A multi-layer Ni3Al-based self-lubricating coating and its preparation method

Abstract

The present invention relates to a multi-layer Ni3Al-based self-lubricating coating and a preparation method thereof, which uses Ni3Al alloy as a matrix, and uses Sn-Ag-Cu and Ti3AlC2 as a lubricating phase and a reinforcing phase respectively; a Ni3Al-based self-lubricating coating with a multi-layer structure of alternating soft and hard is prepared by a laser cladding method from Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2, wherein from the top layer to the bottom layer, the hard coating, soft coating, hard coating and soft coating are respectively deposited, and the soft and hard coating are alternately deposited twice. Wherein, the masses of Sn-Ag-Cu and Ti3AlC2 contained in the hard coating are (7.0-9.0)wt.% and (10.0-12.0)wt.% of the mass of the Ni3Al alloy respectively, and the masses of Sn-Ag-Cu and Ti3AlC2 contained in the soft coating are (9.0-11.0)wt.% and (8.0-10.0)wt.% of the mass of the Ni3Al alloy respectively. The multi-layered Ni3Al-based self-lubricating coating combines the advantages of hard and soft coatings by alternating the deposition of soft and hard coatings, so that the coating has both high hardness and low stress, thereby effectively reducing the friction coefficient and wear rate of the coating material during sliding, and making the prepared Ni3Al-based self-lubricating coating have stable and excellent tribological properties.

Description

Technical Field

[0001] The invention relates to a Ni3Al-based self-lubricating coating with a multilayer structure using Sn-Ag-Cu and Ti3AlC2 as a lubricating phase and a reinforcing phase respectively, and a preparation method thereof. Background Art

[0002] Most mechanical systems experience friction and wear during contact. The rapid development of high-tech industries such as aviation, aerospace, nuclear engineering, and energy and power has placed increasingly stringent requirements on the lubrication performance of materials used in demanding operating conditions, such as high temperatures, wide temperature ranges, and heavy loads. High-temperature solid self-lubricating coatings can provide a high-performance solid lubricating film on the interface of friction pairs in high-temperature environments, resolving the failure of traditional lubricants in high-temperature environments, ensuring reliable operation of friction pairs in high-temperature environments, and reducing energy loss. In recent years, they have become a hot topic in the field of tribology and have experienced rapid development.

[0003] As a high-temperature structural material, Ni3Al intermetallic compounds have been widely used in aviation, metallurgy, machinery, building materials and other fields due to their high melting point, high creep strength, corrosion resistance and high-temperature oxidation resistance. However, the room temperature plasticity and fracture toughness of Ni3Al intermetallic compounds are low, which limit their application in industry. Therefore, it is very important to further improve the tribological properties of Ni3Al intermetallic compounds under harsh conditions to meet the requirements of industrial use. The strength and wear resistance of the alloy can be effectively improved through material composite technology. However, traditional reinforcing particles have poor wettability with the Al matrix, and the improvement of tribological properties is obviously insufficient. Therefore, the design and development of new reinforcing phases has become one of the key factors to further improve the tribological properties of Ni3Al alloys.

[0004] Generally speaking, the wear resistance of a material surface is positively correlated with its hardness properties. Based on this, in order to obtain excellent wear resistance, researchers are committed to preparing high-hardness wear-resistant coatings. However, due to many problems such as high internal stress and fatigue crack initiation in hard coatings, the coating thickness and service life are limited. In response to my country's economic and social development requirements of energy conservation, efficiency improvement, emission reduction and environmental protection, higher requirements are also placed on the friction reduction and wear resistance of advanced engineering materials under harsh working conditions. Therefore, selecting a suitable reinforcing phase with excellent reinforcing effect on the Ni3Al matrix and developing a coating material with both good toughness and self-lubricating effect are technical problems that need to be solved urgently in this field. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned prior art and to provide a Ni3Al-based self-lubricating coating with a multilayer structure having Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and reinforcing phase, respectively, and a preparation method thereof, so as to effectively exert the friction-reducing and wear-resistant effects of the lubricating phase Sn-Ag-Cu alloy and the reinforcing phase Ti3AlC2, thereby reducing the friction coefficient and wear rate of the material during sliding, so that the prepared Ni3Al-based self-lubricating coating has stable and excellent tribological properties.

[0006] The technical solution adopted by the present invention to solve the above-mentioned problems is:

[0007] A multi-layer Ni3Al-based self-lubricating coating comprises, from the top layer to the bottom layer, a hard coating, a soft coating, a hard coating, and a soft coating (the soft and hard coatings are deposited alternately twice), with the top hard coating serving as the contact surface with the grinding pair. Each layer uses a Ni3Al alloy as a matrix, and uses a Sn-Ag-Cu alloy and Ti3AlC2 as lubricating and reinforcing phases. The hard coating contains 7.0-9.0 wt.% and 10.0-12.0 wt.% of the Ni3Al alloy by weight and the soft coating contains 9.0-11.0 wt.% and 8.0-10.0 wt.% of the Ni3Al alloy by weight.

[0008] According to the above solution, the total thickness of the multi-layer Ni3Al-based self-lubricating coating is 600-800 μm, wherein the thickness of the hard coating and the soft coating are both 150-200 μm.

[0009] According to the above scheme, the base material Ni3Al alloy mainly includes the elements Ni, Al, Mo and Cr. Preferably, the base material Ni3Al alloy in the present invention comprises the following elements by mass percentage: Al 8.0-8.5%, Mo 6.5-7.0%, Cr 5.5-6.0%, Zr 0.2-0.3%, B 0.03-0.05%, and the balance Ni.

[0010] According to the above scheme, the mass ratio of the elements Sn, Ag, and Cu in the Sn-Ag-Cu alloy is (55-60): (25-35): (10-15).

[0011] The present invention uses Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 to prepare a Ni3Al-based self-lubricating coating with a multilayer structure of alternating soft and hard layers on the surface of 1Cr18Ni9Ti stainless steel by using an ultrasonic vibration-assisted laser cladding method. The specific preparation method is as follows: Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 is selected and added to a powder feeding device, and sintered into a metal liquid at a high temperature of a laser using an ultrasonic vibration-assisted laser cladding process. Then, a soft coating, a hard coating, a soft coating, and a hard coating are prepared from the bottom layer to the top layer in a layer-by-layer stacking manner, and the soft and hard layers are alternately deposited twice, thereby obtaining a Ni3Al-based self-lubricating coating with a multilayer structure having Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and the reinforcing phase, respectively. Among them, the powder output method of the powder feeding equipment is coaxial powder feeding; the laser cladding process is: laser power 2.0-2.2kW, spot diameter 1.5-2.0mm, scanning speed 400-500mm / min, powder feeding speed 20-25g / min; the characteristic parameters of ultrasonic vibration are: ultrasonic frequency 20-25kHz, amplitude 15-20μm.

[0012] In the above scheme, the Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 is prepared by gas atomization technology, and its preparation method mainly includes the following steps:

[0013] 1) Ni powder, Al powder, Mo powder, and Cr powder are selected as matrix raw material powders according to the mass percentage of each element in the Ni3Al-based alloy; Sn powder, Ag powder, and Cu powder are selected as Sn-Ag-Cu alloy raw material powders according to the mass ratio of the elements in the Sn-Ag-Cu alloy; Sn-Ag-Cu alloy raw material powder and ternary layered ceramic Ti3AlC2 powder are selected as lubricating phase and reinforcing phase, respectively, at (7.0-11.0) wt.% and (8.0-12.0) wt.% of the total weight of the matrix raw material powder; and the matrix powder, lubricating phase, and reinforcing phase powders are fully mixed;

[0014] 2) melting the fully mixed powder obtained in step 1) under the protection of an inert gas to obtain a molten alloy liquid;

[0015] 3) The molten alloy liquid is atomized, and the atomized molten droplets are cooled and solidified to form spherical metal powder, which is the desired Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2.

[0016] In the above scheme, the powder mixing in step 1) is performed by vibration mixing; wherein the vibration frequency is 45-55 Hz, the vibration force is 11000-12000 N, and the oscillation time is 30-40 min.

[0017] In the above scheme, the inert gas in step 2) is preferably nitrogen or the like. Before the inert gas is filled, the chamber is pre-evacuated to a vacuum degree of <0.06 MPa; after the inert gas is filled, the oxygen content is <100 ppm.

[0018] In the above scheme, the melting temperature in step 2) is 1050-1150° C., and the holding time is 25-35 minutes.

[0019] In the above scheme, the specific method of atomization in step 3) is as follows: first, start the atomizing disk. After the atomizer is operating normally, open the liquid release valve to release the molten alloy liquid onto the atomizing disk. The disk is set to high-speed rotation, and the molten alloy liquid is atomized in the atomizer. The rotation speed of the disk is 30,000-40,000 rpm; the flow rate of the molten alloy liquid is 1.0-1.4 kg / min.

[0020] In the above scheme, the Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 required in step 3) is screened, and the particle size is preferably controlled within the range of 53-105 μm.

[0021] The Ni3Al-based self-lubricating coating with a multilayer structure of Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and reinforcing phase, respectively, was subjected to friction tests. The results showed that it exhibited excellent tribological properties during the friction and wear process, with a small friction coefficient (average value of about 0.18-0.21) and a wear rate of (2.1-2.4)×10 -5 mm 3 N -1 m -1 .

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. In the multilayer Ni3Al-based self-lubricating coating, the hard coating has a hardness of 6.78-6.92GPa, and the soft coating has a hardness of 5.81-5.95GPa. Due to the alternating deposition of the hard and soft coatings, the stress concentration in the hard coating during friction and wear can be effectively relieved in the adjacent soft coating. This alternating hard and soft multilayer structure greatly improves the material spalling caused by excessive stress in the hard coating during friction and wear, enhances the coating's toughness, and significantly improves the wear resistance of the Ni3Al-based coating, resulting in the prepared multilayer Ni3Al-based self-lubricating coating having stable and excellent tribological properties.

[0024] 2. The ternary layered ceramic Ti3AlC2 combines many excellent properties of both metals and ceramics. The excellent self-lubricity resulting from its layered structure helps improve the wear resistance of the composite material. At high temperatures, the low-energy Al atoms in the Ti3AlC2 lattice partially escape, forming a well-wetting interface with the Ni3Al matrix, which also contains the alloying element Al. These unique advantages give Ti3AlC2 an excellent reinforcing effect on the Ni3Al matrix.

[0025] 3. The present invention uses ultrasonic vibration-assisted laser cladding to prepare a multilayer Ni3Al-based self-lubricating coating. During the laser cladding process, the ultrasonic cavitation and acoustic streaming effects generated by the ultrasonic vibration promote the refinement and homogenization of the microstructure of the laser-clad coating material, thereby significantly improving the microhardness of the laser-clad coating and significantly enhancing the wear resistance of the multilayer Ni3Al-based self-lubricating coating.

[0026] 4. The preparation method of the present invention is simple and novel. The process parameters required for preparing Ni3Al-based spherical powder and multi-layer Ni3Al-based self-lubricating coating are easy to control and highly operable. In addition, under the premise of ensuring that the self-lubricating material has excellent friction reduction and wear resistance, the composite lubricating phase Sn-Ag-Cu is used to replace the traditional more expensive lubricating phase Ag, which effectively reduces the manufacturing cost of the self-lubricating material and is suitable for large-scale and wide applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a preparation process flow chart of the present invention.

[0028] Figure 2 This is a scanning electron microscope photograph of the Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 prepared in Example 1 of the present invention, with a magnification of 800 times.

[0029] Figure 3 This is an electron probe photograph of the wear scar obtained after a friction and wear test of a multilayer Ni3Al-based self-lubricating coating having Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and reinforcing phase, respectively, prepared in Example 2 of the present invention.

[0030] Figure 4 The friction coefficient test results of a Ni3Al-based self-lubricating coating with a multilayer structure of Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and the reinforcing phase prepared in Examples 1, 2 and 3 of the present invention were tested at room temperature. The test conditions were: load 10N, sliding speed 0.2m / s, test temperature room temperature 25°C, time 60min, and friction radius 5mm.

[0031] Figure 5The wear rate test results of a Ni3Al-based self-lubricating coating with a multilayer structure of Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and the reinforcing phase prepared in Examples 1, 2 and 3 of the present invention were tested at room temperature. The test conditions were: load 10N, sliding speed 0.2m / s, test temperature room temperature 25°C, time 60min, and friction radius 5mm. DETAILED DESCRIPTION

[0032] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with examples, but the present invention is not limited to the following examples.

[0033] In the following examples, a multilayered Ni3Al-based self-lubricating coating comprising Sn-Ag-Cu and Ti3AlC2 as the lubricating and reinforcing phases, respectively, is prepared from Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2. The present invention provides a specific preparation method, but is not limited thereto. Ni3Al-based spherical powders containing Sn-Ag-Cu and Ti3AlC2 and multilayered Ni3Al-based self-lubricating coatings prepared by other methods that meet the requirements of the present invention also fall within the scope of protection of the present invention.

[0034] The present invention provides a method for preparing Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2, comprising the following steps:

[0035] 1) Selecting Ni powder, Al powder, Mo powder, and Cr powder as matrix raw material powders according to the mass percentage of each element in the Ni3Al-based alloy; selecting Sn powder, Ag powder, and Cu powder as Sn-Ag-Cu alloy raw material powders according to the mass ratio of the elements in the Sn-Ag-Cu alloy; selecting Sn-Ag-Cu alloy raw material powder and Ti3AlC2 powder as lubricating phase and reinforcing phase according to (7.0-11.0) wt.% and (8.0-12.0) wt.% of the total mass of the matrix raw material powder, respectively; and thoroughly mixing the matrix powder, lubricating phase powder, and reinforcing phase powder;

[0036] 2) After the smelting chamber and the atomizing chamber are evacuated to a predetermined vacuum degree, an inert protective gas is introduced to adjust the ambient oxygen content to a predetermined value; the fully mixed powder obtained in step 1) is added to a high-temperature smelting furnace to be melted into a molten alloy liquid;

[0037] 3) starting the atomizing turntable, and after the atomizer is operating normally, opening the liquid release valve to place the molten alloy liquid obtained in step 2) onto the atomizing turntable, and rotating the turntable at high speed; atomizing the molten alloy liquid in the atomizer, and the atomized droplets cool and solidify in the atomization chamber to form spherical metal powder;

[0038] 4) Collect the metal powder in a receiving tank, and after the spherical metal powder is fully cooled to room temperature, sieve it according to the particle size requirements to obtain the required Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2.

[0039] Among them, the vibration frequency used for vibration mixing is 45-55Hz, the vibration force is 11000-12000N, and the oscillation time is 30-40 minutes; the predetermined vacuum degree is <0.06MPa, the inert protective gas is nitrogen, the predetermined oxygen content is <100ppm, the high-temperature melting furnace temperature is 1050-1150℃, and the holding time is 25-35min; the rotating disk speed is 30000-40000r / min, and the molten alloy liquid flow rate is 1.0-1.4kg / min; the spherical powder particle size requirement is 53-105μm.

[0040] Depend on Figure 2 It can be seen that the Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 prepared above is a single-particle spherical powder with a diameter of 53-105 μm, which meets the powder particle size requirements required for laser melting.

[0041] Example 1

[0042] A multilayer Ni3Al-based self-lubricating coating with Sn-Ag-Cu and Ti3AlC2 as lubricating phase and reinforcing phase, respectively, was prepared on the surface of 1Cr18Ni9Ti stainless steel. From the top layer to the bottom layer, they are hard coating, soft coating, hard coating and soft coating, respectively, and the thickness of each layer is 150μm. Each layer is based on Ni3Al alloy, and Sn-Ag-Cu and Ti3AlC2 are used as lubricating phase and reinforcing phase; the elements in the matrix material Ni3Al alloy are calculated by mass percentage as follows: Al 8.0%, Mo 6.5%, Cr5.5%, Zr 0.2%, B 0.03%, Ni 79.77%; the mass ratio of Sn, Ag, and Cu in the lubricating phase Sn-Ag-Cu alloy is 55:35:10; the mass of Sn-Ag-Cu in the hard coating and soft coating is 7.0wt.% and 9.0wt.% of the Ni3Al mass, respectively; the mass of Ti3AlC2 in the hard coating and soft coating is 10.0wt.% and 8.0wt.% of the Ni3Al mass, respectively.

[0043] like Figure 1 As shown, the multilayered Ni3Al-based self-lubricating coating with Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and the reinforcing phase, respectively, is prepared from Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2, and the preparation method specifically comprises the following steps:

[0044] 1) According to the mass percentage of each element in the Ni3Al-based alloy, 797.7 g of Ni powder, 80 g of Al powder, 65 g of Mo powder, 55 g of Cr powder, 2 g of Zr powder, and 0.3 g of B powder were selected; according to the mass ratio of each element in the Sn-Ag-Cu alloy, 49.5 g of Sn powder, 31.5 g of Ag powder, and 9 g of Cu powder were selected; and according to the Ti3AlC2 addition ratio, 80 g of Ti3AlC2 powder was selected; the Ni powder, Al powder, Mo powder, Cr powder, Zr powder, B powder, Sn powder, Ag powder, Cu powder, and Ti3AlC2 powder were mixed to obtain a first batch for preparing a soft coating;

[0045] According to the mass percentage of each element in the Ni3Al-based alloy, 797.7 grams of Ni powder, 80 grams of Al powder, 65 grams of Mo powder, 55 grams of Cr powder, 2 grams of Zr powder, and 0.3 grams of B powder were selected; according to the mass ratio of each element in the Sn-Ag-Cu alloy, 38.5 grams of Sn powder, 24.5 grams of Ag powder, and 7 grams of Cu powder were selected; according to the addition ratio of Ti3AlC2, 100 grams of Ti3AlC2 powder was selected; the Ni powder, Al powder, Mo powder, Cr powder, Zr powder, B powder, Sn powder, Ag powder, Cu powder, and Ti3AlC2 powder were mixed to obtain a second ingredient for preparing a hard coating;

[0046] The obtained ingredients 1 and 2 are subjected to subsequent steps 2)-5) respectively to obtain the desired two Ni3Al-based spherical powders containing different amounts of Sn-Ag-Cu and Ti3AlC2;

[0047] 2) Dry mix the above ingredients separately in a vibrating mixer with a steel outer tank and a polytetrafluoroethylene inner tank. The vibration frequency is 45 Hz, the vibration force is 11000 N, and the oscillation time is 30 minutes. After the powders are fully mixed, add them to the melting furnace.

[0048] 3) The melting chamber and the atomizing chamber were evacuated to a vacuum of <0.06 MPa and filled with inert nitrogen gas to reduce the ambient oxygen content to <100 ppm; the fully mixed powder obtained in step 2) was added to a high-temperature melting furnace to melt into a molten alloy liquid at a temperature of 1050° C. for 25 minutes;

[0049] 4) starting the atomizing turntable. After the atomizer is operating normally, opening the liquid release valve, placing the molten alloy liquid obtained in step 3) onto the atomizing turntable at a flow rate of 1.0 kg / min; rotating the turntable at a high speed of 30,000 rpm; atomizing the molten alloy liquid in the atomizer, and allowing the atomized droplets to cool and solidify in the atomization chamber to form metal powder;

[0050] 5) Collect the metal powder in a receiving tank, wait for the powder to fully cool to room temperature, and then sieve it according to the particle size range of 53-105 μm to obtain the required two Ni3Al-based spherical powders containing different amounts of Sn-Ag-Cu and Ti3AlC2;

[0051] 6) adding the Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 prepared from the batch 1 obtained in step 1) into the barrel (1) equipped with the laser cladding equipment, and adding the Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 prepared from the batch 2 obtained in step 1) into the barrel (2) equipped with the laser cladding equipment;

[0052] 7) A soft bottom coating layer was prepared by conveying Ni3Al-based spherical powder containing 9.0 wt.% Sn-Ag-Cu and 8.0 wt.% Ti3AlC2 from barrel (1). The laser cladding process employed a laser power of 2.0 kW, a spot diameter of 1.5 mm, a scanning rate of 400 mm / min, and a powder feed rate of 20 g / min. The characteristic parameters of the ultrasonic vibration were a frequency of 20 kHz and an amplitude of 15 μm. Laser sintering was performed to obtain a soft bottom coating layer with a thickness of 150 μm.

[0053] Ni3Al-based spherical powder containing 7.0 wt.% Sn-Ag-Cu and 10.0 wt.% Ti3AlC2 was conveyed from barrel (2) and a hard coating layer was formed on top of the pre-prepared base soft coating using the same laser cladding process and ultrasonic vibration characteristic parameters as in barrel (1). Laser sintering formed the secondary base hard coating layer, which had a thickness of 150 μm.

[0054] The self-lubricating coating consists of a soft coating, a hard coating, a soft coating, and a hard coating, alternating between soft and hard coatings, deposited twice. Using Ni3Al-based spherical powder containing 9.0 wt.% Sn-Ag-Cu and 8.0 wt.% Ti3AlC2 in barrel (1), a soft coating layer was deposited above the hard coating layer at the sub-bottom layer using the same laser cladding process and ultrasonic vibration characteristic parameters. Laser sintering resulted in a soft coating layer at the sub-surface layer with a thickness of 150 μm.

[0055] Using Ni3Al-based spherical powder containing 7.0wt.% Sn-Ag-Cu and 10.0wt.% Ti3AlC2 in barrel (2), a hard coating was prepared on top of the soft coating located on the subsurface layer according to the same laser cladding process and ultrasonic vibration characteristic parameters; after laser sintering, a hard coating located on the surface was obtained with a thickness of 150μm.

[0056] After preparing the soft coating, hard coating, soft coating and hard coating from the bottom layer to the top layer respectively, a multilayer Ni3Al-based self-lubricating coating with Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and reinforcing phase respectively is obtained.

[0057] After testing with an HVS-1000 digital microhardness tester, the Ni3Al-based self-lubricating coating with a multilayer structure prepared in Example 1, which has Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and reinforcing phase, respectively, has a surface hardness of 6.78 GPa and a relative density of 99.4%. Figure 4 and Figure 5 The results show that the friction coefficient of the Ni3Al-based self-lubricating composite material prepared in this embodiment is small (the average value is about 0.2), and the wear rate is 2.2×10 -5 mm 3 N -1 m -1 , showing excellent tribological properties.

[0058] Example 2

[0059] A multilayer Ni3Al-based self-lubricating coating with Sn-Ag-Cu and Ti3AlC2 as lubricating phase and reinforcing phase was prepared on the surface of 1Cr18Ni9Ti stainless steel. From the top layer to the bottom layer, it consists of hard coating, soft coating, hard coating and soft coating, and the thickness of each layer is 175μm. Each layer is based on Ni3Al alloy, with Sn-Ag-Cu and Ti3AlC2 as lubricating phase and reinforcing phase respectively; the elements in the matrix material Ni3Al-based alloy are calculated by mass percentage as follows: Al 8.25%, Mo 6.75%, Cr5.75%, Zr 0.25%, B 0.04%, and Ni 78.96%; the mass ratio of Sn, Ag, and Cu in the lubricating phase Sn-Ag-Cu alloy is 57.5:30:12.5; the mass of Sn-Ag-Cu in the hard coating and soft coating is 8.0wt.% and 10.0wt.% of the mass of Ni3Al, respectively; the mass of Ti3AlC2 in the hard coating and soft coating is 11.0wt.% and 9.0wt.% of the mass of Ni3Al, respectively.

[0060] like Figure 1 As shown, the multilayered Ni3Al-based self-lubricating coating with Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and the reinforcing phase, respectively, is prepared from Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2, and the preparation method specifically comprises the following steps:

[0061] 1) According to the mass percentage of each element in the Ni3Al-based alloy, 789.6 grams of Ni powder, 82.5 grams of Al powder, 67.5 grams of Mo powder, 57.5 grams of Cr powder, 2.5 grams of Zr powder, and 0.4 grams of B powder were selected; according to the mass ratio of each element in the Sn-Ag-Cu alloy, 57.5 grams of Sn powder, 30 grams of Ag powder, and 12.5 grams of Cu powder were selected; according to the Ti3AlC2 addition ratio, 90 grams of Ti3AlC2 powder was selected; Ni powder, Al powder, Mo powder, Cr powder, Zr powder, B powder, Sn powder, Ag powder, Cu powder, and Ti3AlC2 powder were mixed to obtain a first ingredient for preparing a soft coating;

[0062] According to the mass percentage of each element in the Ni3Al-based alloy, 789.6 grams of Ni powder, 82.5 grams of Al powder, 67.5 grams of Mo powder, 57.5 grams of Cr powder, 2.5 grams of Zr powder, and 0.4 grams of B powder were selected; according to the mass ratio of each element in the Sn-Ag-Cu alloy, 46 grams of Sn powder, 24 grams of Ag powder, and 10 grams of Cu powder were selected; according to the addition ratio of Ti3AlC2, 110 grams of Ti3AlC2 powder was selected; the Ni powder, Al powder, Mo powder, Cr powder, Zr powder, B powder, Sn powder, Ag powder, Cu powder, and Ti3AlC2 powder were mixed to obtain a second ingredient for preparing a hard coating;

[0063] The obtained ingredients 1 and 2 are subjected to subsequent steps 2)-5) respectively to obtain the desired two Ni3Al-based spherical powders containing different amounts of Sn-Ag-Cu and Ti3AlC2;

[0064] 2) Dry mix the above ingredients separately in a vibrating mixer with a steel outer tank and an inner polytetrafluoroethylene tank. The vibration frequency is 50 Hz, the vibration force is 11500 N, and the oscillation time is 35 minutes. After the powders are thoroughly mixed, add them to the melting furnace.

[0065] 3) The melting chamber and the atomizing chamber were evacuated to a vacuum of <0.06 MPa and filled with inert nitrogen gas to reduce the ambient oxygen content to <100 ppm; the fully mixed powder obtained in step 2) was added to a high-temperature melting furnace to melt into a molten alloy liquid at a temperature of 1100° C. for 30 minutes;

[0066] 4) Start the atomizing turntable. After the atomizer is operating normally, open the liquid release valve and place the molten alloy liquid onto the atomizing turntable at a flow rate of 1.2 kg / min. The turntable is rotated at a high speed of 35,000 r / min. The molten alloy liquid is atomized in the atomizer, and the atomized droplets cool and solidify in the atomization chamber to form metal powder.

[0067] 5) Collect the metal powder in a receiving tank, wait for the powder to fully cool to room temperature, and then sieve it according to the particle size range of 53-105 μm to obtain the required two Ni3Al-based spherical powders containing different amounts of Sn-Ag-Cu and Ti3AlC2;

[0068] 6) adding the Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 prepared from the batch 1 obtained in step 1) into the barrel (1) equipped with the laser cladding equipment, and adding the Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 prepared from the batch 2 obtained in step 1) into the barrel (2) equipped with the laser cladding equipment;

[0069] 7) A soft bottom coating layer was prepared by conveying Ni3Al-based spherical powder containing 10.0 wt.% Sn-Ag-Cu and 9.0 wt.% Ti3AlC2 from barrel (1). The laser cladding process employed a laser power of 2.1 kW, a spot diameter of 1.75 mm, a scanning rate of 450 mm / min, and a powder feed rate of 22.5 g / min. Ultrasonic vibration parameters employed a frequency of 22.5 kHz and an amplitude of 17.5 μm. Laser sintering resulted in a soft bottom coating layer with a thickness of 175 μm.

[0070] Ni3Al-based spherical powder containing 8.0 wt.% Sn-Ag-Cu and 11.0 wt.% Ti3AlC2 was conveyed from barrel (2) and a hard coating layer was formed on top of the pre-prepared base soft coating using the same laser cladding process and ultrasonic vibration characteristic parameters as in barrel (1). Laser sintering formed the secondary base hard coating layer, which had a thickness of 150 μm.

[0071] The self-lubricating coating consists of a soft coating, a hard coating, a soft coating, and a hard coating, alternating between soft and hard coatings, deposited twice. Using Ni3Al-based spherical powder containing 10.0 wt.% Sn-Ag-Cu and 9.0 wt.% Ti3AlC2 in barrel (1), a soft coating layer was deposited above the hard coating located at the sub-bottom layer using the same laser cladding process and ultrasonic vibration characteristic parameters. Laser sintering resulted in a soft coating layer at the sub-surface layer with a thickness of 175 μm.

[0072] Using Ni3Al-based spherical powder containing 8.0wt.% Sn-Ag-Cu and 11.0wt.% Ti3AlC2 in barrel (2), a hard coating was prepared on top of the soft coating located on the subsurface layer according to the same laser cladding process and ultrasonic vibration characteristic parameters; after laser sintering, a hard coating located on the surface was obtained with a thickness of 175μm.

[0073] After preparing the soft coating, hard coating, soft coating and hard coating from the bottom layer to the top layer respectively, a multilayer Ni3Al-based self-lubricating coating with Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and reinforcing phase respectively is obtained.

[0074] The surface hardness of the multilayer Ni3Al-based self-lubricating coating prepared in Example 2 with Sn-Ag-Cu and Ti3AlC2 as lubricating and reinforcing phases was 6.85 GPa and the relative density was 99.5% after testing with a HVS-1000 digital microhardness tester. Figure 3 The wear scar image of the multilayer Ni3Al-based self-lubricating coating obtained after the friction and wear test shows that the wear scar surface is smooth and flat. Figure 4 and Figure 5 It shows that the friction coefficient of the Ni3Al-based self-lubricating composite material prepared in Example 2 is small (the average value is about 0.18), and the wear rate is 2.1×10 -5 mm 3 N -1 m -1 , showing excellent tribological properties.

[0075] Example 3

[0076] A multilayer Ni3Al-based self-lubricating coating with Sn-Ag-Cu and Ti3AlC2 as lubricating phase and reinforcing phase, respectively, was prepared on the surface of 1Cr18Ni9Ti stainless steel. From the top layer to the bottom layer, it consists of hard coating, soft coating, hard coating and soft coating, and the thickness of each layer is 200 μm. Each layer is based on Ni3Al alloy as the matrix, and Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and reinforcing phase; the elements in the matrix material Ni3Al-based alloy are calculated by mass percentage as follows: Al 8.5%, Mo 7%, Cr 6%, Zr0.3%, B 0.05%, and Ni 78.15%; the mass ratio of Sn, Ag, and Cu in the lubricating phase Sn-Ag-Cu alloy is 60:25:15; the mass of Sn-Ag-Cu in the hard coating and soft coating is 9.0wt.% and 11.0wt.% of the Ni3Al mass, respectively; the mass of Ti3AlC2 in the hard coating and soft coating is 12.0wt.% and 10.0wt.% of the Ni3Al mass, respectively.

[0077] like Figure 1 As shown, the multilayered Ni3Al-based self-lubricating coating with Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and the reinforcing phase, respectively, is prepared from Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2, and the preparation method specifically comprises the following steps:

[0078] 1) According to the mass percentage of each element in the Ni3Al-based alloy, 781.5 grams of Ni powder, 85 grams of Al powder, 70 grams of Mo powder, 60 grams of Cr powder, 3 grams of Zr powder, and 0.5 grams of B powder were selected; according to the mass ratio of each element in the Sn-Ag-Cu alloy, 66 grams of Sn powder, 27.5 grams of Ag powder, and 16.5 grams of Cu powder were selected; and according to the Ti3AlC2 addition ratio, 100 grams of Ti3AlC2 powder was selected; Ni powder, Al powder, Mo powder, Cr powder, Zr powder, B powder, Sn powder, Ag powder, Cu powder, and Ti3AlC2 powder were mixed to obtain a first ingredient for preparing a soft coating;

[0079] According to the mass percentage of each element in the Ni3Al-based alloy, 781.5 grams of Ni powder, 85 grams of Al powder, 70 grams of Mo powder, 60 grams of Cr powder, 3 grams of Zr powder, and 0.5 grams of B powder were selected; according to the mass ratio of each element in the Sn-Ag-Cu alloy, 54 grams of Sn powder, 22.5 grams of Ag powder, and 13.5 grams of Cu powder were selected; according to the addition ratio of Ti3AlC2, 120 grams of Ti3AlC2 powder was selected; the Ni powder, Al powder, Mo powder, Cr powder, Zr powder, B powder, Sn powder, Ag powder, Cu powder, and Ti3AlC2 powder were mixed to obtain a second ingredient for preparing a hard coating;

[0080] The obtained ingredients 1 and 2 are subjected to subsequent steps 2)-5) respectively to obtain the desired two Ni3Al-based spherical powders containing different amounts of Sn-Ag-Cu and Ti3AlC2;

[0081] 2) Dry mix the above ingredients separately in a vibrating mixer with a steel outer tank and an inner polytetrafluoroethylene tank. The vibration frequency is 55 Hz, the vibration force is 12000 N, and the oscillation time is 40 minutes. After the powders are thoroughly mixed, add them to the melting furnace.

[0082] 3) Evacuate the melting chamber and atomizing chamber to a vacuum degree of <0.06MPa and fill with inert protective gas nitrogen to make the ambient oxygen content <100ppm; add the fully mixed powder into a high-temperature melting furnace to melt into molten alloy liquid. The high-temperature melting furnace temperature is 1150℃ and the holding time is 35min;

[0083] 4) Start the atomizing turntable. After the atomizer is operating normally, open the liquid release valve and release the molten alloy liquid onto the atomizing turntable at a flow rate of 1.4 kg / min. The turntable is rotated at a high speed of 40,000 rpm. The molten alloy liquid is atomized in the atomizer, and the atomized droplets cool and solidify in the atomization chamber to form metal powder.

[0084] 5) Collect the metal powder in a receiving tank, wait for the powder to fully cool to room temperature, and then sieve it according to the particle size range of 53-105 μm to obtain the required two Ni3Al-based spherical powders containing different amounts of Sn-Ag-Cu and Ti3AlC2;

[0085] 6) adding the Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 prepared from the batch 1 obtained in step 1) into the barrel (1) equipped with the laser cladding equipment, and adding the Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 prepared from the batch 2 obtained in step 1) into the barrel (2) equipped with the laser cladding equipment;

[0086] 7) A soft bottom coating layer was prepared by conveying Ni3Al-based spherical powder containing 11.0 wt.% Sn-Ag-Cu and 10.0 wt.% Ti3AlC2 from barrel (1). The laser cladding process employed a laser power of 2.2 kW, a spot diameter of 2 mm, a scanning rate of 500 mm / min, and a powder feed rate of 25 g / min. Ultrasonic vibration parameters employed a frequency of 25 kHz and an amplitude of 20 μm. Laser sintering resulted in a soft bottom coating layer with a thickness of 200 μm.

[0087] Ni3Al-based spherical powder containing 9.0 wt.% Sn-Ag-Cu and 12.0 wt.% Ti3AlC2 was conveyed from barrel (2) and a hard coating layer was formed on top of the pre-prepared base soft coating using the same laser cladding process and ultrasonic vibration characteristic parameters as in barrel (1). Laser sintering formed the secondary base hard coating layer, which had a thickness of 200 μm.

[0088] The self-lubricating coating consists of a soft coating, a hard coating, a soft coating, and a hard coating, alternating between soft and hard coatings, deposited twice. Using Ni3Al-based spherical powder containing 11.0 wt.% Sn-Ag-Cu and 10.0 wt.% Ti3AlC2 in barrel (1), a soft coating layer was deposited above the sub-bottom hard coating using the same laser cladding process and ultrasonic vibration characteristic parameters. Laser sintering resulted in a 200 μm thick sub-surface soft coating.

[0089] Using Ni3Al-based spherical powder containing 9.0wt.% Sn-Ag-Cu and 12.0wt.% Ti3AlC2 in barrel (2), a hard coating was prepared on top of the soft coating located on the subsurface layer according to the same laser cladding process and ultrasonic vibration characteristic parameters; after laser sintering, a hard coating located on the surface was obtained with a thickness of 200μm.

[0090] After preparing the soft coating, hard coating, soft coating and hard coating from the bottom layer to the top layer respectively, a multilayer Ni3Al-based self-lubricating coating with Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and reinforcing phase respectively is obtained.

[0091] The surface hardness of the multilayer Ni3Al-based self-lubricating coating prepared in Example 3 with Sn-Ag-Cu and Ti3AlC2 as lubricating and reinforcing phases was tested by an HVS-1000 digital microhardness tester. The hardness was 6.92 GPa, and the relative density was 99.6%. Figure 4 The figure shows the friction coefficient of the Ni3Al-based self-lubricating coating with a multilayer structure of Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and the reinforcing phase prepared in Example 3 of the present invention at room temperature. It can be seen that the friction coefficient of the self-lubricating composite material is relatively small (the average value is about 0.21). Figure 5 The wear rate of the multilayer Ni3Al-based self-lubricating coating prepared in Example 3 is 2.4×10 -5 mm 3 N -1 m -1 ). It can be seen that the Ni3Al-based self-lubricating composite material prepared in this embodiment with Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and reinforcing phase respectively exhibits excellent tribological properties.

[0092] According to the experimental results of the above three embodiments, it is shown that the Ni3Al-based self-lubricating coating with a multilayer structure of Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and reinforcing phase, respectively, exhibits excellent tribological properties during the friction and wear process, with a small friction coefficient (average value of about 0.18-0.21) and a small fluctuation range, and a wear rate of 2.1-2.4×10 -5 mm 3 N -1 m -1 .

[0093] In summary, the present invention selects Sn-Ag-Cu and Ti3AlC2 powders according to the addition ratio and adds them to the matrix powder Ni powder and Al powder, and adopts the process technology of vibration mixing, high temperature melting, and rotating disk centrifugal atomization to prepare a Ni3Al-based spherical powder material containing Sn-Ag-Cu and Ti3AlC2 with a single particle structure; then, ultrasonic vibration-assisted laser cladding is used to prepare a Ni3Al-based self-lubricating coating with a multilayer structure using Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and reinforcing phase, respectively. The Ni3Al-based self-lubricating coating with a multilayer structure using Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and reinforcing phase obtained by the present invention has high purity, good density, excellent tribological properties, and a low friction coefficient and wear rate during friction and wear; and the steps and methods involved in the preparation process are simple and convenient, and are suitable for large-scale batch production.

[0094] All the raw materials listed in the present invention can realize the present invention, and the upper and lower limit values ​​and interval values ​​of each raw material can realize the present invention. The upper and lower limit values ​​and interval values ​​of the process parameters of the present invention (such as temperature, rotation speed, laser power, powder feeding rate, ultrasonic frequency, amplitude, etc.) can realize the present invention. The embodiments are not listed one by one here.

[0095] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this field, several improvements and changes can be made without departing from the creative concept of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A multi-layer Ni3Al-based self-lubricating coating, characterized in that It consists of a hard coating, a soft coating, a hard coating, and a soft coating from top to bottom, with the top hard coating serving as the contact surface with the grinding pair. Each layer is based on a Ni3Al alloy, with Sn-Ag-Cu alloy and Ti3AlC2 serving as lubricating and reinforcing phases. The hard coating contains 7.0-9.0wt% and 10.0-12.0wt% of the Ni3Al alloy in terms of Sn-Ag-Cu alloy and Ti3AlC2, respectively. The soft coating contains 9.0-11.0wt% and 8.0-10.0wt% of the Ni3Al alloy in terms of Sn-Ag-Cu alloy and Ti3AlC2, respectively. The multilayer Ni3Al-based self-lubricating coating is prepared on the surface of 1Cr18Ni9Ti stainless steel by using Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 through ultrasonic vibration-assisted laser cladding. The specific preparation method is as follows: Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 is selected and added to a powder feeding device, and sintered into a metal liquid at a high temperature of the laser by an ultrasonic vibration-assisted laser cladding process. Then, a soft coating, a hard coating, a soft coating and a hard coating are prepared from the bottom layer to the top layer in a layer-by-layer stacking manner, and the soft and hard coatings are alternately deposited twice, thereby obtaining a multilayer Ni3Al-based self-lubricating coating with Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and the reinforcing phase respectively; wherein, the powder output mode of the powder feeding device is coaxial powder feeding; the laser cladding process is: laser power 2.0-2.2 kW, spot diameter 1.5-2.0 mm, scanning speed 400-500 mm / min, powder feeding speed 20-25 g / min; the characteristic parameters of ultrasonic vibration are: ultrasonic frequency 20-25 kHz, amplitude 15-20μm.

2. The multi-layer Ni3Al-based self-lubricating coating according to claim 1, characterized in that The total thickness of the multi-layer Ni3Al-based self-lubricating coating is 600-800 μm, wherein the thickness of the hard coating and the soft coating are both 150-200 μm.

3. The method for preparing a multilayer Ni3Al-based self-lubricating coating according to claim 1, characterized in that It is prepared by ultrasonic vibration-assisted laser cladding of Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2. The specific preparation method is as follows: Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 is selected and added to a powder feeding device, and sintered into a metal liquid at a high temperature of a laser by ultrasonic vibration-assisted laser cladding process. Then, a soft coating, a hard coating, a soft coating and a hard coating are prepared from the bottom layer to the top layer by layer stacking, and the soft and hard coatings are alternately deposited twice, thereby obtaining a multi-layer structure Ni3Al-based self-lubricating coating with Sn-Ag-Cu and Ti3AlC2 as the lubricating phase and the reinforcing phase respectively. The Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 has a particle size within the range of 53-105 μm and is composed of Ni3Al, Sn-Ag-Cu and Ti3AlC2. The laser cladding process parameters are: laser power of 2.0-2.2 kW, spot diameter of 1.5-2.0 mm, scanning speed of 400-500 mm / min, powder output mode of the powder feeding equipment is coaxial powder feeding, and the powder feeding speed is 20-25 g / min. The characteristic parameters of ultrasonic vibration are: ultrasonic frequency of 20-25 kHz and amplitude of 15-20 μm.

4. The method for preparing a multilayer Ni3Al-based self-lubricating coating according to claim 3, wherein the method for preparing the Ni3Al-based spherical powder containing Sn-Ag-Cu and Ti3AlC2 comprises the following steps: 1) Selecting elemental powders as matrix raw materials according to the mass percentage of each element in the Ni3Al-based alloy; weighing elemental powders according to the mass ratio of each element in the Sn-Ag-Cu alloy; selecting corresponding elemental powders of the Sn-Ag-Cu alloy and Ti3AlC2 powder as lubricating phase and reinforcing phase at (7.0-11.0) wt.% and (8.0-12.0) wt.% of the total mass of the matrix raw materials, respectively; and thoroughly mixing the matrix raw materials, corresponding elemental powders of the Sn-Ag-Cu alloy, and Ti3AlC2 powder; 2) melting the fully mixed powder obtained in step 1) at a high temperature under the protection of an inert gas to obtain a molten alloy liquid; 3) The molten alloy liquid is centrifugally atomized on a rotating disk, and the atomized droplets are cooled and solidified to form spherical metal powder, which is the desired Ni3Al-based spherical powder containing Sn-Ag-Cu alloy and Ti3AlC2.

5. The method for preparing a multi-layer Ni3Al-based self-lubricating coating according to claim 4, characterized in that The high-temperature melting process is as follows: vacuum degree <0.06 MPa, ambient oxygen content <100 ppm, melting temperature 1050-1150 °C, and holding time 25-35 min.

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