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CN-122028641-A - 3-1-2 Cement-based piezoelectric composite material and preparation method thereof

CN122028641ACN 122028641 ACN122028641 ACN 122028641ACN-122028641-A

Abstract

A3-1-2 cement-based piezoelectric composite material comprises a piezoelectric ceramic rod, a cement matrix and a piezoelectric ceramic substrate, wherein the structural connectivity is defined as 3-1-2, the 3 phase is the cement matrix and is continuous along all directions as a continuous phase for realizing acoustic impedance matching with concrete, the 1 phase is the piezoelectric ceramic rod which is continuous along the thickness direction and is in a rod shape or column shape and is discretely distributed in the cement matrix, and the 2 phase is the piezoelectric ceramic substrate, and a piezoelectric ceramic rod array is connected with one piezoelectric ceramic substrate in series in the thickness direction to form a stable framework structure with transverse and longitudinal supports. And a preparation method of the 3-1-2 type cement-based piezoelectric composite material. The invention fuses the acoustic matching advantage and the structural stability advantage of the material.

Inventors

  • XU JINAN
  • He Tongzhou
  • QIU HANJIE
  • LI HONGNUO
  • QIAN RUSHENG
  • FU CHUANQING

Assignees

  • 浙江工业大学

Dates

Publication Date
20260512
Application Date
20260211

Claims (6)

  1. 1. A3-1-2 cement-based piezoelectric composite material is characterized by comprising piezoelectric ceramic rods, a cement matrix and piezoelectric ceramic substrates, wherein the structural connectivity is defined as 3-1-2, 3 phases are the cement matrix and are continuous along all directions as continuous phases for realizing acoustic impedance matching with concrete, 1 phase is the piezoelectric ceramic rods which are continuous along the thickness direction and are distributed in the cement matrix in a rod-like or columnar discrete manner, 2 phase is the piezoelectric ceramic substrates, and a piezoelectric ceramic rod array is connected in series with one piezoelectric ceramic substrate in the thickness direction to form a stable framework structure with transverse and longitudinal supports.
  2. 2. A 3-1-2 cement-based piezoelectric composite material according to claim 1, wherein the volume fraction V f of the piezoelectric ceramic rod satisfies 0.2- f -0.4.
  3. 3. A method of preparing a 3-1-2 cement-based piezoelectric composite material according to claim 1, comprising the steps of: step 1, preparing a piezoelectric ceramic rod array, wherein the process is as follows: 1.1, preparing a pre-polarized or to-be-polarized PZT ceramic base block; 1.2, performing precise array cutting on the PZT base block along the thickness direction by using an ultrasonic vibration drilling machine or a high-precision cutting machine to form PZT rod-shaped units which are regularly arranged; Preparing high-performance cement-based slurry, uniformly and fully filling the slurry into array gaps among the PZT rod-shaped units, vibrating and compacting, and performing primary curing under set temperature and humidity to form a PZT/cement composite superstructure with acoustic impedance matching characteristics; Step 2, preparing a piezoelectric ceramic substrate, namely preparing a piezoelectric ceramic substrate matched with the PZT rod array in size, wherein the substrate is used as a mechanical supporting layer and a decoupling layer of the transducer array; Step 3, structure assembly and connection, namely firmly connecting the lower electrode surface of the cured PZT with the upper surface of the piezoelectric ceramic substrate in series through conductive adhesive or welding technology to form a complete 3-1-2 type composite structure; and 4, secondarily polarizing and packaging, namely applying a high-voltage direct-current electric field to the assembled integral composite material to carry out secondary polarization so as to ensure the piezoelectric response performance of the integral structure.
  4. 4. The method according to claim 3, wherein in the step 2, the cement-based slurry contains silica fume or nano silica so as to improve compactness and mechanical strength of the cement matrix.
  5. 5. A method according to claim 3, wherein in step S3, the series connection is performed using a conductive epoxy glue or a soldering process.
  6. 6. A method according to claim 3, wherein in step 4, the side and back surfaces of the composite material are subjected to a waterproof, vibration damping or acoustic reflection backing treatment.

Description

3-1-2 Cement-based piezoelectric composite material and preparation method thereof Technical Field The invention belongs to the technical category of intelligent sensing of structures, multiphase piezoelectric functional materials and nondestructive detection of civil engineering. In particular to a 3-1-2 type cement-based piezoelectric composite material which is specially used for monitoring the health of a concrete structure and has acoustic impedance matching, excellent electromechanical coupling performance and high mechanical stability, and a high-efficiency preparation process for realizing the structural integration of the material. Background Currently, compounding piezoelectric ceramics with polymers is the dominant method of manufacturing acoustic transducers. The traditional 1-3 type piezoelectric composite material (the piezoelectric ceramic rod array is embedded in the polymer matrix) reduces the acoustic impedance of the material to a certain extent, but still has obvious difference with concrete (the acoustic impedance is about 8-12 MRayl), so that the acoustic wave is reflected and energy loss occurs at an interface, and the detection sensitivity is affected. In addition, the polymer matrix has relatively limited mechanical strength, thermal stability and chemical compatibility with concrete, limiting the reliability and lifetime of the sensor in long-term, array-embedded applications within the concrete. However, the above prior art solutions still have the following limitations: The structure and performance integrated degree is insufficient, and the scheme is essentially a three-phase asymmetric composite body of a cement matrix-organic polymer-ceramic framework. The introduction of organic polymers, while enhancing some mechanical properties, still presents challenges for long-term weatherability (e.g., aging, creep) and interfacial stability with cement substrates under temperature and humidity changes, which can affect the long-term service performance of the sensor within the concrete. Furthermore, the presence of the polymer phase introduces uncertainty into the overall acoustic properties of the material, which is detrimental to achieving an optimal acoustic match with the concrete. The mechanical support and decoupling design is deficient, the scheme focuses on improving the performance through the porous framework and the filling phase, but the problem of mechanical stability of the composite material in the transverse direction and the longitudinal direction is not fundamentally solved, and particularly when the composite material bears long-term cyclic load or impact, the performance attenuation can be caused by uneven internal stress distribution. Meanwhile, the lack of a specific structural design for vibration crosstalk (i.e., inter-element decoupling) when the multi-sensing unit (array) is operated limits its application in detection scenarios requiring high spatial resolution. The preparation process has complexity and uniformity that the porous ceramic skeleton is prepared by relying on the sodium alginate ionic gel method, the process control requirement is high, and the uniformity and the repeatability of the skeleton structure are not easy to ensure. Meanwhile, the multi-step composite process of 'cement pouring-polymer filling' is complicated in process, and perfect combination and performance consistency of a three-phase interface are difficult to ensure. Therefore, the civil engineering field is urgent to need a novel piezoelectric composite material and a preparation method thereof, not only better matching with concrete on acoustic impedance, but also higher structural integration degree, excellent mechanical stability and long-term durability are realized, and crosstalk among elements can be effectively inhibited through structural design, so that the severe requirements of long-term, high-precision and array acoustic emission nondestructive inspection in a concrete structure are truly met. The present invention is the innovative solution presented in this context. In the prior art, no technology has been disclosed or put into practical use, which can systematically and integrally design and prepare three phases of a cement-based continuous phase, a piezoelectric ceramic rod array and a piezoelectric ceramic substrate providing transverse and longitudinal mechanical support and decoupling in a 3-1-2 composite structure mode, and is specially used for long-term high-precision acoustic emission nondestructive inspection in a concrete structure. Disclosure of Invention In order to overcome the double defects of mismatching of acoustic impedance and poor structural mechanical stability of a sensor in the prior art, the invention provides a 3-1-2 type cement-based piezoelectric composite material which combines the acoustic matching advantage and the structural stability advantage of the material and a preparation method thereof. The technical scheme adopted for solvi