Preparation method of large-area piezoelectric single crystal composite material

Abstract

The invention discloses a preparation method of a large-area piezoelectric single-crystal composite material. The preparation method comprises the following steps: 3D-printing a glue-pouring Cutting a single crystal block with a specified size; fixing the single crystal block on a glue pouring fixing mold; pouring epoxy resin, and polishing to obtain spliced single crystals; cutting is carried out at a specified lower cutter position; epoxy resin is poured, and the surface is ground and polished; plating an electrode, and carrying out polarization to prepare a large-area 1-3 type piezoelectric single crystal composite material; the 1-3 type piezoelectric single crystal composite material with large area and good uniformity can be prepared, the preparation time is short, the piezoelectric single crystal loss is small, and the prepared cylinder is more regular.

Description

Technical Field

[0001] The invention belongs to the technical field of piezoelectric composite materials, and in particular relates to a method for preparing a large-area piezoelectric single crystal composite material. Background Art

[0002] Piezoelectric composites are composite materials formed by a piezoelectric phase composed of piezoelectric materials and a polymer phase composed of epoxy resin or other polymers with a certain interconnected structure. In 1-3 type composite materials, 1 represents one-dimensional connectivity, that is, connectivity in only one direction, generally linear, which is a piezoelectric phase; 3 represents three-dimensional connectivity, generally connected front and back in three directions, which is a polymer phase. 1-3 type piezoelectric composites have purer thickness vibration, lower impedance, lower mechanical quality factor, and higher bandwidth. It is precisely because of the above advantages that 1-3 type piezoelectric composites have been widely used.

[0003] The piezoelectric constant of a piezoelectric single crystal far exceeds that of piezoelectric ceramics (600pC / N), reaching over 3000pC / N. Although the preparation process of large-area, well-uniform piezoelectric ceramics is mature, the growth of piezoelectric single crystals still faces the problem of small area and poor uniformity. Therefore, currently, using a process similar to that of piezoelectric ceramic composites, only small-area, well-uniform 1-3 type piezoelectric single crystal composites can be prepared, which is difficult to meet the material requirements of high-performance underwater acoustic transducers.

[0004] In order to prepare a large area of ​​1-3 type piezoelectric single crystal composite material, a patent application (publication number CN113659070A) discloses a piezoelectric single crystal composite material and its preparation method and application, using a 3D printing splicing method, the screened piezoelectric single crystal material cylinders are respectively inserted into the spaces of the resin mold to obtain a combination of the resin mold and the piezoelectric material cylinder, and a large area of ​​1-3 type piezoelectric single crystal composite material is prepared. However, the above-mentioned prior art has the following disadvantages:

[0005] (1) This process involves the screening of cut piezoelectric single crystal columns based on their piezoelectric constants. However, the range of the piezoelectric constant of the column is too large, with the difference between the maximum and minimum values ​​being as high as 800pC / N, while the application requirement is only a fluctuation range of 100pC / N. In order to meet the demand, only the interval with the largest piezoelectric constant in this range is selected, which results in less than one-fifth of the columns being effectively utilized, resulting in large single crystal losses and high production costs;

[0006] (2) Since the area of ​​the prepared composite material is too large, more than 5,000 piezoelectric single crystal columns need to be assembled and inserted. In addition, since the piezoelectric single crystal columns are too thin, the labor efficiency is low and the preparation cycle is long. It takes three weeks to prepare a large-area 1-3 type piezoelectric single crystal composite material, and most of the time is manual time.

[0007] (3) Since the 3D printed assembly mold has elasticity, the piezoelectric single crystal small columns inserted into it are often regular on a macroscopic level due to this elasticity, but poorly regular on a microscopic level, which affects the performance. Summary of the invention

[0008] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a method for preparing a large-area piezoelectric single crystal composite material. The composite material is prepared by a splicing method, which solves the problem of excess gaps between blocks in the traditional splicing process. It has the characteristics of short production cycle, small single crystal loss, and the prepared composite material is more regular.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] A method for preparing a large-area piezoelectric single crystal composite material comprises the following steps:

[0011] Step S1, preparing a photosensitive resin 3D printing glue-filling fixed mold;

[0012] Step S2: Orient the piezoelectric single crystal material with good uniformity to ensure that the sample can

[0014] Enough along

[011] ,

[100] , Three key crystal directions are precisely cut to maximize material performance; the good uniformity means that the fluctuation range of the piezoelectric constant in the piezoelectric single crystal material is ±100pC / N;

[0015] Step S3, during precise cutting, cutting is performed according to an integral multiple of the piezoelectric phase period of the desired 1-3 type piezoelectric single crystal composite material, and cleaning and drying are performed to obtain cleaned, dried and cut piezoelectric single crystal small pieces;

[0016] Step S4, placing the cleaned, dried and cut piezoelectric single crystal pieces in the mold of step S1 and fixing them, and pressing the edges tightly to reduce the gaps, to obtain a spliced ​​single crystal;

[0017] Step S5, using epoxy resin to bond the spliced ​​single crystals and wait for them to solidify to ensure that they are stable and do not fall off;

[0018] Step S6, polishing the surface of the spliced ​​single crystal and removing the photosensitive resin 3D printing glue-filling fixed mold to obtain a large-area piezoelectric single crystal sample;

[0019] Step S7, accurately cutting the fixed large-area piezoelectric single crystal sample, cutting from the edge of the spliced ​​single crystal block, and the cutting position is half of the width of the blade to ensure that the bonded epoxy resin can be accurately cut to obtain the cut single crystal material;

[0020] Step S8, cleaning and drying the cut single crystal material, filling the cut gap with epoxy resin and curing;

[0021] Step S9, polishing to remove the epoxy resin on the surface of the product of step S8, and cleaning and drying;

[0022] Step S10, polarizing the product of step S9, and finally obtaining a large-area 1-3 type piezoelectric single crystal composite material.

[0023] The photosensitive resin 3D printing glue pouring fixed mold comprises a splicing mold 1 with a fixed bottom plate and an L-shaped side panel, and two rectangular block fixing plates 2; the rectangular block fixing plates 2 are respectively arranged on the other two sides of the splicing mold 1, and form a square storage tightening frame with the L-shaped splicing mold 1.

[0024] The epoxy resin is Epoxy301.

[0025] In the step S3, the integer multiple of the piezoelectric phase period is specifically an integer multiple of the column width + the slit width of the desired 1-3 type piezoelectric single crystal composite material.

[0026] The fixing in step S4 is performed by fixing it on the fixed bottom plate of the mold by paraffin.

[0027] In the step S10, the electric field strength used for polarization is 6-10 kV / cm, the polarization temperature is 60-80° C., and the polarization time is 10-15 min.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) In step S2 and step S3, the present invention uses a piezoelectric single crystal block with good uniformity for cutting, and the utilization rate is as high as more than one-half, which is far higher than the one-fifth utilization rate of the traditional screening of piezoelectric single crystal small columns;

[0030] (2) Steps S3 and S7 of the present invention successfully solve the problem of excess gaps between blocks in the traditional splicing process by making the piezoelectric single crystal block an integer multiple of the composite material period and accurately selecting the cutting knife position, thereby becoming a new and efficient process for preparing large-area 1-3 type piezoelectric single crystal composite materials.

[0031] (3) In step S7 of the present invention, since the sample retains the base after cutting, the blade stress and microcracks are significantly reduced, so that the uniformity of the material is significantly better than the method of directly cutting into piezoelectric single crystal small columns (fluctuation up to 800pC / N). Since the single crystal is screened by the splicing method, the uniformity of the two processes is not much different. However, the single crystal utilization rate of the present invention is higher, which significantly reduces the production cost.

[0032] (4) Steps S3 and S7 of the present invention significantly reduce the labor intensity by directly cutting the spliced ​​single crystal blocks, rather than cutting them into single crystal small columns and then splicing them. Therefore, the time for preparing large-area 1-3 type piezoelectric single crystal composite materials is shortened from the previous three weeks to about three days.

[0033] (5) Since the present invention does not require an assembly mold, the degree of labor is low and, from a microscopic perspective, the large-area 1-3 type piezoelectric single crystal composite material prepared by the 3D printing splicing method proposed in the present invention is more regular than the traditional 3D printing assembly method.

[0034] In summary, the composite material prepared by the splicing method of the present invention has a short production cycle, small single crystal loss, and the prepared composite material is more regular. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the 3D printed L-shaped mold.

[0036] Figure 2 Schematic diagram of the 3D printed splicing mold.

[0037] Figure 3 Schematic diagram of splicing single crystal blocks and then fixing them in a mold.

[0038] Figure 4 Schematic diagram of the spliced ​​single crystal.

[0039] Figure 5 Schematic diagram of preparing a single crystal for cutting. DETAILED DESCRIPTION

[0040] This embodiment prepares a large-area 1-3 type piezoelectric composite material whose piezoelectric phase is a PIN-PMN-PT single crystal, comprising the following steps:

[0041] Step S1, using photosensitive resin to 3D print a splicing mold 1 with a fixed bottom plate and an L-shaped side panel, and two 80mm×15mm×2.5mm rectangular block fixing plates 2.

[0042] Step S2, taking a piezoelectric single crystal block material, the fluctuation range of the piezoelectric constant in the single crystal block material is ±100pC / N; the size is 30mm×30mm×6mm, and the single crystal material is oriented to ensure that the sample can be along

[011] ,

[100] , Precise cutting in three key crystal directions;

[0043] Step S3, using a precision cutting machine to cut the single crystal block material to ensure dimensional accuracy, the single crystal obtained in step S2 is cut into single crystal small blocks of 14.6 mm×14.6 mm×6 mm, a total of 25 blocks.

[0044] Step S4, placing the small single crystal pieces obtained in step S3 in the mold of step S1 and fixing them, and pressing the edges tightly to reduce the gaps, so as to obtain a spliced ​​single crystal;

[0045] Specifically, each block is glued with paraffin wax on the bottom and bonded to the fixed mold made in step S1, and 5 rows are spliced ​​in the order of 1 row and 5 blocks. When each single crystal block is adhered to the glass sheet, sufficient force must be applied to fully splice it with the previous single crystal block;

[0046] Step S5, using the two L-shaped molds printed in step S1, the spliced ​​single crystals in step S4 are bonded with epoxy resin and fixed firmly to form a square shape; after pouring with Epoxy301 epoxy resin, the single crystal material needs to be placed in a vacuum environment and cured at room temperature for 24 hours;

[0047] Step S6, polishing the surface of the spliced ​​single crystal and removing the photosensitive resin 3D printing glue-filling fixed mold to obtain a large-area piezoelectric single crystal sample;

[0048] Step S7, the spliced ​​single crystal obtained in step S6 is cut by a precision cutting machine. The knife width is 0.3mm, the first knife step is 0.80mm, the second knife step is 0.66mm, and the period is 1.46mm. The first knife must be at the edge of the spliced ​​single crystal, and the cutting position should be controlled at approximately half of the blade width, that is, the cutting depth is 0.16mm. In view of the fact that the side length of the single crystal block is an integer multiple of the cutting period, when cutting the second single crystal, the cutting depth of the first knife needs to be adjusted to (0.16-seam width) mm. However, since the seam width is less than 0.03mm, when cutting to the 7th single crystal, the seam width will no longer be cut, and the splicing method cannot be continued.

[0049] Step S8, the single crystal prepared in step S8 is cleaned twice with anhydrous alcohol, each time for 5 minutes, and then the single crystal material is placed in a vacuum environment and cured at room temperature for 24 hours after being filled with Epoxy301 epoxy resin.

[0050] Step S9, polishing to remove the epoxy resin on the surface of the product of step S8, polishing to the required thickness, cleaning and drying; then plating electrodes on both sides of the sample.

[0051] Step S10, then polarize the product of step S9. During the polarization process, the electric field strength used for polarizing the wafer is 8 kV / cm, the polarization temperature is 80° C., and the polarization time is 10 min.

[0052] In summary, the present invention cuts at integer multiples of the composite material period and accurately selects the cutting position, successfully solving the problem of excess gaps between blocks in the traditional splicing process, thus becoming a new and efficient process for preparing large-area 1-3 type piezoelectric single crystal composite materials.

Claims

1. A method for preparing a large-area piezoelectric single crystal composite material, characterized in that: 3D printing a glue-filling fixed mold; cutting a single crystal block of a specified size according to an integer multiple of the piezoelectric phase period of the required 1-3 type piezoelectric single crystal composite material; fixing the single crystal block on the glue-filling fixed mold; pouring epoxy resin, grinding, and obtaining a spliced ​​single crystal; cutting from the edge of the spliced ​​single crystal block, the cutting position is half of the blade width, and cutting; pouring epoxy resin, grinding and polishing its surface; Electrodes are plated and polarization is performed to obtain a large area of ​​1-3 type piezoelectric single crystal composite material.

2. The method for preparing a large-area piezoelectric single crystal composite material according to claim 1, characterized in that: The following steps are involved: Step S1, preparing a photosensitive resin 3D printing glue-filling fixed mold; Step S2: Orient the piezoelectric single crystal material with good uniformity to ensure that the sample can Enough along [011], [100], Three key crystal directions are precisely cut to maximize material performance; the good uniformity means that the fluctuation range of the piezoelectric constant in the piezoelectric single crystal material is ±100pC / N; Step S3, during precise cutting, cutting is performed according to an integral multiple of the piezoelectric phase period of the desired 1-3 type piezoelectric single crystal composite material, and cleaning and drying are performed to obtain cleaned, dried and cut piezoelectric single crystal small pieces; Step S4, placing the cleaned, dried and cut piezoelectric single crystal pieces in the mold of step S1 and fixing them, and pressing the edges tightly to reduce the gaps, to obtain a spliced ​​single crystal; Step S5, using epoxy resin to bond the spliced ​​single crystals and wait for them to solidify to ensure that they are stable and do not fall off; Step S6, polishing the surface of the spliced ​​single crystal and removing the photosensitive resin 3D printing glue-filling fixed mold to obtain a large-area piezoelectric single crystal sample; Step S7, accurately cutting the fixed large-area piezoelectric single crystal sample, cutting from the edge of the spliced ​​single crystal block, and the cutting position is half of the width of the blade to ensure that the bonded epoxy resin can be accurately cut to obtain the cut single crystal material; Step S8, cleaning and drying the cut single crystal material, filling the cut gap with epoxy resin and curing; Step S9, polishing to remove the epoxy resin on the surface of the product of step S8, and cleaning and drying; Step S10, polarizing the product of step S9, and finally obtaining a large-area 1-3 type piezoelectric single crystal composite material.

3. The method for preparing a large-area piezoelectric single crystal composite material according to claim 2, characterized in that: The photosensitive resin 3D printing glue pouring fixed mold comprises a splicing mold (1) with a fixed bottom plate and an L-shaped side panel, and two rectangular block fixing plates (2); the rectangular block fixing plates (2) are respectively arranged on the other two side surfaces of the splicing mold (1), and together with the L-shaped splicing mold (1) form a square storage tightening frame.

4. The method for preparing a large-area piezoelectric single crystal composite material according to claim 2, characterized in that: The epoxy resin is Epoxy301.

5. The method for preparing a large-area piezoelectric single crystal composite material according to claim 2, characterized in that: In the step S3, the size of the cut single crystal is an integer multiple of the piezoelectric phase period, specifically an integer multiple of the column width + the slit width of the required 1-3 type piezoelectric single crystal composite material.

6. The method for preparing a large-area piezoelectric single crystal composite material according to claim 2, characterized in that: The fixing in step S4 is performed by fixing it on the fixed bottom plate of the mold by paraffin.

7. The method for preparing a large-area piezoelectric single crystal composite material according to claim 2, characterized in that: In the step S10, the electric field strength used for polarization is 6-10 kV / cm, the polarization temperature is 60-80° C., and the polarization time is 10-15 min.

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