Self-lubricating alloy capable of replacing oil lubrication in seawater environment and preparation method of self-lubricating alloy

Abstract

The invention belongs to the field of corrosion and self-lubrication, and particularly relates to a self-lubricating alloy capable of replacing oil lubrication in a seawater environment and a preparation method of the self-lubricating alloy. The alloy is prepared by mixing corrosion-resistant nickel, cobalt or iron-based alloy powder serving as base powder with niobium powder and molybdenum powder through spark plasma sintering and has a multi-stage grain size microstructure, and the niobium powder and the molybdenum powder can be replaced by tantalum powder and tungsten powder respectively. Through component and structure regulation and control, a corrosion-resistant self-lubricating friction product is formed on the surface of the alloy in situ when the alloy is rubbed in a seawater environment, the friction coefficient is as low as 0.1 or below, the bottleneck problem that an alloy material in the marine environment cannot be lubricated by oil is solved, and the alloy can be applied to production of motion and transmission parts such as underwater sealing and bearings in the marine environment.

Description

Technical Field

[0001] The present invention belongs to the fields of corrosion and self-lubrication, and particularly relates to a self-lubricating alloy that can replace oil lubrication in a seawater environment and a preparation method thereof. Background Art

[0002] Wear and corrosion are two processes of surface damage caused by the gradual loss of materials due to mechanical and electrochemical processes respectively. When these two degradation processes occur simultaneously, it is called tribocorrosion. The synergistic effect between wear and corrosion may lead to significant material loss, seriously affecting the durability and safety of the used components. To reduce the corrosion and wear of materials, lubricating oils and greases are usually applied to the friction surfaces. However, in a severe marine tribocorrosion environment, it is difficult to ensure the use performance and safety of lubricating oils and greases. Based on this situation, people have realized that the production of self-lubricating materials is the key to solving the problem.

[0003] Generally, researchers can obtain a relatively low coefficient of friction by preparing composite materials through the addition of common solid lubricating phases (such as graphite and WS2). For example, Chinese Patent CN202211038539.7 discloses a graphite-steel-based self-lubricating and wear-resistant composite material, which prepares nearly spherical nickel-coated graphite particles by a chemical coating method. During sintering, the nickel coating hinders the reaction of the dispersed graphite dissolved in the molten steel, enabling the steel matrix to form a porous structure with nearly spherical graphite as inlays, obtaining excellent tribological and mechanical properties; CN202211315513.2 discloses a self-lubricating nickel-based composite material induced by laser or arc-induced diamond graphitization. By adding diamond crushed powder with incomplete crystal form, allotropic transformation occurs during the laser or arc cladding process, generating a self-lubricating graphite phase and thus having good anti-wear performance; CN202211131273.0 discloses a surface in-situ configured metal-based high-temperature self-lubricating composite material, that is, using WS2 as the lubricating phase, and a heterogeneous core-shell structure nickel-based composite material with an uneven texture formed by surface oxidation products storing wear debris and promoting the formation of a wear-resistant enamel layer during high-temperature friction is prepared by a spark plasma sintering technique. However, due to the poor bonding between the lubricating phase and the metal interface, the pores or cracks therein will become channels for electrolytes to diffuse into the matrix, promoting the accelerated corrosion of the material in the corrosive medium, resulting in limited application of the material in a seawater environment. Therefore, the design of self-lubricating materials with good tribological properties in a marine environment has gradually attracted the attention of researchers.

[0004] In recent studies, molybdenum has been tested as an alloying element to improve tribological properties by forming self-lubricating oxides. Chinese Patent CN201910347989.6 discloses a method for preparing a self-lubricating coating containing molybdenum dioxide, that is, using a composite material sintered from nickel powder and molybdenum disulfide powder as an electrode, and adopting an electro-discharge deposition technique to deposit a self-lubricating coating containing molybdenum dioxide on the surface of a steel substrate. It has been found that during the friction process, the flaky crystals of molybdenum oxide can cause interlayer separation, thereby reducing the frictional resistance and material loss. Therefore, considering the method of element addition, as the element source for tribochemical oxidation reaction, and using the ideal layered oxides and oxide derivative phases generated on the surface for lubrication may be an effective way to achieve self-lubrication in a seawater environment.

[0005] Therefore, according to the requirements of industrial development for the corrosion resistance and self-lubricating properties of materials, it is urgent to develop a self-lubricating material with excellent tribological properties in a seawater environment, so as to prepare key transmission components such as bushings and bearings that can operate in a seawater environment. Summary of the Invention

[0006] The purpose of the present invention is to provide a self-lubricating alloy that can replace oil lubrication in a seawater environment and its preparation method, which solves the bottleneck problem that alloy materials in a marine environment cannot be oil-lubricated, and at the same time avoids the disadvantages of low strength of self-lubricating materials, failure induced by corrosion wear, and poor lubrication effect, and can be applied to the production of moving and transmission components such as underwater seals and bearings in a marine environment.

[0007] To achieve the purpose of this invention, the following technical solutions are adopted: A self-lubricating alloy that can replace oil lubrication in a seawater environment, comprising raw materials in the following mass percentages: 70 - 80% of corrosion-resistant nickel-based alloy powder, cobalt-based alloy powder or iron-based alloy powder; its particle size is 20 - 50 μm; 10 - 20% of niobium powder, its particle size is 10 - 20 μm; 10 - 20% of molybdenum powder, its particle size is 2 - 5 μm The alloy uses corrosion-resistant nickel-based alloy powder, cobalt-based alloy powder or iron-based alloy powder as the base powder, is mixed with niobium powder and molybdenum powder, and is prepared by spark plasma sintering. It has a multi-level grain size microstructure, and its performance indicators are: compressive strength ≥ 1600 MPa, compressive deformation rate ≥ 32%; seawater reciprocating friction coefficient ≤ 0.10, wear rate ≤ 2.0×10 -5 mm 3 / Nm.

[0008] Preferably, for the above-mentioned self-lubricating alloy that can replace oil lubrication in a seawater environment, the base powder is selected from at least one of the following: Nickel-based alloy powders: NiCr, FGH97, In738 superalloy powders; Cobalt-based alloy powders: CoCr, CoCrW, GH605 superalloy powders; Iron-based alloy powders; FeCr, 316 stainless steel, 304 stainless steel or iron-based superalloy powders.

[0009] Preferably, for the self-lubricating alloy that can replace oil lubrication in a seawater environment mentioned above, niobium powder and molybdenum powder can be replaced by tantalum powder and tungsten powder respectively.

[0010] The preparation method of the self-lubricating alloy that can replace oil lubrication in a seawater environment mentioned above includes the following steps: (1) Powder mixing: Use a planetary ball mill to mix the original powders weighed according to the formula, with a rotation speed of 200 - 400 r / min, operating intermittently, stopping for 15 min every 30 - 60 min of operation, and the ball milling time is 8 h. Place the ball-milled powder in a drying oven to dry, and obtain powder A; (2) Die filling and cold pressing: First, evenly spray boron nitride in the graphite die for sintering, then line the inner wall of the graphite die with graphite paper, and then put powder A into the graphite die. Use a hydraulic press to pre-press the filled powder and hold for 60 - 120 s; use a universal testing machine to apply pressure and hold for 2 - 3 min and then unload; (3) Spark plasma sintering: Place the graphite die filled with powder into a sintering furnace with a vacuum degree less than 1×10 -2 atm, and heat it in two stages: First, heat it to 1050 - 1090 °C at a speed of 40 - 50 °C / min, and then heat it to 1100 - 1130 °C at a speed of 15 - 25 °C / min; keep it warm for 10 - 20 min and then slowly cool with the furnace, and the sintering pressure is 35 - 50 MPa.

[0011] Preferably, for the preparation method of the self-lubricating alloy that can replace oil lubrication in a seawater environment mentioned above, in step (1), the ball milling process uses a stainless steel ball milling tank and stainless steel balls, and the mass ratio of ball to material is 10:1. After loading the original powders, the ball milling tank will be placed in a planetary ball mill.

[0012] Preferably, for the preparation method of the self-lubricating alloy that can replace oil lubrication in a seawater environment mentioned above, in step (1), the drying temperature of the ball-milled powder in the drying oven is 45 °C, and the drying time is 2 h.

[0013] Preferably, in the preparation method of the self-lubricating alloy capable of replacing oil lubrication in the above-mentioned seawater environment, in step (2), the powder press pre-compresses the filled powder A at 20-30 MPa and holds the pressure for 60-120 s; the universal testing machine equipment is used to pressurize to 70-80 kN and hold for 2-3 min.

[0014] Preferably, in the preparation method of the self-lubricating alloy capable of replacing oil lubrication in the above-mentioned seawater environment, in step (3), the cooling rate of slow cooling in the furnace is 25 °C / min, and the furnace temperature is reduced to room temperature.

[0015] The design concept of the present invention is: After adding appropriate niobium and molybdenum to the corrosion-resistant nickel, cobalt or iron-based alloy powder, through mechanical alloying and spark plasma sintering, it has a multi-level grain size microstructure and makes the second phase evenly distributed. The strength of the material is improved through fine grain strengthening and solid solution strengthening. The presence of molybdenum can generate a lamellar molybdenum-rich hydrated oxide with a low shear modulus during friction and wear of the alloy, and the addition of niobium can increase the strength of the second-phase position, so that the lubricating phase generated at this position is preferentially subjected to the friction load, and with the lubrication and support of the second-phase region, the effect of reducing friction and wear is achieved. Among them, niobium powder and molybdenum powder can be replaced by tantalum powder and tungsten powder respectively. In addition, the fine grains at the second-phase position also provide a large number of grain boundaries, and elements such as niobium and molybdenum diffuse to the surface through the grain boundary diffusion channels, enabling the friction layer on the surface to be replenished in a timely manner. At the same time, this material does not contain brittle ceramic phases and low-strength and toughness lubricating phases such as soft metals and graphite, and retains the characteristics of high strength and high toughness of the metal matrix. To sum up, this material has excellent comprehensive properties such as corrosion resistance, high strength, high toughness, low friction coefficient and low wear rate.

[0016] The advantages and beneficial effects of the present invention are: (1) The material prepared by the present invention has a simple preparation process, and the raw materials required in the formula can be directly purchased in the market, and the preparation cost is low; (2) The material prepared by the present invention has relatively high hardness and compressive strength, and excellent mechanical properties; (3) The material prepared by the present invention has obtained excellent tribological properties in a seawater environment and can provide good wear-resistant and lubricating effects for a long time; (4) The material prepared by the present invention has good machinability, good electrical and thermal conductivity, and is easy to be processed into various shaped and sized parts. Description of the Drawings

[0017] Figure 1 : (a) is the microstructure of the self-lubricating alloy with good tribological and mechanical properties prepared by the spark plasma sintering process; (b) is the wear scar morphology of the alloy after reciprocating friction and wear testing in a seawater environment; Figure 2 : (a) shows the microstructure of the alloy without added molybdenum; (b) shows the wear scar morphology of the alloy without added molybdenum after reciprocating friction and wear tests in a seawater environment. Detailed implementation mode

[0018] The following embodiments are further detailed descriptions of the present invention. It should be understood that these modes are only used to illustrate the present invention and not to limit the scope of the present invention. Embodiment 1

[0019] In this embodiment, a self-lubricating alloy that can replace oil lubrication in a seawater environment includes raw materials with the following mass percentages: 70 wt% of NiCr alloy powder with a particle size of about 38 μm, 15 wt% of niobium powder with a particle size of about 20 μm, and 15 wt% of molybdenum powder with a particle size of about 4 μm. The composition of the NiCr powder is: Ni 80wt%, Cr 20wt%. Based on the micron-sized NiCr alloy powder as the matrix, it is mixed with niobium powder and molybdenum powder and prepared by spark plasma sintering. Its preparation method includes the following steps: (1) Powder mixing: Weigh the original powders according to the ratio. The ball milling process uses a stainless steel ball milling tank and stainless steel balls, and the ball-to-powder mass ratio is 10:1. After loading the original powders into the ball milling tank, use a planetary ball mill to mix the powders evenly at a rotation speed of 300 r / min, running intermittently, stopping for 15 min every 30 min of operation. After ball milling for 8 h, place the obtained powder in a drying oven for drying. The drying temperature is 45 °C, and the drying time is 2 h.

[0020] (2) Cold pressing in a mold: First, evenly spray boron nitride in the graphite mold for sintering, and then fill graphite paper on the inner wall of the graphite mold. Put the finally mixed and dried powder into the graphite mold and compact it with a hydraulic press. The hydraulic press pre-presses the graphite mold filled with the powder body at 20 MPa and holds the pressure for 60 s; use a universal testing machine to apply pressure up to 75 kN and hold for 2 min before unloading; (3) Spark plasma sintering: Put the graphite mold filled with the powder body into a sintering furnace with a vacuum degree of 5×10 -3 atm. Heat it up in two stages: First, raise the temperature to 1090 °C at a heating rate of 40 °C / min; then raise the temperature to 1100 °C at a heating rate of 20 °C / min. Finally, keep it at 1100 °C for 20 min and then cool it to room temperature with the furnace at a cooling rate of 25 °C / min. The sintering pressure is 40 MPa.

[0021] The density of the NiCr-15Nb-15Mo material obtained after sintering in this embodiment is 98.5%, and the hardness is 560 Hv 0.2, the compressive yield strength is 1150 MPa, the compressive strength is 1710 MPa, and the compressive deformation rate is 38.5%. The load for the friction and wear test is 10 N, the counter friction pair is a silicon nitride ceramic ball with a diameter of 6 mm, the reciprocating friction time is 30 min, the linear velocity is 0.012 m / s, the average friction coefficient in the seawater environment is 0.07, and the wear rate is 3.0×10 -6 mm 3 / Nm. As Figure 1 shown in (a), the microstructure of the NiCr-15Nb-15Mo material is dense, without obvious pores and defects, and the second phase is evenly distributed. The wear scar in the seawater environment is as Figure 1 shown in (b), there is no serious spalling and cracks in the wear scar, only relatively shallow plough grooves. Comparative Example 1

[0022] The difference from Example 1 is that the component ratio of the material is 85 wt% NiCr powder, 0 wt% niobium powder, and 15 wt% molybdenum powder.

[0023] The density of the sintered material is 98.3%, and the hardness is 253 Hv 0.2 , the compressive yield strength is 553 MPa, and there is no crushing. The average friction coefficient in the seawater environment is 0.12, and the wear rate reaches 4.7×10 -5 mm 3 / Nm. Comparative Example 2

[0024] The difference from Example 1 is that the component ratio of the material is 85 wt% NiCr powder, 15 wt% niobium powder, and 0 wt% molybdenum powder.

[0025] The density of the sintered material is 97.9%, and the hardness is 415 Hv 0.2 , the compressive yield strength is 830 MPa, the compressive strength is 2303 MPa, and the compressive deformation rate is 45%. The average friction coefficient in the seawater environment is 0.24, and the wear rate reaches 1.4×10 -5 mm 3 / Nm. As Figure 2 shown in (a), in the NiCr-15Nb material, the second phase is evenly distributed. The wear scar morphology in the seawater environment is as Figure 2 shown in (b), the macroscopic morphology of the wear scar has an increased width compared to that of the NiCr-15Nb-15Mo material, and there are cracks and spalling in the wear scar. Example 2

[0026] The difference from Example 1 is that the component ratio of the material is 80 wt% NiCr alloy powder, 10 wt% niobium powder, and 10 wt% molybdenum powder.

[0027] The density of the sintered material is 97.8%, and the hardness is 363 Hv 0.2 , the compressive yield strength is 984 MPa, and there is no crushing. The average friction coefficient in the seawater environment is 0.10, and the wear rate is 1.8×10 -5 mm 3 / Nm. Example 3

[0028] The difference from Example 1 is that the material is prepared by replacing niobium powder and molybdenum powder with tantalum powder and tungsten powder of equivalent particle size respectively, and its component ratio is 70 wt% NiCr alloy powder, 15 wt% tantalum powder, and 15 wt% tungsten powder.

[0029] The density of the sintered material is 98.5%, and the hardness is 535 Hv 0.2 , the compressive yield strength is 1356 MPa, the compressive strength is 2600 MPa, and the compressive deformation rate is 40%. The average friction coefficient in the seawater environment is 0.10, and the wear rate is 1.8×10 -5 mm 3 / Nm. Example 4

[0030] In this example, a self-lubricating alloy that can replace oil lubrication in a seawater environment includes raw materials with the following mass percentages: 70 wt% of FGH97 alloy powder with a particle size of 40 μm, 15 wt% of niobium powder with a particle size of about 20 μm, and 15 wt% of molybdenum powder with a particle size of 4 μm. The composition of the FGH97 alloy powder is: C 0.04 wt%, Co 15.9 wt%, Cr 8.9 wt%, W 5.6 wt%, Mo 3.8 wt%, Al 5.0 wt%, Ti 1.8 wt%, Nb 2.6 wt%, Hf 0.3 wt%, and the balance is Ni. It is mixed with niobium powder and molybdenum powder with a micron-sized FGH97 alloy powder as the matrix and prepared by spark plasma sintering. The preparation method includes the following steps:

[0031] (1) Powder mixing: Weigh the original powders according to the ratio. The ball milling process uses a stainless steel ball milling tank and stainless steel balls, and the ball-to-material mass ratio is 10:1. After the original powders are loaded into the ball milling tank, a planetary ball mill is used to mix the powders evenly. The rotation speed is 300 r / min, and it runs intermittently, stopping for 15 minutes every 30 minutes of operation. After ball milling for 8 hours, the obtained powder is placed in a drying oven for drying. The drying temperature is 45 °C, and the drying time is 2 hours.

[0032] (2) Cold pressing with mold installation: First, uniformly spray boron nitride in the graphite mold for sintering, then fill the inner wall of the graphite mold with graphite paper. Put the finally evenly mixed and dried powder into the graphite mold and compact it with a hydraulic press. The hydraulic press pre-presses the graphite mold filled with powder at 25 MPa and holds the pressure for 60 s; use a universal testing machine to pressurize to 70 kN, hold for 2 min and then unload. (3) Spark plasma sintering: Put the graphite mold filled with powder into a sintering furnace with a vacuum degree of 5×10 -3 atm, and heat it in two stages: First, raise the temperature to 1090 °C at a heating rate of 40 °C / min; then raise the temperature to 1100 °C at a heating rate of 20 °C / min. Finally, keep it at 1100 °C for 20 min and then cool it to room temperature with the furnace at a cooling rate of 25 °C / min. The sintering pressure is 40 MPa.

[0033] After sintering in this example, the density of the material is 98.3%, the hardness is 585 Hv 0.2 , the compressive yield strength is 1180 MPa, the compressive strength is 1870 MPa, and the compression deformation rate is 34%. The load of the friction and wear test is 10 N, the counterbody is a silicon nitride ceramic ball with a diameter of 6 mm, the reciprocating friction time is 30 min, the linear velocity is 0.012 m / s, the average friction coefficient in the seawater environment is 0.09, and the wear rate is 5.6×10 -6 mm 3 / Nm. Example 5

[0034] In this example, a self-lubricating alloy that can replace oil lubrication in a seawater environment includes the following raw materials by mass percentage: 70 wt% of In738 alloy powder with a particle size of 30 μm, 15 wt% of niobium powder with a particle size of about 15 μm, 15 wt% of molybdenum powder with a particle size of about 4 μm. The composition of the In738 alloy powder is: C 0.17 wt%, Co 8.12 wt%, Cr 15.92 wt%, W 2.61 wt%, Mo 1.8 wt%, Al 3.6 wt%, Ti 3.49 wt%, Nb 0.94 wt%, Ta 1.78 wt%, and the balance is Ni. Based on the micron-sized In738 alloy powder as the matrix, it is mixed with niobium powder and molybdenum powder and prepared by spark plasma sintering. The preparation method includes the following steps: (1) Powder mixing: Weigh the raw powders according to the ratio. For the ball milling process, use a stainless-steel ball milling tank and stainless-steel balls, with a ball-to-material mass ratio of 10:1. After loading the raw powders into the ball milling tank, use a planetary ball mill to mix the powders evenly at a rotational speed of 300 r / min, operating intermittently, stopping for 15 min every 30 min of operation. After ball milling for 8 h, place the obtained powder in a drying oven for drying at a drying temperature of 45 °C for 2 h.

[0035] (2) Cold pressing in the mold: First, evenly spray boron nitride in the graphite mold for sintering, then line the inner wall of the graphite mold with graphite paper. Place the finally evenly mixed and dried powder into the graphite mold and compact it with a hydraulic press. The hydraulic press applies a pre-pressure of 30 MPa to the graphite mold filled with the powder and holds the pressure for 60 s; use a universal testing machine to apply pressure up to 80 kN and hold for 2 min before unloading; (3) Spark plasma sintering: Place the graphite mold filled with the powder into a sintering furnace with a vacuum degree of 5×10 -3 atm, and heat it in two stages: First, raise the temperature to 1090 °C at a heating rate of 40 °C / min; then raise the temperature to 1100 °C at a heating rate of 20 °C / min. Finally, hold the temperature at 1100 °C for 20 min and then cool it to room temperature with the furnace at a cooling rate of 25 °C / min. The sintering pressure is 40 MPa.

[0036] The density of the sintered material is 98.5%, the hardness is 550 Hv 0.2 , the compressive yield strength is 1200 MPa, the compressive strength is 1780 MPa, and the compression deformation rate is 35%. The load for the friction and wear test is 10 N, the counterbody is a silicon nitride ceramic ball with a diameter of 6 mm, the reciprocating friction time is 30 min, the linear velocity is 0.012 m / s, the average friction coefficient in the seawater environment is 0.08, and the wear rate is 5.8×10 -6 mm 3 / Nm. Example 6

[0037] In this example, a self-lubricating alloy that can replace oil lubrication in a seawater environment includes raw materials with the following mass percentages: 70 wt% of CoCr alloy powder with a particle size of 35 μm, 15 wt% of niobium powder with a particle size of about 15 μm, and 15 wt% of molybdenum powder with a particle size of about 4 μm. The composition of the CoCr powder is: Co 80 wt%, Cr 20 wt%. Mix the micron-sized CoCr alloy powder as the matrix with niobium powder and molybdenum powder, and prepare it by spark plasma sintering. The preparation method includes the following steps: (1) Powder mixing: Weigh the raw powders according to the ratio. For the ball milling process, use a stainless steel ball milling tank and stainless steel balls with a ball-to-material mass ratio of 10:1. After loading the raw powders into the ball milling tank, use a planetary ball mill to mix the powders evenly at a rotational speed of 300 r / min, operating intermittently. It runs for 30 min and then stops for 15 min. After ball milling for 8 h, place the obtained powder in a drying oven for drying at a temperature of 45 °C for 2 h.

[0038] (2) Cold pressing in the mold: First, evenly spray boron nitride on the graphite mold for sintering, and then line the inner wall of the graphite mold with graphite paper. Put the finally evenly mixed and dried powder into the graphite mold and compact it with a hydraulic press. The hydraulic press applies a pre-pressure of 20 MPa to the graphite mold filled with the powder and holds the pressure for 120 s; use a universal testing machine to apply pressure up to 76 kN and hold for 3 min before unloading; (3) Spark plasma sintering: Place the graphite mold filled with the powder into a sintering furnace with a vacuum degree of 5×10 -3 atm. Heat it up in two stages: First, raise the temperature to 1090 °C at a heating rate of 45 °C / min; then raise the temperature to 1120 °C at a heating rate of 25 °C / min. Finally, hold the temperature at 1120 °C for 10 min and then cool it to room temperature with the furnace at a cooling rate of 25 °C / min. The sintering pressure is 35 MPa.

[0039] The density of the material after sintering in this example is 98.3%, the hardness is 535 Hv 0.2 , the compressive yield strength is 1150 MPa, the compressive strength is 1750 MPa, and the compression deformation rate is 39%. The load for the friction and wear test is 10 N, the counterbody is a silicon nitride ceramic ball with a diameter of 6 mm, the reciprocating friction time is 30 min, the linear velocity is 0.012 m / s, and the average friction coefficient in a seawater environment is 0.08, and the wear rate is 6.2×10 -6 mm 3 / Nm. Example 7

[0040] In this example, a self-lubricating alloy that can replace oil lubrication in a seawater environment includes raw materials with the following mass percentages: 70 wt% of CoCrW alloy powder with a particle size of 50 μm, 15 wt% of niobium powder with a particle size of about 15 μm, and 15 wt% of molybdenum powder with a particle size of about 4 μm. The composition of the CoCrW powder is: Co 66 wt%, Cr 27 wt%, W 7 wt%. Based on the micron-sized CoCrW alloy powder as the matrix, it is mixed with niobium powder and molybdenum powder and prepared by spark plasma sintering. The preparation method includes the following steps: Powder mixing: The raw powders are weighed according to the ratio. For the ball milling process, a stainless - steel ball - milling tank and stainless - steel balls are used, and the mass ratio of balls to materials is 10:1. After the raw powders are loaded into the ball - milling tank, a planetary ball mill is used to mix the powders evenly at a rotational speed of 300 r / min, operating intermittently. It runs for 30 min and then stops for 15 min. After ball - milling for 8 h, the obtained powder is placed in a drying oven for drying. The drying temperature is 45 °C and the drying time is 2 h. Cold pressing in the mold: First, boron nitride is evenly sprayed in the graphite mold for sintering, and then graphite paper is filled on the inner wall of the graphite mold. The finally evenly mixed and dried powder is put into the graphite mold and compacted by a hydraulic press. The hydraulic press pre - presses the graphite mold filled with the powder body at 20 MPa and holds the pressure for 120 s; then it is pressurized to 77 kN using a universal testing machine and held for 2 min before unloading. (3)Spark plasma sintering: The graphite mold filled with the powder body is placed in a sintering furnace with a vacuum degree of 5×10 -3 atm. It is heated in two stages: First, the temperature is raised to 1090 °C at a heating rate of 45 °C / min; then the temperature is raised to 1120 °C at a heating rate of 25 °C / min. Finally, it is held at 1120 °C for 10 min and then cooled to room temperature with the furnace at a cooling rate of 25 °C / min. The sintering pressure is 35 MPa.

[0041] The density of the sintered material in this example is 98.5%, the hardness is 505 Hv 0.2 , the compressive yield strength is 1170 MPa, the compressive strength is 1780 MPa, and the compression deformation rate is 36%. The load for the friction and wear test is 10 N, the counter - part is a silicon nitride ceramic ball with a diameter of 6 mm, the reciprocating friction time is 30 min, the linear velocity is 0.012 m / s, and the average friction coefficient in a seawater environment is 0.09, and the wear rate is 7.5×10 -6 mm 3 / Nm. Example 8

[0042] In this example, a self - lubricating alloy that can replace oil lubrication in a seawater environment includes raw materials with the following mass percentages: 70 wt% of GH605 alloy powder with a particle size of 50 μm, 15 wt% of niobium powder with a particle size of about 10 μm, and 15 wt% of molybdenum powder with a particle size of about 4 μm. The composition of the GH605 powder is: Ni 10.46 wt%, Cr 19.66 wt%, W 14.95 wt%, C 0.096 wt%, Mn 1.55 wt%, Fe 2.11 wt%, and the balance is Co. Based on the micron - sized GH605 alloy powder as the matrix, it is mixed with niobium powder and molybdenum powder and prepared by spark plasma sintering. Its preparation method includes the following steps: (1) Powder mixing: Weigh the original powders according to the ratio. For the ball milling process, use a stainless steel ball milling tank and stainless steel balls, with a ball-to-material mass ratio of 10:1. After loading the original powders into the ball milling tank, use a planetary ball mill to mix the powders evenly at a rotational speed of 300 r / min, operating intermittently. It runs for 30 min and then stops for 15 min. After ball milling for 8 h, place the obtained powders in a drying oven for drying at a drying temperature of 45 °C for 2 h.

[0043] (2) Cold pressing in mold: First, evenly spray boron nitride in the graphite mold for sintering, and then line the inner wall of the graphite mold with graphite paper. Put the finally evenly mixed and dried powders into the graphite mold and compact them with a hydraulic press. The hydraulic press applies a pre-pressure of 20 MPa to the graphite mold filled with powder and holds the pressure for 120 s; use a universal testing machine to apply pressure up to 73 kN and hold for 2 min before unloading; (3) Spark plasma sintering: Place the graphite mold filled with powder into a sintering furnace with a vacuum degree of 5×10 -3 atm. Heat it up in two stages: First, raise the temperature to 1090 °C at a heating rate of 45 °C / min; then raise the temperature to 1120 °C at a heating rate of 25 °C / min. Finally, hold the temperature at 1120 °C for 10 min and then cool it to room temperature with the furnace at a cooling rate of 25 °C / min. The sintering pressure is 35 MPa.

[0044] The density of the material after sintering in this example is 98.4%, the hardness is 509 Hv 0.2 , the compressive yield strength is 1160 MPa, the compressive strength is 1750 MPa, and the compression deformation rate is 37%. The load for the friction and wear test is 10 N, the counterbody is a silicon nitride ceramic ball with a diameter of 6 mm, the reciprocating friction time is 30 min, the linear velocity is 0.012 m / s, the average friction coefficient in a seawater environment is 0.08, and the wear rate is 8.6×10 -6 mm 3 / Nm. Example 9

[0045] In this example, a self-lubricating alloy that can replace oil lubrication in a seawater environment includes raw materials with the following mass percentages: 70 wt% FeCr powder with a particle size of 45 μm, 15 wt% niobium powder with a particle size of about 10 μm, 15 wt% molybdenum powder with a particle size of about 4 μm. The composition of the FeCr powder is: Fe 80 wt%, Cr 20 wt%. Based on the micron-sized FeCr powder as the matrix, it is mixed with niobium powder and molybdenum powder and prepared by spark plasma sintering. Its preparation method includes the following steps: (1)Powder mixing: Weigh the raw powders according to the ratio. For the ball milling process, use a stainless steel ball milling tank and stainless steel balls, with a ball-to-material mass ratio of 10:1. After loading the raw powders into the ball milling tank, use a planetary ball mill to mix the powders evenly at a rotational speed of 300 r / min, operating intermittently. It stops for 15 minutes every 30 minutes of operation. After ball milling for 8 hours, place the obtained powders in a drying oven for drying. The drying temperature is 45 °C and the drying time is 2 hours.

[0046] (2)Cold pressing in the mold: First, evenly spray boron nitride in the graphite mold for sintering, and then line the inner wall of the graphite mold with graphite paper. Put the finally evenly mixed and dried powders into the graphite mold and compact them with a hydraulic press. The hydraulic press applies a pre-pressure of 20 MPa to the graphite mold filled with the powder and holds the pressure for 120 s; use a universal testing machine to apply pressure up to 75 kN, hold for 2 minutes and then unload. (3)Spark plasma sintering: Put the graphite mold filled with the powder into a sintering furnace with a vacuum degree of 5×10 -3 atm. First, raise the temperature to 1050 °C at a heating rate of 50 °C / min; then raise the temperature to 1100 °C at a heating rate of 15 °C / min. Finally, after holding at 1100 °C for 15 minutes, cool it to room temperature in the furnace at a cooling rate of 25 °C / min. The sintering pressure is 45 MPa.

[0047] The density of the sintered material in this example is 98.4%, the hardness is 520 Hv 0.2 , the compressive yield strength is 1140 MPa, the compressive strength is 1710 MPa, and the compression deformation rate is 37%. The load for the friction and wear test is 10 N, the counterbody is a silicon nitride ceramic ball with a diameter of 6 mm, the reciprocating friction time is 30 minutes, the linear velocity is 0.012 m / s, the average friction coefficient in the seawater environment is 0.08, and the wear rate is 9.3×10 -6 mm 3 / Nm. Example 10

[0048] In this embodiment, a self-lubricating alloy that can replace oil lubrication in a seawater environment includes raw materials with the following mass percentages: 70 wt% of stainless steel powder with a particle size of 40 μm, 15 wt% of niobium powder with a particle size of about 10 μm, 15 wt% of molybdenum powder with a particle size of about 4 μm. The composition of the 316 stainless steel powder is: C 0.04 wt%, Ni 12.40 wt%, Cr 17.40 wt%, Si 0.39 wt%, Mo 2.63 wt%, Mn 1.57 wt%, S 0.001 wt%, P 0.02 wt%, N 0.06 wt%, and the balance is Fe. Using micron-sized 316 stainless steel powder as the matrix, it is mixed with niobium powder and molybdenum powder and prepared by spark plasma sintering. The preparation method includes the following steps: (1) Powder mixing: Weigh the original powders according to the ratio. The ball milling process uses a stainless steel ball milling tank and stainless steel balls, and the ball-to-material mass ratio is 10:1. After loading the original powders into the ball milling tank, use a planetary ball mill to mix the powder evenly at a rotation speed of 300 r / min, running intermittently, stopping for 15 minutes every 30 minutes of operation. After ball milling for 8 hours, place the obtained powder in a drying oven for drying. The drying temperature is 45 °C, and the drying time is 2 hours; (2) Cold pressing in a mold: First, spray boron nitride evenly in the graphite mold for sintering, and then fill graphite paper on the inner wall of the graphite mold. Place the finally evenly mixed and dried powder into the graphite mold and compact it with a hydraulic press. The hydraulic press applies a pre-pressure of 20 MPa to the graphite mold filled with the powder and holds the pressure for 120 s; Use a universal testing machine to apply pressure up to 75 kN and hold for 3 minutes before unloading.

[0049] (2) Spark plasma sintering: Place the graphite mold filled with the powder into a sintering furnace with a vacuum degree of 5×10 -3 atm, and heat it in two stages: First, raise the temperature to 1050 °C at a heating rate of 50 °C / min; then raise the temperature to 1100 °C at a heating rate of 15 °C / min. Finally, keep it at 1100 °C for 15 minutes and then cool it to room temperature with the furnace at a cooling rate of 25 °C / min. The sintering pressure is 45 MPa.

[0050] The density of the sintered material in this embodiment is 98.5%, the hardness is 540 Hv 0.2 , the compressive yield strength is 1130 MPa, the compressive strength is 1690 MPa, and the compression deformation rate is 39%. The load of the friction and wear test is 10 N, the counter friction pair is a silicon nitride ceramic ball with a diameter of 6 mm, the reciprocating friction time is 30 minutes, the linear velocity is 0.012 m / s, and the average friction coefficient in a seawater environment is 0.08, and the wear rate is 6.8×10 -6 mm 3 / Nm. Example 11

[0051] In this example, a self-lubricating alloy that can replace oil lubrication in a seawater environment includes raw materials with the following mass percentages: 70 wt% of 304 stainless steel powder with a particle size of 30 μm, 15 wt% of niobium powder with a particle size of about 20 μm, and 15 wt% of molybdenum powder with a particle size of about 4 μm. The composition of the 304 stainless steel powder is: C 0.033 wt%, Ni 8.27 wt%, Cr 18.07 wt%, Si 0.33 wt%, Mn 1.20 wt%, S 0.0025 wt%, P 0.028 wt%, and the balance is Fe. Based on micron-sized 304 stainless steel powder as the matrix, it is mixed with niobium powder and molybdenum powder and prepared by spark plasma sintering. The preparation method includes the following steps: (1) Powder mixing: Weigh the original powders according to the ratio. The ball milling process uses a stainless steel ball milling tank and stainless steel balls, and the ball-to-material mass ratio is 10:1. After the original powders are loaded into the ball milling tank, a planetary ball mill is used to mix the powders evenly at a rotation speed of 300 r / min, operating intermittently, stopping for 15 minutes every 30 minutes of operation. After ball milling for 8 hours, the obtained powders are placed in a drying oven for drying. The drying temperature is 45 °C, and the drying time is 2 hours.

[0052] (2) Cold pressing in the mold: First, spray boron nitride evenly in the graphite mold for sintering, and then line the inner wall of the graphite mold with graphite paper. The finally evenly mixed and dried powders are put into the graphite mold and compacted by a hydraulic press. The hydraulic press pre-presses the graphite mold filled with the powder body at 25 MPa and holds the pressure for 60 s; use a universal testing machine to apply pressure up to 75 kN and hold for 2 minutes before unloading; (3) Spark plasma sintering: Place the graphite mold filled with the powder body into a sintering furnace with a vacuum degree of 5×10 -3 atm, and heat it up in two stages: First, raise the temperature to 1050 °C at a heating rate of 50 °C / min; then raise the temperature to 1100 °C at a heating rate of 15 °C / min. Finally, after holding at 1100 °C for 15 minutes, cool it to room temperature with the furnace at a cooling rate of 25 °C / min. The sintering pressure is 45 MPa.

[0053] The density of the sintered material in this example is 98.3%, the hardness is 509 Hv 0.2 , the compressive yield strength is 1135 MPa, the compressive strength is 1720 MPa, and the compression deformation rate is 36%. The load for the friction and wear test is 10 N, the counterbody is a silicon nitride ceramic ball with a diameter of 6 mm, the reciprocating friction time is 30 minutes, the linear velocity is 0.012 m / s, and the average friction coefficient in a seawater environment is 0.09, and the wear rate is 8.5×10-6 mm 3 / Nm。 Example 12

[0054] The difference between this example and Example 11 is that materials are prepared by replacing niobium powder and molybdenum powder with tantalum powder and tungsten powder of equivalent particle size respectively, and the composition ratio is 70 wt% of 304 stainless steel powder, 15 wt% of tantalum powder, and 15 wt% of tungsten powder.

[0055] The average friction coefficient of the sintered material in the seawater environment is 0.10, and the wear rate is 7.3×10 -6 mm 3 / Nm。 Example 13

[0056] The difference between this example and Example 11 is that materials are prepared by replacing niobium powder and molybdenum powder with tantalum powder and tungsten powder of equivalent particle size respectively, and the composition ratio is 80 wt% of 304 stainless steel powder, 10 wt% of tantalum powder, and 10 wt% of tungsten powder.

[0057] The average friction coefficient of the sintered material in the seawater environment is 0.09, and the wear rate is 6.2×10 -6 mm 3 / Nm。

[0058] The implementation results show that the embodiments of the present invention can obtain a corrosion-resistant, high-strength and high-toughness self-lubricating alloy that can replace oil lubrication, and its optimized performance indicators are: the compressive strength reaches more than 1600 MPa, and the compressive deformation rate of crushing reaches more than 32%; in the seawater environment, the reciprocating friction coefficient ≤ 0.10, and the wear rate ≤ 2×10 -5 mm 3 / Nm。

[0059] The applicant declares that although the detailed composition and preparation method of the present invention have been shown and described, for those skilled in the art, the present invention is not limited to being implemented depending on the above detailed composition and preparation method. Any improvement of the present invention, substitution of product raw materials, addition of auxiliary components, etc. are within the protection scope and public disclosure scope of the present invention.

Claims

1. A self-lubricating alloy that can replace oil lubrication in a seawater environment, characterized in that, It includes raw materials with the following mass percentages: 70 - 80% of corrosion-resistant nickel-based alloy powder, cobalt-based alloy powder or iron-based alloy powder; its particle size is 20 - 50 μm; 10 - 20% of niobium powder, its particle size is 10 - 20 μm; 10 - 20% of molybdenum powder, its particle size is 2 - 5 μm The alloy uses corrosion-resistant nickel-based alloy powder, cobalt-based alloy powder or iron-based alloy powder as the base powder, is mixed with niobium powder and molybdenum powder, and is prepared by spark plasma sintering. It has a multi-level grain size microstructure, and its performance indicators are: compressive strength ≥ 1600 MPa, compression deformation rate ≥ 32%; seawater reciprocating friction coefficient ≤ 0.10, wear rate ≤ 2.0×10 -5 mm 3 / Nm.

2. The self-lubricating alloy capable of replacing oil lubrication in a seawater environment according to claim 1, characterized in that, The base powder is selected from at least one of the following: Nickel-based alloy powder: NiCr, FGH97, In738 superalloy powder; Cobalt-based alloy powder: CoCr, CoCrW, GH605 superalloy powder; Iron-based alloy powder; FeCr, 316 stainless steel, 304 stainless steel or iron-based superalloy powder.

3. A self-lubricating alloy that can replace oil lubrication in a seawater environment according to claim 1, characterized in that, The niobium powder and molybdenum powder can be replaced by tantalum powder and tungsten powder respectively.

4. A method for preparing a self-lubricating alloy capable of replacing oil lubrication in a seawater environment according to any one of claims 1 to 3, characterized in that, It includes the following steps: (1) Powder mixing: Use a planetary ball mill to mix the original powders weighed according to the formula, with a rotation speed of 200 - 400 r / min, intermittent operation, stopping for 15 min every 30 - 60 min of operation, and the ball milling time is 8 h. Place the ball-milled powder in a drying oven to dry, and obtain powder A; (2) Die filling and cold pressing: First, evenly spray boron nitride in the graphite mold for sintering, then fill graphite paper on the inner wall of the graphite mold, and then put powder A into the graphite mold. Use a hydraulic press to pre-press the filled powder and hold for 60 - 120 s; Use a universal testing machine to apply pressure and hold for 2 - 3 min and then unload; (3) Spark Plasma Sintering: Place the graphite mold filled with powder into a sintering furnace with a vacuum degree less than 1×10 -2 atm. Heat it in two stages: First, heat it to 1050 - 1090 °C at a rate of 40 - 50 °C / min, and then heat it to 1100 - 1130 °C at a rate of 15 - 25 °C / min; after holding for 10 - 20 min, cool it slowly with the furnace, and the sintering pressure is 35 - 50 MPa.

5. The preparation method of a self-lubricating alloy capable of replacing oil lubrication in a seawater environment according to claim 4, characterized in that, In step (1), the ball milling process uses a stainless steel ball milling tank and stainless steel balls, and the ball-to-material mass ratio is 10:

1. The ball milling tank filled with the original powder will be placed in a planetary ball mill.

6. The preparation method of a self-lubricating alloy capable of replacing oil lubrication in a seawater environment according to claim 4, characterized in that, In step (1), the drying temperature of the ball-milled powder in the drying oven is 45 °C, and the drying time is 2 h.

7. The preparation method of a self-lubricating alloy capable of replacing oil lubrication in a seawater environment according to claim 5, characterized in that, In step (2), the hydraulic press pre-presses the filled powder A at 20 - 30 MPa and holds for 60 - 120 s; Use a universal testing machine to apply pressure up to 70 - 80 kN and hold for 2 - 3 min.

8. The preparation method of a self-lubricating alloy capable of replacing oil lubrication in a seawater environment according to claim 5, characterized in that, In step (3), the cooling rate of slow cooling with the furnace is 25 °C / min, and the furnace temperature drops to room temperature.

Images