Ultralow-friction high-temperature self-lubricating material

Abstract

The invention relates to an ultralow-friction high-temperature self-lubricating material which is composed of a WB4 phase and a beta-B phase which are prepared from 90-92.3% of B powder and 7.7-10% of W powder according to atomic percent, the friction coefficient of the ultralow-friction high-temperature self-lubricating material under the ultrahigh temperature condition of 1100 DEG C is smaller than or equal to 0.18, and the wear rate is 10 <-5 > mm < 3 > / Nm order of magnitude. According to the invention, molten B2O3 and layered WO3 are formed in situ in an ultrahigh-temperature environment, and a mixed lubrication mode of fluid lubrication and boundary lubrication is constructed on a friction interface, so that ultrahigh-temperature ultralow friction is realized. The technical requirement of low friction at extreme high temperature in modern industry is met, and a technical path is provided for the design and preparation technology of an ultrahigh-temperature lubricating material.

Description

Technical Field

[0001] This invention relates to the field of ultra-high temperature lubrication technology, and in particular to an ultra-low friction high temperature self-lubricating material. Background Technology

[0002] In the rapid iteration of strategic emerging industries such as aerospace, energy, and high-end equipment manufacturing, equipment reliability under extreme operating conditions has become a core bottleneck for technological breakthroughs. Among them, lubrication in ultra-high temperature environments is particularly critical. When the operating temperature of equipment exceeds 500℃ (or even reaches 1000℃), traditional lubrication technologies are completely ineffective, and it is necessary to rely on targeted ultra-high temperature lubrication solutions. The formation of this technological background is directly related to the upgrading of industrial needs, the limitations of traditional technologies, and the challenges of extreme operating conditions. The development of ultra-high temperature lubrication wear-resistant materials has become one of the core paths to break through the bottleneck of ultra-high temperature lubrication.

[0003] Boride ceramics are commonly used self-lubricating ceramics due to the formation of self-lubricating boric acid or boron oxide. At high temperatures, boron oxide transforms into a molten liquid, introducing a high-temperature glass lubrication or liquid lubrication mechanism, giving high-temperature borides excellent lubricity. Therefore, the high-temperature lubrication performance of borides is directly related to their oxidation resistance and surface oxide stability. For example, the friction coefficient of the B4C self-pair at 1000℃ is 0.08, with the lubrication mechanism being the formation and melting softening of amorphous boron oxide. SiC and TiB2 have high hardness and good chemical stability, and are widely used in wear-resistant materials for harsh high-temperature environments. The friction coefficient of the SiC / TiB2 friction pair is around 0.80 at 1000℃, decreasing to around 0.55 when the temperature increases to 1200℃. The friction coefficient of the MoAlB / Si3N4 friction pair is 0.93 at 1000℃, decreasing to 0.50 when the temperature rises to 1200℃. (The text abruptly ends here, likely due to an incomplete translation or missing information.) 14 -TiB2 exhibits a low coefficient of friction (0.12) at 800 °C, and its high-temperature lubrication mechanism is AlMgB. 14 High boron content in materials generates B2O3 lubricant. h -BN is a highly promising high-temperature solid lubricant. h -BN-Al2O3 materials exhibit a friction coefficient as low as 0.09 at 1000 °C, with the molten amorphous phase B2O3 acting as a binder. h -BN layers reduce friction.

[0004] To date, some research progress has been made in exploring high-temperature solid lubricant material systems, and related applications have been obtained. However, with the development of modern industry, high-temperature lubrication faces the challenges of designing and preparing ultra-high temperature lubricant materials under complex and extreme working conditions. In particular, there is a lack of systematic basic theory in ultra-high temperature tribology above 1000 ℃. Compared with liquid lubrication, it is imperative to improve the lubrication performance of high-temperature solid lubricant materials. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a high-performance, ultra-low friction, high-temperature self-lubricating material.

[0006] To address the aforementioned problems, the present invention provides an ultra-low friction high-temperature self-lubricating material, characterized in that: the material, by atomic percentage, is composed of a WB4 phase and a β-B phase prepared from 90-92.3% B powder and 7.7-10% W powder, exhibiting a friction coefficient ≤0.18 and a wear rate of 10% under ultra-high temperature conditions of 1100℃. -5 mm 3 On the order of Nm.

[0007] The material exhibits a friction coefficient ranging from 0.09 to 0.15 under ultra-high temperature conditions of 1100℃, and a wear rate of 10%. 4 ~10 5 mm 3 / Nm range.

[0008] The material is WB4-βB bulk material with a hardness range of 44 ± 3 GPa ~ 28 ± 1 GPa.

[0009] The preparation method of the ultra-low friction high temperature self-lubricating material as described above is characterized in that: 90~92.3% of B powder and 7.7~10% of W powder are ball-milled and mixed in a planetary high-energy ball mill by atomic percentage. The resulting mixed powder is sintered by spark plasma and then naturally cooled to room temperature to obtain WB4-βB bulk material.

[0010] The ball milling conditions are as follows: ball-to-material mass ratio of 4:1, rotation speed of 250 r / min, and mixing time of 4 h.

[0011] The conditions for the discharge plasma sintering are as follows: heating rate of 100 ℃ / min, vacuum degree of 15~20 Pa, sintering temperature of 1600~1800 ℃, sintering pressure of 30 MPa, sintering time of 16 min, and radial pressure of 30 MPa.

[0012] Compared with the prior art, the present invention has the following advantages: 1. In this invention, the WB4-βB material is composed of WB4 phase and β-B phase. Molten B2O3 and layered WO3 are formed in situ in an ultra-high temperature environment, and a mixed lubrication of fluid lubrication and boundary lubrication is constructed at the friction interface.

[0013] 2. The present invention is prepared by spark plasma sintering, and the resulting WB4-βB material has superhard mechanical properties.

[0014] 3. This invention improves the mechanical properties of WB4 by enhancing its microstructure, thereby increasing its hardness and thermal stability, and thus achieving ultra-high temperature lubrication. It has good application prospects in strategic emerging fields such as aerospace, energy, and high-end equipment manufacturing. Attached Figure Description

[0015] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0016] Figure 1 The friction morphology of WB4-βB material in Example 3 of this invention at different temperatures.

[0017] Figure 2 The friction morphology of the SiC friction pair material in Example 3 of the present invention at different temperatures is shown. Detailed Implementation

[0018] An ultra-low friction high-temperature self-lubricating material is composed of a WB4 phase and a β-B phase, prepared by atomic percentage from 90-92.3% boron powder and 7.7-10% tungsten powder. It exhibits a friction coefficient ≤0.18 under ultra-high temperature conditions of 1100℃ and a wear rate of 102. -5 mm 3 The coefficient of friction is on the order of Nm, preferably in the range of 0.09~0.15 under ultra-high temperature conditions of 1100℃, and the wear rate is in the range of 10. 4 ~10 5 mm 3 / Nm range.

[0019] The material is a WB4-βB bulk material with a hardness range of 44 ± 3 GPa ~ 28 ± 1 GPa.

[0020] Its preparation method: On an atomic percentage basis, 90–92.3% B powder and 7.7–10% W powder were ball-milled in a planetary high-energy ball mill at a ball-to-powder mass ratio of 4:1 (g / g), a rotation speed of 250 r / min, and a mixing time of 4 h. The resulting mixed powder was loaded into a graphite mold and sintered in a spark plasma sintering furnace (SPS) at a heating rate of 100 °C / min, a vacuum of 15–20 Pa, a sintering temperature of 1600–1800 °C, a sintering pressure of 30 MPa, a sintering time of 16 min, and a radial pressure of 30 MPa. After sintering, the powder was allowed to cool naturally to room temperature to obtain WB4-βB bulk material.

[0021] Example 1: Step 1, Mixing: A mixture of 90% boron powder and 10% boron powder (WB9) was prepared by uniformly mixing in a molar ratio to obtain a mixed powder. The tungsten powder had a purity greater than 99% and a particle size of 1 μm. The boron powder had a purity greater than 99% and a particle size of 1 μm.

[0022] Step 2, Loading: After attaching graphite paper to the inner wall of a cylindrical graphite mold, the mixed powder is loaded into the mold, and two layers of graphite paper are placed above and below the powder. The statically pressed filler mold is then placed in an SPS sintering furnace.

[0023] Step 3, sintering: The SPS sintering furnace was evacuated and the vacuum level was maintained at 10~15 Pa. The temperature was increased to 1600~1800 °C at a heating rate of 100 °C / min. Then, the furnace was sintered at 30 MPa for 2~10 min. After the holding period, the pressure was immediately released to 5 MPa and the furnace was allowed to cool naturally to room temperature to obtain WB4-βB blocks. Step 4, Sample preparation: Remove the graphite paper from the surface of the block, and then mechanically polish it using a diamond sand disc and diamond polishing paste. The surface roughness of the polished sample is 0.025 μm.

[0024] Step 5, Ultra-high temperature tribological testing method: The tribological properties of the WB4-βB / SiC friction pair were tested on a GF-1 ball-disc contact friction and wear testing machine. The WB4-βB sample size was Φ 25 mm × 3 mm, the diameter of the SiC paired ball was 6 mm, the indoor air humidity range was 20~40%, the applied load was 5 N, the sliding speed was 300 rev / min, the sliding time was 30 min, and the sliding stroke was 5 mm.

[0025] The tribological properties of WB4-βB were tested using SiC as the friction pair at different temperatures. The test results are shown in Table 1.

[0026] Table 1 High-temperature tribological properties of samples prepared by WB9 Example 2: Step 1, Mixing: The tungsten powder was mixed evenly with 91.7% B powder and 8.3% W (WB11) powder in a molar ratio to obtain a mixed powder; wherein the tungsten powder had a purity greater than 99% and a particle size of 1 μm; and the boron powder had a purity greater than 99% and a particle size of 1 μm.

[0027] Step 2, Loading: After attaching graphite paper to the inner wall of a cylindrical graphite mold, the mixed powder is loaded into the mold, and two layers of graphite paper are placed above and below the powder. The statically pressed filler mold is then placed in an SPS sintering furnace.

[0028] Step 3, sintering: The SPS sintering furnace was evacuated and the vacuum level was maintained at 10~15 Pa. The temperature was increased to 1600~1800 °C at a heating rate of 100 °C / min. Then, the furnace was sintered at 30 MPa for 2~10 min. After the holding period, the pressure was immediately released to 5 MPa and the furnace was allowed to cool naturally to room temperature to obtain WB4-βB blocks. Step 4, Sample preparation: Remove the graphite paper from the surface of the block, and then mechanically polish it using a diamond sand disc and diamond polishing paste. The surface roughness of the polished sample is 0.025 μm.

[0029] Step 5: The ultra-high temperature tribological testing method is the same as in Example 1.

[0030] The tribological properties of WB4-βB were tested using SiC as the friction pair at different temperatures. The test results are shown in Table 2.

[0031] Table 2 High-temperature tribological properties of samples prepared by WB11 Example 3: Step 1, Mixing: 92.3% of B powder and 7.7% of W powder (WB12) were mixed evenly in a molar ratio to obtain a mixed powder; wherein the tungsten powder had a purity greater than 99% and a particle size of 1 μm; and the boron powder had a purity greater than 99% and a particle size of 1 μm.

[0032] Step 2, Loading: After attaching graphite paper to the inner wall of a cylindrical graphite mold, the mixed powder is loaded into the mold, and two layers of graphite paper are placed above and below the powder. The statically pressed filler mold is then placed in an SPS sintering furnace.

[0033] Step 3, sintering: The SPS sintering furnace was evacuated and the vacuum level was maintained at 10~15 Pa. The temperature was increased to 1600~1800 °C at a heating rate of 100 °C / min. Then, the furnace was sintered at 30 MPa for 2~10 min. After the holding period, the pressure was immediately released to 5 MPa and the furnace was allowed to cool naturally to room temperature to obtain WB4-βB blocks. Step 4, Sample preparation: Remove the graphite paper from the surface of the block, and then mechanically polish it using a diamond sand disc and diamond polishing paste. The surface roughness of the polished sample is 0.025 μm.

[0034] Step 5: The ultra-high temperature tribological testing method is the same as in Example 1.

[0035] The tribological properties of WB4-βB were tested using SiC as the friction pair at different temperatures, and the results are shown in Table 3. At ultra-high temperatures, due to fluid lubrication, the friction pair material did not experience wear, such as... Figure 2 As shown.

[0036] Table 3 High-temperature tribological properties of samples prepared by WB12 Friction morphology at different temperatures, such as Figure 1 As shown. By Figure 1 It can be observed that at ultra-high temperatures, the plate-like WO3 particles are wetted by the liquid phase of B2O3, forming a "solid-liquid" composite structure at the interface. This reduces friction through interlayer shearing, thus achieving ultra-high temperature lubrication.

Claims

1. An ultra-low friction high temperature self-lubricating material, characterized in that: The material is made of 90-92.3% B powder and 7.7-10% W powder, and consists of WB4 phase and β-B phase in atomic percentage, and the friction coefficient is ≤0.18 and the wear rate is in the order of 10 -5 mm 3 / Nm under 1100℃ ultra-high temperature conditions.

2. An ultra-low friction high temperature self-lubricating material as claimed in claim 1, characterized in that: The material has a friction coefficient in the range of 0.09~0.15 and a wear rate in the range of 10 4 ~10 5 mm 3 / Nm under the condition of 1100℃ ultra-high temperature.

3. An ultra-low friction high temperature self-lubricating material according to claim 1 or 2, characterised in that: The material is WB4-betaB bulk material, and the hardness range is 44 ± 3GPa ~ 28 ± 1 GPa.

4. The preparation method of an ultra-low friction high-temperature self-lubricating material as described in claim 1, characterized in that: 90-92.3% of B powder and 7.7-10% of W powder are ball-mixed in a planetary high-energy ball mill in atomic percentage, and the obtained mixed powder is naturally cooled to room temperature after being sintered by spark plasma, thereby obtaining the WB4-betaB bulk material.

5. A method of producing an ultra-low friction high temperature self- lubricating material as claimed in claim 4, characterized in that: The ball-mixing condition is that the ball-to-material mass ratio is 4:1, the rotating speed is 250 r / min, and the mixing time is 4 h.

6. A method of producing an ultra-low friction high temperature self- lubricating material as claimed in claim 4, characterized in that: The spark plasma sintering condition is that the temperature rising rate is 100 DEG C / min, the vacuum degree is 15-20 Pa, the sintering temperature is 1600-1800 DEG C, the sintering pressure is 30 MPa, the sintering time is 16 min, and the radial pressure is 30 MPa.

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