Low-friction solid / grease lubricating system as well as preparation method, use method and application thereof

Abstract

The invention relates to a low-friction solid / grease lubricating system as well as a preparation method, a use method and application thereof. The solid / grease lubricating system is composed of a high-entropy nitride coating and lubricating grease, and the high-entropy nitride coating is deposited on a bearing steel substrate and comprises a Cr transition layer and a CrAlVTiNbN high-entropy nitride coating. The high-entropy nitride coating is prepared by adopting a high-power pulse magnetron sputtering technology, and the process is simple and controllable. The solid / grease lubrication system can realize ultralow friction (friction coefficient lt: 0.1) in an atmospheric environment of 350 DEG C, and provides effective surface protection for moving parts of an aero-engine.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of moving parts surface protection, particularly to a low-friction solid / grease lubrication system, its preparation, use method and application. BACKGROUND

[0002] During the operation of an aero-engine, the performance of the lubrication system directly affects the efficiency and reliability of the engine. Traditional lubricating oil and grease often cannot effectively maintain their lubrication performance under high temperature conditions, leading to increased friction coefficient and accelerated wear, thereby affecting the overall performance of the engine. Therefore, it is particularly important to develop an ultra-low friction lubrication system suitable for high temperature conditions.

[0003] The present application relates to a low-friction solid / grease lubrication system, its preparation, use method and application. The lubrication system can achieve ultra-low friction at a working temperature as high as 350℃, effectively reducing the friction coefficient and significantly reducing wear. This innovation not only improves the operating efficiency of the aero-engine, but also prolongs its service life, providing a new solution for high-performance lubricating materials in the aviation field. By optimizing the composition and structure of the lubrication system, the present application opens up a new direction for the development of high-temperature lubrication technology. SUMMARY

[0004] The main purpose of the present application is to provide a low-friction solid / grease lubrication system, its preparation, use method and application, which solves the technical problem of high friction coefficient and low maximum temperature tolerance of the solid / grease lubrication system in the prior art at room temperature.

[0005] The solid / grease lubrication system is composed of a high-entropy nitride coating and a lubricating grease. The high-entropy nitride coating includes a Cr transition layer and a CrAlVTiNbN high-entropy nitride coating. The atomic proportions of the elements in the CrAlVTiNbN high-entropy nitride coating are 0.2Cr-0.09Al-0.07V-0.05Ti-0.04Nb-0.55N. The CrAlVTiNbN high-entropy nitride coating is prepared by high-power pulsed magnetron sputtering technology. The lubricating grease is a four-urea lubricating grease.

[0006] Another purpose of the present application is to provide a preparation method of a high-entropy nitride coating, comprising the following steps: (1) Pretreatment The substrate is ultrasonically cleaned for 30 min, dried and then placed in a dry chamber for standby; (2) Pre-sputtering cleaning The substrate treated in step (1) is placed in a vacuum chamber, vacuumized, heated, and set at a temperature of 350 DEG C and a vacuum degree of less than 0.001 Pa, and then ion etching is performed on the surface of the substrate, Ar is introduced at a flow rate of 350 sccm, and the etching gas pressure is 1.1 Pa, a pulsed bias voltage is applied to the substrate at a bias voltage of -800 V, a frequency of 40 kHz, and a pulse width of 4 mu s, and the substrate is pre-sputtered and cleaned with Ar plasma for 20-30 min. (3) Depositing a Cr transition layer A high-power pulsed magnetron sputtering technique is used, the Ar flow rate is adjusted to 60 sccm, the pulsed bias voltage is adjusted to -200 V, a high-power pulsed power source is applied to a pure Cr target, the peak current is adjusted to 240 A, the frequency is 100 Hz, the pulse width is 300 mu s, a Cr transition layer is deposited, and the deposition time is 10 min. (4) Depositing a CrAlVTiNbN high-entropy nitride coating A high-power pulsed magnetron sputtering technique is used, the peak current of the CrAlVTiNb alloy target is 240 A, the frequency is 100 Hz, the pulse width is 300 mu s, the Ar flow rate is kept unchanged, N2 is introduced at a flow rate of 20 sccm, a pulsed bias voltage is applied to the substrate at a bias voltage of -120 V, a frequency of 40 kHz, and a pulse width of 12 mu s, the deposition time is 180 min, a CrAlVTiNbN coating is deposited, and the thickness of the CrAlVTiNbN coating is 0.7-1.5 mu m.

[0007] The solid / grease lubrication system is applied to the surface protection field of moving parts of an aero-engine, and in an atmospheric environment at 350 DEG C, the friction coefficient is 0.006, the solid / grease lubrication system can achieve an ultra-low friction effect and exhibits excellent tribological properties.

[0008] The method for using the low-friction solid / grease lubrication system, which is used to uniformly and continuously apply four-urea grease to the surface of the CrAlVTiNbN high-entropy nitride coating.

[0009] The application of the low-friction solid / grease lubrication system, which is used for aero special materials, such as an aero-engine.

[0010] The present application has the advantages of high power pulse magnetron sputtering technology, which has high metal ionization rate and high plasma density, ensures the excellent surface quality and uniform composition and structure of the coating deposition. By adjusting the coating process parameters, the coating can be obtained under the best deposition conditions, which provides an effective technical means for constructing solid / lipid lubrication system to achieve ultra-low friction. The coating itself can withstand a temperature of 500℃, most lubricating oils and greases can withstand a temperature of about 220℃, and the coating combined with the lubricating grease can withstand a high temperature of 350℃, thereby improving the temperature of the solid / lipid lubrication system. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is the friction coefficient curve of the coating prepared in Example 1 and the lubricating grease at 350℃; Figure 2 is the friction coefficient curve of the coating prepared in Example 1 and the lubricating oil at 350℃; Figure 3 is the friction coefficient curve of the 9Cr18 steel substrate and the lubricating grease at 350℃. DETAILED DESCRIPTION

[0012] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0013] The solid / lipid lubrication system is composed of a high-entropy nitride coating and a lubricating grease, the high-entropy nitride coating comprises a Cr transition layer and a CrAlVTiNbN high-entropy nitride coating, the elements in the CrAlVTiNbN high-entropy nitride coating are in atomic proportions of 0.2Cr-0.09Al-0.07V-0.05Ti-0.04Nb-0.55N, the CrAlVTiNbN high-entropy nitride coating is prepared by high power pulse magnetron sputtering technology, and the lubricating grease is a four-urea lubricating grease.

[0014] Further, the preparation method of the high-entropy nitride coating comprises the following steps: (1) Pretreatment The substrate is ultrasonically cleaned for 30 min, dried and then placed in a dry cavity for standby; the substrate cleaning method can be a commonly used cleaning method in the art, and the substrate can be bearing steel or other conventional choices.

[0015] (2) Pre-sputtering cleaning The substrate treated in step (1) is placed in a vacuum chamber, vacuumized, and heated to 350℃ under a vacuum of less than 0.001 Pa, and ion etching is performed on the surface of the substrate, Ar is introduced at a flow rate of 350 sccm, the etching gas pressure is 1.1 Pa, pulsed bias voltage is applied to the substrate at a bias voltage of -800 V, a frequency of 40 kHz, and a pulse width of 4 μs, and the substrate is pre-sputtered and cleaned with Ar plasma for 20-30 min; (3) Depositing a Cr transition layer A Cr transition layer is deposited using high-power pulsed magnetron sputtering technology, adjusting the Ar flow rate to 60 sccm, adjusting the pulsed bias voltage to -200 V, applying a high-power pulsed power source to a pure Cr target, adjusting the peak current to 240 A, the frequency to 100 Hz, and the pulse width to 300 μs, and the deposition time is 10 min. (4) Depositing a CrAlVTiNbN high-entropy nitride coating A CrAlVTiNbN coating is deposited using high-power pulsed magnetron sputtering technology, the peak current of the CrAlVTiNb alloy target is 240 A, the frequency is 100 Hz, the pulse width is 300 μs, the Ar flow rate is kept constant, N2 is introduced at a flow rate of 20 sccm, pulsed bias voltage is applied to the substrate at a bias voltage of -120 V, a frequency of 40 kHz, and a pulse width of 12 μs, and the deposition time is 180 min, and the CrAlVTiNbN coating has a thickness of 0.7-1.5 μm.

[0016] The solid / grease lubrication system is applied to the field of surface protection of moving parts of an aero-engine, and in an atmosphere at 350℃, the friction coefficient is 0.006, the solid / grease lubrication system can achieve ultra-low friction effect and exhibit excellent tribological performance.

[0017] The method for using the low-friction solid / grease lubrication system is to uniformly and continuously apply four-urea grease to the surface of the CrAlVTiNbN high-entropy nitride coating. The core of the operation is to ensure that the contact area between the coating and the friction pair is completely covered with the grease, so as to avoid local dry friction due to the lack of grease and affect the friction and wear performance and service life of the coating. The amount of grease used can be adjusted according to the size of the contact area to form a uniform and continuous lubricating film. Embodiment

[0018] An ultra-low friction solid / grease lubrication system for an aero-engine, which is composed of a high-entropy nitride coating and grease, the high-entropy nitride coating includes a Cr transition layer and a CrAlVTiNbN high-entropy nitride coating, and the high-entropy nitride coating is prepared using high-power pulsed magnetron sputtering technology.

[0019] A method for preparing a high-entropy nitride coating, comprising the following specific steps: (1) Pretreatment The 9Cr18 bearing steel substrate was ultrasonically cleaned with anhydrous ethanol and petroleum ether for 30 min, respectively, and then dried and placed in a dry chamber for standby; (2) Pre-sputtering cleaning The steel block sample treated in step (1) was placed in a vacuum chamber, the chamber was heated, the temperature was set to 350℃, and when the vacuum degree was lower than 0.001 Pa, the ion etching of the substrate surface was started, Ar was introduced, the flow rate was 350 sccm, the etching gas pressure was 1.1 Pa, a pulsed bias voltage was applied to the steel block sample, the bias voltage was -800 V, the frequency was 40 kHz, the pulse width was 4 μs, and the steel block sample was pre-sputtered and cleaned with Ar plasma for 20-30 min; (3) Depositing a Cr transition layer A high-power pulsed magnetron sputtering technology was adopted, the Ar flow rate was adjusted to 60 sccm, the pulsed bias voltage was adjusted to -200 V, a high-power pulsed power source was applied to the pure Cr target, the peak current was adjusted to 240 A, the frequency was 100 Hz, the pulse width was 300 μs, a Cr transition layer was deposited, and the deposition time was 10 min; (4) Depositing a CrAlVTiNbN high-entropy nitride coating, wherein the atomic proportions of the elements in the high-entropy nitride coating are 0.2Cr-0.09Al-0.07V-0.05Ti-0.04Nb-0.55N, and the thickness is 0.7 μm.

[0020] A high-power pulsed magnetron sputtering technology was adopted, the peak current of the CrAlVTiNb alloy target was 240 A, the frequency was 100 Hz, the pulse width was 300 μs, the Ar flow rate was kept unchanged, N2 was introduced at a flow rate of 20 sccm, a pulsed bias voltage was applied to the steel block sample, the bias voltage was -120 V, the frequency was 40 kHz, the pulse width was 12 μs, the deposition time was 180 min, and a CrAlVTiNbN coating was deposited.

[0021] Reference Figure 1The high-entropy nitride coating of Example 1 was matched with grease to test the tribological performance under different loads by using a high-temperature friction tester to simulate the atmospheric environment. The grease was prepared according to the patent CN112899053A, and the formula of the grease was that a special high-temperature chain oil was used as a base oil, and the grease was prepared by thickening treatment of a urea-based thickening agent. The urea-based thickening agent has excellent high-temperature stability, can maintain the structural integrity and lubricating performance of the grease under high-temperature working conditions, and can further improve the oxidation resistance and volatility resistance of the grease in a high-temperature environment, which is suitable for the use requirements of the coating in a high-temperature friction scene. The lubricating grease was applied by direct application.

[0022] The heating device was turned on, and the friction experiment was started when the environmental temperature reached 350 DEG C. The friction time of each experiment was 30 minutes. The average friction coefficient of the lubricating system was 0.054 under a load of 5 N during the friction process. The average friction coefficient of the lubricating system was 0.035 under a load of 30 N and a rotation speed of 300 r / min during the friction process, and the friction coefficient was as low as 0.006. The average friction coefficient of the lubricating system was 0.145 under a load of 40 N during the friction process.

[0023] The high-entropy nitride coating of the present application was subjected to a high-temperature friction experiment at 350 DEG C without the lubricating grease, and the average friction coefficient was 0.4 (not shown).

[0024] Comparative Example 1 The lubricating grease of Example 1 was replaced by a commercially available Lubemater CH-51, and the rest remained unchanged. The application method was consistent with that of Example 1, and the lubricating oil was applied by direct application to ensure that the contact area between the coating and the friction pair was completely covered with the lubricating oil.

[0025] Reference Figure 2 The coating of Example 1 and the lubricating oil system were subjected to a tribological performance test by using a high-temperature friction tester. The heating device was turned on, and the friction experiment was started when the environmental temperature reached 350 DEG C. The average friction coefficient was about 0.38 under a load of 30 N and a rotation speed of 300 r / min during the friction process.

[0026] Comparative Example 2 Reference Figure 3 The 9Cr18 steel substrate and the lubricating grease of Example 1 were subjected to a tribological performance test by using a high-temperature friction tester. The heating device was turned on, and the friction experiment was started when the environmental temperature reached 350 DEG C. The average friction coefficient was about 0.04 under a load of 30 N and a rotation speed of 300 r / min during the first 26 minutes of the friction process, and then the lubrication failed, and the maximum friction coefficient was about 0.4.

[0027] From the lubrication mechanism, the base oil type of the grease (such as mineral oil, synthetic oil), the thickener type (such as urea-based, lithium-based, calcium-based) and the additive composition (such as anti-wear agent, extreme pressure agent) will directly affect its lubricating effect, so when replacing different types of lubricating grease, the friction coefficient between the coating and the friction pair will usually change significantly. Through previous experimental verification, except for the high-temperature lubricating grease specially prepared in the laboratory (i.e. the lubricating grease prepared in the patent with publication number CN112899053A), other conventional lubricating greases applied to the coating all have the problem of too high friction coefficient, which cannot meet the demand of low friction working condition, so the specially prepared high-temperature lubricating grease is the preferred lubricating medium for the current coating.

[0028] The performance of the coating of the present application on 9Cr18 and 8Cr4Mo4V steel is consistent, and the bearing steel can be selected from 9Cr18 steel or 8Cr4Mo4V steel.

[0029] The above is the preferred embodiment of the present application, it should be pointed out that for the ordinary skilled in the art, without departing from the principles of the present application, can also make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A low friction solid / grease lubrication system characterized in that, The solid / grease lubricating system is composed of a high-entropy nitride coating and a lubricating grease, the high-entropy nitride coating comprises a Cr transition layer and a CrAlVTiNbN high-entropy nitride coating, the atomic ratio of each element in the CrAlVTiNbN high-entropy nitride coating is 0.2Cr-0.09Al-0.07V-0.05Ti-0.04Nb-0.55N, the CrAlVTiNbN high-entropy nitride coating is prepared by using a high-power pulsed magnetron sputtering technology, and the lubricating grease is a tetraurea lubricating grease.

2. The low friction solid / grease lubrication system of claim 1, wherein, The friction coefficient of the solid / grease lubricating system in an atmosphere at 350 DEG C is 0.

006.

3. The method of making a low friction solid / grease lubrication system of claim 1, wherein, The preparation method of the high-entropy nitride coating comprises the following steps: (1) Pretreatment The substrate is ultrasonically cleaned for 30 min, dried and then placed in a dry cavity for standby; (2) Pre-sputtering cleaning The substrate treated in step (1) is placed in a vacuum chamber, vacuumized, heated, and when the temperature is set to 350 DEG C and the vacuum degree is lower than 0.001 Pa, ion etching is started on the surface of the substrate, Ar is introduced at a flow rate of 350 sccm, the etching gas pressure is 1.1 Pa, a pulsed bias voltage is applied to the substrate, the bias voltage is -800 V, the frequency is 40 kHz, the pulse width is 4 mu s, and the substrate is pre-sputtered and cleaned by Ar plasma for 20-30 min; (3) Depositing a Cr transition layer A high-power pulsed magnetron sputtering technology is used, the Ar flow rate is adjusted to 60 sccm, the pulsed bias voltage is adjusted to -200 V, a high-power pulsed power supply is applied to a pure Cr target, the peak current is adjusted to 240 A, the frequency is 100 Hz, the pulse width is 300 mu s, a Cr transition layer is deposited, and the deposition time is 10 min; (4) Depositing a CrAlVTiNbN high-entropy nitride coating A high-power pulsed magnetron sputtering technology is used, the peak current of a CrAlVTiNb alloy target is 240 A, the frequency is 100 Hz, the pulse width is 300 mu s, the Ar flow rate is kept unchanged, N2 is introduced at a flow rate of 20 sccm, a pulsed bias voltage is applied to the substrate, the bias voltage is -120 V, the frequency is 40 kHz, the pulse width is 12 mu s, the deposition time is 180 min, and a CrAlVTiNbN coating is deposited.

4. The method of using a low friction solid / grease lubrication system of claim 1, wherein, The tetraurea lubricating grease is uniformly and continuously coated on the surface of the CrAlVTiNbN high-entropy nitride coating.

5. Use of a low friction solid / grease lubrication system according to claim 1, characterized in that, The low-friction solid / grease lubricating system is used for aviation special materials.

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