B4c@mg2b2o5 core-shell structure ceramic powder and preparation method thereof

Abstract

The application discloses a kind of B4C@Mg2B2O5 core-shell structure ceramic powder and preparation method thereof, comprising the following steps: (1) boron carbide powder, magnesium oxide powder and organic solvent are mixed, ultrasonic dispersion 1-2h, and obtain mixture material;(2) the mixture material is laid up after high temperature drying and grinds 0.5-2h, and obtain precursor powder;(3) the precursor powder is placed in alumina crucible, and the alumina crucible is placed in tube furnace, calcination 0.5-1.5h under air atmosphere;(4) switch to nitrogen atmosphere, continue to heat calcination 0.5-1h, and then high temperature annealing is obtained B4C@Mg2B2O5 ceramic powder.The ceramic powder prepared by the application can be sintered into shape at a lower temperature, has higher mechanical properties, reduces the sintering cost of boron carbide composite material, and improves its toughness.At the same time, the application can be applied to polishing grinding and other industrial scenes, widens the application range of boron carbide material, and has certain grinding application value in grinding field.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of material synthesis, and particularly relates to a B4C@Mg2B2O5 core-shell structure ceramic powder and a preparation method thereof. BACKGROUND

[0002] The boron carbide material is an excellent ceramic material, has various excellent performances, and has the characteristics of being very hard, having good thermal stability, and being capable of absorbing thermal neutrons, but poor impact resistance and great brittleness.

[0003] At present, the large-area application of the boron carbide material still faces certain problems: firstly, since the B4C is a brittle ceramic, a hot-pressing sintering method is generally adopted for preparation, but the cooling needs to be slow and the hot-pressing temperature should not be too high, otherwise the B4C-C eutectic liquid phase appears, and the hot-pressing temperature should not be too low, otherwise the powder density is low, so that the B4C sintering condition is harsh, the cost is high, and the single-phase B4C ceramic has low toughness and poor machining capability. Secondly, the boron carbide ceramic can be used as an abrasive and a cutting tool due to the characteristic of high hardness, but the machined surface of the material polished by the boron carbide has high roughness, which causes few applicable machining materials, and is not conducive to large-area application in industry. SUMMARY

[0004] The application aims at overcoming the defects of the prior art, and provides a B4C@Mg2B2O5 core-shell structure ceramic powder and a preparation method thereof, which solve the problems in the background.

[0005] The application solves the technical problems by adopting the technical scheme that a preparation method of a B4C@Mg2B2O5 core-shell structure ceramic powder is provided, and the method comprises the following steps:

[0006] (1) mixing boron carbide powder, magnesium oxide powder and an organic solvent, ultrasonic dispersion for 1-2h to obtain a mixture;

[0007] (2) high-temperature drying and grinding the mixture for 0.5-2h after being laid flat to obtain a precursor powder;

[0008] (3) placing the precursor powder in an alumina crucible, placing the alumina crucible in a tube furnace, and calcining under air atmosphere for 0.5-1.5h;

[0009] (4) switching to a nitrogen atmosphere, continuing to heat and calcine for 0.5-1h, and then annealing at high temperature to obtain the B4C@Mg2B2O5 ceramic powder.

[0010] In step (1) of the present application, the boron carbide powder and the magnesium oxide powder have a large size ratio. Specifically, the particle size of the boron carbide powder is 5-10 μm, and the particle size of the magnesium oxide powder is 50-100 nm. The mass ratio of the boron carbide powder and the magnesium oxide powder is 0.2 g:0.12-0.15 g.

[0011] As one of the preferred embodiments of the preparation method of the B4C@Mg2B2O5 core-shell structure ceramic powder of the present application, the particle sizes of the boron carbide powder and the magnesium oxide powder are 10 μm and 100 nm, respectively, and the dosage ratio of the boron carbide powder and the magnesium oxide powder is 0.152-0.203 g:0.11-0.147 g.

[0012] In step (1) of the present application, the organic solvent includes ethanol and isopropanol.

[0013] In step (2) of the present application, the thickness of the powder layer after the flattening is not greater than 1 mm.

[0014] In step (3) of the present application, the calcination temperature in the air atmosphere is 600-700 °C.

[0015] As one of the preferred embodiments of the preparation method of the B4C@Mg2B2O5 core-shell structure ceramic powder of the present application, the calcination temperature in the air atmosphere is 640-700 °C, and the time is 90 min.

[0016] In step (4) of the present application, the heating rate in the nitrogen atmosphere is 10 °C / min, the calcination temperature is 900-1000 °C, and the holding time is 30 min.

[0017] As one of the preferred embodiments of the preparation method of the B4C@Mg2B2O5 core-shell structure ceramic powder of the present application, the high-temperature annealing temperature is 900-1000 °C, and the cooling rate is 10 °C / min.

[0018] The present application solves the technical problem and further provides the B4C@Mg2B2O5 core-shell structure ceramic powder prepared by the above method, and the shell thickness is about 100±1 nm.

[0019] Compared with the background art, the technical solution has the following advantages:

[0020] 1. The present application is simple and easy to operate, has low preparation condition requirements, and has the advantages of adjustable core-shell powder size, high product purity, etc.

[0021] 2. The core-shell structure B4C@Mg2B2O5 core-shell structure ceramic material prepared by the present application can be sintered at a relatively low temperature, has high mechanical properties, reduces the sintering cost of the boron carbide composite material, and improves the toughness.

[0022] 3. The B4C@Mg2B2O5 shell structure ceramic powder material prepared by the method has application value in the field of grinding processing. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 X-ray diffraction pattern of the B4C@Mg2B2O5 core-shell structure ceramic powder prepared for the example.

[0024] Figure 2 Electron microscope images of the B4C@Mg2B2O5 core-shell structure ceramic powder prepared for the example at different magnifications.

[0025] Figure 3 Surface image of a silicon carbide wafer C face before processing.

[0026] Figure 4 Surface image of a silicon carbide wafer C face after processing. DETAILED DESCRIPTION

[0027] Example 1

[0028] The B4C@Mg2B2O5 shell structure ceramic powder material of the example, the preparation method comprises the following steps:

[0029] (1) 0.203 g of boron carbide powder (10 μm), 0.147 g of magnesium oxide powder (100 nm) and 50 mL of ethanol were mixed and dispersed in a beaker to obtain a mixed solution, and the beaker containing the mixed solution was placed in an ultrasonic cleaner for ultrasonic dispersion for 1 h;

[0030] (2) The material obtained in step (1) was dried at high temperature and ground for 1 h to obtain a precursor powder, which was laid flat in an alumina crucible with a powder layer thickness of 1 mm and left to stand;

[0031] (3) The crucible containing the precursor powder was placed in a tube furnace and calcined at 650℃ in an air atmosphere for 1.5 h;

[0032] (4) Switch to a nitrogen atmosphere and continue to heat to 950℃ for calcination for 0.5 h, and then anneal at high temperature to obtain a B4C@Mg2B2O5 core-shell structure ceramic powder, and the shell layer thickness is about 100±1 nm.

[0033] (5) The obtained B4C@Mg2B2O5core-shell structure ceramic powder was sintered under a nitrogen atmosphere at 1150°C, and the microhardness of the sample was determined on a ZHV-1MDXS high-level semi-automatic microphotometer. The test instrument used a right tetrahedral pyramid diamond indenter, which was pressed into the sample surface under a test force of 1.96N. After a holding time of 10s, the maximum microhardness of the sample was as high as 2577HV, and the highest fracture toughness was 4.8MPa·m 1 / 2 , which was 60% higher than that of pure boron carbide material.

[0034] Example 2

[0035] The B4C@Mg2B2O5shell structure ceramic powder material of the present example has a preparation method comprising the following steps:

[0036] (1) 0.203g of boron carbide powder (10μm), 0.147g of magnesium oxide powder (100nm) and 50mL of ethanol were mixed and dispersed in a beaker to obtain a mixed solution, and the beaker containing the mixed solution was placed in an ultrasonic cleaner for ultrasonic dispersion for 1h;

[0037] (2) The material obtained in step (1) was high-temperature dried and ground for 1h to obtain a precursor powder, which was laid flat in an alumina crucible with a powder layer thickness of 1mm and left to stand;

[0038] (3) The crucible containing the precursor powder was placed in a tube furnace and calcined at 650°C under an air atmosphere for 1.5h;

[0039] (4) The atmosphere was switched to nitrogen, and the temperature was continued to rise to 950°C for calcination for 0.5h, and then high-temperature annealing was performed to obtain the B4C@Mg2B2O5core-shell structure ceramic powder as shown in Figure 2 , and the shell layer thickness was about 100±1nm.

[0040] (5) The obtained B4C@Mg2B2O5core-shell structure ceramic powder and ceramic bonding agent were mixed and dispersed, and calcined at 780°C under an air atmosphere for 2h to obtain a standard friction block with a size of 21mm*4mm*4mm. The C face of a silicon carbide wafer with a surface roughness Ra of 12nm was ground using the prepared standard friction block on a high-speed friction and wear testing machine with a model number of MFT-5000, and the surface image before processing was as shown in Figure 3 , and the processing was carried out under dry friction conditions with a load of 5N and a rotational speed of 1000rpm / min for 10min. The maximum value of the surface roughness Ra of the processed area was 4.529nm and the minimum value was 2.777nm, as shown in Figure 4 .

[0041] The above examples are only used to illustrate the technical solutions of the present application, but not to limit the present application; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some or all of the technical features can be replaced by equivalent replacements; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing B4C@Mg2B2O5 core-shell structured ceramic powder, characterized in that: Includes the following steps: (1) Mix boron carbide powder, magnesium oxide powder and organic solvent, and ultrasonically disperse for 1-2 hours to obtain a mixture; the particle size of the boron carbide powder is 5-10 μm and the particle size of the magnesium oxide powder is 50-100 nm; the mass ratio of the boron carbide powder to the magnesium oxide powder is 0.2 g: 0.12-0.15 g. (2) The mixture is spread out, dried at high temperature and ground for 0.5-2 hours to obtain precursor powder; (3) Place the precursor powder in an alumina crucible, place the alumina crucible in a tube furnace, and calcine it at 600-700 °C for 0.5-1.5 h in an air atmosphere; (4) Switch to nitrogen atmosphere, continue heating at a rate of 10 °C / min to 900-1000 °C for 0.5-1h, and then anneal at a rate of 10 °C / min to obtain B4C@Mg2B2O5 ceramic powder.

2. The method for preparing B4C@Mg2B2O5 core-shell structured ceramic powder according to claim 1, characterized in that: In step (1), the organic solvent is ethanol or isopropanol.

3. The method for preparing B4C@Mg2B2O5 core-shell structured ceramic powder according to claim 1, characterized in that: In step (2), the thickness of the powder layer after spreading is no more than 1 mm.

4. A B4C@Mg2B2O5 core-shell structured ceramic powder, characterized in that: It is prepared by the method described in any one of claims 1-3.

5. The B4C@Mg2B2O5 core-shell structured ceramic powder according to claim 4, characterized in that: The shell thickness is 100±1nm.

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