A high purity chromium target and preparation method thereof

Abstract

The invention discloses a method for preparing a high-purity chromium target material, and the preparation method comprises the following steps: step 1, cold isostatic pressing: vacuum-packaging the chromium powder and placing it in a cold isostatic press for cold pressing to obtain a chromium block; step 2, sintering: sintering the chromium block to obtain a chromium blank; step 3, hot forging; step 4, annealing; step 5, hot rolling; step 6, processing: machining, cleaning, and vacuum-packaging the chromium blank in sequence to obtain a high-purity chromium target material; the invention also discloses a high-purity chromium target material. The preparation method of the invention adopts a combination of cold isostatic pressing, sintering, hot forging, and annealing processes, and adjusts the process parameters of each stage to control the organizational structure of the chromium target material, so as to prepare chromium targets of different sizes, uniform organization, fine grains, and high quality purity, which are suitable for the field of high-performance sputtering target material processing technology.

Description

Technical Field

[0001] The invention belongs to the technical field of powder metallurgy, and in particular relates to a high-purity chromium target material and a preparation method thereof. Background Art

[0002] With the continuous development of the manufacturing industry, modern industry has higher requirements for mechanical cutting. Traditional machining tools can no longer meet the requirements of modern industry for operations in severe environments such as high temperature, high pressure, and corrosiveness. Therefore, finding tools that are more wear-resistant, corrosion-resistant, and resistant to high temperature and high pressure is an urgent need for modern machining technology. Under such severe circumstances, hard coating tools are produced. As the most widely used material for coatings, chromium can provide wear-resistant and corrosion-resistant coatings for tools, molds, parts, decorations, sanitary ware, and other fields. Hard coating chromium, chromium nitride, and diamond-like carbon coatings can provide protection for engine components such as automotive piston rings and valve tappets, extending the service life of important parts; decorative coating chromium can provide smooth and wear-resistant surfaces for sanitary ware, watches, glasses, electronic products, and many other products.

[0003] Chromium hard coating film is mainly a protective layer of 1µm~3µm deposited on workpieces such as tool molds by physical vapor deposition or chemical vapor deposition to improve its high-temperature oxidation resistance and wear resistance. Chromium targets are often used in magnetron sputtering process. How to prepare high-quality chromium targets is the key to magnetron sputtering process.

[0004] At present, the preparation technology of chromium targets mainly adopts hot isostatic pressing and hot pressing sintering. Among them, hot isostatic pressing can produce targets with high density and uniform structure, but it needs to be prepared by large hot isostatic pressing equipment, and the hot isostatic pressing process requires long-term processing, and the production cost is high; for example, the Chinese invention patent "A method for preparing chromium rotating targets" (publication number CN116213703A) performs hot isostatic pressing under low pressure environment, and adds a constant temperature platform during the hot isostatic pressing process to preform the target, effectively reducing the deformation of the target and improving the density of the target; the process of hot pressing sintering is simpler than that of hot isostatic pressing and has lower manufacturing cost, but the disadvantage of this method is that the size of the target is limited by the mold, so this method is difficult to prepare chromium targets with a size of more than 100mm.

[0005] In summary, while ensuring the quality of chromium targets, how to improve the manufacturing process of chromium targets, prepare large-sized (target size is above 100mm) chromium targets with uniform and fine structure, and reduce the dependence of the production process on large equipment such as hot isostatic pressing is an urgent problem to be solved. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies in the above-mentioned prior art and provide a method for preparing a high-purity chromium target. The preparation method combines cold isostatic pressing, sintering, hot forging and annealing to regulate the organizational structure of the chromium target, effectively improve the density of the chromium target, refine the grains and improve the uniformity of the organization, and realize the preparation of chromium targets of different sizes, thus solving the problem that the preparation of chromium targets in the prior art relies on large equipment such as hot isostatic pressing.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing a high-purity chromium target, characterized in that the preparation method comprises the following steps:

[0008] Step 1, cold isostatic pressing: vacuum-packaging the chromium powder, and then placing it in the cavity of a cold isostatic press for cold pressing to obtain a chromium block;

[0009] Step 2: Sintering: Sintering the chromium block obtained in step 1 to obtain a chromium blank;

[0010] Step 3, hot forging: hot forging the chromium blank obtained in step 2;

[0011] Step 4: Annealing: annealing the chromium blank that has been hot forged in step 3;

[0012] Step 5, hot rolling: hot rolling the chromium billet annealed in step 4;

[0013] Step 6: Processing: The chromium billet after hot rolling in step 5 is machined, cleaned and vacuum packaged in sequence to obtain a high-purity chromium target.

[0014] The above-mentioned method for preparing a high-purity chromium target is characterized in that the particle size of the chromium powder in step 1 is 50 mesh to 325 mesh, and the mass purity is not less than 99.95%.

[0015] The above-mentioned method for preparing a high-purity chromium target is characterized in that the cold pressing treatment system in step 1 is: pressure 100MPa~300MPa, and holding time 10min~120min.

[0016] The present invention can ensure the densification of the chromium block by controlling the pressure and holding time of the cold pressing treatment.

[0017] The above-mentioned method for preparing a high-purity chromium target is characterized in that the sintering treatment system in step 2 is: after multiple gas washings, a protective gas is filled in, the temperature is raised to 700°C~1600°C at a rate of 2°C / min~50°C / min, and then kept warm for 0.5h~4h, and the protective atmosphere is argon or hydrogen.

[0018] The present invention can effectively remove the gas inside the chromium block by setting the sintering heating rate to 2°C / min-50°C / min, and achieve the purpose of rapid metallurgical bonding by setting the temperature to 700°C-1600°C because the diffusion rate of chromium particles in this temperature range is relatively fast; and the chromium block is prevented from being oxidized during the sintering process by performing sintering in a protective gas environment.

[0019] The above-mentioned method for preparing a high-purity chromium target is characterized in that, in step three, the chromium blank is coated with an anti-oxidation coating before hot forging, and after air drying, a vacuum sheathing treatment is performed using a GH3170 high-temperature alloy.

[0020] The present invention coats the chromium blank with an anti-oxidation coating before hot forging, and uses GH3170 high-temperature alloy for vacuum encapsulation treatment, so as to prevent the chromium blank from being oxidized during the hot forging process, thereby effectively improving the quality purity of the chromium target material.

[0021] The above-mentioned method for preparing a high-purity chromium target is characterized in that the hot forging process in step three is: multiple stretching and upsetting treatments are performed at 800°C~1500°C, and the length after stretching is 200%~300% of the length of the chromium billet, and the length after upsetting is 40%~50% of the length of the chromium billet.

[0022] The present invention can improve the density of the chromium target material and refine the crystal grains inside the chromium target material by controlling the length of drawing and upsetting during the hot forging process.

[0023] The above-mentioned method for preparing a high-purity chromium target is characterized in that the annealing treatment system in step 4 is: after multiple gas washings, a protective gas is filled in, the temperature is raised to 700°C~1600°C at a rate of 2°C / min~50°C / min, and then kept warm for 0.5h~4h, and the protective atmosphere is argon or hydrogen.

[0024] The invention prevents the chromium blank from being oxidized during the annealing process by performing annealing in a protective gas environment.

[0025] The above-mentioned method for preparing a high-purity chromium target is characterized in that the hot rolling temperature in step five is 600°C~1400°C, the hot rolling deformation rate of each rolling pass is 5%~20%, and the total deformation rate is greater than 10%.

[0026] The present invention sets the temperature to 600°C-1400°C for hot rolling. Within this temperature range, the deformation ability of chromium is the best, and the deformation rate of a single hot rolling can be effectively improved. Compared with the cold deformation treatment, the deformation amount is larger. The hot rolling method is selected according to the shape of the high-purity chromium target to be prepared, such as unidirectional hot rolling for rectangular high-purity chromium targets, cross hot rolling for square high-purity chromium targets, and rotary hot rolling for round high-purity chromium targets.

[0027] The above-mentioned method for preparing a high-purity chromium target is characterized in that the mass purity of the high-purity chromium target in step six is ​​not less than 99.95%.

[0028] The present invention also discloses a high-purity chromium target material, characterized in that, obtained by the above-mentioned preparation method, the high-purity chromium target material has an average grain size of no more than 50µm and an oxygen content of less than 200ppm.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] 1. The present invention combines cold isostatic pressing, sintering, hot forging and annealing processes to adjust the grain size, shape, distribution and phase composition of the chromium target material to prepare the chromium target material; cold isostatic pressing is used to make the contact between chromium powder particles closer, reduce the porosity and make the chromium powder initially formed, and cold isostatic pressing helps to reduce the internal stress between the chromium powders, laying a foundation for subsequent heat treatment; sintering causes solid phase diffusion and bonding between chromium powders, further reduces the porosity, improves the density and strength of the chromium target material, and then hot forging and annealing are used to refine the grains, improve the uniformity of the structure and eliminate residual stress; cold isostatic pressing, sintering, hot forging and annealing work together to improve the performance and quality of the chromium target material, prepare a chromium target material with uniform and fine structure, avoid the use of large equipment such as a hot isostatic press, and reduce the requirements for equipment and process conditions for the preparation of the chromium target material.

[0031] 2. The present invention adopts cold isostatic pressing, a preparation process that does not limit the material size, to avoid the size of the finished chromium target being limited by the mold. The shape of the chromium target is adjusted by subsequent hot rolling and processing, so that a chromium target with a size greater than 100 mm can be prepared.

[0032] 3. The present invention can prepare a target material with a grain size smaller than the original chromium particles by regulating the process parameters at each stage, and the grain size of the chromium target material is controlled to be below 50µm. Compared with the chromium target material prepared by the prior art, the grains are finer and more conducive to sputtering; by sintering and annealing in a protective gas environment, and coating the chromium blank with an anti-oxidation coating and a vacuum jacket before hot forging, the chromium target material is prevented from being oxidized during the preparation process, and the oxygen content of the chromium target material can be effectively reduced.

[0033] 4. The present invention can improve the diffusion rate of chromium particles and the deformation rate of a single hot rolling by controlling the sintering and hot rolling temperatures, thereby shortening the duration of the sintering and hot rolling processes and effectively shortening the preparation cycle.

[0034] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1This is a flow chart for preparing the chromium target of the present invention.

[0036] Figure 2 This is the metallographic structure diagram of the chromium target prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0037] Example 1

[0038] like Figure 1 As shown, the method for preparing the chromium target in this embodiment includes the following steps:

[0039] Step 1, cold isostatic pressing: chromium powder with a particle size of 50 mesh to 325 mesh and a mass purity of not less than 99.95% is placed in a rubber sleeve for vacuum packaging, and then placed in the cavity of a cold isostatic press, and maintained at a pressure of 270 MPa for 120 minutes to obtain a chromium block;

[0040] Step 2, sintering: the chromium block obtained in step 1 is placed in a vacuum argon atmosphere heating furnace for sintering treatment to obtain a chromium blank; the sintering treatment system is: after purging 3 times, argon gas is filled in, and then the temperature is raised to 700°C at a rate of 50°C / min, and then the temperature is kept for 1.5 hours, and the furnace is cooled;

[0041] Step 3, hot forging: the chromium blank obtained in step 2 is coated with an anti-oxidation coating, air-dried, vacuum-encapsulated with GH3170 high-temperature alloy, and then stretched and upset for multiple times at 800°C; the length after stretching is 300% of the length of the chromium blank, and the length after upsetting is 50% of the length of the chromium blank;

[0042] Step 4, annealing: the chromium blank that has been hot-forged in step 3 is placed in a vacuum atmosphere furnace for annealing treatment; the annealing treatment system is: after purging 3 times, argon gas is filled in, and then the temperature is raised to 700°C at a rate of 50°C / min, and then kept at this temperature for 0.5h, and then cooled with the furnace;

[0043] Step 5, hot rolling: the chromium billet after annealing in step 4 is cross-hot rolled at 600°C; the hot rolling has a rolling deformation rate of 10% per pass and a total deformation rate of 20%;

[0044] Step 6: Processing: The chromium billet after hot rolling in step 5 is machined, cleaned and vacuum packaged in sequence to obtain a square high-purity chromium target with a side length of 203.4 mm.

[0045] In this embodiment, the cross hot rolling can be replaced by unidirectional hot rolling to prepare a rectangular high-purity chromium target.

[0046] The high purity chromium target prepared in this embodiment was taken with a microscopic metallographic photograph. Figure 2 As shown, the average grain size of the high purity chromium target is 30 μm.

[0047] Example 2

[0048] The preparation method of the chromium target material in this embodiment comprises the following steps:

[0049] Step 1, cold isostatic pressing: chromium powder with a particle size of 50 mesh to 325 mesh and a mass purity of not less than 99.95% is placed in a rubber sleeve for vacuum packaging, and then placed in the cavity of a cold isostatic press, and maintained at a pressure of 300 MPa for 60 minutes to obtain a chromium block;

[0050] Step 2, sintering: placing the chromium block obtained in step 1 into a vacuum argon atmosphere heating furnace for sintering treatment to obtain a chromium blank; the sintering treatment system is: filling with argon gas after purging 3 times, then heating to 800°C at a rate of 10°C / min, keeping the temperature for 1.5h, and cooling with the furnace;

[0051] Step 3, hot forging: the chromium blank obtained in step 2 is coated with an anti-oxidation coating, air-dried, vacuum-encapsulated with GH3170 high-temperature alloy, and then stretched and upset for multiple times at 1000° C.; the length after stretching is 200% of the length of the chromium blank, and the length after upsetting is 45% of the length of the chromium blank;

[0052] Step 4, annealing: the chromium blank that has been stretched and upset in step 3 is placed in a vacuum atmosphere furnace for annealing; the annealing process is as follows: after purging 4 times, argon is filled in, and then the temperature is raised to 900°C at a rate of 10°C / min, and then kept at this temperature for 1 hour, and then cooled with the furnace;

[0053] Step 5, hot rolling: the chromium billet after annealing in step 4 is subjected to rotary hot rolling at 900°C; the hot rolling has a rolling deformation rate of 8% per pass and a total deformation rate of 30%;

[0054] Step 6: Processing: The chromium billet after hot rolling in step 5 is machined, cleaned and vacuum packaged in sequence to obtain a high-purity chromium target with a diameter of 304.8 mm.

[0055] Example 3

[0056] The preparation method of the chromium target material in this embodiment comprises the following steps:

[0057] Step 1, cold isostatic pressing: chromium powder with a particle size of 50 mesh to 325 mesh and a mass purity of not less than 99.95% is placed in a rubber sleeve for vacuum packaging, and then placed in the cavity of a cold isostatic press, and maintained at a pressure of 200 MPa for 90 minutes to obtain a chromium block;

[0058] Step 2, sintering: placing the chromium block obtained in step 1 into a vacuum argon atmosphere heating furnace for sintering treatment to obtain a chromium blank; the sintering treatment system is: filling with argon gas after purging 4 times, then heating to 1600°C at a rate of 10°C / min, keeping the temperature for 0.5h, and cooling with the furnace;

[0059] Step 3, hot forging: the chromium blank obtained in step 2 is coated with an anti-oxidation coating, air-dried, vacuum-encapsulated with GH3170 high-temperature alloy, and then stretched and upset for multiple times at 1000°C; the length after stretching is 200% of the length of the chromium blank, and the length after upsetting is 40% of the length of the chromium blank;

[0060] Step 4, annealing: the chromium blank that has been stretched and upset in step 3 is placed in a vacuum atmosphere furnace for annealing; the annealing treatment system is: after purging 3 times, argon gas is filled in, and then the temperature is raised to 1000°C at a rate of 10°C / min, and then kept at this temperature for 1 hour, and then cooled with the furnace;

[0061] Step 5, hot rolling: the chromium billet after annealing in step 4 is subjected to rotary hot rolling at 800°C; the hot rolling has a rolling deformation rate of 12% per pass and a total deformation rate of 40%;

[0062] Step 6: Processing: The chromium billet after hot rolling in step 5 is subjected to machining, cleaning and vacuum packaging in sequence to obtain a high-purity chromium target with a diameter of 157.0 mm.

[0063] Example 4

[0064] The preparation method of the chromium target material in this embodiment comprises the following steps:

[0065] Step 1, cold isostatic pressing: chromium powder with a particle size of 50 mesh to 325 mesh and a mass purity of not less than 99.95% is placed in a rubber sleeve for vacuum packaging, and then placed in the cavity of a cold isostatic press, and maintained at a pressure of 300 MPa for 60 minutes to obtain a chromium block;

[0066] Step 2, sintering: placing the chromium block obtained in step 1 into a vacuum argon atmosphere heating furnace for sintering treatment to obtain a chromium blank; the sintering treatment system is: filling with argon gas after purging 3 times, then heating to 800°C at a rate of 10°C / min, keeping the temperature for 1h, and cooling with the furnace;

[0067] Step 3, hot forging: the chromium blank obtained in step 2 is coated with an anti-oxidation coating, air-dried, vacuum-encapsulated with GH3170 high-temperature alloy, and then stretched and upset for multiple times at 1000° C.; the length after stretching is 250% of the length of the chromium blank, and the length after upsetting is 50% of the length of the chromium blank;

[0068] Step 4, annealing: the chromium blank that has been stretched and upset in step 3 is placed in a vacuum atmosphere furnace for annealing; the annealing treatment system is: after purging 3 times, argon gas is filled in, and then the temperature is raised to 1200°C at a rate of 10°C / min, and then kept at this temperature for 1 hour, and then cooled with the furnace;

[0069] Step 5, hot rolling: the chromium billet after annealing in step 4 is cross-hot rolled at 1400°C; the hot rolling has a rolling deformation rate of 10% per pass and a total deformation rate of 60%;

[0070] Step 6: Processing: The chromium billet after hot rolling in step 5 is machined, cleaned and vacuum packaged in sequence to obtain a square high-purity chromium target with a side length of 152.4 mm.

[0071] Example 5

[0072] The preparation method of the chromium target material in this embodiment comprises the following steps:

[0073] Step 1, cold isostatic pressing: put chromium powder with a particle size of 50 mesh to 325 mesh and a mass purity of not less than 99.95% into a rubber sleeve for vacuum packaging, and then put it into the cavity of a cold isostatic press, and keep the pressure for 10 minutes under the condition of 100 MPa to obtain a chromium block;

[0074] Step 2, sintering: placing the chromium block obtained in step 1 into a vacuum argon atmosphere heating furnace for sintering treatment to obtain a chromium blank; the sintering treatment system is: filling with argon gas after purging 3 times, then heating to 700°C at a rate of 2°C / min, keeping the temperature for 4 hours, and cooling with the furnace;

[0075] Step 3, hot forging: the chromium blank obtained in step 2 is coated with an anti-oxidation coating, air-dried, vacuum-encapsulated with GH3170 high-temperature alloy, and then stretched and upset for multiple times at 1500° C.; the length after stretching is 250% of the length of the chromium blank, and the length after upsetting is 50% of the length of the chromium blank;

[0076] Step 4, annealing: the chromium blank that has been stretched and upset in step 3 is placed in a vacuum atmosphere furnace for annealing; the annealing process is as follows: after purging 3 times, argon is filled in, and then the temperature is raised to 1600°C at a rate of 2°C / min, and then kept at this temperature for 4 hours, and then cooled with the furnace;

[0077] Step 5, hot rolling: the chromium billet after annealing in step 4 is subjected to rotary hot rolling at 600°C; the hot rolling has a rolling deformation rate of 5% per pass and a total deformation rate of 20%;

[0078] Step 6: Processing: The chromium billet after hot rolling in step 5 is subjected to machining, cleaning and vacuum packaging in sequence to obtain a high-purity chromium target with a diameter of 203.2 mm.

[0079] The high purity chromium targets prepared in Examples 1 to 5 were subjected to measurement, detection and analysis of the chromium element mass percentage content, oxygen content, average grain size and density. The specific statistical results are shown in Table 1.

[0080] Table 1 Properties of high purity chromium targets prepared in Examples 1 to 5

[0081]

[0082] It can be seen from Table 1 that the mass percentage content of chromium element in the high-purity chromium targets prepared in Examples 1 to 5 is not less than 99.95%, the oxygen content is not more than 190 ppm, the average grain size is not more than 50 μm, and the density is not less than 98.05%, indicating that the high-purity chromium targets prepared in Examples 1 to 5 have the characteristics of high purity, uniform structure and high density.

[0083] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a high-purity chromium target, characterized in that: The preparation method comprises the following steps: Step 1, cold isostatic pressing: vacuum-packaging the chromium powder, and then placing it in a cavity of a cold isostatic press for cold pressing to obtain a chromium block; the particle size of the chromium powder is 50 mesh to 325 mesh; Step 2: Sintering: Sintering the chromium block obtained in step 1 in an argon or hydrogen atmosphere to obtain a chromium blank; Step 3, hot forging: hot forging the chromium blank obtained in step 2; before the hot forging, the chromium blank is coated with an anti-oxidation coating, and after air drying, it is vacuum-encapsulated with a GH3170 high-temperature alloy; the hot forging process is: drawing and upsetting are performed multiple times at 800° C. to 1500° C., and the length after drawing is 200% to 300% of the length of the chromium blank, and the length after upsetting is 40% to 50% of the length of the chromium blank; Step 4, annealing: annealing the chromium blank after hot forging in step 3; the annealing treatment system is: after multiple gas washing, fill with protective gas, heat up to 900℃~1600℃ at a rate of 2℃ / min~50℃ / min, keep warm for 0.5h~4h, and cool with the furnace, the protective gas is argon or hydrogen; Step 5, hot rolling: hot rolling the chromium billet annealed in step 4; the hot rolling temperature is 600°C to 1400°C, the hot rolling deformation rate of each rolling pass is 5% to 20%, and the total deformation rate is greater than 10%; Step 6: Processing: The chromium billet after hot rolling in step 5 is machined, cleaned, and vacuum packaged in sequence to obtain a high-purity chromium target; the average grain size of the high-purity chromium target is not greater than 50 μm.

2. The method for preparing a high-purity chromium target according to claim 1, characterized in that: The mass purity of the chromium powder in step 1 is not less than 99.95%.

3. The method for preparing a high-purity chromium target according to claim 1, characterized in that: The cold pressing treatment system in step 1 is: pressure 100MPa~300MPa, holding time 10min~120min.

4. The method for preparing a high-purity chromium target according to claim 1, characterized in that: The sintering treatment system in step 2 is: filling with argon or hydrogen after multiple gas washings, heating to 700°C~1600°C at a rate of 2°C / min~50°C / min, then keeping the temperature for 0.5h~4h, and cooling with the furnace.

5. The method for preparing a high-purity chromium target according to claim 1, characterized in that: The mass purity of the high-purity chromium target described in step six is ​​not less than 99.95%.

6. A high purity chromium target, characterized in that: Obtained by the preparation method described in any one of claims 1 to 5, the high-purity chromium target has an oxygen content of less than 200 ppm.

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