A spatial multilayer lubricating film and preparation method thereof

Abstract

The present invention provides a spatial multilayer lubricating film and a preparation method thereof, relating to the field of surface engineering. The spatial multilayer lubricating film comprises a nitriding layer formed on the surface of a metal substrate, the surface of the nitriding layer being formed with a microtexture, a Cr bonding layer and a composite solid lubricating film being sequentially arranged on the microtexture, the composite solid lubricating film comprising a Cr / MoS2 gradient intermediate layer and a Cr / MoS2 solid lubricating layer sequentially arranged on the surface of the Cr bonding layer. The nitriding layer can improve the bearing capacity and toughness of the metal substrate, and the microtexture can not only reduce friction and wear, but also store molybdenum disulfide grinding. The multilayer structure plays a synergistic role, enabling the gradient nano-multilayer lubricating film to fully exert its performance, reduce the friction coefficient and wear rate, improve the bearing capacity and toughness of the substrate, and extend the life of the substrate. This technology can be applied to movable parts such as heavy-duty and long-life gears, shafts, and guide rods in space.

Description

Technical Field

[0001] The present invention relates to the field of surface engineering, and in particular to a spatial multilayer lubricating film and a preparation method thereof. Background Art

[0002] Gear transmission pairs, shafts, guide rods, and other active components are the primary supporting components of various transmission and drive mechanisms in space. As the performance requirements for space gears continue to increase, the alternating and impact loads they bear are increasing, and the stresses they experience are becoming more complex, posing greater challenges to the strength, lifespan, and reliability of gear materials. Surface treatment is an ideal choice when high speeds, high loads, and long life are often required of gears, while maintaining strict weight and size constraints.

[0003] While ion nitriding can improve gear surface hardness and enhance core toughness, under heavy-load conditions, relying solely on nitriding can no longer meet the requirements for fatigue strength, low friction and wear, and high load-bearing capacity. This is because the nitrided layer is prone to premature failure under multiple stresses. While a single MoS2 solid lubricant film offers excellent spatial lubrication properties, it is not suitable for use in friction pairs with high contact stresses. Surface texturing, which alters the contact state of friction pairs, is an effective method for increasing load capacity and reducing wear. However, under certain heavy-load and complex operating conditions, one or a combination of the three methods mentioned above is no longer sufficient.

[0004] Patent application number CN201711395150.7 reports a method for preparing a vacuum plasma self-lubricating coating on a laser micro-textured surface. This method combines laser etching micro-texturing and vacuum plasma spraying of a self-lubricating coating. The depth of the processed sinusoidal micro-texture is 50 to 70 μm, and the thickness of the bonding layer and the self-lubricating coating is 70 to 120 μm. However, considering the requirements for assembly accuracy and life of space movable parts, this method is difficult to adapt to precision movable parts in space.

[0005] Patent application number CN200810189022.1 reports a method for preparing a textured diamond-like carbon composite film for water lubrication. However, considering that space is a vacuum environment, this method is not suitable for space lubrication.

[0006] Patents with application numbers CN201010196546.0 and CN201710695375.8 respectively report a method for preparing a molybdenum disulfide-based lubricating and wear-resistant composite film and a method for preparing a molybdenum disulfide-based composite lubricating film for satellite use. The films prepared by these two methods have obvious advantages under light-load conditions in space, but under heavy-load conditions, the film life is relatively short.

[0007] How to achieve high spatial load and long-life lubrication under some heavy-load and complex working conditions is a technical problem that needs to be solved urgently by technical personnel in this field. Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present invention is to overcome the defect that the spatial lubrication technology in the prior art is difficult to meet heavy-load and complex working conditions, thereby providing a spatial multilayer lubricating film and a preparation method thereof.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] In the first aspect, the present invention provides a spatial multilayer lubricating film, including a nitriding layer formed on the surface of a metal substrate, wherein a microtexture is formed on the surface of the nitriding layer, and a Cr bonding layer and a composite solid lubricating film are sequentially arranged on the microtexture, and the composite solid lubricating film includes a Cr / MoS2 gradient intermediate layer and a Cr / MoS2 solid lubricating layer sequentially arranged on the surface of the Cr bonding layer.

[0011] Furthermore, the metal substrate is a CF170 substrate.

[0012] Furthermore, the nitriding layer formed on the surface of the metal substrate has a depth of 70 to 90 μm and a hardness of HV 0.05 It is 780.

[0013] Furthermore, the micro texture is a circular pit array, the diameter of the circular pit is 25 to 50 μm, the distance between adjacent pits is 100 to 300 μm, and the pit depth is 6 to 10 μm.

[0014] Furthermore, the thickness of the Cr bonding layer is 100-200 nm; the thickness of the Ct / MoS2 gradient intermediate layer is 100-200 nm; and the thickness of the Cr / MoS2 solid lubrication layer is 800-1200 nm.

[0015] Furthermore, in the Cr / MoS2 gradient intermediate layer, in the direction away from the Cr bonding layer, the Cr content gradually decreases from 100at% to 8-12at%, and the MoS2 content gradually increases from 0at% to 88-92at%; in the Cr / MoS2 solid lubrication layer, the Cr content is 8-12at%, and the MoS2 content is 88-92at%.

[0016] In a second aspect, the present invention provides a method for preparing the spatial multilayer lubricating film, comprising the following steps:

[0017] (1) Plasma nitriding treatment is performed on the surface of the metal substrate to form a nitrided layer;

[0018] (2) etching a microtexture on the surface of the nitrided gold layer;

[0019] (3) preparing a Cr bonding layer on the micro-textured surface;

[0020] (4) preparing a composite solid lubricating film on the surface of the Cr bonding layer, that is, preparing a Cr / MoS2 gradient intermediate layer and a Cr / MoS2 solid lubricating layer in sequence.

[0021] Furthermore, in step (1), the nitriding temperature is 460-500° C., the NH 3 gas pressure is 220-280 Pa, and the nitriding time is 8-12 h.

[0022] Furthermore, in step (2), a femtosecond pulsed Nd:YAG laser is used, with a laser wavelength of 1028 nm, a beam spot diameter of 10 to 30 μm, a scanning speed of 500 to 800 mm / s, and a pulse width of 300 to 500 fs.

[0023] Furthermore, in step (3), the argon pressure is 0.3 to 0.6 Pa, a DC bias of -50 V to -100 V is applied to the substrate, and the Cr bonding layer is prepared by magnetron sputtering, the Cr target power is 4.0 to 6.0 kW, and the deposition time is 5 to 8 min.

[0024] Furthermore, in step (4), the argon gas pressure is 0.5 to 1.0 Pa, a DC bias of -50 to -100 V is applied to the substrate, and the Cr / MoS2 gradient intermediate layer and the Cr / MoS2 solid lubricating layer are prepared by a multi-target magnetron sputtering method. When preparing the Cr / MoS2 gradient intermediate layer, the Cr target power is gradually reduced from 4.0 to 6.0 kW to 0.6 to 1.0 kW, and the MoS2 target power is gradually increased from 0 kW to 1.5 to 2.0 kW within 8 to 12 minutes; then, the Cr / MoS2 solid lubricating layer is prepared with the final power of the Cr target and the MoS2 target when preparing the Cr / MoS2 gradient intermediate layer, and the deposition time is 60 to 90 minutes.

[0025] Furthermore, the purity of the Cr target is 99.99%; the purity of the MoS2 target is 99.99%.

[0026] The technical solution of the present invention has the following advantages:

[0027] The present invention combines the nitriding layer, micro texture and gradient nano multilayer lubricating film (Cr bonding layer, Cr / M oThe combination of a S2 gradient intermediate layer and a Cr / MoS2 solid lubricant layer improves the bearing capacity and toughness of the metal substrate. The microtexture not only reduces friction and wear but also stores molybdenum disulfide for grinding. The multi-layer structure works synergistically, fully unleashing the full potential of the gradient nano-multilayer lubricant film, reducing the friction coefficient and wear rate, improving the bearing capacity and toughness of the substrate, and extending its life. This technology can be applied to movable components such as heavy-duty, long-life gears, shafts, and guide rods in space applications.

[0028] The method for preparing a multilayer lubricating film for space provided by the present invention combines three surface modification methods: first, ion nitriding is performed on the metal substrate, then microtexturing is performed on the nitrided layer by femtosecond laser etching, and finally, magnetron sputtering technology is used to prepare a Cr bonding layer, a Cr / MoS2 gradient intermediate layer, and a Cr / MoS2 solid lubricating layer on the microtextured surface. The organic combination of the three surface engineering technologies can make up for their respective limitations and give full play to their respective advantages, not only reducing the amount of wear and extending the life of the solid lubricating film, but also improving the bearing capacity and toughness of the substrate. Although the present invention involves three surface modification methods, namely nitriding, microtexturing, and physical vapor deposition, it is easy to implement, the method is simple and easy to control, and has application prospects in high-load-bearing and long-life movable parts in space. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 is a process flow chart for preparing a spatial multilayer lubricating film in Examples 1 and 2 of the present invention;

[0031] Figure 2 is the micro-texture design diagram in Example 1 of the present invention;

[0032] Figure 3 is a curve showing the variation of the friction coefficient of the spatial multilayer lubricating film prepared in Example 1 of the present invention with the sliding distance;

[0033] Figure 4 is the micro-texture design diagram in Example 2 of the present invention;

[0034] Figure 5 3 is a curve showing the change of the friction coefficient of the spatial multilayer lubricating film prepared in Example 2 of the present invention as a function of the sliding distance.

[0035] Reference numerals:

[0036] 1-metal matrix; 2-nitriding layer; 3-microtexture; 4-Cr bonding layer; 5-composite solid lubricating film. DETAILED DESCRIPTION

[0037] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection of the present invention.

[0038] If specific experimental steps or conditions are not specified in the examples, the procedures or conditions of conventional experimental steps described in the literature in the field can be followed. All raw materials and instruments used are commercially available, including but not limited to those used in the examples of this application.

[0039] Example 1

[0040] This embodiment provides a spatial multilayer lubricating film, the preparation process is as follows Figure 1 As shown, the specific preparation steps are as follows:

[0041] Step (1): The metal substrate 1 (CF170) is nitrided in a plasma nitriding furnace. Ammonia gas is introduced into the plasma nitriding furnace at a pressure of 220 Pa, a nitriding temperature of 460°C, a nitriding time of 8 hours, and an ammonia purity of 99.9%. After the nitriding is completed, the equipment is turned off and the furnace is cooled to room temperature. A nitriding layer 2 is formed on the surface of the metal substrate 1. The depth of the nitriding layer 2 is 70 μm and the hardness is HV 0.05 is 780;

[0042] Step (2): A femtosecond pulsed Nd:YAG laser is used to etch a micro texture 3 on the surface of the nitrided layer 2. The laser wavelength is 1028 nm, the beam spot diameter is 10 μm, the scanning speed is 500 mm / s, and the pulse width is 300 fs. The micro texture design is as follows: Figure 2 The figure shows a prototype pit array. The diameter of the circular pit microtexture is 25 μm, the spacing between adjacent pits is 100 μm, and the pit depth is 6 μm:

[0043] Step (3): Argon gas was introduced into the coating vacuum chamber at a pressure of 0.3 Pa, a pulse bias of -800 V was applied to the substrate, and the surface of the micro-textured metal substrate was cleaned for 10 minutes; the argon gas pressure was adjusted to 0.3 Pa, a DC bias of -50 V was applied to the substrate, and a Cr bonding layer 4 was prepared by magnetron sputtering. The Cr target power was 4.0 kW, the purity of the Cr target was 99.99%, the deposition time was 5 minutes, and the thickness of the Cr bonding layer 4 was 100 nm;

[0044] Step (4): The argon pressure was adjusted to 0.3 Pa, a DC bias of -50 V was applied to the substrate, and a composite solid lubricating film 5 was prepared by a multi-target magnetron sputtering method (a Cr / MoS2 gradient intermediate layer and a Cr / MoS2 solid lubricating layer were prepared in sequence). The purity of the Cr target was 99.99%; the purity of the MoS2 target was 99.99%. When preparing the Cr / MoS2 gradient intermediate layer, the Cr target power was gradually reduced from 4.0 kW to 0.6 kW within 8 minutes, and the MoS2 target power was gradually increased from 0 kW to 2.0 kW. The thickness of the Cr / MoS2 gradient intermediate layer was 1 00nm, the Cr content gradually decreases from 100at% to 8at%, and the MoS2 content gradually increases from 0at% to 92at% synchronously; then, the Cr / MoS2 solid lubricating layer is stably prepared at the final power of the Cr target and the MoS2 target when preparing the Cr / MoS2 gradient intermediate layer, the deposition time is 60min, the thickness of the Cr / MoS2 solid lubricating layer is 800nm, the Cr content is 8at%, and the MoS2 content is 92at%; after the film layer reaches the actual required thickness, the coating is stopped, and the temperature in the coating room is reduced to below 60℃ to obtain the spatial multilayer lubricating film.

[0045] The tribological properties of the film were tested using a vacuum ball-disc friction tester (Anton Paar), and the vacuum degree was better than 5×10 -3 pa, the grinding part is a 9Cr18 steel ball with a diameter of φ8mm, the load is 5N, and the rotation speed is 1000r / min.

[0046] The curve of friction coefficient changing with sliding distance is as follows: Figure 3 It can be seen that the spatial multilayer lubricating film prepared in this embodiment has a low friction coefficient, which meets the requirements of high load-bearing and long-life lubrication in space.

[0047] Example 2

[0048] This embodiment provides a spatial multilayer lubricating film, the preparation process is as follows Figure 1 As shown, the specific preparation steps are as follows:

[0049] Step (1): The metal substrate 1 (CF170) is nitrided in a plasma nitriding furnace. Ammonia gas is introduced into the plasma nitriding furnace at a pressure of 280 Pa, a nitriding temperature of 500 ° C, a nitriding time of 12 hours, and an ammonia purity of 99.9%. After the nitriding is completed, the equipment is turned off and the furnace is cooled to room temperature. A nitriding layer 2 is formed on the surface of the metal substrate 1. The depth of the nitriding layer 2 is 90 μm and the hardness is HV 0.05 is 780;

[0050] Step (2): Use femtosecond pulsed Nd:YAG laser to etch micro texture 3 on the surface of nitrided layer 2, with laser wavelength of 1028nm, beam spot diameter of 30μm, scanning speed of 800mm / s, and pulse width of 500fs: Micro texture design is as follows Figure 4 The figure shows a prototype pit array, where the diameter of the circular pit microtexture is 50 μm, the spacing between adjacent pits is 300 μm, and the pit depth is 10 μm.

[0051] Step (3): Argon gas was introduced into the coating vacuum chamber at a pressure of 0.6 Pa, a pulse bias of -1000 V was applied to the substrate, and the surface of the micro-textured metal substrate was cleaned for 15 minutes; the argon gas pressure was adjusted to 0.6 Pa, a DC bias of -100 V was applied to the substrate, and a Cr bonding layer 4 was prepared by magnetron sputtering. The Cr target power was 6.0 kW, the purity of the Cr target was 99.99%, the deposition time was 8 minutes, and the thickness of the Cr bonding layer 4 was 200 nm;

[0052] Step (4): The argon pressure was adjusted to 0.6 Pa, a DC bias of -100 V was applied to the substrate, and a composite solid lubricating film 5 was prepared by a multi-target magnetron sputtering method (a Cr / MoS2 gradient intermediate layer and a Cr / MoS2 solid lubricating layer were prepared in sequence). The purity of the Cr target was 99.99%; the purity of the MoS2 target was 99.99%. When preparing the Cr / MoS2 gradient intermediate layer, the Cr target power was gradually reduced from 6.0 kW to 1.0 kW within 12 minutes, and the MoS2 target power was gradually increased from 0 kW to 1.5 kW. The thickness of the Cr / MoS2 gradient intermediate layer was 20 0nm, the Cr content gradually decreases from 100at% to 12at%, and the MoS2 content gradually increases from 0at% to 88at% synchronously; then, the Cr / MoS2 solid lubricating layer is stably prepared at the final power of the Cr target and the MoS2 target when preparing the Cr / MoS2 gradient intermediate layer, the deposition time is 90min, the thickness of the Cr / MoS2 solid lubricating layer is 1000nm, the Cr content is 12at%, and the MoS2 content is 88at%; after the film layer reaches the actual required thickness, the coating is stopped, and the temperature in the coating room is reduced to below 60℃ to obtain the spatial multilayer lubricating film.

[0053] The tribological properties of the film were tested using a vacuum ball-disc friction tester (Anton Paar), and the vacuum degree was better than 5×10 -3 Pa, the grinding part is a 9Cr18 steel ball with a diameter of Φ8mm, the load is 5N, and the rotation speed is 1000r / min.

[0054] The curve of friction coefficient changing with sliding distance is as follows: Figure 5 It can be seen that the spatial multilayer lubricating film prepared in this embodiment has a low friction coefficient, which meets the requirements of high load-bearing and long-life lubrication in space.

[0055] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A spatial multilayer lubricating film, characterized in that: It includes a nitriding layer formed on the surface of a metal substrate, the surface of the nitriding layer is formed with a microtexture, a Cr bonding layer and a composite solid lubricating film are sequentially arranged on the microtexture, and the composite solid lubricating film includes a Cr / MoS2 gradient intermediate layer and a Cr / MoS2 solid lubricating layer sequentially arranged on the surface of the Cr bonding layer.

2. The spatial multilayer lubricating film according to claim 1, characterized in that The metal matrix is ​​a CF170 matrix; The depth of the nitriding layer formed on the metal substrate is 70 to 90 μm, and the hardness is HV 0.05 It is 780.

3. The spatial multilayer lubricating film according to claim 1, characterized in that The micro texture is a circular pit array, the diameter of the circular pit is 25 to 50 μm, the distance between adjacent pits is 100 to 300 μm, and the pit depth is 6 to 10 μm.

4. The spatial multilayer lubricating film according to claim 1, characterized in that The thickness of the Cr bonding layer is 100-200 nm; the thickness of the Cr / MoS2 gradient intermediate layer is 100-200 nm; the thickness of the Cr / MoS2 solid lubricating layer is 800-1200 nm; In the Cr / MoS2 gradient intermediate layer, in the direction away from the Cr bonding layer, the Cr content gradually decreases from 100at% to 8-12at%, and the MoS2 content gradually increases from 0at% to 88-92at%; In the Cr / MoS2 solid lubricating layer, the Cr content is 8-12 at%, and the MoS2 content is 88-92 at%.

5. The method for preparing a spatial multilayer lubricating film according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Plasma nitriding treatment is performed on the surface of the metal substrate to form a nitrided layer; (2) etching a micro texture on the surface of the nitrided layer; (3) preparing a Cr bonding layer on the micro-textured surface; (4) preparing a composite solid lubricating film on the surface of the Cr bonding layer, that is, preparing a Cr / MoS2 gradient intermediate layer and a Cr / MoS2 solid lubricating layer in sequence.

6. The method for preparing a spatial multilayer lubricating film according to claim 5, characterized in that: In step (1), the nitriding temperature is 460-500° C., the NH 3 gas pressure is 220-280 Pa, and the nitriding time is 8-12 h.

7. The method for preparing a spatial multilayer lubricating film according to claim 5, characterized in that: In step (2), a femtosecond pulsed Nd:YAG laser is used, with a laser wavelength of 1028 nm, a beam spot diameter of 10 to 30 μm, a scanning speed of 500 to 800 mm / s, and a pulse width of 300 to 500 fs.

8. The method for preparing a spatial multilayer lubricating film according to claim 5, characterized in that: In step (3), the argon gas pressure is 0.3 to 0.6 Pa, a DC bias of -50 V to -100 V is applied to the substrate, and the Cr bonding layer is prepared by magnetron sputtering, the Cr target power is 4.0 to 6.0 kW, and the deposition time is 5 to 8 minutes.

9. The method for preparing a spatial multilayer lubricating film according to claim 5, characterized in that: In step (4), the argon gas pressure is 0.5 to 1.0 Pa, a DC bias of -50 to -100 V is applied to the substrate, and the Cr / MoS2 gradient intermediate layer and the Cr / MoS2 solid lubricating layer are prepared by a multi-target magnetron sputtering method. When preparing the Cr / MoS2 gradient intermediate layer, the Cr target power is gradually reduced from 4.0 to 6.0 kW to 0.6 to 1.0 kW, and the MoS2 target power is gradually increased from 0 kW to 1.5 to 2.0 kW within 8 to 12 minutes; then, the Cr / MoS2 solid lubricating layer is prepared using the final power of the Cr target and the MoS2 target when preparing the Cr / MoS2 gradient intermediate layer, and the deposition time is 60 to 90 minutes.

10. The method for preparing a spatial multilayer lubricating film according to claim 5, characterized in that: The purity of the Cr target is 99.99%; The purity of the MoS2 target is 99.99%.

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