High-temperature-resistant radiation-resistant AlN-based piezoelectric coating material as well as preparation method and application thereof

Abstract

The invention discloses a high-temperature-resistant radiation-resistant AlN-based piezoelectric coating material as well as a preparation method and application thereof, and relates to the technical field of ultrasonic piezoelectric coating materials. The preparation method of the piezoelectric coating material provided by the invention comprises the step of forming an AlScCrTaTiN piezoelectric coating on the surface of a substrate by adopting an AlScCrTaTi alloy target material through magnetron sputtering. By regulating and controlling the component proportion of the AlScCrTaTi alloy target material, it is guaranteed that the prepared coating has an AlN hexagonal structure, meanwhile, the proportion of the number of doped atoms of Al in the target material is not lower than 70%, and the component proportion of Sc, Cr, Ta and Ti is not lower than 5%; by controlling the volume ratio of argon to nitrogen, the temperature, the sputtering power, the deposition air pressure and the target-substrate distance in magnetron sputtering, the prepared AlN-based piezoelectric coating material has good mechanical properties, temperature resistance, corrosion resistance and radiation resistance, and provides guarantee for safe operation of advanced nuclear power gateways.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic piezoelectric coating materials, and in particular to a high-temperature and radiation-resistant AlN-based piezoelectric coating material, a preparation method thereof, and applications thereof. Background Art

[0002] As a sustainable, clean energy source, nuclear power's development hinges on the safety and economic viability of its operations. The long-term reliability and stability of key structural materials in nuclear power plants under high-temperature, high-pressure water and irradiation environments are crucial factors influencing their safety and economic viability. The nuclear power reactors currently under construction and operation in my country are primarily pressurized water reactors (PWRs). Commonly used structural materials include nickel-based 690 alloy and its weld metal, nickel-based 52 / 152 alloys, 304 and 316 austenitic stainless steels, low-alloy steel, 800 alloy, and carbon steel. These materials operate in flowing, high-temperature, high-pressure water, subjecting them to complex operating stresses. Materials in the core are also subject to intense irradiation, significantly increasing their susceptibility to environmental damage.

[0003] Among the above-mentioned environmental damages, stress corrosion cracking (SCC) is the main cause of material failure of welded joints and steam generator heat transfer tubes in pressurized water reactors. Since nuclear reactor pressure vessels are large in size and cannot be accessed during in-service inspections, ultrasonic automated testing technology is usually used when conducting ultrasonic inspections of nuclear reactor pressure vessels. That is, a dedicated reactor pressure vessel inspection machine is used to drive the ultrasonic detection probe to automatically scan the inspected area. The entire ultrasonic inspection is carried out from the inner surface of the pressure vessel. The inspection adopts a contact inspection method between the probe and the inspected component, and water is used for coupling. This method requires the development of appropriate ultrasonic sensors to adapt to the temperature range of 160-450°C, work under very harsh conditions and be suitable for imaging purposes. Harsh conditions generally mean that the entire inspection process must be carried out at a gamma ray dose rate level of up to tens of kGy / h and a total dose of tens of MGy, as well as close to 1019 n / cm 2 The medium neutron irradiation level of thermal neutrons must be considered; the dissolution / oxidation of structural materials in liquid metal must also be considered. However, there are currently no ultrasonic transducers suitable for long-term continuous operation in a reactor environment.

[0004] Based on the above special application scenarios, piezoelectric film is also the core component of ultrasonic sensors. Therefore, the radiation resistance of piezoelectric film is a key indicator for the performance evaluation of ultrasonic sensors. In terms of existing research, Bernhard et al. (B. Tittmann, C. Batista, Y. Trivedi, C. Lissenden, B. Reinhardt. State-of-the-art and practical guide to ultrasonic transducers for harsh environmentsincluding temperatures above 2120 °F (1000 °C) and neutron flux above 1013 n / cm2[J]. Sensors, 19 (2019) 1.) exposed single crystal AlN materials to fast neutrons and thermal neutrons in a nuclear reactor core for more than 120 MWh, with a dose of up to 1.0×1020 n / cm 2 Under high temperatures, the piezoelectric coefficient d33 of AlN remains virtually unchanged, demonstrating excellent radiation resistance. Similarly, the performance of irradiated AlN crystals remains unchanged when subjected to temperatures of 950°C for 72 hours. Although materials such as LiNbO3 and AlN have demonstrated excellent radiation resistance, existing radiation performance studies are based on radiation doses used during periodic outage inspections, which are far lower than the total radiation dose experienced during the lifecycle of a nuclear power plant. This makes the reliability of these results difficult to ascertain. During nuclear power plant operation, piezoelectric film must outlast the lifespan of the probe. Therefore, it is necessary to design radiation-resistant piezoelectric film materials and study their damage at high radiation doses and their impact on detector performance. Existing research (Wenjing Qin, Feng Ren, Russell P. Doerner, Guo Wei, Yawei Lv, Sheng Chang, Ming Tang, Huiqiu Deng, Changzhong Jiang, Yongqiang Wang, “Nanochannel structures in Wenhance radiation tolerance”, Acta Materialia 153 (2018) 147) indicates that thin films with columnar crystal structures can effectively absorb radiation defects due to the free surfaces and grain boundaries of the columnar crystals, significantly improving their radiation resistance. Furthermore, previous studies (ZL202110653531 and ZL2020109040207) have shown that doping piezoelectric films with rare earth elements can effectively improve their thermal stability and piezoelectric constant.

[0005] Aluminum nitride (AlN) has a high melting temperature (approximately 2500°C) and a high Curie temperature (approximately 1150°C), allowing it to maintain its piezoelectric properties at high temperatures. However, compared to other piezoelectric materials (such as PZT), pure AlN films have a poor natural piezoelectric response. For example, research reports have shown that the out-of-plane piezoelectric strain modulus d33 of reactively sputtered AlN films is 5.5 pC / N, while the d33 value of ZnO is at least twice that, and that of lead zirconate titanate films can exceed 100 pC / N.

[0006] A common approach to engineering the piezoelectric properties of AlN is to alloy it with transition metal nitrides (e.g., Sc, Y), leading to a multifold increase in field-induced strain through an increase in the longitudinal piezoelectric coefficient e33 and a simultaneous decrease in the longitudinal elastic stiffness C33. However, increasing the alloy concentration leads to a breakdown of the piezoelectric response during the transition to the (centrosymmetric, cubic) rocksalt structure. Even when using nonequilibrium deposition processes (e.g., sputtering), experimentally achieving high alloy concentrations without severe degradation of phase separation, film texture, and crystalline quality is challenging. Therefore, it is desirable to identify alloy systems that undergo the structural transition from wurtzite to rocksalt at low alloy concentrations. Most notably, Akiyama et al. (Akiyama, Morito, et al. "Enhancement of piezoelectric response in scandium aluminum nitride alloy thinfilms prepared by dual reactive cosputtering." Advanced Materials 21.5(2009): 593-596.) found that the d33 modulus in sputtered AlN films can be increased by nearly 500% when doped with scandium (Sc). Later studies found that (Startt, J., Quazi, M., Sharma, P., Vazquez, I., Poudyal, A.,Jackson, N., & Dingreville, R. (2023). Unlocking AlN piezoelectric performance with earth-abundant dopants. Advanced Electronic Materials,9(4),2201187.) the d33 modulus in sputtered AlN films can be increased by nearly 500% when doped with scandium (Sc). Later studies found that other rare earth elements such as yttrium (Y) and ytterbium (Yb) can also induce similar piezoelectric enhancement in AlN.

[0007] However, two factors limit the integration of these dopants into commercial process flows: (1) rare earth sputtering targets (such as Sc and Yb) are expensive; and (2) the stability of the prepared films decreases with increasing dopant element concentration. Summary of the Invention

[0008] The present invention provides a high-temperature and radiation-resistant AlN-based piezoelectric coating material, its preparation method, and its application. To address the aforementioned technical challenges and needs in stress monitoring for nuclear facilities (such as nuclear reactors), the present invention utilizes several special metal elements and specific doping levels to produce an AlScCrTaTiN piezoelectric coating co-doped with four metal elements: Sc, Cr, Ta, and Ti. This coating exhibits long life, high-temperature resistance, and radiation resistance. The AlScCrTaTiN piezoelectric coating provided by the present invention provides a new approach for preparing high-performance piezoelectric devices suitable for real-time online nuclear stress detection. The present invention is implemented through the following techniques.

[0009] Based on this, a new type of radiation-resistant and high-temperature-resistant AlN-based piezoelectric coating material and its preparation method are provided, and they are applied to the manufacture of ultrasonic transducers in nuclear power plants. This is of great significance for achieving accurate and non-destructive measurement of nuclear power plants, and is also a technical problem that researchers urgently need to solve.

[0010] A first aspect of the present invention provides a method for preparing a high-temperature-resistant and radiation-resistant AlN-based piezoelectric coating material, comprising the following steps:

[0011] Using AlScCrTaTi alloy target material, an AlScCrTaTiN piezoelectric coating is formed on the surface of the substrate by magnetron sputtering method;

[0012] In the AlScCrTaTi alloy target material, the proportion of doped Al atoms is not less than 70%, and the proportion of doped Sc, Cr, Ta and Ti atoms is not less than 5%.

[0013] In the preparation method of the high-temperature and radiation-resistant AlN-based piezoelectric coating material provided by the present invention, an AlScCrTaTiN piezoelectric coating is prepared using radio frequency magnetron sputtering technology. Controlling the sputtering temperature within the range of 60-250°C ensures that the particles have sufficient energy to migrate to the surface of the substrate and deposit the AlScCrTaTiN coating. Appropriately increasing the temperature can result in particles with higher energy. By controlling the volume ratio of argon and nitrogen, the above preparation method can control the atomic percentages of metal ions and nitrogen particles in the vacuum chamber, adjust the probability of collisions between particles, and adjust the growth orientation of the coating. The above preparation method uses a sputtering power of 500-900 W, which can adjust the energy of the particles and the thickness of the prepared coating. The above preparation method controls the deposition pressure (the pressure after the reaction gas is introduced into the vacuum chamber) to 0.6-4.0 Pa and the target-substrate spacing (the vertical distance between the target and the substrate) to 40-80 mm. This allows the mean free path of the particles to be controlled, allowing the preparation of AlScCrTaTiN piezoelectric coatings with various growth orientations within this deposition range. Under the above preparation conditions, an AlScCrTaTiN piezoelectric coating can be prepared that has high high-temperature resistance and radiation resistance and can excite a variety of ultrasonic waves.

[0014] The present invention has found that by adjusting relevant parameters in the magnetron sputtering process, such as the volume ratio of argon and nitrogen, the deposition pressure, and the target-substrate distance, the AlScCrTaTiN piezoelectric coating can exhibit multiple growth orientations on the substrate surface, thereby stimulating multiple ultrasonic waveforms. Furthermore, an AlScCrTaTiN piezoelectric coating material capable of stimulating different ultrasonic waves can be prepared according to detection requirements. The AlScCrTaTiN piezoelectric coating material provided by the present invention has a growth orientation on the substrate surface that includes one or more of the following: (002) diffraction crystal plane, (100) diffraction crystal plane, (101) diffraction crystal plane, and (102) diffraction crystal plane. The structure is the hexagonal wurtzite structure of AlN, exhibiting piezoelectric properties.

[0015] Optionally, in the preparation method of the high-temperature-resistant and radiation-resistant AlN-based piezoelectric coating material provided by the present invention, the material of the substrate includes but is not limited to stainless steel, aluminum, cemented carbide, high-speed steel, titanium and other substrates suitable for ultrasonic detection.

[0016] Furthermore, in the AlScCrTaTi alloy target, the number of doped atoms of Sc accounts for 5-10%; the number of doped atoms of Cr accounts for 5-10%; the number of doped atoms of Ta accounts for 5-10%; and the number of doped atoms of Ti accounts for 5-10%.

[0017] Furthermore, in the AlScCrTaTi alloy target, the number of doped atoms of Sc accounts for 10%, the number of doped atoms of Cr accounts for 5%, the number of doped atoms of Ta accounts for 5%, and the number of doped atoms of Ti accounts for 5%.

[0018] The preparation method of the present invention utilizes a target with a larger diameter, enabling the simultaneous preparation of more samples during the coating deposition process (i.e., finished products after AlN-based piezoelectric coatings are deposited on substrates of different materials). This method offers higher deposition efficiency, facilitates mass production, and is more readily applicable for widespread use. Furthermore, the AlScCrTaTi alloy target has a diameter of 100-160 mm and a thickness of 4-8 mm.

[0019] Furthermore, the substrate is subjected to an etching and cleaning treatment before magnetron sputtering.

[0020] Furthermore, the etching cleaning method is as follows: adjusting the temperature of the vacuum chamber to 60-250°C, evacuating the vacuum chamber to a pressure of no more than 5×10 -3 Pa, introduce 50-100 sccm of argon, turn on the bias and arc power supply, adjust the bias to -100~-150V, the duty cycle to 40-80%, the gas pressure to 0.5-1 Pa, and the current to 70-100 A to perform etching and cleaning on the substrate.

[0021] Furthermore, the temperature of the vacuum chamber was adjusted to 150°C and the vacuum was drawn to a value not greater than 5×10 -3 Pa, introduce 100 sccm of argon, turn on the bias and arc power supply, adjust the bias to -150 V, the duty cycle to 50%, the gas pressure to 1.0 Pa, and the current to 100 A for 1 h.

[0022] Furthermore, the distance between the AlScCrTaTi alloy target and the substrate (target-substrate distance) is 40-80 mm.

[0023] Furthermore, the distance between the AlScCrTaTi alloy target and the substrate is 60 mm.

[0024] Furthermore, the sputtering temperature is 150° C., and the distance between the AlScCrTaTi alloy target and the substrate is 60 mm.

[0025] In the magnetron sputtering process described above, higher sputtering power increases the degree of ionization of the argon gas, and the sputtered particles have higher kinetic energy to migrate to the substrate surface. Prolonging the deposition time and increasing the coating thickness help increase the amplitude of the ultrasonic signal generated by the coating. Furthermore, in the magnetron sputtering method, the sputtering power is 500-900 W, and the sputtering time is 3-15 hours.

[0026] Furthermore, the sputtering power is 800-900 W and the sputtering time is 7-12 h.

[0027] Furthermore, in the magnetron sputtering method, a mixed gas of argon and nitrogen with a volume ratio of (81-1):9 is introduced until the pressure in the vacuum chamber reaches 0.6-4.0 Pa.

[0028] The second aspect of the present invention further provides a high-temperature-resistant and radiation-resistant AlN-based piezoelectric coating material prepared by any one of the above-mentioned preparation methods.

[0029] The AlN-based piezoelectric coating material provided by the present invention possesses excellent piezoelectric properties, high mechanical properties, high temperature resistance, and radiation resistance, and can generate a variety of ultrasonic waves. The AlN-based piezoelectric coating material maintains its surface morphology and ultrasonic excitation performance even when used at 700°C.

[0030] The third aspect of the present invention further provides an application of the high-temperature and radiation-resistant AlN-based piezoelectric coating material described in any one of the above items in the preparation of stress detection sensors for stress detection in nuclear facilities.

[0031] Compared with the prior art, the present invention is beneficial in that:

[0032] 1. The present invention provides a method for preparing a high-temperature-resistant AlN-based piezoelectric coating that can excite multiple ultrasonic waves. The AlN-based piezoelectric coating is prepared by radio frequency magnetron sputtering. By synergistically adjusting different deposition temperatures, sputtering power, deposition gas pressure, the flow ratio of argon and nitrogen, and the distance between the target material and the substrate, a piezoelectric coating material that simultaneously excites different waveforms such as ultrasonic shear waves, ultrasonic longitudinal waves, and ultrasonic longitudinal-shear waves can be prepared.

[0033] 2. Unlike traditional ZnO piezoelectric coatings, the AlScCrTaTiN piezoelectric coating provided by the present invention is a hard coating with high hardness, high wear resistance, high corrosion resistance, high temperature resistance and radiation resistance; it can also be used at 700°C and can be used for a long time under harsh working conditions, and it is simple to prepare and has high working efficiency.

[0034] 3. The AlN-based piezoelectric coating produced by this invention can be used to fabricate ultrasonic sensors for stress monitoring of various materials, equipment, and structures, including but not limited to steel plates, welds, and steel pipes. More importantly, it can be used to fabricate stress detection sensors specifically for nuclear equipment, nuclear facilities, and nuclear structures, ensuring the safe operation of advanced nuclear power plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1These are ultrasonic signal diagrams of the AlScN thin film prepared using the preparation method of Comparative Example 1. (a) is the ultrasonic signal diagram of the AlScN thin film without applying a bias voltage, and (b) is the ultrasonic signal diagram of the AlScN thin film with applying a -50V bias voltage.

[0036] Figure 2 Graphs showing ultrasonic signals of the AlCrN film prepared by the preparation method of Comparative Example 2 under high-temperature annealing (700°C annealing for 5 h, 10 h, and 50 h).

[0037] Figure 3 This is the ultrasonic signal diagram of Comparative Example 2 after irradiation. DETAILED DESCRIPTION

[0038] The technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0039] In some embodiments provided by the present invention, a method for preparing a high-temperature resistant and radiation-resistant AlN-based piezoelectric coating material is provided, which mainly includes the following steps: (1) using an AlScCrTaTi alloy target material to form an AlScCrTaTiN piezoelectric coating on the surface of a substrate by a magnetron sputtering method; (2) in the AlScCrTaTi alloy target material, the proportion of the number of doped atoms of Al is not less than 70%, and the proportion of the number of doped atoms of Sc, Cr, Ta and Ti is not less than 5%.

[0040] Optionally, in the AlScCrTaTi alloy target, the number of doped atoms of Sc accounts for 5-10%, the number of doped atoms of Cr accounts for 5-10%, the number of doped atoms of Ta accounts for 5-10%, and the number of doped atoms of Ti accounts for 5-10%.

[0041] Specifically, in the AlScCrTaTi alloy target, the number of doped atoms of Sc accounts for 10%, the number of doped atoms of Cr accounts for 5%, the number of doped atoms of Ta accounts for 5%, and the number of doped atoms of Ti accounts for 5%.

[0042] Optionally, the diameter of the selected AlScCrTaTi alloy target is 100-160 mm and the thickness is 4-8 mm.

[0043] Optionally, the substrate is subjected to an etching and cleaning treatment before magnetron sputtering.

[0044] Furthermore, the etching cleaning method is as follows: adjusting the temperature of the vacuum chamber to 60-250°C, evacuating the vacuum chamber to a pressure of no more than 5×10 -3 Pa, introduce 50-100 sccm of argon, turn on the bias and arc power supply, adjust the bias to -100~-150 V, the duty cycle to 40-80%, the gas pressure to 0.5-1 Pa, and the current to 70-100 A to perform etching and cleaning on the substrate.

[0045] Preferably, the etching cleaning method is as follows: adjusting the temperature of the vacuum chamber to 150°C, evacuating the vacuum chamber to a temperature not greater than 5×10 -3 Pa, 100 sccm of argon gas was introduced, the bias and arc power supplies were turned on, the bias voltage was adjusted to -150 V, the duty cycle was 50%, the gas pressure was 1.0 Pa, the current was 100 A, and the etching time was 1 h to perform etching cleaning on the substrate.

[0046] Optionally, in the magnetron sputtering method, the sputtering temperature is 60-250° C., and the distance between the AlScCrTaTi alloy target and the substrate is 40-80 mm.

[0047] Specifically, the sputtering temperature is 150° C., and the distance between the AlScCrTaTi alloy target and the substrate is 60 mm.

[0048] Optionally, in the magnetron sputtering method, the sputtering power is 500-900 W, and the sputtering time is 3-15 h.

[0049] Specifically, the sputtering power is 800-900 W, and the sputtering time is 7-12 h.

[0050] Preferably, the sputtering power is 900 W and the sputtering time is 10 h.

[0051] Optionally, in the magnetron sputtering method, a mixed gas of argon and nitrogen with a volume ratio of (81-1):9 is introduced until the pressure in the vacuum chamber reaches 0.6-4.0 Pa.

[0052] The AlN-based piezoelectric coating material provided by the present invention is prepared by a magnetron sputtering process using corresponding magnetron sputtering equipment. Generally, the structure of the magnetron sputtering equipment includes:

[0053] (1) Vacuum chamber, surrounded by the furnace wall, with a size of 400 mm × 400 mm × 400 mm.

[0054] (2) Vacuum port: located on the vacuum chamber. A vacuum pumping unit is provided to evacuate the vacuum chamber through the vacuum port.

[0055] (3) Heater, located on the vacuum chamber. The heating power can be selected as 25 kW to improve heating efficiency.

[0056] (4) Etching source, located on the vacuum chamber. It can remove impurities on the substrate surface and ensure the cleanliness of the substrate surface.

[0057] (5) Radio frequency magnetron sputtering (RF) source, located on the vacuum chamber. The AlScCrTaTi alloy target is fixed on the furnace wall of the vacuum chamber and connected to the radio frequency magnetron sputtering (RF). The power of the magnetron sputtering can be adjusted.

[0058] (6) The furnace door, sample holder, and workpiece holder are located inside the vacuum chamber. The substrate is placed on the sample holder, which is then mounted on the workpiece holder. The back of the AlScCrTaTi alloy target faces the furnace door, and the front of the AlScCrTaTi alloy target faces the sample.

[0059] This vacuum chamber layout significantly increases the plasma density within the chamber, completely immersing the workpiece in the plasma. This significantly improves the coating deposition rate, hardness, and adhesion. The technical solution of this invention also achieves a more uniform magnetic field distribution during magnetron sputtering, resulting in uniform etching of the target surface and improved coating uniformity.

[0060] In the following specific implementation cases, the properties of the prepared AlN-based piezoelectric coating material, such as high temperature resistance, radiation resistance, and mechanical strength, were tested.

[0061] The high-temperature resistance of the AlN-based piezoelectric coating was tested using an annealing test method in a muffle furnace (Model XMT-8000). The AlN-based piezoelectric coating was annealed in the muffle furnace at 700°C, a heating rate of 5°C / min, and a holding time of 50 hours. After the annealing test, the sample was cooled to room temperature and then removed from the furnace.

[0062] The test method for radiation resistance is to perform an axe damage experiment on the film surface with a neutron injection dose of 10 dPa.

[0063] The mechanical strength test method is as follows: the nanohardness and elastic modulus of the film are tested using a nanoindentation hardness tester. The test adopts the continuous stiffness method. In order to avoid the influence of the matrix effect, the depth of the film is not more than 10% of the film thickness. The hardness and elastic modulus of the film are obtained according to the Oliver-Pharr method.

[0064] Experimental Example 1: Effects of doping element type and atomic ratio on the performance of AlN-based piezoelectric coating materials

[0065] 1. Preparation of AlN-based piezoelectric coating materials

[0066] The preparation method of the AlN-based piezoelectric coating material provided in this embodiment is as follows.

[0067] (1) Select AlScCrTaTi alloy target and install it on the furnace wall in the vacuum chamber of the magnetron sputtering equipment.

[0068] The AlScCrTaTi alloy target material parameters are 150 mm in diameter and 5 mm in thickness. The atomic percentages of each element in the AlScCrTaTi alloy target material are shown in Table 1 below.

[0069] Table 1 Atomic ratio of each element in AlScCrTaTi alloy target

[0070]

[0071] Place the sample on the sample holder with the back of the AlScCrTaTi alloy target facing the furnace door and the front of the AlScCrTaTi alloy target facing the sample. Adjust the AlScCrTaTi alloy target and substrate so that the distance between them is 60 mm.

[0072] (2) Adjust the temperature in the vacuum chamber to 250℃ and evacuate the vacuum to no more than 5×10 -3 Pa. 100 sccm of argon gas (99.99% purity) was introduced, the bias and arc power were turned on, and plasma etching was performed for 1 h at -150 V, a duty cycle of 50%, and a current of 100 A to remove impurities attached to the substrate surface and improve the bonding strength between the coating material and the substrate.

[0073] (3) After etching, evacuate the vacuum chamber to a vacuum of no more than 5×10 -3 Pa, and the substrate is positioned directly over the center of the target. A mixture of argon (99.99% purity) and nitrogen (99.99% purity) is introduced with a flow ratio of 1:2 until the pressure in the vacuum chamber reaches 2.0 Pa.

[0074] (4) Turn on the RF power supply for magnetron sputtering to sputter the AlScCrTaTi alloy target onto the substrate surface to form an AlN-based piezoelectric coating material. The sputtering power is 900 W and the sputtering time is 10 h.

[0075] (5) After the AlScCrTaTiN piezoelectric coating is prepared, it is naturally cooled to room temperature to obtain an AlN-based piezoelectric coating material on the surface of the substrate.

[0076] 2. Performance test results

[0077] (1) Ultrasonic performance test

[0078] from Figure 1It can be seen that the AlScN film prepared in Comparative Example 1 under a bias of 0 V can excite ultrasonic longitudinal waves, and the AlScN film prepared under a bias of -50 V can excite ultrasonic shear waves. In the absence of a bias, the AlScCrTaTiN film prepared in Example 3 has a (002) orientation and can excite ultrasonic longitudinal waves. When a bias voltage is too high, the particles have higher energy, causing the structure of the film to be destroyed and the (002) preferred orientation to be lost, resulting in the excitation of shear waves.

[0079] (2) High temperature resistance test

[0080] from Figure 2 As can be seen, increasing the annealing time does not change the amplitude and position of the ultrasonic signal excited by the AlCrN piezoelectric material of Comparative Example 2. Heat treatment of the AlCrN piezoelectric material of Comparative Example 2 within the 700°C annealing temperature range does not change the waveform and intensity of the ultrasonic wave excited by the AlCrN piezoelectric material; ultrasonic longitudinal waves can be excited after heat treatment. The AlScCrTaTiN film prepared in Example 4 exhibits excellent high-temperature resistance due to the refinement of its grains and improved high-temperature resistance after element doping, and can be used at 700°C.

[0081] (3) Radiation resistance test results

[0082] from Figure 3 It can be seen that after neutron irradiation at 10 dpa, the film can still excite ultrasonic waves. AlN film has radiation resistance. After element doping, the radiation resistance of the film is improved. The AlScCrTaTiN film prepared in the example has good radiation resistance.

[0083] (4) Mechanical strength performance test results

[0084] The AlScN film prepared in Comparative Example 1 achieved a hardness of 20 GPa, and the AlCrN film prepared in Comparative Example 2 achieved a hardness of 25 GPa, representing a hardness increase of 25% and 67%, respectively, compared to pure AlN. The incorporation of the element distorts the film's lattice, significantly increasing its hardness. The AlScCrTaTiN prepared in Example 2 exhibited even higher hardness.

[0085] In summary, the AlScCrTaTiN piezoelectric coating material prepared by the preparation method provided by the present invention has high hardness, high wear resistance, high corrosion resistance, high temperature resistance and radiation resistance; it can be used for a long time under harsh working conditions of 700°C, and is simple to prepare and has high working efficiency.

[0086] The above specific embodiments describe the implementation of the present invention in detail, but the present invention is not limited to the specific details of the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a high-temperature and radiation-resistant AlN-based piezoelectric coating material, characterized in that: The following steps are involved: Using AlScCrTaTi alloy target material, an AlScCrTaTiN piezoelectric coating is formed on the surface of the substrate by magnetron sputtering method; In the AlScCrTaTi alloy target material, the proportion of doped Al atoms is not less than 70%, and the proportion of doped Sc, Cr, Ta and Ti atoms is not less than 5%.

2. The method for preparing the high temperature resistant and radiation resistant AlN-based piezoelectric coating material according to claim 1, characterized in that: In the AlScCrTaTi alloy target material, the number of doped atoms of Sc accounts for 5-10%, the number of doped atoms of Cr accounts for 5-10%, the number of doped atoms of Ta accounts for 5-10%, and the number of doped atoms of Ti accounts for 5-10%.

3. The method for preparing the high temperature resistant and radiation resistant AlN-based piezoelectric coating material according to claim 2, characterized in that: In the AlScCrTaTi alloy target material, the number of doped atoms of Sc accounts for 10%, the number of doped atoms of Cr accounts for 5%, the number of doped atoms of Ta accounts for 5%, and the number of doped atoms of Ti accounts for 5%.

4. The method for preparing the high temperature resistant and radiation resistant AlN-based piezoelectric coating material according to claim 1, characterized in that: The AlScCrTaTi alloy target has a diameter of 100-160 mm and a thickness of 4-8 mm.

5. The method for preparing the high temperature resistant and radiation resistant AlN-based piezoelectric coating material according to claim 1, characterized in that: performing an etching and cleaning process on the substrate before magnetron sputtering; Furthermore, the etching cleaning method is as follows: adjusting the temperature of the vacuum chamber to 60-250°C, evacuating the vacuum chamber to a pressure of no more than 5×10 -3 Pa, introduce 50-100 sccm of argon, turn on the bias and arc power supply, adjust the bias voltage to -100--150 V, the duty cycle to 40-80%, the gas pressure to 0.5-1 Pa, and the current to 70-100 A to perform etching and cleaning on the substrate; Furthermore, the temperature of the vacuum chamber was adjusted to 150°C and the vacuum was drawn to a value not greater than 5×10 -3 Pa, introduce 100 sccm of argon, turn on the bias and arc power supply, adjust the bias to -150 V, the duty cycle to 50%, the gas pressure to 1.0 Pa, and the current to 100 A for 1 h.

6. The method for preparing the high temperature resistant and radiation resistant AlN-based piezoelectric coating material according to claim 1, characterized in that: The distance between the AlScCrTaTi alloy target and the substrate is 40-80 mm; Furthermore, the distance between the AlScCrTaTi alloy target and the substrate is 60 mm.

7. The method for preparing the high temperature resistant and radiation resistant AlN-based piezoelectric coating material according to claim 1, characterized in that: In the magnetron sputtering method, the sputtering power is 500-900 W and the sputtering time is 3-15 h; Furthermore, the sputtering power is 800-900 W, and the sputtering time is 7-12 h.

8. The method for preparing a high-temperature-resistant and radiation-resistant AlN-based piezoelectric coating material according to claim 1, characterized in that: In the magnetron sputtering method, a mixed gas of argon and nitrogen with a volume ratio of (81-1):9 is introduced until the pressure in the vacuum chamber reaches 0.6-4.0 Pa.

9. A high-temperature-resistant and radiation-resistant AlN-based piezoelectric coating material prepared by the preparation method according to any one of claims 1 to 8.

10. Use of a high-temperature and radiation-resistant AlN-based piezoelectric coating material prepared by the preparation method according to any one of claims 1 to 8, or a high-temperature and radiation-resistant AlN-based piezoelectric coating material according to claim 9, in the preparation of a stress detection sensor for stress detection in nuclear facilities.

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