A spraying plane target material and its preparation method and piezoelectric sensor

Abstract

The present application relates to the technical field of target material preparation for sputtering, and provides a spray-coated planar target material, a preparation method thereof, and a piezoelectric sensor. The preparation method of the spray-coated planar target material comprises the following steps: providing a planar target material substrate; thermally spraying the target material powder onto the surface to be sprayed of the planar target material substrate to form a target material layer, and then machining to obtain a spray-coated planar target material; wherein the surface to be sprayed includes a slope structure whose horizontal height gradually decreases from the center to the periphery. The preparation method provided in the present application adopts a thermal spraying method, which does not require long-term high-temperature sintering, and is beneficial to reducing energy consumption, costs, and improving production efficiency. In addition, the slope structure of the planar target material substrate compensates for the warping caused by the thermal stress of the target material layer, improves the surface flatness of the target material layer of the planar target, and is beneficial to improving the sputtering uniformity when it is used as a sputtering target.

Description

Technical Field

[0001] The present application belongs to the technical field of target material preparation for sputtering, and in particular relates to a sprayed planar target material, a preparation method thereof, and a piezoelectric sensor. Background Art

[0002] Lead zirconate titanate (PZT) is widely used in piezoelectric sensors, micro-actuators, memory, optical integration, optical waveguides, pyroelectric infrared detectors and micro-machines due to its excellent piezoelectric, pyroelectric, ferroelectric, nonlinear photoelectric and high dielectric properties. At present, PZT thin films are mainly prepared by sol-gel, metal organic chemical vapor deposition (MOCVD), magnetron sputtering and pulsed laser deposition (PLD). Among them, magnetron sputtering has the advantages of low deposition temperature, high efficiency, uniform and dense film formation and good adhesion, making it one of the main methods for large-scale thin film preparation.

[0003] Magnetron sputtering targets can be roughly divided into planar targets and rotating targets according to their shapes. Although rotating targets have a higher utilization rate, PZT targets tend to be insulated and cannot be coated with DC and medium frequency sputtering power supplies, so they can only be coated with RF sputtering power supplies. However, there is currently no suitable RF sputtering power supply for coating rotating targets, so PZT materials are more suitable for making planar targets.

[0004] At present, PZT planar targets are mainly prepared by a pressing and sintering process, that is, PZT powder is pressed into a green body, and then formed by high-temperature sintering. However, in order to increase the density of the target material, a long sintering time is required, which makes the production cycle too long. In addition, a high-temperature environment needs to be maintained during the sintering process, which consumes a lot of energy, which will undoubtedly increase production costs. In addition, if in order to overcome the above problems, the technical solution adopts a spraying process for preparation, due to the stress between the target ingot and the flat backing plate, it is easy to cause the produced planar target material to deform, and even cause the target ingot and the flat backing plate to delaminate. Summary of the invention

[0005] The purpose of the present application is to provide a spraying planar target material and a preparation method thereof and a piezoelectric sensor, aiming to solve the problems of long production cycle and high energy consumption in the existing preparation method of PZT planar target material.

[0006] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:

[0007] In a first aspect, the present application provides a method for preparing a spraying planar target, characterized in that it comprises the following steps:

[0008] Providing a planar target substrate;

[0009] Thermally spraying the target material powder onto the to-be-sprayed surface of the planar target material substrate to form a target material layer, and then machining to obtain a sprayed planar target material;

[0010] Wherein, the surface to be sprayed includes a slope structure whose horizontal height gradually decreases from the center to the periphery.

[0011] Optionally, the target material powder includes lead zirconate titanate granulated powder and mixed granulated powder in a mass ratio of (70-90) / (10-30), and the mixed granulated powder includes lead zirconate titanate and lead oxide.

[0012] Optionally, at least one of the following conditions is met:

[0013] The particle size of the lead zirconate titanate granulated powder is 50-120 μm;

[0014] The steps of preparing the lead zirconate titanate granulated powder include: mixing the first lead zirconate titanate raw material powder, the first dispersant and the solvent by ball milling, then adding a binder and mixing evenly, and then spraying and granulating to obtain the lead zirconate titanate granulated powder;

[0015] The particle size of the mixed granulated powder is 50-120 μm;

[0016] The steps of preparing the mixed granulated powder include: ball-milling a second lead zirconate titanate raw material powder, lead oxide powder, a second dispersant and a solvent, then adding a binder and mixing them evenly, and then spraying granulating to obtain a mixed granulated powder; the mass ratio of the second lead zirconate titanate raw material powder to the lead oxide powder is (50-60) / (40-50).

[0017] Optionally, the step of preparing the first lead zirconate titanate raw material powder includes:

[0018] According to the mass ratio of lead source, zirconium source and titanium source being (6-7) / (1.7-1.9) / (1.0-1.2), the lead source, the zirconium source, the titanium source and the third dispersant are ball-milled and mixed, and then sintered at 800-1000° C. for 6-12 hours to obtain a first lead zirconate titanate raw material powder with a particle size of 0.8-3 μm.

[0019] Optionally, at least one of the following conditions is met:

[0020] The step of preparing the second lead zirconate titanate raw material powder comprises: weighing an appropriate amount of the first lead zirconate titanate raw material powder and subjecting it to ball milling to obtain a second lead zirconate titanate raw material powder with a particle size of 300-800 nm;

[0021] The particle size of the lead oxide powder is 3-5 μm;

[0022] The amount of the third dispersant added is 0.1-1% of the total mass of the lead source, the zirconium source and the titanium source;

[0023] The lead source is selected from lead oxide, the zirconium source is selected from zirconium oxide, and the titanium source is selected from titanium oxide.

[0024] Optionally, at least one of the following conditions is met:

[0025] (1) On the surface to be sprayed, a plurality of tensile structures are sequentially arranged along the slope direction of the slope structure, and the tensile structures include grooves and / or steps intersecting with the straight line in the slope direction;

[0026] (2) The surface to be sprayed includes a conical surface or an arched surface; when the surface to be sprayed is a conical surface, the tensile structure is an annular structure, and a plurality of the tensile structures are arranged concentrically in sequence about the axis of the conical surface;

[0027] (3) The slope of the slope structure is 1° to 5°;

[0028] (4) The planar target substrate is a metal substrate.

[0029] Optionally, the thermal spraying is plasma spraying, and the plasma spraying includes:

[0030] A high-temperature plasma jet is formed by using a carrier gas, and the target material powder is introduced into the high-temperature plasma jet and sprayed out with a spray gun. The spray gun moves back and forth in a zigzag route from one side to the other side of the surface to be sprayed of the planar target material substrate to spray the target material powder onto the surface to be sprayed of the planar target material substrate.

[0031] Optionally, during plasma spraying, a shielding plate is provided on the planar target substrate, and a through hole is provided on the shielding plate at a position corresponding to the surface to be sprayed, and / or

[0032] A baffle is arranged around the outer periphery of the spray gun.

[0033] In a second aspect, the present application provides a spraying planar target material, which is prepared using the preparation method described above.

[0034] In a third aspect, the present application provides a piezoelectric sensor comprising a lead zirconate titanate layer, wherein the lead zirconate titanate layer is obtained by sputtering the sprayed flat target material as described above.

[0035] Compared with the prior art, this application has the following beneficial effects:

[0036] The method for preparing a spray-coated flat target provided in the first aspect of the present application adopts a thermal spraying method to evenly spray the target powder onto the surface to be sprayed of the target substrate, thereby integrally forming a flat target with good uniformity of organizational composition and density, thereby avoiding long-term high-temperature sintering, which is beneficial to reducing energy consumption, costs and improving production efficiency.

[0037] Furthermore, during the cooling process of the target material powder to form a target material layer by thermal spraying, the thermal stress shrinkage of the target material powder will cause deformation of the target material layer and the target material substrate, which is specifically manifested as a slight upward warping of the periphery of the planar target material as a whole, forming a structure with a high periphery and a low middle, affecting its sputtering uniformity as a sputtering target. To solve this technical problem, in the preparation method provided in the present application, before thermal spraying, the to-be-sprayed surface of the target material substrate is processed into a slope structure with a gradually decreasing horizontal height from the center to the periphery, so that the warping caused by the thermal stress of the target material layer can be compensated by the slope structure of the planar target material substrate, and the two offset each other, thereby improving the thickness uniformity of the target material layer of the planar target, thereby helping to improve the thickness uniformity of the target material coating.

[0038] The spraying planar target provided in the second aspect of the present application is prepared by the preparation method as described above, and has the characteristics of high uniformity of organizational composition, density and thickness at each position.

[0039] The piezoelectric sensor provided in the third aspect of the present application adopts the preparation method as described above to prepare a planar target material for preparing a lead zirconate titanate layer. Since the structural composition, density and thickness uniformity of the planar target material are high, it is beneficial to improve the sputtering uniformity of the lead zirconate titanate layer in the piezoelectric sensor and ensure its piezoelectric performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 is a process flow chart of a method for preparing a spray-coated flat target provided in an embodiment of the present application;

[0042] Figure 2 It is a schematic diagram of the movement trajectory of a plasma spraying gun on a surface to be sprayed provided in one embodiment of the present application;

[0043] Figure 3 is a schematic structural diagram of a shielding plate provided in one embodiment of the present application;

[0044] Figure 4 is a top view of a planar target provided in one embodiment of the present application;

[0045] Figure 5 is a cross-sectional schematic diagram of a target material substrate provided in one embodiment of the present application;

[0046] Figure 6is a cross-sectional schematic diagram of a target material substrate provided by another embodiment of the present application;

[0047] Figure 7 yes Figure 6 Enlarged view of point A in the middle;

[0048] Figure 8 This is a diagram of the state of a planar target substrate after thermal spraying provided by an embodiment of the present application.

[0049] Fig. 9 This is a diagram of the state of the planar target substrate of the present application after thermal spraying and flattening treatment.

[0050] Among them, the reference numerals in the figure are:

[0051] 1. Plane target substrate; 2. Surface to be sprayed; 3. Groove; 4. Step; 5. Angle; 6. Lower cone; 7. Target layer; 8. Shielding plate; a. Center thickness of target; b. Edge thickness of target; c. Slope. DETAILED DESCRIPTION

[0052] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0053] The first aspect of the present application provides a method for preparing a spray-coated flat target material, such as Figure 1 As shown, the following steps are included:

[0054] S1: providing a planar target substrate 1;

[0055] S2: thermally spraying the target material powder onto the to-be-sprayed surface of the planar target material substrate to form a target material layer 7, and then machining to obtain a sprayed planar target material;

[0056] The surface to be sprayed includes a slope structure whose horizontal height gradually decreases from the center to the periphery.

[0057] The method for preparing a spray-coated flat target provided in the embodiment of the present application adopts a thermal spraying method to evenly spray the target powder onto the surface to be sprayed of the target substrate, so as to obtain a flat target with good uniformity of organizational composition and density by one-piece molding, thereby avoiding long-term high-temperature sintering, which is beneficial to reducing energy consumption, cost and improving production efficiency.

[0058] During the cooling process of the target material layer 7 formed by thermal spraying, the thermal stress shrinkage of the target material powder will cause deformation of the target material layer 7 and the planar target material substrate 1, which is specifically manifested as a slight upward warping of the periphery of the planar target, forming a structure with a high periphery and a low middle, affecting its sputtering uniformity as a sputtering target. To solve this technical problem, in the preparation method provided by the present application, before thermal spraying, the surface 2 to be sprayed is processed into a slope structure with a gradually decreasing horizontal height from the center to the periphery, so that the warping caused by the thermal stress of the target material layer 7 can be compensated by the slope structure of the planar target material substrate 1, and the two can offset each other, thereby improving the thickness uniformity of the target material layer 7 of the planar target, thereby helping to improve the thickness uniformity of the target material coating.

[0059] In an embodiment, in step S2, the target powder includes lead zirconate titanate granulated powder and mixed granulated powder in a mass ratio of (70-90) / (10-30), and the mixed granulated powder includes lead zirconate titanate and lead oxide.

[0060] It should be noted that the use of lead zirconate titanate granulated powder and mixed granulated powder is based on the purpose of preparing lead zirconate titanate target materials. When preparing other similar target materials, the lead zirconate titanate granulated powder and mixed granulated powder can be replaced by corresponding target material powders.

[0061] In the embodiment, the particle size of the lead zirconate titanate granulated powder is 50-120 μm; the particle size of the mixed granulated powder is 50-120 μm. When the thermal spraying method is adopted, the particle size of the lead zirconate titanate granulated powder and the mixed granulated powder is related to the uniformity and density of the formed target layer 7. When the particle size of the lead zirconate titanate granulated powder is within the above range, it is beneficial to improve the density and uniformity of the prepared target layer 7.

[0062] In an embodiment, the step of preparing lead zirconate titanate granulated powder includes: ball milling and mixing the first lead zirconate titanate raw material powder, the first dispersant and the solvent, then adding the binder and mixing evenly, and then spray granulating to obtain the lead zirconate titanate granulated powder. Among them, the first dispersant is selected from polyethylene glycol, and its addition amount is 0.1~1% of the mass of the first lead zirconate titanate raw material powder; the binder is selected from polyvinyl alcohol, and its addition amount is 0.1~1% of the mass of the first lead zirconate titanate raw material powder; the solvent is selected from ethanol. By ball milling and mixing the lead zirconate titanate raw material powder and the first dispersant, and granulating by spray granulation, it is beneficial to fully disperse the lead zirconate titanate raw material, and obtain micron-sized lead zirconate titanate granulated powder with good particle size uniformity and fluidity, which meets the preparation requirements of thermal spraying and improves the uniformity of the thermal spraying target layer 7.

[0063] In an embodiment, the step of preparing a mixed granulated powder includes: ball milling and mixing the second lead zirconate titanate raw material powder, lead oxide powder, a second dispersant and a solvent, then adding a binder to mix evenly, and then spray granulating to obtain a mixed granulated powder. Among them, the second dispersant is selected from polyethylene glycol, and its addition amount is 0.1-1% of the total mass of the second lead zirconate titanate raw material powder and the lead oxide powder. The binder is selected from polyvinyl alcohol, and its addition amount is 0.1-1% of the total mass of the second lead zirconate titanate raw material powder and the lead oxide powder; the solvent is selected from ethanol. By ball milling and mixing the second lead zirconate titanate raw material powder, the lead oxide powder and the first dispersant, and granulating by spray granulation, the lead zirconate titanate raw material and the lead oxide powder are mixed evenly, and a mixed granulated powder with good particle size uniformity and fluidity is obtained, which meets the process requirements of thermal spraying and improves the uniformity of the thermal spraying target layer 7.

[0064] In the embodiment, the mass ratio of the second lead zirconate titanate raw material powder and the lead oxide powder is (50~60) / (40~50). If the lead oxide powder is too little, the powder bonding effect after spraying is poor, it is difficult to form a dense target material, and the powder deposition rate is low. If the lead oxide powder is too much, it is difficult to ensure the uniformity of the organizational composition of the prepared target material. Therefore, within this mass ratio range, a uniform and dense sprayed flat target material can be obtained, and the powder deposition rate is relatively high.

[0065] In an embodiment, the step of preparing the first lead zirconate titanate raw material powder comprises: ball milling and mixing the lead source, zirconium source, titanium source and the third dispersant according to the mass ratio of the lead source, zirconium source and titanium source of (6-7) / (1.7-1.9) / (1.0-1.2), and then sintering at 800-1000°C for 6-12h to obtain the first lead zirconate titanate raw material powder with a particle size of 0.8-3μm. Among them, the lead source is selected from lead oxide, the zirconium source is selected from zirconium oxide, and the titanium source is selected from titanium oxide. The third dispersant is selected from polycarboxylate dispersants, and preferably, the second dispersant includes one or more of polycarboxylate ammonium salt, polyacrylic acid, and sodium polyacrylate, and the addition amount thereof is 0.1-1% of the total mass of the lead source, zirconium source and titanium source.

[0066] In an embodiment, the step of preparing the second lead zirconate titanate raw material powder comprises: weighing an appropriate amount of the first lead zirconate titanate raw material powder and performing ball milling to obtain the second lead zirconate titanate raw material powder with a particle size of 300-800 nm.

[0067] In the embodiment, the particle size of the lead oxide powder is 3-5 μm. In this particle size range, the second lead zirconate titanate raw material powder with a particle size of 300-800 nm is conducive to adhering to the surface of the lead oxide powder during the ball milling process, so that the mixed granulated powder obtained by spray granulation can infiltrate the lead zirconate titanate during thermal spraying to play a bonding role, thereby improving the density of the prepared target material and the deposition rate of the powder.

[0068] During the cooling process after spraying, the target powder will produce thermal stress contraction. When the target substrate is tubular, it can balance the tensile stress of the target layer in each radial direction during the contraction process (the components of the tensile stress along the diameter direction can offset each other). Therefore, the existing thermal spray process is usually used to prepare rotating targets. However, when the target substrate is a plane, due to the stress between the target layer and the plane substrate, it is easy to cause serious deformation of the plane target, and even cause the problem of delamination between the target layer and the plane substrate. To solve this problem, the present application sets the spraying surface of the plane target substrate as a slope structure with a gradually decreasing horizontal height from the center to the periphery to balance the deformation problem caused by stress. Furthermore, the present application sets a tensile structure on the slope structure to improve the bonding strength between the target layer and the plane target substrate to avoid the problem of the target layer falling off.

[0069] Specifically, Figure 5~Figure 7 As shown, in the embodiment, in step S1, a plurality of tensile structures are sequentially arranged on the surface 2 to be sprayed along the slope direction of the slope structure, and the tensile structures include grooves 3 and / or steps 4 intersecting with the straight line in the slope direction.

[0070] Since the thermal stress generated by the target material layer 7 during the cooling process will directly act on the planar target material substrate 1, thereby affecting the bonding strength between the target material layer 7 and the planar target material substrate 1, and in severe cases, pulling and delamination may be caused. By providing a plurality of grooves 3 and / or steps 4 as a tensile structure, a structure similar to a clamping joint can be formed between the target material layer 7 and the planar target material substrate 1 in addition to the surface bonding force, which is beneficial to improving the bonding strength between the target material layer 7 and the planar target material substrate 1 and avoiding the delamination problem of the target material layer 7.

[0071] like Figure 5 As shown, in the embodiment, the depth of the groove 3 is 0.1-0.3 cm, the width is 0.2-1 cm, and the distance between adjacent grooves 3 is 2-5 cm.

[0072] The size of the groove 3 affects the bonding between the target layer 7 and the planar target substrate 1. If the depth of the groove 3 is too large, it will easily affect the surface flatness of the target layer 7; if the depth of the groove 3 is too small, it will affect the bonding strength between the target layer 7 and the planar target substrate 1.

[0073] When the width and the spacing of the grooves 3 are within the above ranges, it is beneficial to improve the consistency of the bonding strength between the target layer 7 and the planar target substrate 1 at different positions.

[0074] like Figure 6 and Figure 7As shown, in the embodiment, the step 4 includes vertical walls and bottom surfaces connected alternately in sequence, and the included angle 5 between the vertical wall and the bottom surface connected to the bottom edge of the vertical wall is 90° to 150°. Preferably, the included angle 5 between the vertical wall and the bottom surface is equal to 90°.

[0075] In the embodiment, the height of the vertical wall is 0.05-0.1 cm, and the distance between adjacent vertical walls is 2-20 cm.

[0076] The functions of the vertical wall and the groove 3 are similar. If the height of the vertical wall is too large, it will easily affect the surface flatness of the target layer 7; if the height of the vertical wall is too small, it will affect the bonding strength between the target layer 7 and the planar target substrate 1.

[0077] In an embodiment, the surface 2 to be sprayed includes a conical surface or an arcuate surface.

[0078] In the embodiment, the planar target substrate 1 is a disk-like structure, and the surface to be sprayed 2 is a cone-like structure formed with the planar target substrate 1 .

[0079] When the shape of the surface 2 to be sprayed is circular, the plane target tends to form a warping of an inverted cone structure when the target layer 7 shrinks due to thermal stress. Therefore, setting the surface 2 to be sprayed as a conical surface is beneficial to offset the warping of the inverted cone structure formed by the plane target. Correspondingly, when the shape of the surface 2 to be sprayed is a strip or a rectangle, the plane target tends to form a warping of a U-shaped structure. At this time, setting the surface 2 to be sprayed as an arched surface can adapt to the warping of the U-shaped structure to obtain a flat surface of the target layer 7.

[0080] In the embodiment, when the surface 2 to be sprayed is a conical surface, the tensile structure is an annular structure, and a plurality of tensile structures are arranged concentrically in sequence about the axis of the conical surface.

[0081] It should be noted that the setting of the tensile structure itself will also affect the stress distribution between the target layer 7 and the planar target substrate 1. Therefore, setting a symmetrical tensile structure is more conducive to ensuring the force balance at various positions of the planar target. The symmetry of the tensile structure is based on the specific shape of the surface 2 to be sprayed. When the surface 2 to be sprayed is a conical surface, a ring-shaped tensile structure surrounding the axis of the cone is set, which is conducive to ensuring the stress balance at various positions of the cone due to the setting of the tensile structure, and avoiding deformation of the planar target due to the setting of the tensile structure.

[0082] In the description of this application, the term "slope" refers to the degree of inclination of the slope structure, specifically the angle between the slope structure and the horizontal plane (the horizontal plane is defined by the surface of the flat target substrate 1 facing away from the target layer 7 before thermal spraying). Specifically, the slope of the slope structure is as follows: Figure 5 As shown in the middle angle c.

[0083] In the embodiment, the slope of the slope structure is used to balance the warping caused by the thermal shrinkage stress of the material layer, and needs to be determined according to the thermal expansion coefficient of the target powder selected in the thermal spraying and the planar target substrate 1. Under normal circumstances, since the warping amplitude caused by the thermal shrinkage stress of the target layer 7 is generally low, the slope of the slope structure should be set as low as possible. In a preferred embodiment, the slope of the slope structure is 1°~5° to avoid the reverse warping of the planar target due to the excessive slope of the slope structure.

[0084] In the embodiment, the planar target substrate 1 is a metal substrate.

[0085] In a preferred embodiment, the planar target substrate 1 comprises one or more of copper, titanium or stainless steel.

[0086] When the planar target substrate 1 is selected from the above metal materials, it has the characteristics of low processing difficulty and high material strength, can provide a good support effect for the target layer 7, and at the same time meet the processing requirements for the slope structure and tensile structure on the planar target substrate 1 in this application.

[0087] In an embodiment, in step S2, thermal spraying includes one or more of plasma spraying, flame spraying, and arc spraying.

[0088] In an embodiment, the thermal spraying method is plasma spraying, and the plasma spraying includes the following steps:

[0089] A high-temperature plasma jet is formed by using a carrier gas, and the target powder is introduced into the high-temperature plasma jet and sprayed out with the spray gun. The spray gun moves back and forth in a zigzag route from one side to the other side of the surface 2 to be sprayed of the flat target substrate 1. The walking trajectory is as follows Figure 2 As shown, the target material powder is sprayed onto the to-be-sprayed surface 2 of the planar target material substrate 1 .

[0090] By moving the spray gun back and forth in a zigzag route, the target material powder can cover the entire surface of the surface 2 to be sprayed. At the same time, since the repetition rate of the spray gun's movement path on the surface 2 to be sprayed is consistent, it is beneficial to ensure the consistency of the thickness of the target material layer 7 sprayed to each position of the surface 2 to be sprayed.

[0091] In an embodiment, the carrier gas includes Ar, N2 or other inert gases.

[0092] In the embodiment, the distance between the spray gun and the planar target substrate 1 is 90-110 mm, the powder feeding amount is 150-250 g / min, and the moving speed is 30-60 mm / min.

[0093] In the embodiment, when plasma spraying is performed, a shielding plate 8 is provided on the planar target substrate 1, and the shielding plate 8 has a structure as shown in FIG. Figure 3As shown, a through hole is opened on the shielding plate 8 at a position corresponding to the surface 2 to be sprayed, and the shape of the through hole is consistent with the shape of the surface 2 to be sprayed. The target material layer 7 obtained is as shown in FIG. Figure 4 shown.

[0094] By providing the shielding plate 8, the non-sprayed surface on the planar target substrate 1 can be protected to prevent the target powder from being sprayed onto the edge of the planar target substrate 1, thereby reducing the difficulty of post-processing and shortening the process flow.

[0095] In an embodiment, a baffle is arranged around the outer periphery of the spray gun.

[0096] Preferably, the baffle is annular and fixed to the outer periphery of the spray gun. The baffle moves with the spray gun during the spraying process to prevent the target material powder sprayed from the spray gun from splashing, thereby improving the utilization rate of the target material powder.

[0097] In an embodiment, in step S2 , the machining operation includes: performing a planarization process on the surface of the planar target substrate 1 that is away from the target layer 7 .

[0098] like Figure 8 As shown, after the thermal spraying is completed, due to the thermal shrinkage stress of the target layer 7, the periphery of the planar target substrate 1 will be warped upward to a certain extent, resulting in a certain downward taper 6 on the surface of the planar target substrate 1 away from the target layer 7. The downward taper 6 on the surface of the planar target substrate 1 away from the target layer 7 is removed by flattening treatment to ensure the flatness of the surface of the planar target substrate 1 away from the target layer 7. The planar target structure after the flattening treatment is as shown in FIG. Fig. 9 shown.

[0099] In an embodiment, the planarization process includes one or more of turning, planing, grinding, and sandblasting.

[0100] In the embodiment, before thermal spraying, step S1 performs the following operations on the spraying surface 2:

[0101] The surface 2 to be sprayed is subjected to sandblasting to roughen the surface 2 to be sprayed.

[0102] By performing sandblasting, the surface to be sprayed 2 can be roughened, which can significantly enhance the adhesion and mechanical locking effect between the target layer 7 and the planar target substrate 1, and prevent the target layer 7 from falling off due to stress.

[0103] In an embodiment, the sandblasting process uses one or more of white corundum and brown corundum.

[0104] In the embodiment, before thermal spraying, step S1 performs the following operations on the spraying surface 2:

[0105] The self-fluxing alloy arc priming is performed on the surface 2 to be sprayed.

[0106] Specifically, the self-fluxing alloy arc primer uses alloy material as raw material, utilizes the high temperature generated by the arc to melt the alloy material, and deposits it on the surface of the to-be-sprayed surface 2 to form a coating.

[0107] The alloy material is selected from a self-fluxing alloy material, that is, it can melt by itself and combine with the substrate under the action of the electric arc without the need for additional flux.

[0108] In an embodiment, the alloy material is selected from copper-aluminum alloy or nickel-aluminum alloy.

[0109] When the alloy material is selected from the above materials, on the one hand, it has a higher affinity with the planar target substrate 1 made of metal material, and on the other hand, it can also improve the bonding strength with the target layer 7, playing a role of stress buffering between the planar target substrate 1 and the target layer 7.

[0110] In an embodiment, the diameter of the sprayed flat target is 100-600 cm.

[0111] In the second aspect, the present application provides a spraying flat target material, which is prepared by the above preparation method and has the characteristics of high uniformity of organizational composition, density and thickness at each position.

[0112] In a third aspect, the present application provides a piezoelectric sensor, comprising a lead zirconate titanate layer, wherein the lead zirconate titanate layer is obtained by sputtering a planar target, and the planar target is prepared by the above preparation method.

[0113] The piezoelectric sensor uses the above preparation method to prepare a planar target material for preparing a lead zirconate titanate layer. Since the structure, density and thickness uniformity of the planar target material are high, it is beneficial to improve the sputtering uniformity of the lead zirconate titanate layer in the piezoelectric sensor and ensure its piezoelectric performance.

[0114] The technical solution of the present application is further described below in conjunction with specific embodiments.

[0115] Example 1

[0116] This embodiment is used to illustrate the method for preparing a spraying planar target provided by the present application, and comprises the following steps:

[0117] 1. Prepare a copper substrate of φ500*8mm.

[0118] 2. Process the top of the flat circular metal substrate into a cone, ab=3mm, a is the center thickness of the target, b is the edge thickness of the target, and the slope of the cone is 3°.

[0119] 3. Open multiple Figure 5The annular groove of the shape shown is 3 mm wide and 0.5 mm deep, obtaining a flat target substrate, and the conical surface is used as the surface to be sprayed.

[0120] 4. The surface to be sprayed is sandblasted. The sand is selected from 60-mesh brown corundum. Since copper has a low hardness, the sandblasting pressure can be controlled at 3 kgf.

[0121] 5. Use copper-aluminum wire arc to form a base layer on the surface to be sprayed. The base layer thickness is about 0.3mm to obtain a flat target substrate.

[0122] 6. According to the mass ratio of lead oxide, zirconium oxide and titanium oxide of 6.5 / 1.8 / 1.1, lead oxide, zirconium oxide, titanium oxide and polycarboxylate ammonium salt are ball-milled and mixed, and then sintered at 1000° C. for 8 hours to obtain a first lead zirconate titanate raw material powder with an average particle size of 1.5 μm;

[0123] Part of the first lead zirconate titanate raw material powder is mixed with polyethylene glycol and ethanol by ball milling, then polyvinyl alcohol is added and mixed, and then spray granulation is performed to obtain lead zirconate titanate granulated powder with a particle size of 70-100 μm; the amount of polyethylene glycol added is 0.5% of the mass of the first lead zirconate titanate raw material powder, and the amount of polyvinyl alcohol added is 0.5% of the mass of the first lead zirconate titanate raw material powder;

[0124] An appropriate amount of the first lead zirconate titanate raw material powder is ball-milled to an average particle size of 500 nm to obtain a second lead zirconate titanate raw material powder; the second lead zirconate titanate raw material powder, lead oxide powder (average particle size of 4 μm), polyethylene glycol and ethanol are ball-milled and mixed, polyvinyl alcohol is then added and mixed, and then spray granulation is performed to obtain a mixed granulated powder with a particle size of 70 to 100 μm; the mass ratio of the second lead zirconate titanate raw material powder to the lead oxide powder is 55 / 45; the amount of polyethylene glycol added is 0.5% of the total mass of the second lead zirconate titanate raw material powder and the lead oxide powder, and the amount of polyvinyl alcohol added is 0.5% of the total mass of the second lead zirconate titanate raw material powder and the lead oxide powder;

[0125] The lead zirconate titanate granulated powder and the mixed granulated powder were mixed evenly in a mass ratio of 80 / 20, and then calcined at 550° C. for 5 hours to obtain a target material powder.

[0126] 7. Use plasma spraying equipment to spray the target powder onto the surface of the flat target substrate to be sprayed. Specifically, program the spray gun to move back and forth in a zigzag route from one side to the other side of the surface of the flat target substrate to be sprayed, and spray the lead zirconate titanate granulated powder onto the surface of the flat target substrate to be sprayed one by one. When the thickness is equal to 8 mm, stop the machine and cool it to form a target layer.

[0127] 8. Polish and turn the surface and surrounding areas of the lead zirconate titanate target layer to meet size requirements.

[0128] 9. Finally, the lower cone caused by the difference in thermal expansion coefficient between the planar target substrate and the target layer is flattened.

[0129] Example 2

[0130] This example is used to illustrate the method for preparing a spray-coated flat target provided by the present application, and includes most of the steps in Example 1, except that:

[0131] In step 3, multiple Figure 6 The steps of the shape shown include vertical walls and bottom surfaces connected alternately in sequence, the height of the vertical walls is 0.07 cm, and the distance between adjacent vertical walls is 8 cm; a flat target material substrate is obtained, and the conical surface is used as the surface to be sprayed.

[0132] Example 3

[0133] This example is used to illustrate the method for preparing a spray-coated flat target provided by the present application, and includes most of the steps in Example 1, except that:

[0134] The operation of step 3 is not performed, and the structure of step 2 is directly used as the planar target substrate, and the conical surface is used as the surface to be sprayed.

[0135] Comparative Example 1

[0136] This comparative example provides a method for preparing a spray-coated flat target material, which differs from Example 1 in that:

[0137] Step 6: According to the mass ratio of lead oxide, zirconium oxide and titanium oxide of 6.5 / 1.8 / 1.1, lead oxide, zirconium oxide, titanium oxide and polycarboxylate ammonium salt are ball-milled and mixed, and then sintered at 1000° C. for 8 hours to obtain a first lead zirconate titanate raw material powder with an average particle size of 1.5 μm;

[0138] The first lead zirconate titanate raw material powder is mixed with polyethylene glycol and ethanol by ball milling, and then polyvinyl alcohol is added and mixed, and then spray granulation is performed to obtain lead zirconate titanate granulated powder with a particle size of 70-100 μm (as target material powder); the amount of polyethylene glycol added is 0.5% of the mass of the first lead zirconate titanate raw material powder, and the amount of polyvinyl alcohol added is 0.5% of the mass of the first lead zirconate titanate raw material powder.

[0139] Comparative Example 2

[0140] This example is used to illustrate the method for preparing a spray-coated flat target provided by the present application, and includes most of the steps in Example 1, except that:

[0141] The operation of step 2 is not performed, the top surface of the copper substrate is a plane, and an annular groove is opened on the top surface of the copper substrate at the position corresponding to Example 1 in step 3. The groove is 3 mm wide and 0.5 mm deep, and the top surface of the copper substrate is used as the surface to be sprayed.

[0142] Comparative Example 3

[0143] This example is used to illustrate the method for preparing a spraying planar target provided by the present application, and includes most of the operation steps in Example 1, except that:

[0144] Without performing the operations of step 2 and step 3, the copper substrate is directly used as the planar target substrate, and the top surface of the copper substrate is used as the surface to be sprayed.

[0145] Related performance test analysis:

[0146] 1. The following tests were performed on the spraying planar targets prepared in Example 1 and Comparative Example 1:

[0147] 1) After the sprayed flat target is plastic-sealed, its actual density is tested using the Archimedes density test method. Based on the theoretical density, the relative density of each block is calculated;

[0148] 2) Deposition rate = weight of target layer / weight of target powder × 100%.

[0149] The test results are shown in Table 1 below:

[0150] Table 1

[0151]

[0152] It can be seen from Table 1 that the relative density and deposition rate of the sprayed flat target prepared in Example 1 are higher than those in Comparative Example 1, indicating that in the embodiment of the present application, by adding part of the lead oxide powder and mixing with lead zirconate titanate for spray granulation, the lead oxide powder in the obtained mixed granulated powder plays a bonding role during the spraying process, thereby improving the deposition rate of the powder and the relative density of the target.

[0153] 2. The following tests were performed on the planar targets prepared in Examples 1 to 3 and Comparative Examples 2 to 3:

[0154] 1) Use a surface profiler to move the scanning probe on the target layer and record the height change of the probe relative to the reference surface to obtain surface profile information; the difference between the lowest and highest height values ​​of the target layer is taken as the height range;

[0155] 2) Use a tool to draw a grid on the surface of the target layer, use tape to attach to the grid, and then tear off the tape to check the coating shedding to evaluate the bonding strength. The evaluation grades are 5B (best), 4B, 3B, 2B, and 1B, where 5B means the target layer has not fallen off at all; 1B means the target layer has fallen off completely.

[0156] The test results are shown in Table 2 below:

[0157] Table 2

[0158]

[0159] As can be seen from Table 2, the height extreme difference of Examples 1 to 3 is significantly smaller than that of Comparative Examples 2 and 3, indicating that the embodiment of the present application can effectively balance the stress warping problem caused by the plasma sprayed lead zirconate titanate granulated powder during the cooling process by setting a slope structure on the planar target substrate, thereby ensuring the surface flatness of the prepared planar target. The bonding strength of Examples 1 to 2 is better than that of Example 3, indicating that the embodiment of the present application further sets an annular groove or a step structure on the slope structure as a tensile structure, which can further enhance the bonding strength between the target layer and the planar target substrate and avoid the problem of the target layer falling off.

[0160] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a spraying planar target, characterized in that: The following steps are involved: Providing a planar target substrate; Thermally spraying the target material powder onto the to-be-sprayed surface of the planar target material substrate to form a target material layer, and then machining to obtain a sprayed planar target material; Among them, the surface to be sprayed includes a slope structure with a gradually decreasing horizontal height from the center to the periphery; on the surface to be sprayed, a plurality of tensile structures are arranged in sequence along the slope direction of the slope structure, and the tensile structure includes grooves and / or steps intersecting with the straight line in the slope direction; the slope of the slope structure is 1°~5°; the planar target material substrate is a metal substrate.

2. The preparation method according to claim 1, characterized in that The target material powder comprises lead zirconate titanate granulated powder and mixed granulated powder in a mass ratio of (70-90) / (10-30), wherein the mixed granulated powder comprises lead zirconate titanate and lead oxide.

3. The preparation method according to claim 2, characterized in that: At least one of the following conditions is met: The particle size of the lead zirconate titanate granulated powder is 50-120 μm; The steps of preparing the lead zirconate titanate granulated powder include: mixing the first lead zirconate titanate raw material powder, the first dispersant and the solvent by ball milling, then adding a binder and mixing evenly, and then spraying and granulating to obtain the lead zirconate titanate granulated powder; The particle size of the mixed granulated powder is 50-120 μm; The steps of preparing the mixed granulated powder include: ball-milling a second lead zirconate titanate raw material powder, lead oxide powder, a second dispersant and a solvent, then adding a binder and mixing them evenly, and then spraying granulating to obtain a mixed granulated powder; the mass ratio of the second lead zirconate titanate raw material powder to the lead oxide powder is (50-60) / (40-50).

4. The preparation method according to claim 3, characterized in that: The steps of preparing the first lead zirconate titanate raw material powder include: According to the mass ratio of lead source, zirconium source and titanium source being (6-7) / (1.7-1.9) / (1.0-1.2), the lead source, the zirconium source, the titanium source and the third dispersant are ball-milled and mixed, and then sintered at 800-1000° C. for 6-12 hours to obtain a first lead zirconate titanate raw material powder with a particle size of 0.8-3 μm.

5. The preparation method according to claim 4, characterized in that: At least one of the following conditions is met: The step of preparing the second lead zirconate titanate raw material powder comprises: weighing an appropriate amount of the first lead zirconate titanate raw material powder and subjecting it to ball milling to obtain a second lead zirconate titanate raw material powder with a particle size of 300-800 nm; The particle size of the lead oxide powder is 3-5 μm; The amount of the third dispersant added is 0.1-1% of the total mass of the lead source, the zirconium source and the titanium source; The lead source is selected from lead oxide, the zirconium source is selected from zirconium oxide, and the titanium source is selected from titanium oxide.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The surface to be sprayed includes a conical surface or an arched surface; when the surface to be sprayed is a conical surface, the tensile structure is an annular structure, and a plurality of the tensile structures are arranged concentrically in sequence about the axis of the conical surface.

7. The preparation method according to any one of claims 1 to 5, characterized in that The thermal spraying is plasma spraying, and the plasma spraying includes: A high-temperature plasma jet is formed by using a carrier gas, and the target material powder is introduced into the high-temperature plasma jet and sprayed out with a spray gun. The spray gun moves back and forth in a zigzag route from one side to the other side of the surface to be sprayed of the planar target material substrate to spray the target material powder onto the surface to be sprayed of the planar target material substrate.

8. The preparation method according to claim 7, characterized in that: During plasma spraying, a shielding plate is provided on the planar target substrate, and a through hole is provided on the shielding plate at a position corresponding to the surface to be sprayed, and / or A baffle is arranged around the outer periphery of the spray gun.

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