Wide-temperature-range wear-resistant self-lubricating coating on surface of titanium alloy and preparation method thereof

Abstract

The invention relates to a titanium alloy surface wide-temperature-range wear-resistant self-lubricating coating, which is composed of a NiCrAlY bonding layer and a NiCr-Cr3C2-based wide-temperature-range wear-resistant self-lubricating layer taking Ag, a submicron-scale BaF2 / CaF2 eutectic and MoS2 as lubricating phases, or is composed of a NiCrAlY bonding layer and a NiCr-Cr3C2-based wide-temperature-range wear-resistant self-lubricating layer taking the submicron-scale BaF2 / CaF2 eutectic as the lubricating phase, or is composed of a NiCrAlY bonding layer and a NiCr-Cr3C2-based wide-temperature-range wear-resistant self-lubricating layer taking the submicron-scale BaF2 / CaF2 eutectic as the lubricating phase. Meanwhile, the invention further discloses a preparation method of the coating. According to the invention, the problems of decomposition, oxidation and the like of a spraying powder raw material due to too high deposition temperature are effectively solved, and effective deposition of a multi-component submicron-scale solid lubricant in a coating preparation process and synergistic lubrication of the multi-component submicron-scale solid lubricant in a wide temperature range are realized; the obtained coating is compact in structure, the interface bonding between the coating and a substrate is good, and the coating shows excellent tribological performance in a wide temperature range from room temperature to 800 DEG C.

Description

Technical Field

[0001] The present invention relates to the technical field of surface lubrication and protection of materials, and particularly to a wide-temperature-range wear-resistant self-lubricating coating on the surface of a titanium alloy and a preparation method thereof. Background Art

[0002] Titanium alloys have been widely used in important fields such as aerospace, marine vessels, and nuclear power due to their low density, high specific strength, and excellent corrosion resistance. However, the friction and wear problems of titanium alloy mechanical components under service conditions such as high speed, heavy load, and high and low temperature alternation seriously affect the precision, reliability, and service life of the entire mechanical motion system. Therefore, the design, preparation, and application of a wide-temperature-range wear-resistant self-lubricating coating on the surface of a titanium alloy are of great significance for improving the performance of titanium alloy mechanical moving parts and extending their service life.

[0003] In the current research on surface protective coatings of titanium alloys and their preparation methods, Patent CN11020559B discloses a high-temperature-resistant self-lubricating coating on the surface of a titanium alloy and a preparation method thereof. This coating uses nickel-coated hexagonal boron nitride (Ni-hBN) as an alloying powder and forms a high-temperature-resistant lubricating coating with γ-Ni, TiN, NiTi, NiTi2, TiB, and hBN as the main phases through laser alloying. This coating exhibits excellent tribological properties. The literature "Elevated temperatures erosion wear behavior of HVOF sprayed WC-Co-Cr / Mo coatings on Ti6Al4V substrate" also reports the research results on the tribological properties of a high-velocity oxygen fuel flame spraying (HVOF) WC-Co-Cr / Mo coating on the surface of a titanium alloy Ti6Al4V substrate in the range of 200-800 °C.

[0004] In summary, existing high-temperature self-lubricating and wear-resistant coatings on the surface of titanium alloys are mostly prepared by technologies such as laser cladding and flame spraying. However, the inherent high-temperature deposition characteristics of such coating preparation technologies limit to a certain extent the design and preparation of multi-component submicron-scale lubricant powder raw materials required for the preparation of high-performance wide-temperature-range wear-resistant self-lubricating coatings. At the same time, the high-temperature deposition characteristics and thermal damage to materials will also have an adverse impact on the composition, structure, and properties of the substrate and coating materials. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a wide-temperature-range wear-resistant self-lubricating coating on the surface of a titanium alloy with excellent wide-temperature-range tribological properties.

[0006] Another technical problem to be solved by the present invention is to provide a preparation method for the wide-temperature-range wear-resistant self-lubricating coating on the surface of the titanium alloy.

[0007] To solve the above problems, a wide-temperature-range wear-resistant self-lubricating coating on the surface of a titanium alloy according to the present invention is characterized in that: the coating is composed of a NiCrAlY bonding layer and a NiCr-Cr3C2-based wide-temperature-range wear-resistant self-lubricating layer with Ag, sub-micron-scale BaF2 / CaF2 eutectic and MoS2 as lubricating phases, or is composed of a NiCrAlY bonding layer and a NiCr-Cr3C2-based wide-temperature-range wear-resistant self-lubricating layer with sub-micron-scale BaF2 / CaF2 eutectic as the lubricating phase.

[0008] A method for preparing a wide-temperature-range wear-resistant self-lubricating coating on the surface of a titanium alloy as described above includes the following steps: ⑴ Prepare spherical or quasi-spherical mixed lubricant spraying powder: ① Weigh BaF2 / CaF2 eutectic powder with a powder particle size of 100 - 900 nm, MoS2 powder with a particle size of 400 - 1000 nm, and Ni powder with a particle size of 300 - 800 nm respectively according to the mass percentages of 40 - 50 wt.%, 0 - 10 wt.%, and 40 - 50 wt.%, and mix them evenly to obtain a mixed powder; ② Add the mixed powder to an aqueous solution of polyvinyl alcohol and stir to form a uniform slurry; after the slurry is ball-milled by a low-energy ball mill and spray-dried and granulated, spherical or quasi-spherical mixed powder composed of sub-micron-scale BaF2 / CaF2 eutectic, MoS2 and Ni powder is obtained; ③ After the spherical or quasi-spherical mixed powder is subjected to sintering densification treatment in an Ar atmosphere environment and screened, spherical or quasi-spherical mixed lubricant spraying powder with a particle size of 13 - 59 μm and composed of sub-micron-scale BaF2 / CaF2 eutectic, MoS2 and Ni powder is obtained; ⑵ Prepare spraying powder raw materials: By mass percentage, mix 10 - 12.5 wt.% of the spherical or quasi-spherical mixed lubricant spraying powder, 0 - 12.5 wt.% of atomized Ag powder and the balance of NiCr-Cr3C2 powder evenly and then dry. The drying temperature is 75 - 85 °C and the drying time is 1 - 2 h, thus obtaining the spraying powder raw materials; ⑶ Use the detonation spraying technology to prepare a wide-temperature-range wear-resistant self-lubricating coating: On the surface of a Ti6Al4V titanium alloy substrate that has been pre-ground with sandpaper, sandblasted, ultrasonically cleaned with absolute ethanol and acetone and dried, first spray the gun empty 2 - 4 times, deposit the NiCrAlY alloy powder with a particle size of 22 - 63 μm on the surface of the Ti6Al4V titanium alloy substrate to form a bonding layer, spray continuously for 1 - 3 layers, and the deposition thickness is 50 - 100 μm; finally, deposit the spraying powder raw materials on the surface of the bonding layer to form a wear-resistant self-lubricating layer, spray continuously and repeat 20 - 25 layers, and control the deposition thickness within 350 - 550 μm, thus obtaining a wide-temperature-range wear-resistant self-lubricating coating.

[0009] In step ②, the mass concentration of the polyvinyl alcohol aqueous solution is 4.0 - 5.0 g / L. In step ②, the mass-to-volume ratio of the mixed powder to the polyvinyl alcohol aqueous solution is 1 g : 1 mL.

[0010] In step ②, the conditions for spray drying granulation refer to controlling the slurry flow rate after ball milling to be 18.0 - 22.0 mL / min, setting the inlet air temperature of the spray dryer to 220 - 230 °C, the outlet temperature to 100 - 105 °C, and the rotation frequency of the atomizer turntable to 35 - 40 Hz; after granulation is completed, the powder is placed in a vacuum drying oven and dried at 70 - 90 °C for 5 - 8 h.

[0011] In step ③, the conditions for sintering densification treatment refer to a sintering target temperature of 800 - 850 °C, a heating rate of 10 °C / min, and a holding time of 1 - 1.5 h.

[0012] In step ⑵, the particle size of the atomized Ag powder is 13 - 66 μm; the particle size of the NiCr-Cr3C2 powder is 8 - 62 μm, which is formed by mixing and sintering 25 wt.% 80Ni20Cr and 75 wt.% Cr3C2.

[0013] In step ⑶, the conditions for explosion spraying refer to a mixed gas of acetylene and propane as the fuel gas, oxygen as the combustion-supporting gas, nitrogen as the auxiliary gas, the spray gun barrel of the spraying equipment is a convergent-divergent barrel, the gas filling volume of the gun is 55%, the oxygen-fuel ratio is 1.17 : 1, the spraying frequency is 5 Hz, the spraying distance is 145 - 155 mm, the spraying angle is 90°, and the moving speed of the spray gun is 60 mm / s.

[0014] The present invention has the following advantages compared with the prior art: 1. The present invention uses explosion spraying technology to prepare a coating on the surface of a Ti6Al4V titanium alloy substrate, which consists of a NiCrAlY bonding layer and a NiCr-Cr3C2-based wide-temperature self-lubricating layer with BaF2 / CaF2 eutectic, MoS2, and Ag as lubricating phases, or a NiCr-Cr3C2-based wide-temperature wear-resistant self-lubricating layer with sub-micron-scale BaF2 / CaF2 eutectic as the lubricating phase. This coating effectively improves the tribological properties of the titanium alloy in a wide temperature range (room temperature - 800 °C).

[0015] 2. Compared with the existing NiCr-Cr3C2-based wide-temperature self-lubricating coating, the coating of the present invention uses spherical or quasi-spherical mixed powders composed of submicron-scale BaF2 / CaF2 eutectic, Ni and / or MoS2 and / or atomized Ag powder as the lubricating phase, realizing the design and preparation of a NiCr-Cr3C2-based wide-temperature wear-resistant self-lubricating coating with multi-component submicron-scale solid lubricants for synergistic lubrication.

[0016] 3. The present invention realizes the design and preparation of spherical or quasi-spherical mixed spraying powders composed of submicron-scale BaF2 / CaF2 eutectic, Ni and / or MoS2 through spray drying granulation technology combined with powder sintering process, providing a useful reference for the component and structure design of the spraying powder raw materials for the existing wide-temperature wear-resistant self-lubricating coating.

[0017] 4. The wide-temperature wear-resistant self-lubricating coating on the surface of the titanium alloy described in the present invention has uniform microstructure, good bonding between the coating and the substrate, and exhibits excellent tribological properties in the wide temperature range of room temperature to 800°C.

[0018] 5. Compared with the common coating preparation technologies, the coating preparation technology of the present invention is computer-controlled explosive spraying, and its deposition process can achieve precise control of the gas flow rate; the pulsed explosive spraying method has less thermal damage to the substrate and spraying powder materials, effectively solving problems such as decomposition, oxidation, and ablation of the powder raw materials due to excessive deposition temperature, and realizing the effective deposition of multi-component submicron-scale solid lubricants during the coating preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following further details the specific embodiments of the present invention in conjunction with the drawings.

[0020] Figure 1 SEM-EDS photograph of the cross-sectional microstructure of the NiCr-Cr3C2-BaF2 / CaF2-MoS2-Ag coating described in Example 2 of the present invention.

[0021] Figure 2 Friction coefficient curve (left) and wear rate magnitude (right) of the NiCr-Cr3C2-BaF2 / CaF2-MoS2-Ag coating described in Example 2 of the present invention in the wide temperature range (room temperature to 800°C). DETAILED DESCRIPTION OF THE INVENTION

[0022] A wide-temperature wear-resistant self-lubricating coating on the surface of a titanium alloy, which is composed of a NiCrAlY bonding layer and a NiCr-Cr3C2-based wide-temperature wear-resistant self-lubricating layer with Ag, submicron-scale BaF2 / CaF2 eutectic and MoS2 as the lubricating phase, or composed of a NiCrAlY bonding layer and a NiCr-Cr3C2-based wide-temperature wear-resistant self-lubricating layer with submicron-scale BaF2 / CaF2 eutectic as the lubricating phase.

[0023] Its preparation method comprises the following steps: Comprises the following steps: (1) Prepare spherical or quasi-spherical mixed lubricant spraying powder: ① Weigh BaF2 / CaF2 eutectic powder with a powder particle size of 100 - 900 nm, MoS2 powder with a particle size of 400 - 1000 nm, and Ni powder with a particle size of 300 - 800 nm respectively according to the mass percentages (g / g) of 40 - 50 wt.%, 0 - 10 wt.%, and 40 - 50 wt.%, and mix them evenly to obtain a mixed powder.

[0024] ② Add the mixed powder to an aqueous solution of polyvinyl alcohol with a mass concentration of 4.0 - 5.0 g / L. The mass-volume ratio (g / mL) of the mixed powder to the aqueous solution of polyvinyl alcohol is 1 g : 1 mL, and stir to form a homogeneous slurry; the slurry is first ball-milled by a low-energy ball mill and then spray-dried and granulated: control the flow rate of the ball-milled slurry at 18.0 - 22.0 mL / min, set the inlet air temperature of the spray dryer at 220 - 230 °C, the outlet temperature at 100 - 105 °C, and the rotation frequency of the atomizer turntable at 35 - 40 Hz; after granulation, place the powder in a vacuum drying oven and dry it at 70 - 90 °C for 5 - 8 h to obtain spherical or quasi-spherical mixed powder composed of sub-micron-scale BaF2 / CaF2 eutectic, MoS2, and Ni powder.

[0025] ③ Carry out sintering densification treatment on the spherical or quasi-spherical mixed powder in an Ar atmosphere environment under the conditions of a sintering target temperature of 800 - 850 °C, a heating rate of 10 °C / min, and a holding time of 1 - 1.5 h, and then screen to obtain spherical or quasi-spherical mixed lubricant spraying powder with a particle size of 13 - 59 μm composed of sub-micron-scale BaF2 / CaF2 eutectic, MoS2, and Ni powder.

[0026] (2) Prepare the raw materials for the spraying powder: By mass percentage (g / g), mix 10 - 12.5 wt.% spherical or quasi-spherical mixed lubricant spraying powder (Ni - BaF2 / CaF2 - MoS2), 0 - 12.5 wt.% atomized Ag powder (13 - 66 μm), and the balance NiCr - Cr3C2 powder (8 - 62 μm) evenly, and place them in a vacuum drying oven for drying. The drying temperature is 75 - 85 °C, and the drying time is 1 - 2 h to obtain the raw materials for the spraying powder.

[0027] The NiCr - Cr3C2 powder is obtained by mixing and sintering 25 wt.% 80Ni20Cr and 75 wt.% Cr3C2.

[0028] (3) Prepare a wide-temperature-range wear-resistant self-lubricating coating using explosion spraying technology: On the surface of a Ti6Al4V titanium alloy substrate that has been pre-treated by sandpaper grinding, sandblasting, ultrasonic cleaning with anhydrous ethanol and acetone, and drying, first spray the gun empty 2 - 4 times to preheat and clean the surface of the titanium alloy substrate, so as to improve the bonding strength between the coating and the substrate and the powder deposition efficiency. Deposit a NiCrAlY alloy powder with a particle size of 22 - 63 μm on the surface of the Ti6Al4V titanium alloy substrate for the bonding layer, spray continuously for 1 - 3 layers, and the deposition thickness is 50 - 100 μm; finally, deposit the wear-resistant self-lubricating layer on the surface of the bonding layer with the sprayed powder raw material, spray continuously and repeat 20 - 25 layers, and control the deposition thickness within 350 - 550 μm, then the wide-temperature-range wear-resistant self-lubricating coating is obtained.

[0029] The explosion spraying conditions refer to that the fuel gas is a mixed gas of acetylene and propane, the oxygen is the combustion-supporting gas, the nitrogen is the auxiliary gas, the barrel of the spraying equipment is a convergent-divergent barrel, the gas filling volume of the gun is 55%, the oxygen-fuel ratio is 1.17:1, the spraying frequency is 5 Hz, the spraying distance is 145 - 155 mm, the spraying angle is 90°, and the moving speed of the gun is 60 mm / s.

[0030] Example 1 A method for preparing a wide-temperature-range wear-resistant self-lubricating coating on the surface of a titanium alloy, comprising the following steps: (1) Prepare spherical or near-spherical mixed lubricant spraying powder: ① Weigh 100 g of BaF2 / CaF2 eutectic powder with a particle size of 100 - 900 nm and 100 g of Ni powder with a particle size of 300 - 800 nm using an electronic balance, and mix them evenly to obtain a mixed powder.

[0031] ② Add the mixed powder to 200 mL of a polyvinyl alcohol aqueous solution with a mass concentration of 4.0 g / L and stir into a uniform slurry; the slurry is ball-milled using a low-energy ball mill, and after the ball-milled slurry is spray-dried and granulated, spherical or near-spherical mixed powder composed of BaF2 / CaF2 eutectic and Ni powder is obtained.

[0032] Among them: The conditions for spray drying and granulation refer to that the flow rate of the slurry after low-energy ball milling is controlled at 18.0 - 20.0 mL / min, the inlet air temperature of the spray dryer equipment is set at 230 °C, the outlet temperature is set at 100 °C, and the rotation frequency of the atomizer turntable is 40 Hz; after the granulation is completed, place the powder in a vacuum drying oven and dry at 70 °C for 8 h.

[0033] ③ The spherical or near-spherical mixed powder is densified and sintered in an Ar atmosphere. The target sintering temperature is 850 °C, the heating rate is 10 °C / min, and the holding time is 1 h. After sintering and screening, spherical or near-spherical mixed lubricant spraying powder composed of BaF2 / CaF2 eutectic and Ni powder with a particle size of 13 - 55 μm is obtained.

[0034] ⑵ Prepare the raw materials for the spraying powder: Use an electronic balance to accurately weigh 10 g of spherical or near-spherical mixed lubricant spraying powder and 90 g of NiCr-Cr3C2 powder. After mixing evenly, dry them in a vacuum drying oven at 75 °C for 2 h to obtain the raw materials for the spraying powder.

[0035] ⑶ Prepare the NiCr-Cr3C2-BaF2 / CaF2 coating on the titanium alloy surface by explosion spraying technology: On the surface of the Ti6Al4V titanium alloy substrate that has been pre-treated by sandpaper grinding, sandblasting, ultrasonic cleaning with anhydrous ethanol and acetone, and drying, first spray the gun empty 4 times to preheat and clean the surface of the titanium alloy substrate; then deposit the NiCrAlY alloy powder with a particle size of 22 - 63 μm on the surface of the Ti6Al4V titanium alloy substrate for the bonding layer, spray 1 layer, and the deposition thickness is about 50 μm; finally, deposit the raw materials for the spraying powder on the surface of the bonding layer for the wear-resistant self-lubricating layer, continuously repeat spraying 20 layers, and the deposition thickness is about 350 μm.

[0036] The explosion spraying conditions refer to a mixed gas of acetylene and propane as the fuel gas, oxygen as the combustion-supporting gas, nitrogen as the auxiliary gas, the gas filling volume of the gun is 55%, the oxygen-fuel ratio is 1.17:1, the spraying frequency is 5 Hz, the spraying distance is 155 mm, the spraying angle is 90°, and the moving speed of the gun is 60 mm / s.

[0037] Polish the surface of the prepared coating and then characterize the friction and wear properties of the coating in a wide temperature range on an HT-1000 friction and wear testing machine. The friction and wear test conditions are as follows: ball-on-disk contact rotation friction mode, the friction pair is an Al2O3 (Φ6 mm) ball, the test load is 5 N, the rotation radius is 5 mm, the speed is 0.5 m / s, and the time is 30 min; the ambient temperatures are 25 °C, 200 °C, 400 °C, 600 °C, and 800 °C in the atmospheric environment respectively; the wear rate of the coating is obtained by measuring the wear volume with a non-contact optical three-dimensional surface profiler and calculating. The friction and wear test results of the coating in a wide temperature range are shown in Table 1.

[0038] Table 1 Test results As can be seen from Table 1, the NiCr-Cr3C2-BaF2 / CaF2 coating on the titanium alloy surface has a low friction coefficient and a small wear rate in the wide temperature range of 25 to 800 °C, and the tribological properties of the coating improve significantly with the gradual increase of temperature.

[0039] Example 2 A method for preparing a wide-temperature-range wear-resistant self-lubricating coating on the surface of a titanium alloy, comprising the following steps: ⑴ Prepare spherical or near-spherical mixed lubricant spraying powder: ① Weigh 100 g of BaF2 / CaF2 eutectic powder with a powder particle size of 100 - 900 nm, 20 g of MoS2 powder with a particle size of 400 - 1000 nm, and 80 g of Ni powder with a particle size of 300 - 800 nm using an electronic balance, and mix them evenly to obtain a mixed powder.

[0040] ② Add the mixed powder to 200 mL of a polyvinyl alcohol aqueous solution with a mass concentration of 5.0 g / L and stir to form a homogeneous slurry; the slurry is ball-milled using a low-energy ball mill, and after the ball-milled slurry is spray-dried and granulated, spherical or near-spherical mixed powder composed of BaF2 / CaF2 eutectic, MoS2, and Ni powder is obtained.

[0041] Among them: The conditions for spray drying and granulation refer to that the flow rate of the slurry is controlled at 20.0 - 22.0 mL / min, the inlet air temperature of the spray dryer equipment is set at 220 °C, the outlet temperature is set at 105 °C, and the rotation frequency of the atomizer turntable is 35 Hz; after the granulation is completed, the powder is placed in a vacuum drying oven and dried at 90 °C for 5 h.

[0042] ③ The spherical or near-spherical mixed powder is sintered in an Ar atmosphere environment, the sintering target temperature is 800 °C, the heating rate is 10 °C / min, and the holding time is 1.5 h. After sintering and screening, spherical or near-spherical mixed lubricant spraying powder with a particle size of 13 - 59 μm and composed of sub-micron scale BaF2 / CaF2 eutectic, MoS2, and Ni powder is obtained.

[0043] ⑵ Prepare the spraying powder raw material: Accurately weigh 10 g of spherical or near-spherical mixed lubricant spraying powder, 10 g of atomized Ag powder, and 80 g of NiCr-Cr3C2 powder, mix them evenly, and dry them at 85 °C for 1 h to obtain the spraying powder raw material.

[0044] ⑶ Use the detonation spraying technology to prepare the NiCr-Cr3C2-BaF2 / CaF2-MoS2-Ag coating on the surface of the titanium alloy: On the surface of the Ti6Al4V titanium alloy substrate that has been pre-polished with sandpaper, sandblasted, ultrasonically cleaned with anhydrous ethanol and acetone, and dried, first spray the air twice with a spray gun to achieve preheating and cleaning of the titanium alloy substrate surface; then deposit the NiCrAlY alloy powder with a particle size of 22 - 63 μm on the Ti6Al4V titanium alloy substrate surface to form a bond coat, continuously spray 2 layers, and the deposition thickness is about 65 μm; finally, deposit the wear-resistant self-lubricating layer on the surface of the bond coat with the sprayed powder raw material, continuously repeat spraying 25 layers, and the deposition thickness is about 500 μm.

[0045] The detonation spraying conditions refer to that the fuel gas is a mixed gas of acetylene and propane, the oxygen is the combustion-supporting gas, the nitrogen is the auxiliary gas, the gas filling volume of the gun is 55%, the oxygen-fuel ratio is 1.17:1, the spraying frequency is 5 Hz, the spraying distance is 150 mm, the spraying angle is 90°, and the moving speed of the spray gun is 60 mm / s.

[0046] The prepared NiCr-Cr3C2-BaF2 / CaF2-MoS2-Ag coating has a dense structure, good interfacial bonding between the lubricating phase and the coating matrix and uniform distribution. The microscopic structure characterization results of the coating cross-section are shown in Figure 1 .

[0047] Conduct a wide-temperature range friction and wear test on this coating on an HT-1000 friction and wear testing machine. The test method is the same as that in Example 1, and the test results are shown in Table 2 and Figure 2 .

[0048] Table 2 Test Results From Table 2 and Figure 2 it can be seen that the NiCr-Cr3C2-BaF2 / CaF2-MoS2-Ag coating has excellent tribological properties in the wide temperature range of 25 - 800 °C. The friction coefficient and wear rate of the coating in the wide temperature range are as low as 0.16 - 0.36 and 10 - 6 mm 3 / N·m order of magnitude.

[0049] Example 3 A preparation method of a wide-temperature range wear-resistant self-lubricating coating on a titanium alloy surface, comprising the following steps: ⑴ Prepare spherical or quasi-spherical mixed lubricant spraying powder in the same way as in Example 2.

[0050] ⑵ Prepare the spraying powder raw material: Accurately weigh 12.5 g of spherical or quasi-spherical mixed lubricant spraying powder, 12.5 g of atomized Ag powder and 75 g of NiCr-Cr3C2 powder, mix them evenly and dry at 85 °C for 1 h to obtain the spraying powder raw material.

[0051] ⑶ Prepare the NiCr-Cr3C2-BaF2 / CaF2-MoS2-Ag coating on the titanium alloy surface by using the detonation spraying technique: On the surface of the Ti6Al4V titanium alloy substrate that has been pre-treated by sandpaper grinding, sandblasting, ultrasonic cleaning with anhydrous ethanol and acetone, and drying, first spray the gun empty 3 times to achieve preheating and cleaning of the titanium alloy substrate surface; then deposit the NiCrAlY alloy powder with a particle size of 22 - 63 μm on the Ti6Al4V titanium alloy substrate surface for the bonding layer, spray 3 layers continuously, and the deposition thickness is about 100 μm; finally, deposit the wear-resistant self-lubricating layer on the surface of the bonding layer with the spraying powder raw material, spray 25 layers continuously and repeatedly, and the deposition thickness is 550 μm.

[0052] The detonation spraying conditions refer to that the fuel gas is a mixed gas of acetylene and propane, the oxygen is the combustion-supporting gas, the nitrogen is the auxiliary gas, the gas filling volume of the gun is 55%, the oxygen-fuel ratio is 1.17:1, the spraying frequency is 5 Hz, the spraying distance is 145 mm, the spraying angle is 90°, and the moving speed of the gun is 60 mm / s.

[0053] The prepared NiCr-Cr3C2-BaF2 / CaF2-MoS2-Ag coating has a dense structure, and the lubricating phase has a good interfacial bonding with the coating matrix and is evenly distributed.

[0054] Conduct the wide-temperature-range friction and wear test on this coating on the HT-1000 friction and wear testing machine, and the test method is the same as that in Example 1. The test results are shown in Table 3.

[0055] Table 3 Test Results As can be seen from Table 3, the NiCr-Cr3C2-BaF2 / CaF2-MoS2-Ag coating has good tribological properties in the wide-temperature range of 25 - 800 °C, and it shows the lowest friction coefficient and the smallest wear rate at 800 °C.

Claims

1. A wide temperature range wear-resistant self-lubricating coating on the surface of titanium alloy, characterized by: The coating consists of a NiCrAlY bonding layer and a NiCr-Cr3C2-based wide temperature range wear-resistant self-lubricating layer with Ag, submicron-scale BaF2 / CaF2 eutectic and MoS2 as lubricating phases, or consists of a NiCrAlY bonding layer and a NiCr-Cr3C2-based wide temperature range wear-resistant self-lubricating layer with submicron-scale BaF2 / CaF2 eutectic as lubricating phases.

2. The method for preparing a wide temperature range wear-resistant self-lubricating coating on a titanium alloy surface according to claim 1, comprising the following steps: ⑴ Preparation of spherical or quasi-spherical mixed lubricant spray powder: ① BaF2 / CaF2 eutectic powder with a particle size of 100-900 nm, MoS2 powder with a particle size of 400-1000 nm, and Ni powder with a particle size of 300-800 nm are weighed and mixed uniformly according to mass percentages of 40-50 wt.%, 0-10 wt.%, and 40-50 wt.%, respectively, to obtain a mixed powder; ② The mixed powder is added to the polyvinyl alcohol aqueous solution and stirred into a uniform slurry; the slurry is ball-milled by a low-energy ball mill and spray-dried to granulate to obtain a spherical or quasi-spherical mixed powder composed of submicron-scale BaF2 / CaF2 eutectic, MoS2 and Ni powder; ③ The spherical or quasi-spherical mixed powder is sintered and densified in an Ar atmosphere environment and then sieved to obtain a spherical or quasi-spherical mixed lubricant spray powder with a particle size of 13 to 59 μm composed of submicron-scale BaF2 / CaF2 eutectic, MoS2 and Ni powder; ⑵Prepare spray powder raw materials: By mass percentage, 10-12.5 wt.% of the spherical or quasi-spherical mixed lubricant spray powder, 0-12.5 wt.% of atomized Ag powder and the balance NiCr-Cr3C2 powder are mixed uniformly and then dried at a drying temperature of 75-85° C. for 1-2 h to obtain a spray powder raw material; ⑶Use explosion spraying technology to prepare wide temperature range wear-resistant self-lubricating coating: The surface of a Ti6Al4V titanium alloy substrate that has been previously sanded, sandblasted, ultrasonically cleaned with anhydrous ethanol and acetone, and dried is first sprayed 2 to 4 times with a spray gun, and a NiCrAlY alloy powder with a particle size of 22 to 63 μm is deposited on the surface of the Ti6Al4V titanium alloy substrate as a bonding layer, and 1 to 3 layers are sprayed continuously with a deposition thickness of 50 to 100 μm; finally, the sprayed powder raw material is deposited on the surface of the bonding layer as a wear-resistant self-lubricating layer, and the spraying is repeated for 20 to 25 layers, and the deposition thickness is controlled at 350 to 550 μm, so as to obtain a wide temperature range wear-resistant self-lubricating coating.

3. The method for preparing a wide temperature range wear-resistant self-lubricating coating on a titanium alloy surface according to claim 1, characterized in that: The mass concentration of the polyvinyl alcohol aqueous solution in step ② is 4.0-5.0 g / L.

4. The method for preparing a wide temperature range wear-resistant self-lubricating coating on a titanium alloy surface according to claim 1, characterized in that: The mass volume ratio of the mixed powder to the polyvinyl alcohol aqueous solution in step ② is 1 g: 1 mL.

5. The method for preparing a wide temperature range wear-resistant self-lubricating coating on a titanium alloy surface according to claim 1, characterized in that: The conditions for spray drying granulation in step ② are that the flow rate of the ball-milled slurry is controlled to be 18.0-22.0 mL / min, the inlet air temperature of the spray dryer is set to 220-230°C, the outlet temperature is 100-105°C, and the rotation frequency of the atomizer turntable is 35-40 Hz; after the granulation is completed, the powder is placed in a vacuum drying oven at 70-90°C and dried for 5-8 hours.

6. The method for preparing a wide temperature range wear-resistant self-lubricating coating on a titanium alloy surface according to claim 1, characterized in that: The sintering densification treatment conditions in step ③ are as follows: the sintering target temperature is 800-850°C, the heating rate is 10°C / min, and the holding time is 1-1.5 h.

7. The method for preparing a wide temperature range wear-resistant self-lubricating coating on a titanium alloy surface according to claim 1, characterized in that: The particle size of the atomized Ag powder in step (2) is 13-66 μm; the particle size of the NiCr-Cr3C2 powder is 8-62 μm, which is sintered by mixing 25wt.% 80Ni20Cr and 75wt.% Cr3C2.

8. The method for preparing a wide temperature range wear-resistant self-lubricating coating on a titanium alloy surface according to claim 1, characterized in that: The explosion spraying conditions in step (3) refer to that the fuel gas is a mixture of acetylene and propane, oxygen is the combustion-supporting gas, nitrogen is the auxiliary gas, the spray equipment barrel is a telescopic barrel, the gas filling gun volume is 55%, the oxygen-fuel ratio is 1.17:1, the spraying frequency is 5 Hz, the spraying distance is 145~155 mm, the spraying angle is 90°, and the spray gun moving speed is 60 mm / s.

Images