High-temperature-resistant composite ceramic material and preparation method thereof

Abstract

The invention relates to the field of ceramic materials, in particular to a high-temperature-resistant composite ceramic material and a preparation method thereof.The high-temperature-resistant composite ceramic material is prepared from, by weight, 80-100 parts of zirconium oxide, 10-20 parts of silicon carbide, 5-10 parts of aluminum nitride, 1-5 parts of a sintering aid and 5-10 parts of modified silicon powder; the modified silicon powder takes nano silicon powder as a core body, the core body is sequentially coated with a transition metal organic polymer and oxidized asphalt, and the prepared composite ceramic material is good in mechanical strength and excellent in high temperature resistance and has important application value in the field of aerospace.

Description

Technical Field

[0001] The present invention relates to the field of ceramic materials, and particularly to a high-temperature resistant composite ceramic material and a preparation method thereof. Background Art

[0002] With the extensive application of ceramic materials in the aerospace field, higher requirements are put forward for their high-temperature resistance. As a common oxide ceramic, zirconia is commonly used as the matrix material for refractory ceramics and ultra-high temperature structural ceramics. Zirconia has stable chemical properties and excellent mechanical properties. However, when the temperature is too high, the zirconia ceramic material will creep, resulting in plastic deformation and strength reduction, and large temperature gradients and thermal stresses will also be generated inside, causing phenomena such as cracks, spalling or chipping, which further limits its application in high-temperature environments. Summary of the Invention

[0003] Object of the Invention: Aiming at the above technical problems, the present invention provides a high-temperature resistant composite ceramic material and a preparation method thereof.

[0004] The technical solution adopted is as follows:

[0005] A high-temperature resistant composite ceramic material is prepared from the following raw materials in parts by weight:

[0006] 80 - 100 parts of zirconia, 10 - 20 parts of silicon carbide, 5 - 10 parts of aluminum nitride, 1 - 5 parts of sintering aid, 5 - 10 parts of modified silicon powder;

[0007] The modified silicon powder has a nano-silicon powder as the core, and the core is sequentially coated with a transition metal organic polymer and oxidized asphalt.

[0008] Further, the sintering aid is composed of yttrium oxide, magnesium oxide, titanium dioxide, lanthanide rare earth fluoride and lanthanide rare earth oxide.

[0009] Further, the lanthanide rare earth fluoride is at least one of lanthanum fluoride, gadolinium fluoride, dysprosium fluoride, ytterbium fluoride.

[0010] Further, the lanthanide rare earth fluoride is ytterbium fluoride.

[0011] Further, the lanthanide rare earth oxide is lanthanum oxide and / or cerium oxide.

[0012] Further, the lanthanide rare earth oxide is lanthanum oxide.

[0013] Further, the mass ratio of yttrium oxide, magnesium oxide, titanium dioxide, rare earth fluoride and rare earth oxide is 1 - 5:1 - 5:1 - 5:1 - 5:1 - 5.

[0014] Further, the mass ratio of yttrium oxide, magnesium oxide, titanium dioxide, rare earth fluoride and rare earth oxide is 2:2:2:1:1.

[0015] Further, the transition metal organic polymer is polyvinyl ferrocene.

[0016] Further, the preparation method of the oxidized asphalt is as follows:

[0017] Add medium-temperature coal tar pitch into a reaction kettle, heat it from room temperature to 250-350 °C under an air atmosphere, keep it for reaction for 1-5 h, and then cool it down.

[0018] Further, the preparation method of the modified silicon powder is as follows:

[0019] Under nitrogen protection, add nano-silicon powder into toluene, after ultrasonic dispersion, add vinyl ferrocene and a radical initiator to obtain a reaction solution, place the reaction solution in a water bath environment at 55-65 °C for reaction for 5-10 h, then stop passing nitrogen and cool the reaction solution to room temperature. Subsequently, add methanol, collect the precipitate, wash and dry to obtain an intermediate. Dissolve the oxidized asphalt in tetrahydrofuran and then add the intermediate, stir well and heat to evaporate tetrahydrofuran.

[0020] The present invention also provides a preparation method of a high-temperature resistant composite ceramic material:

[0021] Mix zirconia, silicon carbide, aluminum nitride, a sintering aid and the modified silicon powder and ball-mill them, then press them into a green body under a pressure of 100-200 MPa. Heat-press and pre-sinter the green body in an inert gas atmosphere at 600-800 °C and 10-20 MPa for 1-5 h, and then keep the pressure and raise the temperature to 1300-1500 °C for continuous sintering for 1-5 h.

[0022] Further, the sintering is carried out under a magnetic field, and the magnetic field intensity is 1-10 T.

[0023] Further, the magnetic field intensity is 8 T.

[0024] Advantages of the present invention:

[0025] The present invention provides a high-temperature resistant composite ceramic material and a preparation method thereof. Yttrium oxide and zirconia can form a solid solution, inhibit the transformation of zirconia from the tetragonal phase to the monoclinic phase at high temperatures, avoid volume expansion and microcracks caused by phase transformation, thereby enhancing its creep resistance and improving the mechanical strength and high-temperature stability of the ceramic material. Magnesium oxide reacts with zirconia at high temperatures to form a eutectic liquid phase, accelerating particle rearrangement and densification. Titanium dioxide can reduce the sintering activation energy of zirconia and promote low-temperature densification, and part of Ti 4+ substitutes for Zr 4+, causing lattice distortion and the mechanical strength of the ceramic material. Fluorides can decompose and react during sintering to form low-melting compounds, promoting liquid-phase sintering. Rare-earth oxides have high activity and mainly segregate at grain boundaries. By promoting the formation of a liquid phase with a lower melting point and using the liquid phase to fill voids, the ceramic material is densified;

[0026] Oxidized asphalt and vinylferrocene are co-coated on the surface of nano-silicon powder. As a transition metal organic polymer, vinylferrocene decomposes at high temperatures to form nano-iron particles. The iron nano-particles form a liquid phase at high temperatures, adsorb silicon and carbon atoms, and then precipitate from the droplets to form silicon carbide nanowires. As a reinforcing phase, the silicon carbide nanowires achieve efficient stress transfer and heat conduction through crack bridging, pull-out effect, and load transfer, enabling the composite ceramic material to have ultra-high strength, high fracture toughness, and excellent high-temperature resistance. High-temperature oxidation can promote further cross-linking polymerization and polycondensation of asphalt molecules, enhance the thermal stability of the carbon source, ensure uniform carbon release, and more easily form an amorphous carbon layer during hot pressing pre-sintering, avoiding uneven carbon distribution caused by too rapid pyrolysis, which affects the formation of silicon carbide nanowires. Magnetic field sintering can change the disordered state of silicon carbide nanowires to an oriented arrangement along the magnetic field direction, further enhancing the mechanical strength and temperature conduction ability. The above mechanism is speculated by the inventor based on performance test results and existing technologies, and there may be defects or imperfections, which do not affect the creativity of the technical solution of the present invention. The composite ceramic material prepared by the present invention has good mechanical strength and excellent high-temperature resistance, and has important application value in the aerospace field. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of the modified silicon powder prepared in Example 1. The labels in the figure represent respectively:

[0028] 1 - nano-silicon powder, 2 - vinylferrocene, 3 - oxidized asphalt.

[0029] Figure 2 It is a SEM image of the cross-section of the high-temperature resistant composite ceramic material prepared in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] For those not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase. Technologies not mentioned in the present invention refer to the prior art. Unless otherwise specified, the following examples and comparative examples are parallel tests and adopt the same treatment steps and parameters.

[0031] Zirconia: purity 99.9%, 200 mesh, Henan Dongli New Materials Co., Ltd.;

[0032] Silicon carbide: purity 99.5%, 100 mesh, Dachun (Hebei) Building Materials Technology Co., Ltd.;

[0033] Aluminum nitride: purity 99.9%, 50 nm, Wuhan Lanaibai Pharmaceutical Chemical Co., Ltd.;

[0034] Yttrium oxide: purity 99.99%, 80 mesh, Jinan Rongzheng Chemical Co., Ltd.;

[0035] Magnesium oxide: purity 99.9%, 400 mesh, Jinan Rongzheng Chemical Co., Ltd.;

[0036] Titanium dioxide: purity 99%, 200 mesh, Zhengzhou Wanda New Materials Technology Co., Ltd.;

[0037] Ytterbium fluoride: purity 99%, 200 mesh, Wuhan Chengtian Fine Chemical Co., Ltd.;

[0038] Lanthanum oxide: purity 99.99%, 100 mesh, Shandong Kepler Biotechnology Co., Ltd.;

[0039] Modified silicon powder: self-made.

[0040] Example 1:

[0041] A high-temperature resistant composite ceramic material is prepared from the following raw materials in parts by weight:

[0042] 85 parts of zirconia, 15 parts of silicon carbide, 10 parts of aluminum nitride, 1 part of yttrium oxide, 1 part of magnesium oxide, 1 part of titanium dioxide, 0.5 part of ytterbium fluoride, 0.5 part of lanthanum oxide, 8 parts of modified silicon powder;

[0043] The modified silicon powder uses nano-silicon powder 1 as the core, and is sequentially coated with polyvinyl ferrocene 2 and oxidized asphalt 3 on the outside of the core. The preparation method of the modified silicon powder is as follows:

[0044] Add 100 g of medium-temperature coal tar pitch to the reaction kettle, and heat it from room temperature to 320 °C at a rate of 10 °C / min under an air flow of 80 ml / min. After holding the reaction for 5 h, naturally cool it to room temperature to obtain oxidized asphalt. Under nitrogen protection, add 100 g of nano-silicon powder to 500 ml of toluene, ultrasonically disperse it for 30 min, then add 35 g of vinyl ferrocene and 1 g of free radical initiator AIBN to obtain a reaction solution. Place the reaction solution in a 60 °C water bath environment and stir it for 5 - 10 h. Stop passing nitrogen and cool the reaction solution to room temperature. Then slowly drop it into 5000 ml of methanol. After dropping, let it stand for 30 min and then filter. Collect the precipitate, wash it with methanol and then dry it under vacuum to obtain an intermediate. Dissolve 50 g of oxidized asphalt in 500 ml of tetrahydrofuran, add the intermediate, stir well to mix evenly, and then transfer it to an 80 °C oven to evaporate tetrahydrofuran.

[0045] Preparation method of the above high-temperature resistant composite ceramic material:

[0046] Add zirconia, silicon carbide, aluminum nitride, yttrium oxide, magnesium oxide, titanium dioxide, ytterbium fluoride, lanthanum oxide and modified silicon powder into the ball milling tank of a planetary ball mill. After ball milling for 10 h, add the obtained mixture into a mold and press it into a green body under 100 MPa. Then, under a pressure of 20 MPa in an argon atmosphere, first heat it to 800 °C at a rate of 1 °C / min, keep it warm and hot press and pre-sinter for 4 h. Then, keep the pressure unchanged, heat it to 1450 °C at a rate of 10 °C / min, and continue sintering for 3 h under a magnetic field strength of 8 T to obtain the high-temperature resistant composite ceramic material. By observing its cross-section, see Figure 2 , it can be seen that silicon carbide nanowires are formed.

[0047] Example 2:

[0048] A high-temperature resistant composite ceramic material is prepared from the following raw materials in parts by weight:

[0049] 100 parts of zirconia, 20 parts of silicon carbide, 10 parts of aluminum nitride, 1 part of yttrium oxide, 1 part of magnesium oxide, 1 part of titanium dioxide, 0.5 part of ytterbium fluoride, 0.5 part of lanthanum oxide, 10 parts of modified silicon powder;

[0050] The modified silicon powder uses nano-silicon powder as the core body, and is sequentially coated with polyvinyl ferrocene and oxidized asphalt on the outside of the core. The preparation method of the modified silicon powder is the same as that in Example 1;

[0051] Preparation method of the above high-temperature resistant composite ceramic material:

[0052] Add zirconia, silicon carbide, aluminum nitride, yttrium oxide, magnesium oxide, titanium dioxide, ytterbium fluoride, lanthanum oxide and modified silicon powder into the ball milling tank of a planetary ball mill. After ball milling for 10 h, add the obtained mixture into a mold and press it into a green body under 100 MPa. Then, under a pressure of 20 MPa in an argon atmosphere, first heat it to 800 °C at a rate of 1 °C / min, keep it warm and hot press and pre-sinter for 4 h. Then, keep the pressure unchanged, heat it to 1450 °C at a rate of 10 °C / min, and continue sintering for 3 h.

[0053] Example 3:

[0054] A high-temperature resistant composite ceramic material is prepared from the following raw materials in parts by weight:

[0055] 80 parts of zirconia, 10 parts of silicon carbide, 5 parts of aluminum nitride, 1 part of yttrium oxide, 1 part of magnesium oxide, 1 part of titanium dioxide, 0.5 part of ytterbium fluoride, 0.5 part of lanthanum oxide, 5 parts of modified silicon powder;

[0056] The modified silicon powder uses nano-silicon powder as the core, and is successively coated with polyvinyl ferrocene and oxidized asphalt outside the core. The preparation method of the modified silicon powder is the same as that in Example 1;

[0057] The preparation method of the above high-temperature resistant composite ceramic material:

[0058] Add zirconia, silicon carbide, aluminum nitride, yttrium oxide, magnesium oxide, titanium dioxide, ytterbium fluoride, lanthanum oxide and modified silicon powder into the ball milling tank of a planetary ball mill. After ball milling for 10 h, add the obtained mixture into a mold and press it into a green body under 100 MPa. Then, under the pressure of 20 MPa in an argon atmosphere, first heat it to 800 °C at a rate of 1 °C / min, keep it warm and hot press and pre-sinter for 4 h, then keep the pressure unchanged, heat it to 1450 °C at a rate of 10 °C / min, and continue sintering for 3 h under a magnetic field strength of 8 T.

[0059] Comparative Example 1:

[0060] It is basically the same as Example 1, except that ytterbium fluoride is not added.

[0061] Comparative Example 2:

[0062] It is basically the same as Example 1, except that lanthanum oxide is not added.

[0063] Comparative Example 3:

[0064] It is basically the same as Example 1, except that the modified silicon powder is not added.

[0065] Comparative Example 4:

[0066] It is basically the same as Example 1, except that the modified silicon powder uses nano-silicon powder as the core, and is coated with oxidized asphalt outside the core, that is, it does not contain polyvinyl ferrocene. The preparation method of the modified silicon powder is as follows:

[0067] Add 100 g of medium-temperature coal tar pitch into a reaction kettle, heat it from room temperature to 320 °C at a rate of 10 °C / min under an air flow rate of 80 ml / min, keep it warm and react for 5 h, and then naturally cool it down to room temperature to obtain oxidized asphalt. Dissolve 50 g of oxidized asphalt in 500 ml of tetrahydrofuran, add 100 g of nano-silicon powder, stir well to mix evenly, and then transfer it to an oven at 80 °C to evaporate tetrahydrofuran.

[0068] Comparative Example 5:

[0069] It is basically the same as Example 1, except that the modified silicon powder uses nano-silicon powder as the core, and is successively coated with polyvinyl ferrocene and asphalt outside the core, that is, medium-temperature coal tar pitch is used instead of oxidized asphalt. The preparation method of the modified silicon powder is as follows:

[0070] Add 100 g of nano-silicon powder to 500 ml of toluene. After ultrasonic dispersion for 30 min, add 35 g of vinyl ferrocene and 1 g of free radical initiator AIBN to obtain a reaction solution. Place the reaction solution in a water bath at 60 °C and stir for 5 - 10 h. Then stop passing nitrogen and cool the reaction solution to room temperature. Subsequently, slowly dropwise add 5000 ml of methanol. After dropping, let it stand for 30 min and then filter. Collect the precipitate, wash it with methanol, and dry it under vacuum to obtain an intermediate. Dissolve 50 g of medium-temperature coal tar pitch in 500 ml of tetrahydrofuran, add the intermediate, stir well to mix evenly, and then transfer it to an oven at 80 °C to evaporate tetrahydrofuran.

[0071] Comparative Example 6:

[0072] It is basically the same as Example 1, except that no magnetic field is applied during sintering.

[0073] Performance test:

[0074] Make specimens from the high-temperature resistant composite ceramic materials prepared in Examples 1 - 3 and Comparative Examples 1 - 6 of the present invention;

[0075] Flexural strength test: Use an electronic universal testing machine and test by the three-point bending strength method. The test temperature is 25 °C, the span is 30 mm, the downward movement speed of the indenter is 0.5 mm / min, and the specimen size is 40 mm × 5 mm × 5 mm;

[0076] Fracture toughness test: Use a Vickers hardness tester and test by the indentation method. The test temperature is 25 °C, the load is 10 kgf, and it is maintained for 15 s. By measuring the crack length and the diagonal length of the square hole, calculate the fracture toughness of the specimen according to the toughness formula;

[0077] High-temperature resistance test: Use a temperature-controlled resistance furnace. Place the specimen in an air atmosphere, heat it to 1300 °C at a heating rate of 10 °C / min, hold for 1 h, and cool it to room temperature with the furnace. Repeat 10 times, and then detect the flexural strength of the specimen again and calculate its flexural strength loss rate to characterize the high-temperature resistance of the specimen.

[0078] Each group of experiments is carried out five times. After taking the average value of the data, record it in Table 1 as follows:

[0079] Table 1:

[0080]

[0081] As can be seen from Table 1 above, the high-temperature resistant composite ceramic materials prepared by the present invention have good mechanical strength and excellent high-temperature resistance;

[0082] It can be seen from the comparison between Example 1 and Comparative Examples 1, 2, and 3 that the addition of ytterbium fluoride, lanthanum oxide, and modified silicon powder has played a positive role in improving the mechanical strength and high-temperature resistance of the high-temperature resistant composite ceramic material;

[0083] It can be seen from the comparison between Example 1 and Comparative Example 4 that when the structure of the modified silicon powder does not contain vinyl ferrocene, the improvement in the mechanical strength and high-temperature resistance of the high-temperature resistant composite ceramic material by the modified silicon powder is reduced. The reason may be that it cannot catalyze the formation of silicon carbide nanowires, and the modified silicon powder only plays a certain core-shell toughening role;

[0084] It can be seen from the comparison between Example 1 and Comparative Example 5 that when medium-temperature coal tar pitch is used instead of oxidized asphalt, the improvement in the mechanical strength and high-temperature resistance of the high-temperature resistant composite ceramic material by the modified silicon powder is reduced;

[0085] It can be seen from the comparison between Example 1 and Comparative Example 6 that applying a magnetic field during sintering has played a positive role in improving the mechanical strength and high-temperature resistance of the high-temperature resistant composite ceramic material.

[0086] The above examples are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A high temperature resistant composite ceramic material, characterized in that: It is prepared from the following raw materials in parts by weight: 80-100 parts of zirconium oxide, 10-20 parts of silicon carbide, 5-10 parts of aluminum nitride, 1-5 parts of sintering aid, 5-10 parts of modified silicon powder; The modified silicon powder has nano silicon powder as a core body, and the core body is sequentially coated with transition metal organic polymer and oxidized asphalt.

2. The high temperature resistant composite ceramic material according to claim 1, characterized in that: The sintering aid consists of yttrium oxide, magnesium oxide, titanium dioxide, lanthanum series rare earth fluoride and lanthanum series rare earth oxide.

3. The high temperature resistant composite ceramic material according to claim 2, characterized in that: The lanthanide rare earth fluoride is at least one of lanthanum fluoride, gadolinium fluoride, dysprosium fluoride and ytterbium fluoride.

4. The high temperature resistant composite ceramic material according to claim 2, characterized in that: The lanthanide rare earth oxide is lanthanum oxide and / or cerium oxide.

5. The high temperature resistant composite ceramic material according to claim 2, characterized in that: The mass ratio of yttrium oxide, magnesium oxide, titanium dioxide, rare earth fluoride and rare earth oxide is 1-5:1-5:1-5:1-5:1-5.

6. The high temperature resistant composite ceramic material according to claim 1, characterized in that: The transition metal organic polymer is polyvinylferrocene.

7. The high temperature resistant composite ceramic material according to claim 1, characterized in that: The preparation method of the oxidized asphalt is as follows: Add medium-temperature coal tar pitch into the reactor, raise the temperature from room temperature to 250-350°C in an air atmosphere, keep the temperature for 1-5 hours and then cool down.

8. The high temperature resistant composite ceramic material according to claim 1, characterized in that: The preparation method of the modified silicon powder is as follows: Under nitrogen protection, nano silicon powder is added to toluene, and after ultrasonic dispersion, vinyl ferrocene and a free radical initiator are added to obtain a reaction solution. The reaction solution is placed in a 55-65°C water bath environment to react for 5-10 hours, and then the nitrogen is stopped and the reaction solution is cooled to room temperature. Methanol is then added, and the precipitate is collected, washed, and dried to obtain an intermediate. The oxidized asphalt is dissolved in tetrahydrofuran and then added to the intermediate. After sufficient stirring, the tetrahydrofuran is evaporated and heated.

9. A method for preparing a high temperature resistant composite ceramic material according to any one of claims 1 to 8, characterized in that: Zirconium oxide, silicon carbide, aluminum nitride, sintering aid and modified silicon powder are mixed and ball-milled, and then pressed into a green body at 100-200 MPa. The green body is pre-sintered at 600-800°C and 10-20 MPa for 1-5 hours under an inert gas atmosphere, and then the temperature is raised to 1300-1500°C while maintaining pressure and sintering for 1-5 hours.

10. The method for preparing a high temperature resistant composite ceramic material according to claim 9, characterized in that: The sintering is carried out under a magnetic field with a magnetic field strength of 1-10T.

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