CN118668168A - High-purity chromium target and preparation method thereof - Google Patents

Abstract

The invention discloses a preparation method of a high-purity chromium target, which comprises the following steps: step one, cold isostatic pressing: placing the chromium powder subjected to vacuum encapsulation treatment into a cold isostatic press for cold pressing treatment to obtain chromium blocks; step two, sintering: sintering the chromium block to obtain a chromium blank; step three, hot forging; step four, annealing; step five, hot rolling; step six, processing: sequentially carrying out machining, cleaning treatment and vacuum packaging on the chromium blank to obtain Gao Chunge target materials; the invention also discloses a high-purity chromium target. The preparation method of the invention combines cold isostatic pressing, sintering, hot forging and annealing processes, regulates and controls the structure of the chromium target material tissue by adjusting process parameters of each stage, prepares the chromium target material with different sizes, uniform tissue, fine crystal grains and high quality purity, and is suitable for the technical field of high-performance sputtering target material processing.

Description

A high purity chromium target and preparation method thereof

Technical Field

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

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.

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.

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 material, effectively reducing the deformation of the target material and improving the density of the target material; 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.

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

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.

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:

Step 1, cold isostatic pressing: the chromium powder is vacuum packaged and then placed in the cavity of a cold isostatic press for cold pressing to obtain a chromium block;

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

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

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

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

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 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%.

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.

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

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.

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.

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.

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 to prevent the chromium blank from being oxidized during the hot forging process, thereby effectively improving the quality purity of the chromium target material.

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 blank, and the length after upsetting is 40%~50% of the length of the chromium blank.

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 the drawing and upsetting during the hot forging process.

The above-mentioned method for preparing a high-purity chromium target is characterized in that the annealing treatment system described in step 4 is: after multiple 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.

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

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%.

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.

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%.

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.

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

1. The present invention adopts a combination of 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 the 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 the chromium powders, further reduces the porosity, and improves the density and strength of the chromium target material; then hot forging and annealing are used to refine the grains, improve the uniformity of the structure and eliminate the residual stress; cold isostatic pressing, sintering, hot forging and annealing are used to synergistically 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.

2. The present invention adopts a preparation process such as cold isostatic pressing which does not limit the material size, thereby avoiding 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.

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.

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.

The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a flow chart of the preparation of the chromium target of the present invention.

FIG. 2 is a metallographic structure diagram of the chromium target prepared in Example 1 of the present invention.

DETAILED DESCRIPTION

Example 1

As shown in FIG. 1 , the method for preparing the chromium target in this embodiment includes the following steps:

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 120 minutes under a pressure of 270 MPa to obtain a chromium block;

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 50°C/min, keeping the temperature for 1.5h, and cooling with the furnace;

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;

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 the temperature is kept for 0.5h, and then cooled with the furnace;

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%;

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.

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

A microscopic metallographic photograph was taken of the high-purity chromium target prepared in this embodiment. As shown in FIG. 2 , the average grain size of the high-purity chromium target was 30 μm.

Example 2

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

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;

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;

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;

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 4 times, argon gas 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;

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%;

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.

Example 3

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

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;

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;

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;

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;

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%;

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 157.0 mm.

Example 4

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

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 60 minutes under a pressure of 300 MPa to obtain a chromium block;

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 hour, and cooling with the furnace;

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;

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;

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%;

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.

Example 5

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

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;

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 2°C/min, and then kept at this temperature for 4 hours, and then cooled with the furnace;

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;

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 1600°C at a rate of 2°C/min, and then kept at this temperature for 4 hours, and then cooled with the furnace;

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%;

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.

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.

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

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.

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 (10)

1. The preparation method of the high-purity chromium target material is characterized by comprising the following steps of:

Step one, cold isostatic pressing: vacuum packaging chromium powder, and then placing the chromium powder into a cavity of a cold isostatic press for cold pressing treatment to obtain chromium blocks;

step two, sintering: sintering the chromium block obtained in the step one to obtain a chromium blank;

Step three, hot forging: performing hot forging treatment on the chromium blank obtained in the second step;

step four, annealing: annealing the chromium blank subjected to hot forging in the third step;

Step five, hot rolling: carrying out hot rolling treatment on the annealed chromium blank in the fourth step;

step six, processing: and (3) sequentially carrying out machining, cleaning and vacuum packaging on the chromium blank subjected to hot rolling in the step five to obtain the Gao Chunge target.

2. The method for preparing a high purity chromium target according to claim 1, wherein the particle size of the chromium powder in the first step is 50-325 mesh, and the mass purity is not less than 99.95%.

3. The method for preparing a high purity chromium target according to claim 1, wherein the cold pressing treatment in the first step is performed according to the following schedule: the pressure is 100-300 MPa, and the pressure maintaining time is 10-120 min.

4. The method for preparing a high purity chromium target according to claim 1, wherein the sintering treatment system in the second step is as follows: and (3) after multiple times of gas washing, filling protective gas, heating to 700-1600 ℃ at the speed of 2-50 ℃ per minute, preserving heat for 0.5-4 hours, and cooling along with a furnace, wherein the protective gas is argon or hydrogen.

5. The method for preparing a high-purity chromium target according to claim 1, wherein the chromium blank is coated with an antioxidant coating before the hot forging treatment in the third step, and is subjected to vacuum cladding treatment by adopting GH3170 superalloy after air drying.

6. The method for preparing a high purity chromium target according to claim 1, wherein the hot forging treatment in the third step comprises the following steps: drawing and upsetting are carried out for multiple times at 800-1500 ℃, the length of the drawn and upset blank is 200-300% of the length of the chromium blank, and the length of the upset blank is 40-50% of the length of the chromium blank.

7. The method for preparing a high-purity chromium target according to claim 1, wherein the annealing treatment system in the fourth step is as follows: and (3) after multiple times of gas washing, filling protective gas, heating to 700-1600 ℃ at the speed of 2-50 ℃ per minute, preserving heat for 0.5-4 hours, and cooling along with a furnace, wherein the protective gas is argon or hydrogen.

8. The method for preparing a high-purity chromium target according to claim 1, wherein the temperature of the hot rolling treatment in the fifth step is 600 ℃ to 1400 ℃, the rolling deformation rate of each pass of hot rolling is 5% -20%, and the total deformation rate is more than 10%.

9. The method for preparing a high purity chromium target according to claim 1, wherein the mass purity of the Gao Chunge target in the sixth step is not less than 99.95%.

10. A high purity chromium target, characterized in that it is obtained by the preparation method according to any one of claims 1 to 9, said Gao Chunge target having an average grain size of not more than 50 μm and an oxygen content of less than 200ppm.