Integrated floor ceiling and manufacturing method thereof

Abstract

The present application relates to the field, specifically discloses a kind of integrated ceiling cornice in floor and its manufacturing method, wherein manufacturing method includes: S1, the biobased epoxy resin prepolymer, polyurethane modifier, active diluent and curing accelerator are mixed, and the liquid matrix material A is prepared;S2, piezoelectric ceramic particles, magnetic magnetite nano particles, repair microcapsule, carbon nanotube and dispersing agent are added in A, and composite slurry B is obtained by ultrasonic dispersion;S3, B is injected into mould, is placed in magnetic field parallel to the length direction of cornice, so that filler directional arrangement is formed preform C;S4, C is first ultraviolet light curing surface layer, then stepwise heat curing is carried out, and cornice blank D is obtained;S5, aluminum film electrode is prepared on the surface of D and coated with encapsulation glue, and ceiling cornice is prepared.The ceiling cornice prepared by the present application has micro-damage self-repairing ability and the ability to convert environmental vibration energy into electrical energy, and realizes the leap from passive bearing to active intelligence.

Description

Technical Field

[0001] This invention relates to the field of prefabricated integrated floor slabs, and in particular to an integrated floor slab with an internal ceiling keel and its manufacturing method. Background Technology

[0002] Traditional ceiling joists, whether made of metal, wood, or composite materials, primarily function as mechanical supports, bearing the weight of ceiling panels and their accessories. With the increasing prevalence of green and intelligent building concepts, higher demands are being placed on the functionality of building components, expecting them not only to meet basic structural safety requirements but also to contribute to energy conservation, durability, and intelligent features. However, existing ceiling joists have significant shortcomings: First, as components subjected to long-term static and dynamic loads, they are prone to developing micro-cracks due to stress concentration and fatigue. These damages are difficult to detect and repair, accumulating gradually and affecting long-term load-bearing safety. Traditional methods only allow for complete replacement after failure, resulting in high maintenance costs and poor sustainability. Second, the joist is entirely an energy-consuming unit; it and the systems it supports (such as lighting fixtures) require continuous power, while a large amount of collectable, low-level mechanical energy from vibrations in the building environment (such as human movement and equipment operation) is wasted. Currently, no technological solution has been found that can integrate self-healing capabilities and energy harvesting functions into the basic component of a building keel, thereby simultaneously solving the challenges of its long-term safety and enabling the building's microsystems to supply energy. Therefore, developing a ceiling keel with self-sensing, self-healing capabilities and the ability to harvest environmental energy is of great significance. Summary of the Invention

[0003] To address the problems existing in the prior art and realize the self-sensing and self-repairing functions of the ceiling joists, this invention provides an integrated floor slab ceiling joist and its manufacturing method.

[0004] The technical solution adopted in this invention is:

[0005] A method for manufacturing integrated floor slab internal ceiling joists includes the following steps:

[0006] S1. Mix and stir 50-70 parts by weight of bio-based epoxy resin prepolymer, 20-30 parts by weight of polyurethane modifier, 5-10 parts by weight of reactive diluent and 1-3 parts by weight of curing accelerator at 60-80℃ for 20-40 minutes to obtain liquid matrix material A.

[0007] S2. Add 2-5 parts by weight of piezoelectric ceramic particles, 1-3 parts by weight of magnetic iron oxide nanoparticles, 3-8 parts by weight of repair microcapsules, 0.5-2 parts by weight of carbon nanotubes and 0.1-0.5 parts by weight of dispersant to the liquid matrix material A obtained in step S1, transfer it to an ultrasonic dispersion device, and ultrasonically disperse it for 30-60 minutes under the conditions of ultrasonic power of 500-800W and temperature of 40-60℃ to obtain a uniformly dispersed composite slurry B.

[0008] S3. Inject the composite slurry B into the cavity of the keel forming mold, place the mold in a uniform steady magnetic field with an intensity of 0.3-0.8T, with the magnetic field direction parallel to the length direction of the keel, and let it stand for 5-15 minutes to allow the magnetic iron oxide nanoparticles to align along the magnetic field direction, which in turn drives the piezoelectric ceramic particles and carbon nanotubes to oriented and form a preform C.

[0009] S4. Place the preform C together with the mold under ultraviolet light with a wavelength of 365nm for 10-20 minutes to perform surface photocuring; then perform step-by-step thermal curing: keep at 60℃ for 1 hour, then raise the temperature to 80℃ and keep at 80℃ for 2 hours, and finally raise the temperature to 100℃ and keep at 1 hour to obtain the fully cured keel blank D.

[0010] S5. On the two opposite sides of the keel blank D, a layer of aluminum film with a thickness of 50-200nm is deposited as an electrode by magnetron sputtering; then, a transparent insulating encapsulating adhesive is coated on the electrode surface and cured at 80℃ for 30 minutes to form a protective layer, thus obtaining the ceiling keel.

[0011] Preferably, in step S1, the bio-based epoxy resin prepolymer is cashew phenol glycidyl ether or soybean oil-based epoxy resin with an epoxy value of 0.4-0.6 eq / 100g; the polyurethane modifier is a hydroxyl-terminated polyurethane prepolymer with a molecular weight of 2000-5000 g / mol; the reactive diluent is 1,4-butanediol diglycidyl ether; and the curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

[0012] Preferably, in step S2, the piezoelectric ceramic particles are lead zirconate titanate or potassium sodium niobate with a particle size of 1-10 μm; the magnetic iron oxide nanoparticles have a particle size of 20-100 nm; the carbon nanotubes are multi-walled carbon nanotubes with a length of 5-20 μm and a diameter of 10-20 nm; and the dispersant is a polyoxyethylene type nonionic surfactant.

[0013] Preferably, in step S2, the core of the repair microcapsule is an uncured bio-based epoxy resin prepolymer, and the capsule wall is urea-formaldehyde resin.

[0014] The preparation method of the repair microcapsules is as follows:

[0015] The microcapsules were prepared by in-situ polymerization, using a mixture of bio-based epoxy resin prepolymer and curing accelerator as the core material and a prepolymer of urea and formaldehyde as the wall material. The reaction was carried out at 50-70℃ for 2-4 hours under the action of emulsifier and acid catalyst. The average particle size of the microcapsules was 50-200μm and the wall thickness was 2-10μm.

[0016] Preferably, in step S3, the uniform steady-state magnetic field is generated by passing a direct current through a pair of parallel Helmholtz coils, and the magnetic field strength is... The magnitude is determined by the current flowing through the coil. Control, and their relationship satisfies the formula ,in, The number of turns in a single coil. Let be the radius of the MUHOZ coil.

[0017] Preferably, in step S4, the stepped thermosetting process follows a curing kinetic model to achieve a certain degree of curing. With time ,temperature The relationship satisfies the modified Kamal equation to achieve internal stress minimization and complete curing.

[0018] Preferably, in step S5, the process parameters for magnetron sputtering aluminum film deposition are: a base vacuum degree not exceeding 5.0 × 10⁻⁶. − 3 The sputtering working pressure is 0.5-1.0a, the argon flow rate is 20-40sccm, the sputtering power is 100-200W, and the sputtering time is 10-30 minutes.

[0019] Preferably, after step S5, step S6 is further included:

[0020] The frequency of the prepared ceiling keel sample was applied to it. Peak value is A sinusoidal alternating load was subjected to a test to measure its open-circuit output voltage. and according to the formula Calculate its effective piezoelectric constant To quantitatively calibrate its energy harvesting performance, among which, The relative permittivity of the ceiling keel sample is given. The vacuum permittivity, This refers to the effective area of ​​the conductive electrode plate that participates in charge collection and is actually connected to the external measurement circuit in the aluminum film electrode deposited on the surface of the keel blank D by magnetron sputtering. The thickness of the ceiling keel sample between the two electrodes.

[0021] An integrated floor slab ceiling joist is manufactured by any of the above-described manufacturing methods.

[0022] The beneficial effects of this invention are:

[0023] 1. By pre-dispersing repair microcapsules containing uncured resin in the keel matrix, when microcracks are generated due to stress during use, the stress concentration at the crack tip causes the microcapsule wall to rupture. The released repair agent is injected into the crack under capillary action and polymerizes upon contact with the residual curing agent in the matrix, thereby re-bonding the crack. This can automatically repair early and hidden damage, prevent crack propagation, and transform material failure from catastrophic failure to self-repairing local damage, greatly improving the reliability and durability of components and reducing maintenance requirements.

[0024] 2. By introducing oriented piezoelectric ceramic particles, the keel can directly convert the random vibration mechanical energy (such as floor vibration) that is common in the environment into electrical energy. When the keel is bent and deformed by force, the oriented piezoelectric crystals inside will generate charge separation, forming a potential difference on the surface electrode, thereby outputting an electrical signal. The collected electrical energy can power low-power sensors (such as temperature, humidity, light, and smoke sensors) or miniature LED indicator lights integrated in the ceiling, promoting the construction of self-powered intelligent building microsystems that do not require external power or can significantly extend battery life, which is in line with the development trend of green and energy-saving buildings.

[0025] 3. By utilizing the directional alignment of magnetic nanoparticles in a magnetic field, piezoelectric particles and carbon nanotubes are driven to form an ordered structure along the main force direction (length direction) of the keel. In the length direction, the force-electric coupling efficiency of the piezoelectric filler is maximized, improving energy harvesting efficiency. At the same time, the ordered arrangement of reinforcing phases (such as carbon nanotubes) and filler chains can more effectively hinder crack propagation in the vertical direction, enhancing fracture toughness in this direction. This design enables the material to achieve directional improvement of key properties with limited dosage, which is unattainable by traditional randomly dispersed composite materials. Detailed Implementation

[0026] The following embodiments provide a detailed description of the present invention.

[0027] Example 1

[0028] A method for manufacturing integrated floor slab internal ceiling joists includes the following steps:

[0029] S1. Mix 50 parts by weight of bio-based epoxy resin prepolymer, 20 parts by weight of polyurethane modifier, 5 parts by weight of reactive diluent and 1 part by weight of curing accelerator at 60°C for 20 minutes to obtain liquid matrix material A.

[0030] S2. Add 2 parts by weight of piezoelectric ceramic particles, 1 part of magnetic iron oxide nanoparticles, 3 parts of repair microcapsules, 0.5 parts of carbon nanotubes and 0.1 parts of dispersant to the liquid matrix material A obtained in step S1, transfer to an ultrasonic dispersion device, and ultrasonically disperse for 30 minutes under the conditions of ultrasonic power of 500W and temperature of 40℃ to obtain a uniformly dispersed composite slurry B.

[0031] S3. Inject the composite slurry B into the cavity of the keel forming mold, place the mold in a uniform steady magnetic field with an intensity of 0.3T, with the magnetic field direction parallel to the keel length direction, and let it stand for 5 minutes to allow the magnetic iron oxide nanoparticles to align along the magnetic field direction, which in turn drives the piezoelectric ceramic particles and carbon nanotubes to oriented and form a preform C.

[0032] S4. Place the preform C together with the mold under ultraviolet light with a wavelength of 365nm for 10 minutes to perform surface photocuring; then perform step-by-step thermocuring: keep at 60℃ for 1 hour, then raise the temperature to 80℃ and keep at 80℃ for 2 hours, and finally raise the temperature to 100℃ and keep at 1 hour to obtain the fully cured keel blank D.

[0033] S5. On the two opposite sides of the keel blank D, a layer of aluminum film with a thickness of 50nm is deposited as an electrode by magnetron sputtering; then, a transparent insulating encapsulating adhesive is coated on the electrode surface and cured at 80℃ for 30 minutes to form a protective layer, thus obtaining the ceiling keel.

[0034] Traditional ceiling joists have a single function and lack the ability to self-repair internal micro-damage during long-term use, nor can they convert the mechanical energy of vibration in the building environment into usable electrical energy.

[0035] This method addresses the above problems by creating a novel composite material. Specifically, in steps S1 and S2, a flexible, curable resin matrix is ​​combined with various functional fillers. Piezoelectric ceramic particles convert mechanical vibrations into electrical signals, while magnetic iron oxide nanoparticles act as magnetic guides. When microcracks appear in the material, the capsules rupture, releasing a repair agent to automatically repair the damage. In step S3, a magnetic field is used to orient the fillers, significantly improving the piezoelectric output efficiency and crack propagation resistance along the length of the filler. In step S4, a process of first photocuring and then thermal gradient deep curing ensures uniform curing both inside and outside the material without damaging the functional fillers. Finally, in step S5, the piezoelectric charges generated internally are discharged, forming collectable electrical energy.

[0036] The ceiling joists produced by this method break through the limitations of traditional joists, which are merely passive load-bearing components, and endow them with active attributes such as sensing, response, self-maintenance, and power supply.

[0037] 1. Self-healing function: Microcapsules can automatically repair micro-damage to materials, significantly extending the service life of the keel under complex stress and reducing maintenance costs.

[0038] 2. Energy harvesting function: Through the piezoelectric effect, the wasteful vibration mechanical energy that is common in buildings is converted into electrical energy, which can power low-power building sensors and help build self-powered IoT smart buildings.

[0039] 3. Anisotropic performance design: The directional arrangement of functional fillers is achieved through magnetic field induction, which specifically enhances the piezoelectric sensitivity, crack resistance and stiffness of the keel along its length, realizing the customization of material performance as needed.

[0040] To ensure the matrix possesses good flexibility, compatibility with functional fillers, and controllable curing characteristics, in step S1, the bio-based epoxy resin prepolymer is cashew phenol glycidyl ether or soybean oil-based epoxy resin with an epoxy value of 0.4 eq / 100g; the polyurethane modifier is a hydroxyl-terminated polyurethane prepolymer with a molecular weight of 2000 g / mol; the reactive diluent is 1,4-butanediol diglycidyl ether; and the curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

[0041] Bio-based epoxy resin provides an environmentally friendly, curable network framework; polyurethane segments are introduced as flexible segments to improve the toughness of the cured material; reactive diluents adjust the system viscosity; and curing accelerators effectively reduce the curing temperature, preventing high-temperature damage to functional fillers. The synergistic effect of these components gives the matrix excellent overall performance. The bio-based raw materials are environmentally friendly, and the flexible matrix ensures that stress is effectively transferred to the piezoelectric filler during deformation under load, while also accommodating the flow and re-curing of the repair agent, providing an ideal carrier for realizing intelligent functions.

[0042] Piezoelectric ceramic particles are the core of energy harvesting, while magnetic nanoparticles are the driving units for magnetic field guidance. Carbon nanotubes serve as conductive pathways, connecting the piezoelectric ceramic particles separated by insulating resin to form an effective charge harvesting network. A dispersant is used to prevent filler agglomeration. In step S2, the piezoelectric ceramic particles are lead zirconate titanate or potassium sodium niobate with a particle size of 1 μm; the magnetic iron oxide nanoparticles have a particle size of 20 nm; the carbon nanotubes are multi-walled carbon nanotubes with a length of 5 μm and a diameter of 10 nm; and the dispersant is a polyoxyethylene nonionic surfactant.

[0043] By precisely selecting the parameters of the functional filler, sufficient piezoelectric response, efficient magnetic field response and alignment effect, good electrical conductivity and uniform microstructure of the composite material are ensured.

[0044] Microcapsules are the core of the self-healing function. In step S2, the core of the repair microcapsule is an uncured bio-based epoxy resin prepolymer, and the capsule wall is urea-formaldehyde resin.

[0045] The preparation method of the repair microcapsules is as follows:

[0046] The microcapsules were prepared by in-situ polymerization, using a mixture of bio-based epoxy resin prepolymer and curing accelerator as the core material and a prepolymer of urea and formaldehyde as the wall material. The reaction was carried out at 50°C for 2 hours under the action of emulsifier and acid catalyst. The average particle size of the microcapsules was 50 μm and the wall thickness was 2 μm.

[0047] The core material of the repair microcapsule is homologous to the matrix material, ensuring excellent compatibility and chemical bonding between the repair agent and the matrix. The urea-formaldehyde resin wall material possesses appropriate mechanical strength and brittleness, enabling it to rupture under the stress of microcrack propagation and promptly release the repair agent. The above preparation method and key parameters ensure that the microcapsule exhibits stable storage properties, sensitive response to damage, and excellent repair efficiency, which are prerequisites for achieving reliable and long-lasting self-healing functions.

[0048] To achieve precise and controllable magnetic field, in step S3, a uniform steady-state magnetic field is generated by passing a direct current through a pair of parallel Helmholtz coils, with the magnetic field strength... The magnitude is determined by the current flowing through the coil. Control, and their relationship satisfies the formula ,in, The number of turns in a single coil. Let be the radius of the MUHOZ coil.

[0049] A Helmholtz coil can generate a highly uniform magnetic field in its central region by adjusting the input current. It can linearly and precisely control the magnetic field strength. This ensures the consistency of the packing arrangement in each batch of products, making the key process parameter of magnetic field strength precise, controllable, and repeatable, and enabling precise industrial control of the method.

[0050] Traditional curing processes can easily lead to internal stress and microcracks in materials, thus affecting performance stability. Therefore, in step S4, the stepped thermosetting process follows a curing kinetic model to ensure the degree of curing... With time ,temperature The relationship satisfies the modified Kamal equation to achieve internal stress minimization and complete curing.

[0051] In step S4, the stepped temperature increase program of 60℃-80℃-100℃ is set based on the optimization of the curing kinetics model. This ensures that the degree of curing increases synchronously and uniformly at all points inside the material, avoiding internal stress concentration and defects caused by excessively rapid local reactions. Using a model-based stepped curing program can minimize internal stress, ensure complete curing, protect the interface between the functional filler and the matrix, and maintain the integrity of the microcapsule structure, thereby improving the dimensional stability, durability, and long-term stability of the piezoelectric output of the final keel product.

[0052] To ensure electrode quality and energy harvesting efficiency, in step S5, the process parameters for magnetron sputtering aluminum film deposition are as follows: background vacuum level of 4.8 × 10⁻⁶. −3 The sputtering working pressure is 0.5a, the argon flow rate is 20sccm, the sputtering power is 100-W, and the sputtering time is 10 minutes.

[0053] In magnetron sputtering, controlling the base vacuum and working gas pressure ensures the purity of the coating and the sputtering rate; controlling the power and time precisely controls the film thickness and density. By employing these process parameters, the prepared aluminum electrode can be ensured to possess excellent adhesion, low resistance, and high continuity, guaranteeing stable and efficient energy harvesting.

[0054] To ensure that the product performance meets design requirements, step S6 is included after step S5:

[0055] The frequency of the prepared ceiling keel sample was applied to it. Peak value is A sinusoidal alternating load was subjected to a test to measure its open-circuit output voltage. and according to the formula Calculate its effective piezoelectric constant To quantitatively calibrate its energy harvesting performance, among which, The relative permittivity of the ceiling keel sample is given. The vacuum permittivity, This refers to the effective area of ​​the conductive electrode plate that participates in charge collection and is actually connected to the external measurement circuit in the aluminum film electrode deposited on the surface of the keel blank D by magnetron sputtering. The thickness of the ceiling keel sample between the two electrodes.

[0056] By applying a known dynamic force to the sample and measure the voltage it generates. Combined with the dielectric constant of the material itself Vacuum permittivity and geometric dimensions From this, we can deduce its overall effective piezoelectric constant. This constant comprehensively reflects the energy harvesting capacity of composite materials.

[0057] The above steps provide verification standards for the manufactured ceiling joists, provide objective and quantitative performance testing standards for the finished products, and can provide feedback to guide the optimization of key process parameters.

[0058] Example 2

[0059] A method for manufacturing integrated floor slab internal ceiling joists includes the following steps:

[0060] S1. Mix 60 parts by weight of bio-based epoxy resin prepolymer, 25 parts by weight of polyurethane modifier, 7.5 parts by weight of reactive diluent and 2 parts by weight of curing accelerator at 70°C for 30 minutes to obtain liquid matrix material A.

[0061] S2. Add 3.5 parts by weight of piezoelectric ceramic particles, 2 parts by weight of magnetic iron oxide nanoparticles, 5.5 parts by weight of repair microcapsules, 1.25 parts by weight of carbon nanotubes and 0.3 parts by weight of dispersant to the liquid matrix material A obtained in step S1, transfer it to an ultrasonic dispersion device, and ultrasonically disperse it for 45 minutes under the conditions of ultrasonic power of 650W and temperature of 50℃ to obtain a uniformly dispersed composite slurry B.

[0062] S3. Inject the composite slurry B into the cavity of the keel forming mold, place the mold in a uniform steady magnetic field with a strength of 5.5T, with the magnetic field direction parallel to the length direction of the keel, and let it stand for 10 minutes to allow the magnetic iron oxide nanoparticles to align along the magnetic field direction, which in turn drives the piezoelectric ceramic particles and carbon nanotubes to oriented and form a preform C.

[0063] S4. Place the preform C together with the mold under ultraviolet light with a wavelength of 365nm for 15 minutes to perform surface photocuring; then perform step-by-step thermocuring: keep at 60℃ for 1 hour, then raise the temperature to 80℃ and keep for 2 hours, and finally raise the temperature to 100℃ and keep for 1 hour to obtain the fully cured keel blank D.

[0064] S5. On the two opposite sides of the keel blank D, a layer of aluminum film with a thickness of 125nm is deposited as an electrode by magnetron sputtering; then, a transparent insulating encapsulating adhesive is coated on the electrode surface and cured at 80℃ for 30 minutes to form a protective layer, thus obtaining the ceiling keel.

[0065] In step S1, the bio-based epoxy resin prepolymer is cashew phenol glycidyl ether or soybean oil-based epoxy resin with an epoxy value of 0.5 eq / 100g; the polyurethane modifier is a hydroxyl-terminated polyurethane prepolymer with a molecular weight of 3500 g / mol; the reactive diluent is 1,4-butanediol diglycidyl ether; and the curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

[0066] In step S2, the piezoelectric ceramic particles are lead zirconate titanate or potassium sodium niobate with a particle size of 5.5 μm; the magnetic iron oxide nanoparticles have a particle size of 60 nm; the carbon nanotubes are multi-walled carbon nanotubes with a length of 12.5 μm and a diameter of 15 nm; and the dispersant is a polyoxyethylene type nonionic surfactant.

[0067] In step S2, the core of the repaired microcapsule is an uncured bio-based epoxy resin prepolymer, and the capsule wall is urea-formaldehyde resin.

[0068] The preparation method of the repair microcapsules is as follows:

[0069] The microcapsules were prepared by in-situ polymerization, using a mixture of bio-based epoxy resin prepolymer and curing accelerator as the core material and a prepolymer of urea and formaldehyde as the wall material. The reaction was carried out at 60°C for 3 hours under the action of emulsifier and acid catalyst. The average particle size of the microcapsules was 125 μm and the wall thickness was 6 μm.

[0070] In step S3, a uniform steady-state magnetic field is generated by passing a direct current through a pair of parallel Helmholtz coils, and the magnetic field strength is... The magnitude is determined by the current flowing through the coil. Control, and their relationship satisfies the formula ,in, The number of turns in a single coil. Let be the radius of the MUHOZ coil.

[0071] In step S4, the stepped thermosetting process follows a curing kinetic model, resulting in a certain degree of curing. With time ,temperature The relationship satisfies the modified Kamal equation to achieve internal stress minimization and complete curing.

[0072] In step S5, the process parameters for magnetron sputtering aluminum film deposition are: a base vacuum of 4.9 × 10⁻⁶. −3 The sputtering working pressure is 0.75a, the argon flow rate is 30sccm, the sputtering power is 150W, and the sputtering time is 20 minutes.

[0073] Following step S5, step S6 is also included:

[0074] The frequency of the prepared ceiling keel sample was applied to it. Peak value is A sinusoidal alternating load was subjected to a test to measure its open-circuit output voltage. and according to the formula Calculate its effective piezoelectric constant To quantitatively calibrate its energy harvesting performance, among which, The relative permittivity of the ceiling keel sample is given. The vacuum permittivity, This refers to the effective area of ​​the conductive electrode plate that participates in charge collection and is actually connected to the external measurement circuit in the aluminum film electrode deposited on the surface of the keel blank D by magnetron sputtering. The thickness of the ceiling keel sample between the two electrodes.

[0075] Example 3

[0076] A method for manufacturing integrated floor slab internal ceiling joists includes the following steps:

[0077] S1. Mix 70 parts by weight of bio-based epoxy resin prepolymer, 30 parts by weight of polyurethane modifier, 10 parts by weight of reactive diluent and 3 parts by weight of curing accelerator at 80°C for 40 minutes to obtain liquid matrix material A.

[0078] S2. Add 5 parts by weight of piezoelectric ceramic particles, 3 parts by weight of magnetic iron oxide nanoparticles, 8 parts by weight of repair microcapsules, 2 parts by weight of carbon nanotubes and 0.5 parts by weight of dispersant to the liquid matrix material A obtained in step S1, transfer it to an ultrasonic dispersion device, and ultrasonically disperse it for 60 minutes under the conditions of ultrasonic power of 800W and temperature of 60℃ to obtain a uniformly dispersed composite slurry B.

[0079] S3. Inject the composite slurry B into the cavity of the keel forming mold, place the mold in a uniform steady magnetic field with a strength of 0.8T, with the magnetic field direction parallel to the keel length direction, and let it stand for 15 minutes to allow the magnetic iron oxide nanoparticles to align along the magnetic field direction, which in turn drives the piezoelectric ceramic particles and carbon nanotubes to oriented and form a preform C.

[0080] S4. Place the preform C together with the mold under ultraviolet light with a wavelength of 365nm for 20 minutes to perform surface photocuring; then perform step-by-step thermocuring: keep at 60℃ for 1 hour, then raise the temperature to 80℃ and keep at 80℃ for 2 hours, and finally raise the temperature to 100℃ and keep at 1 hour to obtain the fully cured keel blank D.

[0081] S5. On the two opposite sides of the keel blank D, a layer of aluminum film with a thickness of 200nm is deposited as an electrode by magnetron sputtering; then, a transparent insulating encapsulating adhesive is coated on the electrode surface and cured at 80℃ for 30 minutes to form a protective layer, thus obtaining the ceiling keel.

[0082] In step S1, the bio-based epoxy resin prepolymer is cashew phenol glycidyl ether or soybean oil-based epoxy resin with an epoxy value of 0.6 eq / 100g; the polyurethane modifier is a hydroxyl-terminated polyurethane prepolymer with a molecular weight of 5000 g / mol; the reactive diluent is 1,4-butanediol diglycidyl ether; and the curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

[0083] In step S2, the piezoelectric ceramic particles are lead zirconate titanate or potassium sodium niobate with a particle size of 10 μm; the magnetic iron oxide nanoparticles have a particle size of 100 nm; the carbon nanotubes are multi-walled carbon nanotubes with a length of 20 μm and a diameter of 20 nm; and the dispersant is a polyoxyethylene type nonionic surfactant.

[0084] In step S2, the core of the repaired microcapsule is an uncured bio-based epoxy resin prepolymer, and the capsule wall is urea-formaldehyde resin.

[0085] The preparation method of the repair microcapsules is as follows:

[0086] The microcapsules were prepared by in-situ polymerization, using a mixture of bio-based epoxy resin prepolymer and curing accelerator as the core material and a prepolymer of urea and formaldehyde as the wall material. The reaction was carried out at 70°C for 4 hours under the action of emulsifier and acid catalyst. The average particle size of the microcapsules was 200 μm and the wall thickness was 10 μm.

[0087] In step S3, a uniform steady-state magnetic field is generated by passing a direct current through a pair of parallel Helmholtz coils, and the magnetic field strength is... The magnitude is determined by the current flowing through the coil. Control, and their relationship satisfies the formula ,in, The number of turns in a single coil. Let be the radius of the MUHOZ coil.

[0088] In step S4, the stepped thermosetting process follows a curing kinetic model, resulting in a certain degree of curing. With time ,temperature The relationship satisfies the modified Kamal equation to achieve internal stress minimization and complete curing.

[0089] In step S5, the process parameters for magnetron sputtering aluminum film deposition are: a base vacuum of 5.0 × 10⁻⁶. −3 The sputtering working pressure is 1.0a, the argon flow rate is 40sccm, the sputtering power is 200W, and the sputtering time is 30 minutes.

[0090] Following step S5, step S6 is also included:

[0091] The frequency of the prepared ceiling keel sample was applied to it. Peak value is A sinusoidal alternating load was subjected to a test to measure its open-circuit output voltage. and according to the formula Calculate its effective piezoelectric constant To quantitatively calibrate its energy harvesting performance, among which, The relative permittivity of the ceiling keel sample is given. The vacuum permittivity, This refers to the effective area of ​​the conductive electrode plate that participates in charge collection and is actually connected to the external measurement circuit in the aluminum film electrode deposited on the surface of the keel blank D by magnetron sputtering. The thickness of the ceiling keel sample between the two electrodes.

[0092] Example 4

[0093] This invention provides an integrated floor slab ceiling joist, which is manufactured by the method described in any of the above embodiments.

[0094] Test case

[0095] I. Sample Production:

[0096] Comparative example: Commercially available national standard U50 type galvanized steel keel;

[0097] Experimental Example 1: A keel made using the method described in Example 1;

[0098] Experimental Example 2: Keel made using the method described in Example 2;

[0099] Experimental Example 3: A keel made using the method described in Example 3.

[0100] II. Performance Testing and Result Analysis:

[0101] Test 1: Energy harvesting and self-sensing performance.

[0102] Test method: Each sample (of the same size) is simply supported at both ends, and a peak value is applied at the center point. ,frequency A sinusoidal alternating load was applied to simulate environmental vibrations such as people walking around. The peak open-circuit output voltage of the sample was measured. Calculate the effective piezoelectric constant ,in, , , , Measured by a dielectric spectrometer.

[0103] When the keel is bent and deformed by external force, the internally oriented piezoelectric ceramic particles deform, generating polarization, thus accumulating charge on the surface electrodes and forming a voltage signal. The size directly reflects the keel's ability to convert mechanical energy into electrical energy (energy harvesting), and also reflects its sensitivity to external force strain (self-sensing).

[0104] The test results are shown in Table 1:

[0105] sample Relative permittivity Open circuit output voltage (V) Effective piezoelectric constant (pC / N) Comparative Example - ≈0 0 Experimental Example 1 8.5 0.85 12.6 Experimental Example 2 12.1 2.35 50.4 Experimental Example 3 15.8 4.10 114.9

[0106] Table 1. Open-circuit output voltage and effective piezoelectric constant of each sample

[0107] Data analysis: Traditional keel structures lack piezoelectric output and therefore do not possess energy harvesting and self-sensing capabilities. However, Experiments 1-3 all generated significant voltage signals, confirming that this invention successfully endows the keel structure with energy harvesting and self-sensing capabilities. From Experiments 1-3, with the increase of piezoelectric ceramic content, enhanced magnetic field strength (leading to better alignment), and increased carbon nanotube content (improving charge harvesting efficiency), the results show a clear improvement. and Significant improvement, in Experiment 3 Reaching approximately 115 pC / N demonstrates that optimized parameters can effectively control and significantly improve its core performance.

[0108] Test 2: Self-healing performance evaluation.

[0109] Test method:

[0110] 1. Initial performance: The initial three-point flexural strength of each experimental sample was measured. .

[0111] 2. Introducing damage: Use a blade to pre-cut a V-shaped notch at the bottom of the middle of each sample span, with a depth of 20% of the sample thickness.

[0112] 3. Repair process: The notched sample was placed in a 60℃ oven for 24 hours to simulate the repair process triggered by temperature fluctuations in the building environment.

[0113] 4. Post-repair performance: Measure the three-point flexural strength of the repaired sample. .

[0114] The pre-formed notch creates stress concentration, simulating a microcrack. Under heating conditions, the stress field at the notch tip causes the walls of nearby repair microcapsules to rupture, releasing uncured bio-based epoxy resin prepolymer. This repair agent penetrates the crack through capillary action and comes into contact with the residual curing agent in the matrix, undergoing a polymerization reaction to reconnect the crack surfaces, thereby achieving partial restoration of mechanical properties.

[0115] The test results are shown in Table 2 below:

[0116] sample Initial resistance to change (MPa) Post-repair resistance (MPa) Self-repair rate Experimental Example 1 72.5 60.3 83.2% Experimental Example 2 78.6 70.1 89.2% Experimental Example 3 75.8 68.9 90.9%

[0117] Table 2 Self-repair rate of each experimental case

[0118] Data Analysis: Repair Rate of Three Experimental Cases All figures exceeded 83%, confirming that the keel of this invention possesses significant self-repair capability. In contrast, the comparative example (galvanized steel keel), once damaged, cannot self-repair, and its performance irreversibly declines. The repair rate is positively correlated with the content of the repair microcapsules (Example 1 had the lowest content and the lowest relative repair rate; Example 3 had the highest content and the highest repair rate), demonstrating that the amount of microcapsules added is a key factor affecting the repair effect. By adjusting this parameter, the repair capability of the keel can be customized.

[0119] Test 3: Comprehensive durability verification.

[0120] Test method: Experiment 2 was tested cyclically, with the following applied: ,frequency Cyclic load 10 5 Next, measure the remaining output voltage. The system was repaired at 60℃ for 24 hours, and the output voltage was measured again after recovery. .

[0121] Long-term cyclic loading can cause microcracks and interfacial debonding within composite materials, leading to degradation of the conductive / piezoelectric network and affecting the output signal. The self-healing process can not only repair structural cracks, but also partially restore conductive pathways (carbon nanotube networks) and electromechanical coupling paths that have been broken due to micro-damage, thereby restoring electrical properties.

[0122] Test results: Initial output voltage before cycle , loop 10 5 The output voltage after this (Performance degradation of approximately 28.5%), output voltage after repair. (Performance recovered to 88.5% of initial value).

[0123] Data Analysis: This test comprehensively verified the long-term operational stability and functional recoverability of the keel. After simulating long-term vibration, its energy harvesting capacity decreased, but after repair treatment, its performance was largely restored. This proves that the present invention is not only a one-time self-healing device, but also achieves functional sustainability, ensuring the reliability of its intelligent functions throughout the entire building life cycle, and solving the problem of irreversible performance degradation of traditional components over time.

[0124] Experimental Conclusions: Experiments 1-3 successfully achieved the three major functions that traditional keel (CE) does not possess: energy harvesting (maximum output 4.1V), self-sensing (generating electrical signal response to stress), and self-repair (repair rate up to >90%). By adjusting the component content (such as piezoelectric ceramics, microcapsules) and process conditions (such as magnetic field strength), the performance level of the final product can be effectively controlled. The keel is transformed from a passive component into an active element with sensing, power supply, and self-maintenance capabilities. The electrical energy it generates can power microwatt-level sensors, and its self-repair capability can significantly extend its service life and reduce maintenance costs, making it extremely valuable in practice.

[0125] The embodiments described above are merely illustrative of specific implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for manufacturing integrated floor slab ceiling joists, characterized in that, Includes the following steps: S1. Mix and stir 50-70 parts by weight of bio-based epoxy resin prepolymer, 20-30 parts by weight of polyurethane modifier, 5-10 parts by weight of reactive diluent and 1-3 parts by weight of curing accelerator at 60-80℃ for 20-40 minutes to obtain liquid matrix material A. S2. Add 2-5 parts by weight of piezoelectric ceramic particles, 1-3 parts by weight of magnetic iron oxide nanoparticles, 3-8 parts by weight of repair microcapsules, 0.5-2 parts by weight of carbon nanotubes and 0.1-0.5 parts by weight of dispersant to the liquid matrix material A obtained in step S1, transfer it to an ultrasonic dispersion device, and ultrasonically disperse it for 30-60 minutes under the conditions of ultrasonic power of 500-800W and temperature of 40-60℃ to obtain a uniformly dispersed composite slurry B. S3. Inject the composite slurry B into the cavity of the keel forming mold, place the mold in a uniform steady magnetic field with an intensity of 0.3-0.8T, with the magnetic field direction parallel to the length direction of the keel, and let it stand for 5-15 minutes to allow the magnetic iron oxide nanoparticles to align along the magnetic field direction, which in turn drives the piezoelectric ceramic particles and carbon nanotubes to oriented and form a preform C. S4. Place the preform C together with the mold under ultraviolet light with a wavelength of 365nm for 10-20 minutes to perform surface photocuring; then perform step-by-step thermal curing: keep at 60℃ for 1 hour, then raise the temperature to 80℃ and keep at 80℃ for 2 hours, and finally raise the temperature to 100℃ and keep at 1 hour to obtain the fully cured keel blank D. S5. On the two opposite sides of the keel blank D, a layer of aluminum film with a thickness of 50-200nm is deposited as an electrode by magnetron sputtering; then, a transparent insulating encapsulating adhesive is coated on the electrode surface and cured at 80℃ for 30 minutes to form a protective layer, thus obtaining the ceiling keel.

2. The manufacturing method according to claim 1, characterized in that, In step S1, the bio-based epoxy resin prepolymer is cashew phenol glycidyl ether or soybean oil-based epoxy resin with an epoxy value of 0.4-0.6 eq / 100g; the polyurethane modifier is a hydroxyl-terminated polyurethane prepolymer with a molecular weight of 2000-5000 g / mol; the reactive diluent is 1,4-butanediol diglycidyl ether; and the curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

3. The manufacturing method according to claim 1, characterized in that, In step S2, the piezoelectric ceramic particles are lead zirconate titanate or potassium sodium niobate with a particle size of 1-10 μm; the magnetic iron oxide nanoparticles have a particle size of 20-100 nm; the carbon nanotubes are multi-walled carbon nanotubes with a length of 5-20 μm and a diameter of 10-20 nm; and the dispersant is a polyoxyethylene type nonionic surfactant.

4. The manufacturing method according to claim 1, characterized in that, In step S2, the core of the repaired microcapsule is an uncured bio-based epoxy resin prepolymer, and the capsule wall is urea-formaldehyde resin. The preparation method of the repair microcapsules is as follows: The microcapsules were prepared by in-situ polymerization, using a mixture of bio-based epoxy resin prepolymer and curing accelerator as the core material and a prepolymer of urea and formaldehyde as the wall material. The reaction was carried out at 50-70℃ for 2-4 hours under the action of emulsifier and acid catalyst. The average particle size of the microcapsules was 50-200μm and the wall thickness was 2-10μm.

5. The manufacturing method according to claim 1, characterized in that, In step S3, a uniform steady-state magnetic field is generated by passing a direct current through a pair of parallel Helmholtz coils, and the magnetic field strength is... The magnitude is determined by the current flowing through the coil. Control, and their relationship satisfies the formula ,in, The number of turns in a single coil. Let be the radius of the MUHOZ coil.

6. The manufacturing method according to claim 1, characterized in that, In step S4, the stepped thermosetting process follows a curing kinetic model, resulting in a certain degree of curing. With time ,temperature The relationship satisfies the modified Kamal equation to achieve internal stress minimization and complete curing.

7. The manufacturing method according to claim 1, characterized in that, In step S5, the process parameters for magnetron sputtering aluminum film deposition are: the base vacuum degree is not higher than 5.0 × 10⁻⁶. −3 The sputtering working pressure is 0.5-1.0a, the argon flow rate is 20-40sccm, the sputtering power is 100-200W, and the sputtering time is 10-30 minutes.

8. The manufacturing method according to claim 1, characterized in that, Following step S5, step S6 is also included: The frequency of the prepared ceiling keel sample was applied to it. Peak value is A sinusoidal alternating load was subjected to a test to measure its open-circuit output voltage. and according to the formula Calculate its effective piezoelectric constant To quantitatively calibrate its energy harvesting performance, among which, The relative permittivity of the ceiling keel sample is given. The vacuum permittivity, This refers to the effective area of ​​the conductive electrode plate that participates in charge collection and is actually connected to the external measurement circuit in the aluminum film electrode deposited on the surface of the keel blank D by magnetron sputtering. The thickness of the ceiling keel sample between the two electrodes.

9. An integrated floor slab with an internal ceiling joist, characterized in that, It is produced by the manufacturing method according to any one of claims 1-8.

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