Strontium titanate-high-entropy alloy high-temperature self-lubricating wear-resistant coating and preparation method thereof

Abstract

The invention relates to a strontium titanate-high-entropy alloy high-temperature self-lubricating wear-resistant coating. The coating is prepared from the following components in percentage by mass: 5 to 35 percent of SrTiO3 ceramic phase and 65 to 95 percent of Ni < 20 > Co < 20 > Cr < 20 > Fe < 20 > Mn < 20 > high-entropy alloy phase. Meanwhile, the invention further discloses a preparation method of the coating. According to the invention, SrTiO3 is introduced into a Ni20Co20Cr20Fe20Mn20 high-entropy alloy matrix by adopting an explosion spraying process to form a functional composite coating, and the prepared coating shows excellent wear resistance and tribological performance in an extreme environment of 800-1000 DEG C; the method has important application prospects in the surface protection aspect of high-temperature parts such as turbine blades, transmission / motion bearings and combustion chambers in the fields of spaceflight, automobiles and energy.

Description

Technical Field

[0001] This invention relates to the field of high-temperature lubricating coating materials and surface engineering technology, and in particular to a high-temperature self-lubricating and wear-resistant coating of strontium titanate-high entropy alloy and its preparation method. Background Technology

[0002] In existing technologies, metal-based self-lubricating coatings (such as the PS series coatings developed by NASA) exhibit significant limitations in performance under high temperature, high load, and high speed conditions. The main problem lies in the dimensional instability caused by high-temperature oxidation and the thermal softening effect of the metal substrate, leading to frequent adhesive wear. This makes it difficult to meet the stringent requirements for thermal stability, wear resistance, and interface integrity imposed on coating materials in applications such as hypersonic vehicles and high-thrust propulsion systems. To address these issues, high-entropy alloys (such as Ni...) are being developed... 20 Co 20 Cr 20 Fe 20 Mn 20 High-entropy alloys have attracted widespread attention due to their excellent thermal stability and mechanical properties. However, although this alloy system possesses excellent thermal stability and mechanical properties, its tribological properties significantly decrease under extreme conditions above 800 °C, and it also suffers from grain boundary weakening, which limits its application in high-temperature self-lubricating fields. Furthermore, single high-entropy alloy materials lack effective lubrication mechanisms in high-temperature environments, making it difficult to meet lubrication requirements under extreme operating conditions.

[0003] While traditional high-temperature solid lubricants (such as silver, fluorides, and molybdates) can improve the tribological properties of materials to some extent, they still present numerous problems in practical applications. First, these solid lubricants are prone to lubrication failure under high-temperature conditions, such as losing their lubricating function due to high-temperature volatilization or decomposition. Second, the significant difference in thermal expansion coefficients between them and the metal matrix often leads to substantial interfacial stress concentration during temperature cycles, resulting in interfacial cracking. Furthermore, the lubricating glaze layer formed by traditional lubricants at high temperatures is often unstable and fails to provide durable lubrication protection. These problems severely limit the practical application of traditional solid lubricants in high-temperature engineering. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a high-performance strontium titanate-high entropy alloy high-temperature self-lubricating wear-resistant coating.

[0005] Another technical problem to be solved by the present invention is to provide a method for preparing the high-temperature self-lubricating and wear-resistant coating of the strontium titanate-high entropy alloy.

[0006] To address the aforementioned problems, the present invention provides a high-temperature self-lubricating and wear-resistant coating for a strontium titanate-high-entropy alloy, characterized in that: the coating comprises 5-35 wt.% SrTiO3 ceramic phase and 65-95 wt.% Ni. 20 Co 20 Cr 20 Fe 20 Mn 20 It consists of a high-entropy alloy phase.

[0007] The preparation method of the strontium titanate-high entropy alloy high-temperature self-lubricating wear-resistant coating as described above includes the following steps: (1) Weigh Ni according to the ratio 20 Co 20 Cr 20 Fe 20 Mn 20 High-entropy alloy powder and SrTiO3 ceramic powder are mixed evenly in a low-energy ball mill to obtain the pre-coated powder. (2) The NiCrAlY adhesive layer is prepared on the surface of the treated metal substrate by explosive spraying process. (3) The pre-coated powder is used to prepare Ni on the surface of the NiCrAlY adhesive layer by explosive spraying process. 20 Co 20 Cr 20 Fe 20 Mn 20 -SrTiO3 high-temperature self-lubricating wear-resistant coating.

[0008] In step (1), Ni 20 Co 20 Cr 20 Fe 20 Mn 20 The high-entropy alloy powder is spherical with a particle size of 17~67 μm.

[0009] In step (1), the SrTiO3 powder is spherical with a particle size of 12~42 μm.

[0010] In step (1), the ball milling conditions of the low-energy ball mill are a ball-to-material ratio of 1:1.5 to 1:2.5 and a time of 2.5 to 4 hours.

[0011] In step (2), the NiCrAlY powder is a regular spherical powder with a particle size of 9~60 μm.

[0012] The metal substrate processed in step (2) refers to the metal substrate that has been polished by sanding with 100, 200, 600, 800 and 1200 grit sandpaper in sequence, then ultrasonically cleaned and dried, and finally shot-blasted, ultrasonically cleaned and dried using a high-pressure sandblasting machine.

[0013] In step (2), the thickness of the NiCrAlY adhesive layer is 65~90 μm.

[0014] The conditions for the explosive spraying process in steps (2) and (3) are as follows: the oxygen-to-carbon ratio of the explosive gas mixture is 1:1.171 to 1:212; the fuel gas components are acetylene and propane; the gas filling rate is 45% to 67%; pulse powder feeding and ignition are used; the spraying frequency is 2.2 to 4.5 Hz; the powder feeding rate is 3.5 g / shot; the spraying distance is 170 to 280 mm; and nitrogen is used as the powder carrier gas and protective gas.

[0015] In step (3), the thickness of the high-temperature self-lubricating wear-resistant coating is 270~331 μm.

[0016] Compared with the prior art, the present invention has the following advantages: 1. This invention uses Ni 20 Co 20 Cr 20 Fe 20 Mn 20 Using a high-entropy alloy as the matrix gives the coating considerable high-temperature load-bearing capacity; selecting SrTiO3 with an ABO3-type perovskite structure as the high-temperature lubricating phase can effectively improve the friction and wear performance in the high-temperature domain.

[0017] SrTiO3 is an ideal high-temperature lubrication reinforcing phase due to its excellent material properties. Firstly, SrTiO3 has a high melting point, maintaining good thermal stability at high temperatures. Secondly, its moderate hardness allows it to effectively disperse external loads during lubrication. Furthermore, SrTiO3 has a similar coefficient of thermal expansion to the metal matrix, significantly reducing interfacial stress concentration and improving the overall stability of the coating. More importantly, under high-temperature conditions, strontium titanate can undergo plastic deformation through dislocation slip and grain boundary slip, participating in and promoting the formation of a stable and continuous lubricating enamel layer, thereby effectively improving the high-temperature tribological properties and interfacial integrity of the coating.

[0018] 2. This invention employs an explosive spraying process to introduce SrTiO3 into Ni. 20 Co 20 Cr 20 Fe 20 Mn 20 A high-entropy alloy matrix is ​​used to form a functional composite coating. The prepared coating exhibits excellent wear resistance and tribological properties in extreme environments of 800~1000 ℃, and has important application prospects in the surface protection of high-temperature components such as turbine blades, transmission / motion bearings and combustion chambers in the aerospace, automotive and energy fields.

[0019] 3. The equipment of this invention is simple and easy to operate, the process is controllable, the cost is low, and it can be used for mass production. Attached Figure Description

[0020] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0021] Figure 1 The XRD diffraction patterns are those of the coatings prepared in the comparative examples and Examples 1-2 of this invention.

[0022] Figure 2 The 90 wt.% Ni prepared in Example 2 of this invention 20 Co 20 Cr 20 Fe 20 Mn 20 Microstructure and EDS elemental distribution diagram of the surface of a -10 wt. % SrTiO3 high-entropy alloy high-temperature self-lubricating wear-resistant composite coating.

[0023] Figure 3 The 90 wt.% Ni prepared in Example 2 of this invention 20 Co 20 Cr 20 Fe 20 Mn 20 Microstructure and elemental distribution diagram of a -10 wt. % SrTiO3 high-entropy alloy high-temperature self-lubricating wear-resistant composite coating.

[0024] Figure 4 The wear rate is shown for the coatings prepared in the comparative examples and Examples 1-2 of this invention.

[0025] Figure 5 The coefficient of friction is the coefficient of friction of the coatings prepared in the comparative examples and Examples 1-2 of this invention. Detailed Implementation

[0026] A high-temperature self-lubricating and wear-resistant coating of strontium titanate-high entropy alloy, comprising 5-35 wt.% SrTiO3 ceramic phase and 65-95 wt.% Ni. 20 Co 20 Cr 20 Fe 20 Mn 20 It consists of a high-entropy alloy phase.

[0027] Its preparation method includes the following steps: (1) Weigh Ni according to the ratio 20 Co 20 Cr 20 Fe 20 Mn 20High-entropy alloy powder and SrTiO3 ceramic powder are mixed evenly in a low-energy ball mill at a ball-to-material ratio of 1:1.5 to 1:2.5 for 2.5 to 4 hours to obtain the pre-coated powder.

[0028] Ni 20 Co 20 Cr 20 Fe 20 Mn 20 The high-entropy alloy powder is spherical with a particle size of 17–67 μm. The SrTiO3 powder is spherical with a particle size of 12–42 μm.

[0029] (2) The NiCrAlY bonding layer powder is placed into the powder feeder, and an explosive spraying process is used to prepare a NiCrAlY bonding layer with a thickness of 65~90 μm on the surface of the treated metal substrate. The conditions for the explosive spraying process are as follows: the oxygen-to-carbon ratio of the explosive gas mixture is 1:1.171~1:212, the fuel gas components are acetylene and propane, the gas filling rate is 45%~67%, pulse powder feeding and ignition are used, the spraying frequency is 2.2~4.5Hz, the powder feeding rate is 3.5 g / shot, the spraying distance is 170~280 mm, and nitrogen is used as the powder carrier gas and protective gas.

[0030] NiCrAlY powder is a regular spherical powder with a particle size of 9~60 μm.

[0031] The treated metal substrate refers to a metal substrate that has been successively polished with 100, 200, 600, 800, and 1200 grit sandpaper, then ultrasonically cleaned and dried. Finally, the surface of the metal substrate is shot-blasted using a high-pressure sandblasting machine, followed by ultrasonic cleaning and drying. The metal substrate material can be high-temperature resistant stainless steel, copper alloy, titanium alloy, and nickel-based high-temperature alloy, etc.

[0032] (3) The pre-coated powder is placed into the powder feeder, and a NiCrAlY adhesive layer with a thickness of 270~331 μm is prepared on the surface of the NiCrAlY adhesive layer using an explosive spraying process. 20 Co 20 Cr 20 Fe 20 Mn 20 -SrTiO3 high-temperature self-lubricating wear-resistant coating. The conditions for the explosive spraying process are the same as in step (2).

[0033] Comparative Example Weigh 100g Ni 20 Co 20 Cr 20 Fe 20 Mn 20High-entropy alloy powder was placed in a ball mill jar and mixed evenly in a low-energy ball mill at a ball-to-powder ratio of 1:1.5 for 2.5 hours to obtain pre-coated powder. A 316L metal substrate was polished with 100, 200, 600, 800, and 1200 grit sandpaper, followed by ultrasonic cleaning and drying. Then, the surface of the metal substrate was shot-peened using a high-pressure sandblasting machine, ultrasonically cleaned, and dried for later use. NiCrAlY powder was loaded into a powder feeder, and an explosive spraying process was used to prepare a NiCrAlY bonding layer on the surface of the metal substrate. Subsequently, the pre-coated powder was placed into the powder feeder, and an explosive spraying process was used to prepare a wear-resistant coating on the surface of the NiCrAlY bonding layer. The explosive spraying process is as follows: a mixture of explosive gas (composed of acetylene and propane) and oxygen with an oxygen-to-carbon ratio of 1:1.212 is used; the gas filling rate is 45%; the spraying frequency is 4.5 Hz; the powder feed rate is 3.5 g / shot; the spraying distance is 280 mm; and nitrogen is used as both the powder carrier gas and the protective gas. After spraying, the coating surface is allowed to cool naturally, yielding Ni. 20 Co 20 Cr 20 Fe 20 Mn 20 High-entropy alloy high-temperature self-lubricating wear-resistant composite coating.

[0034] The phase composition and chemical structure of the obtained coating were characterized by X-ray diffraction (XRD), and the results are as follows: Figure 1 As shown in the figure. It can be seen from the figure that Ni 20 Co 20 Cr 20 Fe 20 Mn 20 The high-entropy alloy high-temperature self-lubricating wear-resistant composite coating is mainly composed of a high-entropy alloy FCC matrix phase.

[0035] The obtained coating was subjected to high-temperature tribological performance testing using a GF-I type high-temperature friction and wear testing machine. The abrasive was a 6 mm diameter Si3N4 ceramic ball. The test conditions were set as follows: temperature 800 ℃ and 1000 ℃, sliding speed 0.1 m / s, load 10 N, and test duration 30 min. The coefficient of friction and wear rate are shown in Table 1. Figures 4-5 As shown.

[0036] Table 1 Example 1 Weigh out 95 g of Ni 20 Co 20 Cr 20 Fe 20 Mn 20High-entropy alloy and 5 g of SrTiO3 ceramic powder were placed in a ball mill jar and mixed evenly in a low-energy ball mill at a ball-to-powder ratio of 1:2 for 3.2 h to obtain pre-coated powder. A 316L metal substrate was polished with 100, 200, 600, 800, and 1200 grit sandpaper, then ultrasonically cleaned and dried. Following this, the surface of the metal substrate was shot-peened using a high-pressure sandblasting machine, and then ultrasonically cleaned and dried for later use. NiCrAlY powder was loaded into a powder feeder and an explosive spraying process was used to form a NiCrAlY bonding layer on the surface of the metal substrate. The pre-coated powder was then placed into a powder feeder and an explosive spraying process was used to prepare NiCrAlY bonding layer on the surface of the NiCrAlY bonding layer. 20 Co 20 Cr 20 Fe 20 Mn 20 -SrTiO3 high-entropy alloy high-temperature self-lubricating wear-resistant composite coating. The explosive spraying process is as follows: a mixture of explosive gas (composed of acetylene and propane) and oxygen with an oxygen-to-carbon ratio of 1:1.171, an air filling rate of 56%, a spraying frequency of 3.4 Hz, a powder feed rate of 3.5 g / shot, a spraying distance of 220 mm, and nitrogen as the powder carrier gas and protective gas. After spraying, the coating surface is allowed to cool naturally, yielding Ni... 20 Co 20 Cr 20 Fe 20 Mn 20 -5 wt. % SrTiO3 high-entropy alloy high-temperature self-lubricating wear-resistant composite coating.

[0037] The phase composition and chemical structure of the obtained coating were characterized by X-ray diffraction (XRD), and the results are as follows: Figure 1 As shown in the figure. It can be seen from the figure that Ni 20 Co 20 Cr 20 Fe 20 Mn 20 The -5 wt.% SrTiO3 high-entropy alloy high-temperature self-lubricating wear-resistant composite coating is mainly composed of a high-entropy alloy FCC matrix phase and a SrTiO3 lubricating phase.

[0038] The obtained coating was subjected to high-temperature tribological performance testing using a GF-I type high-temperature friction and wear testing machine. The testing method was the same as that for the comparative example. The coefficient of friction and wear rate are shown in Table 2. Figures 4-5 As shown.

[0039] Table 2 Example 2 Weigh 90 g Ni 20 Co 20 Cr 20Fe 20 Mn 20 High-entropy alloy and 10 g of SrTiO3 ceramic powder were placed in a ball mill jar and mixed evenly in a low-energy ball mill at a ball-to-powder ratio of 1:2.5 for 4 hours to obtain pre-coated powder. A 316L metal substrate was polished with 100, 200, 600, 800, and 1200 grit sandpaper, followed by ultrasonic cleaning and drying. Then, the surface of the metal substrate was shot-blasted using a high-pressure sandblasting machine, and ultrasonically cleaned and dried again for later use. NiCrAlY powder was loaded into a powder feeder and an explosive spraying process was used to form a NiCrAlY bonding layer on the surface of the metal substrate. The pre-coated powder was then placed into a powder feeder and an explosive spraying process was used to prepare NiCrAlY bonding layer on the surface of the NiCrAlY bonding layer. 20 Co 20 Cr 20 Fe 20 Mn 20 -SrTiO3 high-entropy alloy high-temperature self-lubricating wear-resistant composite coating. The explosive spraying process is as follows: a mixture of explosive gas (composed of acetylene and propane) and oxygen with an oxygen-to-carbon ratio of 1:1.189, an air filling rate of 56%, a spraying frequency of 3.4 Hz, a powder feed rate of 3.5 g / shot, a spraying distance of 170 mm, and nitrogen as the powder carrier gas and protective gas. After spraying, the coating surface is allowed to cool naturally, yielding Ni... 20 Co 20 Cr 20 Fe 20 Mn 20 -10 wt. % SrTiO3 high-entropy alloy high-temperature self-lubricating wear-resistant composite coating.

[0040] The phase composition and chemical structure of the obtained coating were characterized by X-ray diffraction (XRD), and the results are as follows: Figure 1 As shown in the figure. It can be seen from the figure that Ni 20 Co 20 Cr 20 Fe 20 Mn 20 The -10 wt.% SrTiO3 high-entropy alloy high-temperature self-lubricating wear-resistant composite coating is mainly composed of a high-entropy alloy FCC matrix phase and a SrTiO3 lubricating phase.

[0041] The surface and cross-sectional morphology, elemental distribution, and compositional characteristics of the obtained coating were observed and analyzed using a scanning electron microscope (SEM) and its associated energy dispersive spectroscopy (EDS). The results are as follows: Figures 2-3 As shown in the figure, the SrTiO3 lubricating phase particles are uniformly distributed in Ni. 20 Co 20 Cr 20 Fe 20 Mn20 The middle layer of a high-entropy alloy.

[0042] The obtained coating was subjected to high-temperature tribological performance testing using a GF-I type high-temperature friction and wear testing machine. The testing method was the same as that for the comparative example. The coefficient of friction and wear rate are shown in Table 3. Figures 4-5 As shown.

[0043] Table 3 According to Tables 1-3, Figures 4-5 It can be seen that the SrTiO3 lubricating phase is present in Ni 20 Co 20 Cr 20 Fe 20 Mn 20 The introduction of high-entropy alloy coatings significantly reduced the tribological coefficient and wear rate of high-entropy alloy high-temperature self-lubricating wear-resistant composite coatings at 800~1000 ℃.

Claims

1. A high-temperature self-lubricating and wear-resistant coating of strontium titanate-high entropy alloy, characterized in that: The coating consists of 5–35 wt.% SrTiO3 ceramic phase and 65–95 wt.% Ni. 20 Co 20 Cr 20 Fe 20 Mn 20 It consists of a high-entropy alloy phase.

2. The method for preparing a high-temperature self-lubricating wear-resistant coating of strontium titanate-high entropy alloy as described in claim 1, comprising the following steps: (1) Weigh Ni according to the ratio 20 Co 20 Cr 20 Fe 20 Mn 20 High-entropy alloy powder and SrTiO3 ceramic powder are mixed evenly in a low-energy ball mill to obtain the pre-coated powder. (2) The NiCrAlY adhesive layer is prepared on the surface of the treated metal substrate by explosive spraying process. (3) The pre-coated powder is used to prepare Ni on the surface of the NiCrAlY adhesive layer by explosive spraying process. 20 Co 20 Cr 20 Fe 20 Mn 20 -SrTiO3 high-temperature self-lubricating wear-resistant coating.

3. The method for preparing a high-temperature self-lubricating wear-resistant coating of strontium titanate-high entropy alloy as described in claim 2, characterized in that: In step (1), Ni 20 Co 20 Cr 20 Fe 20 Mn 20 The high-entropy alloy powder is spherical with a particle size of 17~67 μm.

4. The method for preparing a high-temperature self-lubricating wear-resistant coating of strontium titanate-high entropy alloy as described in claim 2, characterized in that: In step (1), the SrTiO3 powder is spherical with a particle size of 12~42 μm.

5. The method for preparing a high-temperature self-lubricating wear-resistant coating of strontium titanate-high entropy alloy as described in claim 2, characterized in that: In step (1), the ball milling conditions of the low-energy ball mill are a ball-to-material ratio of 1:1.5 to 1:2.5 and a time of 2.5 to 4 hours.

6. The method for preparing a high-temperature self-lubricating wear-resistant coating of strontium titanate-high entropy alloy as described in claim 2, characterized in that: In step (2), the NiCrAlY powder is a regular spherical powder with a particle size of 9~60 μm.

7. The method for preparing a high-temperature self-lubricating wear-resistant coating of strontium titanate-high entropy alloy as described in claim 2, characterized in that: The metal substrate processed in step (2) refers to the metal substrate that has been polished by sanding with 100, 200, 600, 800 and 1200 grit sandpaper in sequence, then ultrasonically cleaned and dried, and finally shot-blasted, ultrasonically cleaned and dried using a high-pressure sandblasting machine.

8. The method for preparing a high-temperature self-lubricating wear-resistant coating of strontium titanate-high entropy alloy as described in claim 2, characterized in that: In step (2), the thickness of the NiCrAlY adhesive layer is 65~90 μm.

9. The method for preparing a high-temperature self-lubricating wear-resistant coating of strontium titanate-high entropy alloy as described in claim 2, characterized in that: The conditions for the explosive spraying process in steps (2) and (3) are as follows: the oxygen-to-carbon ratio of the explosive gas mixture is 1:1.171 to 1:212; the fuel gas components are acetylene and propane; the gas filling rate is 45% to 67%; pulse powder feeding and ignition are used; the spraying frequency is 2.2 to 4.5 Hz; the powder feeding rate is 3.5 g / shot; the spraying distance is 170 to 280 mm; and nitrogen is used as the powder carrier gas and protective gas.

10. The method for preparing a high-temperature self-lubricating wear-resistant coating of strontium titanate-high entropy alloy as described in claim 2, characterized in that: In step (3), the thickness of the high-temperature self-lubricating wear-resistant coating is 270~331 μm.

Images