Laser discharge cavity inner surface coating and preparation method thereof

Abstract

The invention provides a laser discharge cavity inner surface coating and a preparation method thereof, and belongs to the technical field of plating, and the preparation method comprises the following steps: S1, carrying out high-power pulse magnetron sputtering deposition plating on a pretreated discharge cavity base material by adopting a NiCrAlHf alloy target material to obtain a discharge cavity base material with a plated bottom layer; s2, polystyrene microspheres are sprayed to the surface of the discharge cavity base material with the bottom layer plated, meanwhile, a NiCrAlHf alloy target material and an yttrium oxide target material are adopted for conducting high-power pulse magnetron sputtering gradient plating on the discharge cavity base material with the bottom layer plated, then vacuum annealing treatment is conducted, and the discharge cavity base material with the gradient plating is obtained; and S3, performing high-power pulse magnetron sputtering deposition plating on the discharge cavity base material subjected to gradient plating by adopting an yttrium oxide target material to obtain a discharge cavity base material subjected to top layer plating, and then performing vacuum annealing treatment to obtain the laser discharge cavity inner surface plating layer. The purpose that the coating on the inner surface of the discharge cavity of the laser is resistant to erosion and not prone to falling off can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of plating, and in particular to a coating on the inner surface of a laser discharge cavity and a preparation method thereof. Background Art

[0002] The laser discharge cavity experiences harsh service environments due to high-energy particle bombardment, high temperatures, and chemical reactions of the working gas. For example, when the discharge cavity of an excimer laser (such as a fluorine-based gas laser) operates at kilovolt-level high voltages and kilohertz-level pulse frequencies, the fluorine-containing working gas (such as ArF / KrF) will electrochemically react with the metal matrix (such as aluminum alloy or stainless steel) on the inner wall of the cavity, thereby generating solid fluoride or carbide impurities. These byproducts and impurities will degrade discharge stability, induce arcing, and cause arc spots on the surface of the laser discharge cavity, reducing the discharge stability and durability of the laser.

[0003] Currently, electroless nickel plating is mostly used to protect the inner wall of the discharge chamber. However, the hydrogen evolution side reaction during the electroless plating process can easily lead to pinholes in the coating, increasing the porosity of the coating. When the corrosive medium penetrates, local micro-batteries form at the pinholes in the coating, accelerating pitting corrosion and causing spalling, ultimately exposing the cavity substrate and causing failure.

[0004] Patent application publication number CN113151791A discloses a method for rapidly depositing a silver coating on the surface of an electrical contact material. The method comprises placing an electrical contact substrate in a sputtering chamber in the middle of a tubular sputtering source, the inner wall of the sputtering chamber having a silver target layer. The sputtering chamber is evacuated, and then a process gas is introduced to a preset backsplash cleaning pressure value, and backsplash cleaning is performed. The process gas pressure is adjusted to a sputtering coating pressure value, and bias sputtering coating is performed by applying a sputtering voltage between the tubular sputtering source and the electrical contact substrate, applying a bias voltage between the electrical contact substrate and the upper and lower covers of the sputtering source, and driving the electrical contact substrate to rotate. The electrical contact substrate is placed in the tubular sputtering source so that the electrical contact substrate is located in the plasma discharge region, thereby improving the deposition rate and target material utilization. During sputtering, a negative bias voltage is applied to the electrical contact substrate to effectively guide ions in the plasma discharge region to bombard the electrical contact substrate and the silver coating, thereby effectively improving the density and adhesion of the coating. Although this solution has improved the density and bonding of the coating, the coating prepared by this solution still lacks corrosion resistance during actual use.

[0005] Therefore, it is necessary to provide a coating on the inner surface of a laser discharge cavity and a preparation method thereof to solve the problems existing in the above-mentioned prior art. Summary of the Invention

[0006] In view of this, the present invention provides a laser discharge cavity inner surface coating and a preparation method thereof, which can achieve the purpose of making the laser discharge cavity inner surface coating resistant to corrosion and not easy to fall off.

[0007] To achieve the above object, the present invention provides a method for preparing a coating on the inner surface of a laser discharge cavity, comprising the following steps: Step S1, using a NiCrAlHf alloy target to perform high-power pulsed magnetron sputtering deposition coating on the pretreated discharge cavity substrate to obtain a discharge cavity substrate after bottom coating; Step S2, spraying polystyrene microspheres onto the surface of the discharge cavity substrate after the bottom layer is plated, and simultaneously performing high-power pulsed magnetron sputtering gradient plating on the discharge cavity substrate after the bottom layer is plated using a NiCrAlHf alloy target and a yttrium oxide target, and then performing vacuum annealing to obtain a discharge cavity substrate after the gradient plating; Step S3: using an yttrium oxide target to perform high-power pulsed magnetron sputtering deposition coating on the discharge cavity substrate after gradient coating to obtain a discharge cavity substrate after top coating, and then performing vacuum annealing treatment to obtain a coating on the inner surface of the laser discharge cavity.

[0008] High-power pulsed magnetron sputtering technology is used to deposit and coat the inner surface of the discharge chamber, and a high pulse peak power and a low duty cycle are used to achieve a high ionization rate. Its peak power is 100 times that of ordinary magnetron sputtering, and the plasma density is high. There will be no large particles on the surface of the sputtered deposited coating, which can achieve a high density of the coating. At the same time, it can also regulate the microstructure of the coating, reduce the stress in the coating, and improve the bonding strength between the coating and the substrate.

[0009] This solution uses a NiCrAlHf alloy as the base coating. Ni, the main component of the coating, has a high melting point and a low diffusion coefficient, which can provide the coating with high-temperature structural stability. Ni can also form a face-centered cubic structural matrix with good ductility, which can relieve thermal stress and reduce coating cracking. Al and Cr can be oxidized to form aluminum oxide and chromium oxide. Aluminum oxide has an extremely low oxygen diffusion coefficient and can effectively block the inward diffusion of oxygen. Chromium oxide can resist the erosion of corrosive gases generated by discharge during laser operation, improving the corrosion resistance of the discharge cavity. Hf is also introduced into the base coating. It has an extremely high melting point and can improve the thermal stability of the coating. Hf also has the effect of pinning grain boundaries, which can enhance the bonding strength of aluminum oxide and chromium oxide, promote the improvement of the coating adhesion strength, and avoid peeling.

[0010] During gradient plating, polystyrene microspheres are sprayed onto the discharge chamber substrate. During the subsequent vacuum annealing process, these microspheres form nanoscale pores within the gradient coating, reducing thermal conductivity and mitigating deformation caused by thermal stress, thereby enhancing the coating's resistance to thermal shock. Gradient coating creates a continuous coefficient of thermal expansion from the bottom layer to the top layer, ensuring a smooth transition in thermal expansion. This prevents thermal stress-induced cracking, which in turn allows corrosive elements to penetrate the top layer, eroding the bottom layer and causing coating spalling.

[0011] Yttrium oxide is used as the top coating. During the laser discharge process, under high-energy particle bombardment, the probability of yttrium oxide atoms being sputtered off the surface is far lower than that of conventional metals, making it highly resistant to plasma erosion. Yttrium oxide also absorbs less gas on its surface and has a low outgassing rate, which helps maintain a stable vacuum within the discharge chamber. Furthermore, the top coating can cover the pores formed by the polystyrene microspheres during gradient coating, preventing the porous coating from being more susceptible to corrosion. It also strengthens the bond between the top coating and the gradient coating.

[0012] Finally, the coating is vacuum annealed to release the internal stress accumulated in the multi-layer deposition, promote further interdiffusion between the interfaces of each coating layer, enhance the interlayer bonding force, and help improve the integrity of the three coating layers.

[0013] Preferably, in step S1, the preparation step of the pre-treated discharge cavity substrate includes: polishing the discharge cavity substrate to make its Ra≤0.8 μm, roughening it by sandblasting with alumina sand after cleaning, and then performing glow discharge to obtain the pre-treated discharge cavity substrate.

[0014] Preferably, the cleaning step includes: placing the polished discharge cavity substrate in acetone, ultrasonically treating it to remove oil, then immersing the discharge cavity substrate in anhydrous ethanol, ultrasonically treating it to remove organic matter, and finally rinsing it with deionized water and drying it with nitrogen.

[0015] The discharge chamber substrate is pretreated by using acetone, ethanol and deionized water to thoroughly remove grease, organic matter, oxides and tiny particle pollutants. It is then sandblasted with alumina sand to roughen the surface, forming a uniform micron-level concave-convex structure on the discharge chamber surface. This significantly increases the actual contact area between the coating and the substrate, providing a strong mechanical interlocking effect for the subsequently deposited coating, and can effectively improve the bonding strength between the coating and the discharge chamber surface.

[0016] Preferably, the mesh size of the alumina sand is 180-220 meshes.

[0017] Preferably, the preparation of the NiCrAlHf alloy target comprises the following steps: weighing high-purity Ni, Cr, Al and Ni-Hf master alloy according to the atomic ratio of Ni, Cr, Al and Hf of 60:15:23:2, melting and crushing them into powder under argon protection, then sintering and densifying by hot isostatic pressing, annealing, cutting and polishing to obtain the NiCrAlHf alloy target.

[0018] The entire preparation process of NiCrAlHf alloy target is carried out in an oxygen-free environment to avoid oxidation of Al and Hf. It is sintered and densified by hot isostatic pressing to eliminate porosity and improve the density of the target.

[0019] Preferably, the high power of the high-power magnetron sputtering is 9-10kW; in step S1, the pulse power of the magnetron sputtering deposition coating is 10kW, the pulse width is 100μs, the frequency is 500Hz, the substrate bias is -100V, the atmosphere is Ar, the gas pressure is 0.3Pa, and the time is 3-4h; in step S2, the temperature of the vacuum annealing treatment is 600-650℃, and the time is 1.5-2.5h.

[0020] Preferably, the gradient plating operation comprises the following steps: Step S21: sputtering is performed according to the metal atomic ratio of the NiCrAlHf alloy target to the yttrium oxide target of 7:3, with a pulse power of 9 kW, a pulse width of 100 μs, a frequency of 1000 Hz, a bias voltage of -120 V, a gas pressure of 0.35 Pa, an atmosphere of Ar / O2 mixed gas, and a time of 3-4 hours; Step S22: performing sputtering coating according to a dosage of the NiCrAlHf alloy target material and the yttrium oxide target material with a metal atomic ratio of 1:1, a gas pressure of 0.4 Pa, a time of 3-4 hours, and other conditions remaining unchanged; Step S23, sputtering coating is performed according to the metal atomic ratio of the NiCrAlHf alloy target and the yttrium oxide target of 3:7, the gas pressure is 0.5 Pa, the atmosphere is Ar / O2 mixed gas, the time is 4-5 hours, and other conditions remain unchanged to complete the gradient coating.

[0021] NiCrAlHf alloy and yttrium oxide are used together for gradient plating. In the first plating step, NiCrAlHf alloy is mainly used, and a small amount of yttrium oxide is introduced to form a composite structure coating with a metal matrix embedded in yttrium oxide particles, and its thermal expansion coefficient value is close to that of the bottom coating; in the second plating step, NiCrAlHf alloy and yttrium oxide are used in the same amount, which can form a continuous composite structure on the basis of the coating prepared in the first step, and the thermal expansion coefficient value is close to that of the coating formed in the first step; in the third plating step, NiCrAlHf alloy is used as a supplement and yttrium oxide is mainly used, and its thermal expansion coefficient value is close to that of the top coating.

[0022] Preferably, in step S21, the molar ratio of Ar to O2 in the Ar / O2 mixed gas is 97:3; in step S23, the molar ratio of Ar to O2 in the Ar / O2 mixed gas is 95:5.

[0023] During the gradient plating process, oxygen is introduced into the atmosphere to ensure that yttrium oxide is fully oxidized and deposited.

[0024] Preferably, in step S3, when the discharge chamber substrate is plated by high-power pulsed magnetron sputtering deposition using the yttrium oxide target, an erbium oxide target is also used.

[0025] Erbium oxide, introduced into the top coating, has a high melting point and high stability, enhancing the coating's stability. The erbium ion radius closely matches that of yttrium, forming a stable solid solution with minimal lattice distortion. This reduces sputtering weaknesses and further enhances the coating's corrosion resistance. Erbium oxide also improves the top coating's conductivity, preventing charge accumulation that can affect discharge uniformity and reducing the risk of arcing.

[0026] Preferably, the erbium oxide target material accounts for 3%-5% of the total atomic ratio.

[0027] To achieve the above object, the present invention further provides a laser discharge cavity inner surface coating prepared by the above method for preparing a laser discharge cavity inner surface coating.

[0028] The coating on the inner surface of the laser discharge cavity prepared by this scheme can achieve strong corrosion resistance and strong bonding with the substrate, and the coating is not easy to fall off.

[0029] The above technical solution of the present invention includes at least the following beneficial effects: 1. High-power pulsed magnetron sputtering technology can achieve a high ionization rate by utilizing higher pulse peak power and lower duty cycle. Its peak power is 100 times that of ordinary magnetron sputtering. The high plasma density can achieve high density of the coating and improve the bonding strength between the coating and the substrate.

[0030] 2. Using NiCrAlHf alloy as the bottom coating can provide high-temperature structural stability for the coating, relieve thermal stress, reduce coating cracking, and improve the corrosion resistance of the discharge chamber; the pinning effect of Hf on the grain boundaries promotes the improvement of the coating adhesion strength.

[0031] 3. The gradient coating forms the continuity of the thermal expansion coefficient value from the bottom coating to the top coating, which plays a role of smooth transition. It can avoid the cracking of the coating caused by thermal stress, and then the corrosion elements penetrate the top coating, erode the bottom coating, and cause the coating to peel off. DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0033] Example 1 The discharge cavity substrate was polished to Ra≤0.8μm, then immersed in acetone and ultrasonically treated for 10 minutes to clean and remove oil. The discharge cavity substrate was then placed in anhydrous ethanol and ultrasonically treated for 15 minutes to clean and remove organic matter. Finally, it was rinsed with 60℃ deionized water for 10 minutes and dried with nitrogen to complete the cleaning operation.

[0034] The discharge cavity substrate was sandblasted and roughened using 180-220 mesh alumina sand to increase the surface roughness Ra to 2-3 μm. Finally, a plasma cleaning machine was used to perform glow discharge cleaning on the sandblasted and roughened discharge cavity substrate for 30 minutes to obtain a pretreated discharge cavity substrate.

[0035] High-purity Ni, Cr, Al and Ni-Hf master alloy were weighed according to the atomic ratio of Ni, Cr, Al and Hf of 60:15:23:2. The alloy was smelted under argon protection, and then crushed into powder with a particle size of ≤75μm. The powder was sintered by hot isostatic pressing at a sintering temperature of 1200℃ and a pressure of 125MPa. Finally, the alloy was hot rolled, annealed, cut and polished to obtain NiCrAlHf alloy target.

[0036] NiCrAlHf alloy target was used to carry out high-power pulsed magnetron sputtering deposition coating on the pretreated discharge cavity substrate. The atomic ratio of Ni, Cr, Al and Hf in the NiCrAlHf alloy target was 60:15:23:2. The process parameters were pulse power of 10 kW, pulse width of 100 μs, frequency of 500 Hz, substrate bias of -100 V, atmosphere of Ar, gas pressure of 0.3 Pa, and deposition time of 3.5 h to complete the bottom layer coating.

[0037] The surface of the discharge cavity substrate after the bottom coating was completed was sprayed with polystyrene microspheres with a particle size of 90-110 nm, and the discharge cavity substrate after the bottom coating was completed was gradient coated with NiCrAlHf alloy target and yttrium oxide target. In the first stage, sputtering was performed with a metal atomic ratio of NiCrAlHf alloy target to yttrium oxide target of 7:3. The process parameters were power of 9 kW, pulse frequency of 1000 Hz, pulse width of 100 μs, bias voltage of -120 V, gas pressure of 0.35 Pa, atmosphere of Ar / O2 mixed gas, Ar to O2 ratio of 97:3, and deposition time of 3 h. In the second stage, N Sputtering coating was performed with a metal atomic ratio of iCrAlHf alloy target and yttrium oxide target of 1:1, and the power, pulse width, pulse frequency, bias voltage and atmosphere in the process parameters remained unchanged, the gas pressure was adjusted to 0.4Pa, and the deposition time was 3.5h; in the third stage, sputtering coating was performed with a metal atomic ratio of NiCrAlHf alloy target and yttrium oxide target of 3:7, and the power, pulse width, pulse frequency and bias voltage in the process parameters remained unchanged, the atmosphere was Ar / O2 mixed gas, the ratio of Ar to O2 was 95:5, the gas pressure was 0.5Pa, the deposition time was 5h, and vacuum annealing was performed at 650℃ for 2h to complete the gradient coating.

[0038] For the top layer coating, a yttrium oxide target doped with 4% erbium oxide was used for sputtering. The parameters were power of 9 kW, pulse width of 100 μs, gas pressure of 0.45 Pa, bias voltage of -100 V, atmosphere of Ar / O2 mixed gas, ratio of Ar to O2 of 95:5, deposition time of 5 h, and the top layer coating was completed.

[0039] The discharge cavity substrate after magnetron sputtering was placed in a vacuum annealing furnace for post-treatment, and the temperature was raised to 650°C at a rate of 5°C / min, kept at this temperature for 2 hours, and then slowly cooled to room temperature to obtain the inner surface coating of the laser discharge cavity.

[0040] Example 2 The discharge cavity substrate was polished to Ra≤0.8μm, then immersed in acetone and ultrasonically treated for 10 minutes to clean and remove oil. The discharge cavity substrate was then placed in anhydrous ethanol and ultrasonically treated for 15 minutes to clean and remove organic matter. Finally, it was rinsed with 60℃ deionized water for 10 minutes and dried with nitrogen to complete the cleaning operation.

[0041] The discharge cavity substrate was sandblasted and roughened using 180-220 mesh alumina sand to increase the surface roughness Ra to 2-3 μm. Finally, a plasma cleaning machine was used to perform glow discharge cleaning on the sandblasted and roughened discharge cavity substrate for 30 minutes to obtain a pretreated discharge cavity substrate.

[0042] High-purity Ni, Cr, Al and Ni-Hf master alloy were weighed according to the atomic ratio of Ni, Cr, Al and Hf of 60:15:23:2. The alloy was smelted under argon protection, and then crushed into powder with a particle size of ≤75μm. The powder was sintered by hot isostatic pressing at a sintering temperature of 1200℃ and a pressure of 125MPa. Finally, the alloy was hot rolled, annealed, cut and polished to obtain NiCrAlHf alloy target.

[0043] NiCrAlHf alloy target was used to carry out high-power pulsed magnetron sputtering deposition coating on the pretreated discharge cavity substrate. The atomic ratio of Ni, Cr, Al and Hf in the NiCrAlHf alloy target was 60:15:23:2. The process parameters were pulse power of 10 kW, pulse width of 100 μs, frequency of 500 Hz, substrate bias of -100 V, atmosphere of Ar, gas pressure of 0.3 Pa, and deposition time of 4 h to complete the bottom layer coating.

[0044] The surface of the discharge cavity substrate after the bottom coating was completed was sprayed with polystyrene microspheres with a particle size of 90-110 nm, and the discharge cavity substrate after the bottom coating was completed was gradient coated with NiCrAlHf alloy target and yttrium oxide target. In the first stage, sputtering was performed with a metal atomic ratio of NiCrAlHf alloy target to yttrium oxide target of 7:3. The process parameters were power of 9 kW, pulse frequency of 1000 Hz, pulse width of 100 μs, bias voltage of -120 V, gas pressure of 0.35 Pa, atmosphere of Ar / O2 mixed gas, Ar to O2 ratio of 97:3, and deposition time of 3 h. In the second stage, N Sputtering coating was performed with a metal atomic ratio of iCrAlHf alloy target and yttrium oxide target of 1:1, the power, pulse width, pulse frequency, bias voltage and atmosphere in the process parameters remained unchanged, the gas pressure was adjusted to 0.4Pa, and the deposition time was 4h; in the third stage, sputtering coating was performed with a metal atomic ratio of NiCrAlHf alloy target and yttrium oxide target of 3:7, the power, pulse width, pulse frequency and bias voltage in the process parameters remained unchanged, the atmosphere was Ar / O2 mixed gas, the ratio of Ar to O2 was 95:5, the gas pressure was 0.5Pa, the deposition time was 4h, and vacuum annealing was performed at 650℃ for 1.5h to complete the gradient coating.

[0045] For the top layer coating, a yttrium oxide target doped with 3% erbium oxide was used for sputtering. The parameters were power of 9 kW, pulse width of 100 μs, gas pressure of 0.45 Pa, bias voltage of -100 V, atmosphere of Ar / O2 mixed gas, ratio of Ar to O2 of 95:5, deposition time of 6 h, and the top layer coating was completed.

[0046] The discharge cavity substrate after magnetron sputtering was placed in a vacuum annealing furnace for post-treatment, and the temperature was raised to 650°C at a rate of 5°C / min, kept at this temperature for 2 hours, and then slowly cooled to room temperature to obtain the inner surface coating of the laser discharge cavity.

[0047] Example 3 The discharge cavity substrate was polished to Ra≤0.8μm, then immersed in acetone and ultrasonically treated for 10 minutes to clean and remove oil. The discharge cavity substrate was then placed in anhydrous ethanol and ultrasonically treated for 15 minutes to clean and remove organic matter. Finally, it was rinsed with 60℃ deionized water for 10 minutes and dried with nitrogen to complete the cleaning operation.

[0048] The discharge cavity substrate was sandblasted and roughened using 180-220 mesh alumina sand to increase the surface roughness Ra to 2-3 μm. Finally, a plasma cleaning machine was used to perform glow discharge cleaning on the sandblasted and roughened discharge cavity substrate for 30 minutes to obtain a pretreated discharge cavity substrate.

[0049] High-purity Ni, Cr, Al and Ni-Hf master alloy were weighed according to the atomic ratio of Ni, Cr, Al and Hf of 60:15:23:2. The alloy was smelted under argon protection, and then crushed into powder with a particle size of ≤75μm. The powder was sintered by hot isostatic pressing at a sintering temperature of 1200℃ and a pressure of 125MPa. Finally, the alloy was hot rolled, annealed, cut and polished to obtain NiCrAlHf alloy target.

[0050] NiCrAlHf alloy target was used to carry out high-power pulsed magnetron sputtering deposition coating on the pretreated discharge cavity substrate. The atomic ratio of Ni, Cr, Al and Hf in the NiCrAlHf alloy target was 60:15:23:2. The process parameters were pulse power of 10 kW, pulse width of 100 μs, frequency of 500 Hz, substrate bias of -100 V, atmosphere of Ar, gas pressure of 0.3 Pa, and deposition time of 4 h to complete the bottom layer coating.

[0051] The surface of the discharge cavity substrate after the bottom coating was completed was sprayed with polystyrene microspheres with a particle size of 90-110 nm, and the discharge cavity substrate after the bottom coating was completed was gradient coated with NiCrAlHf alloy target and yttrium oxide target. In the first stage, sputtering was performed with a metal atomic ratio of 7:3 between NiCrAlHf alloy target and yttrium oxide target. The process parameters were power 9 kW, pulse frequency 1000 Hz, pulse width 100 μs, bias voltage -120 V, gas pressure 0.35 Pa, atmosphere was Ar / O2 mixed gas, the ratio of Ar to O2 was 97:3, and deposition time was 3.5 h. In the second stage, N Sputtering coating was performed with a metal atomic ratio of iCrAlHf alloy target and yttrium oxide target of 1:1, and the power, pulse width, pulse frequency, bias voltage and atmosphere in the process parameters remained unchanged, the gas pressure was adjusted to 0.4 Pa, and the deposition time was 3.5 h; in the third stage, sputtering coating was performed with a metal atomic ratio of NiCrAlHf alloy target and yttrium oxide target of 3:7, and the power, pulse width, pulse frequency and bias voltage in the process parameters remained unchanged, the atmosphere was Ar / O2 mixed gas, the ratio of Ar to O2 was 95:5, the gas pressure was 0.5 Pa, the deposition time was 5 h, and vacuum annealing was performed at 600 ° C for 2.5 h to complete the gradient coating.

[0052] For the top layer coating, a yttrium oxide target doped with 5% erbium oxide was used for sputtering. The parameters were power of 9 kW, pulse width of 100 μs, gas pressure of 0.45 Pa, bias voltage of -100 V, atmosphere of Ar / O2 mixed gas, ratio of Ar to O2 of 95:5, deposition time of 4 h, and the top layer coating was completed.

[0053] The discharge cavity substrate after magnetron sputtering was placed in a vacuum annealing furnace for post-treatment, and the temperature was raised to 650°C at a rate of 5°C / min, kept at this temperature for 2 hours, and then slowly cooled to room temperature to obtain the inner surface coating of the laser discharge cavity.

[0054] Example 4 The discharge cavity substrate was polished to Ra≤0.8μm, then immersed in acetone and ultrasonically treated for 10 minutes to clean and remove oil. The discharge cavity substrate was then placed in anhydrous ethanol and ultrasonically treated for 15 minutes to clean and remove organic matter. Finally, it was rinsed with 60℃ deionized water for 10 minutes and dried with nitrogen to complete the cleaning operation.

[0055] The discharge cavity substrate was sandblasted and roughened using 180-220 mesh alumina sand to increase the surface roughness Ra to 2-3 μm. Finally, a plasma cleaning machine was used to perform glow discharge cleaning on the sandblasted and roughened discharge cavity substrate for 30 minutes to obtain a pretreated discharge cavity substrate.

[0056] High-purity Ni, Cr, Al and Ni-Hf master alloy were weighed according to the atomic ratio of Ni, Cr, Al and Hf of 60:15:23:2. The alloy was smelted under argon protection, and then crushed into powder with a particle size of ≤75μm. The powder was sintered by hot isostatic pressing at a sintering temperature of 1200℃ and a pressure of 125MPa. Finally, the alloy was hot rolled, annealed, cut and polished to obtain NiCrAlHf alloy target.

[0057] NiCrAlHf alloy target was used to carry out high-power pulsed magnetron sputtering deposition coating on the pretreated discharge cavity substrate. The atomic ratio of Ni, Cr, Al and Hf in the NiCrAlHf alloy target was 60:15:23:2. The process parameters were pulse power of 10 kW, pulse width of 100 μs, frequency of 500 Hz, substrate bias of -100 V, atmosphere of Ar, gas pressure of 0.3 Pa, and deposition time of 3 h to complete the bottom layer coating.

[0058] The surface of the discharge cavity substrate after the bottom coating was completed was sprayed with polystyrene microspheres with a particle size of 90-110 nm, and the discharge cavity substrate after the bottom coating was completed was gradient coated with NiCrAlHf alloy target and yttrium oxide target. In the first stage, sputtering was performed with a metal atomic ratio of NiCrAlHf alloy target to yttrium oxide target of 7:3. The process parameters were power of 9 kW, pulse frequency of 1000 Hz, pulse width of 100 μs, bias voltage of -120 V, gas pressure of 0.35 Pa, atmosphere of Ar / O2 mixed gas, Ar to O2 ratio of 97:3, and deposition time of 4 h. In the second stage, N Sputtering coating was performed with a metal atomic ratio of iCrAlHf alloy target and yttrium oxide target of 1:1, the power, pulse width, pulse frequency, bias voltage and atmosphere in the process parameters remained unchanged, the gas pressure was adjusted to 0.4 Pa, and the deposition time was 3 hours; in the third stage, sputtering coating was performed with a metal atomic ratio of NiCrAlHf alloy target and yttrium oxide target of 3:7, the power, pulse width, pulse frequency and bias voltage in the process parameters remained unchanged, the atmosphere was Ar / O2 mixed gas, the ratio of Ar to O2 was 95:5, the gas pressure was 0.5 Pa, the deposition time was 4.5 hours, and vacuum annealing was performed at 600°C for 2 hours to complete the gradient coating.

[0059] For the top layer coating, a yttrium oxide target doped with 4% erbium oxide was used for sputtering. The parameters were power of 9 kW, pulse width of 100 μs, gas pressure of 0.45 Pa, bias voltage of -100 V, atmosphere of Ar / O2 mixed gas, ratio of Ar to O2 of 95:5, deposition time of 5.5 h, and the top layer coating was completed.

[0060] The discharge cavity substrate after magnetron sputtering was placed in a vacuum annealing furnace for post-treatment, and the temperature was raised to 650°C at a rate of 5°C / min, kept at this temperature for 2 hours, and then slowly cooled to room temperature to obtain the inner surface coating of the laser discharge cavity.

[0061] Example 5 The discharge cavity substrate was polished to Ra≤0.8μm, then immersed in acetone and ultrasonically treated for 10 minutes to clean and remove oil. The discharge cavity substrate was then placed in anhydrous ethanol and ultrasonically treated for 15 minutes to clean and remove organic matter. Finally, it was rinsed with 60℃ deionized water for 10 minutes and dried with nitrogen to complete the cleaning operation.

[0062] The discharge cavity substrate was sandblasted and roughened using 180-220 mesh alumina sand to increase the surface roughness Ra to 2-3 μm. Finally, a plasma cleaning machine was used to perform glow discharge cleaning on the sandblasted and roughened discharge cavity substrate for 30 minutes to obtain a pretreated discharge cavity substrate.

[0063] High-purity Ni, Cr, Al and Ni-Hf master alloy were weighed according to the atomic ratio of Ni, Cr, Al and Hf of 60:15:23:2. The alloy was smelted under argon protection, and then crushed into powder with a particle size of ≤75μm. The powder was sintered by hot isostatic pressing at a sintering temperature of 1200℃ and a pressure of 125MPa. Finally, the alloy was hot rolled, annealed, cut and polished to obtain NiCrAlHf alloy target.

[0064] NiCrAlHf alloy target was used to carry out high-power pulsed magnetron sputtering deposition coating on the pretreated discharge cavity substrate. The atomic ratio of Ni, Cr, Al and Hf in the NiCrAlHf alloy target was 60:15:23:2. The process parameters were pulse power of 10 kW, pulse width of 100 μs, frequency of 500 Hz, substrate bias of -100 V, atmosphere of Ar, gas pressure of 0.3 Pa, and deposition time of 4 h to complete the bottom layer coating.

[0065] The surface of the discharge cavity substrate after the bottom coating was completed was sprayed with polystyrene microspheres with a particle size of 90-110 nm, and the discharge cavity substrate after the bottom coating was completed was gradient coated with NiCrAlHf alloy target and yttrium oxide target. In the first stage, sputtering was performed with a metal atomic ratio of 7:3 between NiCrAlHf alloy target and yttrium oxide target. The process parameters were power 9 kW, pulse frequency 1000 Hz, pulse width 100 μs, bias voltage -120 V, gas pressure 0.35 Pa, atmosphere was Ar / O2 mixed gas, the ratio of Ar to O2 was 97:3, and deposition time was 3.5 h. In the second stage, N Sputtering coating was performed with a metal atomic ratio of iCrAlHf alloy target and yttrium oxide target of 1:1, and the power, pulse width, pulse frequency, bias voltage and atmosphere in the process parameters remained unchanged, the gas pressure was adjusted to 0.4Pa, and the deposition time was 3.5h; in the third stage, sputtering coating was performed with a metal atomic ratio of NiCrAlHf alloy target and yttrium oxide target of 3:7, and the power, pulse width, pulse frequency and bias voltage in the process parameters remained unchanged, the atmosphere was Ar / O2 mixed gas, the ratio of Ar to O2 was 95:5, the gas pressure was 0.5Pa, the deposition time was 4.5h, and vacuum annealing was performed at 650℃ for 2h to complete the gradient coating.

[0066] For the top layer coating, a yttrium oxide target doped with 4.5% erbium oxide was used for sputtering. The parameters were power of 9 kW, pulse width of 100 μs, gas pressure of 0.45 Pa, bias voltage of -100 V, atmosphere of Ar / O2 mixed gas, ratio of Ar to O2 of 95:5, deposition time of 4.5 h, and the top layer coating was completed.

[0067] The discharge cavity substrate after magnetron sputtering was placed in a high vacuum annealing furnace for post-treatment, and the temperature was raised to 650°C at a rate of 5°C / min, kept at this temperature for 2 hours, and then slowly cooled to room temperature to obtain the inner surface coating of the laser discharge cavity.

[0068] Example 6 The discharge cavity substrate was polished to Ra≤0.8μm, then immersed in acetone and ultrasonically treated for 10 minutes to clean and remove oil. The discharge cavity substrate was then placed in anhydrous ethanol and ultrasonically treated for 15 minutes to clean and remove organic matter. Finally, it was rinsed with 60℃ deionized water for 10 minutes and dried with nitrogen to complete the cleaning operation.

[0069] The discharge cavity substrate was sandblasted and roughened using 180-220 mesh alumina sand to increase the surface roughness Ra to 2-3 μm. Finally, a plasma cleaning machine was used to perform glow discharge cleaning on the sandblasted and roughened discharge cavity substrate for 30 minutes to obtain a pretreated discharge cavity substrate.

[0070] High-purity Ni, Cr, Al and Ni-Hf master alloy were weighed according to the atomic ratio of Ni, Cr, Al and Hf of 60:15:23:2. The alloy was smelted under argon protection, and then crushed into powder with a particle size of ≤75μm. The powder was sintered by hot isostatic pressing at a sintering temperature of 1200℃ and a pressure of 125MPa. Finally, the alloy was hot rolled, annealed, cut and polished to obtain NiCrAlHf alloy target.

[0071] NiCrAlHf alloy target was used to carry out high-power pulsed magnetron sputtering deposition coating on the pretreated discharge cavity substrate. The atomic ratio of Ni, Cr, Al and Hf in the NiCrAlHf alloy target was 60:15:23:2. The process parameters were pulse power of 10 kW, pulse width of 100 μs, frequency of 500 Hz, substrate bias of -100 V, atmosphere of Ar, gas pressure of 0.3 Pa, and deposition time of 4 h to complete the bottom layer coating.

[0072] The surface of the discharge cavity substrate after the bottom coating was completed was sprayed with polystyrene microspheres with a particle size of 90-110 nm, and the discharge cavity substrate after the bottom coating was completed was gradient coated with NiCrAlHf alloy target and yttrium oxide target. In the first stage, sputtering was performed with a metal atomic ratio of 7:3 between NiCrAlHf alloy target and yttrium oxide target. The process parameters were power 9 kW, pulse frequency 1000 Hz, pulse width 100 μs, bias voltage -120 V, gas pressure 0.35 Pa, atmosphere was Ar / O2 mixed gas, the ratio of Ar to O2 was 97:3, and deposition time was 3.5 h. In the second stage, N Sputtering coating was performed with a metal atomic ratio of iCrAlHf alloy target and yttrium oxide target of 1:1, and the power, pulse width, pulse frequency, bias voltage and atmosphere in the process parameters remained unchanged, the gas pressure was adjusted to 0.4Pa, and the deposition time was 3.5h; in the third stage, sputtering coating was performed with a metal atomic ratio of NiCrAlHf alloy target and yttrium oxide target of 3:7, and the power, pulse width, pulse frequency and bias voltage in the process parameters remained unchanged, the atmosphere was Ar / O2 mixed gas, the ratio of Ar to O2 was 95:5, the gas pressure was 0.5Pa, the deposition time was 4.5h, and vacuum annealing was performed at 650℃ for 2h to complete the gradient coating.

[0073] For the top layer coating, yttrium oxide target was used for sputtering. The parameters were power of 9kW, pulse width of 100μs, gas pressure of 0.45Pa, bias voltage of -100V, atmosphere of Ar / O2 mixed gas, ratio of Ar to O2 of 95:5, deposition time of 4.5h, and the top layer coating was completed.

[0074] The discharge cavity substrate after magnetron sputtering was placed in a high vacuum annealing furnace for post-treatment, and the temperature was raised to 650°C at a rate of 5°C / min, kept at this temperature for 2 hours, and then slowly cooled to room temperature to obtain the inner surface coating of the laser discharge cavity.

[0075] The present invention also carried out comparative examples and related tests.

[0076] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that NiCrAl target material is used instead of NiCrAlHf target material in Comparative Example 1. Other compositions and preparation methods are the same as those in Example 1, and a coating on the inner surface of the laser discharge cavity is prepared.

[0077] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that in Comparative Example 2, gradient plating is not performed. Instead, NiCrAlHf target and yttrium oxide target with an atomic ratio of 1:1 are directly sputtered and plated together. The other compositions and preparation methods are the same as those in Example 1, and a coating on the inner surface of the laser discharge cavity is prepared.

[0078] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that Comparative Example 3 adopts ordinary sputtering coating, and other compositions and preparation methods are the same as those of Example 1, and a coating on the inner surface of the laser discharge cavity is prepared.

[0079] Performance testing The inner surface coating of the laser discharge cavity prepared in Examples 1-6 and Comparative Examples 1-3 was heated to 800°C, kept warm for 10 minutes, and then placed in 25°C deionized water. After cooling and drying, the samples were inspected for cracks or detachment. The above operation was repeated until obvious cracks and detachment appeared on the samples. The number of repetitions was recorded to obtain the thermal shock resistance test results, which are shown in Table 1 below.

[0080] An excimer laser was used with an Ar / F2 mixed gas (the molar ratio of Ar to F2 being 95:5) as the working gas, and 5 million pulses were performed. The coatings on the inner surface of the laser discharge cavity prepared in Examples 1-6 and Comparative Examples 1-3 were tested for their anti-electrolytic corrosion performance and anti-corrosion performance. The arc spot density and fluorine erosion thickness were used as the test results. The test results are shown in Table 1 below.

[0081] Using ASTM C1624-05 as the test standard, the adhesion strength of the coatings on the inner surface of the laser discharge cavity prepared in Examples 1-6 and Comparative Examples 1-3 was tested. The load at which the first obvious peeling occurred was used as the result. The test results are shown in Table 1 below.

[0082] Table 1

[0083] It can be seen from Table 1 above that, compared with the laser discharge cavity inner surface coating prepared in Example 5, the thermal shock resistance number of the laser discharge cavity inner surface coating prepared in Comparative Example 1 is somewhat different, and the adhesion strength difference is more obvious, indicating that the addition of Hf can improve the thermal stability of the coating and improve the adhesion strength of the coating; the thermal shock resistance of the laser discharge cavity inner surface coating prepared in Comparative Example 2 is significantly different from that of the laser discharge cavity inner surface coating prepared in Example 5, indicating that gradient plating helps to form a stable transition in the thermal expansion coefficients between the bottom coating, the gradient coating and the top coating, thereby improving the overall thermal shock resistance of the coating and avoiding cracking and peeling of the coating; the laser discharge cavity inner surface coating prepared in Comparative Example 3 is different from the laser discharge cavity inner surface coating prepared in Example 5 in all performance aspects, indicating that the use of high-power magnetron sputtering plating can make the coating performance better.

[0084] Compared with Example 5, Example 6 did not use erbium oxide during the top layer plating, and its arc spot density and fluorine corrosion depth increased significantly, indicating that erbium oxide can enhance the corrosion resistance of the coating.

[0085] The above is a preferred embodiment of the present invention. Those skilled in the art may make several improvements and modifications without departing from the principles of the present invention. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a coating on the inner surface of a laser discharge cavity, characterized in that: The following steps are involved: Step S1, using a NiCrAlHf alloy target to perform high-power pulsed magnetron sputtering deposition coating on the pretreated discharge cavity substrate to obtain a discharge cavity substrate after bottom coating; Step S2, spraying polystyrene microspheres onto the surface of the discharge cavity substrate after the bottom layer is plated, and simultaneously performing high-power pulsed magnetron sputtering gradient plating on the discharge cavity substrate after the bottom layer is plated using a NiCrAlHf alloy target and a yttrium oxide target, and then performing vacuum annealing to obtain a discharge cavity substrate after the gradient plating; Step S3: using an yttrium oxide target to perform high-power pulsed magnetron sputtering deposition coating on the discharge cavity substrate after gradient coating to obtain a discharge cavity substrate after top coating, and then performing vacuum annealing treatment to obtain a coating on the inner surface of the laser discharge cavity.

2. The method for preparing a coating on the inner surface of a laser discharge cavity according to claim 1, characterized in that: In step S1, the preparation step of the pre-treated discharge cavity substrate includes: polishing the discharge cavity substrate to make it Ra≤0.8μm, roughening it with aluminum oxide sand by sandblasting after cleaning, and then performing glow discharge to obtain the pre-treated discharge cavity substrate.

3. The method for preparing a coating on the inner surface of a laser discharge cavity according to claim 2, characterized in that: The cleaning step includes: placing the polished discharge cavity substrate into acetone, ultrasonically treating it to remove oil, then immersing the discharge cavity substrate into anhydrous ethanol, ultrasonically treating it to remove organic matter, and finally rinsing it with deionized water and drying it with nitrogen.

4. The method for preparing a coating on the inner surface of a laser discharge cavity according to claim 2, characterized in that: The mesh number of the aluminum oxide sand is 180-220 meshes.

5. The method for preparing a coating on the inner surface of a laser discharge cavity according to claim 1, characterized in that: The preparation of the NiCrAlHf alloy target comprises the following steps: weighing high-purity Ni, Cr, Al and a Ni-Hf master alloy according to the atomic ratio of Ni, Cr, Al and Hf of 60:15:23:2, melting and crushing them into powder under argon protection, sintering and densifying them by hot isostatic pressing, annealing, cutting and polishing to obtain the NiCrAlHf alloy target.

6. The method for preparing a coating on the inner surface of a laser discharge cavity according to claim 1, characterized in that: The high power of the high-power magnetron sputtering is 9-10kW; in step S1, the pulse power of the magnetron sputtering deposition coating is 10kW, the pulse width is 100μs, the frequency is 500Hz, the substrate bias is -100V, the atmosphere is Ar, the gas pressure is 0.3Pa, and the time is 3-4h; in step S2, the temperature of the vacuum annealing treatment is 600-650℃, and the time is 1.5-2.5h.

7. The method for preparing a coating on the inner surface of a laser discharge cavity according to claim 1, characterized in that: The operation of the gradient plating comprises the following steps: Step S21: sputtering is performed according to the metal atomic ratio of the NiCrAlHf alloy target to the yttrium oxide target of 7:3, with a pulse power of 9 kW, a pulse width of 100 μs, a frequency of 1000 Hz, a bias voltage of -120 V, a gas pressure of 0.35 Pa, an atmosphere of Ar / O2 mixed gas, and a time of 3-4 hours; Step S22: performing sputtering coating according to a dosage of the NiCrAlHf alloy target material and the yttrium oxide target material with a metal atomic ratio of 1:1, a gas pressure of 0.4 Pa, a time of 3-4 hours, and other conditions remaining unchanged; Step S23, sputtering coating is performed according to the metal atomic ratio of the NiCrAlHf alloy target and the yttrium oxide target of 3:7, the gas pressure is 0.5 Pa, the atmosphere is Ar / O2 mixed gas, the time is 4-5 hours, and other conditions remain unchanged to complete the gradient coating.

8. The method for preparing a coating on the inner surface of a laser discharge cavity according to claim 7, characterized in that: In the step S21, the molar ratio of Ar to O2 in the Ar / O2 mixed gas is 97:3; in the step S23, the molar ratio of Ar to O2 in the Ar / O2 mixed gas is 95:

5.

9. The method for preparing a coating on the inner surface of a laser discharge cavity according to claim 1, characterized in that: In step S3, when the discharge chamber substrate is plated with high-power pulsed magnetron sputtering deposition using the yttrium oxide target, an erbium oxide target is also used.

10. A coating on the inner surface of a laser discharge cavity, characterized in that: The laser discharge cavity inner surface coating is prepared by the method for preparing the coating according to any one of claims 1 to 9.

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