-soluble high-boiling-point organic solvent has a boiling point higher than 120°C at 1 standard atmosphere; preferably, the water-soluble high-boiling-point organic solvent is butanediol, more preferably 1,3-butanediol or 1,4-butanediol.

[0048] In solvent (I), the mass ratio of the water-soluble high-boiling-point organic solvent to water is 0.005-1:1, preferably 0.0055-0.9:1, preferably 0.006-0.8:1, preferably 0.0065-0.7:1, preferably 0.007-0.6:1, preferably 0.0075-0.5:1, preferably 0.008-0.4:1, preferably 0.0085-0.3:1, preferably 0.009-0.2:1, preferably 0.0095-0.1:1, preferably 0.01-0.08:1, preferably 0.01-0.065:1, preferably 0.01-0.05:1;

[0049] 2) The preliminarily dried curved sheet (together with the mold) obtained in step 1) above is subjected to a second stage of drying at a temperature of 105-400℃ to obtain a ceramic leaf spring blank;

[0050] 3) The ceramic leaf spring blank is debonded, then sintered, and then demolded to obtain the debonded and sintered ceramic spring blank;

[0051] 4) The ceramic leaf spring blank after debinding and sintering is pressure-impregnated with silicon halides to allow the silicon halides to penetrate into the ceramic leaf spring blank after debinding and sintering. Then, it is placed in liquid ammonia or hydrated hydrazine hydrochloride for reaction, so that the silicon halides that have penetrated into the ceramic leaf spring blank react to form iminosilicon precipitate. After the reaction is completed, the ceramic leaf spring blank is placed in a molding mold and then placed in a sintering furnace for high-temperature heat treatment in an inert atmosphere (e.g., nitrogen atmosphere), for example, heat treatment at a temperature of 800-1300℃ (preferably 900-1250℃, preferably 950-1230℃, preferably 1000-1200℃). Then, it is demolded to obtain the ceramic leaf spring.

[0052] Furthermore, in a third sub-scheme of the second aspect of the present invention, a method for manufacturing a ceramic spring is provided, wherein the ceramic spring is a ceramic disc spring, the method comprising the following steps:

[0053] 1) A gelled concentric ceramic sheet containing solvent (I) and ceramic powder (II) is placed in a disc spring mold to obtain a wet ceramic spring blank. The wet blank is subjected to a first-stage drying treatment (e.g., 2-20 hours, such as 4-18 hours, 6-16 hours, or 8-14 hours) under constant temperature and humidity conditions below 100°C to obtain a preliminarily dried disc sheet.

[0054] Wherein, the solvent (I) is a mixture or combination of water and a water-soluble high-boiling-point organic solvent, wherein the water-soluble high-boiling-point organic solvent has a boiling point higher than 120°C at 1 standard atmosphere; preferably, the water-soluble high-boiling-point organic solvent is butanediol, more preferably 1,3-butanediol or 1,4-butanediol.

[0055] In solvent (I), the mass ratio of the water-soluble high-boiling-point organic solvent to water is 0.005-1:1, preferably 0.0055-0.9:1, preferably 0.006-0.8:1, preferably 0.0065-0.7:1, preferably 0.007-0.6:1, preferably 0.0075-0.5:1, preferably 0.008-0.4:1, preferably 0.0085-0.3:1, preferably 0.009-0.2:1, preferably 0.0095-0.1:1, preferably 0.01-0.08:1, preferably 0.01-0.065:1, preferably 0.01-0.05:1;

[0056] 2) The preliminarily dried disc-shaped sheet (together with the mold) obtained in step 1) above is subjected to a second stage of drying at a temperature of 105-400℃ to obtain a ceramic disc spring blank;

[0057] 3) The ceramic disc spring blank is debonded, then sintered, and then demolded to obtain the debonded and sintered ceramic spring blank;

[0058] 4) The ceramic disc spring blank after debinding and sintering is pressure-impregnated with silicon halides to allow the silicon halides to penetrate into the ceramic disc spring blank after debinding and sintering. Then, it is placed in liquid ammonia or hydrated hydrazine hydrochloride for reaction, so that the silicon halides that have penetrated into the ceramic disc spring blank react to form iminosilicon precipitate. After the reaction is completed, the ceramic disc spring blank is placed in a molding mold and then placed in a sintering furnace for high-temperature heat treatment in an inert atmosphere (e.g., nitrogen atmosphere), for example, at a temperature of 800-1300℃ (preferably 900-1250℃, preferably 950-1230℃, preferably 1000-1200℃). Then, it is demolded to obtain the ceramic disc spring.

[0059] Preferably, in all the above-described preparation methods of this application, the first-stage drying treatment of the wet blank in step 1) is performed as follows:

[0060] The first stage of drying is carried out under constant temperature and humidity conditions of 40-90% humidity and 5-40°C, more preferably under constant temperature and humidity conditions of 45-88% humidity and 7-38°C, more preferably under constant temperature and humidity conditions of 50-86% humidity and 10-35°C, more preferably under constant temperature and humidity conditions of 53-85% humidity and 12-32°C, more preferably under constant temperature and humidity conditions of 55-83% humidity and 15-30°C, and even more preferably under constant temperature and humidity conditions of 57-82% humidity and 17-28°C.

[0061] More preferably, in all the above-described preparation methods of this application, the first-stage drying treatment of the wet blank in step 1) is performed as follows:

[0062] The prepared ceramic spring blank, along with the mold, is immersed in a mixture of glycerin and silicone oil in a mass ratio of (0.5-2):1 (preferably 0.7-1.5:1; such as 1:1) for 2-3 hours. Then, it is removed and placed in a cool place to allow excess moisturizing oil to drip off, thereby forming an oil film on the surface of the wet blank.

[0063] After an oil film forms on the surface of the ceramic wet blank, a small amount of water is released from the ceramic wet blank, and the ceramic spring wet blank undergoes simple surface hardening. A layer of highly elastic plastic film (such as polyethylene film) is attached to the ceramic surface to restrain the spring wet blank from structural deformation.

[0064] The ceramic spring, which is already bound by a high-elastic plastic film, along with the mold, is inserted into the rubber tube of a constant temperature and humidity fan for multi-stage drying of flowing gas with different temperatures and humidity levels.

[0065] First stage: Humidity 80%-90%, temperature 10-20℃, ventilate and dry for 8-12 hours until the green body hardens;

[0066] The second stage: with a humidity of 50%-70% and a temperature of 20-40℃, ventilate and dry for 5-6 hours, during which the green body shrinks significantly; during this process, the temperature can be appropriately reduced to slow down the shrinkage rate.

[0067] Third stage: Humidity 20%-40%, temperature 40-60℃, ventilate and dry for 2-3 hours. The spring blank is basically dry. Remove the high-elastic plastic film from the surface.

[0068] Fourth step: Place the spring blank in an oven and dry it in a well-ventilated environment at a temperature of 60-70℃ (for example, for more than 2 hours, such as 2-30 hours, 3-20 hours or 4-10 hours) until all the moisture inside the spring blank is dried.

[0069] Preferably, in the above-described method for preparing the helical ceramic spring of this application (i.e., in the first sub-scheme of the second aspect according to the present invention), step 3) is performed as follows:

[0070] 3) The (spiral) ceramic spring blank is debonded to obtain a spring green blank. Then, a support is placed in the inner cavity of the spring green blank. The spring green blank and a support with a thin layer of isolation powder on the surface are placed horizontally on the sintering powder. The sintering powder is then covered on top for pre-firing treatment. The support is then removed to obtain a hardened spring blank. A fixing piece with a thin layer of isolation powder on the surface is placed in the inner cavity of the hardened spring blank. The hardened spring blank and the fixing piece are then placed vertically in a crucible. A clamping piece is placed on the top of the hardened spring blank to press it against the top of the spring. The remaining gaps in the crucible are filled with sintering powder (ceramic powder: boron nitride 1:1). The hardened spring blank, the fixing piece, and the clamping piece are then sintered as a whole in a sintering furnace to obtain a debonded and sintered ceramic spring blank.

[0071] Generally, the insulating powder (boron nitride powder) is mixed with alcohol in a weight ratio of 1:(3-5) (e.g., 1:4) to form a slurry. This slurry is then applied to the surface of the support and the fastener, and dried in an oven to coat the surface of the support and the fastener with a thin layer of insulating powder.

[0072] In all the above preparation methods of this application, the silicon halide is preferably SiCl4 and / or SiBr4.

[0073] In all the above preparation methods of this application, preferably, the drying temperature in the second stage is 115-400℃, preferably 120-390℃, preferably 130-390℃, preferably 140-380℃, preferably 150-370℃, preferably 160-360℃, preferably 170-350℃, preferably 180-340℃, preferably 190-330℃, preferably 200-320℃.

[0074] In all the above preparation methods of this application, in step 3), the debinding process during the debinding sintering is carried out under a vacuum of 1×10⁻⁶. 1 -1×10 -1 The process is carried out under the condition of Pa, with a debinding temperature of 550-600℃ and a debinding time of 20-24 hours. After debinding, the process is carried out under a vacuum of 1×10⁻⁶ Pa. -1 -1×10

[0075] -3 Sintering is carried out under Pa conditions at a temperature of 1800-1900℃. The sintering time is generally 2-6 hours.

[0076] In all the above preparation methods of this application, in step 4), the surface treatment process is as follows: the ceramic spring blank after debinding and sintering is impregnated with silicon halide under pressure of 1-5 MPa, and then placed in liquid ammonia or hydrated hydrazine hydrochloride for reaction (e.g., 10-40 min); after the reaction is completed, the ceramic spring blank is heat-treated under nitrogen atmosphere at a temperature of 800-1300℃ (preferably 900-1250℃, preferably 950-1230℃, preferably 1000-1200℃) to obtain the ceramic spring (product or material).

[0077] Preferably, in the first sub-scheme of the second aspect of the present invention, the gelled ceramic wire comprising solvent (I) and ceramic powder (II) is prepared by a preparation method comprising the following steps:

[0078] (a) An organic monomer, crosslinking agent, and dispersant are added to solvent (I) to obtain a mixture. The pH of the mixture is adjusted to a value higher than 7.5 using an alkali (e.g., tetramethylammonium hydroxide or ammonia), such as pH 7.5-11, or pH 8, 8.5, 9, 9.5, 10, or 10.5. Then, composite or multiphase ceramic powder (II) is added and stirred to obtain a ceramic slurry; and

[0079] (b) After vacuum degassing the ceramic slurry, a catalyst (e.g., an amine catalyst) and an initiator are added and mixed. The resulting mixture is then injected into a molding tube and gelled (e.g., at 20-26°C) for 10-50 minutes. The gelled wire is then removed from the tube to obtain a gelled ceramic wire.

[0080] Preferably, the tubing is made of polypropylene, polytetrafluoroethylene, or polyethylene; preferably, the diameter of the tubing is 0.5-10 mm, more preferably 1-4 mm. The inventors experimented with numerous tubing materials and found that (gelled) ceramic wires formed from polypropylene (PP) tubing exhibit excellent surface smoothness and gloss. Therefore, in this application, polypropylene tubing is most preferably used to form the ceramic wire.

[0081] Preferably, in a second sub-scheme of the second aspect of the invention, the gelled ceramic sheet comprising solvent (I) and ceramic powder (II) is prepared by a preparation method comprising the following steps:

[0082] (a) An organic monomer, crosslinking agent, and dispersant are added to solvent (I) to obtain a mixture. The pH of the mixture is adjusted to a value higher than 7.5 using an alkali (e.g., tetramethylammonium hydroxide or ammonia), such as pH 7.5-11, or pH 8, 8.5, 9, 9.5, 10, or 10.5. Then, composite or multiphase ceramic powder (II) is added and stirred to obtain a ceramic slurry; and

[0083] (b) After vacuum degassing the ceramic slurry, a catalyst (e.g., an amine catalyst) and an initiator are added and mixed. The resulting mixture is then injected into a rectangular tube for molding and gelled (e.g., at 20-26°C) for 10-50 minutes. The gelled sheet is then removed from the tube to obtain a gelled ceramic sheet.

[0084] In a third sub-scheme of the second aspect of the present invention, preferably, the gelled concentric ceramic sheet comprising solvent (I) and ceramic powder (II) is prepared by a preparation method comprising the following steps:

[0085] (a) An organic monomer, crosslinking agent, and dispersant are added to solvent (I) to obtain a mixture. The pH of the mixture is adjusted to a value higher than 7.5 using an alkali (e.g., tetramethylammonium hydroxide or ammonia), such as pH 7.5-11, or pH 8, 8.5, 9, 9.5, 10, or 10.5. Then, composite or multiphase ceramic powder (II) is added and stirred to obtain a ceramic slurry; and

[0086] (b) After vacuum degassing the ceramic slurry, a catalyst (e.g., an amine catalyst) and an initiator are added and mixed. The resulting mixture is then poured into a tank with a smooth bottom and gelled (e.g., at 20-26°C) for 10-50 minutes to form a soft sheet of uniform thickness. While still wet, the sheet is cut to form concentric sheets, resulting in a gelled concentric ceramic sheet containing solvent (I) and ceramic powder (II).

[0087] Preferably, in the preparation method described above in this application, the organic monomer (i.e., the organic polymerizable monomer) is methacrylamide or hydroxymethylacrylamide. Preferably, the crosslinking agent is diallyl tartrate diamide or methylenebisacrylamide. Preferably, the dispersant is an aqueous solution of ammonium polyacrylate. The catalyst is tetramethylethylenediamine, and the initiator is hydrogen peroxide, an azo initiator (e.g., azobisisobutyronitrile), or an organic peroxide (e.g., benzoyl peroxide) or an inorganic persulfate (e.g., potassium persulfate) initiator.

[0088] Preferably, relative to 100 parts by weight of composite or multiphase ceramic powder (II), by weight:

[0089] The amount of organic monomer used is 0.5-6 parts, preferably 1-5 parts, and more preferably 1.5-4.5 parts;

[0090] The amount of crosslinking agent used is 0.01-0.2 parts, preferably 0.02-0.1 parts, and more preferably 0.04-0.09 parts;

[0091] The amount of dispersant used is 0.05-1.6 parts, preferably 0.07-1.5 parts, more preferably 0.1-1.3 parts, more preferably 0.2-1.2 parts, and more preferably 0.4-1 parts;

[0092] The amount of solvent (I) is 30-60 parts, preferably 32-55 parts, more preferably 35-50 parts, 37-48 parts, or 40-45 parts.

[0093] The amount of composite or multiphase ceramic powder (II) used is 100 parts by weight.

[0094] The amount of catalyst used is 0.1-2.5 parts, 0.3-2.3 parts, preferably 0.5-2 parts, more preferably 0.7-1.8 parts, more preferably 0.8-1.6 parts, more preferably 1-1.5 parts, for example 1.2, 1.3, 1.4 parts;

[0095] The amount of initiator is 0.1-7 parts, preferably 0.2-6.7 parts, preferably 0.3-6.5 parts, preferably 0.5-6.2 parts, preferably 0.7-6.1 parts, preferably 1-6 parts, more preferably 1.5-5.5 parts, preferably 2-5 parts, preferably 2.5-4.5 parts, preferably 3-4 parts.

[0096] Preferably, the composite or multiphase ceramic powder (II) is prepared by the following process: adding silicon nitride powder, boride powder and sintering aid to an organic solvent (e.g., anhydrous ethanol) and mixing, drying (e.g., drying at a temperature of 60-100°C) to obtain the composite or multiphase ceramic powder (II).

[0097] Preferably, in the preparation of composite or multiphase ceramic powder (II), the amounts or relative amounts of silicon nitride powder, boride powder, and sintering aid are:

[0098] (1) 100 parts by weight of silicon nitride,

[0099] (2) 4-28 parts by weight, preferably 5-25 parts by weight, more preferably 6-24 parts by weight, more preferably 7-23 parts by weight, more preferably 8-22 parts by weight, more preferably 9-21 parts by weight, more preferably 10-20 parts by weight, more preferably 11-19 parts by weight, more preferably 12-18 parts by weight, more preferably 13-17 parts by weight (e.g., 14, 15 or 16 parts by weight) of borides, wherein the borides are selected from one or two or more of zirconium boride, titanium boride, tantalum boride, and hafnium boride;

[0100] (3) 1-15 parts by weight, preferably 1.5-13 parts by weight, preferably 2-10 parts by weight, preferably 3-9 parts by weight, preferably 4-8 parts by weight, preferably 5-7 parts by weight (e.g. 5.5 or 6 or 6.5 parts by weight) of sintering aid containing lanthanides, wherein the sintering aid containing lanthanides is an oxide of lanthanides.

[0101] Preferably, the oxides of the lanthanides are selected from one or two or more (e.g., three, four, five or six) of lanthanum oxide, ytterbium oxide, erbium oxide, neodymium oxide, lutetium oxide and cerium oxide, such as lanthanum oxide + ytterbium oxide, lanthanum oxide + erbium oxide, ytterbium oxide + erbium oxide, lanthanum oxide + ytterbium oxide + erbium oxide.

[0102] Preferably, the boride is a mixture of any two boride powders selected from zirconium boride, titanium boride, tantalum boride, and hafnium boride in a weight ratio of 1-2:1.

[0103] Preferably, the weight ratio of the silicon nitride powder, boride powder and sintering aid is 100:(5-25):(2-10), more preferably 100:(10-20):(4-8), and more preferably 100:(12-18):(5-7).

[0104] Preferably, compared with using either zirconium boride powder or hafnium boride powder, using a mixture of zirconium boride powder and hafnium boride powder in a weight ratio of 1-2:1 (e.g., 1.5:1) can improve the surface smoothness and gloss of ceramic springs, increase the relative density, and improve high-temperature resistance.

[0105] When the content of boride in component (2) is less than 3 parts by weight, the disadvantage is that the spring still has a certain elasticity at room temperature, but as the temperature rises, the low-boron spring material cannot withstand the high-temperature oxidation environment in an oxygen environment, resulting in oxidation of the spring and a significant reduction in spring performance. When the content of component (2) is higher than 30 parts by weight, the disadvantage is that the material hardness and bending strength increase, while the fracture toughness decreases, resulting in an increase in the hardness and stiffness of the ceramic spring, but a decrease in the compression. This invention, by selecting an appropriate boride content, makes the resulting ceramic spring have good surface smoothness, as well as suitable stiffness, elasticity and high-temperature resistance.

[0106] When the content of sintering aid containing lanthanides in component (3) is less than 1 part by weight, the disadvantage is that during the sintering process, insufficient sintering aid cannot form a sufficient liquid phase, resulting in unstable phase transformation of silicon nitride material, uneven silicon nitride grain size after sintering, rough spring surface, and affected spring performance. When the content of component (3) is higher than 16 parts by weight, the disadvantage is that there is too much glass phase inside the spring. At high temperature, the glass phase reforms into a liquid phase, the spring softens, and creep occurs. This invention, by selecting appropriate sintering aid type and content, enables the obtained ceramic spring to have good surface smoothness and high strength properties.

[0107] For water-soluble high-boiling-point organic solvents (i.e., water-soluble organic solvents with a boiling point in the range of 120-350°C at 1 standard atmosphere), "water-soluble" means that the amount of the target organic solvent that can be dissolved in 100g of water at 25°C is more than 100g. "High-boiling-point" means that the boiling point of the target organic solvent (at 1 standard atmosphere) is higher than 120°C, that is, the boiling point of the organic solvent is (at least) 20°C higher than the boiling point of water (100°C), for example, the boiling point of the organic solvent is in the range of 120-350°C.

[0108] As a water-soluble, high-boiling-point organic solvent, known organic solvents can be used, and one can be used alone, or two or more can be used in combination. For example, as an organic solvent, any one selected from organic solvent A, organic solvent B, and organic solvent C described below can be used alone, or a mixture or combination of any two or more selected from organic solvent A, organic solvent B, and organic solvent C can be used.

[0109] Below, organic solvents with boiling points in the range of 120-200℃ (water-soluble high-boiling point) are referred to as (water-soluble high-boiling point) organic solvent A, organic solvents with boiling points in the range of 200℃ to 250℃ (above 200℃) are referred to as (water-soluble high-boiling point) organic solvent B, and organic solvents with boiling points in the range of 250℃ to 350℃ (above 250℃) are referred to as (water-soluble high-boiling point) organic solvent C.

[0110] Organic solvent A includes, for example, polyols such as ethylene glycol (boiling point: 198℃), propylene glycol (boiling point: 188℃), 1,2-butanediol (boiling point: 194℃), 2,3-butanediol (boiling point: 183℃), 2-methyl-1,3-propanediol (boiling point: 124℃), 2-methyl-2,4-pentanediol (boiling point: 198℃), 1,2,6-hexanetriol (boiling point: 178℃), 1,2,3-butanetriol (boiling point: 175℃), or 1,2,4-butanetriol (boiling point: 170℃); ethylene glycol monoethyl ether (boiling point: 135℃), and ethylene glycol-n-propyl ether (boiling point: 150℃). Polyol alkyl ethers such as ethylene glycol monobutyl ether (boiling point: 171℃), propylene glycol monoethyl ether (boiling point: 133℃), propylene glycol-n-butyl ether (boiling point: 171℃), propylene glycol-tert-butyl ether (boiling point: 153℃), tetraethylene glycol monomethyl ether (boiling point: 159℃), diethylene glycol methyl ether (boiling point: 194℃), diethylene glycol-n-butyl ether (boiling point: 171℃), or dipropylene glycol monomethyl ether (boiling point: 188℃); and nitrogen-containing organic compounds (organic amide compounds) such as ε-caprolactam (boiling point: 137℃), N-methylformamide (boiling point: 199℃), or N,N-dimethylformamide (boiling point: 153℃). Preferably, organic solvent A is a glycol compound, more preferably alkylene glycols (i.e., alkylene glycols) such as ethylene glycol, propylene glycol, 1,2-butanediol, and 2,3-butanediol, and even more preferably 1,2-butanediol and 2,3-butanediol. Organic solvent A can be used alone, or two or more can be used in combination.

[0111] As organic solvent B, it is, for example: diethylene glycol (boiling point: 244℃), dipropylene glycol (boiling point: 231℃), 1,3-propanediol (boiling point: 214℃), 1,3-butanediol (boiling point: 208℃), 1,4-butanediol (boiling point: 230℃), 1,2-pentanediol (boiling point: 206℃), 2,4-pentanediol (boiling point: 201℃), 2-methyl-1,3-butanediol (boiling point: 203℃), 3-methyl-1,3-butanediol (boiling point: 203℃), 1,5-pentanediol (boiling point: 242℃), 2,2-dimethyl-1,3-propanediol (boiling point: 208℃), 1,2-hexanediol (boiling point: 223℃), 1,6-hexanediol (boiling point: 250℃), 2,5-hex ...). Polyols such as 2-ethyl-1,3-hexanediol (boiling point: 217℃) or 2-ethyl-1,3-hexanediol (boiling point: 243℃); polyol alkyl ethers such as diethylene glycol monoethyl ether (boiling point: 202℃), diethylene glycol monobutyl ether (boiling point: 230℃), triethylene glycol methyl ether (boiling point: 249℃), dipropylene glycol-n-propyl ether (boiling point: 213℃), and tripropylene glycol methyl ether (boiling point: 243℃); polyol aromatic ethers such as ethylene glycol phenyl ether (boiling point: 237℃) or propylene glycol phenyl ether (boiling point: 243℃); and nitrogen-containing organic compounds (organopyrrolidone compounds) such as N-methyl-2-pyrrolidone (boiling point: 204℃), 2-pyrrolidone (boiling point: 245℃), 1,3-dimethylimidazolidineone (boiling point: 220℃) or N-methylpyrrolidone (boiling point: 202℃). Organic solvent B is preferably a glycol compound, more preferably an alkylene glycol (i.e., an alkylene glycol) such as diethylene glycol, dipropylene glycol, 1,3-butanediol (boiling point: 208°C), or 1,4-butanediol (boiling point: 230°C). Organic solvent B can be used alone, or two or more can be used in combination.

[0112] Organic solvent C is, for example, polyols such as triethylene glycol (boiling point: 287°C), tripropylene glycol (boiling point: 273°C), tetraethylene glycol (boiling point: 314°C), or glycerol (boiling point: 290°C); polyol alkyl ethers such as triethylene glycol ethyl ether (boiling point: 256°C), diethylene glycol-n-hexyl ether (boiling point: 259°C), or tripropylene glycol-n-propyl ether (boiling point: 261°C); and polyol aromatic ethers such as ethylene glycol monobenzyl ether (boiling point: 256°C). Organic solvent C is preferably a glycol compound, more preferably an alkylene glycol (i.e., alkylene glycol) such as triethylene glycol, tripropylene glycol, or tetraethylene glycol. Organic solvent C can be used alone, or two or more can be used in combination or in combination.

[0113] Polyvinyl alcohol (boiling point 175-190°C) can also be used as solvent (I), but it is not preferred.

[0114] The slurry prepared by this invention has a high solid content, good fluidity, and low viscosity, which is beneficial for injection molding into tubing and can impart high density to ceramic springs. During the drying process of water-based gel preforms, surface moisture evaporates first, and surface shrinkage causes blockage of surface pores, making it difficult for internal moisture to evaporate. The solvent (I) of this invention is water and a water-soluble high-boiling-point organic solvent (e.g., butanediol). An organic solvent (e.g., butanediol) that does not evaporate at the same time as water and is miscible with water is added to the water-based slurry. Its evaporation temperature is higher than that of water. After the surface moisture of the preform (the wire wound on the mold) evaporates, the organic solvent (e.g., butanediol) can adsorb the internal moisture to the preform surface for further removal. Finally, increasing the preform temperature removes all remaining moisture and organic solvent (e.g., butanediol), which facilitates the smooth progress of the drying process, shortens the drying cycle, and ensures complete solvent removal.

[0115] Preferably, the mass ratio (or weight ratio) of water and water-soluble high-boiling-point organic solvent (e.g., butanediol) in the solvent is 1:(0.01-0.05), and the butanediol is 1,3-butanediol or 1,4-butanediol.

[0116] According to a third aspect of the present invention, a ceramic spring (product or material) obtained by the above-described method for preparing a ceramic spring is provided.

[0117] In the ceramic springs (products or materials) according to the first and third embodiments of the present invention, the ceramic springs (products or materials) have outstanding performance:

[0118] According to GB / T 13841-92, the surface roughness of the above-mentioned ceramic springs is below 1.5 μm, preferably below 1.3 μm or below 1.0 μm, and more preferably below 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5 μm, 0.45 or 0.4 μm. The percentage of ceramic springs with surface micropore defects (i.e., the defect rate) is less than 0.1%.

[0119] According to GB / T 2595-2010, the relative density of the above-mentioned ceramic springs reaches 96% or higher, preferably higher than 96.1%, preferably higher than 96.2%, higher than 96.3%, higher than 96.4%, higher than 96.5%, higher than 96.6%, higher than 96.7%, higher than 96.8%, higher than 96.9%, higher than 97%, higher than 97.1%, higher than 97.2%, higher than 97.3%, higher than 97.4%, higher than 97.5%, higher than 97.6%, higher than 97.7%, higher than 97.8%, higher than 97.9%, higher than 98%, higher than 98.1%, higher than 98.2%, higher than 98.3%, higher than 98.4%, higher than 98.5%, higher than 98.6%, higher than 98.7%, higher than 98.8%, higher than 98.9%, and higher than 99%.

[0120] According to GB / T 1239.2-2009, the stiffness of the above-mentioned ceramic spring is 5-24 N / mm, preferably 7-22 N / mm, preferably 10-20 N / mm, preferably 12-19 N / mm, and preferably 15-18 N / mm.

[0121] After undergoing a thermal shock temperature difference test at 1000℃, the stiffness value of the above-mentioned ceramic spring decreases by less than 10%, preferably less than 8%, preferably less than 6%, and preferably less than 4%.

[0122] According to GB / T 6569-2006, the bending strength of the above-mentioned ceramic spring material is 480-780MPa, preferably 520-775MPa, preferably 560-770MPa, preferably 570-760MPa, preferably 580-750MPa, preferably 590-740MPa, for example 650, 700 or 720MPa.

[0123] According to GB / T 23806-2009, the fracture toughness of the above-mentioned ceramic spring material is 8-11 MPa·m. 1 / 2 Preferably 9-10 MPa·m 1 / 2 .

[0124] According to GB / T 16534-2009, the Vickers hardness of the above-mentioned ceramic spring material is 13-16 GPa, preferably 14-15 GPa.

[0125] According to GB / T 10700-2006, the elastic modulus of the above-mentioned ceramic spring material is 260-300 GPa, preferably 270-290 GPa.

[0126] According to GB / T 32329-2015, under the condition of oxidation at 1500℃ for 20 hours, the absolute value of the mass change rate of the ceramic spring is less than 1%. This indicates that the ceramic spring has excellent oxidation resistance.

[0127] According to a fourth aspect of the present invention, the ceramic spring (product or material) is provided for use in aerospace, new energy, defense and military products, chemical industry, and transportation. Currently, it is mainly used in equipment operating in high-temperature environments, such as engines and batteries.

[0128] In the aerospace field, when the space shuttle reaches a speed of Mach 5, its surface temperature can reach as high as 1280℉. Therefore, in order to prevent high temperature from being conducted from the surface of the spacecraft to the interior, the thermal sealing system is a necessary and critical structure, which is widely used in manned spacecraft, supersonic vehicles, space shuttles and reusable launch vehicles. The thermal sealing system is composed of complex mechanical components, including elastic elements. Its operating temperature is above 800℃. Metal materials still cannot meet the requirements of long-term use conditions. Therefore, ceramic springs are used to meet the requirements of its thermal sealing elastic elements.

[0129] In the new energy field, there are currently three main methods for fastening flat SOFC / SOEC: external pressurization, bolt fastening, and spring self-tightening. Under high-temperature operating conditions, SOFC / SOEC cells expand, increasing bolt pressure. Since bolt tightening cannot adjust the pressure, the screws experience tensile strain. After thermal cycling, the cells return to their normal temperature dimensions, reducing the pressure on the battery stack and impacting its performance, thus shortening battery life. External pressurization allows for adjustable pressure on the battery stack at high and low temperatures, extending the lifespan of SOFC / SOEC. However, servo presses and high-temperature steel supports are expensive, hindering widespread application. Spring self-tightening, by adding a self-tightening element above the bolt, enables the spring to autonomously regulate the internal pressure of the battery stack during thermal cycling, maintaining a long-term tight fit between individual cells, preventing cell breakage due to excessive expansion pressure, and extending battery life. Compared to external pressurization equipment, using ceramic springs as self-tightening elements in SOFCs effectively reduces the volume of the battery stack. Each battery stack requires a servo press and high-temperature steel support, which are expensive, while springs are relatively inexpensive. In the field of chemical equipment, ceramic springs can be used to manufacture pressure regulating valves for corrosive or high-temperature gases and liquids.

[0130] In a preferred embodiment of the present invention, the weight ratio of silicon nitride powder, boride powder, and sintering aid is 100:(5-25):(2-10); the boride powder is zirconium boride powder, hafnium boride powder, or a mixture of both, and the sintering aid is an oxide composed of lanthanides. The oxidation resistance of ceramic springs prepared using the multiphase ceramic powder of the present invention was tested according to GB / T 32329-2015. Under oxidation conditions of 1500℃ for 20 h, the addition of zirconium boride powder or hafnium boride powder to the silicon nitride powder reduced the weight gain rate of the ceramic springs prepared using only silicon nitride powder from 5.6% to less than 1%. The bending strength of the ceramic spring prepared using the multiphase ceramic powder of the present invention was tested according to GB / T 6569-2006. The bending strength increased from 400-500MPa of the ceramic spring prepared using only silicon nitride powder to 550-650MPa.

[0131] In a preferred embodiment of the present invention, the tubing is a polypropylene tubing, a polytetrafluoroethylene tubing, or a polyethylene tubing, and the diameter of the tubing is 1-4 mm. The preparation steps of the wire are as follows: the hose of a constant flow pump is connected to the opening of the tubing, the speed of the constant flow pump is adjusted to 50-200 r / min, the slurry containing the mixed catalyst and initiator is injected into the tubing, and after gel curing at a temperature of 20-26°C for 10-50 min, pressure is applied to the opening of the tubing to blow out the cured wire from the tubing, thus obtaining the wire. The present invention uses gel curing at a temperature of 20-26°C for 10-50 min to give the wire a certain degree of flexibility.

[0132] In a preferred embodiment of the present invention, the preparation process of the ceramic spring blank is as follows: using an automatic spring winding device, the winding speed is controlled at 5-20 r / min, and the wire is automatically wound onto the mold. It is dried for 2-10 hours under constant temperature and humidity conditions of 50-80% humidity and 20-26℃ to complete the first stage of drying treatment. Then, it is dried for 10-24 hours at a temperature of 200-300℃ to complete the second stage of drying treatment. After demolding, the ceramic spring blank is obtained.

[0133] The gel casting wire-automatic winding process improves the density of ceramic springs by increasing the solid content of the slurry, while vacuum degassing avoids defects such as porosity during molding. The slurry, containing a mixed catalyst and initiator, is injected into a tube, gel-formed into a wire, and then wound onto a mold. Wire formed directly from the tube ensures uniformity, and winding onto the mold guarantees structural integrity. The drying process is staged. The first stage removes some moisture under constant temperature and humidity conditions to prevent cracking caused by excessively rapid drying. The second stage uses butanediol to absorb internal moisture and further remove it from the surface. Finally, the temperature is increased to remove all remaining moisture and butanediol.

[0134] In a preferred embodiment of the present invention, the debinding process during the debinding sintering is carried out under a vacuum of 1×10⁻⁶. 1 -1×10 -1 The process is carried out under the following conditions: Pa; the debinding temperature is 550-600℃; the debinding time is 20-24 hours; after debinding, the process is carried out under a vacuum of 1×10⁻⁶ Pa. -1 -1×10 -3 Sintering is carried out under Pa conditions, with a sintering temperature of 1800-1900℃ and a sintering time of 2-6h.

[0135] In some embodiments of the present invention, after debinding and sintering, the ceramic spring blank after debinding and sintering is further subjected to surface treatment to obtain the high-performance ceramic spring; wherein, the surface treatment process is as follows: the ceramic spring blank after debinding and sintering is impregnated with silicon halide under pressure of 1-5 MPa, and then placed in liquid ammonia for 10-40 min. After the reaction is completed, the ceramic spring blank is heat-treated under nitrogen atmosphere at a temperature of 1000-1200°C to obtain the high-performance ceramic spring.

[0136] This invention uses silicon halides to impregnate the sintered ceramic spring blank with pressure, allowing the silicon halides to penetrate into the blank. Liquid ammonia is then added, causing the silicon halides to precipitate as iminosilicon. The blank is then heat-treated at 1000-1200°C under a nitrogen atmosphere. The iminosilicon thermally decomposes to form silicon nitride, which fills the original pores of the ceramic spring blank. Since the filler's components are identical to those of the blank, the chemical properties of the ceramic spring remain unchanged, while its physical and mechanical properties are improved. Porosity is reduced, density is further increased, surface smoothness is further improved, surface gloss is better, thermal shock resistance is better, and mechanical properties are also improved. According to GB / T2595-2010, ceramic springs with and without surface treatment were tested. The relative density of the surface-treated ceramic spring increased from 93% to over 96%. According to GB / T 13841-92, ceramic springs with and without surface treatment were tested. The surface roughness of the surface-treated ceramic spring decreased from 3.6μm to below 1.3μm. The stiffness of the surface-treated ceramic spring increased from 10-11 N / mm (for the untreated ceramic spring) to 12-13.5 N / mm. After a thermal shock test at 1000℃, the stiffness of the untreated ceramic spring decreased by 20%, while the stiffness of the surface-treated spring decreased by less than 10%.

[0137] Compared with the prior art, the present invention has the following beneficial effects:

[0138] 1. This invention improves the crystal phase structure of sintered ceramics by combining silicon nitride with a specific amount of zirconium boride and / or hafnium boride and a specific amount of lanthanide oxides as sintering aids. While the ceramic spring has excellent elasticity, rigidity, density and high temperature resistance, it also improves the surface smoothness and surface gloss of the ceramic spring.

[0139] 2. By using a mixture of water and water-soluble high-boiling-point organic solvents, and by using silicon halides for infiltration and modification, especially by using polypropylene (PP) tubing as a molding die for ceramic wires (for gelation), the surface smoothness and gloss of ceramic springs are further improved, and internal cracks and pores of ceramic springs are reduced to improve their strength and elasticity.

[0140] 3. The high-performance ceramic springs prepared by the method of this invention have high surface smoothness, good surface gloss, and a surface roughness below 1.3 μm; small dimensional errors and good batch stability; high density, with a relative density of over 96%; the stiffness of helical springs is 5-24 N / mm, for example 12-13.5 N / mm; the stiffness of leaf springs is 30-80 N / mm, for example 50-73.2 N / mm; and the stiffness of disc springs is 40-70 N / mm, for example 48-57.6 N / mm. After a thermal shock test at 1000℃, the stiffness decrease rate is less than 10%, preferably less than 8%, preferably less than 6%, and preferably less than 4%. Under oxidation conditions at 1500℃ for 20 hours, the weight gain rate of the ceramic springs is less than 1.0%, exhibiting excellent oxidation resistance; the bending strength is 480-780 MPa.

[0141] The fracture toughness of ceramic spring materials is 8-11 MPa·m 1 / 2 Preferably 9-10 MPa·m 1 / 2 .

[0142] The Vickers hardness of the ceramic spring material is 13-16 GPa, preferably 14-15 GPa.

[0143] The elastic modulus of the ceramic spring material is 260-300 GPa, preferably 270-290 GPa. Attached Figure Description

[0144] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be described below.

[0145] Figure 1 This is a photograph of the ceramic spring product of Embodiment 1 of the present invention.

[0146] Figure 2 This is a photograph of the ceramic wire obtained in Example 1 of the present invention.

[0147] Figure 3 These are photographs comparing the dimensions of ceramic springs of different sizes in Embodiments 1, 5, and 10 of the present invention.

[0148] Figure 4 This is a photograph of the small-batch production of ceramic springs in Embodiment 4 of the present invention.

[0149] Figure 5 This is a SEM image of the ceramic spring in Embodiment 4 of the present invention.

[0150] Figure 6 This is a photograph of the surface of the ceramic spring in Embodiment 4 of the present invention.

[0151] Figure 7This is a photograph of the ceramic leaf spring of Embodiment 11 of the present invention.

[0152] Figure 8 This is a schematic diagram of the assembly of the fastener and the spring hardening blank in Embodiment 5 of the present invention.

[0153] Figure 9 This is a schematic diagram showing the separation of the fixing member and the spring hardening blank in Embodiment 5 of the present invention.

[0154] The markings in the diagram are: 1-clamping component, 2-fixing component, 3-spring hardened blank.

[0155] Figure 10 This is a photograph of the ceramic spring according to Embodiment 5 of the present invention. Detailed Implementation

[0156] To make the objectives, technical solutions, and advantages of the present invention clearer, the various aspects of the present invention will be described in detail below with reference to specific embodiments.

[0157] In this embodiment, the tubing is made of polypropylene, polytetrafluoroethylene, or polyethylene, with a diameter of, for example, 1-4 mm. The preparation steps of the ceramic wire are as follows: The flexible hose of a constant flow pump is connected to the opening of the tubing. The speed of the constant flow pump is adjusted to 50-200 r / min. The ceramic slurry containing the mixed catalyst and initiator is injected into the tubing. After gelation and curing at 20-26°C for 10-50 min, pressure is applied to the opening of the tubing to blow out the cured wire, thus obtaining the ceramic wire. In this embodiment, preferably, a lubricant (silicone oil or zinc stearate) can be added inside the tubing before injecting the slurry containing the mixed catalyst and initiator. For example, the wire prepared in Example 1 below is as follows... Figure 2 As shown, the wire is uniform in all positions and has a high degree of surface smoothness.

[0158] In this embodiment, the preparation process of the ceramic spring blank is as follows: an automatic spring winding device is used to control the winding speed at 5-20 r / min, and the wire is automatically wound onto the mold. The blank is dried for 2-10 hours under constant temperature and humidity conditions of 50-80% humidity and 20-26℃ to complete the first stage of drying. Then, the blank is dried for 10-24 hours at a temperature of 200-300℃ to complete the second stage of drying. The blank is then demolded to obtain the ceramic spring blank.

[0159] In this embodiment, the debinding process during debinding sintering is carried out under a vacuum of 1×10⁻⁶. 1 -1×10 -1 The process is carried out under the following conditions: Pa; the debinding temperature is 550-600℃; the debinding time is 20-24 hours; after debinding, the process is carried out under a vacuum of 1×10⁻⁶ Pa. -1 -1×10 -3Sintering is carried out under Pa conditions, with a sintering temperature of 1800-1900℃ and a sintering time of 2-6h.

[0160] In this embodiment, preferably, after debinding and sintering, the ceramic spring blank after debinding and sintering is further subjected to surface treatment to obtain a high-performance ceramic spring; wherein, the surface treatment process is as follows: the ceramic spring blank after debinding and sintering is impregnated with silicon halide under pressure of 1-5 MPa, and then placed in liquid ammonia for 10-40 min. After the reaction is completed, the ceramic spring blank is heat-treated under nitrogen atmosphere at a temperature of 1000-1200℃ to obtain a high-performance ceramic spring. In this embodiment, the silicon halide is preferably SiCl4 or SiBr4. Taking SiCl4 as an example, SiCl4 is diffused into the ceramic spring blank after debinding and sintering. Then, liquid ammonia is added, and SiCl4 reacts with liquid ammonia: SiCl4 + 4NH3 = Si(NH2)4↓ + 4HCl. That is, the SiCl4 diffused into the ceramic spring blank generates imino silicon precipitate. During the heat treatment process, the imino silicon thermally decomposes to generate silicon nitride, which fills the original pores of the ceramic spring blank. After filling, the chemical properties of the ceramic spring remain unchanged, while the physical and mechanical properties are improved. The porosity is reduced, the density is further improved, the surface smoothness is further improved, the surface gloss is good, the thermal shock resistance is better, and the mechanical properties are good.

[0161] For example, the high-performance ceramic spring prepared in Example 1 below is as follows: Figure 1 As shown, the high-performance ceramic spring has a high surface smoothness and good surface gloss.

[0162] Generally, the high-performance ceramic springs prepared in the embodiments of this invention have high density, with a relative density of over 96%; surface roughness below 1.0 μm; small dimensional error; and good batch stability. The stiffness of the helical spring is 12-15 N / mm; the stiffness of the leaf spring is 60-65 N / mm; and the stiffness of the disc spring is 52-58 N / mm. After a thermal shock test at 1000℃, the stiffness value decreases by less than 10%; under oxidation conditions at 1500℃ for 20 hours, the weight gain of the ceramic spring is less than 3.3%, exhibiting excellent oxidation resistance; and the bending strength is 660-760 MPa.

[0163] Example 1

[0164] This embodiment provides a method for preparing a high-performance ceramic spring, including the following steps:

[0165] S1. Preparation of multiphase ceramic powder: Silicon nitride powder, hafnium boride powder and lanthanum oxide sintering aid are added to anhydrous ethanol at a weight ratio of 1:2 (solid to anhydrous ethanol). The mixture is placed in a homogenizer and mixed for 5 minutes at a speed of 1500 r / min. After uniform mixing, it is dried at 100°C to obtain multiphase ceramic powder (II). The weight ratio of silicon nitride powder, hafnium boride powder and lanthanum oxide sintering aid is 100:25:10.

[0166] S2. Add 5 parts by weight of an aqueous solution (concentration 10 wt%) of monomer methacrylamide, 0.1 parts by weight of crosslinking agent diallyl tartaric acid diamide, and 1 part by weight of dispersant ammonium polyacrylate to 50 parts by weight of solvent (I) and stir. Adjust the pH of the mixture to pH=10 using tetramethylammonium hydroxide as a pH adjuster. Then add 100 parts by weight of the multiphase ceramic powder (II) obtained in step S1 above and mix using a homogenizer to obtain a ceramic slurry with good flowability. The solvent (I) is water and 1,4-butanediol, and the mass ratio of water to 1,4-butanediol is 1:0.05.

[0167] S3. After vacuum degassing the ceramic slurry, add 2 parts by weight of the catalyst tetramethylethylenediamine and 6 parts by weight of the initiator hydrogen peroxide (concentration 10wt%), stir and mix. Then, using a constant flow pump, connect the hose of the constant flow pump to the opening of the polypropylene (PP) pipe, adjust the speed of the constant flow pump to 200 r / min, and inject the ceramic slurry mixed with the catalyst and initiator into the polypropylene (PP) pipe. After gel curing at 26℃ for 10 min to give it a certain degree of flexibility, apply pressure to the pipe opening and blow out the cured wire from the pipe to obtain the ceramic wire. The diameter of the polypropylene (PP) pipe is 2.2 mm. Before injecting the slurry mixed with the catalyst and initiator into the pipe, the inside of the pipe is moistened with silicone oil lubricant. A photograph of the ceramic wire is shown below. Figure 2 middle.

[0168] S4. Using an automatic spring winding device, the winding speed is controlled at 20r / min. The ceramic wire is automatically wound onto the molding die. It is dried for 10 hours under constant temperature and humidity conditions of 80% humidity and 20℃. After removing some of the moisture, the first stage of drying is completed. Then, it is placed in an oven and dried for 10 hours at 300℃ to complete the second stage of drying. The die is then removed to obtain the ceramic spring blank.

[0169] S5. Place the ceramic spring blank into a vacuum debinding furnace for debinding. During the debinding process, control the vacuum degree of the vacuum debinding furnace to 1×10⁻⁶. -1The debinding temperature was 550℃, and the debinding time was 20 hours. After debinding, the debinded ceramic spring blank was placed in a vacuum sintering furnace for sintering. During the sintering process, the vacuum degree of the vacuum sintering furnace was controlled at 1×10⁻⁶. -1 Pa, sintering temperature is 1800℃, sintering time is 6 hours.

[0170] S6. Surface treatment of the sintered ceramic spring blank after debinding to obtain a high-performance ceramic spring: The sintered ceramic spring blank after debinding is impregnated with silicon halide (SiBr4) under pressure of 5 MPa, allowing SiBr4 (silicon halide) to penetrate into the sintered ceramic spring blank. Then, it is placed in liquid ammonia for 10 minutes to react, causing the silicon halide infiltrated into the ceramic spring blank to form iminosilicon precipitate. After the reaction is complete, the ceramic spring blank is placed in a sintering furnace and heat-treated at 1200℃ under a nitrogen atmosphere to obtain a high-performance ceramic spring. A photograph of the ceramic spring is shown below. Figure 1 middle.

[0171] The high-performance ceramic spring prepared in Example 1 exhibits high density (98.4% relative density), high surface smoothness, good surface gloss, and a surface roughness of 0.5 μm; small dimensional error and good batch stability; a stiffness of 13.2 N / mm, with a stiffness decrease of less than 7% after a thermal shock test at 1000℃; a weight gain of only 0.83% after oxidation at 1500℃ for 20 hours, demonstrating excellent oxidation resistance; a bending strength of 697 MPa; and a fracture toughness of 8.91 MPa·m. 1 / 2 .

[0172] Example 2

[0173] Repeat Example 1, except that polytetrafluoroethylene (PTFE) tubing is used instead of polypropylene (PP) tubing.

[0174] The high-performance ceramic spring prepared in Example 2 has high density (98.1% relative density), high surface smoothness, good surface gloss, and a surface roughness of 0.9 μm; small dimensional error and good batch stability; a stiffness of 13.0 N / mm, with a stiffness decrease of less than 8% after a thermal shock test at 1000℃; a weight gain of only 0.95% after oxidation at 1500℃ for 20 hours, demonstrating excellent oxidation resistance; a bending strength of 692 MPa; and a fracture toughness of 8.8 MPa·m. 1 / 2 .

[0175] The results show that Example 1, which uses PP tubing, improves the surface smoothness and gloss of the ceramic spring compared to Example 2, which uses polytetrafluoroethylene tubing.

[0176] Example 3

[0177] Repeat Example 1, except that polyethylene pipes are used instead of polypropylene (PP) pipes.

[0178] The high-performance ceramic spring prepared in Example 3 has high density (98.0% relative density), high surface smoothness, good surface gloss, and a surface roughness of 0.8 μm; small dimensional error and good batch stability; a stiffness of 12.9 N / mm, with a stiffness decrease of less than 8% after a thermal shock test at 1000℃; a weight gain of only 0.87% after oxidation at 1500℃ for 20 hours, demonstrating excellent oxidation resistance; a bending strength of 680 MPa; and a fracture toughness of 8.95 MPa·m. 1 / 2

[0179] The results show that Example 1, which uses PP pipe, improves the surface smoothness and gloss of the ceramic spring compared to Example 3, which uses polyethylene pipe.

[0180] Example 4 (Preferred version of the invention)

[0181] Example 1 was repeated, except that the same amount of zirconium boride powder and hafnium boride powder (weight ratio 1.5:1) was used instead of hafnium boride powder. That is, the weight ratio of silicon nitride powder, zirconium boride powder and hafnium boride powder mixture and lanthanum oxide sintering aid was 100:25:10.

[0182] The high-performance ceramic spring prepared in Example 4 has high density (98.5% relative density), high surface smoothness, good surface gloss, and a surface roughness of 0.3 μm; small dimensional error and good batch stability; a stiffness of 14.2 N / mm, with a stiffness decrease of less than 6% after a thermal shock test at 1000℃; a weight gain of only 0.64% after oxidation at 1500℃ for 20 hours, demonstrating excellent oxidation resistance; a bending strength of 754 MPa; and a fracture toughness of 9.3 MPa·m. 1 / 2 Ablation performance: Under ablation conditions of 2000℃ and 350s, the mass ablation rate is -0.053mg / s, and the linear ablation rate is -0.377μm / s.

[0183] The results show that, compared with Examples 1-3 which used either zirconium boride powder or hafnium boride powder, Example 4, which used a mixture of zirconium boride powder and hafnium boride powder, can further improve the surface smoothness and gloss of the ceramic spring, increase the relative density, and improve the high-temperature resistance.

[0184] Comparative Example 1

[0185] Example 1 was repeated, except that in addition to using the same weight of lanthanum oxide as a sintering aid, a small amount of MgO was also used as a sintering aid. That is, the weight ratio of silicon nitride powder, hafnium boride powder, lanthanum oxide as a sintering aid, and MgO as a sintering aid was 100:25:10:3.

[0186] The high-performance ceramic spring prepared in Comparative Example 1 has a relative density of 97.8%; slightly poor surface smoothness and gloss, with a surface roughness of 2.8 μm; small dimensional error and good batch stability; a stiffness of 12.4 N / mm, with a stiffness decrease of less than 9% after a thermal shock test at 1000℃; a weight gain of 4.2% after oxidation at 1500℃ for 20 hours, indicating slightly poor oxidation resistance; a bending strength of 603 MPa; and a fracture toughness of 8.3 MPa·m. 1 / 2 .

[0187] The results show that when a small amount of MgO is present in the ceramic spring, it affects the crystal structure of the ceramic spring, resulting in a significant decrease in the surface smoothness (significantly increased roughness), as well as a decrease in its bending strength and elasticity.

[0188] Comparative Example 2

[0189] Example 1 was repeated, but with a larger amount of hafnium boride powder, wherein the weight ratio of silicon nitride powder, hafnium boride powder and sintering aid lanthanum oxide was 100:30:10.

[0190] The high-performance ceramic spring prepared in Comparative Example 2 has a relative density of 98.2%; slightly poor surface smoothness and gloss, with a surface roughness of 3.2 μm; small dimensional error and good batch stability; a stiffness of 10.7 N / mm, with a stiffness decrease of less than 8% after a thermal shock test at 1000℃; a weight gain of 1.4% after oxidation at 1500℃ for 20 hours; a bending strength of 587 MPa; and a fracture toughness of 8.0 MPa·m. 1 / 2

[0191] The results show that when more hafnium boride is used, although the stiffness of the ceramic spring is improved, the surface roughness of the ceramic spring increases, and its bending strength and elasticity decrease significantly.

[0192] Comparative Example 3

[0193] Example 1 was repeated, but with a smaller amount of hafnium boride powder, wherein the weight ratio of silicon nitride powder, hafnium boride powder and sintering aid lanthanum oxide was 100:3.5:10.

[0194] The high-performance ceramic spring prepared in Comparative Example 3 has a relative density of 97.5%; slightly poor surface smoothness and gloss, with a surface roughness of 2.3 μm; small dimensional error and good batch stability; a stiffness of 11.2 N / mm, with a stiffness decrease of more than 11% after a thermal shock test at 1000℃; a weight gain of 1.1% after oxidation at 1500℃ for 20 hours, indicating slightly poor oxidation resistance; a bending strength of 655 MPa; and a fracture toughness of 7.2 MPa·m. 1 / 2

[0195] The results show that using a smaller amount of hafnium boride leads to an increase in the surface roughness of the ceramic spring and a decrease in its high-temperature resistance.

[0196] Comparative Example 4

[0197] Repeat Example 1, except that 5 wt% of silicon carbide whiskers with a length of 5-10 μm are added to the original slurry formulation. The weight ratio of ceramic powder to whiskers is 95:5.

[0198] The high-performance ceramic spring prepared in Comparative Example 4 has a relative density of 96.5%; poor surface smoothness and slightly poor surface gloss, with a surface roughness of 6.7 μm; small dimensional error and good batch stability; a stiffness of 10.1 N / mm, which decreased by more than 10% after a thermal shock test at 1000℃; a weight gain of 0.85% after oxidation at 1500℃ for 20 hours; weakened bending strength, with a bending strength of 594 MPa; and a fracture toughness of 9.2 MPa·m. 1 / 2

[0199] The results show that adding a small amount of silicon carbide whiskers leads to an increase in the surface roughness of the ceramic spring, a decrease in bending strength, and a slight increase in fracture toughness.

[0200] Example 5

[0201] This embodiment provides a method for preparing a high-performance ceramic spring, including the following steps:

[0202] S1. Preparation of multiphase ceramic powder: Silicon nitride powder, zirconium boride powder and sintering aid ytterbium oxide are added to anhydrous ethanol at a weight ratio of 1:2 (solid to anhydrous ethanol). The mixture is placed in a homogenizer and mixed for 30 minutes at a speed of 1200 r / min. After uniform mixing, the mixture is dried at 60°C to obtain multiphase ceramic powder (II). The weight ratio of silicon nitride powder, zirconium boride powder and sintering aid ytterbium oxide is 100:5:2.

[0203] S2. Add 1 part by weight of the monomer methacrylamide, 0.02 parts by weight of the crosslinking agent diallyl tartaric acid diamide, and 0.1 parts by weight of the dispersant ammonium polyacrylate (concentration 10 wt%) to 35 parts by weight of solvent (I). Adjust the pH of the mixture to pH=8 using tetramethylammonium hydroxide as a pH adjuster. Then add 100 parts by weight of multiphase ceramic powder and mix using a homogenizer to obtain a ceramic slurry with good flowability. The solvent (I) is water and 1,3-butanediol. The mass ratio of water to 1,3-butanediol in the solvent is 1:0.01.

[0204] S3. After vacuum degassing the above ceramic slurry, add 0.5 parts by weight of the catalyst tetramethylethylenediamine and 1 part by weight of the initiator hydrogen peroxide (concentration 10%). After mixing, use a constant flow pump, connecting the hose of the constant flow pump to the opening of the polypropylene pipe, and adjust the speed of the constant flow pump to 50 r / min. Inject the slurry containing the catalyst and initiator into the polypropylene pipe. After gel curing at 20℃ for 50 min to give it a certain degree of flexibility, apply pressure to the pipe opening to blow out the cured wire from the pipe, obtaining the ceramic wire. The diameter of the polypropylene pipe is 3 mm. Before injecting the slurry containing the catalyst and initiator into the pipe, zinc stearate lubricant is added inside the pipe for lubrication.

[0205] S4. Using an automatic spring winding device, the winding speed is controlled at 5r / min. The ceramic wire is automatically wound onto the mold for forming. It is dried for 2 hours under constant temperature and humidity conditions of 50% humidity and 26℃. After removing some of the moisture, the first stage of drying is completed. Then, it is placed in an oven and dried at 200℃ for 24 hours to complete the second stage of drying. After demolding, the ceramic spring blank is obtained.

[0206] S5. Place the ceramic spring blank into a vacuum debinding furnace for debinding. During the debinding process, control the vacuum degree of the vacuum debinding furnace to 1×10⁻⁶. -1 The debinding temperature is 600℃, and the debinding time is 24 hours. After debinding, the separating powder (boron nitride powder) is mixed with alcohol at a weight ratio of 1:4 to form a slurry. This slurry is then applied to the surfaces of the support and fixing parts and dried in an oven to coat the surfaces of the support and fixing parts with a thin layer of separating powder. The support is then placed inside the cavity of the spring blank, and the spring blank and support are placed horizontally on the sintering powder. The top is then covered with sintering powder for pre-firing treatment. The pre-firing temperature is controlled at a vacuum degree of 1×10⁻⁶ in the vacuum sintering furnace. -1The sintering temperature was 1400℃, and the holding time was 30 min. The support was removed to obtain a spring-hardened blank. A fixing component was placed inside the spring-hardened blank, and then the spring-hardened blank and fixing component were placed vertically in a crucible. A clamping component was placed on the top of the spring-hardened blank, pressing it firmly against the top of the spring. The remaining gaps in the crucible were filled with sintering powder (ceramic powder: boron nitride 1:1). The spring-hardened blank, fixing component, and clamping component were then sintered as a whole in a sintering furnace. During sintering, the vacuum degree of the vacuum sintering furnace was controlled at 1×10⁻⁶. -1 Pa, sintering temperature is 1900℃, sintering time is 2 hours.

[0207] S6. Surface treatment of the sintered ceramic spring blank after debinding to obtain a high-performance ceramic spring: The sintered ceramic spring blank after debinding is impregnated with silicon halide (SiCl4) under pressure of 1 MPa to allow the silicon halide (SiCl4) to penetrate into the sintered ceramic spring blank. Then, it is placed in liquid ammonia for 40 minutes to react, so that the silicon halide penetrated into the ceramic spring blank can form iminosilicon precipitate. After the reaction is completed, the ceramic spring blank is placed in a sintering furnace and heat-treated at 1000℃ under a nitrogen atmosphere to obtain a high-performance ceramic spring.

[0208] The high-performance ceramic spring prepared in Example 5 exhibits high density (96.4% relative density), high surface smoothness, good surface gloss, and a surface roughness of 0.62 μm; small dimensional error and good batch stability; a stiffness of 12 N / mm, with a stiffness decrease of less than 10% after a 1000℃ thermal shock test; a weight gain of only 0.79% after 20 hours of oxidation at 1500℃, demonstrating excellent oxidation resistance; a bending strength of 686 MPa; and a fracture toughness of 8.7 MPa·m. 1 / 2

[0209] Example 6

[0210] Repeat Example 5, except that polytetrafluoroethylene (PTFE) tubing is used instead of polypropylene (PP) tubing.

[0211] The high-performance ceramic spring prepared in Example 6 has high density (96.3% relative density), high surface smoothness, good surface gloss, and a surface roughness of 0.84 μm; small dimensional error and good batch stability; a stiffness of 12.6 N / mm, with a stiffness decrease of less than 10% after a thermal shock test at 1000℃; a weight gain of only 0.82% after oxidation at 1500℃ for 20 hours, demonstrating excellent oxidation resistance; a bending strength of 680 MPa; and a fracture toughness of 8.7 MPa·m. 1 / 2 .

[0212] The results showed that, compared with the example using polytetrafluoroethylene (PTFE) tubing, Example 5, which used PP tubing, had no significant difference in spring performance, but the surface roughness was improved.

[0213] Example 7

[0214] Repeat Example 5, except that silicone oil lubricant is used instead of zinc stearate lubricant.

[0215] The high-performance ceramic spring prepared in Example 7 has high density (96.4% relative density), high surface smoothness, good surface gloss, and a surface roughness of 0.76 μm; small dimensional error and good batch stability; a stiffness of 12.3 N / mm, with a stiffness decrease of less than 8% after a thermal shock test at 1000℃; a weight gain of only 0.85% after oxidation at 1500℃ for 20 hours, demonstrating excellent oxidation resistance; a bending strength of 684 MPa; and a fracture toughness of 8.6 MPa·m. 1 / 2 .

[0216] The results show that Example 5, which uses zinc stearate lubricant, improves the surface smoothness and gloss of the ceramic spring compared to Example 7, which uses silicone oil lubricant.

[0217] Example 8

[0218] Example 5 was repeated, except that the same amount of a mixture of ytterbium oxide powder and erbium oxide powder (weight ratio 5:3) was used instead of ytterbium oxide powder. That is, the weight ratio of silicon nitride powder, zirconium boride powder, and the sintering aid ytterbium oxide powder and erbium oxide mixed powder was 100:5:2.

[0219] The high-performance ceramic spring prepared in Example 8 has high density (97.2%), slightly poor surface smoothness, good surface gloss, and a surface roughness of 0.71 μm; small dimensional error and good batch stability; a stiffness of 13.6 N / mm, with a stiffness decrease of less than 6% after a thermal shock test at 1000℃; a weight gain of only 0.62% after oxidation at 1500℃ for 20 hours, demonstrating excellent oxidation resistance; a bending strength of 700 MPa; and a fracture toughness of 8.1 MPa·m. 1 / 2 .

[0220] The results show that, compared with Examples 5-7 which used either ytterbium oxide or erbium oxide powder, the sintering aid ytterbium oxide powder and erbium oxide mixed powder in Examples 8 of this invention can further improve the relative density of ceramic springs, enhance bending strength, and improve high-temperature resistance.

[0221] Example 9

[0222] Repeat Example 8, except that silicone oil lubricant is used instead of zinc stearate lubricant.

[0223] The high-performance ceramic spring prepared in Example 3 has high density (97.2% relative density), high surface smoothness, good surface gloss, and a surface roughness of 0.82 μm; small dimensional error and good batch stability; a stiffness of 13.6 N / mm, with a stiffness decrease of less than 6% after a thermal shock test at 1000℃; a weight gain of only 0.63% after oxidation at 1500℃ for 20 hours, demonstrating excellent oxidation resistance; a bending strength of 703 MPa; and a fracture toughness of 8.2 MPa·m. 1 / 2 .

[0224] The results show that Example 8, which uses zinc stearate lubricant, improves the surface smoothness and gloss of the ceramic spring compared to Example 9, which uses silicone oil lubricant.

[0225] Comparative Example 5

[0226] Example 5 was repeated, except that in addition to using the same weight of ytterbium oxide as a sintering aid, a small amount of MgO was also used as a sintering aid. That is, the weight ratio of silicon nitride powder, hafnium boride powder, lanthanum oxide as a sintering aid, and MgO as a sintering aid was 100:5:2:2.

[0227] The high-performance ceramic spring prepared in Comparative Example 5 has a relative density of 97.8%; slightly poor surface smoothness and gloss, with a surface roughness of 2.2 μm; small dimensional error and good batch stability; a stiffness of 9.7 N / mm, with a stiffness decrease of less than 13% after a thermal shock test at 1000℃; a weight gain of 1.2% after oxidation at 1500℃ for 20 hours, indicating a decrease in oxidation resistance; a bending strength of 560 MPa; and a fracture toughness of 7.6 MPa·m. 1 / 2 .

[0228] The results show that when a small amount of MgO is present in the ceramic spring, it affects the crystal structure of the ceramic spring and generates a large amount of eutectic phase during sintering, which affects the high-temperature performance of the sample.

[0229] Comparative Example 6

[0230] Example 1 was repeated, but with a larger amount of ytterbium oxide powder, wherein the weight ratio of silicon nitride powder, hafnium boride powder and sintering aid ytterbium oxide was 100:5:10.

[0231] The high-performance ceramic spring prepared in Comparative Example 6 has a relative density of 98.2%; slightly poor surface smoothness and gloss, with a surface roughness of 1.8 μm; small dimensional error and good batch stability; a stiffness of 10.2 N / mm, with a stiffness decrease of less than 10% after a thermal shock test at 1000℃; a weight gain of 2.2% after oxidation at 1500℃ for 20 hours, indicating a deterioration in oxidation resistance; a bending strength of 587 MPa; and a fracture toughness of 7.8 MPa·m. 1 / 2 .

[0232] The results show that while using more ytterbium oxide improves the stiffness of ceramic springs, it also leads to a decrease in fracture toughness and high-temperature oxidation resistance.

[0233] Example 10

[0234] This embodiment provides a method for preparing a high-performance (spiral) ceramic spring, including the following steps:

[0235] S1. Preparation of multiphase ceramic powder: Silicon nitride powder, zirconium boride powder and erbium oxide sintering aid are added to anhydrous ethanol at a weight ratio of 1:3 (solid to anhydrous ethanol). The mixture is placed in a homogenizer and mixed for 20 minutes at a speed of 1000 r / min. After uniform mixing, it is dried at 80°C to obtain multiphase ceramic powder (II). The weight ratio of silicon nitride powder, zirconium boride powder and erbium oxide sintering aid is 100:15:7.

[0236] S2. Add 3 parts by weight of the monomer methacrylamide, 0.07 parts by weight of the crosslinking agent diallyl tartaric acid diamide, and 0.5 parts by weight of the dispersant ammonium polyacrylate (concentration 10wt%) to 42 parts by weight of solvent (I) and stir. Adjust the pH of the mixture to pH=9 using tetramethylammonium hydroxide as a pH adjuster. Add 100 parts by weight of the above multiphase ceramic powder (II) and mix using a homogenizer to obtain a ceramic slurry with good flowability. The solvent (I) is water and 1,3-butanediol, and the mass ratio of water to 1,3-butanediol is 1:0.03.

[0237] S3. After vacuum degassing the ceramic slurry, add 1 part by weight of the catalyst tetramethylethylenediamine and 3 parts by weight of the initiator hydrogen peroxide (concentration 10wt%), stir and mix. Then, using a constant flow pump, connect the hose of the constant flow pump to the opening of the polypropylene (PP) pipe, adjust the speed of the constant flow pump to 150 r / min, and inject the slurry containing the catalyst and initiator into the polypropylene (PP) pipe. After gel curing at 24℃ for 30 min to give it a certain degree of flexibility, apply pressure to the pipe opening and blow out the cured wire from the pipe to obtain the ceramic wire. The diameter of the polypropylene (PP) pipe is 4 mm. Before injecting the slurry containing the catalyst and initiator into the pipe, add zinc stearate as a lubricant inside the pipe for lubrication.

[0238] S4. Using an automatic spring winding device, the winding speed is controlled at 15 r / min. The ceramic wire is automatically wound onto the forming mold. The prepared ceramic spring blank, along with the mold, is immersed in a mixture of glycerin and silicone oil at a mass ratio of 0.8:1 for 3 hours. Then, it is removed and placed in a cool place to allow excess moisturizing oil to drip off, thus forming an oil film on the surface of the wet blank. After the oil film forms on the surface of the ceramic spring blank, the ceramic spring blank undergoes simple surface hardening. A layer of high-elastic plastic film (such as polyethylene film) is attached to the ceramic surface to bind the spring blank and prevent structural deformation. The ceramic spring, which has been bound by the high-elastic plastic film, is inserted into the rubber tube of a constant temperature and humidity fan for multi-stage drying with flowing gas at different temperatures and humidity levels.

[0239] First stage: Humidity 87%, temperature 18℃, ventilated drying for 8 hours, the green body hardens;

[0240] Second stage: Humidity 62%, temperature 30℃, ventilated drying for 6 hours, the green body shrinks significantly;

[0241] Third stage: Humidity 31%, temperature 53℃, ventilate and dry for 3 hours. The spring blank is basically dry. Remove the high-elastic plastic film from the surface.

[0242] Fourth step: Place the spring blank in an oven and dry it at 60℃ for 12 hours until all the moisture inside the spring blank is dried; demold to obtain the ceramic spring blank.

[0243] S5. Place the ceramic spring blank into a vacuum debinding furnace for debinding. During the debinding process, control the vacuum degree of the vacuum debinding furnace to 1×10⁻⁶. -1 The debinding temperature was 570℃, and the debinding time was 22 hours. After debinding, the debinded ceramic spring blank was placed in a vacuum sintering furnace for sintering. During the sintering process, the vacuum degree of the vacuum sintering furnace was controlled at 1×10⁻⁶. -1 Pa, sintering temperature is 1850℃, sintering time is 3 hours.

[0244] S6. Alumina ceramic fibers are twisted into continuous fiber threads in bundles of 1k, and then woven to form a fiber tube sleeve with a cross-sectional circumference of 10mm. This sleeve is then fitted into the helical coil of the debonded and sintered ceramic spring. The ceramic spring blank with the ceramic fiber sleeve is then surface-treated to obtain a high-performance ceramic spring. The debonded and sintered ceramic spring blank is impregnated with silicon halide (SiCl4) under pressure of 2MPa to allow the silicon halide (SiCl4) to penetrate into the debonded and sintered ceramic spring blank. Then, it is placed in liquid ammonia for 30 minutes to react, causing the silicon halide that has penetrated into the ceramic spring blank to form iminosilicon precipitate. The ceramic spring blank is then placed in a sintering furnace and heat-treated at 1100℃ under a nitrogen atmosphere to obtain a high-performance ceramic spring.

[0245] The high-performance ceramic spring prepared in Example 10 has high density (97.2% relative density), a surface roughness of 0.95 μm, small dimensional error, and good batch stability. Its stiffness is 13.2 N / mm, and after a thermal shock test at 1000℃, the stiffness decreases by less than 9%. Under oxidation conditions at 1500℃ for 20 hours, the weight gain of the ceramic spring is less than 0.63%, demonstrating excellent oxidation resistance. Its bending strength is 703 MPa, and its fracture toughness is 8.1 MPa·m. 1 / 2； The spring will not shatter and fly away after it breaks.

[0246] This embodiment 10 improves the drying effect of the green body, better prevents shrinkage, deformation and cracking of the ceramic green body, and achieves precise control of the ceramic shape and size.

[0247] Example 11

[0248] This embodiment provides a method for preparing a high-performance ceramic leaf spring, including the following steps:

[0249] S1. Preparation of multiphase ceramic powder: Silicon nitride powder, hafnium boride powder and lanthanum oxide sintering aid are added to anhydrous ethanol at a weight ratio of 1:2 (solid to anhydrous ethanol). The mixture is placed in a homogenizer and mixed for 5 minutes at a speed of 1500 r / min. After uniform mixing, it is dried at 100°C to obtain multiphase ceramic powder (II). The weight ratio of silicon nitride powder, hafnium boride powder and lanthanum oxide sintering aid is 100:15:10.

[0250] S2. Add 5 parts by weight of an aqueous solution (concentration 10 wt%) of monomer methacrylamide, 0.1 parts by weight of crosslinking agent diallyl tartaric acid diamide, and 1 part by weight of dispersant ammonium polyacrylate to 50 parts by weight of solvent (I) and stir. Adjust the pH of the mixture to pH=10 using tetramethylammonium hydroxide as a pH adjuster. Then add 100 parts by weight of the multiphase ceramic powder (II) obtained in step S1 above and mix using a homogenizer to obtain a ceramic slurry with good flowability. The solvent (I) is water and 1,4-butanediol, and the mass ratio of water to 1,4-butanediol is 1:0.05.

[0251] S3. After vacuum degassing the ceramic slurry, add 2 parts by weight of the catalyst tetramethylethylenediamine and 6 parts by weight of the initiator hydrogen peroxide (concentration 10wt%), stir and mix. Then, using a constant flow pump, connect the hose of the constant flow pump to the opening of the polypropylene (PP) rectangular pipe, adjust the speed of the constant flow pump to 200 r / min, and inject the ceramic slurry mixed with the catalyst and initiator into the polypropylene (PP) pipe. After gel curing at 26℃ for 10 min, it will have a certain degree of flexibility. Apply pressure to the pipe opening to blow out the cured sheet from the pipe, obtaining the ceramic sheet. The width of the polypropylene (PP) rectangular pipe is 50 mm and the height is 6 mm. Before injecting the slurry mixed with the catalyst and initiator into the pipe, add silicone oil lubricant inside the pipe.

[0252] S4. Place the ceramic sheet in a bending mold and dry it for 10 hours under constant temperature and humidity conditions of 80% and 20℃. After removing some of the moisture, the first stage of drying is completed. Then, place it in an oven and dry it for 10 hours at 300℃ to complete the second stage of drying. Demold the sheet to obtain the ceramic spring blank.

[0253] S5. Place the ceramic spring blank into a vacuum debinding furnace for debinding. During the debinding process, control the vacuum degree of the vacuum debinding furnace to 1×10⁻⁶. 1 The debinding temperature was 550℃, and the debinding time was 20 hours. After debinding, the debinded ceramic leaf spring blank was placed in a vacuum sintering furnace for sintering. During the sintering process, the vacuum degree of the vacuum sintering furnace was controlled at 1×10⁻⁶. -1 Pa, sintering temperature is 1800℃, sintering time is 6 hours.

[0254] S6. Surface treatment of the sintered ceramic leaf spring blank after debinding to obtain a high-performance ceramic leaf spring: The sintered ceramic leaf spring blank after debinding is impregnated with silicon halide (SiBr4) under pressure of 5 MPa, so that SiBr4 (silicon halide) penetrates into the sintered ceramic leaf spring blank. Then, it is placed in liquid ammonia for 10 minutes to react, so that the silicon halide penetrated into the ceramic leaf spring blank generates iminosilicon precipitate. After the reaction is completed, the ceramic leaf spring blank is placed in a sintering furnace and heat-treated at 1200℃ under a nitrogen atmosphere to obtain a high-performance ceramic leaf spring.

[0255] The high-performance ceramic leaf spring prepared in Example 11 has high density (98.4% relative density), high surface smoothness, good surface gloss, and a surface roughness of 0.5 μm; small dimensional error and good batch stability; a stiffness of 60.5 N / mm, and a stiffness decrease rate of less than 6.8% after a thermal shock test at 1000℃; a weight gain of only 0.78% after oxidation at 1500℃ for 20 hours, demonstrating excellent oxidation resistance; a bending strength of 694 MPa; and a fracture toughness of 8.3 MPa·m. 1 / 2 .

[0256] Example 12

[0257] Example 11 was repeated, except that a polytetrafluoroethylene pipe with a rectangular cross-section was used instead of a polypropylene (PP) pipe with a rectangular cross-section.

[0258] The high-performance ceramic leaf spring prepared in Example 2 has high density (98.2% relative density), high surface smoothness, good surface gloss, and a surface roughness of 0.75 μm; small dimensional error and good batch stability; a stiffness of 61.1 N / mm, with a stiffness decrease of less than 8% after a thermal shock test at 1000℃; a weight gain of only 0.81% after oxidation at 1500℃ for 20 hours, demonstrating excellent oxidation resistance; a bending strength of 690 MPa; and a fracture toughness of 8.2 MPa·m. 1 / 2 .

[0259] The results show that Example 11, which uses PP tubing, improves the surface smoothness and gloss of the ceramic leaf spring compared to Example 12, which uses polytetrafluoroethylene tubing.

[0260] Example 13

[0261] Example 11 was repeated, except that a polyethylene pipe with a rectangular cross-section was used instead of a polypropylene (PP) pipe with a rectangular cross-section.

[0262] The high-performance ceramic leaf spring prepared in Example 13 has high density (98.0% relative density), high surface smoothness, good surface gloss, and a surface roughness of 0.8 μm; small dimensional error and good batch stability; a stiffness of 60.3 N / mm, with a stiffness decrease of less than 8% after a thermal shock test at 1000℃; a weight gain of only 0.79% after oxidation at 1500℃ for 20 hours, demonstrating excellent oxidation resistance; a bending strength of 698 MPa; and a fracture toughness of 8.2 MPa·m. 1 / 2 .

[0263] The results show that Example 11, which uses PP pipe, improves the surface smoothness and gloss of the ceramic spring compared to Example 13, which uses polyethylene pipe.

[0264] Comparative Example 7

[0265] Example 11 was repeated, except that in addition to using the same weight of lanthanum oxide as a sintering aid, a small amount of MgO was also used as a sintering aid. That is, the weight ratio of silicon nitride powder, hafnium boride powder, lanthanum oxide as a sintering aid, and MgO as a sintering aid was 100:25:10:3.

[0266] The high-performance ceramic leaf spring prepared in Comparative Example 7 has a relative density of 97.8%; slightly poor surface smoothness and gloss, and a surface roughness of 1.7 μm; small dimensional error and good batch stability; a stiffness of 59.7 N / mm, with a stiffness decrease of less than 11% after a thermal shock test at 1000℃; a weight gain of 0.81% after oxidation at 1500℃ for 20 hours, indicating slightly poor oxidation resistance; a bending strength of 603 MPa; and a fracture toughness of 8.1 MPa·m. 1 / 2 .

[0267] The results show that when a small amount of MgO is present in the ceramic leaf spring, it affects the crystal structure of the ceramic spring, resulting in a significant decrease in the surface smoothness (significantly increased roughness) and a reduction in its bending strength and elasticity.

[0268] Comparative Example 8

[0269] Example 11 was repeated, but with a larger amount of hafnium boride powder, wherein the weight ratio of silicon nitride powder, hafnium boride powder and sintering aid lanthanum oxide was 100:30:10.

[0270] The high-performance ceramic leaf spring prepared in Comparative Example 8 has a relative density of 98.2%; slightly poor surface smoothness and gloss, with a surface roughness of 1.8 μm; small dimensional error and good batch stability; a stiffness of 59.4 N / mm, with a stiffness decrease of less than 8% after a thermal shock test at 1000℃; a weight gain of 0.96% after oxidation at 1500℃ for 20 hours, indicating slightly poor oxidation resistance; a flexural strength of 587 MPa; and a fracture toughness of 7.9 MPa·m. 1 / 2 .

[0271] The results show that when more hafnium boride is used, although the stiffness of the ceramic leaf spring is improved, the surface roughness of the ceramic spring increases, and its bending strength and elasticity decrease significantly.

[0272] The present invention has been described above with reference to specific embodiments. These specific embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make various modifications, changes, or substitutions without departing from the essence of the present invention. Therefore, various equivalent variations made according to the present invention still fall within the scope of the present invention.

[0273] Example 14

[0274] Repeat the slurry preparation steps S1-S2 in Example 11.

[0275] S3. After vacuum degassing the ceramic slurry, add 2 parts by weight of the catalyst tetramethylethylenediamine and 6 parts by weight of the initiator hydrogen peroxide (concentration 10wt%), stir and mix. Then, using a constant flow pump, connect the hose of the constant flow pump to the opening of the polypropylene (PP) rectangular pipe, adjust the speed of the constant flow pump to 200 r / min, and inject the ceramic slurry mixed with the catalyst and initiator into the polypropylene (PP) tank. After gel curing at 26℃ for 10 min, it will have a certain degree of flexibility, resulting in ceramic sheets. The polypropylene (PP) rectangular tank is 5 mm thick, 50 mm long, and 50 mm wide. Before injecting the slurry mixed with the catalyst and initiator into the tank, add silicone oil lubricant inside the pipe.

[0276] S4. Cut the ceramic sheet into a ring shape with an outer diameter of 25mm and an inner diameter of 10mm using a mold. Place it in a dish-shaped mold and dry it for 10 hours under constant temperature and humidity conditions of 80% and 20℃. After removing some of the moisture, the first stage of drying is completed. Then, place it in an oven and dry it for 10 hours at a temperature of 300℃ to complete the second stage of drying. Demold the mold to obtain the ceramic disc spring blank.

[0277] Sintering was performed according to the S5-S6 process of Example 11.

[0278] The high-performance ceramic disc spring prepared in Example 14 has high density (98.0% relative density), high surface smoothness, good surface gloss, and a surface roughness of 0.8 μm; small dimensional error and good batch stability; a stiffness of 54.2 N / mm, with a stiffness decrease rate of less than 8% after a thermal shock test at 1000℃; a weight gain of only 0.79% after oxidation at 1500℃ for 20 hours, demonstrating excellent oxidation resistance; a bending strength of 694 MPa; and a fracture toughness of 8.2 MPa·m. 1 / 2 .

Claims

1. A ceramic spring, comprising or (mainly) composed of the following components: (1) 100 parts by weight of silicon nitride, (2) 4-28 parts by weight, preferably 5-25 parts by weight, more preferably 6-24 parts by weight, more preferably 7-23 parts by weight, more preferably 8-22 parts by weight, more preferably 9-21 parts by weight, more preferably 10-20 parts by weight, more preferably 11-19 parts by weight, more preferably 12-18 parts by weight, more preferably 13-17 parts by weight (e.g., 14, 15 or 16 parts by weight) of a boride, wherein the boride is selected from one or more of zirconium boride, titanium boride, tantalum boride, and hafnium boride; and (3) 1-15 parts by weight, preferably 1.5-13 parts by weight, preferably 2-10 parts by weight, preferably 3-9 parts by weight, preferably 4-8 parts by weight, preferably 5-7 parts by weight (e.g. 5.5 or 6 or 6.5 parts by weight) of sintering aid containing lanthanides, wherein the sintering aid containing lanthanides is an oxide of lanthanides. The sum of the weights of the above components (1), (2) and (3) is 92-100 wt% of the total weight of the ceramic spring, preferably 93-99.9 wt%, preferably 93.5-99.8 wt%, more preferably 94-99.7 wt%, more preferably 94.2-99.6 wt%, more preferably 94.5-99.5 wt%, more preferably 94.7-99.4 wt%, more preferably 95-99.3 wt%, more preferably 95.2-99.2 wt%, more preferably 95.4-99.1 wt%, more preferably 95.5-99.0 wt%, for example 95.7, 96, 96.2, 96.5, 96.7, 97, 97.2, 97.5, 97.7, 98, 98.2, 98.5, 98.7, 99 wt%, based on the total weight of the ceramic spring; Preferably, the ceramic spring is a helical spring, a beveled spring, a cylindrical spring, a conical spring, a leaf spring, or a disc spring.

2. The ceramic spring according to claim 1, wherein the lanthanide oxide is selected from one or more of lanthanum oxide, ytterbium oxide, erbium oxide, neodymium oxide, lutetium oxide, and cerium oxide; and / or Borides are mixtures or combinations of any two of zirconium boride, titanium boride, tantalum boride, and hafnium boride in a weight ratio of 1-2:1 (e.g., 1.5:1).

3. The ceramic spring according to claim 1 or 2, wherein, According to GB / T 1384-1992, the surface roughness of the above-mentioned ceramic spring is below 1.5 μm, preferably below 1.3 μm or below 1.0 μm, and preferably below 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5 μm, 0.45 or 0.4 μm; and / or According to GB / T 2595-2010, the relative density of the above-mentioned ceramic springs reaches 96% or higher, preferably higher than 96.1%, preferably higher than 96.2%, higher than 96.3%, higher than 96.4%, higher than 96.5%, higher than 96.6%, higher than 96.7%, higher than 96.8%, higher than 96.9%, higher than 97%, higher than 97.1%, higher than 97.2%, higher than 97.3%, higher than 97.4%, higher than 97.5%, higher than 97.6%, higher than 97.7%, higher than 97.8%, higher than 97.9%, higher than 98%, higher than 98.1%, higher than 98.2%, higher than 98.3%, higher than 98.4%, higher than 98.5%, higher than 98.6%, higher than 98.7%, higher than 98.8%, higher than 98.9%, and higher than 99%; and / or According to GB / T 1239.2-2009, the stiffness of the above-mentioned ceramic spring is 5-24 N / mm, preferably 7-22 N / mm, preferably 10-20 N / mm, preferably 12-19 N / mm, preferably 15-18 N / mm; and / or After undergoing a thermal shock temperature difference test at 1000℃, the stiffness of the aforementioned ceramic spring decreases by less than 10%, preferably less than 8%, more preferably less than 6%, and more preferably less than 4%; and / or According to GB / T 6569-2006, the bending strength of the above-mentioned ceramic spring material is 480-780 MPa, preferably 520-775 MPa, preferably 560-770 MPa, preferably 570-760 MPa, preferably 580-750 MPa, preferably 590-740 MPa, for example 650, 700 or 720 MPa; and / or According to GB / T 23806-2009, the fracture toughness of the above-mentioned ceramic spring material is 8-11 MPa·m. 1 / 2 Preferably 9-10 MPa·m 1 / 2 ; and / or According to GB / T 16534-2009, the Vickers hardness of the above-mentioned ceramic spring material is 13-16 GPa, preferably 14-15 GPa; and / or According to GB / T 10700-2006, the elastic modulus of the above-mentioned ceramic spring material is 260-300 GPa, preferably 270-290 GPa; and / or According to GB / T 32329-2015, under the condition of oxidation at 1500℃ for 20 hours, the absolute value of the mass change rate of the ceramic spring is less than 1%.

4. A method for preparing a ceramic spring, wherein the ceramic spring is a helical spring, the method comprising the following steps: 1) A gelled ceramic wire containing solvent (I) and ceramic powder (II) is wound onto a mold for forming to obtain a ceramic spring wet blank. The wet blank is subjected to a first-stage drying treatment (e.g., 2-20 hours, such as 4-18 hours, 6-16 hours, or 8-14 hours) under constant temperature and humidity conditions below 100°C to obtain a preliminarily dried wound ceramic wire. Wherein, the solvent (I) is a mixture or combination of water and a water-soluble high-boiling-point organic solvent, wherein the water-soluble high-boiling-point organic solvent has a boiling point higher than 120°C at 1 standard atmosphere; preferably, the water-soluble high-boiling-point organic solvent is butanediol, more preferably 1,3-butanediol or 1,4-butanediol. In solvent (I), the mass ratio of the water-soluble high-boiling-point organic solvent to water is 0.005-1:1, preferably 0.0055-0.9:1, preferably 0.006-0.8:1, preferably 0.0065-0.7:1, preferably 0.007-0.6:1, preferably 0.0075-0.5:1, preferably 0.008-0.4:1, preferably 0.0085-0.3:1, preferably 0.009-0.2:1, preferably 0.0095-0.1:1, preferably 0.01-0.08:1, preferably 0.01-0.065:1, preferably 0.01-0.05:1; 2) The preliminarily dried wound ceramic wire obtained in step 1) above is subjected to a second stage of drying at a temperature of 105-400℃, and then demolded to obtain a ceramic spring blank; 3) The (spiral) ceramic spring blank was debonded and then sintered to obtain a debonded and sintered ceramic spring blank; 4) The sintered ceramic spring blank is pressure-impregnated with silicon halides to allow the silicon halides to penetrate into the sintered ceramic spring blank. Then, it is placed in liquid ammonia or hydrated hydrazine hydrochloride for reaction, so that the silicon halides that have penetrated into the ceramic spring blank react to form iminosilicon precipitate. After the reaction is completed, the ceramic spring blank is placed in a sintering furnace and subjected to high-temperature heat treatment in an inert atmosphere (e.g., nitrogen atmosphere), for example, at a temperature of 800-1300℃ (preferably 900-1250℃, preferably 950-1230℃, preferably 1000-1200℃) to obtain the ceramic spring.

5. A method for manufacturing a ceramic spring, wherein the ceramic spring is a ceramic leaf spring, the method comprising the following steps: 1) A gelled ceramic sheet containing solvent (I) and ceramic powder (II) is placed on a ceramic mold for forming a leaf spring to obtain a wet ceramic spring blank. The wet blank is subjected to a first-stage drying treatment (e.g., 2-20 hours, such as 4-18 hours, 6-16 hours, or 8-14 hours) under constant temperature and humidity conditions below 100°C to obtain a preliminarily dried curved ceramic sheet. Wherein, the solvent (I) is a mixture or combination of water and a water-soluble high-boiling-point organic solvent, wherein the water-soluble high-boiling-point organic solvent has a boiling point higher than 120°C at 1 standard atmosphere; preferably, the water-soluble high-boiling-point organic solvent is butanediol, more preferably 1,3-butanediol or 1,4-butanediol. In solvent (I), the mass ratio of the water-soluble high-boiling-point organic solvent to water is 0.005-1:1, preferably 0.0055-0.9:1, preferably 0.006-0.8:1, preferably 0.0065-0.7:1, preferably 0.007-0.6:1, preferably 0.0075-0.5:1, preferably 0.008-0.4:1, preferably 0.0085-0.3:1, preferably 0.009-0.2:1, preferably 0.0095-0.1:1, preferably 0.01-0.08:1, preferably 0.01-0.065:1, preferably 0.01-0.05:1; 2) The preliminarily dried curved sheet obtained in step 1) above is subjected to a second stage of drying at a temperature of 105-400℃ to obtain a ceramic leaf spring blank; 3) The ceramic leaf spring blank is debonded, then sintered, and then demolded to obtain the debonded and sintered ceramic spring blank; 4) The ceramic leaf spring blank after debinding and sintering is pressure-impregnated with silicon halides to allow the silicon halides to penetrate into the ceramic leaf spring blank after debinding and sintering. Then, it is placed in liquid ammonia or hydrated hydrazine hydrochloride for reaction, so that the silicon halides that have penetrated into the ceramic leaf spring blank react to form iminosilicon precipitate. After the reaction is completed, the ceramic leaf spring blank is placed in a molding mold and then placed in a sintering furnace for high-temperature heat treatment in an inert atmosphere (e.g., nitrogen atmosphere), for example, heat treatment at a temperature of 800-1300℃ (preferably 900-1250℃, preferably 950-1230℃, preferably 1000-1200℃). Then, it is demolded to obtain the ceramic leaf spring.

6. A method for manufacturing a ceramic spring, wherein the ceramic spring is a ceramic disc spring, the method comprising the following steps: 1) A gelled concentric ceramic sheet containing solvent (I) and ceramic powder (II) is placed in a disc spring mold to obtain a wet ceramic spring blank. The wet blank is subjected to a first-stage drying treatment (e.g., 2-20 hours, such as 4-18 hours, 6-16 hours, or 8-14 hours) under constant temperature and humidity conditions below 100°C to obtain a preliminarily dried disc sheet. Wherein, the solvent (I) is a mixture or combination of water and a water-soluble high-boiling-point organic solvent, wherein the water-soluble high-boiling-point organic solvent has a boiling point higher than 120°C at 1 standard atmosphere; preferably, the water-soluble high-boiling-point organic solvent is butanediol, more preferably 1,3-butanediol or 1,4-butanediol. In solvent (I), the mass ratio of the water-soluble high-boiling-point organic solvent to water is 0.005-1:1, preferably 0.0055-0.9:1, preferably 0.006-0.8:1, preferably 0.0065-0.7:1, preferably 0.007-0.6:1, preferably 0.0075-0.5:1, preferably 0.008-0.4:1, preferably 0.0085-0.3:1, preferably 0.009-0.2:1, preferably 0.0095-0.1:1, preferably 0.01-0.08:1, preferably 0.01-0.065:1, preferably 0.01-0.05:1; 2) The preliminarily dried disc-shaped sheet obtained in step 1) above, together with the mold, is subjected to a second stage of drying at a temperature of 105-400℃ to obtain a ceramic disc spring blank. 3) The ceramic disc spring blank is debonded, then sintered, and then demolded to obtain the debonded and sintered ceramic spring blank; 4) The ceramic disc spring blank after debinding and sintering is pressure-impregnated with silicon halides to allow the silicon halides to penetrate into the ceramic disc spring blank after debinding and sintering. Then, it is placed in liquid ammonia or hydrated hydrazine hydrochloride for reaction, so that the silicon halides that have penetrated into the ceramic disc spring blank react to form iminosilicon precipitate. After the reaction is completed, the ceramic disc spring blank is placed in a molding mold and then placed in a sintering furnace for high-temperature heat treatment in an inert atmosphere (e.g., nitrogen atmosphere), for example, at a temperature of 800-1300℃ (preferably 900-1250℃, preferably 950-1230℃, preferably 1000-1200℃). Then, it is demolded to obtain the ceramic disc spring.

7. The method according to any one of claims 4-6, wherein the first stage drying treatment of the wet blank is performed as follows: The first stage of drying is carried out under constant temperature and humidity conditions of 40-90% humidity and 5-40°C, more preferably under constant temperature and humidity conditions of 45-88% humidity and 7-38°C, more preferably under constant temperature and humidity conditions of 50-86% humidity and 10-35°C, more preferably under constant temperature and humidity conditions of 53-85% humidity and 12-32°C, more preferably under constant temperature and humidity conditions of 55-83% humidity and 15-30°C, and even more preferably under constant temperature and humidity conditions of 57-82% humidity and 17-28°C.

8. The method according to any one of claims 4-6, wherein the first stage drying treatment of the wet blank is performed as follows: The prepared ceramic spring blank, along with the mold, is immersed in a mixture of glycerin and silicone oil in a mass ratio of (0.5-2):1 (preferably 0.7-1.5:1; such as 1:1) for 2-3 hours. Then, it is removed and placed in a cool place to allow excess moisturizing oil to drip off, thereby forming an oil film on the surface of the wet blank. After an oil film forms on the surface of the ceramic wet blank, a small amount of water is released from the ceramic wet blank, and the ceramic spring wet blank undergoes simple surface hardening. A layer of highly elastic plastic film (such as polyethylene film) is attached to the ceramic surface to restrain the spring wet blank from structural deformation. The ceramic spring, which is already bound by a high-elastic plastic film, along with the mold, is inserted into the rubber tube of a constant temperature and humidity fan for multi-stage drying of flowing gas with different temperatures and humidity levels. First stage: Humidity 80%-90%, temperature 10-20℃, ventilate and dry for 8-12 hours until the green body hardens; Second stage: Humidity 50%-70%, temperature 20-40℃, ventilated drying for 5-6 hours, the green body shrinks significantly; Third stage: Humidity 20%-40%, temperature 40-60℃, ventilate and dry for 2-3 hours. The spring blank is basically dry. Remove the high-elastic plastic film from the surface. Fourth step: Place the spring blank in an oven and dry it in a well-ventilated environment at a temperature of 60-70℃ (for example, for more than 2 hours, such as 2-30 hours, 3-20 hours or 4-10 hours) until all the moisture inside the spring blank is dried.

9. The method according to claim 4, 7 or 8, wherein, Step 3) is performed as follows: 3) The (spiral) ceramic spring blank is debonded to obtain a spring green blank. Then, a support is placed in the inner cavity of the spring green blank. The spring green blank and a support with a thin layer of isolation powder on the surface are placed horizontally on the sintering powder. The sintering powder is then covered on top for pre-firing treatment. The support is then removed to obtain a hardened spring blank. A fixing piece with a thin layer of isolation powder on the surface is placed in the inner cavity of the hardened spring blank. The hardened spring blank and the fixing piece are then placed vertically in a crucible. A clamping piece is placed on the top of the hardened spring blank to press it against the top of the spring. The remaining gaps in the crucible are filled with sintering powder (ceramic powder: boron nitride 1:1). The hardened spring blank, the fixing piece, and the clamping piece are then sintered as a whole in a sintering furnace to obtain a debonded and sintered ceramic spring blank.

10. The method according to any one of claims 4-9, wherein, The silicon halides are SiCl4 and / or SiBr4; and / or The temperature for the second stage of drying is 115-400℃, preferably 120-390℃, preferably 130-390℃, preferably 140-380℃, preferably 150-370℃, preferably 160-360℃, preferably 170-350℃, preferably 180-340℃, preferably 190-330℃, preferably 200-320℃; and / or In step 3) above, the debinding process during the debinding sintering is carried out under a vacuum of 1×10⁻⁶. 1 -1×10 -1 The process is carried out under the condition of Pa, with a debinding temperature of 550-600℃ and a debinding time of 20-24 hours. After debinding, the process is carried out under a vacuum of 1×10⁻⁶ Pa. -1 -1×10 -3 Sintering is carried out under the conditions of Pa, with a sintering temperature of 1800-1900℃ and a sintering time of 2-6 hours; and / or In step 4) above, the surface treatment process is as follows: the ceramic spring blank after debinding and sintering is impregnated with silicon halide under pressure of 1-5 MPa, and then placed in liquid ammonia or hydrated hydrazine hydrochloride for reaction (e.g., 10-40 min); after the reaction is completed, the ceramic spring blank is heat-treated in a nitrogen atmosphere at a temperature of 800-1300℃ (preferably 900-1250℃, preferably 950-1230℃, preferably 1000-1200℃) to obtain the (high-performance) ceramic spring.

11. The method according to claim 4, wherein, The gelled ceramic wire comprising solvent (I) and ceramic powder (II) is prepared by a preparation method including the following steps: (a) An organic monomer, crosslinking agent, and dispersant are added to solvent (I) to obtain a mixture. The pH of the mixture is adjusted to a value higher than 7.5 using an alkali (e.g., tetramethylammonium hydroxide or ammonia), such as pH 7.5-11, or pH 8, 8.5, 9, 9.5, 10, or 10.

5. Then, composite or multiphase ceramic powder (II) is added and stirred to obtain a ceramic slurry; and (b) After vacuum degassing the ceramic slurry, a catalyst (e.g., an amine catalyst) and an initiator are added and mixed. The resulting mixture is then injected into a molding tube and gelled (e.g., at 20-26°C) for 10-50 minutes. The gelled wire is then removed from the tube to obtain a gelled ceramic wire.

12. The method according to claim 11, wherein, The pipe is a polypropylene pipe, a polytetrafluoroethylene pipe, or a polyethylene pipe; preferably, the diameter of the pipe is 0.5-10 mm, more preferably 1-4 mm.

13. The method according to claim 5, wherein, The gelled ceramic sheet comprising solvent (I) and ceramic powder (II) is prepared by a preparation method including the following steps: (a) An organic monomer, crosslinking agent, and dispersant are added to solvent (I) to obtain a mixture. The pH of the mixture is adjusted to a value higher than 7.5 using an alkali (e.g., tetramethylammonium hydroxide or ammonia), such as pH 7.5-11, or pH 8, 8.5, 9, 9.5, 10, or 10.

5. Then, composite or multiphase ceramic powder (II) is added and stirred to obtain a ceramic slurry; and (b) After vacuum degassing the ceramic slurry, a catalyst (e.g., an amine catalyst) and an initiator are added and mixed. The resulting mixture is then injected into a rectangular tube for molding and gelled (e.g., at 20-26°C) for 10-50 minutes. The gelled sheet is then removed from the tube to obtain a gelled ceramic sheet.

14. The method according to claim 6, wherein, The gelled concentric ceramic sheet comprising solvent (I) and ceramic powder (II) is prepared by a method comprising the following steps: (a) An organic monomer, crosslinking agent, and dispersant are added to solvent (I) to obtain a mixture. The pH of the mixture is adjusted to a value higher than 7.5 using an alkali (e.g., tetramethylammonium hydroxide or ammonia), such as pH 7.5-11, or pH 8, 8.5, 9, 9.5, 10, or 10.

5. Then, composite or multiphase ceramic powder (II) is added and stirred to obtain a ceramic slurry; and (b) After vacuum degassing the ceramic slurry, a catalyst (e.g., an amine catalyst) and an initiator are added and mixed. The resulting mixture is then poured into a tank with a smooth bottom and gelled (e.g., at 20-26°C) for 10-50 minutes to form a soft sheet of uniform thickness. While still wet, the sheet is cut to form concentric sheets, resulting in a gelled concentric ceramic sheet containing solvent (I) and ceramic powder (II).

15. The method according to any one of claims 11-14, wherein, The organic monomer is methacrylamide or hydroxymethylacrylamide; and / or The crosslinking agent is diallyl tartaric acid diamide or methylenebisacrylamide; and / or The dispersant is an aqueous solution of ammonium polyacrylate; and / or The catalyst is tetramethylethylenediamine; and / or The initiator is hydrogen peroxide, an azo initiator (e.g., azobisisobutyronitrile), or an organic peroxide (e.g., benzoyl peroxide) or an inorganic persulfate (e.g., potassium persulfate) initiator.

16. The method according to any one of claims 11-14, wherein, Relative to 100 parts by weight of composite or multiphase ceramic powder (II), by weight: The amount of organic monomer used is 0.5-6 parts, preferably 1-5 parts, and more preferably 1.5-4.5 parts; The amount of crosslinking agent used is 0.01-0.2 parts, preferably 0.02-0.1 parts, and more preferably 0.04-0.09 parts; The amount of dispersant used is 0.05-1.6 parts, preferably 0.07-1.5 parts, more preferably 0.1-1.3 parts, more preferably 0.2-1.2 parts, and more preferably 0.4-1 parts; The amount of solvent (I) is 30-60 parts, preferably 32-55 parts, more preferably 35-50 parts, 37-48 parts, or 40-45 parts; The amount of composite or multiphase ceramic powder (II) used is 100 parts by weight; The amount of catalyst used is 0.1-2.5 parts, 0.3-2.3 parts, preferably 0.5-2 parts, more preferably 0.7-1.8 parts, more preferably 0.8-1.6 parts, more preferably 1-1.5 parts, for example 1.2, 1.3, 1.4 parts; The amount of initiator is 0.1-7 parts, preferably 0.2-6.7 parts, preferably 0.3-6.5 parts, preferably 0.5-6.2 parts, preferably 0.7-6.1 parts, preferably 1-6 parts, more preferably 1.5-5.5 parts, preferably 2-5 parts, preferably 2.5-4.5 parts, preferably 3-4 parts.

17. The method according to any one of claims 11-16, wherein, The composite or multiphase ceramic powder (II) is prepared by the following process: adding silicon nitride powder, boride powder and sintering aid into an organic solvent (e.g., anhydrous ethanol) and mixing, drying (e.g., drying at a temperature of 60-100°C) to obtain the composite or multiphase ceramic powder (II). Preferably, in the preparation of composite or multiphase ceramic powder (II), the amounts or relative amounts of silicon nitride powder, boride powder, and sintering aid are: (1) 100 parts by weight of silicon nitride, (2) 4-28 parts by weight, preferably 5-25 parts by weight, more preferably 6-24 parts by weight, more preferably 7-23 parts by weight, more preferably 8-22 parts by weight, more preferably 9-21 parts by weight, more preferably 10-20 parts by weight, more preferably 11-19 parts by weight, more preferably 12-18 parts by weight, more preferably 13-17 parts by weight (e.g., 14, 15 or 16 parts by weight) of borides, wherein the borides are selected from one or two or more of zirconium boride, titanium boride, tantalum boride, and hafnium boride; (3) 1-15 parts by weight, preferably 1.5-13 parts by weight, preferably 2-10 parts by weight, preferably 3-9 parts by weight, preferably 4-8 parts by weight, preferably 5-7 parts by weight (e.g. 5.5 or 6 or 6.5 parts by weight) of sintering aid containing lanthanides, wherein the sintering aid containing lanthanides is an oxide of lanthanides. Preferably, the oxides of the lanthanides are selected from one or two or more (e.g., three, four, five or six) of lanthanum oxide, ytterbium oxide, erbium oxide, neodymium oxide, lutetium oxide and cerium oxide, such as lanthanum oxide + ytterbium oxide, lanthanum oxide + erbium oxide, ytterbium oxide + erbium oxide, lanthanum oxide + ytterbium oxide + erbium oxide; Preferably, the boride is a mixture of any two boride powders selected from zirconium boride, titanium boride, tantalum boride, and hafnium boride in a weight ratio of 1-2:1; Preferably, the weight ratio of the silicon nitride powder, boride powder and sintering aid is 100:(5-25):(2-10), more preferably 100:(10-20):(4-8), and more preferably 100:(12-18):(5-7).

18. The method according to any one of claims 11-17, wherein, The water-soluble high-boiling-point organic solvent is selected from any one of organic solvent A, organic solvent B, and organic solvent C described below, or a mixture of any two or more of organic solvent A, organic solvent B, and organic solvent C: Organic solvent A: ethylene glycol, propylene glycol, 1,2-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 1,2,6-hexanetriol, 1,2,3-butanetriol or 1,2,4-butanetriol; ethylene glycol monoethyl ether, ethylene glycol-n-propyl ether, ethylene glycol monobutyl ether, propylene glycol monoethyl ether, propylene glycol-n-butyl ether, propylene glycol-tert-butyl ether, tetraethylene glycol monomethyl ether, diethylene glycol methyl ether, diethylene glycol-n-butyl ether or dipropylene glycol monomethyl ether; and ε-caprolactam, N-methylformamide or N,N-dimethylformamide; Organic solvent B: diethylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 2,4-pentanediol, 2-methyl-1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 1,2-hexanediol, 1,6-hexanediol, 2,5-hexanediol or 2-ethyl-1,3-hexanediol; diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol methyl ether, dipropylene glycol-n-propyl ether, tripropylene glycol methyl ether; ethylene glycol phenyl ether or propylene glycol phenyl ether; and N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolone or N-methylpyrrolidone; Organic solvent C: triethylene glycol, tripropylene glycol, tetraethylene glycol or glycerol; triethylene glycol ethyl ether, diethylene glycol-n-hexyl ether or tripropylene glycol-n-propyl ether; and ethylene glycol monobenzyl ether; Preferably, the mass ratio of water and water-soluble high-boiling-point organic solvents 1,3-butanediol and / or 1,4-butanediol in the solvent (I) is 1:(0.01-0.05).

19. A ceramic spring product or material obtained by the method according to any one of claims 4-18, wherein... According to GB / T 13841-92, the surface roughness of the ceramic spring product is below 1.5 μm, preferably below 1.3 μm or below 1.0 μm, and preferably below 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5 μm, 0.45 or 0.4 μm; and / or According to GB / T 2595-2010, the relative density of the ceramic spring product reaches 96% or higher, preferably higher than 96.1%, preferably higher than 96.2%, higher than 96.3%, higher than 96.4%, higher than 96.5%, higher than 96.6%, higher than 96.7%, higher than 96.8%, higher than 96.9%, higher than 97%, higher than 97.1%, higher than 97.2%, higher than 97.3%, higher than 97.4%, higher than 97.5%, higher than 97.6%, higher than 97.7%, higher than 97.8%, higher than 97.9%, higher than 98%, higher than 98.1%, higher than 98.2%, higher than 98.3%, higher than 98.4%, higher than 98.5%, higher than 98.6%, higher than 98.7%, higher than 98.8%, higher than 98.9%, and higher than 99%; and / or According to GB / T 1239.2-2009, the stiffness of the above-mentioned ceramic spring is 5-24 N / mm, preferably 7-22 N / mm, preferably 10-20 N / mm, preferably 12-19 N / mm, preferably 15-18 N / mm; and / or After undergoing a thermal shock temperature difference test at 1000℃, the stiffness of the aforementioned ceramic spring decreases by less than 10%, preferably less than 8%, more preferably less than 6%, and more preferably less than 4%; and / or According to GB / T 6569-2006, the bending strength of the above-mentioned ceramic spring material is 480-780 MPa, preferably 520-775 MPa, preferably 560-770 MPa, preferably 570-760 MPa, preferably 580-750 MPa, preferably 590-740 MPa, for example 650, 700 or 720 MPa; and / or According to GB / T 23806-2009, the fracture toughness of the above-mentioned ceramic spring material is 8-11 MPa·m. 1 / 2 Preferably 9-10 MPa·m 1 / 2 ; and / or According to GB / T 16534-2009, the Vickers hardness of the above-mentioned ceramic spring material is 13-16 GPa, preferably 14-15 GPa; and / or According to GB / T 10700-2006, the elastic modulus of the above-mentioned ceramic spring material is 260-300 GPa, preferably 270-290 GPa; and / or According to GB / T 32329-2015, under the condition of oxidation at 1500℃ for 20 hours, the absolute value of the mass change rate of the ceramic spring is less than 1%.

20. Use of the ceramic spring according to any one of claims 1-3 or the ceramic spring obtained by the method according to any one of claims 4-18, wherein the ceramic spring is used in the aerospace field, the new energy field, the defense industry, the chemical industry, and the transportation field.

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