Self-lubricating titanium-based metal ceramic and preparation method thereof

Abstract

The invention discloses a self-lubricating titanium-based metal ceramic and a production process thereof. The self-lubricating titanium-based metal ceramic is prepared from Ti (C0.7, N0.3) powder, TiB2 powder, HEA fibers, h-BN (at) KH550 and Y2O3 powder. The production process comprises the following steps: 1) preparing high-entropy alloy coated carbon fibers through laser ablation; 2) performing segmented ball milling to realize uniform dispersion of a hard phase and a lubricating phase; (3) a surface Ti-rich (C0.7, N0.3) hard layer and a core chromium-cobalt-nickel alloy binding phase are constructed through gradient carburizing and sintering; and 4) performing hot isostatic pressing densification treatment. By utilizing the crack bridging effect of HEA fibers and the directional lubrication characteristic of h-BN and cooperating with the carburizing gradient structure design, the material has ultrahigh hardness, excellent toughness and wide-temperature-range self-lubricating performance at the same time, and is particularly suitable for high-strength operation under the high-temperature condition.

Description

Technical Field

[0001] The present invention relates to the technical field of metal ceramic materials, in particular to a self-lubricating titanium-based metal ceramic and a preparation method thereof. Background Art

[0002] Cermets are composite materials composed of ceramic phases (such as TiC, TiN, TiB2) and metal phases (such as Ni, Co, and Fe-based alloys). They combine the high hardness and wear resistance of ceramics with the toughness of metals and are widely used in cutting tools, high-temperature aerospace components, and wear-resistant coatings. Among them, titanium-based cermets (with Ti(C,N) or TiB2 as a matrix) have become a research hotspot for modern high-performance tool materials due to their excellent chemical stability, high-temperature strength, and oxidation resistance.

[0003] However, traditional titanium-based cermets still face the following problems under high-speed cutting or high-temperature friction conditions:

[0004] The high coefficient of friction leads to increased tool wear and shortened tool life;

[0005] It is brittle and easily breaks under impact loads;

[0006] The high-temperature lubrication performance is insufficient and it is difficult to adapt to extreme working conditions (such as dry cutting and aircraft engine components).

[0007] Therefore, the development of titanium-based cermets with self-lubricating properties has become a key direction to enhance their engineering application value. Summary of the Invention

[0008] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a self-lubricating titanium-based cermet and a preparation method thereof.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] The present invention first proposes a self-lubricating titanium-based cermet, comprising the following raw materials: 60-70 parts of Ti(C 0.7 ,N 0.3 )powder;

[0011] 20-25 parts of TiB2 powder;

[0012] 12-18 parts of HEA fiber, which is wrapped with high entropy alloy Fe 40 Ni 20 Co 20 Cr 20 of carbon fiber;

[0013] 1-2 parts of h-BN@KH550, i.e., h-BN modified with KH550;

[0014] 1-3 parts of Y2O3 powder;

[0015] The preparation method of the HEA fiber comprises the following steps:

[0016] S1. Raw material preparation

[0017] The carbon fiber is polyacrylonitrile-based T700 grade carbon fiber with a single filament diameter of 7 μm and a length of 50-100 μm.

[0018] The carbon fiber was ultrasonically cleaned with acetone three times for 15 minutes each time to remove the epoxy resin coating on the surface, and then immersed in a 68% by mass nitric acid solution at 100° C. for 120 minutes to activate the fiber surface, and then rinsed with deionized water until neutral, vacuum dried at 120° C. for 2 hours, and heat treated at 800° C. in an argon environment for 1 hour, and annealed to remove the surface amorphous carbon layer, thereby obtaining raw material A;

[0019] S2. Laser scanning ablation process

[0020] Raw material A is immersed in high entropy alloy Fe 40 Ni 20 Co 20 Cr 20 The precursor solution was ultrasonically dispersed for 15 minutes; the precursor was uniformly attached to the fiber surface by the pulling method at a speed of 2 mm / s; the precursor was dried at 80 ° C for 30 minutes; the raw material A with the precursor attached was placed on a quartz substrate and placed in a laser processing chamber; the vacuum was evacuated to 10 -3 Pa and then filled with high-purity argon gas.

[0021] After laser treatment, the mixture was naturally cooled under argon protection to obtain raw material B;

[0022] The laser scanning ablation process is used to prepare high entropy alloys, thereby wrapping carbon fibers. The resulting HEA fibers can precisely control the formation process of the alloy layer, ensuring the uniformity and density of the alloy layer. This process not only improves the performance of the material, but also improves production efficiency and quality control.

[0023] The laser pulse causes the local temperature of the metal salt precursor to reach over 2500K within 5ns, and undergoes the following transformations:

[0024] Thermal decomposition:

[0025] M(NO3) x →MO x / 2 +NO2↑+O2↑;

[0026] reduction:

[0027] MO x / 2 →M+O2↑;

[0028] Alloying: Fe+Ni+Co+Cr→FeNiCoCr high entropy alloy;

[0029] Then a uniform and dense alloy protective layer is formed on the carbon fiber surface. At the same time, the laser scanning ablation process has an ultra-fast cooling rate (≥10 6 K / s) inhibits element segregation.

[0030] S3, HEA fiber post-treatment

[0031] The raw material B was annealed in an atmosphere of 5% H2 / 95% Ar mixed gas in a tubular furnace, heated to 800°C at a rate of 5°C / min, kept warm for 1 hour, and then cooled to room temperature at a rate of 3°C / min to obtain high entropy alloy wrapped carbon fiber, i.e., HEA fiber.

[0032] Preferably, in the laser scanning ablation process, an Nd:YAG pulse laser is used, and the equipment parameters are as follows: wavelength 1064nm; pulse width 5ns; repetition frequency 10Hz; spot diameter 50μm; scanning speed 50mm / s;

[0033] Laser parameters are set to: energy density 3J / cm 2 ; Scanning times 3 times; Scanning interval 30μm.

[0034] Preferably, the preparation method of h-BN@KH550 comprises the following steps:

[0035] Sodium hydroxide and deionized water were added to a round-bottom flask and stirred to dissolve. Hexagonal boron nitride (h-BN) powder was then added and refluxed at 120°C for 24 hours. After filtration, washing twice with water, and drying, h-BN powder with surface hydroxyl activated, i.e., h-BN@OH, was obtained.

[0036] Anhydrous ethanol and 3-aminopropyltriethoxysilane were added to a beaker, the pH was adjusted to 3-5 with acetic acid and hydrolyzed for 30 minutes to obtain a mixed solution, which was then added to a round-bottom flask containing h-BN@OH and refluxed at 80°C for 4 hours.

[0037] After the reaction, the mixture was filtered, washed with anhydrous ethanol and dried in an oven at 110 °C for 12 h to obtain KH-550-modified h-BN powder, i.e., h-BN@KH550.

[0038] Preferably, the high entropy alloy Fe 40 Ni 20 Co 20 Cr 20The precursor solution was prepared by weighing 23.17-34.75 parts of ferric nitrate hexahydrate, 7.92-11.88 parts of nickel nitrate hexahydrate, 7.91-11.87 parts of cobalt nitrate hexahydrate, and 12.30-18.46 parts of chromium nitrate hexahydrate, respectively, dissolving them in 160-240 parts of deionized water, adding 0.4-0.6 parts of polyvinyl pyrrolidone as a dispersant, and magnetically stirring for 30 minutes to obtain a high entropy alloy Fe 40 Ni 20 Co 20 Cr 20 Precursor solution.

[0039] Preferably, the high entropy alloy Fe 40 Ni 20 Co 20 Cr 20 The mass ratio with raw material A is 2:1.

[0040] Preferably, the mass ratio of sodium hydroxide, deionized water and hexagonal boron nitride is 2:10:1; the mass ratio of anhydrous ethanol to 3-aminopropyltriethoxysilane is 20:1; and the mass ratio of the mixed solution to h-BN@OH is 21:1.

[0041] The method for preparing the self-lubricating titanium-based cermet comprises the following steps:

[0042] 1) Raw material preparation:

[0043] Ti(C 0.7 ,N 0.3 ) powder, TiB2 powder, and Y2O3 powder are uniformly mixed to obtain composite powder A;

[0044] 2) Ball milling and pressing:

[0045] After placing composite powder A into the tungsten carbide ball mill of the QM-3SP4 planetary ball mill, weigh grinding balls according to a ball-to-material ratio of 10:1 and place them into the ball mill. Dry milling is performed at a speed of 100 r / min for 5 h without adding liquid to obtain the dry-milled powder, i.e., composite powder B.

[0046] HEA fiber and h-BN@KH550 were added to composite powder B and pre-mixed manually for 5 min to obtain composite powder C.

[0047] After placing composite powder C into the tungsten carbide hard alloy ball mill of the QM-3SP4 planetary ball mill, weigh grinding balls at a ball-to-material ratio of 10:1, with tungsten carbide balls of Φ5 mm and Φ10 mm in a ratio of 1:1, and place them into the ball mill. Then, pour in anhydrous ethanol until the anhydrous ethanol just covers the powder, and wet grind at a speed of 150 r / min for 10 h to obtain composite powder D.

[0048] Pour the composite powder D into a stainless steel dish, place it in a DZF-6050 vacuum drying oven, dry it at 70°C for 12 hours, and then pass it through a 100-mesh sieve;

[0049] The dried composite powder D was placed in a stainless steel mold and pre-pressed using a hydraulic press at a pressure of 5 MPa for 5 minutes to obtain composite powder E.

[0050] The segmented ball milling process (dry milling and wet milling) is used. In the dry milling stage, the hard phase

[0051] [Ti(C 0.7 ,N 0.3 ) / TiB2] is crushed and refined in a solvent-free environment (particle size is reduced to 0.5-1μm) to prevent the fibers from being cut by hard particles during subsequent wet grinding.

[0052] During the wet grinding stage, the h-BN powder in the ethanol medium formed a chemical bond with the titanium matrix through the amino group (-NH2) of the KH-550 silane coupling agent, achieving uniform dispersion.

[0053] By using the segmented ball milling process, the carbon fiber breakage rate is greatly reduced, ensuring the integrity of the fiber. At the same time, h-BN is arranged in a layered and directional manner in the matrix, and the room temperature friction coefficient is reduced to 0.15, making the lubricating phase distribution more uniform and neat.

[0054] 3) Sintering

[0055] Use HIGH-MULTI-5000 / 10000 multifunctional vacuum sintering furnace for sintering. The vacuum drying oven needs to be paused for 5 minutes every 30 minutes to prevent the machine from overheating.

[0056] The first stage - vacuum hot pressing sintering: put the composite powder E into a multifunctional vacuum sintering furnace and evacuate the vacuum to a vacuum degree of ≤5×10 -3 Pa, the temperature was raised from room temperature to 1500℃ at a heating rate of 10℃ / min, and sintered at 1500℃ and 34MPa sintering pressure for 30min. After vacuum hot pressing, the temperature was lowered to 1410℃ at a cooling rate of 5℃ / min. Vacuum densification (1500℃) was performed, and the liquid phase of HEA was formed, which was filled with Ti(C 0.7 ,N 0.3 ) and the gaps between TiB2 particles, making the metal ceramics more dense.

[0057] The second stage - carburizing treatment: first fill the furnace with high-purity nitrogen at a pressure of 0.3MPa; then introduce a mixture of CH4 and H2 with a volume ratio of 1:1 at a pressure of 0.04MPa, and keep it at 1410℃ for 20min;

[0058] By introducing the carburizing gradient structure design concept in the preparation process of self-lubricating titanium-based cermets, combined with specific raw material ratios and preparation processes, the prepared titanium-based cermets form a carburizing gradient structure in different areas, thereby further improving the mechanical properties of the material while maintaining good self-lubricating properties.

[0059] Carburizing gradient formation (1410℃ / CH4-H2): The active carbon atoms [C] decomposed by CH4 diffuse rapidly through the liquid phase Ni (diffusion coefficient 10 -11 m 2 / s), a TiC-rich layer is generated on the surface of the metal ceramic, and the surface metal phase migrates inward. Due to the existence of the carburized gradient structure, the gradient structure of the bonding phase of the chromium-rich cobalt-nickel alloy is retained in the core.

[0060] The third stage - nitrogen protection cooling: after the end of the 1410℃ holding temperature, switch to high-purity nitrogen atmosphere with a pressure of 0.3MPa; cool down from 1410℃ to 1000℃ at a cooling rate of 5℃ / min; then cool down from 1000℃ to 600℃ at a cooling rate of 3℃ / min; cool down with the furnace below 600℃;

[0061] Nitrogen protective cooling can inhibit the oxidation of h-BN to B2O3 and N2, thereby retaining lubricity.

[0062] After the above three steps of sintering, titanium-based metal ceramic A is obtained;

[0063] 3) Hot isostatic pressing

[0064] Using a QIH-15 hot isostatic pressing testing machine, titanium-based metal ceramic A was subjected to hot isostatic pressing treatment at a temperature of 1100°C, a pressure of 150 MPa, and an atmosphere of high-purity argon for 1 hour to obtain titanium-based metal ceramic B.

[0065] 4) Post-processing

[0066] The titanium-based cermet B was surface ground using a 200# diamond grinding wheel with a single feed rate of 0.02 mm / pass, ultimately obtaining the self-lubricating titanium-based cermet.

[0067] Preferably, the mass ratio of composite powder A to anhydrous ethanol is 1:2.

[0068] Compared with the prior art, the present invention has the following beneficial effects:

[0069] 1. Friction coefficient optimization

[0070] By modifying with KH-550 silane coupling agent, h-BN is oriented so that the h-BN (0001) crystal plane is oriented parallel to the sliding direction, reducing the interlayer shear resistance.

[0071] Synergistic toughening and lubrication of carbon fiber / HEA: Fe generated by laser ablation 40 Ni 20 Co 20 Cr 20 The coating captures the wear debris and forms a composite transfer film of carbon fiber fragments-HEA oxide.

[0072] Therefore, the present invention has a smaller friction coefficient regardless of room temperature or high temperature conditions.

[0073] 2. Brittleness improvement (fracture toughness from 6 → 12.8 MPa·m 1 / 2 )

[0074] HEA fiber toughening:

[0075] When cracks appear in the matrix, the high-strength HEA fibers span both sides of the cracks and prevent the cracks from opening through interfacial shear force; at the nanoscale, the Fe-Ni-Co-Cr multi-principal element solid solution in the HEA induces lattice distortion, forcing the cracks to deflect; at the same time, if the cracks want to be expanded, the carbon fibers need to be pulled out, which consumes a lot of energy. Combined with the plastic deformation of the matrix, a multi-level energy consumption system is formed, achieving material toughening.

[0076] The cracks of high entropy alloy and carbon fiber are bridged, and HEA fiber (tensile strength 1.8GPa) undergoes plastic deformation when the cracks propagate, consuming fracture energy, which greatly improves the toughness of titanium-based cermets on a macro scale. 40 Ni 20 Co 20 Cr 20 The carbon fiber-wrapped composite structure not only leverages the high strength and modulus of carbon fiber, but also the high hardness and wear resistance of high-entropy alloys. Furthermore, the titanium-based cermet's inherently good thermal shock resistance further enhances the material's overall strength and wear resistance. This composite reinforcement design enables the material to perform exceptionally well under high-load, high-wear conditions.

[0077] The added binder phase undergoes phase transformation under stress induction, Fe 40 Ni 20 Co 20 Cr 20 Under stress, FCC→HCP martensite transformation is induced, which absorbs the impact energy, reduces the stress directly applied to the ceramic body, and reduces the strain of the metal ceramic.

[0078] Added carburizing gradient structure design, surface hard layer (TiC 0.7 N 0.3 ) and the ductile core (chromium-cobalt-nickel alloy) to avoid sudden stress changes.

[0079] The combination of the three achieves great results in improving brittleness, with fracture toughness increasing from 6 to 12.8 MPa·m 1 / 2 .

[0080] 3. High-temperature lubrication enhancement (800℃ friction coefficient from 0.8 to 0.19)

[0081] At room temperature, the slip of the (0001) crystal plane of h-BN forms a low shear strength interface with the graphitized transfer film of carbon fibers.

[0082] At 600℃, the oxidation of Co / Ni in HEA generates CoO / NiO, which has a layered structure and can provide high-temperature lubrication performance.

[0083] The doping of Y2O3 raises the initial oxidation temperature of h-BN from 500℃ to 750℃ (TG weight gain <3%). h-BN@KH550 can still maintain good lubrication effect at high temperature, reducing the friction and wear between parts and prolonging the service life of the equipment. By introducing h-BN powder modified by KH-550, the self-lubrication performance of the material can be improved. This self-lubrication enables the material to work normally without external lubricant, reducing maintenance costs.

[0084] At higher temperatures (800℃), Fe 40 Ni 20 Co 20 Cr 20 will selectively oxidize to form spinel (Fe,Ni)(Co,Cr)2O4, partially replacing the lubricating effect of h-BN.

[0085] Through physicochemical reactions at different temperatures, the lubrication performance of the present application is significantly enhanced, with the friction coefficient at 800℃ decreasing from 0.8 to 0.19.

[0086] In summary, through multi-scale collaborative design, the present application successfully develops a titanium-based cermet with high toughness, high hardness, and excellent self-lubrication properties at high temperatures. BRIEF DESCRIPTION OF DRAWINGS

[0087] Figure 1 The process flow chart for producing self-lubricating titanium-based cermet according to the present application is shown in the figure. DETAILED DESCRIPTION

[0088] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all.

[0089] The purity and manufacturers of each drug used in the experiment are shown in Table 1:

[0090] Table 1. Raw material drug information

[0091] Drug name purity Manufacturer <![CDATA[Ti(C 0.7 ,N 0.3 )]]> ≥99.8％ Qinhuangdao Nuogao New Materials Development Co., Ltd. TiB2 ≥99.5％ Forsman Technology (Beijing) Co., Ltd. KH-550 ≥99％ Shandong Fengpan New Materials Co., Ltd. h-BN ≥99％ Hubei Chengfeng Chemical Co., Ltd. <![CDATA[Y2O3]]> ≥99.9％ Shanghai Yaotian New Material Technology Co., Ltd. Polyacrylonitrile-based T700 grade carbon fiber ≥99％ Ningbo Pantai Chemical Co., Ltd. Fe(NO3)3.6H2O ≥99.7％ Shanghai MacLean Biochemical Technology Co., Ltd. <![CDATA[Ni(NO3)2·6H2O]]> ≥99.7％ Shanghai MacLean Biochemical Technology Co., Ltd. <![CDATA[Co(NO3)2·6H2O]]> ≥99.7％ Shanghai MacLean Biochemical Technology Co., Ltd. <![CDATA[Cr(NO3)3·6H20]]> ≥99.7％ Shanghai MacLean Biochemical Technology Co., Ltd. PVP ≥99.7％ Shanghai MacLean Biochemical Technology Co., Ltd.

[0092] Example 1:

[0093] A self-lubricating titanium-based cermet and a preparation method thereof, comprising the following steps:

[0094] Preparation of HEA fibers:

[0095] The carbon fiber used was 7.9g polyacrylonitrile-based T700 grade carbon fiber with a single filament diameter of 7 μm and a length of 50-100 μm.

[0096] The carbon fiber was ultrasonically cleaned with acetone three times for 15 minutes each time to remove the epoxy resin coating on the surface, and then immersed in a 68% by mass nitric acid solution at 100° C. for 120 minutes to activate the fiber surface, and then rinsed with deionized water until neutral, vacuum dried at 120° C. for 2 hours, and heat treated at 800° C. in an argon environment for 1 hour, and annealed to remove the surface amorphous carbon layer, thereby obtaining raw material A;

[0097] 34.71 g of ferric nitrate hexahydrate Fe(NO3)3·6H2O, 11.89 g of nickel nitrate hexahydrate Ni(NO3)2·6H2O, 11.85 g of cobalt nitrate hexahydrate Co(NO3)2·6H2O and 18.47 g of chromium nitrate hexahydrate Cr(NO3)3·6H2O were weighed and dissolved in 240 mL of deionized water. 0.6 g of polyvinylpyrrolidone PVP was added as a dispersant and magnetic stirring was carried out for 30 min to obtain a high entropy alloy Fe 40 Ni 20 Co 20 Cr 20 Precursor solution.

[0098] Raw material A is immersed in high entropy alloy Fe 40 Ni 20 Co 20 Cr 20 The precursor solution was ultrasonically dispersed for 15 minutes; the precursor was uniformly attached to the fiber surface by the pulling method at a speed of 2 mm / s; the precursor was dried at 80 ° C for 30 minutes; the raw material A with the precursor attached was placed on a quartz substrate and placed in a laser processing chamber; the vacuum was evacuated to 10 -3 Pa and then filled with high-purity argon gas.

[0099] After laser treatment, the mixture was naturally cooled under argon protection to obtain raw material B;

[0100] The raw material B was annealed in a tube furnace in an atmosphere of 5% H2 / 95% Ar mixed gas, heated to 800°C at a rate of 5°C / min, kept warm for 1 hour, and then cooled to room temperature at a rate of 3°C / min to obtain high entropy alloy wrapped carbon fiber, i.e., HEA fiber.

[0101] In the laser scanning ablation process, an Nd:YAG pulsed laser was used with the following equipment parameters: wavelength 1064 nm; pulse width 5 ns; repetition frequency 10 Hz; spot diameter 50 μm; scanning speed 50 mm / s;

[0102] Laser parameters are set to: energy density 3J / cm 2 ; Scanning times 3 times; Scanning interval 30μm.

[0103] The preparation of self-lubricating titanium-based cermets includes the following steps:

[0104] 1) Raw material preparation:

[0105] 60g of Ti(C 0.7 ,N 0.3 ) powder, 25g of TiB2 powder, and 3g of Y2O3 powder were mixed uniformly to obtain composite powder A;

[0106] 2) Ball milling and pressing:

[0107] After placing composite powder A into the tungsten carbide ball mill of the QM-3SP4 planetary ball mill, weigh grinding balls according to a ball-to-material ratio of 10:1 and place them into the ball mill. Dry milling is performed at a speed of 100 r / min for 5 h without adding liquid to obtain the dry-milled powder, i.e., composite powder B.

[0108] 18 g of HEA fiber and 2 g of h-BN@KH550 were added to composite powder B and pre-mixed by manual stirring for 5 min to obtain composite powder C;

[0109] After placing composite powder C into the tungsten carbide hard alloy ball mill of the QM-3SP4 planetary ball mill, weigh grinding balls at a ball-to-material ratio of 10:1, with tungsten carbide balls of Φ5 mm and Φ10 mm in a ratio of 1:1, and place them into the ball mill. Then, pour in anhydrous ethanol until the anhydrous ethanol just covers the powder, and wet grind at a speed of 150 r / min for 10 h to obtain composite powder D.

[0110] Pour the composite powder D into a stainless steel dish, place it in a DZF-6050 vacuum drying oven, dry it at 70°C for 12 hours, and then pass it through a 100-mesh sieve;

[0111] The dried composite powder D was placed in a stainless steel mold and pre-pressed using a hydraulic press at a pressure of 5 MPa for 5 minutes to obtain composite powder E.

[0112] 3) sintering forming

[0113] Sintering is performed by using a HIGH-MULTI-5000 / 10000 type multifunctional vacuum sintering furnace, and a vacuum drying oven needs to be paused for 5 minutes every 30 minutes of work to prevent the machine from overheating:

[0114] First stage - vacuum hot-pressing sintering: the composite powder E is placed in the multifunctional vacuum sintering furnace, vacuumized to a vacuum degree of ≤5×10 -3 Pa, heated from room temperature to 1500℃ at a heating rate of 10℃ / min, sintered at a sintering temperature of 1500℃ and a sintering pressure of 34 MPa, and the holding time is 30 min; after the vacuum hot-pressing sintering is completed, it is cooled to 1410℃ at a cooling rate of 5℃ / min;

[0115] Second stage - carburizing treatment: high-purity nitrogen is filled into the furnace, and the pressure is 0.3 MPa; the mixed gas of CH4 and H2 with a volume ratio of 1:1 is introduced, and the pressure is 0.04 MPa, and the holding time is 20 min at 1410℃;

[0116] Third stage - nitrogen protection cooling: after the holding at 1410℃ is completed, the atmosphere is switched to high-purity nitrogen, and the pressure is 0.3 MPa; cooled from 1410℃ to 1000℃ at a cooling rate of 5℃ / min; then cooled from 1000℃ to 600℃ at a cooling rate of 3℃ / min; cooled below 600℃ with the furnace;

[0117] After the above three steps of sintering, titanium-based cermet A is obtained;

[0118] 3) hot isostatic pressing treatment

[0119] The titanium-based cermet A is subjected to hot isostatic pressing treatment by using a QIH-15 type hot isostatic pressing experimental machine under the conditions of a temperature of 1100℃, a pressure of 150 MPa, and a high-purity argon atmosphere, and the time is 1h, to obtain titanium-based cermet B.

[0120] 4) post-treatment

[0121] The titanium-based cermet B is subjected to plane grinding by using a diamond grinding wheel with a particle size of 200#, and the feed amount is 0.02mm / pass, and finally the self-lubricating titanium-based cermet is obtained.

[0122] The mass ratio of the composite powder A to anhydrous ethanol is 1:2.

[0123] Different from Example 1, Examples 2-3 are designed and completed according to different formulations:

[0124] Example 2:

[0125] A self-lubricating titanium-based cermet and a preparation method thereof, comprising the following steps:

[0126] Preparation of HEA fibers:

[0127] The carbon fiber used was 6.5 g polyacrylonitrile-based T700 grade carbon fiber with a single filament diameter of 7 μm and a length of 50-100 μm.

[0128] The carbon fiber was ultrasonically cleaned with acetone three times for 15 minutes each time to remove the epoxy resin coating on the surface, and then immersed in a 68% by mass nitric acid solution at 100° C. for 120 minutes to activate the fiber surface, and then rinsed with deionized water until neutral, vacuum dried at 120° C. for 2 hours, and heat treated at 800° C. in an argon environment for 1 hour, and annealed to remove the surface amorphous carbon layer, thereby obtaining raw material A;

[0129] 28.96 g of ferric nitrate hexahydrate Fe(NO3)3·6H2O, 9.90 g of nickel nitrate hexahydrate Ni(NO3)2·6H2O, 9.89 g of cobalt nitrate hexahydrate Co(NO3)2·6H2O and 15.38 g of chromium nitrate hexahydrate Cr(NO3)3·6H2O were weighed and dissolved in 200 mL of deionized water. 0.5 g of polyvinylpyrrolidone PVP was added as a dispersant and magnetic stirring was carried out for 30 min to obtain a high entropy alloy Fe 40 Ni 20 Co 20 Cr 20 Precursor solution.

[0130] Raw material A is immersed in high entropy alloy Fe 40 Ni 20 Co 20 Cr 20 The precursor solution was ultrasonically dispersed for 15 minutes; the precursor was uniformly attached to the fiber surface by the pulling method at a speed of 2 mm / s; the precursor was dried at 80 ° C for 30 minutes; the raw material A with the precursor attached was placed on a quartz substrate and placed in a laser processing chamber; the vacuum was evacuated to 10 -3 Pa and then filled with high-purity argon gas.

[0131] The same laser scanning ablation process as in Example 1 was used, and after laser treatment, the raw material B was naturally cooled under argon protection.

[0132] The raw material B was annealed in an atmosphere of 5% H2 / 95% Ar mixed gas in a tubular furnace, heated to 800°C at a rate of 5°C / min, kept warm for 1 hour, and then cooled to room temperature at a rate of 3°C / min to obtain high entropy alloy wrapped carbon fiber, i.e., HEA fiber.

[0133] The preparation of self-lubricating titanium-based cermets includes the following steps:

[0134] 1) Raw material preparation:

[0135] 65g of Ti(C 0.7 ,N 0.3 ), 22.5g of TiB2 and 2g of Y2O3 powder were mixed evenly to obtain composite powder A;

[0136] 2) Ball milling and pressing:

[0137] After placing composite powder A into the tungsten carbide ball mill of the QM-3SP4 planetary ball mill, weigh grinding balls according to a ball-to-material ratio of 10:1 and place them into the ball mill. Dry milling is performed at a speed of 100 r / min for 5 h without adding liquid to obtain the dry-milled powder, i.e., composite powder B.

[0138] 15 g of HEA fiber and 1.5 g of h-BN@KH550 were added to composite powder B and pre-mixed by manual stirring for 5 min to obtain composite powder C.

[0139] After placing composite powder C into the tungsten carbide hard alloy ball mill of the QM-3SP4 planetary ball mill, weigh grinding balls at a ball-to-material ratio of 10:1, with tungsten carbide balls of Φ5 mm and Φ10 mm in a ratio of 1:1, and place them into the ball mill. Then, pour in anhydrous ethanol until the anhydrous ethanol just covers the powder, and wet grind at a speed of 150 r / min for 10 h to obtain composite powder D.

[0140] Pour the composite powder D into a stainless steel dish, place it in a DZF-6050 vacuum drying oven, dry it at 70°C for 12 hours, and then pass it through a 100-mesh sieve;

[0141] The dried composite powder D was placed in a stainless steel mold and pre-pressed using a hydraulic press at a pressure of 5 MPa for 5 minutes to obtain composite powder E.

[0142] 3) Sintering

[0143] A HIGH-MULTI-5000 / 10000 multifunctional vacuum sintering furnace was used to sinter the titanium-based cermet A using the same sintering procedure as in Example 1.

[0144] 3) Hot isostatic pressing

[0145] Using a QIH-15 hot isostatic pressing testing machine, titanium-based metal ceramic A was subjected to hot isostatic pressing treatment at a temperature of 1100°C, a pressure of 150 MPa, and an atmosphere of high-purity argon for 1 hour to obtain titanium-based metal ceramic B.

[0146] 4) Post-processing

[0147] The titanium-based cermet B was surface ground using a 200# diamond grinding wheel with a feed rate of 0.02 mm / pass, ultimately obtaining the self-lubricating titanium-based cermet.

[0148] Wherein, the mass ratio of composite powder A to anhydrous ethanol is 1:2.

[0149] Example 3:

[0150] A self-lubricating titanium-based cermet and a preparation method thereof, comprising the following steps:

[0151] Preparation of HEA fibers:

[0152] The carbon fiber used was 5.2 g of polyacrylonitrile-based T700 grade carbon fiber with a single filament diameter of 7 μm and a length of 50-100 μm.

[0153] The carbon fiber was ultrasonically cleaned with acetone three times for 15 minutes each time to remove the epoxy resin coating on the surface, and then immersed in a 68% by mass nitric acid solution at 100° C. for 120 minutes to activate the fiber surface, and then rinsed with deionized water until neutral, vacuum dried at 120° C. for 2 hours, and heat treated at 800° C. in an argon environment for 1 hour, and annealed to remove the surface amorphous carbon layer, thereby obtaining raw material A;

[0154] 23.17 g of ferric nitrate hexahydrate Fe(NO3)3·6H2O, 7.92 g of nickel nitrate hexahydrate Ni(NO3)2·6H2O, 7.91 g of cobalt nitrate hexahydrate Co(NO3)2·6H2O and 12.30 g of chromium nitrate hexahydrate Cr(NO3)3·6H2O were weighed and dissolved in 160 mL of deionized water. 0.4 g of polyvinylpyrrolidone PVP was added as a dispersant and magnetic stirring was carried out for 30 min to obtain a high entropy alloy Fe 40 Ni 20 Co 20 Cr 20 Precursor solution.

[0155] Raw material A is immersed in high entropy alloy Fe 40 Ni 20 Co 20 Cr 20 The precursor solution was ultrasonically dispersed for 15 minutes; the precursor was uniformly attached to the fiber surface by the pulling method at a speed of 2 mm / s; the precursor was dried at 80 ° C for 30 minutes; the raw material A with the precursor attached was placed on a quartz substrate and placed in a laser processing chamber; the vacuum was evacuated to 10 -3 Pa and then filled with high-purity argon gas.

[0156] The same laser scanning ablation process as in Example 1 was used, and after laser treatment, the raw material B was naturally cooled under argon protection.

[0157] The raw material B was annealed in an atmosphere of 5% H2 / 95% Ar mixed gas in a tubular furnace, heated to 800°C at a rate of 5°C / min, kept warm for 1 hour, and then cooled to room temperature at a rate of 3°C / min to obtain high entropy alloy wrapped carbon fiber, i.e., HEA fiber.

[0158] The preparation of self-lubricating titanium-based cermets includes the following steps:

[0159] 1) Raw material preparation:

[0160] 70g of Ti(C 0.7 ,N 0.3 ) powder, 20g of TiB2 powder, and 1g of Y2O3 powder were mixed uniformly to obtain composite powder A;

[0161] 2) Ball milling and pressing:

[0162] After placing composite powder A into the tungsten carbide ball mill of the QM-3SP4 planetary ball mill, weigh grinding balls according to a ball-to-material ratio of 10:1 and place them into the ball mill. Dry milling is performed at a speed of 100 r / min for 5 h without adding liquid to obtain the dry-milled powder, i.e., composite powder B.

[0163] 12 g of HEA fiber and 1 g of h-BN@KH550 were added to composite powder B and pre-mixed by manual stirring for 5 min to obtain composite powder C.

[0164] After placing composite powder C into the tungsten carbide hard alloy ball mill of the QM-3SP4 planetary ball mill, weigh grinding balls at a ball-to-material ratio of 10:1, with tungsten carbide balls of Φ5 mm and Φ10 mm in a ratio of 1:1, and place them into the ball mill. Then, pour in anhydrous ethanol until the anhydrous ethanol just covers the powder, and wet grind at a speed of 150 r / min for 10 h to obtain composite powder D.

[0165] Pour the composite powder D into a stainless steel dish, place it in a DZF-6050 vacuum drying oven, dry it at 70°C for 12 hours, and then pass it through a 100-mesh sieve;

[0166] The dried composite powder D was placed in a stainless steel mold and pre-pressed using a hydraulic press at a pressure of 5 MPa for 5 minutes to obtain composite powder E.

[0167] 3) Sintering

[0168] The titanium-based cermet A was obtained by sintering in a HIGH-MULTI-5000 / 10000 multifunctional vacuum sintering furnace using the same sintering procedure as in Example 1.

[0169] 3) Hot isostatic pressing

[0170] Using a QIH-15 hot isostatic pressing testing machine, titanium-based metal ceramic A was subjected to hot isostatic pressing treatment at a temperature of 1100°C, a pressure of 150 MPa, and an atmosphere of high-purity argon for 1 hour to obtain titanium-based metal ceramic B.

[0171] 4) Post-processing

[0172] The titanium-based cermet B was surface ground using a 200# diamond grinding wheel with a feed rate of 0.02 mm / pass, ultimately obtaining the self-lubricating titanium-based cermet.

[0173] Wherein, the mass ratio of composite powder A to anhydrous ethanol is 1:2.

[0174] Also designed accordingly:

[0175] Comparative Example 1: The formula and experimental method are the same as those in Example 2, but with the addition of excess Fe 40 Ni 20 Co 20 Cr 20 ;

[0176] Comparative Example 2: The formula and experimental method are the same as those in Example 2, but without adding Fe 40 Ni 20 Co 20 Cr 20 ;

[0177] Comparative Example 3: The formula and experimental method are the same as those in Example 2, but an excess amount of carbon fiber is added;

[0178] Comparative Example 4: The formula and experimental method are the same as those of Example 2, but without adding carbon fiber;

[0179] Comparative Example 5: The formula and experimental method are the same as those in Example 2, but an excess of Ti(C 0.7 ,N 0.3 )powder;

[0180] Comparative Example 6: The formula and experimental method are the same as those in Example 2, but without adding Ti(C 0.7 ,N 0.3 )powder;

[0181] Comparative Example 7: The formula and experimental method are the same as those in Example 2, but an excess of TiB2 powder is added;

[0182] Comparative Example 8: The formulation and experimental method are the same as those in Example 2, but without adding TiB2 powder;

[0183] Comparative Example 9: The formulation and experimental method are the same as those of Example 2, but an excess of h-BN powder is added;

[0184] Comparative Example 10: The formulation and experimental method are the same as those of Example 2, but without adding h-BN powder;

[0185] Comparative Example 11: The formula and experimental method are the same as those in Example 2, but an excess of Y2O3 powder is added;

[0186] Comparative Example 12: The formulation and experimental method are the same as those in Example 2, but without adding Y2O3 powder;

[0187] Comparative Example 13: The formulation is the same as that of Example 2, but laser scanning ablation is not performed;

[0188] Comparative Example 14: The same formulation as Example 2, but without pre-pressing;

[0189] Comparative Example 15: The formulation is the same as that of Example 2, but without hot isostatic pressing;

[0190] The specific formula and test method are shown in Table 2:

[0191] Table 2. Formula and production process of titanium-based cermets

[0192]

[0193] According to the plan, the porosity (%), hardness (HRA), density (g / cm 3 ), thermal expansion coefficient (×10 -6 / K), flexural strength (MPa), fracture toughness (MPa·m 1 / 2 ), compression strength (MPa), elastic modulus (GPa), friction coefficient (room temperature / 800℃), wear rate (×

[0194] 10 -6 mm 3 / N·m), and the limit PV value (MPa·m / s) are used for specific performance testing, and the corresponding test results are shown below:

[0195] 1. Porosity (%) and density

[0196] Test method: Archimedes drainage method (ASTM C373)

[0197] Use an electronic balance with an accuracy of 0.001g to weigh the mass M1 of the dry sample. Use a thin wire or clamp to suspend the sample and immerse it completely in water, ensuring that the sample does not touch the wall of the container. Soak and boil in water for 2 hours to obtain the saturated mass M2. Use a balance to measure the mass of the sample in water (wet state) to obtain the mass of the sample suspended in water M3;

[0198]

[0199] where ρwater is the density of water (usually 1 g / cm3 or 1000 kg / m 3 ).

[0200]

[0201] 2. Hardness (HRA)

[0202] Test Method: Rockwell Hardness A Scale (ASTM E18)

[0203] Test surface must be polished to Ra < 0.2 pm, initial test force 10 kgf, indenter diamond cone. Main test force 50 kgf for 15 s, residual indentation depth measured after removal, measured using a Wilson Rockwell type Rockwell Hardness tester, average of 5 points.

[0204] 3. Coefficient of Thermal Expansion (x 10 -6 / K)

[0205] Test Method: Thermomechanical Analysis (TMA, ASTM E831)

[0206] Using a Netzsch TMA 402 TMA instrument, heat the sample to 1000 °C at a rate of 5 °C / min, record the change in length (AL), the coefficient of thermal expansion is AL / L0.

[0207] 4. Flexural Strength (MPa)

[0208] Test Method: Three Point Bending Test (ASTM C1161)

[0209] Sample size: 3 mm x 4 mm x 40 mm, span 30 mm.

[0210] Using an Instron 5967 universal testing machine, determine the breaking load of the material, then its flexural strength s b is:

[0211]

[0212] (F: breaking load, L: span, b: width, h: height)

[0213] 5. Fracture Toughness (MPa m 1 / 2 )

[0214] Test Method: Single Edge Notched Beam (SENB, ASTM E399)

[0215] Sample: 5 mm x 10 mm x 50 mm, pre-notched (depth 2.5 mm).

[0216] The fracture load of the material was measured using an Instron 5967 universal testing machine, and its fracture toughness K IC for

[0217]

[0218] (a: notch depth, W: specimen height, f: geometric correction factor)

[0219] 6. Elastic modulus (GPa)

[0220] Test method: Pulse excitation method (ASTM E1876)

[0221] The elastic modulus was calculated using a Grindo-Sonic elastic modulus tester based on the measured natural frequency of the specimen.

[0222] 7. Friction coefficient (room temperature / 800℃)

[0223] Test method: Ball-disc friction test (ASTM G99)

[0224] The ball-on-disk friction test was conducted using a CSM Tribometer friction and wear tester in an Ar inert atmosphere with a load of 10 N and a rotation speed of 200 r / min using SiC (Φ6 mm) grinding balls.

[0225] 8. Wear rate (×10 -6 mm 3 / N·m)

[0226] Test method: Volume loss method (ISO 20808)

[0227] The wear scar cross section was measured using a Bruker ContourGT surface profilometer.

[0228]

[0229] (V: wear volume, F: load, S: sliding distance)

[0230] 9.Limit PV value (MPa·m / s)

[0231] Test method: Step load friction test (ASTM G133)

[0232] A TE77 high-speed friction tester was used to maintain a constant sliding speed and gradually increase the load until failure.

[0233] Limit PV value = maximum pressure before failure (P) × speed (V).

[0234] The performance test data are summarized and plotted into Table 3:

[0235] Table 3. Performance test data of titanium-based cermets

[0236]

[0237] Data analysis shows that:

[0238] The addition of HEA fiber has a significant effect on the flexural strength, fracture toughness and wear rate of the product. In Example 2, when the HEA content is 10g, the flexural strength of the product reaches 2421MPa and the fracture toughness reaches 12.8MPa·m 1 / 2 , the wear rate is only

[0239] 1.8×10 -6 mm 3 / N·m.

[0240] HEA fibers significantly improve the toughness of the material through crack bridging and plastic deformation effects. At the same time, the presence of HEA also optimizes the interface bonding, making the porosity of the product in Example 2 only 1.7%. However, compared with Comparative Example 1, when the HEA content is increased to 15g, the flexural strength is 1949MPa, a decrease of 19.5%, and the fracture toughness is 10.2MPa·m 1 / 2 , decreased by 20.3%, and the porosity increased to 2.1%. This is because the excessive amount of HEA fibers destroyed the continuity of the matrix and increased the interface defects.

[0241] Compared with comparative example 2, when there is no fiber toughening, the flexural strength of the product is 1843 MPa, which is a decrease of 23.9%, and the wear rate is 5.0×10 -6 mm 3 / N·m, an increase of 177.8%. Therefore, the addition amount of HEA fiber is reasonable within 10-12g (10-12wt%), and excessive or insufficient addition will result in loss of product performance.

[0242] The carbon fiber content has a significant effect on the friction coefficient and the ultimate PV value. In Example 2, when the carbon fiber content is 5g, the friction coefficient is 0.15 at room temperature and 0.19 at 800℃, and the ultimate PV value is 50MPa·m / s. At this time, the carbon fiber and h-BN form a continuous transfer film, showing excellent high-temperature lubricity. However, by comparing with Comparative Example 3, when the carbon fiber content is increased to 10g, the friction coefficient at room temperature is 0.41, an increase of 26.7%, and the wear rate is 6.5×10 -6 mm 3 / N·m, an increase of 38.9%. At this time, the carbon fibers in the metal ceramic are unevenly dispersed, the friction film formed is discontinuous, and the product performance is reduced.

[0243] In Comparative Example 4, which does not contain carbon fiber, the friction coefficient increased by 153.3% and the limiting PV value decreased by 56%. Therefore, it can be seen that carbon fiber needs to work synergistically with h-BN (5-6g, 5-6wt%), and increasing or decreasing either one will deteriorate the friction performance.

[0244] Ti(C 0.7 ,N 0.3 ) and TiB2 have a significant effect on hardness and thermal expansion coefficient. In Example 2, when Ti(C 0.7 ,N 0.3 ) and TiB2 is 65:22.5 (about 3:1), the hardness is 93HRA, and the thermal expansion coefficient is 7.0×10 -6 / K, the high hardness and low thermal expansion of the metal ceramic are achieved. However, in Comparative Example 5, Ti(C 0.7 ,N 0.3 ) content increased to 80g, the hardness increased to 94HRA, but the brittleness increased and the bending strength decreased to 1915MPa. 0.7 ,N 0.3 ) in Comparative Example 6, the hardness decreased by 35.5% and the thermal expansion coefficient increased by 35.7%. In Comparative Example 7, when the TiB2 content was increased to 40g, the fracture toughness decreased to 8.8MPa·m due to the increase in brittleness caused by excessive TiB2. 1 / 2 Therefore, Ti(C 0.7 ,N 0.3 When the ratio of ) to TiB2 is about 3:1, the comprehensive performance of the obtained product is optimal.

[0245] The synergistic effect of h-BN and Y2O3 has a significant impact on friction coefficient and porosity. In Example 2, when the h-BN content is 1.5g and the Y2O3 content is 2g, the friction coefficient is 0.15 at room temperature and the porosity is only 1.7%. In this system, h-BN provides directional lubrication for the product, while Y2O3 helps refine grain boundaries.

[0246] In Comparative Example 9, increasing the h-BN content to 5g reduced the friction coefficient to 0.18, but the fracture toughness decreased by 25.9%. In Comparative Example 10, without h-BN, the friction coefficient increased by 33.3% and the wear rate by 288.9%. In Comparative Example 12, without Y2O3, the porosity increased to 3.2%, while the fracture toughness decreased by 25.8%. Therefore, the synergistic effect of appropriate h-BN and Y2O3 content can optimize the product's lubricity and toughness.

[0247] Key processes such as laser scanning ablation, pre-pressing, and hot isostatic pressing also have a significant impact on the performance of the material. Compared with Example 2, in Comparative Example 13, the flexural strength without laser ablation decreased by 31.5% and the porosity increased by 135.3%. This is because the carbon fiber at this time failed to effectively adhere to the high entropy alloy and was not as good as the Ti(C) 0.7 ,N 0.3 ) poor bonding with the matrix and excessive interface defects. In Comparative Example 14, the flexural strength without preloading decreased by 18.8%, while the porosity increased by 170.6%. This is due to the low green density and insufficient densification effect produced by sintering. In Comparative Example 15, the flexural strength without HIP decreased by 37.2%, while the porosity increased by 200.0%. This is due to the high residual porosity, which makes cracks easily propagate along defects. Therefore, laser ablation, preloading, and hot isostatic pressing are essential processes in this process to ensure low porosity (<2%) and high strength.

[0248] The comparison of comprehensive properties shows that Example 2 has the best comprehensive properties, achieving a balance between toughness, lubricity and wear resistance.

[0249] Using Example 2 as a template, the test was repeated according to different carburizing times, and the hardness, flexural strength, and fracture toughness of the products were tested. Table 4 is plotted:

[0250] Table 4. Effect of different carburizing times on product properties

[0251]

[0252] Effect of carburizing time on material properties:

[0253] The experiment studied the effect of different carburizing times on the hardness, flexural strength, and fracture toughness of the material. The data correspond to different carburizing times: 0 minutes, 15 minutes, 20 minutes, and ≥25 minutes.

[0254] Without carburizing, the material hardness is 88.5HRA, bending strength is 1850MPa, and fracture toughness is 11.2MPa·m 1 / 2 At this point the material is homogeneous, with both hardness and strength at their lowest levels.

[0255] When the carburizing time is 15 minutes, the hardness of the material increases to 93.8HRA, the flexural strength increases to 2250MPa, and the fracture toughness increases to 12.8MPa·m 1 / 2 At this time, the carburizing time is in the optimal window, the thickness of the gradient layer formed is between 35-50μm, and the hard phase and the bonding phase reach a balanced state.

[0256] When the carburizing time is 20 minutes, the hardness of the material is slightly increased to 94.0HRA, the bending strength reaches 2300MPa, but the fracture toughness is slightly decreased to 12.5MPa·m 1 / 2 At this time, the strength of the material reaches the highest value, and the toughness slightly decreases due to the slight migration of Ni / Co elements.

[0257] When the carburizing time is greater than or equal to 25 minutes, the hardness, bending strength and fracture toughness of the material begin to decrease, because the carburizing time is too long, which leads to graphitization of the material and Ni depletion in the core.

[0258] Through experiments, it is found that the optimal carburizing time is 15-20 minutes, and in this time period, the hardness (≥93.8HRA) and strength (≥2250MPa) of the material reach the best state.

[0259] In summary, the present application is a high-performance carburized gradient structure self-lubricating titanium-based metal ceramic, which realizes three breakthrough performance characteristics through innovative design:

[0260] Ultra-low friction and wear resistance: the synergistic lubrication system of h-BN powder and HEA fiber is adopted, the room temperature friction coefficient is as low as 0.15, the high temperature friction coefficient is 0.19, and the wear rate is only 1.8*10 -6 mm 3 / N·m, which greatly improves the service life of the metal ceramic;

[0261] High strength and high toughness integration: HEA fiber toughening and gradient carburizing process are combined to greatly enhance the bending strength and fracture toughness;

[0262] Extreme working condition adaptability: at 800℃, a lubricating layer is formed by in-situ oxidation of HEA, the friction coefficient is kept at 0.19, and the wear rate is reduced by 79% compared with traditional materials.

[0263] Its comprehensive performance exceeds that of conventional titanium-based metal ceramics, and it has the characteristics of high hardness, low thermal expansion coefficient and high temperature self-lubrication, which can meet the high-end demands of aero-engine components and ultra-high speed cutting tools, and is an ideal choice for the new generation of wear-resistant and friction-reducing materials.

[0264] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any skilled person in the art can make equivalent replacement or change according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A self-lubricating titanium-based cermet, characterized in that: The invention comprises the following raw materials in parts by weight: 60-70 parts of Ti(C 0.7 ,N 0.3 )powder; 20-25 parts of TiB2 powder; 12-18 parts of HEA fiber, which is wrapped with high entropy alloy Fe 40 Ni 20 Co 20 Cr 20 of carbon fiber; 1-2 parts of h-BN@KH550, i.e., h-BN modified with KH550; 1-3 parts of Y2O3 powder; The preparation method of the HEA fiber comprises the following steps: S1. Raw material preparation The carbon fiber is polyacrylonitrile-based T700 grade carbon fiber with a single filament diameter of 7 μm and a length of 50-100 μm; The carbon fiber was ultrasonically cleaned with acetone three times for 15 minutes each time to remove the epoxy resin coating on the surface, and then immersed in a 68% by mass nitric acid solution at 100° C. for 120 minutes to activate the fiber surface, and then rinsed with deionized water until neutral, vacuum dried at 120° C. for 2 hours, and heat treated at 800° C. in an argon environment for 1 hour, and annealed to remove the surface amorphous carbon layer, thereby obtaining raw material A; S2. Laser scanning ablation process Raw material A is immersed in high entropy alloy Fe 40 Ni 20 Co 20 Cr 20 The precursor solution was ultrasonically dispersed for 15 min; the precursor was evenly attached to the fiber surface using the Czochralski method at a speed of 2 mm / s; Dry at 80℃ for 30min; Place the precursor attached raw material A on a quartz substrate and place it in the laser processing chamber; Vacuum to 10 -3 Pa is then filled with high-purity argon gas; After laser treatment, the mixture was naturally cooled under argon protection to obtain raw material B; S3, HEA fiber post-treatment The raw material B was annealed in an atmosphere of 5% H2 / 95% Ar mixed gas in a tubular furnace, heated to 800°C at a rate of 5°C / min, kept warm for 1 hour, and then cooled to room temperature at a rate of 3°C / min to obtain carbon fiber wrapped with high entropy alloy, namely HEA fiber.

2. The self-lubricating titanium-based cermet according to claim 1, characterized in that: In the laser scanning ablation process, an Nd:YAG pulse laser is used, and the equipment parameters are as follows: wavelength 1064nm; pulse width 5ns; repetition frequency 10Hz; spot diameter 50μm; scanning speed 50mm / s; Laser parameters are set to: energy density 3J / cm 2 ; Scanning times 3 times; Scanning interval 30μm.

3. The self-lubricating titanium-based cermet according to claim 1, characterized in that: The preparation method of h-BN@KH550 comprises the following steps: Sodium hydroxide and deionized water were added to a round-bottom flask and stirred to dissolve. Hexagonal boron nitride (h-BN) powder was then added and refluxed at 120°C for 24 hours. After filtration, washing twice with water, and drying, h-BN powder with surface hydroxyl activated, i.e., h-BN@OH, was obtained. Anhydrous ethanol and 3-aminopropyltriethoxysilane KH-550 were added to a beaker, the pH was adjusted to 3-5 with acetic acid and hydrolyzed for 30 minutes to obtain a mixed solution, which was then added to a round-bottom flask containing h-BN@OH and refluxed at 80°C for 4 hours. After the reaction, the product was filtered, washed with anhydrous ethanol and dried in an oven at 110 °C for 12 h to obtain KH-550 modified h-BN powder, i.e. h-BN@KH550.

4. The self-lubricating titanium-based cermet according to claim 1, characterized in that: The high entropy alloy Fe 40 Ni 20 Co 20 Cr 20 The preparation process of the precursor solution is: 23.17-34.75 parts of ferric nitrate hexahydrate, 7.92-11.88 parts of nickel nitrate hexahydrate, 7.91-11.87 parts of cobalt nitrate hexahydrate and 12.30-18.46 parts of chromium nitrate hexahydrate were weighed and dissolved in 160-240 parts of deionized water, 0.4-0.6 parts of polyvinyl pyrrolidone was added as a dispersant, and magnetic stirring was carried out for 30 minutes to obtain a high entropy alloy Fe 40 Ni 20 Co 20 Cr 20 Precursor solution.

5. The self-lubricating titanium-based cermet according to claim 1, characterized in that: The high entropy alloy Fe 40 Ni 20 Co 20 Cr 20 The mass ratio with raw material A is 2:

1.

6. The method for preparing h-BN@KH550 according to claim 3, wherein: The mass ratio of sodium hydroxide, deionized water and hexagonal boron nitride is 2:10:1; the mass ratio of anhydrous ethanol and 3-aminopropyltriethoxysilane is 20:1; and the mass ratio of the mixed solution and h-BN@OH is 21:

1.

7. The method for preparing the self-lubricating titanium-based cermet according to any one of claims 1 to 5, characterized in that: The steps include: 1) Raw material preparation: Ti(C 0.7 ,N 0.3 ) powder, TiB2 powder, and Y2O3 powder are uniformly mixed to obtain composite powder A; 2) Ball milling and pressing: After placing composite powder A into the tungsten carbide ball mill of the QM-3SP4 planetary ball mill, weigh grinding balls according to a ball-to-material ratio of 10:1 and place them into the ball mill. Dry milling is performed at a speed of 100 r / min for 5 h without adding liquid to obtain the dry-milled powder, i.e., composite powder B. HEA fiber and h-BN@KH550 were added to composite powder B and pre-mixed manually for 5 min to obtain composite powder C. After placing composite powder C into the tungsten carbide hard alloy ball mill of the QM-3SP4 planetary ball mill, weigh grinding balls at a ball-to-material ratio of 10:1, with tungsten carbide balls of Φ5 mm and Φ10 mm in a ratio of 1:1, and place them into the ball mill. Then, pour in anhydrous ethanol until the anhydrous ethanol just covers the powder, and wet grind at a speed of 150 r / min for 10 h to obtain composite powder D. Pour the composite powder D into a stainless steel dish, place it in a DZF-6050 vacuum drying oven, dry it at 70°C for 12 hours, and then pass it through a 100-mesh sieve; The dried composite powder D was placed in a stainless steel mold and pre-pressed using a hydraulic press at a pressure of 5 MPa for 5 minutes to obtain composite powder E. 3) Sintering Use HIGH-MULTI-5000 / 10000 multifunctional vacuum sintering furnace for sintering. The vacuum drying oven needs to be paused for 5 minutes every 30 minutes to prevent the machine from overheating. The first stage - vacuum hot pressing sintering: put the composite powder E into a multifunctional vacuum sintering furnace and evacuate the vacuum to a vacuum degree of ≤5×10 -3 Pa, heating from room temperature to 1500℃ at a heating rate of 10℃ / min, sintering at 1500℃ and 34MPa sintering pressure, holding time for 30min; after vacuum hot pressing sintering, cooling down to 1410℃ at a cooling rate of 5℃ / min; The second stage - carburizing treatment: high-purity nitrogen is filled into the furnace at a pressure of 0.3MPa; a mixture of CH4 and H2 with a volume ratio of 1:1 is introduced at a pressure of 0.04MPa and the temperature is kept at 1410℃ for 20min; The third stage - nitrogen protection cooling: after the end of the 1410℃ holding period, switch to high-purity nitrogen atmosphere with a pressure of 0.3MPa; cool down from 1410℃ to 1000℃ at a cooling rate of 5℃ / min; then cool down from 1000℃ to 600℃ at a cooling rate of 3℃ / min; cool down with the furnace below 600℃; After the above three steps of sintering, titanium-based metal ceramic A is obtained; 3) Hot isostatic pressing Using a QIH-15 hot isostatic pressing machine, titanium-based cermet A was hot isostatically pressed for 1 h at a temperature of 1100°C, a pressure of 150 MPa, and an atmosphere of high-purity argon to obtain titanium-based cermet B. 4) Post-processing The titanium-based cermet B was surface ground using a 200# diamond grinding wheel with a feed rate of 0.02 mm / pass, and finally a self-lubricating titanium-based cermet was obtained.

8. The self-lubricating titanium-based cermet according to claim 7, characterized in that: In the above 2), the mass ratio of the composite powder C to anhydrous ethanol is 1:2.

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