An AI computing power transformer coating high-density Ti(C, N)-HEA-ZrO2 composite sputtering target and a preparation method thereof

Abstract

This invention relates to the field of powder metallurgy and advanced physical vapor deposition (APV) target manufacturing technology, specifically to a high-density Ti(C,N)-HEA-ZrO2 composite sputtering target for AI computing power transformer coatings and its preparation method. The composite sputtering target comprises, by mass percentage, 8–12 wt.% high-entropy alloy HEA powder, 5–10 wt.% monoclinic rod-shaped ZrO2 whiskers, and the balance being Ti(C,N) powder, WC powder, and Mo2C powder. The preparation method includes multidimensional ultrasonic-airflow fluidized composite planetary mixing and spark plasma sintering. The resulting composite sputtering target has a relative density of over 99.8%, an average Ti(C,N) grain size of 0.3–0.6 μm, and high fracture toughness.

Description

Technical Field

[0001] This invention relates to the field of powder metallurgy and advanced physical vapor deposition target manufacturing technology, specifically to a high-density Ti(C,N)-HEA-ZrO2 composite sputtering target for AI computing power transformer coating and its preparation method. Background Technology

[0002] As AI computing devices evolve towards higher power density, miniaturization, and liquid cooling, AI computing transformers face higher demands for the service stability of their insulating protective coatings. Constructing inorganic protective coatings on the surface of transformer metal substrates using physical vapor deposition (PVD) technology is one of the important technical approaches to improve heat resistance, resistance to dielectric corrosion, and electrical insulation performance.

[0003] In this type of coating system, due to the significant difference in thermal expansion coefficients between the metal substrate and the outer hard ceramic layer, an intermediate buffer layer with both strength and toughness is typically required. Ti(C,N)-based cermet materials possess good matching properties of hardness, conductivity, and toughness, making them suitable as the target material base for this type of buffer layer. To further improve the crack resistance, microstructure uniformity, and sputtering stability of the target material, a high-entropy alloy binder phase and a ZrO2 whisker reinforcing phase can be introduced into the Ti(C,N)-based cermet system, thereby constructing a Ti(C,N)-HEA-ZrO2 composite system.

[0004] However, the preparation of existing Ti(C,N)-HEA-ZrO2 composite targets still has the following shortcomings.

[0005] On the one hand, during the mixing stage, due to the significant differences in density, morphology, and stress response among Ti(C,N) ceramic powder, high-entropy alloy powder, and ZrO2 whiskers, it is difficult to simultaneously ensure the uniform dispersion of multiphase powders and the integrity of whisker morphology when using traditional V-type mixing, three-dimensional mixing, or high-energy ball milling methods. When the shearing effect during the mixing process is strong, ZrO2 whiskers with a large aspect ratio are prone to breakage, weakening their reinforcing effect; when the mixing effect is weak, it is difficult to suppress the sedimentation and segregation of heavy high-entropy alloy powder, resulting in macroscopic and microscopic compositional inhomogeneity of the powder system.

[0006] On the other hand, during the sintering stage, traditional pressureless sintering or hot isostatic pressing processes typically require higher sintering temperatures and longer holding times. While these can improve density to some extent, they also easily lead to coarsening of Ti(C,N) grains and make it difficult to simultaneously eliminate porosity and maintain fine grains. For PVD sputtering targets, residual internal porosity can easily induce abnormal partial discharge on the target surface, affecting operational stability and coating quality; while grain coarsening reduces the overall mechanical properties and processing reliability of the target.

[0007] Therefore, how to achieve highly uniform mixing of multiphase powders without damaging the morphology of ZrO2 whiskers, and simultaneously achieve rapid densification and fine-grain structure control during subsequent sintering, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] The purpose of this invention is to provide a high-density Ti(C,N)-HEA-ZrO2 composite sputtering target for AI computing power transformer coating and its preparation method, so as to at least solve the following problems existing in the prior art: ZrO2 whiskers are easy to break during the mixing process, high-entropy alloy powder is easy to segregate, and the problems of pore residue and grain coarsening coexist during sintering.

[0009] To achieve the above objectives, the present invention adopts the following technical solution.

[0010] In a first aspect, the present invention provides a high-density Ti(C,N)-HEA-ZrO2 composite sputtering target for coating AI computing power transformers, comprising, by mass percentage, 8-12 wt.% high-entropy alloy HEA powder, 5-10 wt.% monoclinic rod-shaped ZrO2 whiskers, and the balance being Ti(C,N) powder, WC powder, and Mo2C powder; wherein the relative density of the composite sputtering target is 99.8% or higher, the average size of the Ti(C,N) grains in the composite sputtering target is 0.3-0.6 μm, the aspect ratio retention rate of the ZrO2 whiskers is 95% or higher, the ZrO2 whiskers are three-dimensionally randomly distributed and uniformly dispersed in the Ti(C,N) matrix, the HEA binder phase forms a core-ring structure with the Ti(C,N) matrix, and the room temperature fracture toughness of the composite sputtering target is 10.0 MPa·m^1 / 2 or higher.

[0011] Furthermore, the aspect ratio of the monoclinic rod-shaped ZrO2 whiskers is 6–10, and the diameter is 50–100 nm.

[0012] Furthermore, the surface roughness Ra of the composite sputtering target is ≤0.4 μm.

[0013] A second aspect of the present invention provides a method for preparing the above-mentioned composite sputtering target, comprising the following steps: S1. Monoclinic rod-shaped ZrO2 whiskers, high-entropy alloy HEA powder, Ti(C,N) powder, WC powder, and Mo2C powder are mixed in an ellipsoidal container of a multidimensional ultrasonic-airflow fluidized composite planetary mixing system. No mechanical stirring blades are installed inside the ellipsoidal container. During the mixing process, the ellipsoidal container simultaneously revolves and rotates in opposite directions to form a planetary mechanical centrifugal field. A variable-frequency ultrasonic transducer matrix attached to the outside of the ellipsoidal container is connected to an external ultrasonic generator via an ultrasonic generator interface, applying 20–40 kHz alternating-frequency ultrasonic waves into the ellipsoidal container to form a variable-frequency ultrasonic field. Pulsed high-purity argon gas enters through a pulsed argon gas inlet and passes through a sintered mesh plate into the ellipsoidal container to form an airflow fluidization field. Through the coupling effect of the planetary mechanical centrifugal field, the variable-frequency ultrasonic field, and the airflow fluidization field, dispersion of ZrO2 whisker morphology is maintained, and uniform mixing of multiphase powders is achieved. S2. The premixed powder is loaded into a graphite mold and subjected to spark plasma sintering under a vacuum of no more than 5.0 × 10^-3 Pa. The spark plasma sintering includes: heating to 1100℃ at a heating rate of 80–100 ℃ / min, then heating to 1250–1350℃ at a heating rate of 20–30 ℃ / min, while simultaneously applying a mechanical axial pressure of 30–50 MPa during the heating process, and holding at 1250–1350℃ for 5–15 min to obtain a sintered body. S3. The sintered body is subjected to stress-relief annealing and machining to obtain the composite sputtering target.

[0014] Furthermore, in step S1, the monoclinic rod-shaped ZrO2 whiskers are prepared using a fluxing method.

[0015] Furthermore, in step S1, the multidimensional ultrasonic-airflow fluidization composite planetary mixing system includes an ellipsoidal material tank, and the planetary mechanical centrifugal field is formed by controlling the ellipsoidal material tank to revolve at 100-300 rpm and rotate in the opposite direction.

[0016] Further, in step S1, the frequency of the variable frequency ultrasonic field is 20-40 kHz, and the pulsed gas flow fluidization field is formed by introducing pulsed high-purity argon gas with a pressure of 0.2-0.4 MPa from the bottom of the material tank.

[0017] Further, in step S1, the mixing time is 1 to 3 hours; after mixing, vacuum drying is performed to obtain premixed powder with a coefficient of variation CV ≤ 3%.

[0018] Further, in step S2, after the heat preservation and pressure holding are completed, the pulse power supply is cut off, and the mechanical axial pressure is maintained until the temperature drops below 800 ℃ and then the pressure is released. Then argon gas is introduced and the furnace is cooled to room temperature.

[0019] Furthermore, in step S3, the stress-relief annealing is performed by holding the material at 800 °C for 2 hours in a vacuum furnace.

[0020] Furthermore, in step S3, the machining includes wire cutting and precision grinding and polishing to ensure that the surface roughness Ra of the resulting composite sputtering target is ≤0.4 μm.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are: This invention employs a multidimensional ultrasonic-airflow fluidization composite planetary mixing method, which can improve the mixing uniformity of multiphase powders while reducing the risk of whisker mechanical damage and suppressing segregation between powders of different densities.

[0022] This invention employs spark plasma sintering for rapid densification, which enables high-density forming under relatively short thermal exposure conditions and helps suppress Ti(C,N) grain coarsening.

[0023] The composite sputtering target prepared by this invention has a high relative density, fine grain structure, high whisker aspect ratio retention rate and high room temperature fracture toughness, and is suitable for physical vapor deposition preparation of insulating coating buffer layer of AI computing power transformer. Attached Figure Description

[0024] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of the multidimensional ultrasonic-airflow fluidization composite planetary mixing system used in this invention.

[0025] Figure 2 This is a SEM image of the powder after coupling and mixing in Example 1.

[0026] Figure 3 This is a magnified SEM image of the powder after coupling and mixing in Example 1.

[0027] Figure 4 The image shows the SEM morphology of the fracture surface of the Ti(C,N)-based cermet after spark plasma sintering in Example 1.

[0028] Figure 5 This is a SEM image of the powder after mixing in Comparative Example 1.

[0029] Figure 6 The image shows the SEM image of the polished surface of the Ti(C,N)-based cermet after sintering in Comparative Example 2.

[0030] In the figure: 1. Ellipsoidal material container; 2. Ti(C,N) powder; 3. HEA powder; 4. ZrO2 whiskers; 5. Sintered mesh plate; 6. Pulsed argon gas inlet; 7. Ultrasonic generator interface; 8. Variable frequency ultrasonic transducer matrix; 9. Support base. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The test methods for each performance index are as follows: relative density was determined by Archimedes' displacement method; fracture toughness was calculated by Vickers indentation method based on the length of indentation crack; whisker aspect ratio retention rate was obtained by randomly sampling the mixed powder and statistically analyzing the proportion of intact rod-shaped whiskers using scanning electron microscopy; microstructure and grain size were statistically analyzed using scanning electron microscopy and backscattered electron imaging combined with ImageJ software.

[0033] like Figure 1 As shown in the figure (the "revolution" and "rotation" and their corresponding arrows indicate the movement of the ellipsoidal tank 1 during the mixing process, and the upward arrow indicates the airflow fluidization direction formed after the pulsed argon gas enters the tank through the sintered mesh plate 5), the multidimensional ultrasonic-airflow fluidization composite planetary mixing system used in this invention includes an ellipsoidal tank 1, which is mounted on a support base 9. The ellipsoidal tank 1 is used to contain Ti(C,N) powder 2, HEA powder 3, and ZrO2 whiskers 4. A sintered mesh plate 5 is set at the bottom of the ellipsoidal tank 1. Pulsed argon gas enters through the pulsed argon gas inlet 6 and passes through the sintered mesh plate 5 into the ellipsoidal tank 1, thereby forming an upward airflow fluidization effect on the powder inside the ellipsoidal tank 1. A variable frequency ultrasonic transducer matrix 8 is set on the outer periphery of the ellipsoidal tank 1. The variable frequency ultrasonic transducer matrix 8 is connected to an external ultrasonic generator through an ultrasonic generator interface 7 to apply a variable frequency ultrasonic field to the inside of the ellipsoidal tank 1. During the mixing process, the ellipsoidal material tank 1 simultaneously revolves around the sun and rotates in the opposite direction, so that the powder in the material tank can be uniformly mixed under the synergistic effect of the planetary mechanical centrifugal field, the variable frequency ultrasonic field and the pulsed airflow fluidization field. Example

[0034] Raw material ratio Weigh out 10 wt.% high-entropy alloy HEA powder, 7.5 wt.% monoclinic rod-shaped ZrO2 whiskers, 65 wt.% Ti(C,N) powder, 10 wt.% WC powder and 7.5 wt.% Mo2C powder by mass percentage.

[0035] Mixing The above raw materials were placed in the ellipsoidal container of a multidimensional ultrasonic-airflow fluidized composite planetary mixing system. The revolution speed was set to 200 rpm, and the reverse rotation speed to 100 rpm. A 30 kHz variable frequency ultrasonic field was activated, and pulsed high-purity argon gas at a pressure of 0.3 MPa was introduced from the bottom for three-field coupled mixing for 2 hours. After mixing, vacuum drying was performed. Figure 2 and Figure 3 As shown, the test results indicate that the coefficient of variation (CV) of the obtained premixed powder is 2.1%, the aspect ratio retention rate of ZrO2 whiskers is 96.5%, the whisker morphology is intact, and there is no obvious breakage.

[0036] sintering The obtained premixed powder was loaded into a graphite mold and placed in a spark plasma sintering furnace. Under vacuum conditions, the temperature was first increased to 1100 °C at a rate of 100 °C / min, and then increased to 1300 °C at a rate of 25 °C / min. During the heating process, a mechanical axial pressure of 40 MPa was applied linearly and simultaneously. The temperature and pressure were maintained at 1300 °C for 10 min. After the holding period, the pulse power supply was cut off, and the pressure was maintained until the temperature dropped below 800 °C. Then, the pressure was released, and argon gas was introduced to cool the furnace to room temperature.

[0037] Post-processing The sintered blank was stress-relief annealed in a vacuum furnace at 800 °C for 2 h, followed by wire cutting and precision grinding and polishing to obtain the composite sputtering target.

[0038] Performance Characterization like Figure 4 As shown, the obtained target material has a relative density of 99.92%, an average Ti(C,N) grain size of 0.35 μm, and a ZrO2 whisker aspect ratio retention rate of 96.5%. The ZrO2 whiskers are three-dimensionally randomly distributed and uniformly dispersed in the Ti(C,N) matrix. The HEA binder phase forms a core-ring structure with the Ti(C,N) matrix. The room temperature fracture toughness is 10.8 MPa·m^1 / 2, and the Vickers hardness is 20.8 GPa. The target material maintained intact edges during wire cutting, with no obvious chipping observed. Example

[0039] Raw material ratio Weigh out 8 wt.% high-entropy alloy HEA powder, 10 wt.% monoclinic rod-shaped ZrO2 whiskers, 70 wt.% Ti(C,N) powder, 6 wt.% WC powder and 6 wt.% Mo2C powder by mass percentage.

[0040] Mixing The mixing method was the same as in Example 1, and the mixing time was 1.5 h.

[0041] sintering The uniformly mixed powder was placed in a spark plasma sintering furnace, and the temperature was first raised to 1100 ℃ at 80 ℃ / min, and then raised to 1350 ℃ at 20 ℃ / min. Simultaneously, a mechanical axial pressure of 50 MPa was applied, and the temperature and pressure were maintained at 1350 ℃ for 5 min.

[0042] Performance Characterization The resulting target material has a relative density of 99.85%, an average Ti(C,N) grain size of 0.32 μm, a Vickers hardness of 21.5 GPa, and a room temperature fracture toughness of 10.2 MPa·m^1 / 2. Example

[0043] Raw material ratio Weigh out 12 wt.% high-entropy alloy HEA powder, 5 wt.% monoclinic rod-shaped ZrO2 whiskers, 73 wt.% Ti(C,N) powder, 5 wt.% WC powder and 5 wt.% Mo2C powder by mass percentage.

[0044] Mixing The mixing method was the same as in Example 1, and the mixing time was 3 hours.

[0045] sintering The uniformly mixed powder was placed in a spark plasma sintering furnace and sintered at 1250 °C, with a mechanical axial pressure of 30 MPa applied and held at the temperature and pressure for 15 min.

[0046] Performance Characterization The resulting target material has a relative density of 99.80%, an average Ti(C,N) grain size of 0.42 μm, a Vickers hardness of 19.5 GPa, and a room temperature fracture toughness of 10.5 MPa·m^1 / 2.

[0047] Comparative Example 1 Raw material ratio and sintering process The raw material ratio and sintering process are the same as in Example 1.

[0048] Distinguishing features The mixing step was carried out using a traditional V-type double helix mixer for 24 hours.

[0049] Performance Characterization like Figure 5As shown, after mixing, microscopic statistical analysis revealed that approximately 68% of the ZrO2 whiskers were cut and crushed by the mechanical blades, with a whisker aspect ratio retention rate of only 32%. Approximately 4.5% high-entropy alloy composition segregation was detected on the upper and lower end faces of the target. The final target material had a relative density of 99.2% and a room-temperature fracture toughness of 7.8 MPa·m^1 / 2. Edge microcracks appeared in the sample during the demolding and cooling stage.

[0050] Comparative Example 2 Raw material proportioning and mixing process The raw material ratio is the same as in Example 1, and the mixing method adopts the multidimensional ultrasonic-airflow fluidization composite planetary mixing method in Example 1.

[0051] Distinguishing features The sintering step adopts hot isostatic pressing: the temperature is increased to 1400 ℃ at 5 ℃ / min, a pressure of 100 MPa is applied, and the temperature and pressure are held for 120 min.

[0052] Performance Characterization like Figure 6 As shown, the obtained sample has a relative density of 98.5%, and numerous micron-sized closed pores can be observed in the cross-section, with a porosity of approximately 1.5%. The average size of the Ti(C,N) grains is 1.85 μm, with localized high-entropy alloy liquid phase agglomeration. The Vickers hardness is 17.5 GPa, and the room temperature fracture toughness is 8.5 MPa·m^1 / 2. When this sample is used as a PVD target, abnormal discharge is prone to occur on the target surface, which is not conducive to obtaining a high-quality coating.

[0053] in conclusion As can be seen from the above embodiments and comparative examples, the present invention, through the synergistic effect of multidimensional ultrasonic-airflow fluidized composite planetary mixing and spark plasma sintering, can effectively maintain the integrity of ZrO2 whisker morphology, suppress multiphase powder segregation, achieve high densification and fine grain size of composite target material, and thus obtain Ti(C,N)-HEA-ZrO2 composite sputtering target material with high density, fine grain structure and high room temperature fracture toughness.

[0054] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-density Ti(C,N)-HEA-ZrO2 composite sputtering target for coating AI computing power transformers, characterized in that, By mass percentage, it includes 8–12 wt.% high-entropy alloy HEA powder, 5–10 wt.% monoclinic rod-shaped ZrO2 whiskers, and the balance Ti(C,N) powder, WC powder, and Mo2C powder. The relative density of the composite sputtering target is above 99.8%; The average size of the Ti(C,N) grains in the composite sputtering target is 0.3–0.6 μm; The ZrO2 whiskers have an aspect ratio retention rate of over 95%, and the ZrO2 whiskers are three-dimensionally randomly distributed and uniformly dispersed in the Ti(C,N) matrix. The HEA binder phase forms a core-ring structure with the Ti(C,N) matrix. The composite sputtering target has a room temperature fracture toughness of 10.0 MPa·m^1 / 2 or higher.

2. The composite sputtering target according to claim 1, characterized in that, The monoclinic rod-shaped ZrO2 whiskers have an aspect ratio of 6–10 and a diameter of 50–100 nm.

3. The composite sputtering target according to claim 1 or 2, characterized in that, The surface roughness Ra of the composite sputtering target is ≤0.4 μm.

4. A method for preparing the Ti(C,N)-HEA-ZrO2 composite sputtering target according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Monoclinic rod-shaped ZrO2 whiskers, high-entropy alloy HEA powder, Ti(C,N) powder, WC powder and Mo2C powder are placed in a multidimensional ultrasonic-airflow fluidized composite planetary mixing system for mixing to obtain premixed powder. The multidimensional ultrasonic-airflow fluidized composite planetary mixing system has no mechanical stirring blades in the tank, and planetary mechanical centrifugal field, frequency conversion ultrasonic field and pulsed airflow fluidization field are applied simultaneously during the mixing process. S2. The premixed powder is loaded into a graphite mold and subjected to spark plasma sintering under a vacuum of no more than 5.0 × 10^-3 Pa. The spark plasma sintering includes: heating to 1100 ℃ at a heating rate of 80-100 ℃ / min, then heating to 1250-1350 ℃ at a heating rate of 20-30 ℃ / min, while simultaneously applying a mechanical axial pressure of 30-50 MPa during the heating process, and holding at 1250-1350 ℃ and pressure for 5-15 min to obtain a sintered body. S3. The sintered body is subjected to stress-relief annealing and machining to obtain the composite sputtering target.

5. The preparation method according to claim 4, characterized in that, In step S1, the monoclinic rod-shaped ZrO2 whiskers are prepared by a fluxing method.

6. The preparation method according to claim 4 or 5, characterized in that, In step S1, the multidimensional ultrasonic-airflow fluidization composite planetary mixing system includes an ellipsoidal material tank, and the planetary mechanical centrifugal field is formed by controlling the ellipsoidal material tank to revolve at 100-300 rpm and rotate in the opposite direction.

7. The preparation method according to any one of claims 4 to 6, characterized in that, In step S1, the frequency of the variable frequency ultrasonic field is 20 to 40 kHz, and the pulsed gas flow fluidization field is formed by introducing pulsed high-purity argon gas with a pressure of 0.2 to 0.4 MPa from the bottom of the material tank.

8. The preparation method according to any one of claims 4 to 7, characterized in that, In step S1, the mixing time is 1 to 3 hours; after mixing, vacuum drying is performed to obtain premixed powder with a coefficient of variation CV ≤ 3%.

9. The preparation method according to any one of claims 4 to 8, characterized in that, In step S2, after the heat preservation and pressure preservation are completed, the pulse power supply is cut off, and the mechanical axial pressure is maintained until the temperature drops below 800 ℃ and then the pressure is released. Argon gas is then introduced and the furnace is cooled to room temperature.

10. The preparation method according to any one of claims 4 to 9, characterized in that, In step S3, the stress-relief annealing is performed by holding the material at 800 °C for 2 hours in a vacuum furnace.

11. The preparation method according to any one of claims 4 to 10, characterized in that, In step S3, the machining includes wire cutting and precision grinding and polishing to make the surface roughness Ra of the obtained composite sputtering target ≤ 0.4 μm.

Images