High-chromium-content chromium-aluminum target material and method for manufacturing the same

Abstract

This application relates to the technical field of powder metallurgy, specifically to a high-chromium-content chromium-aluminum target and its preparation method. The atomic percentage content of each element is: Cr 60-80 at%, with Al as the balance. The preparation method includes: uniformly mixing chromium powder and aluminum powder using zirconia balls to obtain a chromium-aluminum mixed powder; loading the obtained chromium-aluminum mixed powder into a rubber sleeve, sealing it after vacuuming, and performing cold isostatic pressing to obtain a chromium-aluminum billet; loading the obtained chromium-aluminum billet into a graphite mold, vacuuming, and heating for pre-sintering; continuing to heat while applying axial pressure for spark plasma sintering; cooling the sintered billet to room temperature in the furnace, demolding, and machining to obtain the high-chromium-content chromium-aluminum target. The preparation method provided by this application can effectively suppress component segregation, significantly improve the density and compositional uniformity of the target material, and has a short production cycle and low cost, making it suitable for the large-scale production of high-chromium-content chromium-aluminum targets.

Description

Technical Field

[0001] This application relates to the technical field of powder metallurgy, and in particular to a high-chromium-content chromium-aluminum target and its preparation method. Background Technology

[0002] Chromium-aluminum alloy coatings, possessing both the excellent high hardness, wear resistance, and corrosion resistance of chromium and the superior high-temperature oxidation resistance of aluminum, have become indispensable high-temperature protective and wear-resistant coating materials in the aerospace and high-end equipment manufacturing fields. They are widely used for high-temperature oxidation and corrosion protection of aero-engine turbine blades and hot-end components of gas turbines, as well as for the preparation of wear-resistant and strengthening coatings for precision cutting tools and high-end molds. Magnetron sputtering is the mainstream industrial process for preparing chromium-aluminum alloy coatings. The chromium-aluminum target, as the core sputtering source in the magnetron sputtering process, directly determines the deposition rate, compositional stability, mechanical properties, and service life of the sputtered coating due to its chemical composition uniformity, volumetric density, grain size, and microstructure. Studies have shown that when the chromium atom content in the chromium-aluminum target is ≥60%, the prepared chromium-aluminum-based coating can achieve higher microhardness, superior high-temperature oxidation resistance, and better hot corrosion resistance, meeting the long-term service requirements of aero-engine hot-end components under extreme conditions of temperatures above 1000℃, high-speed airflow erosion, and the coexistence of corrosive media.

[0003] Chromium-aluminum sputtering targets are typically prepared using powder metallurgy. However, due to the significant density difference between chromium and aluminum (chromium has a density of approximately 7.19 g / cm³, while aluminum has a density of approximately 2.70 g / cm³), component segregation is highly likely to occur during powder mixing, cold pressing, and sintering. This is especially true when preparing high-chromium-content chromium-aluminum sputtering targets, as chromium powder has significantly better flowability than aluminum powder, making it easier for powder particles to slide and separate, further exacerbating component segregation. Component segregation not only leads to uneven chemical composition in the billet but also severely affects densification during sintering, resulting in low density and numerous internal pores in the sintered billet. Therefore, component segregation and insufficient billet density have become two core technical challenges restricting the large-scale preparation and high-end applications of high-chromium-content chromium-aluminum sputtering targets.

[0004] Currently, the mainstream industrial process for preparing high-performance chromium-aluminum sputtering targets is hot isostatic pressing (HIP). This process involves isotropically pressing powder blanks under high temperature and high pressure simultaneously, resulting in sputtering targets with high density. However, HIP has inherent drawbacks such as long production cycles (typically more than 24 hours per batch), huge equipment investment, and high production costs. Furthermore, when preparing high-chromium-content chromium-aluminum sputtering targets, it still cannot fundamentally solve the problem of component segregation during powder pretreatment and loading, making it difficult to obtain high-chromium-content chromium-aluminum sputtering targets with highly uniform composition.

[0005] Spark plasma sintering (SPS) is a rapidly developing new powder metallurgy rapid sintering technology in recent years. This process applies axial pressure to the powder using upper and lower die punches, while simultaneously utilizing pulsed current to directly generate Joule heating and discharge plasma through the powder particles, rapidly melting the powder particle surface and achieving sintering densification. Compared to hot isostatic pressing (HIP), SPS offers significant advantages such as rapid heating (100-500℃ / min), short sintering time (typically only a few minutes to tens of minutes), high production efficiency, and ease of operation, showing broad application prospects in target material preparation. However, existing SPS processes typically employ unidirectional pressure, resulting in uneven stress distribution on the powder blank during sintering. Powder particles are prone to relative sliding and migration along the pressure direction, leading to increased component segregation. Ultimately, this results in poor component uniformity, large performance fluctuations, and low yield rates in target materials, failing to meet the stringent quality requirements of high-chromium-content chromium-aluminum targets in high-end applications such as aerospace.

[0006] In summary, existing technologies for preparing high-chromium-content chromium-aluminum targets generally suffer from severe component segregation, low density, long production cycles, high costs, or low product yields, making it difficult to simultaneously achieve both product quality and production efficiency. Therefore, developing a method for preparing high-chromium-content chromium-aluminum targets that can effectively suppress component segregation, significantly improve target density and component uniformity, while also having a short production cycle, low cost, and suitability for large-scale production is a pressing issue that needs to be addressed in this field. Summary of the Invention

[0007] To address the common problems in the preparation of high-chromium-content chromium-aluminum targets in existing technologies, such as severe component segregation, low density, long production cycle, high cost, or low product qualification rate, this application provides a high-chromium-content chromium-aluminum target and its preparation method. This preparation method can effectively suppress component segregation, significantly improve the density and component uniformity of the target material, and has a short production cycle and low cost, making it suitable for large-scale production of high-chromium-content chromium-aluminum targets.

[0008] In a first aspect, this application provides a method for preparing a high-chromium-content chromium-aluminum target material, employing the following technical solution:

[0009] A method for preparing a high-chromium-content chromium-aluminum target, wherein the atomic percentage content of each element in the chromium-aluminum target is: Cr 60~80 at%, Al as the balance;

[0010] The preparation method specifically includes the following steps:

[0011] (1) Powder mixing: Chromium powder and aluminum powder are mixed evenly using zirconia balls to obtain chromium-aluminum mixed powder; the purity of the chromium powder is ≥99.8wt% and the particle size is -500 mesh; the purity of the aluminum powder is ≥99.8wt% and the particle size is -500 mesh;

[0012] (2) Cold isostatic pressing: The chromium-aluminum mixed powder obtained in step (1) is loaded into a rubber sleeve, vacuumed to a vacuum degree ≤1Pa and then sealed. Cold isostatic pressing is performed under a pressure of 250-350MPa for a holding time of 20-30min to obtain chromium-aluminum billet.

[0013] (3) Two-step discharge plasma sintering: The chromium-aluminum billet obtained in step (2) is loaded into a graphite mold, vacuumed to a vacuum degree ≤5Pa, heated to 400-450℃ for pre-sintering, and held for 20-30min; then the temperature is further increased to 900-1100℃, and an axial pressure of 20-30MPa is applied at the same time for discharge plasma sintering, and the holding time is 15-25min.

[0014] (4) Post-processing: The sintered billet is cooled to room temperature in the furnace, demolded and then machined to obtain the high chromium content chromium-aluminum target material.

[0015] This application limits the chromium atomic percentage content of the chromium-aluminum sputtering target to 60-80 at%. When the chromium content is below 60 at%, the high-temperature oxidation resistance and microhardness of the coating cannot meet the requirements of extreme operating conditions such as hot-end components of aero-engines; when the chromium content is above 80 at%, the brittleness of the sputtering target increases significantly, making it prone to cracking during sintering and machining, resulting in a significant decrease in product yield. Therefore, 60-80 at% is the optimal composition range that balances coating performance and sputtering target manufacturability.

[0016] This application successfully solves the two core technical problems of component segregation and insufficient density that have long existed in the preparation of high-chromium-content chromium-aluminum targets by organically combining "ultrafine powder raw materials + cold isostatic pressing + two-step discharge plasma sintering". At the same time, it overcomes the inherent defects of traditional hot isostatic pressing process, such as long production cycle and high cost, and achieves a perfect balance between product quality and production efficiency. It provides a practical and feasible technical solution for the large-scale preparation of high-chromium-content chromium-aluminum targets.

[0017] Optionally, the atomic percentage content of each element in the chromium-aluminum target is: Cr 65~75 at%, with Al as the balance.

[0018] Optionally, in step (2), the pressure of the cold isostatic pressing is 280-320 MPa.

[0019] Optionally, in step (2), the holding time for cold isostatic pressing is 22-28 min.

[0020] By limiting the pressure and holding time of cold isostatic pressing within the aforementioned range, chromium-aluminum green blanks with uniform density and moderate strength can be obtained, while effectively reducing the risk of cladding breakage and balancing production stability and efficiency. Too low a pressure will result in insufficient green blank density, leading to large deformation during subsequent sintering and increased segregation due to relative sliding between powder particles; too high a pressure will increase the risk of cladding breakage and its effect on increasing green blank density will be less pronounced. Too short a holding time will result in uneven stress distribution within the green blank and poor density consistency; too long a holding time will prolong the production cycle and reduce production efficiency.

[0021] Optionally, in step (3), the pre-sintering temperature is 410-440℃.

[0022] Optionally, in step (3), the pre-sintering holding time is 22-28 min.

[0023] By limiting the pre-sintering temperature and holding time within the above range, it is possible to effectively remove water vapor, gaseous impurities and trace oxide films adsorbed on the surface of powder particles, while avoiding compositional segregation caused by local melting of aluminum powder, thus laying a good foundation for densification in the spark plasma sintering stage.

[0024] Too low a pre-sintering temperature will result in incomplete removal of gaseous impurities, and closed pores will easily form during spark plasma sintering; too high a pre-sintering temperature will cause powder caking, reducing the density of the sintered target material. Too short a holding time will result in insufficient impurity removal; too long a holding time will prolong the production cycle and reduce production efficiency.

[0025] Optionally, in step (3), the discharge plasma sintering temperature is 950-1050℃.

[0026] Optionally, in step (3), the pressure of the discharge plasma sintering is 22-28 MPa.

[0027] Optionally, in step (3), the holding and pressure holding time for discharge plasma sintering is 18-22 min.

[0028] By limiting the temperature, pressure, and holding time of discharge plasma sintering within the aforementioned range, full diffusion bonding and densification between chromium-aluminum particles can be achieved, while effectively suppressing abnormal grain growth, resulting in target material products with fine grains, uniform structure, and high density.

[0029] Too low a sintering temperature leads to insufficient interparticle bonding and inadequate density; too high a sintering temperature causes abnormal grain growth, reducing the mechanical properties and sputtering stability of the target material. Too low a sintering pressure hinders the densification process; too high a sintering pressure increases graphite mold wear and shortens mold life. Too short a holding time leads to incomplete densification; too long a holding time leads to coarse grains and prolongs the production cycle.

[0030] Optionally, in step (3), the heating rate of the pre-sintering temperature is 5-15℃ / min.

[0031] Optionally, the heating rate of the spark plasma sintering temperature is 10-20℃ / min.

[0032] Limiting the heating rate within the aforementioned range ensures a uniform temperature distribution within the billet, preventing cracks caused by excessive thermal stress, while also maintaining production efficiency. A heating rate that is too slow will prolong the production cycle and reduce efficiency; a heating rate that is too fast will lead to excessive temperature differences between the inside and outside of the billet, causing thermal stress cracks.

[0033] Optionally, in step (1), the mass ratio of the balls is 1:(3~8).

[0034] Optionally, the mass ratio of the balls is 1:(4~6).

[0035] Optionally, in step (1), the mixing time is 2-8 hours.

[0036] Optionally, the mixing time is 4-6 hours.

[0037] By limiting the ball-to-powder ratio and mixing time within the aforementioned ranges, the degree of powder oxidation can be effectively controlled while ensuring thorough and uniform mixing of chromium and aluminum powders, balancing mixing efficiency and product quality. A ball-to-powder ratio that is too low leads to low mixing efficiency and poor powder uniformity; a ball-to-powder ratio that is too high increases the risk of powder oxidation and production costs. A mixing time that is too short cannot guarantee thorough mixing of two powders with significantly different densities, easily causing localized component segregation; a mixing time that is too long results in low production efficiency, a significantly increased degree of powder oxidation, and a substantial increase in specific surface area.

[0038] Secondly, this application provides a high-chromium-content chromium-aluminum target material prepared using the above-described method. This chromium-aluminum target material has a relative density ≥98%, uniform elemental distribution, and no component segregation.

[0039] In summary, this application includes at least one of the following beneficial technical effects:

[0040] (1) Targeted solution to the segregation problem unique to high chromium systems: This application addresses the unique technical contradiction in chromium-aluminum systems with a high chromium content of 60~80 at% where "chromium powder has significantly better flowability than aluminum powder, leading to severe segregation". It uses -500 mesh ultrafine chromium powder and aluminum powder as raw materials, and significantly reduces the relative sliding and stratification between particles by reducing the flowability of the powder. At the same time, it adopts a cold isostatic pressing isotropic molding process, which makes the powder particles uniformly stressed during the molding process, and completely avoids particle migration and segregation caused by unidirectional molding. The final target material has a uniform element distribution and no obvious component segregation phenomenon.

[0041] (2) Synergistic improvement of high chromium target density: The ultrafine powder used in this application has a large specific surface area and many particle contact points, which makes the current and heat transfer more uniform during the discharge plasma sintering process, significantly improving the sintering activity of the high chromium powder; at the same time, the innovative introduction of a low temperature pre-sintering step of 400-450℃ can effectively remove gas impurities and trace oxide films adsorbed on the surface of powder particles, and avoid the formation of pores due to gas escape during the main sintering process. The final target material has a relative density of over 98%.

[0042] (3) High production efficiency and low cost: This application adopts a combination process of cold isostatic pressing + spark plasma sintering. Compared with the traditional hot isostatic pressing process, the production cycle is shortened from more than 24 hours to less than 8 hours, and the equipment investment and production cost are reduced by more than 50%. At the same time, the process has good stability and high product qualification rate, which is suitable for large-scale industrial production.

[0043] (4) Excellent and stable product performance: The high chromium content chromium-aluminum target material prepared in this application has uniform composition and high density. When used for magnetron sputtering, it can obtain a chromium-aluminum alloy coating with stable deposition rate, consistent composition, excellent mechanical properties and high temperature oxidation resistance. It can meet the long-term service requirements of hot-end components of aero-engines under extreme conditions of high temperature above 1000℃, high-speed airflow scouring and coexistence of corrosive media. Attached Figure Description

[0044] Figure 1 A process flow diagram of the preparation method of the high chromium content chromium-aluminum target provided in this application. Detailed Implementation

[0045] Before describing the embodiments of this application in detail, it should be understood that the terminology used herein is for the purpose of describing a particular embodiment only. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the term pertains.

[0046] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more.

[0047] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values, and such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0048] In this application, the terms "comprising" or "including" are open-ended expressions, meaning they include the content specified in this application but do not exclude other aspects.

[0049] This application discloses a method for preparing a high-chromium-content chromium-aluminum target.

[0050] The atomic percentage content of each element is as follows: Cr 60~80 at%, Al is the balance;

[0051] Combination Figure 1 The preparation method specifically includes the following steps:

[0052] (1) Powder mixing: Chromium powder and aluminum powder are mixed evenly using zirconia balls to obtain chromium-aluminum mixed powder; the purity of the chromium powder is ≥99.8wt% and the particle size is -500 mesh; the purity of the aluminum powder is ≥99.8wt% and the particle size is -500 mesh;

[0053] (2) Cold isostatic pressing: The chromium-aluminum mixed powder obtained in step (1) is loaded into a rubber sleeve, vacuumed to a vacuum degree ≤1Pa and then sealed. Cold isostatic pressing is performed under a pressure of 250-350MPa for a holding time of 20-30min to obtain chromium-aluminum billet.

[0054] (3) Two-step discharge plasma sintering: The chromium-aluminum billet obtained in step (2) is placed into a graphite mold, vacuumed to a vacuum degree ≤5Pa, heated to 400-450℃ for pre-sintering, and held for 20-30min; then the temperature is further increased to 900-1100℃, and an axial pressure of 20-30MPa is applied at the same time for discharge plasma sintering, and the holding time is 15-25min.

[0055] (4) Post-processing: The sintered billet is cooled to room temperature in the furnace, demolded and then machined to obtain the high chromium content chromium-aluminum target material.

[0056] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0057] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0058] The present application will be further described in detail below with reference to the embodiments and test results.

[0059] Example 1

[0060] This embodiment provides a high-chromium-content chromium-aluminum sputtering target. The atomic percentage content of each element is: Cr 70 at%, Al 30 at%.

[0061] The preparation method of the above-mentioned high-chromium-content chromium-aluminum target material specifically includes the following steps:

[0062] (1) Powder mixing: Weigh chromium powder and aluminum powder with a purity ≥ 99.8 wt% and a particle size of -500 mesh according to the above atomic percentage. Add the chromium powder, aluminum powder and zirconia balls together into a three-dimensional mixer and mix for 5 hours to ensure uniform mixing and obtain chromium-aluminum mixed powder; wherein, the mass ratio of ball to material is 1:5.

[0063] (2) Cold isostatic pressing: The chromium-aluminum mixed powder obtained in step (1) is loaded into a rubber sleeve, vacuumed to a vacuum degree ≤1Pa and then sealed. It is placed in a cold isostatic press and subjected to cold isostatic pressing at a pressure of 300MPa for 25 minutes to obtain chromium-aluminum billet.

[0064] (3) Two-step discharge plasma sintering: After trimming the chromium-aluminum billet obtained in step (2), it is placed into a graphite mold and put into a discharge plasma sintering furnace. The vacuum is evacuated to a vacuum degree ≤5Pa. First, the temperature is raised to 425℃ at a heating rate of 10℃ / min for pre-sintering and held for 25min. Then, the temperature is raised to 1000℃ at a heating rate of 15℃ / min and an axial pressure of 25MPa is applied at the same time for discharge plasma sintering. The holding time is 20min.

[0065] (4) Post-processing: After sintering, turn off the heating power supply, keep the pressure constant, and let the billet cool to room temperature with the furnace. After demolding, the high chromium content chromium-aluminum target material with the required shape and size is obtained by machining processes such as turning, milling and grinding.

[0066] Example 2-3

[0067] The above embodiment provides a high-chromium-content chromium-aluminum target material. The difference between this embodiment and Embodiment 1 is that the pressure used in step (2) for cold isostatic pressing is different, as shown in Table 1. The remaining preparation steps and process parameters are the same as in Embodiment 1.

[0068] Examples 4-5

[0069] The above embodiment provides a high-chromium-content chromium-aluminum target material. The difference between this embodiment and Embodiment 1 is that the holding time in step (2) of cold isostatic pressing is different, as shown in Table 1. The remaining preparation steps and process parameters are the same as in Embodiment 1.

[0070] Examples 6-7

[0071] The above embodiment provides a high-chromium-content chromium-aluminum target. The difference between this embodiment and Embodiment 1 is that the pre-sintering temperature in step (3) is different, as shown in Table 1. The remaining preparation steps and process parameters are the same as in Embodiment 1.

[0072] Examples 8-9

[0073] The above embodiment provides a high-chromium-content chromium-aluminum target. The difference between this embodiment and Embodiment 1 is that the temperature of the discharge plasma sintering in step (3) is different, as shown in Table 1. The remaining preparation steps and process parameters are the same as in Embodiment 1.

[0074] Examples 10-11

[0075] The above embodiment provides a high-chromium-content chromium-aluminum target. The difference between this embodiment and Embodiment 1 is that the pressure during spark plasma sintering in step (3) is different, as shown in Table 1. The remaining preparation steps and process parameters are the same as in Embodiment 1.

[0076] Examples 12-13

[0077] The above embodiment provides a high-chromium-content chromium-aluminum target. The difference between this embodiment and Embodiment 1 is that the holding time during spark plasma sintering in step (3) is different, as shown in Table 1. The remaining preparation steps and process parameters are the same as in Embodiment 1.

[0078] Examples 14-17

[0079] The above embodiment provides a high-chromium-content chromium-aluminum target. It differs from Example 1 in that the atomic percentage content of each element is different, as shown in Table 1. The remaining preparation steps and process parameters are the same as in Example 1.

[0080] Comparative Example 1

[0081] This comparative example provides a high-chromium-content chromium-aluminum target material. The difference between this example and Example 1 is that the particle size of the chromium and aluminum powders used is 325-500 mesh. All other preparation steps and process parameters are the same as in Example 1.

[0082] Comparative Example 2

[0083] This comparative example provides a high-chromium-content chromium-aluminum target. The difference between this example and Example 1 is that the cold isostatic pressing in step (2) is replaced with unidirectional molding. Specifically, the mixed chromium-aluminum powder is loaded into a steel mold and unidirectionally molded under a pressure of 300 MPa for 25 minutes to obtain the chromium-aluminum billet. The remaining preparation steps and process parameters are the same as in Example 1.

[0084] Comparative Example 3

[0085] This comparative example provides a high-chromium-content chromium-aluminum target. The difference between this example and Example 1 is that the cold isostatic pressing process in step (2) is omitted, and the chromium-aluminum mixed powder obtained in step (1) is directly loaded into a graphite mold for spark plasma sintering. All other preparation steps and process parameters are the same as in Example 1.

[0086] Comparative Example 4

[0087] This comparative example provides a high-chromium-content chromium-aluminum target. The difference between this example and Example 1 is that step (3) omits the pre-sintering process; instead, the cold isostatically pressed chromium-aluminum billet is placed into a graphite mold and directly heated to 1000°C for spark plasma sintering. The remaining preparation steps and process parameters are the same as in Example 1.

[0088] Performance testing

[0089] The relative densities of the high-chromium-content chromium-aluminum targets prepared in the above examples and comparative examples were measured, and surface scanning analysis was performed using an energy dispersive spectroscopy (EDS) instrument.

[0090] The test results are shown in Table 1.

[0091] Table 1. Some preparation parameters and test results of high-chromium-content chromium-aluminum sputtering targets prepared in the examples and comparative examples.

[0092]

[0093] As shown in Table 1, within the range of all process parameters specified in this application (including the upper and lower limits of each parameter such as cold isostatic pressing pressure 250-350MPa, pre-sintering temperature 400-450℃, and spark plasma sintering 900-1100℃), the prepared chromium-aluminum target materials have a dense structure of ≥98%. Furthermore, surface scanning analysis by energy dispersive spectroscopy (EDS) confirms that the chromium and aluminum elements in all embodiments are uniformly distributed without component segregation, fully meeting the stringent requirements for target material quality in high-end application fields such as aerospace.

[0094] Within a chromium content range of 60-80 at%, the preparation method described in this application can stably produce target materials with satisfactory performance. Specifically, when the chromium content is 65-75 at%, the relative density of the target material is ≥99%, achieving an optimal balance between high-temperature oxidation resistance, microhardness, and machinability.

[0095] Comparing Example 1 and Comparative Example 1, it is evident that using -500 mesh ultrafine powder is a key prerequisite for suppressing component segregation in high-chromium systems. With coarser powder particle size, flowability significantly increases. For a 70 at% high-chromium content system, the flowability advantage of chromium powder is even more pronounced, making relative sliding and stratification between powder particles more likely, leading to intensified segregation. Simultaneously, coarser powder has a smaller specific surface area, reducing sintering activity and significantly decreasing density under the same process conditions.

[0096] Comparing Example 1 and Comparative Examples 2-3, it is evident that cold isostatic pressing is a necessary step to avoid component segregation. Unidirectional molding, due to uneven stress on powder particles in all directions, easily leads to relative sliding and migration along the pressure direction. Omitting the cold isostatic pressing step results in significant blank shrinkage during spark plasma sintering, and the difference in shrinkage rates between high-chromium powder and aluminum powder further exacerbates the relative sliding between particles. Neither method can yield a target material with uniform composition.

[0097] Comparing Example 1 and Comparative Example 4, it is evident that low-temperature pre-sintering is a necessary step in obtaining high-density target materials. Without pre-sintering, gaseous impurities adsorbed on the surface of the high-chromium powder are not completely removed, and gas escape during the main sintering process will form a large number of closed pores, resulting in a significant decrease in the density of the target material.

[0098] In summary, this application successfully solves the two core technical challenges of component segregation and insufficient density that have long existed in the preparation of high-chromium-content chromium-aluminum targets by organically combining "ultrafine powder raw materials + cold isostatic pressing + two-step spark plasma sintering". At the same time, it overcomes the inherent defects of traditional hot isostatic pressing process, such as long production cycle and high cost, and achieves a perfect balance between product quality and production efficiency. It provides a practical and feasible technical solution for the large-scale preparation of high-chromium-content chromium-aluminum targets.

[0099] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing a high-chromium-content chromium-aluminum target, characterized in that, The atomic percentage content of each element in the chromium-aluminum target is: Cr 60~80 at%, Al is the balance; The preparation method specifically includes the following steps: (1) Powder mixing: Chromium powder and aluminum powder are mixed evenly using zirconia balls to obtain chromium-aluminum mixed powder; the purity of the chromium powder is ≥99.8wt% and the particle size is -500 mesh; the purity of the aluminum powder is ≥99.8wt% and the particle size is -500 mesh; (2) Cold isostatic pressing: The chromium-aluminum mixed powder obtained in step (1) is loaded into a rubber sleeve, vacuumed to a vacuum degree ≤1Pa and then sealed. Cold isostatic pressing is performed under a pressure of 250-350MPa for a holding time of 20-30min to obtain chromium-aluminum billet. (3) Two-step discharge plasma sintering: The chromium-aluminum billet obtained in step (2) is placed into a graphite mold, vacuumed to a vacuum degree ≤5Pa, heated to 400-450℃ for pre-sintering, and held for 20-30min; then the temperature is further increased to 900-1100℃, and an axial pressure of 20-30MPa is applied at the same time for discharge plasma sintering, and the holding time is 15-25min. (4) Post-processing: The sintered billet is cooled to room temperature in the furnace, demolded and then machined to obtain the high chromium content chromium-aluminum target material.

2. The preparation method according to claim 1, characterized in that, The atomic percentage content of each element in the chromium-aluminum target is: Cr 65~75 at%, with Al as the balance.

3. The preparation method according to claim 1, characterized in that, In step (2), the pressure of cold isostatic pressing is 280-320 MPa; Optionally, in step (2), the holding time for cold isostatic pressing is 22-28 min.

4. The preparation method according to claim 1, characterized in that, In step (3), the pre-sintering temperature is 410-440℃; Optionally, in step (3), the pre-sintering holding time is 22-28 min.

5. The preparation method according to claim 1, characterized in that, In step (3), the discharge plasma sintering temperature is 950-1050℃; Optionally, in step (3), the pressure of the discharge plasma sintering is 22-28 MPa; Optionally, in step (3), the holding and pressure holding time for discharge plasma sintering is 18-22 min.

6. The preparation method according to claim 1, characterized in that, In step (3), the heating rate of the pre-sintering temperature is 5-15℃ / min; Optionally, the heating rate of the spark plasma sintering temperature is 10-20℃ / min.

7. The preparation method according to claim 1, characterized in that, In step (1), the mass ratio of the balls to the material is 1:(3~8); Optionally, the mass ratio of the balls is 1:(4~6); Optionally, in step (1), the mixing time is 2-8 hours; Optionally, the mixing time is 4-6 hours.

8. A high-chromium-content chromium-aluminum target material prepared by the preparation method according to any one of claims 1-7.

9. The high-chromium-content chromium-aluminum sputtering target according to claim 8, characterized in that, The chromium-aluminum target material has a relative density of ≥98%, uniform element distribution, and no component segregation.

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