Ysz ceramic-based self-lubricating composite material, preparation method and application thereof

Abstract

The application discloses a YSZ ceramic-based self-lubricating composite material and a preparation method and application thereof, and relates to the technical field of self-lubricating ceramic materials.The raw material of the composite material comprises YSZ, graphene and BN powder coated with SiO2; the mixed powder is sintered at 1250-1350 DEG C by using a discharge plasma sintering technology under the pressure of 30-50 MPa to obtain a block-shaped composite ceramic; and the sintered ceramic is subjected to tribological property testing at 25-500 DEG C.The YSZ ceramic has improved tribological property at 25-500 DEG C by adding the graphene and the BN powder coated with SiO2 in the YSZ.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of self-lubricating ceramic materials, in particular to a YSZ ceramic-based self-lubricating composite material and a preparation method and application thereof. BACKGROUND

[0002] Ceramic matrix composites are composed of one or more reinforcing materials, such as fibers, whiskers, carbon nanotubes, graphene, particles and a second polymer in the ceramic matrix and metal phase. Such composites generally have excellent strength and wear resistance, good fracture toughness, high temperature stability, excellent thermal shock resistance and functionality. However, in engines, about 4-15% of fuel energy is lost due to friction. Therefore, improving the tribological properties of ceramic matrix composites to make them widely used in aerospace, automotive, energy and power, electronics and electrical fields has become the focus of current research. Yttria-stabilized zirconia has excellent mechanical properties, thermal properties and chemical stability, such as high hardness and high strength, low thermal conductivity, and oxidation resistance and corrosion resistance. However, due to high friction and high wear, the tribological properties of yttria-stabilized zirconia (YSZ) ceramics are not ideal. Therefore, adding a lubricating phase to the YSZ matrix is a key step in reducing friction and wear. SUMMARY

[0003] The present application aims at the deficiencies in the above background art, and provides a YSZ ceramic-based self-lubricating composite material and a preparation method and application thereof. The method sintering the powder by using a discharge plasma technology, and using a low-voltage, high-current direct current pulse to act on the sintered sample through a pressure head, effectively inhibits grain growth and improves the comprehensive performance of the material.

[0004] The first object of the present application is to provide a YSZ ceramic-based self-lubricating composite material, which comprises YSZ, and graphene and SiO2-coated BN powder.

[0005] The SiO2-coated BN powder and graphene are interspersed in the spherical ZrO2 matrix, connecting the ZrO2 together; wherein the SiO2-coated BN powder is in a flaky core-shell structure with BN powder as the core and SiO2 as the shell.

[0006] Preferably, the mass ratio of the YSZ, graphene and SiO2-coated BN powder is 1:0.01-0.2:0.01-0.2.

[0007] Preferably, the YSZ is 7YSZ or 8YSZ.

[0008] Preferably, the SiO2-coated BN powder is prepared according to the following steps:

[0009] After the BN powder is uniformly dispersed in a mixed solution of anhydrous ethanol, NH4OH and deionized water, TEOS is added, and after the reaction for 6-12 hours, the reaction product is filtered, washed and dried to obtain the SiO2-coated BN powder.

[0010] Preferably, the volume ratio of the anhydrous ethanol, NH4OH and deionized water is 20:3:4.

[0011] The use amount ratio of the BN powder to TEOS is 3g:10mL.

[0012] The second object of the present application is to provide a preparation method of a YSZ ceramic-based self-lubricating composite material, comprising the following steps:

[0013] The YSZ, graphene and SiO2-coated BN powder are ground and mixed, and after passing through a 30-80 mesh screen, a mixed powder is obtained.

[0014] The mixed powder is placed in a mold, and in a spark plasma sintering furnace at 1250-1350℃ for 10-20 minutes to obtain the YSZ ceramic-based self-lubricating composite material.

[0015] Preferably, the grinding and mixing process comprises: the YSZ, graphene and SiO2-coated BN powder are placed in a ball milling device for ball milling, wherein anhydrous ethanol and stainless steel balls are used as the ball milling medium, the rotation speed is 200-300℃ / min, and the ball milling time is 1-2 hours.

[0016] Preferably, in the sintering process, the pressure of the spark plasma sintering is 30-50MPa, and the heating rate is 50-100℃ / min.

[0017] Preferably, the mold is a graphite mold.

[0018] The third object of the present application is to provide an application of the YSZ ceramic-based self-lubricating composite material in a friction material.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] The YSZ ceramic-based self-lubricating composite material, the preparation method and the application thereof provided by the present application can improve the tribological properties of YSZ because the silicon dioxide-coated boron nitride and graphene are added at the same time, and because the boron nitride is further oxidized to form a relatively soft silicate glass phase at high temperature, which cooperates with the inherent lubricating effect of the graphene to greatly improve the tribological properties of YSZ.

[0021] The present application sintering powder by discharge plasma technology, using low voltage, high current direct current pulse through the pressure head to the sintering sample, while reducing the sintering temperature and improving the density, the sintering time is also shortened, thereby effectively inhibiting the grain growth, improving the comprehensive performance of the material. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The surface of three samples (YSZ-5Gr15BN, YSZ-10Gr10BN, YSZ-15Gr5BN) after SPS sintering, sanding and polishing.

[0023] Figure 2 The SEM-EDS diagram of the surface of three samples (YSZ-5Gr15BN, YSZ-10Gr10BN, YSZ-15Gr5BN) after SPS sintering, sanding and polishing.

[0024] Figure 3 The XRD diagram of three ceramic materials (YSZ-5Gr15BN, YSZ-10Gr10BN, YSZ-15Gr5BN) after SPS sintering.

[0025] Figure 4 The friction coefficient curve of four ceramic materials (YSZ, YSZ-5Gr15BN, YSZ-10Gr10BN, YSZ-15Gr5BN) at different temperatures.

[0026] Figure 5 Comparison of average friction coefficients at different temperatures. DETAILED DESCRIPTION

[0027] In order for those skilled in the art to better understand the technical solutions of the present application and to implement them, the present application will be further described below in conjunction with specific embodiments and drawings, but the embodiments are not limiting to the present application.

[0028] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a YSZ ceramic-based self-lubricating composite material, which comprises YSZ, and graphene and SiO2-coated BN powder.

[0029] The SiO2-coated BN powder and graphene are interspersed in the spherical ZrO2 matrix, connecting the ZrO2 together; wherein the SiO2-coated BN powder is in a flaky core-shell structure with BN powder as the core and SiO2 as the shell.

[0030] The mass ratio of the YSZ, graphene and SiO2-coated BN powder is 1:0.01-0.2:0.01-0.2.

[0031] The YSZ is 7YSZ or 8YSZ.

[0032] The SiO2-coated BN powder is prepared according to the following steps:

[0033] After the BN powder is uniformly dispersed in a mixed solution of anhydrous ethanol, NH4OH and deionized water, TEOS is added, and after 6-12 hours of reaction, the reaction product is filtered, washed and dried to obtain the SiO2-coated BN powder (h-BN@SiO2).

[0034] The volume ratio of the anhydrous ethanol, NH4OH and deionized water is 20:3:4;

[0035] The amount ratio of the BN powder to TEOS is 3g:10mL.

[0036] In an embodiment, the preparation method of the h-BN@SiO2 powder is as follows:

[0037] 3g of BN powder is ultrasonically dispersed in a mixture of 200mL of anhydrous ethanol, 30mL of NH4OH and 40mL of deionized water, and then strong magnetic stirring is performed for 30min to obtain a uniform suspension. Then, 10mL of TEOS is slowly added, and continuous stirring is performed at room temperature for 6 hours. After the reaction, the product is vacuum filtered through a nylon membrane, and washed with ethanol and deionized water in sequence. Free SiO2 particles are repeatedly removed several times, and then vacuum drying is performed to obtain the SiO2-coated BN white powder.

[0038] The YSZ ceramic-based self-lubricating composite material provided by the application is based on a YSZ / graphene / h-BN@SiO2 composite ceramic material, and is mainly prepared by sintering a powder mixture of the preparation raw materials by using a spark plasma sintering method under a pressure of 30-50MPa. The introduced graphene can improve the lubricating performance of the material, and the in-situ generated carbide (ZrC) can improve the wear resistance of the material to a certain extent. The h-BN@SiO2 can improve the oxidation resistance of the material, and the Si-B-O glaze phase generated by high-temperature friction can improve the high-temperature tribological performance of the material.

[0039] The second aspect of the application provides a preparation method of a YSZ ceramic-based self-lubricating composite material, including the following steps:

[0040] The YSZ, graphene and SiO2-coated BN powder are ground and mixed, and after passing through a 30-80 mesh screen, a mixed powder is obtained;

[0041] The mixed powder is placed in a mold, and is sintered in a spark plasma sintering furnace at 1250-1350℃ for 10-20min to obtain the YSZ ceramic-based self-lubricating composite material.

[0042] The grinding mixing process comprises: putting YSZ, graphene and SiO2-coated BN powder into a ball milling device for ball milling, wherein anhydrous ethanol and stainless steel balls are used as the ball milling medium, the rotation speed is 200-300 r / min, and the ball milling time is 1-2 h.

[0043] In the sintering process, the pressure of the spark plasma sintering is 30-50 MPa, and the temperature rising rate is 50-100℃ / min.

[0044] The mold is a graphite mold.

[0045] In an embodiment, a YSZ / graphene / h-BN@SiO2 composite ceramic preparation method comprises the following steps:

[0046] 1) preparing a mixed powder of YSZ, graphene and h-BN@SiO2;

[0047] 2) sintering the mixed powder by using the spark plasma sintering method under a pressure of 30-50 MPa to obtain a ceramic block.

[0048] In step 1), the mixed powder preparation method is as follows:

[0049] 1.1) according to the mass fraction, 1 part of YSZ, 0.01-0.2 parts of graphene and 0.01-0.2 parts of SiO2-coated BN powder are weighed and put into a ball mill for ball milling to make the powder uniformly mixed;

[0050] 1.2) the ball-milled powder is dried at 40-60℃ for 6-8 h;

[0051] 1.3) the dried powder is passed through a 30-80 mesh sieve to obtain a mixed powder with uniform particle size.

[0052] In step 1.1), the ball milling device is a planetary ball mill, and anhydrous ethanol and stainless steel balls are used as the ball milling medium, and the rotation speed is 200-300 r / min, and the ball milling time is 1-2 h to make the powder uniformly mixed.

[0053] In step 2), the pressure of the spark plasma sintering is 30-50 MPa, the temperature is 1250-1350℃, the temperature rising rate is 50-100℃ / min, the holding time is 10-20 min, and finally a ceramic block is sintered.

[0054] Step 1) is completed in an argon atmosphere glove box to prevent oxidation.

[0055] The powder obtained after step 1) ball milling is dried in a vacuum drying box and stored.

[0056] The atmosphere in the spark plasma sintering furnace in step 2) is argon, so as to prevent oxidation in the process.

[0057] The purity of the h-BN@SiO2, YSZ and graphene powder in the examples of the present application is 98% to 99.99%, and the particle size is 1 to 50 microns.

[0058] The third aspect of the present application provides a YSZ ceramic-based self-lubricating composite material for use in a friction material.

[0059] It should be noted that the experimental methods used in the present application are conventional methods unless otherwise specified; the reagents and materials used are commercially available unless otherwise specified.

[0060] Example 1

[0061] A method for preparing a YSZ ceramic-based self-lubricating composite material, comprising the following steps:

[0062] The YSZ-based ceramic material is treated by the process, and the specific treatment method is as follows: YSZ, graphene and h-BN@SiO2 powder are weighed according to a mass ratio of 80:5:15, then placed in a stainless steel tank for ball milling, with a ball:powder:anhydrous ethanol volume ratio of 4:2:1, a ball milling time of 2 hours and a rotation speed of 250 r / min. The composite powder after ball milling is sintered at 1300℃ and 40MPa to obtain a ceramic sample YSZ-5Gr15BN. The polished ceramic sample is detected by an X-ray diffractometer (XRD, Bruker D8 ADVANCE, λ =1.5404 Å) and the phase is calibrated.

[0063] The XRD image of the YSZ-5Gr15BN ceramic is shown in Figure 3 The XRD detection result shows that each phase in the sample is detected, indicating that the YSZ-5Gr15BN ceramic is successfully prepared by SPS sintering, and the tribological performance is detected next.

[0064] The tribological performance detection method of the present application is as follows:

[0065] The prepared YSZ-5Gr15BN ceramic material is evaluated for its friction and wear performance by GF-1200 (Lanzhou Zhongke Kaixing Technology Development Co., Ltd.). The counter ball is an Al2O3 ball, the load is 10N, the frequency is 3Hz, the experimental temperature is 25℃ and 500℃ respectively, and the running time is 20min.

[0066] The friction coefficient of the YSZ-5Gr15BN ceramic material provided in Example 1 at 25℃ and 500℃ is 0.19 and 0.52 respectively. The friction coefficient curve is shown in Figure 4 (b).

[0067] Example 2

[0068] A preparation method of a YSZ ceramic-based self-lubricating composite material, comprising the following steps:

[0069] The YSZ-based ceramic material is subjected to the process, and the specific processing method is as follows: YSZ, graphene and h-BN@SiO2 powder are weighed according to a mass ratio of 80:10:10, and then are placed in a stainless steel jar for ball milling, with a ball:powder:anhydrous ethanol volume ratio of 4:2:1, a ball milling time of 2 hours and a rotating speed of 250 r / min. The composite powder after ball milling is sintered at 1300 DEG C and 40 MPa to obtain a ceramic sample YSZ-10Gr10BN. The polished ceramic sample is detected by an X-ray diffractometer (XRD, Bruker D8 ADVANCE, λ = 1.5404 Å), and the phase of the sample is calibrated.

[0070] The XRD image of the YSZ-10Gr10BN ceramic is as shown in Figure 3 The XRD detection result shows that each phase in the sample is detected, indicating that the YSZ-10Gr10BN ceramic is successfully prepared by SPS sintering, and the tribological performance of the ceramic is detected.

[0071] The tribological performance detection method of the present application is as follows:

[0072] The prepared YSZ-10Gr10BN ceramic material is evaluated for friction and wear performance by using GF-1200 (Lanzhou Zhongke Kaixing Technology Development Co., Ltd.). The counter ball is an Al2O3 ball, the load is 10 N, the frequency is 3 Hz, the experimental temperature is 25 DEG C and 500 DEG C respectively, and the running time is 20 min.

[0073] The friction coefficients of the YSZ-10Gr10BN ceramic material provided in Example 2 at 25 DEG C and 500 DEG C are 0.24 and 0.27 respectively. The friction coefficient curve is as shown in Figure 4 (c).

[0074] Example 3

[0075] A preparation method of a YSZ ceramic-based self-lubricating composite material, comprising the following steps:

[0076] YSZ-based ceramic material is treated by the process, and the specific treatment method is as follows: YSZ, graphene, h-BN@SiO2 powder is weighed according to the mass ratio of 80:15:5, and then placed in a stainless steel tank for ball milling, the ball: powder: anhydrous ethanol volume ratio is 4:2:1, the ball milling time is 2 hours, and the rotating speed is 250 r / min. The composite powder after ball milling is sintered at 1300 DEG C and 40 MPa to obtain a ceramic sample YSZ-15Gr5BN. The polished ceramic sample is detected by an X-ray diffractometer (XRD, Bruker D8 ADVANCE, λ =1.5404 Å), and the phase of the sample is calibrated.

[0077] The XRD image of the YSZ-15Gr5BN ceramic is shown in Figure 3 The XRD detection result shows that each phase in the sample is detected, which indicates that the YSZ-15Gr5BN ceramic is successfully prepared by SPS sintering, and the tribological performance is detected next.

[0078] The tribological performance detection method of the application is as follows:

[0079] The prepared YSZ-15Gr5BN ceramic material is evaluated by GF-1200 (Lanzhou Zhongke Kaixing Technology Development Co., Ltd.) for its friction and wear performance. The counter-ball is Al2O3 ball, the load is 10 N, the frequency is 3 Hz, the experimental temperature is 25 DEG C and 500 DEG C respectively, and the running time is 20 min.

[0080] The friction coefficient of the YSZ-15Gr5BN ceramic material provided in Example 3 at 25 DEG C and 500 DEG C is 0.16 and 0.09 respectively, and the friction coefficient curve is shown in Figure 4 (d).

[0081] Figure 4 The provided friction coefficient comparison shows that the friction coefficients of YSZ at 25 DEG C and 500 DEG C are 0.47 and 0.62 respectively. It is shown that the addition of graphene and SiO2-coated BN significantly improves the tribological performance of the YSZ ceramic material.

[0082] In order to illustrate the related performance of the composite material provided by the application, the related performance of the composite material provided by the application is illustrated in combination with the drawings.

[0083] Figure 1 The surface of the three samples 5Gr15BN, 10Gr10BN and 15Gr5BN after SPS sintering, sanding and polishing;

[0084] After the sample is polished and polished, the surface is smooth and flat, and the black and white phases are uniformly distributed.

[0085] Figure 2The surface SEM-EDS images of three samples 5Gr15BN, 10Gr10BN, and 15Gr5BN after SPS sintering, sandpaper grinding, and polishing;

[0086] It can be seen that the elements on the sample surface are evenly distributed. ZrO2 as the matrix occupies a larger part on the material surface, and graphene and SiO2-coated BN are evenly distributed in the ZrO2 gap.

[0087] Figure 4 (a), (b), (c), and (d) are the friction coefficient curves of four ceramic materials YSZ, 5Gr15BN, 10Gr10BN, and 15Gr5BN at different temperatures respectively; Figure 5 is the comparison of average friction coefficient at different temperatures;

[0088] Depend on Figure 4 and Figure 5 The friction coefficient of YSZ at room temperature is 0.47. After adding different amounts of graphene and SiO2-coated BN, the friction coefficient decreases to around 0.2. As the graphene content increases, the friction coefficient gradually decreases. The friction coefficient of YSZ at 500°C is 0.62. After adding graphene and SiO2-coated BN, the friction coefficient gradually decreases from 0.52 to 0.09 as the graphene content increases.

[0089] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A YSZ ceramic-based self-lubricating composite material, characterized in that: The composite material includes YSZ, and graphene and SiO2-coated BN powder; The SiO2-coated BN powder and graphene are interspersed in the spherical ZrO2 matrix to connect the ZrO2; wherein the SiO2-coated BN powder is a flaky core-shell structure formed with BN powder as the core and SiO2 as the shell; The mass ratio of the YSZ, graphene and SiO2-coated BN powder is 1:0.01~0.2:0.01~0.

2.

2. The YSZ ceramic-based self-lubricating composite material according to claim 1, characterized in that: The YSZ is 7YSZ or 8YSZ.

3. The YSZ ceramic-based self-lubricating composite material according to claim 1, characterized in that: The SiO2-coated BN powder is prepared according to the following steps: After BN powder is uniformly dispersed in a mixed solution of anhydrous ethanol, NH4OH and deionized water, TEOS is added and reacted for 6 to 12 hours. The reaction product is filtered, washed and dried to obtain SiO2-coated BN powder.

4. The YSZ ceramic-based self-lubricating composite material according to claim 3, characterized in that: The volume ratio of anhydrous ethanol, NH4OH and deionized water is 20:3:4; The usage ratio of the BN powder to TEOS is 3 g:10 mL.

5. A method for preparing the YSZ ceramic-based self-lubricating composite material according to any one of claims 1 to 4, characterized in that: The following steps are involved: YSZ, graphene and SiO2-coated BN powders were ground and mixed, and passed through a 30-80 mesh sieve to obtain a mixed powder; The mixed powder is placed in a mold and sintered in a spark plasma sintering furnace at 1250-1350° C. for 10-20 minutes to obtain a YSZ ceramic-based self-lubricating composite material.

6. The method for preparing the YSZ ceramic-based self-lubricating composite material according to claim 5, characterized in that: The grinding and mixing process includes: placing YSZ, graphene and SiO2-coated BN powders into a ball mill for ball milling, wherein anhydrous ethanol and stainless steel balls are used as ball milling media, the rotation speed is 200-300°C / min, and the ball milling is performed for 1-2 hours.

7. The method for preparing the YSZ ceramic-based self-lubricating composite material according to claim 5, characterized in that: During the sintering process, the spark plasma sintering pressure is 30~50MPa; the heating rate is 50~100℃ / min.

8. The method for preparing the YSZ ceramic-based self-lubricating composite material according to claim 5, characterized in that: The mold is a graphite mold.

9. Use of the YSZ ceramic-based self-lubricating composite material according to any one of claims 1 to 4 in friction materials.

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