Preparation method of large-area piezoelectric single crystal composite material

Abstract

A preparation method of a large-area piezoelectric single crystal composite material, a 3D printing glue filling fixing mold; cutting a single crystal block of a specified size; fixing the single crystal block on the glue filling fixing mold; pouring epoxy resin, polishing, obtaining a spliced single crystal; cutting at a specified lower knife position; pouring epoxy resin, polishing and polishing the surface; plating electrodes, polarization, and preparation of a large-area 1-3 type piezoelectric single crystal composite material; the present application can prepare a 1-3 type piezoelectric single crystal composite material with large area and good uniformity, and the preparation time is short, the piezoelectric single crystal loss is small, and the prepared column is more regular.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of piezoelectric composites, and particularly relates to a preparation method of a large-area piezoelectric single crystal composite material. BACKGROUND

[0002] A piezoelectric composite material is a composite material formed by a piezoelectric phase composed of a piezoelectric material and a polymer phase composed of an epoxy resin or other polymers in a certain connected structure. In a 1-3 type composite material, 1 represents one-dimensional connection, that is, only in one direction, generally linear, for the piezoelectric phase; 3 represents three-dimensional direction connection, generally through in front and back in three directions, for the polymer phase. The 1-3 type piezoelectric composite material has purer thickness vibration, lower impedance, lower mechanical quality factor and higher bandwidth. Due to the above advantages, the 1-3 type piezoelectric composite material has been widely applied.

[0003] The piezoelectric constant of a piezoelectric single crystal is far higher than that of a piezoelectric ceramic (600 pC / N), and is as high as 3000 pC / N or more. Although the preparation process of a large-area and uniform piezoelectric ceramic is mature, the growth of a piezoelectric single crystal still faces the problems of small area and poor uniformity. Therefore, at present, by using a process similar to a piezoelectric ceramic composite material, only a small-area and uniform 1-3 type piezoelectric single crystal composite material can be prepared, which is difficult to meet the material requirements of a high-performance underwater acoustic transducer.

[0004] In order to prepare a large-area 1-3 type piezoelectric single crystal composite material, a patent application (publication number CN113659070A) discloses a piezoelectric single crystal composite material and a preparation method and application thereof, which adopts a 3D printing splicing method, inserts the screened piezoelectric single crystal material column into the empty space of the resin mold, obtains a combination of the resin mold and the piezoelectric material column, and prepares a large-area 1-3 type piezoelectric single crystal composite material. However, the above prior art has the following disadvantages:

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

[0006] (2) Since the prepared composite material has a large area, more than 5000 piezoelectric single crystal small columns need to be spliced, and due to the small size of the piezoelectric single crystal small column, the manual efficiency is low, the preparation period is long, and 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) Because the 3D printing splicing mold has elasticity, the piezoelectric single crystal small column spliced in is often regular on the macro level and has poor regularity on the micro level due to the elasticity, which affects the performance. SUMMARY

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

[0009] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0010] A preparation method of a large-area piezoelectric single crystal composite material, comprising the following steps:

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

[0012] Step S2, uniformly good piezoelectric single crystal material is oriented to ensure that the sample can be accurately cut along

[011] ,

[100] ,

[010] and

[001] three key crystal directions to maximize the performance of the material;

[0013] The uniformity of the piezoelectric single crystal material is good, that is, the fluctuation range of the piezoelectric constant in the piezoelectric single crystal material is ±100pC / N;

[0014] Step S3, during accurate cutting, the piezoelectric single crystal small block is cut according to an integer multiple of the piezoelectric phase period of the required 1-3 type piezoelectric single crystal composite material, and then washed and dried to obtain the piezoelectric single crystal small block after washing and drying;

[0015] Step S4, the piezoelectric single crystal small block after washing and drying is placed in the mold of step S1 and fixed, and the edges are tightly pressed to reduce the gap, to obtain the spliced single crystal;

[0016] Step S5, the spliced single crystal is bonded using epoxy resin and allowed to solidify to ensure stability and prevent falling off;

[0017] Step S6, the surface of the spliced single crystal is polished and the photosensitive resin 3D printing glue filling fixing mold is removed to obtain a large-area piezoelectric single crystal sample;

[0018] Step S7, the fixed large-area piezoelectric single crystal sample is accurately cut from the edge of the spliced single crystal block, and the cutting position is at half the width of the cutting edge to ensure that the bonded epoxy resin can be accurately cut to obtain the single crystal material after cutting;

[0019] Step S8, the single crystal material after cutting is washed and dried, and the cutting gap is filled with epoxy resin and solidified; ​

[0020] Step S9, polishing to remove the epoxy resin on the surface of the product of step S8, cleaning and drying;

[0021] Step S10, polarizing the product of step S9, to obtain a large-area 1-3 type piezoelectric single crystal composite material.

[0022] The light-sensitive resin 3D printing glue filling fixing mold comprises a spliced mold 1 with a fixed bottom plate and an L-shaped side fence, and two rectangular block fixed plates 2; the rectangular block fixed plates 2 are respectively arranged on the other two sides of the spliced mold 1, and the L-shaped spliced mold 1 forms a square storage tightening frame as a whole.

[0023] The epoxy resin is Epoxy 301.

[0024] In step S3, the integer multiple of the piezoelectric phase period is specifically an integer multiple of the column width + seam width of the required 1-3 type piezoelectric single crystal composite material.

[0025] In step S4, the fixing is fixed on the fixed bottom plate of the mold by paraffin.

[0026] In step S10, the electric field strength used for polarization is 6-10 kV / cm, the polarization temperature is 60-80 DEG C, and the polarization time is 10-15 min.

[0027] Compared with the prior art, the beneficial effects of the present application are:

[0028] (1) In steps S2 and S3, the present application uses a piezoelectric single crystal block with good uniformity for cutting, and the utilization rate is more than one-half, far exceeding the one-fifth utilization rate of traditional screening of piezoelectric single crystal small columns.

[0029] (2) Steps S3 and S7 of the present application 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 an efficient new process for preparing large-area 1-3 type piezoelectric single crystal composite materials.

[0030] (3) In step S7 of the present application, the sample retains the base after cutting, significantly reducing the generation of blade stress and microcracks, making the uniformity of the material significantly better than the method of directly cutting into piezoelectric single crystal small columns (fluctuation up to 800 pC / N), and 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 application is higher, significantly reducing the production cost.

[0031] (4) The step S3 and the step S7 of the present application cut the spliced monocrystal block directly, instead of cutting the monocrystal small column first and then splicing, which significantly reduces the man-engineering degree, and therefore, the time for preparing the large-area 1-3 type piezoelectric monocrystal composite material is shortened from three weeks to about three days.

[0032] (5) Since the present application does not need a splicing mold, the man-engineering degree is low, and from the microscopic point of view, compared with the traditional 3D printing splicing method, the large-area 1-3 type piezoelectric monocrystal composite material prepared by the 3D printing splicing method of the present application is more regular.

[0033] In summary, the composite material prepared by the splicing method of the present application has a short production cycle, small monocrystal loss, and the prepared composite material is more regular. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a schematic diagram of the L-shaped mold for 3D printing.

[0035] Figure 2 It is a schematic diagram of the splicing mold for 3D printing.

[0036] Figure 3 It is a schematic diagram of splicing the monocrystal block and then fixing it in the mold.

[0037] Figure 4 It is a schematic diagram of the spliced monocrystal.

[0038] Figure 5 It is a schematic diagram of preparing to cut the monocrystal. DETAILED DESCRIPTION

[0039] The present embodiment prepares a large-area 1-3 type piezoelectric composite material with a piezoelectric phase of PIN-PMN-PT single crystal, including the following steps:

[0040] Step S1, a splicing mold 1 with a fixed bottom plate and an L-shaped side wall is 3D printed using photosensitive resin, and two rectangular block fixing plates 2 with a size of 80mmx15mmx2.5mm are used.

[0041] Step S2, take the piezoelectric monocrystal block material, the fluctuation range of the piezoelectric constant in the body of the monocrystal block material is ±100pC / N; the size is 30mmx30mmx6mm, orient the monocrystal material to ensure that the sample can be accurately cut along

[011] ,

[100] , three key crystal directions;

[0042] Step S3, use a precision cutting machine to cut the monocrystal block material to ensure size accuracy, cut the monocrystal obtained in step S2 into 14.6mmx14.6mmx6mm monocrystal small blocks, a total of 25 blocks.

[0043] Step S4, the single crystal small pieces obtained in step S3 are fixed inside the mold of step S1, and the edges are tightly pressed to reduce the gap, to obtain the spliced single crystal;

[0044] Specifically, each bottom is adhered with paraffin, and is adhered to the fixed mold made in step S1, and is spliced in 5 rows according to the order of 1 row and 5 pieces, wherein when each single crystal piece is adhered to the glass sheet, it must be sufficiently spliced with the last single crystal piece by sufficient force;

[0045] Step S5, using the two L-shaped molds printed in step S1, the spliced single crystal of step S4 is adhered and fixed by force to form a mouth-shaped type, and after pouring with Epoxy 301 epoxy resin, the single crystal material needs to be placed in a vacuum environment for 24 hours at room temperature.

[0046] Step S6, polishing the surface of the spliced single crystal and removing the photosensitive resin 3D printing glue fixing mold to obtain a large-area piezoelectric single crystal sample;

[0047] 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 down position must be at the edge of the spliced single crystal, and the cutting position should be controlled at about half of the width of the blade, that is, the depth of cut is 0.16mm. Since the edge length of the single crystal small piece is an integer multiple of the cutting period, therefore, when cutting the second single crystal, the first knife cutting depth needs to be adjusted to (0.16-gap width)mm. However, since the gap width is less than 0.03mm, when cutting to the 7th single crystal, the gap width will no longer be cut, at this time the splicing method cannot continue to be executed.

[0048] Step S8, the single crystal prepared in step S8 is washed twice with anhydrous alcohol for 5 minutes each time, and then Epoxy 301 epoxy resin is used for gap pouring, and the single crystal material needs to be placed in a vacuum environment for 24 hours at room temperature.

[0049] Step S9, polish the epoxy resin on the surface of the product of step S8 to the required thickness, and then wash and dry; then, electrodes are plated on two surfaces of the sample.

[0050] Step S10, then polarize the product of step S9, and the electric field strength used for polarization of the wafer is 8kV / cm, the polarization temperature is 80℃, and the polarization time is 10min.

[0051] In summary, the present application cuts for an integer multiple of the composite material cycle, and accurately selects the cutting lower knife position, successfully solves the problem of the excess gap between the blocks in the traditional splicing process, thereby becoming a new efficient process for preparing large-area 1-3 type piezoelectric single crystal composite material.

Claims

1. A method for preparing a large-area piezoelectric single-crystal composite material, characterized in that, 3D print a potting and fixing mold; cut single crystal blocks of specified dimensions according to integer multiples of the piezoelectric phase period of the required type 1-3 piezoelectric single crystal composite material; fix the single crystal blocks on the potting and fixing mold; pour in epoxy resin, polish, and obtain the spliced ​​single crystal; cut from the edge of the spliced ​​single crystal block, with the cutting position at half the width of the blade; pour in epoxy resin, and polish and grind its surface; Electrodes are deposited and polarized to obtain a large area of ​​type 1-3 piezoelectric single crystal composite material; Specifically, the following steps are included: Step S1: Prepare a photosensitive resin 3D printing potting and fixing mold; Step S2: Orient the piezoelectric single crystal material with good uniformity to ensure that the sample can be precisely cut along the three key crystal directions [011], [100], and [011(-)] to maximize the material performance; the good uniformity means that the piezoelectric constant in the piezoelectric single crystal material fluctuates within ±100 pC / N. Step S3: During precise cutting, cut according to an integer multiple of the piezoelectric phase period of the required type 1-3 piezoelectric single crystal composite material, and clean and dry to obtain clean, dry and cut piezoelectric single crystal blocks. Step S4: Place the cleaned, dried and cut piezoelectric single crystal pieces inside the mold of step S1 and fix them in place, and press the edges tightly to reduce gaps to obtain the spliced ​​single crystal. Step S5: Use epoxy resin to bond the assembled monocrystalline structures and allow them to cure to ensure they are stable and do not fall off. Step S6: Grind the spliced ​​single crystal surface and remove the photosensitive resin 3D printing potting fixation mold to obtain a large area piezoelectric single crystal sample; Step S7: Precisely cut the fixed large-area piezoelectric single crystal sample. Start from the edge of the spliced ​​single crystal block and cut at half 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: Clean and dry the cut monocrystalline material, fill the cut gap with epoxy resin and cure it; Step S9: Grind to remove the epoxy resin from the surface of the product from step S8, then clean and dry. Step S10: Polarize the product from step S9 to finally obtain a large-area type 1-3 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 photosensitive resin 3D printing potting and fixing mold includes a splicing mold (1) with a fixed base plate and L-shaped side panels, and two rectangular block fixing plates (2); the rectangular block fixing plates (2) are respectively set on the other two sides of the splicing mold (1), forming a square storage and tightening frame with the L-shaped splicing mold (1).

3. The method for preparing a large-area piezoelectric single-crystal composite material according to claim 1, characterized in that, The epoxy resin mentioned is Epoxy301.

4. The method for preparing a large-area piezoelectric single-crystal composite material according to claim 1, characterized in that, In 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 + slit width of the required type 1-3 piezoelectric single crystal composite material.

5. The method for preparing a large-area piezoelectric single-crystal composite material according to claim 1, characterized in that, In step S4, the fixing is achieved by using paraffin wax to fix it to the fixed base plate of the mold.

6. The method for preparing a large-area piezoelectric single-crystal composite material according to claim 1, characterized in that, In step S10, the electric field strength used for polarization is 6-10 kV / cm, the polarization temperature is 60-80℃, and the polarization time is 10-15 min.

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