A tough molybdenum nitride-based protective coating and a preparation method and application thereof

Abstract

The application discloses a toughened molybdenum nitride-based protective coating and a preparation method and application thereof, and belongs to the technical field of protective coatings. The toughened molybdenum nitride-based protective coating comprises a MoXN layer; according to atomic percentage, the MoXN layer comprises 60% to 75% of Mo and 7% to 15% of X, and the balance is N; wherein X comprises at least one element in Ti, Zr, V and Nb; the MoXN layer has a B1 face-centered cubic phase structure; and the MoXN layer has a nanocrystalline structure, and the nanocrystalline structure has lattice distortion and dislocations. The MoXN layer has the synergistic hardening effect of fine grain, lattice distortion and dislocation, and the dislocation can provide plastic deformation capacity and increase the toughness of the coating, so that the toughened molybdenum nitride-based protective coating has the super-high hardness of a ceramic phase and the good toughness of a metal, and has a good protective effect.

Description

Technical Field

[0001] This invention relates to the field of protective coating technology, and more specifically, to a tough molybdenum nitride-based protective coating, its preparation method, and its application. Background Technology

[0002] Metal nitride ceramic phases have high hardness, excellent chemical stability and high temperature resistance, making them a preferred material for protective coatings. However, due to their lack of necessary plastic deformation ability and weak crack resistance, they are prone to sudden fracture failure when subjected to impact and alternating loads, which may even cause collateral damage to the substrate and reduce the substrate's lifespan. This is a major pain point for ceramic protective coatings.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a tough molybdenum nitride-based protective coating, its preparation method, and its application, so as to solve or improve the above-mentioned technical problems.

[0005] This invention can be implemented as follows:

[0006] In a first aspect, the present invention provides a tough molybdenum nitride-based protective coating, the tough molybdenum nitride-based protective coating comprising a MoXN layer;

[0007] The MoXN layer comprises 60% to 75% Mo and 7% to 15% X by atomic percentage, with the balance being N; wherein X includes at least one element selected from Ti, Zr, V and Nb.

[0008] The MoXN layer has a B1 face-centered cubic phase structure and a nanocrystalline structure with lattice distortion and high-density dislocations.

[0009] In an optional embodiment, the tough molybdenum nitride-based protective coating further includes a MoQ transition layer, wherein a MoXN layer is disposed on the surface of the MoQ transition layer; wherein Q includes at least one element selected from Ti, Zr, V and Nb.

[0010] In an optional implementation, the thickness of the MoQ transition layer does not exceed 5 μm.

[0011] In an optional implementation, the MoXN layer also has at least one of the following characteristics:

[0012] Feature 1: The MoXN layer lattice contains anion vacancies; preferably, the proportion of anion vacancies in the MoXN layer lattice is 50%~64% by atomic percentage.

[0013] Feature 2: The dislocation density in the MoXN layer is not less than 4.2 × 10⁻⁶. 11 cm -2The preferred value is 4.2×10 11 cm -2 ~7.5×10 11 cm -2 ;

[0014] Feature 3: The nanocrystalline structure is a nanocolumnar crystal structure; preferably, the average grain size of the nanocolumnar crystal structure is 14nm~60nm, more preferably 20nm~40nm;

[0015] Feature 4: The thickness of the MoXN layer does not exceed 10 μm; preferably, the thickness of the MoXN layer is 2 μm to 10 μm;

[0016] Feature 5: The hardness of the tough molybdenum nitride-based protective coating is not less than 35 GPa, preferably 35 GPa to 45 GPa;

[0017] Feature 6: The tough molybdenum nitride-based protective coating shows no surface cracks after being pressed in with a triangular pyramid indenter and a load of 200mN.

[0018] In a second aspect, the present invention provides a method for preparing a tough molybdenum nitride-based protective coating as described in any of the foregoing embodiments, comprising the following steps: depositing a MoXN layer on the surface of a substrate.

[0019] In an optional implementation, the substrate is cleaned before depositing the MoXN layer;

[0020] Cleaning is performed using ion etching.

[0021] Ion etching conditions include: vacuum pressure not exceeding 5 × 10⁻⁶. -3 The argon gas pressure is 0.1 Pa to 0.3 Pa, the furnace temperature is 150℃ to 350℃, the ion source current is 0.1 A to 0.3 A, the substrate bias voltage is -100 V to -300 V, and the time is 20 min to 40 min.

[0022] In an optional implementation, a high-energy deposition method is used to prepare the MoXN layer;

[0023] High-energy deposition methods include high-power magnetron sputtering or arc ion plating.

[0024] In an optional implementation, the MoXN layer is prepared by high-power magnetron sputtering;

[0025] The high-power magnetron sputtering conditions include: sputtering cathode power of 3.5kW~6.0kW, argon flow rate of 60sccm~100sccm, nitrogen flow rate of 30sccm~60sccm, gas pressure of 0.3Pa~1.2Pa, bias voltage of -80V to -150V, deposition temperature of 150℃~350℃, and deposition time of 60min~300min.

[0026] In an optional embodiment, when the coating includes a MoQ transition layer, the MoQ transition layer is first deposited on the substrate surface, and then a MoXN layer is deposited on the surface of the MoQ transition layer.

[0027] The MoQ transition layer was prepared by low-energy deposition or high-energy deposition.

[0028] High-energy deposition methods include high-power magnetron sputtering or arc ion plating; low-energy deposition methods include DC magnetron sputtering.

[0029] In an optional implementation, the MoQ transition layer is prepared by DC magnetron sputtering;

[0030] DC magnetron sputtering conditions include: sputtering cathode power of 3.0kW~5.0kW, argon flow rate of 80sccm~150sccm, gas pressure of 0.3Pa~1.2Pa, bias voltage of -80V to -150V, and deposition time of no more than 20min.

[0031] Thirdly, the present invention provides an application of a tough molybdenum nitride-based protective coating as described in any of the foregoing embodiments, wherein the tough molybdenum nitride-based protective coating is used in moving parts, cutting tools or molds.

[0032] In an optional implementation, the moving parts of the equipment include at least one of electronic equipment moving parts and aerospace equipment moving parts.

[0033] In an alternative implementation, the cutting tool includes a high-speed cutting tool.

[0034] In an optional implementation, the mold includes cold-working and hot-working molds.

[0035] The beneficial effects of this invention include:

[0036] The tough molybdenum nitride-based protective coating provided by this invention combines the advantages of high hardness and high toughness. The MoXN layer exhibits a covalent-metallic hybrid bonding mechanism and an ultrafine nanocrystalline structure. Simultaneously, the nanocrystalline lattice contains numerous lattice distortions, inducing a large number of dislocations within the lattice. This results in the MoXN coating prepared by this invention possessing a synergistic hardening effect from fine grains, lattice distortion, and dislocations. The dislocations also simultaneously provide plastic deformation capability, increasing the coating's toughness. Furthermore, the preparation method of the tough molybdenum nitride-based protective coating provided by this invention is simple, efficient, environmentally friendly, and uses low-cost materials, showing promising application prospects in the field of wear-resistant protection. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 The XRD phase diagrams of the MoTiN layers obtained in Examples 1, 2 and Comparative Example 1 of this invention are shown below.

[0039] Figure 2 This is an electron energy spectrum (EDS) chemical composition diagram of the MoTiN layer prepared in Example 1 of the present invention;

[0040] Figure 3 This is a bright-field TEM image of the MoTiN layer obtained in Example 1 of the present invention;

[0041] Figure 4 This is a high-resolution lattice fringe image inside the MoTiN layer grains obtained in Example 1 of the present invention;

[0042] Figure 5 for Figure 4 The corresponding FFT single-crystal electron diffraction pattern;

[0043] Figure 6 This is a topography image of the MoTiN layer prepared in Example 1 of the present invention observed in a dual-beam bright-field mode with a g vector of

[111] . The upper left corner region is the corresponding electron diffraction, and the direction of the red arrow in this region is the direction of the g vector.

[0044] Figure 7 The surface morphology of the indentation under a 200mN triangular pyramid indenter is shown for the protective coating prepared in Example 1 of this invention.

[0045] Figure 8 The surface morphology of the protective coating prepared in Comparative Example 1 of this invention is shown in the indentation under a 200mN triangular pyramid indenter. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0047] The following is a detailed description of the tough molybdenum nitride-based protective coating, its preparation method, and its application provided by the present invention.

[0048] The inventors, through long-term research, proposed that the fundamental reason for the high brittleness of ceramic phases is that the dislocation formation energy of covalent bond crystals is extremely high, and the crystal lattice containing covalent bonds is difficult to accommodate dislocations, thus lacking a plastic deformation carrier, and therefore it is difficult to undergo synergistic deformation with the tough metal matrix.

[0049] Based on this, the present invention creatively employs a MoN-based ceramic composition design, utilizing the poor affinity between N and Mo in FCC-MoN. 0.5 The medium-solid-solution of Ti, Zr, V, or Nb, which have larger atomic radii and are more compatible with N, produces more severe lattice distortion. At the same time, high-energy non-equilibrium deposition is used to further increase N vacancies through the bombardment and back sputtering effect of high-energy heavy element Mo, and to further introduce high-density distortion and dislocations into the coating, providing a large number of plastic deformation carriers, significantly improving its plastic deformation capacity and introducing work hardening effect, effectively improving hardness and toughness.

[0050] Specifically, the tough molybdenum nitride-based protective coating provided by the present invention includes a MoXN layer.

[0051] On an atomic percentage basis, the MoXN layer comprises 60%–75% Mo and 7%–15% X, with the balance being N. X includes at least one element selected from Ti, Zr, V, and Nb.

[0052] In some alternative implementations, the amount of Mo contained in the MoXN layer can be 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 67%, 70%, 71%, 72%, 73%, 74% or 75%, or other values ​​in the range of 60% to 75%.

[0053] The amount of X contained in the MoXN layer can be 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%, or other values ​​within the range of 7% to 15%.

[0054] It should be noted that in this invention, X is specifically selected from at least one element chosen from Ti, Zr, V, and Nb. In some typical embodiments, X includes at least Ti. If the MoXN layer contains too little X, it is not conducive to the formation of a stable Bi single-phase structure and large lattice distortion; if the MoXN layer contains too much X, it is not conducive to the formation of anion vacancies and high-density dislocations.

[0055] In this invention, the MoXN layer has a B1 face-centered cubic phase structure and a nanocrystalline structure, which contains lattice distortion and dislocations.

[0056] Among them, "B1" is a type of designation in structural physics (defined by the Strukturbericht crystal structure database), in which cations and anions each form a face-centered cubic (FCC) lattice, and a stable ionic bond structure is formed by interleaving.

[0057] The MoXN layer lattice contains anion vacancies. In some optional embodiments, the proportion of anion vacancies in the MoXN layer lattice, by atomic percentage, can be 50% to 64%, such as 50%, 52%, 55%, 58%, 60%, 62%, or 64%, or other values ​​within the range of 50% to 64%. Anion vacancies within this range are conducive to introducing severe lattice distortion and high-density dislocations.

[0058] In some alternative implementations, the dislocation density in the MoXN layer is not less than 4.2 × 10⁻⁶. 11 cm -2 For example, it can be 4.2 × 10 11 cm -2 ~7.5×10 11 cm -2 .

[0059] In some optional embodiments, the nanocrystalline structure in the MoXN layer is a nanocolumnar structure. Preferably, the MoXN layer has a continuous and dense nanocolumnar structure. The average grain size of the aforementioned nanocolumnar structure is 14 nm to 60 nm, for example, 20 nm to 40 nm.

[0060] In some alternative embodiments, the thickness of the MoXN layer does not exceed 10 μm. Preferably, the thickness of the MoXN layer can be 2 μm to 10 μm, such as 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm.

[0061] If the MoXN layer is too thin, it is easily worn during use and cannot effectively provide protection; if the MoXN layer is too thick, its internal stress may be too high, leading to a reduction in bonding strength.

[0062] Continuing from the above, in the MoXN layer provided by this invention, Mo serves as the principal element of the metal sublattice, and X (at least one of Ti, Zr, V, and Nb) serves as the solute atom. Due to the poor affinity of Mo for N, the stoichiometry of the Mo-N phase with a stable face-centered cubic structure is MoN. 0.5 Its crystal lattice naturally contains 50% N vacancies. The role of Ti, Zr, V, and Nb as solid solution elements is twofold: firstly, their larger atomic radii enhance lattice distortion; secondly, their better affinity for N, causing N to more readily bind with Ti, inducing localized N atom segregation in the lattice and further amplifying lattice distortion. Furthermore, the backsplashing effect generated by heavy element Mo bombardment during sputtering deposition further reduces N content, increases N vacancies, and simultaneously reduces grain size; the increase in N vacancies relatively leads to an increase in the proportion of metallic bonds. The simultaneous presence of high-concentration point defects and severe lattice distortion induces the formation of high-density dislocations.

[0063] Furthermore, the tough molybdenum nitride-based protective coating provided by the present invention may also include a MoQ transition layer to provide a mechanical transition between the substrate and the MoXN layer. That is, the tough molybdenum nitride-based protective coating of the present invention may or may not contain a MoQ transition layer.

[0064] When the tough molybdenum nitride-based protective coating contains a MoQ layer, a MoXN layer is disposed on the surface of the MoQ transition layer. Here, Q includes at least one element selected from Ti, Zr, V, and Nb.

[0065] In some alternative implementations, the X element in the MoXN layer is the same as the Q element in the MoQ transition layer; in other alternative implementations, the X element in the MoXN layer is different from the Q element in the MoQ transition layer, but both are selected from Ti, Zr, V and Nb.

[0066] In some optional embodiments, the thickness of the MoQ transition layer does not exceed 5 μm, such as 5 μm, 4.5 μm, 4 μm, 3.5 μm, 3 μm, 2.5 μm, 2 μm, 1.5 μm, 1 μm, or 0.5 μm, or other values ​​not exceeding 5 μm. Further, the thickness of the MoQ transition layer does not exceed 0.5 μm.

[0067] If the thickness of the MoQ transition layer exceeds 5μm, it can easily lead to a decrease in the hardness of the tough molybdenum nitride-based protective coating.

[0068] In some optional embodiments, the hardness of the tough molybdenum nitride-based protective coating is not less than 35 GPa, for example, it can be 35 GPa to 45 GPa.

[0069] In some alternative implementations, the tough molybdenum nitride-based protective coating shows no surface cracks after being pressed in with a triangular pyramid indenter under a load of 200 mN.

[0070] Continuing from the above, the tough molybdenum nitride-based protective coating provided by this invention has a chemical bond composition that combines strong covalent bonds (such as the covalent portions of Mo-N and Ti-N bonds) and metallic bonds (such as the metallic portions of Mo-N and Ti-N bonds and Mo-Ti metallic bonds). At the same time, the extremely fine nanocrystals and high-density dislocations produce significant grain refinement and dislocation strengthening effects. The high-density dislocations also ensure excellent plastic deformation ability, giving it both the high hardness of ceramic phases and the high toughness of metals.

[0071] Accordingly, the present invention also provides a method for preparing the above-mentioned tough molybdenum nitride-based protective coating, comprising the following steps: depositing a MoXN layer on the surface of a substrate.

[0072] In some alternative implementations, the substrate is cleaned before depositing the MoXN layer, for example, by ion etching.

[0073] Ion etching conditions may include: vacuum pressure not exceeding 5 × 10⁻⁶. -3 The argon gas pressure is 0.1Pa~0.3Pa (e.g., 0.1Pa, 0.15Pa, 0.2Pa, 0.25Pa or 0.3Pa), the furnace temperature is 150℃~350℃ (e.g., 150℃, 200℃, 250℃, 300℃ or 350℃), the ion source current is 0.1A~0.3A (e.g., 0.1A, 0.15A, 0.2A, 0.25A or 0.3A), the substrate bias voltage is -100V to -300V (e.g., -100V, -150V, -200V, -250V or -300V), and the time is 20min~40min (e.g., 20min, 25min, 30min, 35min or 40min).

[0074] In some alternative implementations, the MoXN layer can be prepared using a high-energy deposition method. This high-energy deposition method may include, for example, high-power magnetron sputtering or arc ion plating.

[0075] By employing a high-energy deposition method, the MoXN layer is bombarded with high-energy ions while simultaneously incorporating a high proportion of anionic N vacancies. This causes severe lattice distortion within the MoXN layer, introducing a large number of metallic bonds and high-density dislocations. This effectively solves the problem of achieving a balance between hardness and toughness in existing related coatings, thus preparing a protective coating that combines the ultra-high hardness of ceramic phases with the good toughness of metals.

[0076] In some typical implementations, MoXN layers can be prepared using high-power magnetron sputtering. High-power magnetron sputtering conditions may include: sputtering cathode power of 3.5kW~6.0kW, argon flow rate of 60sccm~100sccm, nitrogen flow rate of 30sccm~60sccm, gas pressure of 0.3Pa~1.2Pa, bias voltage of -80V to -150V, deposition temperature of 150℃~350℃, and deposition time of 60min~300min.

[0077] The sputtering cathode power can be 3.5kW, 4kW, 4.5kW, 5kW, 5.5kW or 6kW, or other values ​​within the range of 3.5kW to 6.0kW.

[0078] If the sputtering cathode power is too low, it will easily lead to a low sputtering deposition rate, which will damage the density of the coating; if the sputtering cathode power is too high, it will easily lead to instability in the sputtering process, resulting in more droplet defects and damaging the continuity of the coating.

[0079] The argon flow rate can be 60 sccm, 70 sccm, 80 sccm, 90 sccm or 100 sccm, or other values ​​within the range of 60 sccm to 100 sccm.

[0080] The nitrogen flow rate can be 30 sccm, 40 sccm, 50 sccm or 60 sccm, or other values ​​within the range of 30 sccm to 60 sccm.

[0081] If the nitrogen flow rate is too low, the coating may not be able to form a B1 face-centered cubic phase structure and may not provide enough covalent bonds; if the nitrogen flow rate is too high, the target surface may be poisoned, the sputtering rate may be reduced, and the film quality may be degraded.

[0082] The air pressure can be 0.3Pa, 0.5Pa, 1Pa or 1.2Pa, or other values ​​within the range of 0.3Pa to 1.2Pa.

[0083] The bias voltage can be -80V, -90V, -100V, -120V or -150V, or other values ​​within the range of -80V to -150V.

[0084] If the bias voltage is too low, it can easily lead to problems such as reduced adhesion between the coating and the substrate and poor density; if the bias voltage is too high, it can easily lead to excessive internal stress in the coating and embrittlement.

[0085] The deposition temperature can be 150℃, 200℃, 250℃, 300℃ or 350℃, or other values ​​within the range of 150℃ to 350℃.

[0086] The deposition time can be 60 min, 100 min, 150 min, 200 min, 250 min, or 300 min, or other values ​​within the range of 60 min to 300 min. Further, it can be 60 min to 200 min.

[0087] Furthermore, when the coating includes a MoQ transition layer, the MoQ transition layer is first deposited on the substrate surface, and then a MoXN layer is deposited on the surface of the MoQ transition layer.

[0088] In some optional embodiments, the MoQ transition layer is prepared by a low-energy deposition method or a high-energy deposition method. The high-energy deposition method may include, for example, high-power magnetron sputtering or arc ion plating; the low-energy deposition method may include, for example, DC magnetron sputtering.

[0089] In some typical implementations, the MoQ transition layer can be prepared by DC magnetron sputtering. DC magnetron sputtering conditions may include: sputtering cathode power of 3.0kW~5.0kW, argon flow rate of 80sccm~150sccm, gas pressure of 0.3Pa~1.2Pa, bias voltage of -80V to -150V, and deposition time of no more than 20min.

[0090] The sputtering cathode power can be 3kW, 3.5kW, 4kW, 4.5kW, or 5kW, or other values ​​within the range of 3.0kW to 5.0kW. Further, it can be 4.0kW to 5.0kW.

[0091] The argon flow rate can be 80 sccm, 90 sccm, 100 sccm, 120 sccm or 150 sccm, or other values ​​within the range of 80 sccm to 150 sccm.

[0092] The air pressure can be 0.3Pa, 0.5Pa, 0.8Pa, 1Pa or 1.2Pa, or other values ​​within the range of 0.3Pa to 1.2Pa.

[0093] The bias voltage can be -80V, -90V, -100V, -120V or -150V, or other values ​​within the range of -80V to -150V.

[0094] The deposition time can be 20 min, 15 min, 10 min, 5 min or 1 min, or other values ​​within the range not exceeding 20 min.

[0095] In some optional embodiments, the preparation of the above-mentioned tough molybdenum nitride-based protective coating may include:

[0096] First, place the workpiece or substrate inside a vacuum furnace and clean the substrate surface using argon ion etching.

[0097] Then, using high-purity metal Mo and Q elemental targets as cathodes and argon as working gas, a MoQ transition layer was deposited by DC magnetron sputtering.

[0098] Finally, using high-purity Mo and X elemental targets as cathodes and argon as working gas, a MoXN coating was deposited by high-power pulsed magnetron sputtering.

[0099] Furthermore, the present invention also provides an application of the above-mentioned tough molybdenum nitride-based protective coating, for example, the tough molybdenum nitride-based protective coating can be used in moving parts of equipment, cutting tools or molds.

[0100] In some alternative implementations, the moving parts of the equipment may include at least one of electronic equipment moving parts and aerospace equipment moving parts.

[0101] In some alternative implementations, the cutting tool includes a high-speed cutting tool.

[0102] In some alternative implementations, the mold includes cold-working and hot-working molds.

[0103] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0104] In this invention, the hardness results were obtained by nanoindentation testing using a TTX-NHT3 nanoindenter from Anton Paar, Switzerland. The instrument had a load accuracy of 0.02 μN, a depth resolution of 0.01 nm, a load frame stiffness of 107 N / m, and an initial thermal drift rate of <0.05 nm / s. During the test, a constant load mode was selected with a load of 10 mN to ensure that all indentation depths were no greater than 200 nm and always less than 1 / 10 of the coating thickness, in order to minimize the influence of the substrate.

[0105] Example 1

[0106] This embodiment provides a tough molybdenum nitride-based protective coating (without a MoQ transition layer), which uses M2 high-speed steel as a substrate to prepare the MoTiN layer. The preparation method includes:

[0107] Step 1: Place the degreased and dried substrate into the vacuum furnace chamber and evacuate until the furnace pressure does not exceed 5 × 10⁻⁶. - 3 Pa, heat the furnace to 200℃, hold the pressure and then introduce argon gas into the vacuum chamber until the furnace pressure reaches 0.1Pa. Turn on the ion source, set the current to 0.1A and the substrate bias voltage to -100V, and use argon ion etching to clean the substrate surface for 40 minutes.

[0108] Step 2: Using high-purity Mo and Ti elemental targets as cathodes, argon gas was introduced at 60 sccm and nitrogen gas at 30 sccm to maintain the furnace pressure at 0.3 Pa and the temperature at 240 °C. The power of the Mo target and the Ti target were set to 6.0 kW and 3.5 kW, respectively, and the substrate bias voltage was -80 V. High-power pulsed magnetron sputtering was used to deposit the MoTiN coating for 60 min.

[0109] The coating prepared in this embodiment was subjected to structural and performance testing, and the results are as follows: Figures 1-8 As shown in the figure. The relevant detection results indicate that the MoTiN layer prepared in this embodiment has a B1 face-centered cubic phase structure with no other phase detection signals; by atomic percentage, the MoTiN layer contains 75% Mo, 7% Ti, and 18% N, with 64% anion vacancies in the lattice; the MoTiN layer thickness is 2.2 μm, without a transition layer; the MoTiN layer exhibits a typical columnar crystal structure with an average grain size of 25 nm; the coating lattice shows severe distortion, with small-angle relative rotation between lattice spaces several nanometers apart; the dislocation density is 5.5 × 10⁻⁶. 11 cm -2 .

[0110] The tough molybdenum nitride-based protective coating prepared in this embodiment has a hardness of 45 GPa, and no surface cracks were found after being pressed in by a triangular pyramidal diamond indenter with a load of 200 mN.

[0111] Example 2

[0112] This embodiment provides a tough molybdenum nitride-based protective coating (including a MoQ transition layer and a MoXN layer), which is prepared using TC4 titanium alloy as the substrate. The preparation method includes:

[0113] Step 1: Place the degreased and dried substrate into the vacuum furnace chamber and evacuate until the furnace pressure does not exceed 5 × 10⁻⁶. - 3 Pa, heat the furnace to 350℃, hold the pressure and then introduce argon gas into the vacuum chamber until the furnace pressure reaches 0.3Pa. Turn on the ion source, set the current to 0.3A and the substrate bias voltage to -300V, and use argon ion etching to clean the substrate surface for 20 minutes.

[0114] Step 2: Using high-purity Mo and Ti elemental targets as cathodes, argon gas was introduced at 150 sccm to maintain the furnace pressure at 1.2 Pa. The power of the Mo target and Ti target was set to 5.0 kW and 4.5 kW, respectively, and the substrate bias voltage was -80 V. DC magnetron sputtering was used to deposit the MoTi transition layer for 20 min.

[0115] Step 3: Using high-purity Mo and Ti elemental targets as cathodes, argon gas was introduced at 100 sccm and nitrogen gas at 60 sccm. The furnace pressure was maintained at 1.2 Pa and the temperature at 150 °C. The power of the Mo target and the Ti target were set to 6.0 kW and 4.0 kW, respectively. The substrate bias voltage was -100 V. High-power pulsed magnetron sputtering was used to deposit the MoTiN layer for 300 min.

[0116] The coating prepared in this embodiment was subjected to structural and performance testing. The results showed that, by atomic percentage, the Mo, Ti, and N contents of the MoTiN layer were 70%, 10%, and 20%, respectively, and the crystal lattice contained 60% anion vacancies; the thickness of the MoTi transition layer was 0.5 μm, and the thickness of the MoTiN layer was 10 μm; the MoTiN layer exhibited a typical columnar crystal structure with an average grain size of 20 nm; and the dislocation density was 4.2 × 10⁻⁶. 11 cm -2 The tough molybdenum nitride-based protective coating has a hardness of 35 GPa and shows no surface cracks after being pressed in by a triangular pyramidal diamond indenter under a load of 200 mN.

[0117] Example 3

[0118] This embodiment provides a tough molybdenum nitride-based protective coating (including a MoQ transition layer and a MoXN layer), which is prepared using YG8 cemented carbide as the substrate. The preparation method includes:

[0119] Step 1: Place the degreased and dried substrate into the vacuum furnace chamber and evacuate until the furnace pressure does not exceed 5 × 10⁻⁶. - 3 Pa, heat the furnace to 150℃, hold the pressure and then introduce argon gas into the vacuum chamber until the furnace pressure reaches 0.2Pa. Turn on the ion source, set the current to 0.2A and the substrate bias voltage to -200V, and use argon ion etching to clean the substrate surface for 30 minutes.

[0120] Step 2: Using high-purity Mo and Ti elemental targets as cathodes, argon gas was introduced at 80 sccm to maintain the furnace pressure at 0.3 Pa. The power of the Mo target and Ti target was set to 5.0 kW and 4.0 kW, respectively, and the substrate bias voltage was -150 V. DC magnetron sputtering was used to deposit the MoTi transition layer for 16 min.

[0121] Step 3: Using high-purity Mo and Ti elemental targets as cathodes, argon gas was introduced at 90 sccm and nitrogen gas at 40 sccm to maintain the furnace pressure at 0.9 Pa and the temperature at 350 °C. The power of the Mo target and the Ti target were set to 5.5 kW and 3.8 kW, respectively, and the substrate bias voltage was -150 V. High-power pulsed magnetron sputtering was used to deposit the MoTiN layer for 200 min.

[0122] The coating prepared in this embodiment was subjected to structural and performance testing. The results showed that, by atomic percentage, the MoTiN layer contained 60% Mo, 15% Ti, and 25% N elements, with 50% anion vacancies in the crystal lattice; the MoTi transition layer thickness was 0.4 μm, and the MoTiN layer thickness was 6.0 μm; the MoTiN layer exhibited a typical columnar crystal structure with an average grain size of 40 nm; and the dislocation density was 7.5 × 10⁻⁶. 11 cm -2 The tough molybdenum nitride-based protective coating has a hardness of 43 GPa and shows no surface cracks after being pressed in by a triangular pyramidal diamond indenter with a load of 200 mN.

[0123] Example 4

[0124] This embodiment provides a tough molybdenum nitride-based protective coating (without a MoQ transition layer), which uses M2 high-speed steel as a substrate to prepare a MoZrN layer. The preparation method includes:

[0125] Step 1: Place the degreased and dried substrate into the vacuum furnace chamber and evacuate until the furnace pressure does not exceed 5 × 10⁻⁶. - 3 Pa, heat the furnace to 200℃, hold the pressure and then introduce argon gas into the vacuum chamber until the furnace pressure reaches 0.1Pa. Turn on the ion source, set the current to 0.1A and the substrate bias voltage to -100V, and use argon ion etching to clean the substrate surface for 40 minutes.

[0126] Step 2: Using high-purity Mo and Zr elemental targets as cathodes, argon gas was introduced at 60 sccm and nitrogen gas at 30 sccm to maintain the furnace pressure at 0.3 Pa and the temperature at 240 °C. The power of the Mo target and the Zr target were set to 6.0 kW and 3.5 kW, respectively, and the substrate bias voltage was -80 V. High-power pulsed magnetron sputtering was used to deposit the MoZrN coating for 60 min.

[0127] The structure and properties of the coating prepared in this embodiment were tested. The results showed that the MoZrN layer prepared in this embodiment has a B1 face-centered cubic phase structure; by atomic percentage, the MoTiN layer contains 73.2% Mo, 8.5% Zr, and 18.3% N, with 63.4% anion vacancies in the crystal lattice; the MoZrN layer has a thickness of 2.4 μm and no transition layer; the MoZrN layer exhibits a typical columnar crystal structure with an average grain size of 28 nm; and the dislocation density is 5.1 × 10⁻⁶. 11 cm -2 The coating has a hardness of 38 GPa, and no surface cracks were observed after indentation with a triangular pyramidal diamond indenter under a load of 200 mN.

[0128] Comparative Example 1

[0129] The difference between this comparative example and Example 1 is that the Mo target deposition power is 3.0 kW and the Ti target deposition power is 7.0 kW in step 2.

[0130] The structure and performance of the coating prepared in this comparative example were tested. The test results showed that the protective coating prepared in this comparative example exhibits a face-centered cubic + body-centered tetragonal two-phase structure (e.g., Figure 1 As shown in the figure, the MoTiN layer contains 22% Mo, 40% Ti, and 38% N by atomic percentage; the thickness of the MoTiN layer is 1.5 μm, the average grain size is 30 nm, and the dislocation density is 7 × 10⁻⁶. 10 cm -2 The protective coating has a hardness of only 25 GPa, and surface cracks appear after being pressed in by a triangular pyramidal diamond indenter with a load of 200 mN (e.g., Figure 8 (As shown).

[0131] Comparative Example 2

[0132] The difference between this comparative example and Example 1 is that the deposition bias voltage in step 2 is -200V.

[0133] The structure and properties of the coating prepared in this comparative example were tested. The results showed that the protective coating prepared in this comparative example exhibits a face-centered cubic + body-centered tetragonal two-phase structure. By atomic percentage, the MoTiN layer contained 75% Mo, 7% Ti, and 18% N. The thickness of the MoTiN layer was 1.5 μm, the average grain size was 30 nm, and the dislocation density was 7 × 10⁻⁶. 10 cm -2 The protective coating has a hardness of only 27 GPa, and cracks appear on its surface after being pressed in by a triangular pyramidal diamond indenter with a load of 200 mN.

[0134] Comparative Example 3

[0135] The difference between this comparative example and Example 1 is that the nitrogen flow rate in step 2 is 20 sccm.

[0136] The structure and properties of the coating prepared in this comparative example were tested. The results showed that the protective coating prepared in this comparative example exhibits a face-centered cubic + body-centered tetragonal dual-phase structure. By atomic percentage, the MoTiN layer contained 77% Mo, 11% Ti, and 12% N. The MoTiN coating had a thickness of 2.1 μm, an average grain size of 44 nm, and a dislocation density of 1.4 × 10⁻⁶. 11 cm -2The protective coating has a hardness of 25 GPa, and no surface cracks were observed after indentation with a triangular pyramidal diamond indenter under a load of 200 mN.

[0137] Comparative Example 4

[0138] The difference between this comparative example and Example 1 is that the deposition bias voltage in step 2 is -20V.

[0139] The structure and properties of the coating prepared in this comparative example were tested. The results showed that the coating prepared in this comparative example has a B1 face-centered cubic phase structure, with a Mo content of 74.2%, a Ti content of 7.4%, and a N content of 18.4%, and the crystal lattice contains 64% anion vacancies; the MoTiN layer thickness is 2.1 μm, the average grain size is 24 nm, and the dislocation density is 3.1 × 10⁻⁶. 11 cm -2 With a hardness of 29 GPa, the surface cracked after being pressed in by a triangular pyramidal diamond indenter under a load of 200 mN.

[0140] Comparative Example 5

[0141] The difference between this comparative example and Example 1 is that the nitrogen flow rate in step 2 is 70 sccm.

[0142] The structure and properties of the coating prepared in this comparative example were tested. The results showed that the coating prepared in this comparative example has a B1 face-centered cubic phase structure, with a Mo content of 73.2%, a Ti content of 6.8%, and a N content of 24%, and the crystal lattice contains 52% anion vacancies; the MoTiN layer thickness is 2.3 μm, the average grain size is 28 nm, and the dislocation density is 3.8 × 10⁻⁶. 11 cm -2 With a hardness of 34 GPa, the surface cracked after being pressed in by a triangular pyramidal diamond indenter under a load of 200 mN.

[0143] Comparative Example 6

[0144] The difference between this comparative example and Example 1 is that: in step 2, low-energy DC magnetron sputtering deposition is used, and the target power and other process parameters remain unchanged. The power of the Mo target and the Ti target are 6.0kW and 3.5kW, respectively.

[0145] The structure and properties of the coating prepared in this comparative example were tested. The results showed that the coating prepared in this comparative example has a B1 face-centered cubic phase structure, with a Mo content of 74.7%, a Ti content of 7.3%, and a N content of 20%, and the crystal lattice contains 60% anion vacancies; the MoTiN layer thickness is 2.7 μm, the average grain size is 38 nm, and the dislocation density is 1.8 × 10⁻⁶. 11 cm -2With a hardness of 24 GPa, the surface cracked after being pressed in by a triangular pyramidal diamond indenter under a load of 200 mN.

[0146] Comparative Example 7

[0147] The difference between this comparative example and Example 1 is that element X is Cr.

[0148] The structure and properties of the coating prepared in this comparative example were tested. The results showed that the coating contained both face-centered cubic (B1) and hexagonal phases, with a Mo content of 66%, a Cr content of 16%, and a N content of 18%. The anion vacancies in the cubic phase lattice were <60%. The MoCrN layer thickness was 3.4 μm, the average grain size was 36 nm, and the dislocation density was 2.6 × 10⁻⁶. 11 cm -2 With a hardness of 27 GPa, the surface cracked after being pressed in by a triangular pyramidal diamond indenter under a load of 200 mN.

[0149] In summary, the tough molybdenum nitride-based protective coating provided by this invention combines the advantages of high hardness and high toughness. It features a covalent-metal hybrid bonding mechanism and an ultrafine nanocrystalline structure. Furthermore, the nanocrystalline lattice contains numerous N vacancies, causing large lattice distortion and inducing a large number of dislocations within the lattice. This results in the MoXN coating prepared by this invention exhibiting a synergistic hardening effect of fine grains, lattice distortion, and dislocations. The dislocations also provide plastic deformation capability, increasing the coating's toughness. Moreover, the preparation method of the tough molybdenum nitride-based protective coating provided by this invention is simple, efficient, environmentally friendly, and uses low-cost materials, showing promising application prospects in the field of wear-resistant protection.

[0150] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A tough molybdenum nitride-based protective coating, characterized in that, The tough molybdenum nitride-based protective coating includes a MoXN layer; The MoXN layer comprises 60% to 75% Mo and 7% to 15% X, with the balance being N, based on atomic percentage; wherein X includes at least one element selected from Ti, Zr, V and Nb. The MoXN layer has a B1 face-centered cubic phase structure and a nanocrystalline structure, which contains lattice distortion and high-density dislocations. The dislocation density in the MoXN layer is not less than 4.2 × 10⁻⁶. 11 cm -2 .

2. The tough molybdenum nitride-based protective coating according to claim 1, characterized in that, The tough molybdenum nitride-based protective coating further includes a MoQ transition layer, wherein the MoXN layer is disposed on the surface of the MoQ transition layer; wherein Q includes at least one element selected from Ti, Zr, V and Nb.

3. The tough molybdenum nitride-based protective coating according to claim 1 or 2, characterized in that, The MoXN layer also has at least one of the following characteristics: Feature 1: The nanocrystalline structure is a nanocolumnar crystal structure; Feature 2: The thickness of the MoXN layer does not exceed 10 μm; Feature 3: The hardness of the tough molybdenum nitride-based protective coating is not less than 35 GPa; Feature 4: The tough molybdenum nitride-based protective coating shows no surface cracks after being pressed in with a triangular pyramid indenter and subjected to a load of 200mN.

4. A method for preparing a tough molybdenum nitride-based protective coating as described in any one of claims 1 to 3, characterized in that, Includes the following steps: The MoXN layer is deposited on the substrate surface.

5. The preparation method according to claim 4, characterized in that, Before depositing the MoXN layer, the substrate is first cleaned; Cleaning is performed using ion etching. Ion etching conditions include: vacuum pressure not exceeding 5 × 10⁻⁶. -3 The argon gas pressure is 0.1 Pa to 0.3 Pa, the furnace temperature is 150℃ to 350℃, the ion source current is 0.1 A to 0.3 A, the substrate bias voltage is -100 V to -300 V, and the time is 20 min to 40 min.

6. The preparation method according to claim 4, characterized in that, The MoXN layer was prepared using a high-energy deposition method. The high-energy deposition method includes high-power magnetron sputtering or arc ion plating.

7. The preparation method according to claim 6, characterized in that, The MoXN layer was prepared by high-power magnetron sputtering. The high-power magnetron sputtering conditions include: argon flow rate of 60 sccm to 100 sccm, nitrogen flow rate of 30 sccm to 60 sccm, gas pressure of 0.3 Pa to 1.2 Pa, bias voltage of -80 V to -150 V, deposition temperature of 150 °C to 350 °C, and deposition time of 60 min to 300 min; the sputtering targets are metallic Mo and elemental X targets; the power of the Mo target is 5.5 kW to 6.0 kW, and the power of the elemental X target is 3.5 kW to 4.0 kW.

8. The preparation method according to any one of claims 4 to 7, characterized in that, When the coating includes a MoQ transition layer, the MoQ transition layer is first deposited on the substrate surface, and then the MoXN layer is deposited on the surface of the MoQ transition layer; The MoQ transition layer is prepared by a low-energy deposition method or a high-energy deposition method; The high-energy deposition method includes high-power magnetron sputtering or arc ion plating; the low-energy deposition method includes DC magnetron sputtering.

9. The preparation method according to claim 8, characterized in that, The MoQ transition layer was prepared by DC magnetron sputtering. The DC magnetron sputtering conditions include: sputtering cathode power of 3.0kW~5.0kW, argon flow rate of 80sccm~150sccm, gas pressure of 0.3Pa~1.2Pa, bias voltage of -80V to -150V, and deposition time not exceeding 20min; sputtering targets are metallic Mo and Q elemental targets; Mo target power is 5.0kW, and Q elemental target power is 4.0kW~4.5kW.

10. The application of a tough molybdenum nitride-based protective coating as described in any one of claims 1 to 3, characterized in that, The tough molybdenum nitride-based protective coating is used in moving parts of equipment, cutting tools, or molds.

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