Shape memory phenolic aldehyde composite material capable of being vitrified in air and space as well as preparation method and application of shape memory phenolic aldehyde composite material

Abstract

The invention provides an aerospace ceramic shape memory phenolic composite material and a preparation method and application thereof, and relates to the technical field of aerospace functional composites.The preparation method comprises the steps that S1, a shape memory phenolic resin prepolymer, ceramic powder and blackening filler are mixed, and a mixture is obtained; and S2, sequentially heating and curing the mixture to obtain the air-space ceramization shape memory phenolic composite material. The composite material provided by the invention can be shaped into a temporary shape through thermal stimulation on the ground, and after the space returns to an initial shape through thermal / laser stimulation, a ceramic locking structure is realized through laser irradiation, and the bearing capacity is improved. The technical problem that a space unfolding structure cannot be fixed after being unfolded is solved, the shape memory ceramic structure has the dual functions of shape memory and ceramic, and the shape memory ceramic structure is suitable for aerospace application scenes such as satellite solar panels and space antennas.

Description

Technical Field

[0001] The present invention relates to the technical field of aerospace functional composite materials, and in particular to a shape-memory phenolic composite material capable of being ceramicized in aerospace, and a preparation method and application thereof. Background Art

[0002] As a branch of smart materials, shape memory polymers (SMPs) offer a novel solution to complex engineering problems. Due to their diverse actuation methods, low cost, ease of processing, and biocompatibility, SMPs have broad applications across multiple disciplines and fields, such as transformable aircraft, smart fabrics, intelligent medical devices, and deployable structures in space.

[0003] Shape memory polymers have been used in the field of deployable structures in space. Currently, these polymers are typically in the form of shape memory epoxy composites. However, these composites exhibit low modulus, poor load-bearing capacity, and potential problems with securing them after deployment, making them difficult to operate in harsh working conditions. Existing shape memory polymers and their composites struggle to maintain their shape for extended periods of time and maintain load-bearing capacity at high temperatures. Therefore, there is an urgent need for a shape memory phenolic composite material that can be ceramicized in aerospace, as well as its preparation method and application. Summary of the Invention

[0004] The embodiments of the present invention provide a shape-memory phenolic composite material that can be ceramicized in space, and its preparation method and application. The composite material has both shape memory function and laser-induced ceramicization capability, solving the problems of insufficient stiffness of traditional shape-memory polymers and lack of deformation ability of ceramic materials.

[0005] In a first aspect, a method for preparing a shape-memory phenolic composite material capable of being ceramicized in space is provided, the method comprising the following steps:

[0006] S1, mixing a shape memory phenolic resin prepolymer with ceramic powder and a blackening filler to obtain a mixture;

[0007] S2. The mixture is heated and cured in sequence to obtain a shape memory phenolic composite material capable of being aerospace-ceramicized.

[0008] Preferably, in step S1, the shape memory phenolic resin prepolymer includes a shape memory boron phenolic resin prepolymer, a shape memory boron phenolic resin derivative prepolymer, a shape memory silicon phenolic resin prepolymer or a shape memory silicon phenolic resin derivative prepolymer.

[0009] Preferably, the glass transition temperature of the aerospace-ceramicizable shape-memory phenolic composite material is 100-150°C.

[0010] Preferably, in step S1, the ceramic powder is one or more of SiO2, Al2O3, ZrO2, and HfO2.

[0011] Preferably, in step S1, the particle size of the ceramic powder is ≤10 μm.

[0012] Preferably, in step S1, the blackening filler is at least one of carbon black and carbon nanotubes.

[0013] More preferably, the absorptivity of the aerospace-ceramicizable shape-memory phenolic composite material in the near-infrared band is ≥95%.

[0014] Preferably, in step S1, the mass fraction of the shape memory phenolic resin prepolymer in the mixture is 40 to 80%;

[0015] The mass fraction of the ceramic powder in the mixture is 18 to 58%.

[0016] Preferably, in step S1, the mass fraction of the blackening filler is 1.5-2%.

[0017] Preferably, in step S1, the mixing is melt stirring or crushing and grinding.

[0018] Preferably, in step S2, the heating temperature is 80-100° C. and the heating time is 2-4 hours;

[0019] The curing adopts step curing.

[0020] Preferably, before step S1, the method further comprises performing a carboxylation pretreatment on the ceramic powder so that the surface of the ceramic powder contains carboxyl functional groups.

[0021] In a second aspect, the present invention further provides a shape-memory phenolic composite material that can be aerospace-ceramicized, which is prepared using the preparation method described in any one of the first aspects above.

[0022] In a third aspect, the present invention also provides an application of a shape-memory phenolic composite material that can be ceramicized in space, comprising: heating the shape-memory phenolic composite material that can be ceramicized in space to above the glass transition temperature on the ground, and shaping the shape-memory phenolic composite material that can be ceramicized in space to have a temporary shape; heating the shape-memory phenolic composite material that can be ceramicized in space with a temporary shape in the air to obtain a shape-memory phenolic composite material that can be ceramicized in space with an initial shape; wherein the volume of the temporary shape is smaller than the volume of the initial shape; and ceramicizing the shape-memory phenolic composite material that can be ceramicized in space with an initial shape in the air to obtain a ceramicized phenolic composite material.

[0023] Preferably, the step of heating the shape-memory phenolic composite material capable of being ceramicized in space and having a temporary shape in the air to obtain the shape-memory phenolic composite material capable of being ceramicized in space and having an initial shape comprises heating the material by means of an electric heating film or laser heating.

[0024] Preferably, a power density of 50 to 200 W / cm is used. 2 The shape memory phenolic composite material with an initial shape that can be ceramicized in the air is irradiated with laser to complete ceramicization.

[0025] More preferably, the laser spot diameter is 0.5 to 5 mm, and the scanning speed is 1 to 10 mm / s.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] The present invention prepares a ceramic shape-memory phenolic composite material by mixing a shape-memory phenolic resin prepolymer, ceramic powder, and blackening filler. It combines the high-temperature resistance (the residual carbon rate is higher than 65% at 1000°C) and ablation resistance (the linear ablation rate is lower than 0.01mm / s) of the phenolic resin. At the same time, the resin cross-linking density is precisely controlled through a step-curing process to achieve a shape transition temperature of ≤150°C. The composite materials have multiple advantages: 1) Easy to shape on the ground: temporary shape shaping can be achieved at medium and low temperatures (120-150°C); 2) Reliable deployment in space: rapid shape recovery can be achieved through low-power heating in the space station environment; 3) High-temperature service capability: high-temperature resistant shape memory phenolic resin provides composite materials with high-temperature resistance and ablation resistance, which is suitable for extreme working conditions such as spacecraft thermal protection components and deformable high-temperature structures; 4) In-situ ceramicization and high ceramicization efficiency: the inorganic elements in the shape memory phenolic resin prepolymer can easily react with ceramic powder at high temperature to generate more ceramic components. In-situ ceramicization can be achieved without introducing other materials, thereby improving the ceramicization efficiency of the composite materials.

[0028] By introducing a blackening filler, the present invention provides a composite material with a higher light-to-heat conversion efficiency, enabling the composite material to undergo laser recovery and laser ceramicization, shortening the response time of the composite material's shape recovery process from minutes to seconds. Laser irradiation can achieve an instantaneous high temperature of 1600°C, causing the resin's pyrolytic carbon to react with the ceramic powder to form a ceramic phase, improving the composite material's load-bearing capacity and overcoming the two main drawbacks of spatially deployed structures: the inability to secure them after deployment and their weak load-bearing capacity.

[0029] The phenolic composite material, which can be ceramicized in space and in space, has a glass transition temperature adjustable between 100°C and 150°C. When the temperature reaches above the glass transition temperature, the storage modulus of the shape-memory boron phenolic resin is less than 70 MPa, making it easy to deform. The phenolic composite material, which can be ceramicized in space and in space, has a fast shape recovery rate, a shape retention rate greater than 95%, and a shape recovery rate greater than 95%. It also exhibits high-temperature resistance, with a carbon residue rate exceeding 65% in a nitrogen environment at 1000°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 This is a flow chart of a method for preparing a shape-memory phenolic composite material capable of being ceramicized in space provided by the present invention;

[0032] Figure 2 The shape recovery and laser ceramicization process of a shape memory phenolic composite material capable of being ceramicized in space provided in Example 1 of the present invention;

[0033] Figure 3 1 is a graph showing the change in loss factor of a shape memory phenolic composite material capable of being ceramicized in space as a function of temperature provided in Example 1 of the present invention;

[0034] Figure 4 1 is a graph showing the change in storage modulus versus temperature of a shape-memory phenolic composite material capable of being ceramicized in space, provided in Example 1 of the present invention;

[0035] Figure 5 1 is a graph showing the change in loss factor of a shape memory phenolic composite material capable of being ceramicized in space as a function of temperature, provided in Example 2 of the present invention;

[0036] Figure 6 1 is a graph showing the change in storage modulus versus temperature of a shape-memory phenolic composite material capable of being ceramicized in space, provided in Example 2 of the present invention;

[0037] Figure 7 This is an infrared curve of a shape memory phenolic composite material capable of being space-ceramicized provided in Example 1 of the present invention after being laser-ceramicized;

[0038] Figure 8This is an XPS curve of a shape memory phenolic composite material capable of being space-ceramicized provided in Example 1 of the present invention after laser ceramicization;

[0039] Figure 9 3 and 4. These are thermogravimetric curves of the aerospace-ceramic shape-memory phenolic composite materials provided in Examples 1 and 2 of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0041] like Figure 1 As shown, a method for preparing a shape memory phenolic composite material that can be ceramicized in space, the preparation method comprises the following steps:

[0042] S1, mixing a shape memory phenolic resin prepolymer with ceramic powder and a blackening filler to obtain a mixture;

[0043] S2. The mixture is heated and cured in sequence to obtain a shape memory phenolic composite material capable of being aerospace-ceramicized.

[0044] In an embodiment of the present invention, a ceramic composite material with multiple functions is prepared by compounding a shape memory inorganic hybrid phenolic resin with a specific inorganic filler. The resin cross-linking network is precisely controlled by a step-curing process, and while retaining the inherent high temperature resistance and ablation resistance of the phenolic resin, the material is given a controllable shape transition temperature. At the same time, convenient ground shaping under medium and low temperature conditions is achieved; rapid shape recovery driven by low power consumption in a space environment is supported; and service capability under extreme high temperature conditions is maintained. Further, by introducing functional fillers, the photothermal conversion efficiency is significantly improved, making laser-driven shape recovery and ceramicization processes possible. The present invention not only greatly shortens the shape response time, but also effectively enhances the material's load-bearing performance through an in-situ ceramicization reaction, fundamentally solving the common problems of difficult fixation and insufficient load-bearing after the spatial structure is unfolded.

[0045] According to some preferred embodiments, in step S1 , the shape memory phenolic resin prepolymer includes a shape memory boron phenolic resin prepolymer, a shape memory boron phenolic resin derivative prepolymer, a shape memory silicon phenolic resin prepolymer, or a shape memory silicon phenolic resin derivative prepolymer.

[0046] It should be noted that the shape memory boron phenolic resin obtained by polymerizing the shape memory boron phenolic resin prepolymer is the shape memory boron phenolic resin recorded in Chinese patent CN118165020A, that is, the shape memory boron phenolic resin prepolymer is obtained by pre-curing the hyperbranched boron phenolic monomer recorded therein under the action of a curing agent by keeping warm at 80°C for 4 hours and at 90°C for 4 hours. At the same time, the foaming problem in the pre-curing process can be alleviated by slow pre-curing in steps; wherein the curing agent is one or more of anhydride curing agent, amine curing agent, inorganic acid curing agent, and synthetic resin oligomer curing agent.

[0047] In the embodiments of the present invention, the shape-memory phenolic resin obtained by polymerizing the selected shape-memory phenolic resin prepolymer is a shape-memory inorganic hybrid phenolic resin, which exhibits high-temperature and ablation resistance. The inorganic elements in the resin readily form more ceramic phases with inorganic fillers under high-temperature conditions, thereby improving the material's ceramic-forming efficiency. The shape-memory phenolic resin has a glass transition temperature of 80 to 120°C.

[0048] According to some preferred embodiments, the glass transition temperature of the aerospace-ceramic shape memory phenolic composite material is 100-150°C (for example, it can be 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C or 150°C).

[0049] According to some preferred embodiments, in step S1, the ceramic powder is one or more of SiO2, Al2O3, ZrO2, and HfO2.

[0050] It should be noted that the choice of ceramic powder can be determined based on application requirements. Specifically, if the application environment is below 1400°C, SiO2 and Al2O3 are selected; if the application environment is above 1400°C but below 2000°C, ZrO2 is selected; and if the application environment is above 2000°C, HfO2 is selected.

[0051] According to some preferred embodiments, in step S1, in order to avoid uneven mixing of ceramic powder due to excessively large particle size, the particle size of the ceramic powder is limited to ≤10 μm (for example, it can be 10 μm, 8 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2 μm, etc.).

[0052] According to some preferred embodiments, before step S1, the ceramic powder is further subjected to carboxylation pretreatment so that the surface of the ceramic powder contains carboxyl functional groups.

[0053] Specifically, the carboxylation pretreatment step of the ceramic powder includes: mixing according to the mass of ceramic powder: strong acid volume = 1g: (10-15) mL, heating it to 80-90°C, reacting for 4-6 hours, and separating it by centrifugation after natural cooling to room temperature (for example, 25°C). After drying, a carboxylated ceramic powder is obtained, and the surface of the ceramic powder contains carboxyl functional groups. In this way, the surface of the shape memory phenolic resin prepolymer is rich in hydroxyl groups, which makes it easier to grow in situ on the surface of the carboxylated ceramic powder. It should be noted that the strong acid is concentrated sulfuric acid, concentrated nitric acid, concentrated hydrochloric acid, and concentrated oxalic acid.

[0054] In an embodiment of the present invention, during the carboxylation pretreatment process, if the amount of strong acid used is too small, it may result in only part of the hydroxyl groups on the surface of the ceramic powder being oxidized to carboxyl groups, insufficient surface active sites, and uneven dispersion in the resin matrix, affecting the mechanical properties of the final prepared composite material; but if the amount of strong acid used is too large, it will destroy the crystal structure or surface morphology of the ceramic powder, thereby introducing an unstable interface and unnecessary side reactions, and even causing degradation of the shape memory phenolic resin prepolymer.

[0055] According to some preferred embodiments, in step S1, the blackening filler is at least one of carbon black and carbon nanotubes.

[0056] According to some preferred embodiments, in step S1, the mass fraction of the blackening filler is 1.5-2% (for example, 1.5%, 1.6%, 1.8% or 2%).

[0057] According to some more preferred embodiments, the absorptivity of the aerospace-ceramicizable shape-memory phenolic composite material in the near-infrared band is ≥95%.

[0058] In an embodiment of the present invention, the mass fraction of the blackening filler does not exceed 2%. The inventors have found that when the mass fraction of the blackening filler is greater than 2%, it will affect the continuity of the shape-memory phenolic resin during the curing process, thereby affecting the deformation ability of the shape-memory phenolic composite material that can be ceramicized in space. At the same time, by limiting the mass fraction of the blackening filler, the shape-memory phenolic composite material that can be ceramicized in space can have an absorptivity of ≥95% in the near-infrared band and can reach the ceramicization temperature through laser heating. In this way, by controlling the amount of blackening filler, a breakthrough is achieved in the control of light-to-heat conversion efficiency and ceramicization uniformity in a space environment.

[0059] It should be noted that in order to avoid uneven mixing of the blackening filler due to excessively large particle size, the particle size of the blackening filler is limited to ≤10μm (for example, it can be 10μm, 8μm, 6μm, 5μm, 4μm, 3μm, 2μm, etc.).

[0060] According to some preferred embodiments, in step S1, the mass fraction of the shape memory phenolic resin prepolymer in the mixture is 40% to 80% (for example, 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78% or 80%);

[0061] The mass fraction of the ceramic powder in the mixture is 18-58% (for example, it can be 18%, 20%, 22%, 24%, 25%, 26%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, 52%, 55% or 58%).

[0062] According to some more preferred embodiments, the sum of the mass fractions of the black filler and the ceramic powder in the mixture is 20-60%. If the sum of the mass fractions is lower than 20%, it will affect the ceramic yield of the shape-memory phenolic composite material that can be ceramicized in the air. However, if the sum of the mass fractions is higher than 60%, it will affect the deformation ability of the shape-memory phenolic composite material that can be ceramicized in the air.

[0063] According to some preferred embodiments, in step S1, the mixing is melt stirring or crushing and grinding.

[0064] It should be noted that the shape memory phenolic resin prepolymer is solid at room temperature (e.g., 25°C). Specifically, the particle size of the mixture obtained after crushing and grinding is 10 nm to 100 μm. Specifically, because the melting point of the shape memory phenolic resin prepolymer is relatively low, the shape memory phenolic resin prepolymer needs to be cooled to below 0°C before step S1 to make it easier to crush and grind, so that the several materials are easier to mix and the mixing effect is better.

[0065] According to some preferred embodiments, in step S2, the heating temperature is 80-100° C. (for example, 80° C., 81° C., 82° C., 83° C., 84° C., 85° C., 86° C., 87° C., 88° C., 89° C., 90° C., 91° C., 92° C., 93° C., 94° C., 95° C., 96° C., 97° C., 98° C., 99° C., or 100° C.), and the heating time is 2-4 h (for example, 2 h, 2.5 h, 3 h, 3.5 h, or 4 h);

[0066] The curing adopts step curing.

[0067] In an embodiment of the present invention, a shape-memory phenolic resin prepolymer is grown in situ on the filler surface by controlling the heating temperature. The formation of a phenolic resin cross-linked network is fundamental to the composite material's excellent performance. However, since phenolic resin produces small water molecules during the curing process, this can generate bubbles. The present invention minimizes bubble generation through a slow, step-wise curing process, thereby improving the composite material's performance.

[0068] Specifically, the step curing process includes but is not limited to: keeping warm at 100°C for 2 hours, keeping warm at 105°C for 2 hours, keeping warm at 110°C for 4 hours, keeping warm at 115°C for 4 hours, and keeping warm at 120°C for 4 hours; or keeping warm at 100°C for 2 hours, keeping warm at 105°C for 4 hours, keeping warm at 110°C for 2 hours, keeping warm at 115°C for 4 hours, and keeping warm at 120°C for 4 hours; or keeping warm at 100°C for 2 hours, keeping warm at 105°C for 2 hours, keeping warm at 110°C for 2 hours, keeping warm at 115°C for 5 hours, and keeping warm at 120°C for 5 hours; or keeping warm at 100°C for 2 hours, keeping warm at 105°C for 2 hours, keeping warm at 110°C for 2 hours, keeping warm at 115°C for 4 hours, and keeping warm at 120°C for 6 hours.

[0069] The present invention also provides a shape memory phenolic composite material capable of being ceramicized in space, and the glass transition temperature thereof is 100-150°C.

[0070] The present invention also provides an application of a shape memory phenolic composite material capable of being ceramicized in space, comprising:

[0071] The shape-memory phenolic composite material that can be ceramicized in space is heated on the ground to above the glass transition temperature, and is shaped so that the shape-memory phenolic composite material that can be ceramicized in space has a temporary shape; the shape-memory phenolic composite material that can be ceramicized in space with the temporary shape is heated in the air to obtain the shape-memory phenolic composite material that can be ceramicized in space with an initial shape; wherein the volume of the temporary shape is smaller than the volume of the initial shape; and the shape-memory phenolic composite material that can be ceramicized in space with the initial shape is ceramicized in the air to obtain a ceramicized phenolic composite material.

[0072] According to some preferred embodiments, the shape-memory phenolic composite material that can be ceramicized in air and has a temporary shape is heated in air to obtain the shape-memory phenolic composite material that can be ceramicized in air and has an initial shape, including: heating by using an electric heating film or laser heating.

[0073] According to some preferred embodiments, a power density of 50 to 200 W / cm is used. 2 (For example, it can be 50W / cm 2 、60W / cm 2 , 70W / cm 2 、80W / cm 2 , 90W / cm2 , 100W / cm 2 、110W / cm 2 , 120W / cm 2 、130W / cm 2 、140W / cm 2 , 150W / cm 2 、160W / cm 2 、170W / cm 2 、180W / cm 2 、190W / cm 2 or 200W / cm 2 ) laser irradiation of the shape memory phenolic composite material with the initial shape that can be ceramicized in the air is completed by ceramicization.

[0074] According to some more preferred embodiments, the laser spot diameter is 0.5 to 5 mm (for example, it can be 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm or 5 mm), and the scanning speed is 1 to 10 mm / s (for example, it can be 1 mm / s, 2 mm / s, 3 mm / s, 4 mm / s, 5 mm / s, 6 mm / s, 7 mm / s, 8 mm / s, 9 mm / s or 10 mm / s).

[0075] Specifically, the application of aerospace-ceramic shape-memory phenolic composite material involves three stages: I. Ground shaping stage: heating the aerospace-ceramic shape-memory phenolic composite material in a high-temperature oven to form it into a temporary shape; II. Spatial expansion stage: restoring the temporary shape to its initial shape using an electric heating film or laser heating; and III. Spatial ceramicization stage: ceramicizing the aerospace-ceramic shape-memory phenolic composite material at high temperature using spatial laser scanning. It should be noted that the aerospace-ceramic shape-memory phenolic composite material exhibits shape memory properties in stages I and II.

[0076] Specifically, in stage I, the heating temperature can be 120-170°C (for example, 120°C, 130°C, 140°C, 150°C, 160°C or 170°C), specifically according to the glass transition temperature of the aerospace-ceramic shape memory phenolic composite material, and the temperature is kept for 5-20 minutes. At this time, the modulus of the aerospace-ceramic shape memory phenolic composite material in this state is lower than 100Mpa, which is conducive to shaping the composite material. In stage II, the composite material is heated to 150-200°C (for example, 150°C, 160°C, 170°C, 180°C, 190°C or 200°C) by using an electric heating film or laser heating method, and the higher the heating temperature, the faster the composite material recovers. In stage III, the greater the laser power, the faster the material heats.

[0077] According to some more preferred embodiments, the space-ceramicable shape memory phenolic composite material needs to be heated to 1600° C. during the laser ceramicizing process in the space ceramicizing stage.

[0078] Because the voltage of equipment power supplies permitted in space does not exceed 28V, heating using only this power supply can only reach around 100°C, which is insufficient for the high-temperature sintering required for ceramicization. This invention, by introducing a blackening filler and employing laser ceramicization, utilizes existing equipment power supplies to emit lasers. This not only enables the space-ceramic shape-memory phenolic composite material to reach the required ceramicization temperature, but also eliminates the need for a high-voltage power supply and does not increase the weight of the space station or the launch vehicle.

[0079] In order to more clearly illustrate the technical solutions and advantages of the present invention, a shape-memory phenolic composite material capable of being ceramicized in space, and its preparation method and application are described in detail through the following examples.

[0080] The shape memory phenolic resin prepolymers in the following examples and comparative examples were obtained by the following method:

[0081] Example 1

[0082] S0, placing ZrO2 powder (particle size ≤ 10 μm) in concentrated oxalic acid, heating to 80°C in an oil bath, and stirring for 4 hours for carboxylation pretreatment to obtain carboxyl-modified ZrO2 powder to enhance the interfacial bonding between the ceramic powder and the high-temperature resistant shape memory boron phenolic resin prepolymer, and drying the carboxylated ZrO2 powder under vacuum at 120°C for 6 hours;

[0083] S1. Place the shape memory boron phenolic resin prepolymer in a sealed bag and refrigerate it in a freezer for 20 minutes to ensure that the temperature of the shape memory boron phenolic resin prepolymer is below 0° C.; Place the shape memory boron phenolic resin prepolymer, carboxylated ZrO2 powder, and carbon nanotubes in a high-speed grinder in a mass ratio of 70%:28%:2% to obtain a mixture (particle size less than 100 μm);

[0084] S2. The mixture is heated to 90°C to allow the shape-memory boron phenolic resin prepolymer to grow in situ on the surface of the carboxylated ZrO2 powder for 3 hours, thereby obtaining an initial composite material. The initial composite material is then placed in a mold for hot-pressing and curing, and the water generated during the curing process is expelled as quickly as possible to prevent the formation of bubbles in the composite material. The mold is then placed in a vacuum chamber for heat curing and demolding to obtain a shape-memory phenolic composite material capable of aerospace laser ceramicization. The curing is performed using a step-by-step heating process: 100°C for 2 hours, 105°C for 2 hours, 110°C for 4 hours, 115°C for 4 hours, and finally 120°C for 4 hours.

[0085] application:

[0086] (1) placing the shape memory phenolic composite material capable of being laser-ceramicized in an oven at 150° C. for 20 minutes, and shaping the composite material into a U-shaped part after the stiffness of the composite material is reduced;

[0087] (2) Use a laser transmitter to scan the material. To meet aerospace requirements, the laser voltage is selected as 25V (lower than the limit of 28V) and the laser power density is 100W / cm 2 , the spot diameter is 1mm, the scanning speed is 1mm / s, the composite material of the U-shaped part can complete the shape recovery within 30s, and the ceramicization process can be completed within 10min by continuing the laser scanning. Figure 2 shown.

[0088] XPS analysis of the ceramicized composite material of Example 1 revealed that a large number of Zr-C bonds were generated in the ceramicized composite material, realizing the transformation of ZrO2 into the ceramic component ZrC, proving that the shape memory phenolic composite material capable of aerospace laser ceramicization has the ability of laser ceramicization.

[0089] Experiments have confirmed that the shape-memory phenolic composite material capable of aerospace laser ceramicization in Example 1 has a shape fixation rate of 98% and a shape recovery rate of 99%, both of which are at a high level, proving that it has excellent shape memory properties; at the same time, the residual carbon rate measured under nitrogen conditions at 1000°C is 70%, proving that it has excellent high-temperature stability and has outstanding application value in aerospace and other fields.

[0090] Example 2

[0091] S0, placing TiO2 powder (particle size ≤ 10 μm) in concentrated oxalic acid, heating to 80°C in an oil bath, and stirring for 4 hours for carboxylation pretreatment to obtain carboxyl-modified TiO2 powder to enhance the interfacial bonding between the ceramic powder and the high-temperature resistant shape memory boron phenolic resin prepolymer, and drying the carboxylated TiO2 powder under vacuum at 120°C for 6 hours;

[0092] S1. Place the shape memory boron phenolic resin prepolymer in a sealed bag and refrigerate it in a freezer for 20 minutes to ensure that the temperature of the shape memory boron phenolic resin prepolymer is below 0° C.; Place the shape memory boron phenolic resin prepolymer, carboxylated TiO2 powder, and carbon nanotubes in a high-speed grinder in a mass ratio of 74%:24%:2% to obtain a mixture (particle size less than 100 μm);

[0093] S2. The mixture is heated to 90°C to allow the shape-memory boron phenolic resin prepolymer to grow in situ on the surface of the carboxylated TiO2 powder for 4 hours to obtain an initial composite material. The initial composite material is placed in a mold for hot pressing and curing, and the water generated during the curing process is expelled as quickly as possible to prevent the formation of bubbles in the composite material. The mold is then placed in a vacuum chamber for heat curing and demolding to obtain a shape-memory phenolic composite material that can be aerospace laser ceramicized. The heating and curing adopts a step-by-step temperature curing method, specifically: 100°C for 2 hours, 105°C for 2 hours, 110°C for 2 hours, 115°C for 4 hours, and 120°C for 6 hours.

[0094] application:

[0095] (1) placing the shape memory phenolic composite material capable of being laser-ceramicized in an oven at 170° C. for 10 minutes, and shaping the composite material after its stiffness is reduced, and the composite material can be shaped into a temporary shape;

[0096] (2) The material is scanned using a laser transmitter. To meet aerospace requirements, the laser voltage is selected as 25V (lower than the 28V limit) and the laser power density is 60W / cm 2 , the spot diameter is 5mm, the scanning speed is 5mm / s, the composite material with a temporary shape can complete shape recovery within 30s, and continued laser scanning can complete the ceramic process within 10min.

[0097] Experiments have confirmed that the shape-memory phenolic composite material capable of aerospace laser ceramicization in Example 2 has a shape fixation rate of 97% and a shape recovery rate of 98%, both of which are at a relatively high level, proving that it has excellent shape memory properties; at the same time, the residual carbon rate measured under nitrogen conditions at 1000°C is 65%, proving that it has excellent high-temperature stability and has outstanding application value in aerospace and other fields.

[0098] Example 3

[0099] Example 3 is basically the same as Example 1, except that the mass ratio of the shape memory boron phenolic resin prepolymer, the carboxylated ZrO2 powder, and the carbon nanotubes is 40%:58%:2%.

[0100] Example 4

[0101] Example 4 is substantially the same as Example 1, except that the mass ratio of the shape memory boron phenolic resin prepolymer, the carboxylated ZrO2 powder, and the carbon nanotubes is 49.5%:49%:1.5%.

[0102] Example 5

[0103] Example 5 is substantially the same as Example 1, except that the mass ratio of the shape memory boron phenolic resin prepolymer, the carboxylated ZrO2 powder, and the carbon nanotubes is 60%:38%:2%.

[0104] Comparative Example 1

[0105] Comparative Example 1 is substantially the same as Example 1, except that the mass ratio of the shape memory boron phenolic resin prepolymer, the carboxylated ZrO2 powder, and the carbon nanotubes is 30%:68%:2%.

[0106] Comparative Example 2

[0107] Comparative Example 2 is substantially the same as Example 1, except that the mass ratio of the shape memory boron phenolic resin prepolymer, the carboxylated ZrO2 powder, and the carbon nanotubes is 90%:8%:2%.

[0108] Comparative Example 3

[0109] Comparative Example 3 is substantially the same as Example 1, except that the mass ratio of the shape memory boron phenolic resin prepolymer, the carboxylated ZrO2 powder, and the carbon nanotubes is 70%:29%:1%.

[0110] Comparative Example 4

[0111] Comparative Example 4 is substantially the same as Example 1, except that the mass ratio of the shape memory boron phenolic resin prepolymer, the carboxylated ZrO2 powder, and the carbon nanotubes is 69%:28%:3%.

[0112] Comparative Example 5

[0113] Comparative Example 5 is substantially the same as Example 1, except that no carboxylation pretreatment is performed. Specifically, in step S1, a shape memory boron phenolic resin prepolymer, ZrO2 powder, and carbon nanotubes are mixed in a high-speed grinder at a mass ratio of 70%:28%:2% to obtain a mixture (particle size less than 100 μm).

[0114] The space-ceramicizable shape-memory phenolic composite materials prepared in Examples 1 to 5 of the present invention all have shape memory functions and can be ceramicized by laser scanning.

[0115] like Figure 2 It can be seen that the initial shape of the phenolic composite material that can be aerospace-ceramicized in Example 1 is an arc shape. It can be shaped by heating it to above the shape transition temperature, and the temporary shape shaped into a U shape. The composite material in the temporary shape can be heated to the shape transition temperature again under the action of laser and then return to the original shape in a short time. It has excellent shape memory performance. The laser can continuously heat the composite material to ceramicize it to produce ceramics.

[0116] Depend on Figures 3 to 4 It can be seen that the phenolic composite material that can be aerospace-ceramicized in Example 1 has a glass transition temperature of 118°C. At this temperature, the storage modulus of the composite material is lower than 70 MPa, and it can be easily deformed. The shape transition temperature of the composite material is 118°C, which is a medium-temperature shape memory polymer material with simple shaping conditions and easy shaping. It has a wide application space and can be applied to the aerospace field.

[0117] Depend on Figures 5 to 6 It can be seen that the phenolic composite material that can be aerospace-ceramicized in Example 2 has a glass transition temperature of 130°C. At this temperature, the storage modulus of the composite material is lower than 70 MPa, and it can be easily deformed. The shape transition temperature of the composite material is 130°C, which is a medium-temperature shape memory polymer material with simple shaping conditions and easy shaping. It has a wide application space and can be used in the aerospace field.

[0118] Depend on Figure 7 It can be seen that the characteristic peaks of the ceramic component ZrC in the infrared curve of the shape memory phenolic composite material capable of being space-ceramicized in Example 1 after laser ceramicization are obvious, specifically as follows: appearing at 600–800 cm -1 The stretching vibration peak of the Zr-C bond in the region can confirm that ZrC is generated after laser ceramicization, that is, the ceramicization is successful. Figure 8 It can be seen that the characteristic peak of the ceramic component ZrC in the XPS of the shape memory phenolic composite material that can be space-ceramified in Example 1 after laser ceramicization is obvious, as follows: Zr-C at a bond energy of 182.5 eV can be separated from the XPS curve, proving that ZrC is generated during the laser ceramicization process, that is, the ceramicization is successful. Figure 9 It can be seen that the shape memory phenolic composite material capable of aerospace ceramicization provided in Example 1 has a carbon residue rate of 70% measured under nitrogen at 1000°C, and the composite material provided in Example 2 has a carbon residue rate of 65% measured under nitrogen at 1000°C, and the temperature at which the mass decay is 5% is higher than 350°C. Both are high-temperature resin-based composite materials and have application potential in extreme thermal environments in the aerospace field.

[0119] In Comparative Example 1, due to too much ceramic powder, the continuity of the shape memory boron phenolic resin prepolymer during curing is affected. When the material is deformed after curing, it is restricted by the inorganic filler. After heating, the storage modulus of the material does not decrease, the rigidity does not change, the material does not soften, and it is impossible to perform shaping, i.e., it does not have shape memory properties. In Comparative Example 2, too much shape memory boron phenolic resin prepolymer is added, and the amount of ceramic powder added is too little. The prepared composite material still has shape memory properties, but it is difficult to achieve ceramicization. In Comparative Example 3, due to too little black filler added, the prepared composite material does not appear black after curing, resulting in a decrease in the light-to-heat conversion efficiency of the composite material. The material cannot absorb light energy and convert it into heat energy, making it difficult to heat the material. The material cannot undergo laser recovery and laser ceramicization processes, but the material can still complete the ceramicization process in a vacuum tube furnace, i.e., it does not have aerospace ceramicization properties. The excessive addition of carbon nanotubes in Comparative Example 4 compromises the continuity of the shape-memory boron phenolic resin prepolymer during curing. The material's deformation after curing is limited by the inorganic filler, resulting in no decrease in storage modulus or change in stiffness after heating. The material also fails to soften and cannot be shaped, meaning it lacks shape memory properties. In Comparative Example 5, because the ceramic powder was not pretreated with carboxylation, only a physical interface forms between the ceramic powder and the shape-memory boron phenolic resin prepolymer, reducing interfacial strength and potentially damaging the composite material during the post-curing shaping process.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a shape memory phenolic composite material capable of being ceramicized in space, characterized in that: The preparation method comprises the following steps: S1, mixing a shape memory phenolic resin prepolymer with ceramic powder and a blackening filler to obtain a mixture; S2. The mixture is heated and cured in sequence to obtain a shape memory phenolic composite material capable of being aerospace-ceramicized.

2. The preparation method according to claim 1, characterized in that In step S1, the shape memory phenolic resin prepolymer includes a shape memory boron phenolic resin prepolymer, a shape memory boron phenolic resin derivative prepolymer, a shape memory silicon phenolic resin prepolymer or a shape memory silicon phenolic resin derivative prepolymer; and / or The glass transition temperature of the aerospace-ceramicizable shape-memory phenolic composite material is 100-150°C.

3. The preparation method according to claim 1, characterized in that In step S1, the ceramic powder is one or more of SiO2, Al2O3, ZrO2, and HfO2; and / or The particle size of the ceramic powder is ≤10 μm.

4. The preparation method according to claim 1, characterized in that In step S1, the blackening filler is at least one of carbon black and carbon nanotubes; preferably, the absorptivity of the aerospace-ceramic shape-memory phenolic composite material in the near-infrared band is ≥95%.

5. The preparation method according to claim 1, characterized in that In step S1, the mass fraction of the shape memory phenolic resin prepolymer in the mixture is 40-80%; The mass fraction of the ceramic powder in the mixture is 18 to 58%; and / or, The mass fraction of the blackening filler is 1.5-2%.

6. The preparation method according to claim 5, characterized in that In step S1, the mixing is melt stirring or crushing and grinding; and / or In step S2, the heating temperature is 80-100° C. and the heating time is 2-4 hours; The curing adopts step curing. 7 . The preparation method according to claim 1 , further comprising, before step S1 , performing a carboxylation pretreatment on the ceramic powder so that the surface of the ceramic powder contains carboxyl functional groups.

8. A shape memory phenolic composite material capable of being ceramicized in space, characterized in that: The preparation method according to any one of claims 1 to 7 is used.

9. Application of the shape memory phenolic composite material capable of being ceramicized in space by the preparation method according to any one of claims 1 to 7, characterized in that: The shape-memory phenolic composite material that can be ceramicized in space is heated on the ground to above the glass transition temperature, and is shaped so that the shape-memory phenolic composite material that can be ceramicized in space has a temporary shape; the shape-memory phenolic composite material that can be ceramicized in space with the temporary shape is heated in the air to obtain a shape-memory phenolic composite material that can be ceramicized in space with an initial shape; wherein the volume of the temporary shape is smaller than the volume of the initial shape; and the shape-memory phenolic composite material that can be ceramicized in space with the initial shape is ceramicized in the air to obtain a ceramicized phenolic composite material.

10. The use according to claim 9, characterized in that The method of heating the shape-memory phenolic composite material capable of being ceramicized in space and having a temporary shape in space in the air to obtain the shape-memory phenolic composite material capable of being ceramicized in space and having an initial shape comprises: heating by means of an electric heating film or laser heating; and / or Use power density 50~200W / cm 2 The shape memory phenolic composite material that can be ceramicized in the air is irradiated with a laser to complete ceramicization. Preferably, the laser spot diameter is 0.5 to 5 mm, and the scanning speed is 1 to 10 mm / s.

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