Method for coating substrate with tetragonal vanadium nitride

Abstract

The invention relates to a method for coating a substrate with tetragonal vanadium nitride by means of high-power pulsed magnetron sputtering. The invention also relates to a substrate coated with at least one layer of tetragonal vanadium nitride. The method according to the invention is particularly useful in the fields of electronic components, transducers of sensors, optics, machinery and micromachinery, decoration and protection of surfaces, motor vehicles, aviation or aerospace.

Description

Technical Field

[0001] This invention relates to the general field of producing thin layers, and more specifically to the metallization of various substrates. More specifically, this invention relates to a method for coating a substrate with tetragonal vanadium nitride by means of high-power pulsed magnetron sputtering, and a substrate coated with at least one layer of tetragonal vanadium nitride.

[0002] The method and substrate of the present invention are particularly useful in the fields of electronic components, transducers for sensors, optics, photonics, mechanics and micromechanics, decorative and protective surfaces, motor vehicles, and aviation or aerospace. Background Technology

[0003] To improve the properties of metals, composites, polymers or other materials, especially in terms of corrosion resistance and / or abrasion resistance, the substrate is coated with a protective layer.

[0004] The coating, commonly known as hard chrome, possesses numerous physical, chemical, and abrasion-resistant properties in a variety of environments, making it one of the most widely used multi-purpose coatings applied in various industrial sectors (machining, land, aerospace, and space transportation). Hard chrome is produced by involving the presence of hexavalent chromium (Cr). 6+ Hexavalent chromium is obtained through electrolytic chromium deposition. However, hexavalent chromium possesses carcinogenic, mutagenic, and reproductive toxic (CMR) properties, which are incompatible with the REACH Directive (an EU regulation adopted to better protect human health and the environment from risks associated with chemicals, while enhancing the competitiveness of the EU chemical industry). Furthermore, hard chromium exhibits a variety of properties, making it difficult to match with a single, universal solution.

[0005] The transition metal nitride family has many similar structural and functional properties, which can make it a substitute for hard chromium for certain applications.

[0006] The REACH directive strictly prohibits the use of hexavalent chromium (Cr) during electrolytic chromium formation or hard chromium deposition. 6+ This led the inventors of this invention to study transition metal nitrides, including vanadium nitride, in order to mimic the structural and functional properties of hard chromium. Therefore, vanadium nitride was explored and its tribological properties were investigated. Hardness, resistivity, thermal conductivity, and other properties are all interesting and worthy of further development, which aligns with the needs of related fields.

[0007] Researchers have studied vanadium nitride. Different crystal phases of vanadium nitride were studied from scratch (…). ab initio )Calculations are used to predict.

[0008] In 1988, F. Kubel et al., Physical Review B, 1988, vol. 38, no. 18, 12908-12912, obtained a tetragonal phase of vanadium nitride at a transformation temperature of 205 K (-68 °C). This metastable phase is unstable at temperatures above 205 K (-68 °C). More importantly, this material is not a coating, but a powder. Studies of metastable vanadium nitride phases that do not exist in the VN binary phase diagram, regardless of temperature (>0 °C) and nitrogen stoichiometry, have been conducted using ab initio calculations to understand the stability of these phases.

[0009] Vanadium nitride has also been studied as a hardening and reinforcing material for steel.

[0010] AB Mei et al. (Physical Review B, vol. 91, no. 5, 054101) developed cubic vanadium nitride thin films using direct current magnetron sputtering (dcMS). The authors also used ab initio molecular dynamics calculations to investigate the transition from the cubic to the tetragonal phase at 205 K, in order to correlate these with analyses performed at temperatures below 205 K using X-ray diffraction and transmission electron microscopy.

[0011] Therefore, there is indeed a need for an alternative coating to hard chrome that has at least equivalent physical, chemical, and abrasion-resistant properties.

[0012] In particular, there is a need for an alternative coating to hard chrome that has at least equivalent physical, chemical and abrasion-resistant properties and is stable at ambient temperatures (20±5°C).

[0013] In particular, there is a genuine need for an alternative coating to hard chrome as described above, which is compliant with the REACH Directive and is simple, effective, and economical to apply, thus having industrial significance. Summary of the Invention

[0014] This invention relates to a method for coating a substrate with tetragonal vanadium nitride using high-power pulsed magnetron sputtering, characterized in that the substrate coating is performed in a deposition chamber, in which vanadium is in the form of a solid vanadium target and faces the substrate to be coated. Coating method used - Under pressures between 0.1 and 20 Pa, and - At temperatures between room temperature (20±5℃) and 900℃, and - In an atmosphere containing a mixture of nitrogen and argon, wherein the nitrogen content in the mixture is between 5% and 99%, During coating deposition, the polarization of the target is controlled by superimposing a DC polarization with a potential (Vc) greater than 0 and less than or equal to -900V and a pulsed polarization with a potential (Vp) between -1200V and -100V.

[0015] The polarization of the target can be maintained from 10µs to 900µs.

[0016] The polarization of the target material can be achieved at frequencies between 100 Hz and 9000 Hz.

[0017] An apparatus for deposition by high-power pulsed magnetron sputtering is perfectly suited for carrying out the method of the present invention, the apparatus comprising: Figure 1 The sedimentation chamber is shown in the figure and described in detail in application FR 3 097 237.

[0018] As already noted, the tetragonal phase of vanadium nitride is predicted by calculation to be a metastable phase, but it cannot be stable or observed at room temperature (20 ± 5 °C). By using and controlling the parameters of the high-power pulsed magnetron sputtering (HiPIMS) method, the inventors have successfully obtained and stabilized the tetragonal phase of vanadium nitride at room temperature (20 ± 5 °C) and characterized it, which has never been done before.

[0019] In high-power pulsed magnetron sputtering (HiPIMS) technology, the target is specially polarized to form a tetragonal vanadium nitride coating. In terms of its physical, chemical and abrasion-resistant properties in various environments, tetragonal vanadium nitride is a satisfactory alternative to hard chrome.

[0020] The present invention also relates to a substrate coated with at least one layer of tetragonal vanadium nitride.

[0021] This method can coat a substrate with one or more tetragonal vanadium nitride thin layers, depending on the selected operating conditions.

[0022] When a substrate is coated with several layers, these layers can be detected based on their microstructure. In HiPIMS, the layers will be dense, and it is possible to distinguish between two layers, for example, by scanning electron microscopy (SEM). The substrate can also be coated with one or more tetragonal vanadium nitride thin films and / or one or more layers of different materials and / or layers of vanadium nitride of different phases.

[0023] The high-power pulsed magnetron sputtering (HiPIMS) technology implemented by the method of this invention enables the development of dense, uniform, and defect-free coatings with perfectly controlled microstructure and chemical composition. The method of this invention adds new, modifiable parameters, such as pulse intensity, pulse duration, and frequency, to those commonly used for magnetron sputtering deposition optimization, resulting in the stabilization of new metastable crystalline phases.

[0024] Therefore, the method of the present invention is of particular interest because it uses high-power pulsed magnetron sputtering (HiPIMS) to stabilize the tetragonal vanadium nitride phase at room temperature (20 ± 5 °C). This phase, which is not predicted in the phase diagram and has only been observed experimentally once in powder during the low-temperature (205 K) phase transition of the cubic phase, cannot be characterized at room temperature (20 ± 5 °C). Attached Figure Description

[0025] Other features and advantages of the invention will become apparent from the following detailed description and accompanying drawings.

[0026] Figure 1 A deposition chamber is schematically shown in which a method for coating a substrate with tetragonal vanadium nitride by means of high-power pulsed magnetron sputtering, according to an embodiment of the present invention, is performed.

[0027] Figure 2 The PANalytical X'Pert Pro X-ray diffraction pattern of a 316L stainless steel substrate coated with a tetragonal vanadium nitride layer according to the method of the present invention is shown. The substrate measures 2.5 cm x 2.5 cm and has a thickness of 500 μm. Starting from the bottom, the first diffraction pattern is the diffraction pattern of the bare substrate, i.e., the part on which the coating is to be applied. The middle and top diffraction patterns are diffraction patterns of two tetragonal VN depositions prepared one month apart. By comparing the diffraction peaks and angles, the reproducibility of the method of the present invention can be observed.

[0028] X-rays penetrate a deeper than the coating into the sample (i.e., substrate + coating). Therefore, the diffraction pattern of the sample (middle and top diffraction patterns) shows peaks corresponding to the coating and peaks corresponding to the substrate. The diffraction pattern of the uncoated metal substrate allows for the identification of both substrate and coating peaks on the sample's diffraction pattern. Detailed Implementation

[0029] This invention relates to a method for coating a substrate with tetragonal vanadium nitride using high-power pulsed magnetron sputtering, characterized in that the coating of the substrate is performed in a deposition chamber, in which vanadium is in the form of a solid vanadium target and faces the substrate to be coated. Coating method used - Under pressures between 0.1 Pa and 20 Pa, and - At temperatures between room temperature (20±5℃) and 900℃, and - In an atmosphere containing a mixture of nitrogen and argon, wherein the nitrogen content in the mixture is between 5% and 99%, During coating deposition, the polarization of the target is controlled by superimposing a DC polarization with a potential (Vc) greater than 0 and less than or equal to -900V and a pulsed polarization with a potential (Vp) between -1200V and -100V.

[0030] In the context of this invention, the term "solid vanadium target" refers to a vanadium target with a purity of at least 99.5% by mass of vanadium.

[0031] The polarization of the target material can be achieved at frequencies between 100 Hz and 9000 Hz.

[0032] In one embodiment, the coating method is performed under a pressure of 1 Pa.

[0033] Although the atmosphere containing a mixture of nitrogen and argon as described above is preferred, the coating method of the present invention can also be carried out in a nitrogen atmosphere mixed with other plasma-forming gases known to those skilled in the art.

[0034] In the context of this invention, the expression "between ... and ..." should be understood to include endpoint values.

[0035] In the context of this invention, the expression "greater than... or less than..." should be understood to exclude endpoint values.

[0036] The coating is in the form of a thin layer.

[0037] Thin layers with less than 10 -4 millibars, preferably less than 10 -6 Vanadium is produced in a low-pressure deposition chamber at millibars. Vanadium exists in the deposition chamber as a solid vanadium target, facing the substrate to be coated. The target is the cathode. The substrate to be coated forms the anode.

[0038] Throughout the deposition process, the substrate is maintained at a temperature between room temperature (20±5℃) and 900℃.

[0039] During deposition, the plasma-gas mixture as described above is introduced into the deposition chamber. The target material is in contact with a cooled cathode coupled to a permanent magnet, while the substrate is grounded or optionally positively biased or held at a floating potential. A potential difference is applied between the two electrodes to achieve the breakdown voltage of the gas or gas mixture, thereby initiating a low-pressure plasma, i.e., at 1.10 during deposition. -4 Pressures between 1 and 1 millibar, especially 10 -3 Between 5.10 and 1 millibar.

[0040] In addition to a DC electric field (from 0 to -900V in one embodiment, greater than 0 and less than or equal to -900V, or from -100 to -600V in another embodiment), the generator also transmits a high-voltage pulsed current. In another embodiment, the voltage used is between -1200 and -100V, or between -1000 and -500V. In another embodiment, the duration of the voltage peak is maintained between 10 and 900μs or between 50 and 400μs, and in yet another embodiment, the frequency of the voltage peak is maintained between 100 and 9000Hz or between 100 and 5000Hz.

[0041] As previously mentioned, the coating method is carried out in an atmosphere containing nitrogen mixed with argon, with a nitrogen content between 5% and 99%.

[0042] The thickness of each tetragonal vanadium nitride / coating deposited on the substrate can be between 5 nm and 15 μm. When the coating is in the form of multiple layers, the thickness of the multiple layers can be, for example, between 10 nm and 100 μm.

[0043] The diffraction pattern obtained using a PANalytical X'Pert Pro X-ray diffractometer on a 2.5 cm x 2.5 cm, 500 µm thick 316L stainless steel substrate coated with a stable tetragonal vanadium nitride layer and obtained by the method of this invention clearly shows the following: Figure 2 The characteristic peaks of tetragonal vanadium nitride shown in the figure confirm that the parameters of the method of the present invention described above can be used to obtain a 1 μm thick coating by means of the method of the present invention based on using HiPIMS technology to stabilize the tetragonal phase of vanadium nitride.

[0044] The present invention also relates to a substrate coated with at least one layer of tetragonal vanadium nitride.

[0045] This method can be used to coat a wide variety of substrates, depending on the application, as long as they can withstand temperatures of 40°C.

[0046] The substrate can be metal, ceramic, composite material, elastomer, glass, metallic glass, plastic or fabric.

[0047] In one embodiment, the substrate is stainless steel, such as 316L stainless steel.

[0048] In one embodiment, the substrate is an aircraft component, such as an aircraft landing gear component or an aircraft engine turbine component.

[0049] In one embodiment, the substrate is a gas turbine or marine turbine component.

[0050] The method of the present invention is of particular interest in the fields of electronic components, transducers for sensors, optics, photonics (i.e., lasers, light-emitting diodes, optical fibers, optical modulators, optical amplifiers or photonic crystals, lenses, prisms and gratings), mechanics and micromechanics, decorative and protective surfaces, motor vehicles, and aviation or aerospace.

[0051] Therefore, another object of the present invention is to use the method of the present invention for manufacturing electronic components, transducers for sensors, optical components, mechanical and micromechanical components, components for decorating and protecting surfaces, and components for use in the automotive, aerospace or space industries.

[0052] Example The coating was deposited on a 316L stainless steel substrate. The substrate was first cleaned by immersion in a beaker containing boiling isopropanol. The baseline vacuum of the chamber achieved prior to deposition was 3.0E-6T. Plasma was initiated at 5 Pa in an argon / nitrogen mixture. The applied voltage and current were -1000V and 200mA, respectively, with a DC background of -50V and 10mA. The frequency and width of the high-power pulse (HiPIMS) were 100Hz and 200µs, respectively. The pressure was then reduced to 1 Pa. The chamber containing the Ar / N2 mixture was preheated to 400°C at 1 Pa, 40 sccm of argon, and 5 sccm of nitrogen. The Ar / N2 mixture can be described by the percentage of N2 in the total volume of the gaseous [Ar+N2]. It is 5 / (40+5) = 11%. However, a ratio can be a good way to describe this method (N2 ratio = N2 flow rate / Ar flow rate). The nitrogen ratio was 12.5. In this method, the plasma is stabilized at this point for 15 minutes, and then the substrate is faced with a vanadium target (purity greater than or equal to 99.9%). Deposition lasts for 3 hours.

[0053] The coating thickness was determined by scanning electron microscopy (SEM JEOL 6360A), and the crystal structure was determined by X-ray diffraction (DRX PANalytical X'Pert Pro).

Claims

1. A method for coating a substrate with tetragonal vanadium nitride using high-power pulsed magnetron sputtering, characterized in that, The coating of the substrate is performed in a deposition chamber, in which vanadium is in the form of a solid vanadium target and faces the substrate to be coated. Coating method used - Under pressures between 0.1 Pa and 20 Pa, and - At temperatures between room temperature (20±5℃) and 900℃, and - In an atmosphere containing a mixture of nitrogen and argon, wherein the nitrogen content in the mixture is between 5% and 99%, During coating deposition, the polarization of the target is controlled by superimposing a DC polarization with a potential (Vc) greater than 0 and less than or equal to -900V and a pulsed polarization with a potential (Vp) between -1200V and -100V.

2. The method according to claim 1, characterized in that, The method is carried out under a pressure of 1 Pa.

3. The method according to any one of claims 1 or 2, characterized in that, The polarization of the target material is achieved at frequencies between 100 Hz and 9000 Hz.

4. The method according to any one of claims 1 to 3, characterized in that, During coating deposition, the polarization of the target is controlled by applying a superposition of DC polarizations with a potential (Vc) between -100V and -600V.

5. The method according to any one of claims 1 to 4, characterized in that, During coating deposition, the polarization of the target is controlled by superimposing a DC polarization of the potential (Vc) as described in claims 1 and 4 and a pulsed polarization of a potential (Vp) having a pulse between -1000V and -500V.

6. The method according to any one of claims 1 to 5, characterized in that, The substrate is coated with one or more tetragonal vanadium nitride thin layers, each with a thickness between 5 nm and 15 µm.

7. The method according to claim 6, characterized in that, When the coating is in the form of multiple layers, the thickness of the multiple layers is between 10µm and 100µm.

8. The method according to any one of claims 1 to 7, characterized in that, The vanadium is in the form of a solid vanadium sputtering target with a purity of at least 99.5% by mass.

9. Use of the method according to any one of claims 1 to 8 for the manufacture of electronic components, transducers for sensors, optical components, mechanical and micromechanical components, components for decorating and protecting surfaces, and components for the automotive, aerospace, or space industries.

10. A substrate coated with at least one layer of tetragonal vanadium nitride by the method of any one of claims 1 to 8.

11. The substrate according to claim 10, characterized in that, The substrate is -Aircraft landing gear components, or - Aircraft engine turbine components, or - Gas turbine or marine turbine components.

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