Aluminum magnesium boron-lanthanum hexaboride composite ceramic material and preparation method thereof

Abstract

The present invention provides an aluminum-magnesium-boron-lanthanum hexaboride composite ceramic material and a preparation method thereof, which belongs to the technical field of composite ceramic materials. The present invention successfully prepares an aluminum-magnesium-boron-lanthanum hexaboride composite ceramic material through high-energy ball milling, compression molding, microwave pre-sintering and sintering treatment. The addition of lanthanum hexaboride in the present invention can improve the high-temperature oxidation resistance and chemical corrosion resistance of aluminum-magnesium-boron, and at the same time can refine the grains of the composite ceramic material. The present invention utilizes boron powder and boron carbide to jointly reduce the oxides of lanthanum, aluminum and magnesium to obtain a two-phase composite ceramic material of aluminum-magnesium-boron and lanthanum hexaboride without other impurity phases. The method of the present invention requires a low synthesis temperature and a lower cost than when pure boron powder is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of composite ceramic materials, and in particular to an aluminum-magnesium-boron-lanthanum hexaboride composite ceramic material and a preparation method thereof. Background Art

[0002] AlMgB 14 It has high hardness, low density, excellent thermal stability and relatively low friction coefficient, and is a relatively good wear-resistant material. 14 The hardness and toughness of the composite ceramic material formed after adding the second phase to the material will be improved to a certain extent, reaching the category of superhard materials. It can be widely used in metal cutting, mining, petrochemical industries, etc., and can greatly reduce tool wear.

[0003] Currently, the main reinforcement phases used in aluminum-magnesium-boron-based ceramics are titanium-based composite ceramics and zirconium-based composite ceramics. Few reports exist on methods for preparing aluminum-magnesium-boron-lanthanum hexaboride composite ceramics using lanthanum hexaboride as a reinforcement phase. Lanthanum hexaboride is an ideal reinforcement phase for aluminum-magnesium-boron materials due to its high melting point, high strength, wear resistance, and excellent thermal and chemical stability. Therefore, how to combine lanthanum hexaboride as a reinforcement phase with aluminum-magnesium-boron to produce a composite ceramic material with high hardness, high density, and good toughness is a currently unresolved technical challenge. Summary of the Invention

[0004] The purpose of the present invention is to provide an aluminum-magnesium-boron-lanthanum hexaboride composite ceramic material and a preparation method thereof, so as to solve the technical problem that lanthanum hexaboride is not currently used as a reinforcing phase in aluminum-magnesium-boron-based composite ceramic materials and to obtain a composite ceramic material with higher toughness and hardness.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides an aluminum magnesium boron-lanthanum hexaboride composite ceramic material, which is prepared from raw materials containing the following parts by mass:

[0007]

[0008] Furthermore, the purity of the boron powder, boron carbide powder, aluminum oxide powder, magnesium oxide powder and lanthanum oxide powder is independently ≥99.9%.

[0009] Furthermore, the particle sizes of the aluminum oxide powder, magnesium oxide powder and lanthanum oxide powder are independently 50 to 100 μm.

[0010] Furthermore, the particle sizes of the boron powder and the boron carbide powder are independently 10 to 50 nm.

[0011] The present invention also provides a method for preparing an aluminum magnesium boron-lanthanum hexaboride composite ceramic material, comprising the following steps:

[0012] 1) Mixing the raw material powders and performing high-energy ball milling to obtain ball mill material;

[0013] 2) Pressing the ball mill material into a shape to obtain a raw material body;

[0014] 3) Pre-sintering and sintering the raw material blank in sequence under microwave conditions to obtain an aluminum magnesium boron-lanthanum hexaboride composite ceramic material.

[0015] Furthermore, the parameters of the high-energy ball milling are: ball-to-material ratio of 20 to 50:1, ball milling speed of 2500 to 3500 rpm, and ball milling time of 2 to 5 hours.

[0016] Furthermore, the pressing pressure is 20-30 MPa.

[0017] Furthermore, the power of the microwave is 100-1000W, and the pre-sintering time is 10-60 minutes.

[0018] Furthermore, the parameters of the sintering treatment are: heating to 1200-1300° C. at a heating rate of 3-5° C. / min and keeping the temperature for 10-15 minutes.

[0019] Beneficial effects of the present invention:

[0020] (1) The present invention utilizes boron powder and boron carbide to jointly reduce the oxides of lanthanum, aluminum, and magnesium to obtain a two-phase composite ceramic material of aluminum-magnesium-boron and lanthanum hexaboride without other impurity phases. The method of the present invention requires a low synthesis temperature and a lower cost than that of reduction with pure boron powder.

[0021] (2) The present invention significantly reduces the sintering temperature through the microwave pre-sintering step, and the microwave pre-sintering step can further improve the density of the structure and the toughness of the composite ceramic material.

[0022] (3) The addition of lanthanum hexaboride in the present invention can improve the high-temperature oxidation resistance and chemical corrosion resistance of aluminum magnesium boron, and at the same time can refine the grains of the composite ceramic material. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 AlMgB in Example 1 14 -LaB6 composite ceramic material organization diagram;

[0024] Figure 2 AlMgB in Example 1 14 -Microscopic morphology of LaB6 composite ceramic material. DETAILED DESCRIPTION

[0025] The present invention provides an aluminum magnesium boron-lanthanum hexaboride composite ceramic material, which is prepared from raw materials containing the following parts by mass:

[0026]

[0027] In the present invention, the content of the boron powder is preferably 6 to 12 parts by mass, more preferably 8 parts by mass.

[0028] In the present invention, the content of the boron carbide powder is preferably 6 to 12 parts by mass, more preferably 8 parts by mass.

[0029] In the present invention, the content of the alumina powder is preferably 1 to 2 parts by mass, more preferably 1 part.

[0030] In the present invention, the content of the magnesium oxide powder is preferably 1.5 to 2.5 parts by mass, more preferably 2 parts by mass.

[0031] In the present invention, the content of the lanthanum oxide powder is preferably 1 to 2 parts by mass, more preferably 1 part.

[0032] In the present invention, the purity of the boron powder, boron carbide powder, aluminum oxide powder, magnesium oxide powder and lanthanum oxide powder is independently ≥99.9%, preferably 99.95%.

[0033] In the present invention, the particle sizes of the aluminum oxide powder, magnesium oxide powder and lanthanum oxide powder are independently 50 to 100 μm, preferably 60 to 80 μm, and more preferably 70 μm.

[0034] In the present invention, the particle size of the boron powder and the boron carbide powder is independently 10 to 50 nm, preferably 20 to 40 nm, and more preferably 30 nm.

[0035] The present invention also provides a method for preparing an aluminum magnesium boron-lanthanum hexaboride composite ceramic material, comprising the following steps:

[0036] 1) Mixing the raw material powders and performing high-energy ball milling to obtain ball mill material;

[0037] 2) Pressing the ball mill material into a shape to obtain a raw material body;

[0038] 3) Pre-sintering and sintering the raw material blank in sequence under microwave conditions to obtain an aluminum magnesium boron-lanthanum hexaboride composite ceramic material.

[0039] In the present invention, the reaction of the raw material powder is:

[0040] La2O3+Al2O3+2MgO+8B4C+8B=2AlMgB 14+2LaB6+8CO(g).

[0041] In the present invention, the parameters of the high-energy ball milling are: ball-to-material ratio is 20-50:1, preferably 30-40:1, and more preferably 35:1; ball milling speed is 2500-3500 rpm, preferably 3000 rpm; ball milling time is 2-5 h, preferably 3-4 h, and more preferably 3.5 h.

[0042] In this invention, the ball-to-material ratio during high-energy ball milling must be strictly controlled between 20 and 50:1. Research has found that when the ball-to-material ratio is lower than 20:1, the raw materials are unevenly refined, affecting the subsequent sintering step and causing uneven distribution of the two phases. When the ball-to-material ratio is higher than 50:1, the raw materials severely agglomerate during microwave pre-sintering, significantly reducing the density of the composite ceramic material. Therefore, a ball-to-material ratio of 20 to 50:1 achieves optimal material performance.

[0043] In the present invention, the pressure of the compression molding is 20-30 MPa, preferably 25 MPa.

[0044] In the present invention, the power of the microwave is 100-1000 W, preferably 200-800 W, more preferably 300-500 W; the pre-sintering time is 10-60 min, preferably 20-40 min, more preferably 30 min.

[0045] In the present invention, the parameters of the sintering treatment are: heating to 1200-1300°C at a heating rate of 3-5°C / min and keeping warm for 10-15 minutes; preferably, heating to 1250°C at a heating rate of 4°C / min and keeping warm for 12 minutes.

[0046] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0047] Example 1

[0048] 1) B powder, B4C powder, MgO powder, Al2O3 powder, and La2O3 powder were ultrasonically cleaned in ethanol solution, removed, dried, and set aside. The purity of the raw powders was ≥99.9%, wherein the particle sizes of MgO powder, Al2O3 powder, and La2O3 powder were 50 μm, 60 μm, and 60 μm, respectively; the particle sizes of B powder and B4C powder were 35 nm and 50 nm, respectively.

[0049] 2) Mix 8 parts of B powder, 8 parts of B4C powder, 2 parts of MgO powder, 1 part of Al2O3 powder, and 1 part of La2O3 powder to obtain a raw material powder. Place the raw material powder in a high-energy ball mill with a ball-to-material ratio of 35:1 and steel balls at a speed of 3000 rpm for 3.5 hours to obtain a ball-milled material.

[0050] 3) placing the ball mill in a silicon carbide mold and pressing it at 25 MPa to obtain a raw material body; placing the raw material body in a heat preservation body, and then placing the heat preservation body in a microwave oven for pre-burning for 30 minutes, with the microwave power set to 600 W, taking out the raw material body and placing it in a muffle furnace, heating it to 1200 ° C at a heating rate of 5 ° C / min, and keeping it warm for 10 minutes to obtain AlMgB 14 -LaB6 composite ceramic material.

[0051] The reaction of the raw powder is:

[0052] La2O3+Al2O3+2MgO+8B4C+8B=2AlMgB 14 +2LaB6+8CO(g).

[0053] Example 2

[0054] Step 1) is the same as in Example 1.

[0055] 2) Mix 9 parts of B powder, 9 parts of B4C powder, 2 parts of MgO powder, 1 part of Al2O3 powder, and 1 part of La2O3 powder to obtain a raw material powder. Place the raw material powder in a high-energy ball mill with a ball-to-material ratio of 50:1 and steel balls at a speed of 3000 rpm for 2 hours to obtain a ball-milled material.

[0056] 3) placing the ball mill in a silicon carbide mold and pressing it at 25 MPa to obtain a raw material body; placing the raw material body in a heat preservation body, and then placing the heat preservation body in a microwave oven for pre-burning for 30 minutes, with the microwave power set to 500 W, taking out the raw material body and placing it in a muffle furnace, heating it to 1250 ° C at a heating rate of 5 ° C / min, and keeping it warm for 10 minutes to obtain AlMgB 14 -LaB6 composite ceramic material.

[0057] Example 3

[0058] Step 1) is the same as in Example 1.

[0059] 2) Mix 9 parts of B powder, 9 parts of B4C powder, 2 parts of MgO powder, 1 part of Al2O3 powder, and 1 part of La2O3 powder to obtain a raw material powder. Place the raw material powder in a high-energy ball mill with a ball-to-material ratio of 20:1 and steel balls at a speed of 3500 rpm for 5 hours to obtain a ball-milled material.

[0060] 3) placing the ball mill in a silicon carbide mold and pressing it at 25 MPa to obtain a raw material body; placing the raw material body in a heat preservation body, and then placing the heat preservation body in a microwave oven for pre-burning for 30 minutes, with the microwave power set to 1000 W, taking out the raw material body and placing it in a muffle furnace, heating it to 1200°C at a heating rate of 3°C / min, and keeping it warm for 12 minutes to obtain AlMgB 14 -LaB6 composite ceramic material.

[0061] Example 4

[0062] Step 1) is the same as in Example 1.

[0063] 2) Mix 7 parts of B powder, 7 parts of B4C powder, 1.5 parts of MgO powder, 1 part of Al2O3 powder, and 1 part of La2O3 powder to obtain a raw material powder. Place the raw material powder in a high-energy ball mill with a ball-to-material ratio of 40:1 and steel balls at a speed of 3500 rpm for 3 hours to obtain a ball-milled material.

[0064] 3) placing the ball milled material in a silicon carbide mold and pressing it at 30 MPa to obtain a raw material body; placing the raw material body in a heat preservation body, and then placing the heat preservation body in a microwave oven for pre-burning for 30 minutes, with the microwave power set to 200 W, taking out the raw material body and placing it in a muffle furnace, heating it to 1300°C at a heating rate of 3°C / min, and keeping it warm for 12 minutes to obtain AlMgB 14 -LaB6 composite ceramic material.

[0065] Comparative Example 1

[0066] Same as Example 1, except that the parameters of high-energy ball milling are different: the ball-to-material ratio is 10:1.

[0067] Comparative Example 2

[0068] Same as Example 1, except that the parameters of high-energy ball milling are different: the ball-to-material ratio is 80:1.

[0069] Comparative Example 3

[0070] The same as Example 1, except that microwave pre-sintering is not used, and the sintering treatment is directly carried out in a muffle furnace with a sintering temperature of 1600° C. and a holding time of 30 minutes.

[0071] The properties of the composite ceramic materials obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were measured, and the results are shown in Table 1 below:

[0072] Table 1 Performance test results

[0073] project Hardness / GPa <![CDATA[Fracture toughness / MPam 1 / 2 > Density / % Example 1 53 25.1 99.5 Example 2 52 24.5 99.5 Example 3 49 23.9 99.5 Example 4 48 23.5 99.5 Comparative Example 1 35 5.5 95.0 Comparative Example 2 40 10 88.1 Comparative Example 3 32 6.5 90.6

[0074] From the above examples, it can be seen that the present invention provides aluminum magnesium boron-lanthanum hexaboride composite ceramic material and its preparation method. Figure 1 It can be seen that the present invention successfully prepared AlMgB with LaB6 reinforcement phase. 14 -LaB6 composite ceramic material. Figure 2 It shows that the LaB6 reinforcement phase is evenly distributed and has a high density of up to 99.5%. 14 -LaB6 composite ceramic material, and the hardness of the obtained composite ceramic material has been significantly improved to 48~53GPa, and the fracture toughness is 23.5~25.1MPam 1 / 2 The present invention makes full use of the excellent chemical and mechanical properties of LaB6 and successfully synthesizes AlMgB6 under relatively mild conditions. 14 -LaB6 phase, broadening the AlMgB 14 -Application scope of LaB6 composite ceramic materials.

[0075] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An aluminum magnesium boron-lanthanum hexaboride composite ceramic material, characterized in that: Prepared from the following raw materials in parts by weight: 5-15 parts of boron powder; 5-15 parts of boron carbide powder; 0.5~3 parts of alumina powder; 1-3 parts of magnesium oxide powder; 0.5-3 parts of lanthanum oxide powder; The preparation method of the aluminum magnesium boron-lanthanum hexaboride composite ceramic material comprises the following steps: 1) Mix the raw material powders and perform high-energy ball milling to obtain ball milling materials; 2) Pressing the ball abrasive into shape to obtain a raw material blank; 3) Pre-sintering and sintering the raw material blank in sequence under microwave conditions to obtain an aluminum magnesium boron-lanthanum hexaboride composite ceramic material; The parameters of the high-energy ball milling are: ball-to-material ratio of 20-50:1, ball milling speed of 2500-3500 rpm, and ball milling time of 2-5 h; The parameters of the sintering treatment are: heating to 1200-1300° C. at a heating rate of 3-5° C. / min and keeping the temperature for 10-15 minutes.

2. The aluminum magnesium boron-lanthanum hexaboride composite ceramic material according to claim 1, characterized in that: The boron powder, boron carbide powder, aluminum oxide powder, magnesium oxide powder and lanthanum oxide powder have independently a purity of ≥99.9%.

3. The aluminum magnesium boron-lanthanum hexaboride composite ceramic material according to claim 2, characterized in that: The particle sizes of the aluminum oxide powder, magnesium oxide powder and lanthanum oxide powder are independently 50-100 μm.

4. The aluminum magnesium boron-lanthanum hexaboride composite ceramic material according to claim 1 or 2, characterized in that: The particle sizes of the boron powder and the boron carbide powder are independently 10-50 nm.

5. The method for preparing the aluminum magnesium boron-lanthanum hexaboride composite ceramic material according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) Mix the raw material powders and perform high-energy ball milling to obtain ball milling materials; 2) Pressing the ball abrasive into shape to obtain a raw material blank; 3) Pre-sintering and sintering the raw material blank in sequence under microwave conditions to obtain an aluminum magnesium boron-lanthanum hexaboride composite ceramic material; The parameters of the high-energy ball milling are: ball-to-material ratio of 20-50:1, ball milling speed of 2500-3500 rpm, and ball milling time of 2-5 h; The parameters of the sintering treatment are: heating to 1200-1300° C. at a heating rate of 3-5° C. / min and keeping the temperature for 10-15 minutes.

6. The method for preparing the aluminum magnesium boron-lanthanum hexaboride composite ceramic material according to claim 5, characterized in that: The pressure of the compression molding is 20-30 MPa.

7. The method for preparing the aluminum magnesium boron-lanthanum hexaboride composite ceramic material according to claim 6, characterized in that: The power of the microwave is 100-1000W, and the pre-sintering time is 10-60 minutes.

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