Refractory metal tungsten coating with high (110) orientation and preparation method thereof

Abstract

The invention discloses a refractory metal tungsten coating with high (110) orientation and a preparation method thereof.The tungsten coating is prepared through an arc ion plating technology and presents (110) preferred orientation, and the orientation texture coefficient is not lower than 2. The preparation method comprises the steps that firstly, a base body is pretreated; 2, bombarding and cleaning the matrix by utilizing high-energy tungsten ion flow; 3, depositing a transition tungsten coating on the cleaned substrate; and 4, preparing the tungsten coating with high (110) orientation on the substrate on which the transition tungsten coating is deposited. The tungsten coating with high (110) orientation is directly prepared by adopting an arc ion plating method, subsequent processing treatment is not needed, the process is simple, the cost is low, the tungsten coating is remarkable in orientation characteristic, compact in microstructure, uniform and flat in surface and high in interface bonding, the application reliability of the tungsten coating is remarkably improved, the service life of the tungsten coating is remarkably prolonged, and the application range of the tungsten coating is widened. The method is suitable for the fields of nuclear industry, electronic industry, aerospace and the like.

Description

Technical Field

[0001] This invention belongs to the field of surface protective coating technology, specifically relating to a refractory tungsten metal coating with high (110) orientation and its preparation method. Background Technology

[0002] Tungsten, as the metal with the highest melting point, possesses characteristics such as a low coefficient of thermal expansion, low self-sputtering rate, excellent electron emission performance, stable high-temperature microstructure, and excellent resistance to high-temperature creep. It occupies an important position in the nuclear industry, electronics industry, aerospace, and other fields. For example, tungsten is the only coating material used in the emitter of advanced space thermionic reactor power supplies. The thermionic emission performance of tungsten coatings is closely related to their crystal orientation; the degree of preferred orientation of its (110) crystal plane directly determines the thermoelectric conversion efficiency of the reactor power supply.

[0003] Currently, emitter tungsten coatings are mainly prepared using chemical vapor deposition (CVD), which utilizes hydrogen reduction or thermal decomposition of tungsten halides to grow the tungsten coating. However, most tungsten coatings prepared by CVD under different reaction paths and process conditions are (100) oriented. To increase the proportion of (110) crystal planes in CVD tungsten coatings, patent CN117947505B proposes selecting molybdenum single crystal rods with specific orientations as the substrate material and utilizing the epitaxial growth characteristics of vapor-phase transport coatings to prepare tungsten coatings with a certain (110) orientation. Subsequent electrochemical etching is then performed to expose more (110) crystal planes. However, this method involves extremely high costs for the single crystal substrate and a complex overall process, resulting in a relatively rough coating surface after etching. Patent CN108039497B utilizes the (110) crystal planes of tungsten and... <100> The method features a 45° orientation, creating regular serrated protrusions on a copper substrate. After coating deposition, the outer surface is ground to increase the proportion of tungsten (110) crystal planes. However, this method has limitations in the application of substrate materials, and the machining process requires strict control. Therefore, there is an urgent need to develop a simple and efficient method for preparing tungsten coatings.

[0004] Among various coating preparation technologies, physical vapor deposition (PVD) can precisely control the microstructure and crystal orientation of coatings by controlling the energy and flux of deposited particles. At the same time, the growth of PVD coatings does not depend on the substrate, which has great potential for engineering applications. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a method for preparing a refractory tungsten coating with high (110) orientation, addressing the shortcomings of the prior art. This method directly prepares a tungsten coating with high (110) orientation using arc ion plating, without the need for subsequent processing. The process is simple and low-cost. Moreover, the tungsten coating exhibits significant orientation characteristics, a dense microstructure, a uniform and smooth surface, and strong interfacial bonding, significantly improving the reliability and service life of the tungsten coating application. This solves the problems of insufficient (110) crystal plane ratio in chemical vapor deposition tungsten coatings and the cumbersome and costly nature of existing solutions.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a method for preparing a refractory tungsten coating with high (110) orientation, characterized in that the tungsten coating is prepared by arc ion plating process, exhibiting a (110) preferred orientation and the texture coefficient of the orientation is not less than 2, and the preparation method includes the following steps: Step 1: Matrix pretreatment; Step 2: Inert gas is introduced into the arc ion plating equipment under high vacuum conditions and the pressure is maintained. Then, the substrate is cleaned by bombarding it with a high-energy tungsten ion stream. Step 3: Deposit a transition tungsten coating on the substrate cleaned in Step 2; Step 4: Prepare a tungsten coating with high (110) orientation on the substrate on which the transition tungsten coating was deposited in step 3.

[0007] The above-mentioned method for preparing a refractory tungsten coating with high (110) orientation is characterized in that the (110) preferred orientation includes an equivalent diffraction plane (220). The above-mentioned method for preparing a refractory tungsten coating with high (110) orientation is characterized in that the substrate pretreatment in step one is selected from degreasing, derusting, sandblasting, grinding and polishing; the substrate is selected from molybdenum-based, niobium-based, tantalum-based or tungsten-based refractory alloys, nickel-based or cobalt-based high-temperature alloys, titanium-based alloys or iron-based alloys.

[0008] The method for preparing a refractory tungsten coating with high (110) orientation described above is characterized in that the high vacuum condition in step two is not less than 8 × 10⁻⁶. -3 Pa; the inert gas is Ar and / or He, and the pressure is maintained at 2 Pa to 10 Pa.

[0009] The above-mentioned method for preparing a refractory tungsten coating with high (110) orientation is characterized in that the high-energy tungsten ion flow in step two is generated by an arc discharge of a cathode tungsten target confined by a magnetic field, with an energy of 450eV~800eV, a duty cycle of 15%~60%, and a bombardment cleaning time of 1min~15min.

[0010] The method for preparing a refractory tungsten coating with high (110) orientation described above is characterized in that the magnetic field voltage is 0.5V~30V, the current is 0.5A~20A, and the target surface arc current density is 0.5A / cm². 2 ~2.5A / cm 2 .

[0011] The method for preparing a refractory tungsten coating with high (110) orientation described above is characterized in that the deposition process parameters in step three are: inert gas pressure 2 Pa to 8 Pa, tungsten ion current energy 250 eV to 400 eV, duty cycle 30% to 80%, and target surface arc current density 0.5 A / cm². 2 ~2.5A / cm 2 Magnetic field voltage 0.5V~25V, current 2A~20A, deposition time 5min~40min.

[0012] The method for preparing a refractory tungsten coating with high (110) orientation described above is characterized in that the process parameters for preparing the high (110) orientation tungsten coating in step four are: inert gas pressure 2 Pa to 8 Pa, tungsten ion current energy 30 eV to 230 eV, duty cycle 20% to 80%, and target surface arc current density 0.5 A / cm². 2 ~2.5A / cm 2 The magnetic field voltage is 0.5V~25V, the current is 2A~20A, and the deposition time is set according to the thickness of the tungsten coating; the bonding force between the tungsten coating and the substrate is not less than 50N as tested by the scratch method.

[0013] Meanwhile, the present invention also discloses a refractory tungsten coating with high (110) orientation, characterized in that it is prepared by the above method.

[0014] Compared with the prior art, the present invention has the following advantages: 1. This invention employs an electric arc ion plating method. By optimizing the arc flow density and inert gas pressure on the target surface, it effectively suppresses molten droplets and spark sputtering, achieving stable arc discharge on a high-melting-point tungsten target (approximately 3422°C). Through magnetic field and arc coupling, it effectively controls the uniform movement of the arc spot on the target surface, thereby improving the etching uniformity and utilization rate of the target material. At the same time, it can gather plasma flow and enhance the bombardment effect. By precisely controlling the tungsten ion flow energy and duty cycle, it controls the energy input during the deposition process, thereby driving the tungsten coating to preferentially grow along the (110) crystal plane with low surface energy. Under conditions that do not rely on post-treatment or epitaxial induction, it achieves the direct preparation of a tungsten coating with high (110) orientation.

[0015] 2. Compared with traditional chemical vapor deposition methods, the preparation method of the present invention is simple and environmentally friendly, significantly reducing the coating preparation cost and environmental governance burden, and has the potential to be extended to the preparation of coatings for other refractory metals.

[0016] 3. The tungsten coating prepared by the arc ion plating method of this invention has significant orientation characteristics, dense microstructure, uniform and smooth surface, and strong interfacial bonding, which significantly improves the reliability and service life of tungsten coating applications and provides a new approach for the application of high-performance tungsten coatings in nuclear industry, aerospace and other fields.

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 The images show the surface and cross-sectional morphology of the tungsten coating prepared in Example 1 of this invention.

[0019] Figure 2 The image shows the XRD pattern of the tungsten coating prepared in Example 1 of this invention.

[0020] Figure 3 The images show the surface and cross-sectional morphology of the tungsten coating prepared in Example 2 of this invention.

[0021] Figure 4 The image shows the XRD pattern of the tungsten coating prepared in Example 2 of this invention.

[0022] Figure 5 The images show the surface and cross-sectional morphology of the tungsten coating prepared in Example 3 of this invention.

[0023] Figure 6 The XRD pattern of the tungsten coating prepared in Example 3 of this invention. Detailed Implementation

[0024] Example 1 This embodiment includes the following steps: Step 1: Grind the Mo substrate with a diameter × thickness of φ20mm × 2mm in sequence with 600#, 1000# and 2000# sandpaper, then put it into an ethanol solution for ultrasonic cleaning for 10 minutes, blow it dry and hang it on the sample holder in the arc ion plating equipment that is directly opposite the tungsten target. Step 2: Close the vacuum chamber of the arc ion plating equipment and evacuate to a pressure of 8×10⁻⁶. -3The pressure was increased to 200°C, and Ar gas was introduced through the gas flow meter to maintain the chamber pressure at 5 Pa. Then, the tungsten target arc power supply and magnetic field coil power supply were turned on. The substrate was bombarded and cleaned for 2 minutes using a high-energy tungsten ion current generated by the arc discharge of the magnetically confined cathode tungsten target. The energy of the high-energy tungsten ion current was 500 eV, the duty cycle was 60%, the magnetic field coil voltage was 5.85 V, the current was 15 A, and the target surface arc current density was 0.8 A / cm². 2 ; Step 3: Keeping other conditions unchanged, adjust the tungsten ion flow energy to 300 eV and deposit a transition tungsten coating on the substrate cleaned in Step 2 for 10 min. Step 4: Keeping other conditions unchanged, adjust the tungsten ion flow energy to 100 eV and deposit a high (110) oriented tungsten coating on the substrate where the transition tungsten coating was deposited in step 3 for 2 hours.

[0025] Figure 1 Figure 1 shows the surface and cross-sectional morphology of the tungsten coating prepared in this embodiment, where Figure (a) is the surface morphology and Figure (b) is the cross-sectional morphology. Figure 1 It can be seen that the tungsten coating has a uniform and smooth surface with a roughness of about 102 nm and an average thickness of 3.4 μm. The microstructure is dense and the coating / substrate interface is clear. The interfacial bonding force between the coating and the substrate was tested by the scratch method and reached 65 N.

[0026] Figure 2 The XRD pattern of the tungsten coating prepared in this embodiment is shown below. Figure 2 The tungsten coating shows a (110) preferred orientation. According to the texture coefficient calculation formula, the texture coefficient of the (110) crystal plane (including the equivalent diffraction crystal plane (220)) is 2.52.

[0027] In step two of this embodiment, the inert gas can also be He gas, or a mixture of Ar gas and He gas. Example 2 This embodiment includes the following steps: Step 1: Sandblast the N5 substrate with a diameter × thickness of φ20mm × 2mm, then ultrasonically clean it in an ethanol solution for 20 minutes, blow it dry, and hang it on the sample holder in the arc ion plating equipment that is directly opposite the tungsten target. Step 2: Close the vacuum chamber of the arc ion plating equipment and evacuate to a pressure of 6×10⁻⁶. -3 Pa, heated to 200℃, Ar gas was introduced through the gas flow meter to maintain the chamber pressure at 6Pa, and then the tungsten target arc power supply and magnetic field coil power supply were turned on. The high-energy tungsten ion flow generated by the arc discharge of the cathode tungsten target under magnetic field confinement bombarded and cleaned the substrate for 15 minutes. The energy of the high-energy tungsten ion flow was 800eV, the duty cycle was 15%, the magnetic field coil voltage was 10V, the current was 10A, and the target surface arc current density was 1A / cm. Step 3: Keep the magnetic field coil voltage, current, and target surface arc current density constant, adjust the Ar gas pressure to 4 Pa, the tungsten ion flow energy to 400 eV, and the duty cycle to 30%, and deposit a transition tungsten coating on the substrate cleaned in Step 2 for 15 min. Step 4: Keeping other conditions unchanged, adjust the tungsten ion flow energy to 230 eV and deposit a high (110) oriented tungsten coating on the substrate where the transition tungsten coating was deposited in step 3 for 2 hours.

[0028] Figure 3 Figure 1 shows the surface and cross-sectional morphology of the tungsten coating prepared in this embodiment, where Figure (a) is the surface morphology and Figure (b) is the cross-sectional morphology. Figure 3 It can be seen that the tungsten coating has a uniform and smooth surface with a roughness of about 130 nm and an average thickness of 1.3 μm. The microstructure is dense and the coating / substrate interface is clear. The interfacial bonding force between the coating and the substrate was tested by the scratch method and reached 60 N.

[0029] Figure 4 The XRD pattern of the tungsten coating prepared in this embodiment is shown below. Figure 4 The tungsten coating shows a (110) preferred orientation. According to the texture coefficient calculation formula, the texture coefficient of the (110) crystal plane (including the equivalent diffraction crystal plane (220)) is 3.58.

[0030] Example 3 This embodiment includes the following steps: Step 1: The TC4 substrate with a diameter × thickness of φ20mm × 2mm is degreased, ground and polished in sequence. Then it is placed in an ethanol solution for ultrasonic cleaning for 10 minutes, dried and hung on the sample holder in the arc ion plating equipment facing the tungsten target. Step 2: Close the vacuum chamber of the arc ion plating equipment and evacuate to a pressure of 6×10⁻⁶. -3 The pressure was increased to 200°C, and Ar gas was introduced through the gas flow meter to maintain the chamber pressure at 10 Pa. Then, the tungsten target arc power supply and magnetic field coil power supply were turned on. The substrate was bombarded and cleaned for 15 minutes using a high-energy tungsten ion current generated by the arc discharge of the magnetically confined cathode tungsten target. The energy of the high-energy tungsten ion current was 450 eV, the duty cycle was 40%, the magnetic field coil voltage was 30 V, the current was 20 A, and the target surface arc current density was 2.5 A / cm². 2 ; Step 3: Keep the magnetic field coil current and the target surface arc current density constant, adjust the Ar gas pressure to 8 Pa, the magnetic field coil voltage to 25 V, the energy of the high-energy tungsten ion current to 250 eV, and the duty cycle to 80%. Deposit a transition tungsten coating on the substrate cleaned in Step 2 for 4 min. Step 4: Keeping other conditions unchanged, adjust the tungsten ion flow energy to 50 eV and the duty cycle to 20%, and deposit a high (110) oriented tungsten coating on the substrate where the transition tungsten coating was deposited in step 3 for 2 hours.

[0031] Figure 5 Figure 1 shows the surface and cross-sectional morphology of the tungsten coating prepared in this embodiment, where Figure (a) is the surface morphology and Figure (b) is the cross-sectional morphology. Figure 5 It can be seen that the tungsten coating has a uniform and smooth surface with a roughness of about 65 nm and an average thickness of 7.1 μm. The microstructure is dense and the coating / substrate interface is clear. The interfacial bonding force between the coating and the substrate was tested by the scratch method and reached 68 N.

[0032] Figure 6 The XRD pattern of the tungsten coating prepared in this embodiment is shown below. Figure 6 The tungsten coating shows a (110) preferred orientation. According to the texture coefficient calculation formula, the texture coefficient of the (110) crystal plane (including the equivalent diffraction crystal plane (220)) is 3.04.

[0033] Example 4 This embodiment includes the following steps: Step 1: The TC4 substrate with a diameter × thickness of φ20mm × 2mm is subjected to rust removal and sandblasting treatment in sequence. Then, it is placed in an ethanol solution for ultrasonic cleaning for 30 minutes, dried, and then suspended on the sample rack in the arc ion plating equipment facing the tungsten target. Step 2: Close the vacuum chamber of the arc ion plating equipment and evacuate to a pressure of 8×10⁻⁶. -3 The pressure was increased to 200°C, and Ar gas was introduced through the gas flow meter to maintain the chamber pressure at 2 Pa. Then, the tungsten target arc power supply and magnetic field coil power supply were turned on. The high-energy tungsten ion current generated by the arc discharge of the cathode tungsten target under magnetic confinement was used to bombard and clean the substrate for 1 minute. The energy of the high-energy tungsten ion current was 800 eV, the duty cycle was 15%, the magnetic field coil voltage was 0.5 V, the current was 0.5 A, and the target surface arc current density was 0.5 A / cm². 2 ; Step 3: Keep the Ar gas pressure, magnetic field coil current and target surface arc current density constant, adjust the magnetic field coil current to 2A, tungsten ion current energy to 250eV, and duty cycle to 80%, and deposit a transition tungsten coating on the substrate cleaned in step 2 for 5 minutes. Step 4: Keeping other conditions unchanged, adjust the tungsten ion flow energy to 30 eV and deposit a high (110) oriented tungsten coating on the substrate where the transition tungsten coating was deposited in step 3 for 2 hours.

[0034] Upon testing, the tungsten coating prepared in this embodiment has a uniform and smooth surface with a roughness of approximately 120 nm. The average thickness of the tungsten coating is 7.7 μm, the microstructure is dense, and the coating / substrate interface is clear. The interfacial bonding force between the coating and the substrate was tested by the scratch method and reached 52 N. The tungsten coating exhibits a (110) preferred orientation. According to the texture coefficient calculation formula, the texture coefficient of the (110) crystal plane (including the equivalent diffraction crystal plane (220)) is 2.25.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a refractory tungsten coating with high (110) orientation, characterized in that, The tungsten coating is prepared by arc ion plating and exhibits a (110) preferred orientation with a texture coefficient of not less than 2. The preparation method includes the following steps: Step 1: Matrix pretreatment; Step 2: Inert gas is introduced into the arc ion plating equipment under high vacuum conditions and the pressure is maintained. Then, the substrate is cleaned by bombarding it with a high-energy tungsten ion stream. Step 3: Deposit a transition tungsten coating on the substrate cleaned in Step 2; Step 4: Prepare a tungsten coating with high (110) orientation on the substrate on which the transition tungsten coating was deposited in step 3.

2. The method for preparing a refractory tungsten coating with high (110) orientation according to claim 1, characterized in that, The preferred orientation (110) includes the equivalent diffraction plane (220).

3. The method for preparing a refractory tungsten coating with high (110) orientation according to claim 1, characterized in that, The substrate pretreatment in step one is selected from degreasing, rust removal, sandblasting, grinding and polishing; the substrate is selected from molybdenum-based, niobium-based, tantalum-based or tungsten-based refractory alloys, nickel-based or cobalt-based high-temperature alloys, titanium-based alloys or iron-based alloys.

4. The method for preparing a refractory tungsten coating with high (110) orientation according to claim 1, characterized in that, The high vacuum condition mentioned in step two is not less than 8 × 10⁻⁶. -3 Pa; the inert gas is Ar and / or He, and the pressure is maintained at 2 Pa to 10 Pa.

5. The method for preparing a refractory tungsten coating with high (110) orientation according to claim 1, characterized in that, The high-energy tungsten ion flow mentioned in step two is generated by the arc discharge of the cathode tungsten target confined by a magnetic field, with an energy of 450eV~800eV, a duty cycle of 15%~60%, and a bombardment cleaning time of 1min~15min.

6. The method for preparing a refractory tungsten coating with high (110) orientation according to claim 5, characterized in that, The magnetic field voltage is 0.5V~30V, the current is 0.5A~20A, and the target surface arc current density is 0.5A / cm². 2 ~2.5A / cm 2 .

7. The method for preparing a refractory tungsten coating with high (110) orientation according to claim 1, characterized in that, The deposition process parameters described in step three are: inert gas pressure 2 Pa to 8 Pa, tungsten ion current energy 250 eV to 400 eV, duty cycle 30% to 80%, and target surface arc current density 0.5 A / cm². 2 ~2.5A / cm 2 Magnetic field voltage 0.5V~25V, current 2A~20A, deposition time 5min~40min.

8. The method for preparing a refractory tungsten coating with high (110) orientation according to claim 1, characterized in that, The process parameters for preparing the highly (110) oriented tungsten coating in step four are: inert gas pressure 2 Pa~8 Pa, tungsten ion current energy 30 eV~230 eV, duty cycle 20%~80%, and target surface arc current density 0.5 A / cm². 2 ~2.5A / cm 2 The magnetic field voltage is 0.5V~25V, the current is 2A~20A, and the deposition time is set according to the thickness of the tungsten coating; the bonding force between the tungsten coating and the substrate is not less than 50N as tested by the scratch method.

9. A refractory tungsten coating with high (110) orientation, characterized in that, Prepared by the method described in any one of claims 1 to 8.

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