Anti-fatigue bionic ceramic composite material as well as preparation method and application thereof

Abstract

The invention relates to the field of biomedical materials and mechanical engineering materials, in particular to an anti-fatigue bionic ceramic composite material and a preparation method and application thereof. According to the preparation method provided by the invention, a uniformly-distributed single-orientation microporous structure is formed in the brittle ceramic material, and a second phase with high toughness and even low modulus and high toughness is introduced, so that the ceramic composite material with the second phase in coaxial orientation distribution is rapidly constructed, and the second phase is used as a damage isolation micro-area; the composite material is endowed with graded crack propagation hindering capability, and fatigue crack propagation is effectively inhibited. And meanwhile, the overall energy is quickly dissipated under the periodic dynamic load, and fatigue crack initiation is slowed down. On the submicron scale, the second phase effectively induces fatigue crack deflection and bridging and isolates micro cracks. The debonding of the second phase and the ceramic skeleton interface on the nanoscale also dissipates the energy of crack tip expansion. The ceramic composite material disclosed by the invention has the characteristics of axial compression resistance and radial isotropy, and the fatigue limit ratio of ten million cycles is 70-90%.

Description

Technical Field

[0001] This invention relates to the fields of biomedical materials and mechanical engineering materials, specifically to a fatigue-resistant biomimetic ceramic composite material, its preparation method, and its application. Background Technology

[0002] Ceramic materials, with their superior properties such as high strength, high temperature resistance, and wear resistance, have become key materials in high-end fields such as aerospace, energy, medical, and precision machinery. However, due to their inherent structural brittleness and lack of mechanisms to inhibit fatigue crack propagation, ceramic materials are prone to fatigue crack initiation and rapid damage accumulation under cyclic dynamic loads, ultimately leading to catastrophic fracture failure, posing a significant threat to the safety of engineering structures and human life. Therefore, in-depth research on fatigue-resistant structural design techniques for ceramic materials has become an urgent need in the engineering field.

[0003] Many natural materials exhibit fascinating multi-scale structural features and possess excellent impact resistance and crack propagation resistance, providing inspiration for fatigue-resistant structural design of brittle materials. The unique hierarchical multi-scale structure of the hinge tissue of the bivalve *Cristariaplicata* endows it with high fatigue resistance and deformability. Its core structure is a folded fan-shaped region composed of radially arranged rigid aragonite nanowires and an elastic organic matrix. This combination of hard and soft elements effectively disperses stress and transforms external radial loads into circumferential deformation, inhibiting stress concentration and hindering the propagation and accumulation of fatigue damage (Deformable hard tissue with high fatigue resistance in the hinge of bivalve *Cristariaplicata*. Science. 2023. 380, 1252-1257). The horn of the bighorn sheep (Oviscanadensis) has an oriented tubular structure and a weak interface composed of layered keratin. At the microscopic level, energy can be absorbed through the collapse of the tubular structure, the weak interface can induce crack deflection and hinder crack propagation through interfacial friction, and the nanofibers dissipate energy through dynamic breakage and recombination of hydrogen bonds. The synergy of the multi-scale structure endows it with excellent impact resistance and fatigue resistance through a hierarchical crack propagation inhibition mechanism (Hierarchical structure and compressive deformation mechanisms of bighorn sheep (Oviscanadensis) horn. Acta Bio. 2017, 64, 1-14). Human cortical bone is composed of bone units centered on oriented Huff tubes and bonding lines. The bonding lines, characterized by low modulus and weak interfaces, can deflect and distort cracks by dispersing the stress field at the crack tip. Microcracks are isolated by the bonding lines, enhancing the bone's resistance to repetitive loads and preventing brittle fracture due to microcrack accumulation (Structure and mechanics of interfaces inbiological materials. Nat Rev Mater. 2016, 1, 16007). Typically, fatigue failure in ceramic materials involves two main stages: fatigue crack initiation and rapid subcritical crack propagation. Fatigue crack initiation is related to unavoidable stress concentration from fabrication defects, while subcritical crack propagation is related to the lack of internal mechanisms to hinder crack propagation within the ceramic. In recent years, significant progress has been made in structural design research aimed at strengthening and toughening ceramic materials. However, existing research largely focuses on improving the quasi-static mechanical properties of materials, neglecting the risk of fatigue failure caused by dynamic loads in engineering applications. How to introduce a hierarchical mechanism to inhibit fatigue crack propagation in brittle ceramics through directional structural design and achieve rapid preparation of fatigue-resistant composite ceramic materials remains a key challenge.

[0004] Currently, there are few patents related to the design of fatigue-resistant structures for ceramic materials. Patent CN119710383A discloses a fatigue-resistant aluminum alloy ceramic composite rod with good fatigue resistance (low cycle). Patent CN119870392A discloses a method for preparing a high-modulus, high-strength, and high-fatigue-resistant aluminum-based composite plate, with the fatigue limit ratio of the prepared in-situ self-generated ceramic particles reinforced aluminum-based composite material being approximately 50%. Patent CN111041288B discloses a method for preparing a high-strength, high-toughness, and fatigue-resistant in-situ aluminum-based composite material, using nano-ZrB2 ceramic particles as a reinforcing phase to improve the fatigue resistance of aluminum alloys, with a fatigue limit ratio of approximately 30%. However, most of the above patents use ceramic skeletons or ceramic particles as reinforcing phases to improve the fatigue resistance of metallic materials, but these methods suffer from complex preparation processes and limited improvement in fatigue limit. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a fatigue-resistant biomimetic ceramic composite material, its preparation method and application. The biomimetic ceramic composite material obtained by the preparation method provided by the present invention can effectively suppress fatigue crack propagation, and the fatigue limit ratio (the ratio of fatigue limit to static load limit) reaches 70%~90%.

[0006] This invention provides a method for preparing fatigue-resistant biomimetic ceramic composite materials, comprising the following steps:

[0007] S1) The ceramic slurry is subjected to unidirectional freezing and freeze-drying in sequence to obtain a unidirectional porous ceramic green body;

[0008] S2) The unidirectional porous ceramic green body obtained in step S1) is subjected to bi-radial densification or isostatic pressing densification to obtain a densified green body.

[0009] The bi-radial densification specifically includes: taking the pore direction of the unidirectional porous ceramic green body as the z-axis, and taking the two mutually perpendicular directions parallel to the freezing surface of the unidirectional freezing in step S1) as the x-axis and y-axis, respectively, firstly, unidirectional pre-compressing is performed on the unidirectional porous ceramic green body along the x-axis direction, and then secondary compression is performed on the unidirectional pre-compressed green body along the y-axis direction; the compression amount of the unidirectional pre-compression is 5% to 50% of the width of the unidirectional porous ceramic green body in the x-axis direction, and the compression amount of the secondary compression is 10% to 70% of the width of the unidirectional porous ceramic green body in the y-axis direction;

[0010] The pressure for isostatic compaction is 30 MPa to 400 MPa;

[0011] S3) The densified green body obtained in step S2) is degreased and sintered to obtain a single-oriented microporous ceramic framework.

[0012] S4) The second phase material and the unidirectional microporous ceramic skeleton obtained in step S3) are combined to obtain a fatigue-resistant biomimetic ceramic composite material; the second phase material is selected from polymer materials or metal materials.

[0013] This invention first involves sequentially subjecting a ceramic slurry to unidirectional freezing and freeze-drying. The ceramic slurry of this invention comprises: ceramic powder, binder, surfactant, and water. The total mass percentage of the ceramic powder is 10 wt% to 80 wt%, the solid mass percentage of the binder is 0.1 wt% to 10 wt% of the ceramic powder mass, and the mass percentage of the surfactant is 0.1 wt% to 10 wt% of the ceramic powder mass. In some embodiments of this invention, the ceramic slurry further includes 0.1 vol% to 10 vol% of a defoamer. The ceramic slurry of this invention is prepared by the following method: mixing and ball-milling ceramic powder, binder, surfactant, and water in a certain proportion to obtain a ceramic slurry. In some embodiments of this invention, mixing and ball-milling ceramic powder, binder, surfactant, and water in a certain proportion to obtain a water-soluble ceramic slurry; adding a defoamer to the water-soluble ceramic slurry, stirring, and then vacuum defoaming to obtain a uniform ceramic slurry. The ball milling speed described in this invention is 150 rpm to 500 rpm, and the ball milling time is 6 h to 48 h. The vacuum defoaming time described in this invention is 5 min to 30 min.

[0014] The ceramic powder of this invention preferably includes one or more of the following: hydroxyapatite, β-tricalcium phosphate, bioactive glass, wollastonite, diopside, zirconia powder, alumina powder, silica powder, zirconia-toughened alumina powder (ZTA), yttrium oxide powder, silicon nitride powder, aluminum nitride powder, boron nitride powder, silicon carbide powder, carbide powder, silicon boride powder, carbon boride powder, aluminum silicide powder, and molybdenum silicide powder; the binder preferably includes: sodium carboxymethyl cellulose, methyl cellulose, etc. The surfactant comprises one or more of the following: hydroxyethyl cellulose, bacterial cellulose, lignocellulose, polyvinyl alcohol, chitosan, sodium alginate, polyethylene glycol, polyacrylic acid, aluminum dihydrogen phosphate, and magnesium phosphate; the surfactant preferably comprises one or more of the following: sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, sodium lignosulfonate, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, polyethylene glycol octylphenyl ether, fatty alcohol polyoxyethylene ether, sorbitan fatty acid ester, and polyoxyethylene sorbitan fatty acid ester.

[0015] The defoamer described in this invention is selected from one or more of the following: organosilicon defoamers, polyether-modified silicone defoamers, polyether defoamers, and mineral oil defoamers.

[0016] This invention first involves subjecting a ceramic slurry to unidirectional freezing and freeze-drying sequentially. Specifically, the ceramic slurry is unidirectionally frozen in a mold, and after complete crystallization, it is demolded and freeze-dried to obtain a unidirectional porous ceramic green body. The freezing rate of the unidirectional freezing in this invention is -1℃ / min to -10℃ / min, and an appropriate freezing rate is beneficial to the orientation degree of the unidirectional porous ceramic green body; the unidirectional freezing time is 24 h to 72 h.

[0017] Before unidirectional freezing, the freezing base plate of the mold is pre-cooled to 0~-50℃. The freezing base plate is made of materials including copper, aluminum, stainless steel, and other hard materials with smooth surfaces and excellent thermal conductivity. Its function is to rapidly transfer the temperature of the cold source, thereby stabilizing the generation of a unidirectional temperature gradient. The freezing base plate uses one of the following methods: liquid nitrogen cooling, dry ice cooling, compressor cooling, and semiconductor cooling. The mold can be prepared by casting and injection molding, enabling mass production of frozen ceramic blanks. Specifically, the mold is a mold with a columnar through-hole structure, more specifically, a soft polymer mold; more specifically, the soft polymer mold includes one of silicone rubber, polyurethane elastomer, rubber, polytetrafluoroethylene, and polyvinyl chloride elastomer. In some embodiments of the invention, the mold is a soft polymer mold with a length and width of 5×5 mm~1500×1500 mm and a height of 5 mm~50 mm.

[0018] The unidirectional porous ceramic green body obtained by this invention has micropores with a diameter of 5 μm to 60 μm, preferably 10 μm to 35 μm, with the pore direction perpendicular to the freezing surface direction, and the pore structure is a unidirectional pore structure. The ceramic phase of the unidirectional porous ceramic green body obtained by this invention imparts material strength, and the porosity of the unidirectional porous ceramic green body is 30% to 95%, preferably 60% to 85%.

[0019] After obtaining a unidirectional porous ceramic green body, this invention performs bi-radial densification or isostatic pressing densification on the obtained unidirectional porous ceramic green body to obtain a densified green body. Specifically, the bi-radial densification of this invention includes: taking the pore direction of the unidirectional porous ceramic green body as the z-axis, and two mutually perpendicular directions parallel to the freezing surface of the unidirectional freezing in step S1) as the x-axis and y-axis, respectively, first performing unidirectional pre-compression along the x-axis direction on the unidirectional porous ceramic green body, and then performing secondary compression along the y-axis direction on the unidirectionally pre-compressed green body; the compression amount of the unidirectional pre-compression is 5%~50% of the width of the unidirectional porous ceramic green body in the x-axis direction; the compression amount of the secondary compression is 10%~7% of the width of the unidirectional porous ceramic green body in the y-axis direction. 0%; Preferably, the x-axis dimension and y-axis dimension of the unidirectional porous ceramic green body obtained in step S1) are the same. First, the unidirectional porous ceramic green body is pre-compressed along the x-axis, and the compression amount of the unidirectional pre-compression is 20%~40% of the width of the unidirectional porous ceramic green body in the x-axis direction; then, the green body after unidirectional pre-compression is secondarily compressed along the y-axis, and the compression amount of the second compression is 45%~55% of the width of the unidirectional porous ceramic green body in the y-axis direction. The x-axis dimension and y-axis dimension of the densified green body obtained in step S2) are the same. More specifically, the second compression is performed in a lobed mold, the length of the inner cavity of the lobed mold is 1~2 times the z-axis dimension of the unidirectional porous ceramic green body after unidirectional pre-compression, and the width of the inner cavity of the lobed mold is consistent with the x-axis dimension of the obtained densified green body. The isostatic pressing densification method described in this invention does not require control of the axial compression amount; only the pressure range applied during densification needs to be controlled to obtain a densified green body. Specifically, the x-axis dimension and y-axis dimension of the unidirectional porous ceramic green body obtained in step S1) are the same, and the obtained unidirectional porous ceramic green body is subjected to isostatic pressing densification. The pressure of the isostatic pressing densification is 30 MPa to 400 MPa.

[0020] In steps S1) and S2), this invention prepares a porous ceramic framework from ceramic slurry using unidirectional cryogenic casting and densification techniques. First, unidirectional cryogenic casting is used to create a framework with a unidirectional macroporous structure. Then, bi-radial compression or radial isostatic pressing is used to cause the macropores to collapse radially into uniformly distributed unidirectional micropores. Densification increases the ceramic content in the material to achieve the highest possible strength. Furthermore, the uniformly distributed unidirectional micropores constructed in the ceramic are subsequently filled with a low-modulus second phase (polymer or metal) through vacuum-assisted impregnation, resulting in a biomimetic organic-inorganic microstructure. This microstructure can significantly improve the material's fracture toughness and energy dissipation capacity through interfacial debonding, bridging, and crack deflection. Therefore, it can improve the material's fatigue performance by resisting fatigue crack propagation.

[0021] After obtaining a densified green body, this invention involves debinding and sintering the densified green body to obtain a unidirectional microporous ceramic framework. The maximum debinding and sintering temperature is 1000℃~2400℃, and the debinding and sintering time is 4h~36h. The unidirectional microporous ceramic framework obtained by this invention has uniformly distributed micropores inside. Through densification, the macropores of the prepared green body framework collapse radially, resulting in a final pore diameter of 1 μm~20 μm, preferably 1 μm~4 μm. In some embodiments of this invention, the unidirectional microporous ceramic framework obtained by this invention is a rod, and the direction of its internal pores is parallel to the axial direction of the rod.

[0022] This invention obtains a unidirectional microporous ceramic framework, and then combines a second-phase material with the obtained unidirectional microporous ceramic framework to obtain a fatigue-resistant biomimetic ceramic composite material; the second-phase material is selected from polymer materials or metallic materials. In this invention, after the second-phase material is combined with the unidirectional microporous ceramic framework, a second phase with high toughness or even low modulus and high toughness is further introduced into the microporous structure. The second phase distributed in the unidirectional microporous structure of the unidirectional microporous ceramic framework provides toughness to the material and plays a role in toughening and inhibiting crack propagation. The second phase material of this invention specifically includes polymer materials or metallic materials with a melting point of 50°C to 800°C; the polymer materials include one of the following: epoxy resin, unsaturated polyester resin, phenolic resin, cyanate ester resin, bismaleimide resin, polymethyl methacrylate, polypropylene, polyetheretherketone, polystyrene, polyvinyl chloride, polyethylene, polyimide, polyetherimide, polyacrylamide, and polylactic acid; the metallic materials with a melting point of 50°C to 800°C include one or more of the following: copper, aluminum, magnesium, tin, lead, zinc, Wood's alloy, zinc-aluminum alloy, zinc-copper alloy, copper-tin alloy, nickel-copper alloy, magnesium-aluminum alloy, and Babbitt metal.

[0023] In this invention, if the second phase material is a polymer material, the composite process is as follows: the unidirectional microporous ceramic framework obtained in step S3) is interface-modified using a coupling agent, then vacuum-impregnated in a monomer polymerization solution of the polymer material, and then cured. First, the obtained unidirectional microporous ceramic framework is interface-modified sequentially using a mixed solution of concentrated H2SO4 and H2O2 and a mixed solution of coupling agent and alcohol. The interface modification in this invention involves vacuum impregnation followed by immersion treatment; specifically: vacuum impregnation for 10-30 minutes, followed by immersion treatment for 10-16 hours. In the interface modification of this invention, before immersion treatment, the vacuum-impregnated unidirectional microporous ceramic framework is washed until the pH of the washing solution is neutral, preferably 6-10 times with deionized water until the pH of the washing solution is neutral; after immersion treatment, the immersion-treated unidirectional microporous ceramic framework is washed, preferably 2-4 times with anhydrous ethanol. The mixed solution of concentrated H2SO4 and H2O2 in this invention is a mixed solution of concentrated H2SO4 and H2O2 with a mass ratio of 1:(0.8~1.2); the mixed solution of coupling agent and alcohol is a mixed solution of coupling agent and alcohol with a volume ratio of 1:(4~20). The coupling agent of this invention includes one of silane coupling agents, titanate coupling agents, aluminate coupling agents, borate coupling agents, and phosphate coupling agents, and its function is to improve the adhesion of the interface between the ceramic phase and the resin phase through chemical bonding. The alcohol of this invention is preferably ethanol.

[0024] After interface modification of the obtained unidirectional microporous ceramic framework, the interface-modified unidirectional microporous ceramic framework is vacuum impregnated in a monomer polymerization solution of resin material, and then cured to obtain a fatigue-resistant biomimetic ceramic composite material. Those skilled in the art can select different curing methods based on different polymer material types using conventional techniques in the field. In some embodiments of the present invention, the interface-modified unidirectional microporous ceramic framework is vacuum impregnated in a monomer polymerization solution of polymer material for 20 min to 40 min. The vacuum-impregnated unidirectional microporous ceramic framework is then removed and placed under mild conditions for pre-curing. Further curing is performed by increasing the polymerization environment parameters. After curing, excess resin is removed to obtain the fatigue-resistant biomimetic ceramic composite material. The monomer polymerization solution of the polymer material includes polymethyl methacrylate monomer and an initiator, wherein the initiator accounts for 0.4% to 0.6% of the mass of the polymethyl methacrylate monomer.

[0025] In this invention, if the second phase material is a metallic material, the composite process involves: vacuum impregnating the unidirectional microporous ceramic framework obtained in step S3) with a molten metallic material. Specifically, the metallic material and the obtained unidirectional microporous ceramic framework are simultaneously placed in a vacuum pressure metal casting apparatus, and the metallic material is heated to melt, causing the unidirectional microporous ceramic framework to undergo vacuum impregnation in the molten metallic material. This vacuum impregnation allows the molten metallic material to penetrate into the unidirectional microporous ceramic framework. After cooling, excess metal is removed to obtain a fatigue-resistant biomimetic ceramic composite material.

[0026] This invention also provides a fatigue-resistant biomimetic ceramic composite material obtained by any of the preparation methods described above. The main component of the fatigue-resistant biomimetic ceramic composite material obtained by this invention is a ceramic phase, with a volume percentage of 60% to 95%. The ceramic phase in the fatigue-resistant biomimetic ceramic composite material of this invention provides strength, and combined with a second phase distributed in a unidirectional microporous structure that provides toughness, it exhibits excellent fatigue resistance. Specifically, the static bending strength of the fatigue-resistant biomimetic ceramic composite material of this invention can reach 100 MPa to 1000 MPa; the axial compressive strength of the fatigue-resistant biomimetic ceramic composite material can reach 0.8 GPa to 2.4 GPa; and the fatigue limit ratio of the fatigue-resistant biomimetic ceramic composite material is 60% to 90% or even 70% to 90%, which is 20% to 400% higher than that of the control group densified ceramic. In some embodiments of this invention, the macroscopic structure of the fatigue-resistant biomimetic ceramic composite material obtained by this invention is preferably a long rod-shaped structural component, which, unlike plates, has radial bending resistance and axial compressive strength.

[0027] This invention also provides the application of the fatigue-resistant biomimetic ceramic composite material obtained by any of the above-described preparation methods in the preparation of one or more dental implants, orthopedic internal fixation screws, precision instrument bolts, and robot structural components. The preparation method provided by this invention overcomes the shortcomings of existing technologies in effectively improving the fatigue resistance of ceramic materials. Furthermore, this method is simple and can be scaled up for production, enabling the rapid preparation of ceramic composite rods with high fatigue resistance, exhibiting radial isotropy and a high fatigue limit approaching 70-90% of their static strength. In addition, this material has good machinability and can be used in dental implants, orthopedic internal fixation screws, precision instrument bolts, robot structural components, etc.

[0028] This invention provides a fatigue-resistant biomimetic ceramic composite material, its preparation method, and its applications. The preparation method provided by this invention is based on the biomimetic design principles of unidirectional microporous structures and soft-hard phase interfaces. Through a series of simple process steps combining unidirectional freeze-drying, radial pressure-assisted densification, interface modification, and second-phase vacuum-assisted impregnation, a uniformly distributed unidirectional porous structure is first formed within the ceramic material. Then, the porous structure is further transformed into a unidirectional microporous structure, and a second phase with high toughness, or even low modulus and high toughness, is introduced. This rapidly constructs a ceramic composite material with a coaxially oriented second phase. These second phases, oriented within the ceramic framework, form damage isolation micro-regions, endowing the composite material with a highly efficient energy dissipation mechanism across scales, effectively inhibiting the initiation and propagation of fatigue cracks. Simultaneously, under cyclic dynamic loading, it can rapidly dissipate overall energy, avoiding or slowing down the initiation of fatigue cracks. At the submicron scale, the low-modulus second phase and weak interfaces can effectively induce fatigue crack deflection and bridging, while at the nanoscale, the debonding of the second phase from the ceramic framework interface can also dissipate energy for crack tip propagation. Compared with existing technologies, the fatigue-resistant biomimetic composite ceramic material prepared by this invention has radial isotropy and a fatigue limit ratio of 60%~90% or even 70%~90%, solving the problem that previous technologies could not prepare ceramic materials with high fatigue limits. Attached Figure Description

[0029] Figure 1 These are SEM images of the cross-sectional morphology of the ceramic skeleton in Embodiment 1, Comparative Example 4, and Comparative Example 5 of the present invention.

[0030] Figure 2 The Vickers indentation morphology of the ceramic materials finally obtained in Example 1 and Comparative Example 1 of this invention is shown in the diagram.

[0031] Figure 3 The Vickers indentation morphology of the ceramic materials finally obtained in Example 2 and Comparative Example 2 of this invention are shown.

[0032] Figure 4 The Vickers indentation morphology of the ceramic materials finally obtained in Example 3 and Comparative Example 3 of the present invention is shown.

[0033] Figure 5 The bending stress-strain curves of the ceramic materials finally obtained in Embodiment 1, Comparative Example 4, and Comparative Example 5 of the present invention are shown.

[0034] Figure 6 This is the axial compressive stress-strain curve of the ceramic material finally obtained in Embodiment 1 of the present invention;

[0035] Figure 7 The image shows the SN curves of the ceramic materials finally obtained in Example 1 and Comparative Example 1 of this invention.

[0036] Figure 8The images show the low-cycle fatigue fracture surface SEM images of the ceramic skeleton of the ceramic materials finally obtained in Embodiment 1 and Comparative Example 1 of this invention.

[0037] Figure 9 This is a display image of the ceramic material and its processed sample obtained in Example 1. Detailed Implementation

[0038] This invention discloses a fatigue-resistant biomimetic ceramic composite material, its preparation method, and its application. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments, and those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0039] The present invention will be further described below with reference to the embodiments:

[0040] Example 1

[0041] The preparation of the biomimetic zirconia ceramic resin composite material is as follows:

[0042] Preparation of zirconia ceramic slurry: At room temperature, 40 g of zirconia powder, 40 g of 2 wt% polyvinyl alcohol solution, 20 g of deionized water, and 0.4 g of sodium dodecyl sulfate were added to a ball mill jar. The slurry was ball-milled at 200 rpm for 12 h. After ball milling, 0.2 g of defoamer was added, and the mixture was thoroughly stirred and then defoamed under vacuum for 20 min to obtain a uniform ceramic slurry.

[0043] Unidirectional freezing of ceramic slurry: Copper blocks were pre-cooled to -5°C with liquid nitrogen, and the ceramic slurry was poured into a silicone rubber mold for unidirectional freezing. The freezing rate was controlled at -2°C / min. After the slurry was completely crystallized, it was demolded and freeze-dried for 48 hours. After freeze-drying, a porous ceramic green body with unidirectional orientation was obtained.

[0044] Densification of ceramic green bodies: The ceramic green body was cut into uniform blocks of 10.87 mm × 10.87 mm × 35 mm. Using the direction parallel to the micropores as the z-axis, and two mutually perpendicular directions parallel to the freezing surface as the x-axis and y-axis, the green body was first unidirectionally compressed along the x-axis by 30%. Then, the pre-compressed green body was placed into a lobed mold (the width and length of the inner cavity were 5 mm and 35 mm, respectively), and compressed a second time along the y-axis by 54%, resulting in a densified green body.

[0045] Sintering of ceramic green body: The densified green body is further sintered under normal pressure. The sintering program is as follows: 240 min at room temperature to 600℃, hold for 120 min, 180 min to 1000℃, hold for 60 min, 360 min to 1500℃, hold for 180 min, 180 min to 1200℃, and the program ends. After sintering, a unidirectional microporous ceramic framework I is obtained.

[0046] Modification and polymer impregnation of unidirectional microporous ceramic framework I: Mixed solution I was prepared by mixing concentrated H2SO4 and H2O2 at a mass ratio of 1~1. Unidirectional microporous ceramic framework I was placed in mixed solution I and vacuum impregnated for 20 min. After impregnation, it was soaked for 12 h. The ceramic framework was then removed and washed 8 times with deionized water. The pH of the washing solution was adjusted to neutral. Mixed solution II was prepared by mixing coupling agent and anhydrous ethanol at a volume ratio of 1~1. The ceramic framework was placed in mixed solution II and vacuum impregnated for 20 min. After impregnation, it was soaked for 12 h. It was washed 3 times with anhydrous ethanol and dried to obtain interface-modified unidirectional microporous ceramic framework II.

[0047] A polymerization solution was prepared by mixing methyl methacrylate and 2,2-azobisisobutyronitrile at a fixed ratio of 1:0.5%. The unidirectional microporous ceramic skeleton II was placed in the polymerization solution and vacuum impregnated for 30 min. Then, the impregnated skeleton was removed and cured in a 40℃ water bath for 48 h. After water bath curing, it was transferred to an 80℃ oven for curing for 12 h. After complete curing, the excess resin was removed to obtain the ceramic resin composite material.

[0048] Example 2

[0049] The preparation of biomimetic alumina ceramic resin composite material is as follows:

[0050] Preparation of alumina ceramic slurry: At room temperature, 26.96 g of alumina powder, 40 g of 2 wt% polyvinyl alcohol solution, 20 g of deionized water, and 0.4 g of sodium dodecyl sulfate were added to a ball mill jar. The slurry was ball-milled at 200 rpm for 12 h. After ball milling, 0.2 g of defoamer was added, and the mixture was thoroughly stirred and then defoamed under vacuum for 20 min to obtain a uniform ceramic slurry.

[0051] One-way freezing of ceramic slurry: Same as in Example 1.

[0052] Densification of ceramic green body: Same as in Example 1.

[0053] Sintering of ceramic green body: The densified green body is further sintered under normal pressure. The sintering program is as follows: 320 min at room temperature to 1600℃, hold for 180 min, and then the program ends. After sintering, a unidirectional microporous ceramic framework I is obtained.

[0054] Mono-oriented microporous ceramic framework I modification and polymer impregnation: Same as in Example 1, finally obtaining ceramic resin composite material.

[0055] Example 3

[0056] The preparation of the biomimetic ZTA ceramic resin composite material is as follows:

[0057] ZTA ceramic slurry preparation: At room temperature, 28.73 g of ZTA powder, 40 g of 2 wt% polyvinyl alcohol solution, 20 g of deionized water, and 0.4 g of sodium dodecyl sulfate were added to a ball mill jar. The slurry was ball-milled at 200 rpm for 12 h. After ball milling, 0.2 g of defoamer was added, and the mixture was thoroughly stirred and then defoamed under vacuum for 20 min to obtain a homogeneous ceramic slurry.

[0058] One-way freezing of ceramic slurry: Same as in Example 1.

[0059] Densification of ceramic green body: Same as in Example 1.

[0060] Sintering of ceramic blanks: Same as in Example 1.

[0061] Mono-oriented microporous ceramic framework I modification and polymer impregnation: Same as in Example 1, finally obtaining ceramic resin composite material.

[0062] Comparative Example 1

[0063] The preparation of dense zirconia ceramics is as follows:

[0064] Preparation of zirconia ceramic slurry: Same as in Example 1.

[0065] One-way freezing of ceramic slurry: Same as in Example 1.

[0066] Densification of ceramic green bodies: The ceramic green body was cut into uniform blocks of 10.87 mm × 10.87 mm × 35 mm. Using the direction parallel to the micropores as the z-axis, and two mutually perpendicular directions parallel to the freezing surface as the x-axis and y-axis, the green body was first unidirectionally compressed along the x-axis by 30%. Then, the pre-compressed green body was placed into a lobed mold (the width and length of the inner cavity were 5 mm and 35 mm, respectively), and compressed a second time along the y-axis by 70%, resulting in a densified green body.

[0067] Sintering of ceramic blanks: The sintering procedure is the same as in Example 1, and a dense pure zirconia ceramic block is finally obtained.

[0068] Comparative Example 2

[0069] The preparation of dense alumina ceramics is as follows:

[0070] Preparation of alumina ceramic slurry: Same as in Example 2.

[0071] One-way freezing of ceramic slurry: Same as in Example 1.

[0072] Densification of ceramic green body: Same as comparative example 1.

[0073] Sintering of ceramic blanks: The sintering procedure is the same as in Example 2, and a dense pure zirconia ceramic block is finally obtained.

[0074] Comparative Example 3

[0075] The preparation of dense ZTA ceramics is as follows:

[0076] ZTA ceramic slurry preparation: Same as in Example 3.

[0077] One-way freezing of ceramic slurry: Same as in Example 1.

[0078] Densification of ceramic green body: Same as comparative example 1.

[0079] Sintering of ceramic blanks: The sintering procedure is the same as in Example 1, and a dense ZTA ceramic block is finally obtained.

[0080] Comparative Example 4

[0081] The preparation of the undensified zirconia preform framework is as follows:

[0082] Preparation of zirconia ceramic slurry: Same as in Example 1.

[0083] One-way freezing of ceramic slurry: Same as in Example 1.

[0084] Sintering of ceramic green body: The sintering procedure is the same as in Example 1. After completion, a zirconia green body skeleton with a macroporous structure can be obtained.

[0085] Comparative Example 5

[0086] The preparation of the zirconia-densified ceramic framework is as follows:

[0087] Preparation of zirconia ceramic slurry: Same as in Example 1.

[0088] One-way freezing of ceramic slurry: Same as in Example 1.

[0089] Densification of ceramic green body: Same as in Example 1;

[0090] Sintering of ceramic green body: Same as in Example 1, after which a zirconia ceramic skeleton with a unidirectional microporous structure can be obtained.

[0091] Test example:

[0092] The cross-sectional SEM morphology of the ceramic skeletons obtained in Example 1, Comparative Example 4, and Comparative Example 5 was analyzed, and the results are as follows: Figure 1 As shown, Figure 1These are SEM images of the cross-sectional morphology of the ceramic skeleton in Embodiment 1, Comparative Example 4, and Comparative Example 5 of the present invention. Comparative Example 4 and Comparative Example 5 show the change in the sintered skeleton from porous to microporous before and after densification. Embodiment 1 shows that the second phase can completely fill the micropores and has a good interface with the ceramic.

[0093] The Vickers indentation morphology of the ceramic materials obtained in Example 1 and Comparative Example 1 was analyzed, and the results are as follows: Figure 2 As shown, Figure 2 These are Vickers indentation morphology images of the ceramic materials finally obtained in Example 1 and Comparative Example 1 of the present invention. Figure 2 The two figures at the top and middle show the Vickers indentation morphology of the ceramic material obtained in Comparative Example 1 of this invention at different scales. Figure 2 The two figures at the bottom center show the Vickers indentation morphology of the final ceramic material obtained in Embodiment 1 of the present invention at different scales. Figure 2 In Comparative Example 1, the Vickers indentation at each of the four corners exhibits obvious main cracks, demonstrating poor resistance to crack propagation. In Example 1, the Vickers indentation at each of the four corners exhibits less noticeable microcracks, demonstrating strong resistance to crack propagation.

[0094] The Vickers indentation morphology of the ceramic materials obtained in Example 2 and Comparative Example 2 was analyzed, and the results are as follows: Figure 3 As shown, Figure 3 These are Vickers indentation morphology images of the ceramic materials finally obtained in Example 2 and Comparative Example 2 of the present invention. Figure 3 The two figures at the top and middle show the Vickers indentation morphology of the final ceramic material obtained in Comparative Example 2 of this invention at different scales. Figure 3 The two figures at the bottom center show the Vickers indentation morphology of the final ceramic material obtained in Embodiment 2 of the present invention at different scales. Figure 3 In Comparative Example 2, the Vickers indentation edge exhibits a prominent main crack, demonstrating poor resistance to crack propagation. In Example 2, the Vickers indentation edge shows less noticeable microcracks, indicating strong resistance to crack propagation.

[0095] The Vickers indentation morphology of the ceramic materials obtained in Example 3 and Comparative Example 3 was analyzed, and the results are as follows: Figure 4 As shown, Figure 4 These are Vickers indentation morphology images of the final ceramic materials obtained in Embodiment 3 and Comparative Example 3 of the present invention. Figure 4 The two figures at the top and middle show the Vickers indentation morphology of the final ceramic material obtained in Comparative Example 3 of this invention at different scales. Figure 4 The two figures at the bottom center show the Vickers indentation morphology of the final ceramic material obtained in Embodiment 3 of the present invention at different scales. Figure 4 In Comparative Example 3, the Vickers indentation exhibits obvious main cracks at its four corners, demonstrating poor resistance to crack propagation. In Example 2, the Vickers indentation edges show less noticeable microcracks, indicating strong resistance to crack propagation.

[0096] Bending stress-strain curve analysis was performed on the ceramic materials finally obtained in Example 1, Comparative Example 4, and Comparative Example 5. The results are as follows: Figure 5 As shown, Figure 5 The figures show the bending stress-strain curves of the final ceramic materials obtained in Examples 1, 4, and 5 of this invention. Comparative Examples 4 and 5 show the bending stress-strain curves of the ceramic skeleton before and after densification. The bending strength of Comparative Example 5 is significantly enhanced after densification. Example 1 is the final ceramic-resin composite material, which has a further improved bending strength, demonstrating that densification and the second composite strategy have excellent performance improvement effects.

[0097] The axial compressive stress-strain curve of the ceramic material finally obtained in Example 1 was analyzed, and the results are as follows: Figure 6 As shown, Figure 6 This is the axial compressive stress-strain curve of the ceramic material finally obtained in Example 1 of the present invention. The coaxial orientation of the ceramic composite material prepared in Example 1 gives it an excellent axial compressive strength of 1.42 GPa.

[0098] SN curve analysis was performed on the ceramic materials obtained in Example 1 and Comparative Example 1. The fatigue limit ratio was the normalized percentage of the ratio of fatigue limit to static strength. The results are as follows: Figure 7 As shown, Figure 7 The image shows the SN curves of the final ceramic materials obtained in Example 1 and Comparative Example 1 of this invention. The fatigue limit ratio of Example 1 is significantly higher than that of Comparative Example 1. Under the same fatigue limit ratio, the composite ceramic has a lifespan 100 to 1000 times longer than that of pure ceramic.

[0099] Low-cycle fatigue fracture morphology analysis was performed on the ceramic materials obtained in Example 1 and Comparative Example 1. The results are as follows: Figure 8 As shown, Figure 8 The images show the low-cycle fatigue fracture surface SEM images of the ceramic skeletons of the ceramic materials finally obtained in Example 1 and Comparative Example 1 of this invention. The composite ceramic prepared in Comparative Example 1 has a rougher fracture surface than that in Comparative Example 1, indicating that the composite ceramic can effectively resist crack propagation and avoid brittle fracture similar to that in Comparative Example 1.

[0100] The ceramic material obtained in Example 1 was processed into a sample, such as... Figure 9 As shown, Figure 9 This is a diagram illustrating the final ceramic material obtained in Example 1 and its processed sample. The processed sample is a dental implant. Due to the reduction of the structural modulus by the second-phase composite, Example 1 exhibits good processing performance.

[0101] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a fatigue-resistant biomimetic ceramic composite material, characterized in that, Includes the following steps: S1) The ceramic slurry is subjected to unidirectional freezing and freeze-drying in sequence to obtain a unidirectional porous ceramic green body; S2) The unidirectional porous ceramic green body obtained in step S1) is subjected to bi-radial densification or isostatic pressing densification to obtain a densified green body. The bi-radial densification specifically includes: taking the pore direction of the unidirectional porous ceramic green body as the z-axis, and taking the two mutually perpendicular directions parallel to the freezing surface of the unidirectional freezing in step S1) as the x-axis and y-axis, respectively, firstly, unidirectional pre-compressing is performed on the unidirectional porous ceramic green body along the x-axis direction, and then secondary compression is performed on the unidirectional pre-compressed green body along the y-axis direction; the compression amount of the unidirectional pre-compression is 5% to 50% of the width of the unidirectional porous ceramic green body in the x-axis direction, and the compression amount of the secondary compression is 10% to 70% of the width of the unidirectional porous ceramic green body in the y-axis direction; The pressure for isostatic compaction is 30 MPa to 400 MPa; S3) The densified green body obtained in step S2) is degreased and sintered to obtain a single-oriented microporous ceramic framework. S4) The second phase material and the unidirectional microporous ceramic skeleton obtained in step S3) are combined to obtain a fatigue-resistant biomimetic ceramic composite material; the second phase material is selected from polymer materials or metal materials.

2. The preparation method according to claim 1, characterized in that, In step S1), the freezing rate of the unidirectional freezing is -1℃ / min to -10℃ / min; The freeze-drying time is 24 h to 72 h.

3. The preparation method according to claim 1, characterized in that, In step S1), the pore diameter of the obtained unidirectional porous ceramic green body is 5 μm to 60 μm; The porosity of the obtained unidirectional porous ceramic green body is 30%~95%.

4. The preparation method according to claim 1, characterized in that, In step S2), the compression amount of the unidirectional pre-compression in the bi-radial densification is 20% to 40% of the width of the unidirectional porous ceramic green body in the x-axis direction, and the compression amount of the secondary compression is 45% to 55% of the width of the unidirectional porous ceramic green body in the y-axis direction. The x-axis dimension and y-axis dimension of the unidirectional porous ceramic green body obtained in step S1) are the same; the x-axis dimension and y-axis dimension of the densified green body obtained in step S2) are the same.

5. The preparation method according to claim 1, characterized in that, In step S2), the secondary compression is performed in a lobed mold. The length of the inner cavity of the lobed mold is 1 to 2 times the z-axis dimension of the unidirectional porous ceramic blank after unidirectional pre-compression, and the width of the inner cavity of the lobed mold is consistent with the x-axis dimension of the obtained densified blank.

6. The preparation method according to claim 1, characterized in that, In step S3), the average pore diameter of the obtained unidirectional microporous ceramic skeleton is 0.5 μm to 20 μm.

7. The preparation method according to claim 1, characterized in that, In step S4), the second phase material includes a polymer material or a metal material; If the second phase material is a polymer material, the composite process specifically involves: modifying the interface of the unidirectional microporous ceramic framework obtained in step S3) using a coupling agent, then vacuum impregnating it in a monomer polymerization solution of the polymer material, and finally curing it. If the second phase material is a metallic material, the composite process specifically involves: vacuum impregnating the unidirectional microporous ceramic framework obtained in step S3) in a molten metallic material.

8. The preparation method according to claim 1, characterized in that, In step S1), the ceramic slurry comprises: ceramic powder, binder, surfactant, and water. The total mass percentage of the ceramic powder is 10 wt% to 80 wt%, the solid mass percentage of the binder is 0.1 wt% to 10 wt% of the ceramic powder, and the mass percentage of the surfactant is 0.1 wt% to 10 wt% of the ceramic powder. The ceramic powder includes one or more of the following: hydroxyapatite, β-tricalcium phosphate, bioactive glass, wollastonite, diopside, zirconia powder, alumina powder, silica powder, zirconia-toughened alumina powder, yttrium oxide powder, silicon nitride powder, aluminum nitride powder, boron nitride powder, silicon carbide powder, carbide powder, silicon boride powder, boronized carbon powder, aluminum silicide powder, and molybdenum silicide powder. The binder includes one or more of the following: sodium carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, bacterial cellulose, lignocellulose, polyvinyl alcohol, chitosan, sodium alginate, polyethylene glycol, polyacrylic acid, aluminum dihydrogen phosphate, and magnesium phosphate; The surfactant includes one or more of the following: sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, sodium lignosulfonate, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, polyethylene glycol octylphenyl ether, fatty alcohol polyoxyethylene ether, sorbitan fatty acid ester, and polyoxyethylene sorbitan fatty acid ester. In step S4), the second phase material includes a polymer material or a metal material with a melting point of 50°C to 800°C; The polymer material includes one of the following: epoxy resin, unsaturated polyester resin, phenolic resin, cyanate ester resin, bismaleimide resin, polymethyl methacrylate, polypropylene, polyetheretherketone, polystyrene, polyvinyl chloride, polyethylene, polyimide, polyetherimide, polyacrylamide, and polylactic acid. The metallic materials with a melting point of 50℃ to 800℃ include one or more of the following: copper, aluminum, magnesium, tin, lead, zinc, Wood's alloy, zinc-aluminum alloy, zinc-copper alloy, copper-tin alloy, nickel-copper alloy, magnesium-aluminum alloy, and Babbitt alloy.

9. The fatigue-resistant biomimetic ceramic composite material obtained by any of the preparation methods described in claims 1 to 8.

10. The application of the fatigue-resistant biomimetic ceramic composite material obtained by any of the preparation methods described in claims 1 to 8 in the preparation of one or more dental implants, orthopedic internal fixation screws, precision instrument bolts, and robot structural components.

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