Bicontinuous structure piezoelectric ceramic / cement piezoelectric composite material and preparation method thereof

Abstract

The application discloses a kind of bicontinuous structure piezoelectric ceramic / cement piezoelectric composite material and preparation method thereof, the bicontinuous structure piezoelectric ceramic / cement piezoelectric composite material includes mutually combined piezoelectric ceramic material and cement material, the piezoelectric ceramic material and cement material are three-dimensional network structure, the average curvature of all points on the curved surface of the three-dimensional network structure is zero, and it has periodicity in three directions of three-dimensional the bicontinuous structure piezoelectric ceramic / cement piezoelectric composite material of the application can be endowed with more function and performance for material using bicontinuous structure, including enhancing the piezoelectric effect of material, improving the durability of material etc..By reasonably designing bicontinuous structure, the multifunctional performance optimization of cement-based piezoelectric ceramic plate can be realized, to adapt to the engineering demand of cement-based pavement energy storage.

Description

Technical Field

[0001] The present invention relates to the technical field of cement-based piezoelectric composites, and particularly relates to a double-continuous structure piezoelectric ceramic / cement piezoelectric composite and a preparation method thereof. Background Art

[0002] The research and development of cement-based piezoelectric composites can be traced back to the 1990s. Initially, piezoelectric materials were mainly applied in the fields of electronic devices and sensors, while cement-based materials were mainly used in construction engineering. With the progress of technology, researchers began to explore combining piezoelectric ceramics with cement to create a new type of functional material. It has the durability of cement-based materials and the functional characteristics of piezoelectric materials, so it has broad application prospects in the fields of structural health monitoring, energy harvesting, and sensors. Currently, the common structures of cement-based piezoelectric composites on the market are 0-3 type and 1-3 type. The 0-3 type cement-based piezoelectric composite refers to a composite material formed by dispersing piezoelectrically active ceramic particles in a three-dimensionally continuous cement matrix. The piezoelectric properties of the 0-3 type cement-based piezoelectric composite are usually low because the piezoelectric ceramic particles are randomly dispersed in the cement matrix, which limits the piezoelectric effect and sensing performance of the material. The 1-3 type cement-based piezoelectric composite is a two-phase piezoelectric composite composed of one-dimensional piezoelectric ceramic columns arranged parallel to each other in a three-dimensionally connected cement matrix. Due to the change in structure, the piezoelectric properties have been improved. Although great progress has been made in the research of cement-based piezoelectric composites, there are still many problems to be solved. For example, the spatial discontinuity of the cement-based piezoelectric ceramic phase leads to poor load transfer from the surrounding cement matrix to the ceramic filler, which greatly limits its piezoelectric properties. Summary of the Invention

[0003] In view of the above problems, the present invention studies and designs a double-continuous structure piezoelectric ceramic / cement piezoelectric composite and a preparation method thereof. The technical means adopted by the present invention are as follows:

[0004] A double-continuous structure piezoelectric ceramic / cement piezoelectric composite, comprising a piezoelectric ceramic material and a cement material combined with each other. The piezoelectric ceramic material is a three-dimensional network structure, and the average curvature of all points on the surface of the three-dimensional network structure is zero, and it has periodicity in three directions in three dimensions.

[0005] Further, the three-dimensional network structure of the piezoelectric ceramic material is composed of one or more than two cells, and the cell conforms to the following formula:

[0006] f(x,y,z) = n, 0 < n < 1; where

[0007] coswx + coswy + coswz = n, or

[0008] 3×(coswx+coswz+coswy)+4×coswx×coswz×coswy=n,

[0009] Where x, y, z are spatial coordinates, ω = 2π / l, l is the length of the cell, and f is the ratio of the volume of the piezoelectric ceramic material to the overall volume.

[0010] Furthermore, the volume fraction of piezoelectric ceramic material in the piezoelectric composite material is 10% to 20%.

[0011] Furthermore, the piezoelectric ceramic material is lead zirconate titanate ceramic, and the cement material is silicate cement.

[0012] A method for preparing a dual-continuous structure piezoelectric ceramic / cement piezoelectric composite material, used to prepare the dual-continuous structure piezoelectric ceramic / cement piezoelectric composite material of the present invention, includes the following steps:

[0013] S1: A three-dimensional solid model is obtained by curing a mixture of piezoelectric ceramic particles and photosensitive resin using photopolymerization 3D printing technology.

[0014] S2: Sinter the three-dimensional solid model obtained in step S1, sinter it until it is dense and then cool it in the furnace to obtain a dual continuous piezoelectric ceramic material.

[0015] S3: Fill the pores of the piezoelectric ceramic material obtained in step S2 with cement paste and allow it to solidify completely to form a bicontinuous structure piezoelectric ceramic / cement piezoelectric composite material.

[0016] Compared with existing technologies, the dual-continuous structure piezoelectric ceramic / cement piezoelectric composite material of this invention, by employing a dual-continuous structure, can endow the material with more functions and properties, including enhancing the piezoelectric effect and improving the material's durability. Through rational design of the dual-continuous structure, the multi-functional performance optimization of cement-based piezoelectric ceramic plates can be achieved, thereby meeting the engineering requirements of energy storage in cement-based pavements. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the overall design and analysis method of this invention.

[0018] Figure 2 The bicontinuous primitive (DP) and bicontinuous Neovius (DN) geometric figures created by the bicontinuous structure mathematical equations in this embodiment of the invention;

[0019] Figure 3 , Figure 4 , Figure 5 and Figure 6 These are four different ceramic-structured cement-based piezoelectric composite materials created using finite element software in embodiments of the present invention.

[0020] Figure 7 This is a schematic diagram illustrating the measurement of the piezoelectric response of a three-dimensional cement-based piezoelectric composite material under cyclic pressure, according to an embodiment of the present invention.

[0021] Figure 8a In this embodiment of the invention, the average piezoelectric coefficient of four different structural cement-based piezoelectric composite material plates under pedestrian load was simulated using finite element software.

[0022] Figure 8b In this embodiment of the invention, the average piezoelectric coefficient of four different structural cement-based piezoelectric composite material plates under vehicle load was simulated using finite element software.

[0023] Figure 9a In this embodiment of the invention, the piezoelectric voltage coefficients of four different cement-based piezoelectric composite material plates with pedestrian load weight were simulated using finite element software.

[0024] Figure 9b In this embodiment of the invention, the piezoelectric voltage coefficients of four different structural cement-based piezoelectric composite material plates under vehicle load were simulated using finite element software. Detailed Implementation

[0025] This invention compares four cement-based composite materials with different internal piezoelectric ceramic structures and performs numerical simulations and finite element analysis. The bicontinuous structure geometry is defined as having an average curvature of zero at every point on the surface, consisting of interpenetrating and non-intersecting networks with a periodic and ordered topology in three main directions and symmetry in the crystal space group. The design and analysis method flow of this embodiment is as follows: Figure 1 As shown. Among them, two bicontinuous structures, primitive (DP) and bicontinuous Neovius (DN), were selected. The complex and logically inherent bicontinuous structure can be described by mathematical expressions. The geometric figures are created by extracting from mathematical equations (1) and (2), that is, the shapes defined by f=0. The shapes of DP and DN can be mathematically expressed by the following formulas, which are given below:

[0026] DP: f(x,y,z)=coswx+coswy+coswz (1)

[0027] DN: f(x,y,z)=3×(coswx+coswz+coswy)+4×coswx×coswz×coswy (2)

[0028] Figure 2The diagram displays the 3D models of the created DP and DN geometries. x, y, z are spatial coordinates; the equations define the DP and DN shapes as cubic cells; ω = 2π / l, where l is the cell length; and f is defined as the ratio of the internal sub-volume (the volume of the piezoelectric ceramic material) to the overall volume. The 3D mesh structure of the piezoelectric ceramic material can contain one or more cells.

[0029] In this embodiment, MATLAB code was developed to define the structural equations for DP and DN and determine the frame volume fraction of the geometry, where the piezoelectric ceramic content in the cement-based material was set to 10%, 15%, and 20%. Then, the cement-based piezoelectric composite material was numerically simulated using the commercial finite element software Abaqus, and modeling and finite element analysis were performed using this software. In the model mesh generation, hexahedral elements could not represent the smooth shape of the DP and DN surface structures; therefore, linear tetrahedral elements (C3D4E) were used for modeling. The model element for the cement-based piezoelectric composite material was a cube with a side length of 50 mm.

[0030] In the simulation process, the choice of materials has a crucial impact on the performance of cement-based piezoelectric composites. Initially, materials exhibiting piezoelectric effects were only found in crystalline structures such as tourmaline, quartz, and Rochelle salts; however, their applications were limited due to low efficiency and high brittleness. In this patent study, lead zirconate titanate (PZT-7A) ceramic was used because of its strong piezoelectric properties. Furthermore, silicate cement, whose main components are calcium silicate and mineral powder, possesses characteristics such as high strength, good durability, and good plasticity, and is used as the matrix for the composite material. Figure 3 , Figure 4 , Figure 5 , Figure 6 Four different ceramic structures of cement-based piezoelectric composite materials were created using finite element software in this embodiment of the invention, namely type 0-3, type 1-3, DP structure, and DN structure. Figures 3 to 6 As shown, PZT-7A ceramic 1 (green part) is embedded in cement 2 (red part) to form a cement-based piezoelectric composite material. The relevant parameters of the cement-based piezoelectric composite material are listed in Tables 1 and 2.

[0031] Table 1 Mechanical properties of lead zirconate titanate ceramics and silicate cement

[0032]

[0033] Table 2 Piezoelectric coefficients of lead zirconate titanate ceramics and silicate cement

[0034]

[0035] Next, the piezoelectric response of the three-dimensional cement-based composite material under periodic compression was measured. Figure 7By performing finite element modeling of the stress and piezoelectric coefficient of the composite material, the piezoelectric response of the composite material can be clearly observed. In our model, the piezoelectric ceramic is an isotropic elastic material with its polarization direction perpendicular to the surface of the cement-based composite material. A representative simulated cell (RVE) is formed by periodically connecting Kelvin cells. Figure 7 As shown, the piezoelectric response of a car on a cement slab was simulated. For complex models with periodic microstructures, periodic boundary conditions should be added before finite element numerical calculations. The average performance of representative elements is used to represent the overall structural performance. The displacement at the boundary of a periodic element can be expressed as:

[0036]

[0037]

[0038] This patent utilizes the piezoelectric constitutive equation that couples mechanical and electric fields, and its formula is as follows:

[0039] {D}=[d]{σ}+[χ]{E}; (5)

[0040] {ε}=[S]{σ}+[d]{E}; (6)

[0041] In the formulas: {ε} is the strain exponent; {σ} is the stress exponent; [S] is the elastic compliance matrix; [d] is the piezoelectric matrix, in Coulombs / Newtons; {E} is the applied electric field, in V / m; [χ] is the dielectric constant matrix; and {D} represents the induced dielectric displacement per unit electric field. Equations (5) and (6) can also be expressed as:

[0042]

[0043]

[0044] Equation (9) is the most commonly used representation of the constitutive equation of piezoelectric materials. Furthermore, for piezoelectric material layers with polarization along their thickness, the piezoelectric coefficient d has only six independent entries given in matrix form, as shown below:

[0045]

[0046] piezoelectric voltage coefficient G 33 Calculated by the following formula:

[0047]

[0048] Subsequently, the average piezoelectric coefficients of cement-based piezoelectric composites with four different piezoelectric ceramic geometries were compared, and the average piezoelectric coefficient d was calculated using Equation 5-6. 33First, the weights of pedestrians and cars traveling on the concrete slab were simulated, with 0.7 and 15 kN of weight added to the surface along the polarization direction, respectively. Figure 8 shows the average piezoelectric coefficient d for the DP structure, DN structure, 0-3 type structure, and 1-3 type structure. 33 The bar chart shows that the average piezoelectric coefficient of the cement-based composite materials with four different piezoelectric ceramic structures is linearly proportional to the piezoelectric ceramic content. Clearly, the higher the content of PZT-7A ceramic, the greater the average piezoelectric coefficient of the cement-based piezoelectric composite material. Figure 8a As shown, under pedestrian weight, with a piezoelectric ceramic volume fraction of 20%, the DP and DN structures can achieve 87 pc / N and 103 pc / N, respectively. This indicates that the average piezoelectric coefficient of the cement-based piezoelectric composite material with the new structure is higher than that of the 0-3 type (7 pc / N) and 1-3 type (37 pc / N). Similarly, the average piezoelectric coefficient under vehicle weight was compared... Figure 8b The piezoelectric properties of DP and DN structures are still far superior to those of traditional cement-based piezoelectric composites. Furthermore, we calculated the piezoelectric voltage coefficient G for several structures. 33 ,like Figure 9a and Figure 9b As shown. Figures 8a to 9b In the diagram, the four bars in each group correspond from left to right to the 0-3 type, 1-3 type, DP structure, and DN structure, respectively. The bar charts show that both the DP and DN structures exhibit good piezoelectric properties. The DN structure achieves the best performance, with a piezoelectric voltage coefficient of 36.4 × 10⁻⁶ when the piezoelectric ceramic volume fraction is 20%. -3 V / mPa. The main reason is that the discontinuity and random distribution of piezoelectric ceramic materials directly affect their piezoelectric properties. DP and DN structures have very smooth surfaces, and structures with smooth surfaces typically exhibit low resistance or high conductivity. Clearly, both DP and DN structures exhibit extremely high piezoelectric performance. We conclude that the shape of piezoelectric ceramic materials also plays a crucial role in improving the performance of cement-based piezoelectric composites. This is mainly because the bicontinuous structure possesses ordered periodicity and three-dimensional interconnected channels, which facilitates efficient mass transport and diffusion within the material. It also provides continuous paths and a large specific surface area, enabling rapid ion transport and diffusion, thereby improving the utilization rate of active sites within the material. This can bring high specific capacity and excellent rate performance to cement-based piezoelectric composite plates.

[0049] This embodiment employs photopolymerization 3D printing technology to solidify a mixture of piezoelectric ceramic particles and photosensitive resin. After printing, the printed part undergoes degreasing and heat treatment to obtain a dense, dual-continuous piezoelectric ceramic part with the final properties and dimensions. First, a low-viscosity, high-solids-content slurry is prepared. Then, the slurry is stabilized and photopolymerized in a printer; the entire process is computer-controlled. Printing proceeds layer by layer, from point to line, and from line to surface, repeating this process until the entire dual-continuous structure is completed, resulting in a three-dimensional solid model. Next, the printed piezoelectric ceramic model is sintered in a high-temperature sintering furnace at 1100°C for 2 hours, achieving densification. The model is then cooled in the furnace to obtain the dual-continuous piezoelectric ceramic model. Finally, silicate cement is filled into the pores of the piezoelectric ceramic material, and the model is placed in a standard curing chamber at 20°C for 14 days to allow complete solidification, forming a dual-continuous piezoelectric ceramic / cement piezoelectric composite material.

[0050] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A dual-continuous structure piezoelectric ceramic / cement piezoelectric composite material, comprising piezoelectric ceramic material and cement material bonded together, characterized in that: The piezoelectric ceramic material has a three-dimensional network structure. The average curvature of all points on the surface of the three-dimensional network structure is zero, and it is periodic in three directions. The volume fraction of the piezoelectric ceramic material in the piezoelectric composite material is 10%~20%. The three-dimensional network structure of the piezoelectric ceramic material is composed of one or more cell units, and the cell unit conforms to the following formula: n,0 <n<1; in = n ,or = n， Where x, y, z are spatial coordinates, ω = 2π / l, l is the length of the cell, and f is the ratio of the volume of the piezoelectric ceramic material to the overall volume.

2. The dual continuous structure piezoelectric ceramic / cement piezoelectric composite material according to claim 1, characterized in that: The piezoelectric ceramic material is lead zirconate titanate ceramic, and the cement material is silicate cement.

3. A method for preparing a dual-continuous structure piezoelectric ceramic / cement piezoelectric composite material, used to prepare the dual-continuous structure piezoelectric ceramic / cement piezoelectric composite material according to claim 1 or 2, characterized in that: Includes the following steps: S1: A three-dimensional solid model is obtained by curing a mixture of piezoelectric ceramic particles and photosensitive resin using photopolymerization 3D printing technology. S2: Sinter the three-dimensional solid model obtained in step S1, sinter it until it is dense and then cool it in the furnace to obtain a dual continuous piezoelectric ceramic material. S3: Fill the pores of the piezoelectric ceramic material obtained in step S2 with cement paste and allow it to solidify completely to form a bicontinuous structure piezoelectric ceramic / cement piezoelectric composite material.

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