阅读说明：本技术 一种碳化硼与碳化硅复合陶瓷的制备方法 (Preparation method of boron carbide and silicon carbide composite ceramic ) 是由 王汝江 董世昌 于海培 孙俊艳 于 2021-12-10 设计创作，主要内容包括：本发明公开了一种碳化硼与碳化硅复合陶瓷的制备方法,属于陶瓷制备技术领域；该制备方法包括制备初级混合粉,制备混合粉,压制,辐射处理,烧结；所述制备初级混合粉,将碳化硼粉,碳化硅粉,火山石粉,纳米氮化硼混合均匀后置于球磨罐中进行液氮球磨,液氮球磨结束得到初级混合粉；本发明的制备方法能够在提高碳化硼与碳化硅复合陶瓷的精度,降低生产成本,提高生产效率的同时,降低烧结温度,提高碳化硼与碳化硅复合陶瓷的抗张强度和抗拉强度,降低脆性。(The invention discloses a preparation method of boron carbide and silicon carbide composite ceramic, belonging to the technical field of ceramic preparation; the preparation method comprises preparing primary mixed powder, preparing mixed powder, pressing, radiating and sintering; the preparation method comprises the following steps of preparing primary mixed powder, namely uniformly mixing boron carbide powder, silicon carbide powder, volcanic rock powder and nano boron nitride, putting the mixture into a ball milling tank for liquid nitrogen ball milling, and obtaining the primary mixed powder after the liquid nitrogen ball milling is finished; the preparation method of the invention can improve the precision of the boron carbide and silicon carbide composite ceramic, reduce the production cost, improve the production efficiency, reduce the sintering temperature, improve the tensile strength and tensile strength of the boron carbide and silicon carbide composite ceramic and reduce the brittleness.)

1. A preparation method of boron carbide and silicon carbide composite ceramic is characterized by comprising the steps of preparing primary mixed powder, preparing mixed powder, pressing, radiating and sintering;

the preparation of the primary mixed powder comprises the steps of uniformly mixing boron carbide powder, silicon carbide powder, volcanic rock powder and nano boron nitride, then placing the mixture into a ball milling tank for liquid nitrogen ball milling, wherein the ball-material ratio during liquid nitrogen ball milling is controlled to be 17-20:1, the liquid nitrogen accounts for 60-65% of the volume of the ball milling tank, the ball milling speed is 500-550rpm, the ball milling time is 5-5.5 hours, and the primary mixed powder is obtained after the liquid nitrogen ball milling is finished;

the preparation method comprises the steps of adding primary mixed powder, guar gum powder, tara gum powder, nano titanium dioxide, modified magnetic powder, zeolite powder, sodium hydroxide and water into a high-shear reaction kettle, adjusting the temperature of the high-shear reaction kettle to be 60-70 ℃, adjusting the shearing speed of the high-shear reaction kettle to be 5000-6000rpm, shearing for 40-50min to obtain a mixed material, placing the mixed material into a vacuum freeze dryer, vacuumizing the vacuum freeze dryer to 40-50kpa, starting refrigeration, reducing the temperature of a cold trap of the vacuum freeze dryer to-50 ℃ to-60 ℃ within 4-5 hours, and performing freeze treatment for 2-3 hours at-50 ℃ to-60 ℃; then slowly heating, raising the temperature of the mixed material to 25-30 ℃ within 10-11h, and drying at 25-30 ℃ for 3-5h to obtain mixed powder.

2. The method for preparing boron carbide and silicon carbide composite ceramic according to claim 1, wherein the boron carbide powder has a purity of 97% to 98% and a particle size of 20 to 30 μm;

the purity of the silicon carbide powder is 99-99.8%, and the particle size is 10-20 μm;

the particle size of the volcanic rock powder is 5-10 mu m;

the particle size of the nanometer boron nitride is 20-30 nm.

3. The preparation method of the boron carbide and silicon carbide composite ceramic according to claim 1, wherein the mass ratio of the boron carbide powder, the silicon carbide powder, the volcanic rock powder and the nano boron nitride is 30-35: 20-25: 5-8: 2-5.

4. The method for preparing boron carbide and silicon carbide composite ceramic according to claim 1, wherein the mass ratio of the primary mixed powder, guar gum powder, tara gum powder, nano titanium dioxide, modified magnetic powder, zeolite powder, sodium hydroxide and water is 80-85: 5-7: 2-3: 1-2: 3-4: 2-4: 1-2: 320-350.

5. The method for preparing the boron carbide and silicon carbide composite ceramic according to claim 1, wherein the method for preparing the modified magnetic powder comprises the following steps: mixing ferroferric oxide, aluminum oxide, ethanol, a rare earth coupling agent WOT and water, then performing microwave oscillation for 4-5 times, each time for 15-20s, controlling the intensity of the microwave oscillation to be 80-90W, adding 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, lecithin and acetic acid after the microwave oscillation is finished, then continuing the microwave oscillation for 2-3 times, each time for 10-15s, controlling the intensity of the microwave oscillation to be 60-70W, filtering after the microwave oscillation is finished, placing filter residues in a drying oven, and drying for 1-1.5h at 60-70 ℃ to obtain the modified magnetic powder.

6. The preparation method of the boron carbide and silicon carbide composite ceramic according to claim 5, wherein the mass ratio of ferroferric oxide, alumina, ethanol, a rare earth coupling agent WOT, water, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, lecithin and acetic acid is 30-35: 10-12: 20-25: 3-5: 100-120: 5-8: 3-5: 5-8.

7. The method for preparing boron carbide and silicon carbide composite ceramic according to claim 1, wherein the irradiation treatment is performed by using⁶⁰And (3) irradiating the Co source at 50-60 ℃, controlling the irradiation dose to be 300-400KGy, and obtaining the treated embryo body after the irradiation is finished.

8. The method for preparing boron carbide and silicon carbide composite ceramic according to claim 1, wherein the sintering comprises placing the treated blank in a crucible, placing the crucible in a pressureless sintering furnace, heating to 1600-1650 ℃ at a temperature rise rate of 5-8 ℃/min by using flowing nitrogen as a protective gas, preserving the heat for 40-50min, and naturally cooling to room temperature to obtain the boron carbide and silicon carbide composite ceramic.

Technical Field

The invention relates to the technical field of ceramic preparation, in particular to a preparation method of boron carbide and silicon carbide composite ceramic.

Background

The ceramic material is used as a key member in a non-metal material, has good mechanical property and electrochemical property, and has the advantages of low thermal conductivity, compact and uniform structure, wear resistance, corrosion resistance and the like, but the ceramic material has high brittleness, low tensile strength and tensile strength, and poor plasticity and toughness. With the development of science and technology, people have higher and higher requirements on ceramics, a single ceramic material cannot meet the requirements of people, and more people select to use the composite ceramics.

The silicon carbide and boron carbide composite ceramic has the characteristics of high hardness and light weight, is initially applied to the field of bulletproof armor, and is widely applied to different fields of mechanical grinding, refractory materials, engineering ceramics, nuclear industry, military and the like with the continuous improvement of production process and the reduction of production cost.

However, the existing method for preparing silicon carbide and boron carbide composite ceramic generally comprises the steps of mixing silicon carbide powder and boron carbide powder, and then carrying out hot-pressing sintering, wherein when carrying out hot-pressing sintering, because very high pressure and temperature are reached in a short time, the ceramic has fewer micro cracks, so that the toughness is better, and the strength is also high, but the hot-pressing sintering process and hot-pressing sintering equipment are more complicated, the requirement on the equipment is high, the processing cost is high, the production efficiency is low, the surface of a product is rough, the precision is low, and the cleaning and machining are generally needed; therefore, more and more technicians are going to research on pressureless sintering, but boron carbide and silicon carbide need to be heated to more than 2100 ℃ during pressureless sintering, the energy consumption is high, and the composite ceramic prepared by pressureless sintering has low tensile strength and high brittleness. Therefore, the development of a method for preparing boron carbide and silicon carbide composite ceramic can improve the precision of boron carbide and silicon carbide composite ceramic, reduce the production cost, improve the production efficiency, reduce the sintering temperature, improve the tensile strength and tensile strength of boron carbide and silicon carbide composite ceramic, and reduce the brittleness, which is a technical problem to be solved urgently at present.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the preparation method of the boron carbide and silicon carbide composite ceramic, which can improve the precision of the boron carbide and silicon carbide composite ceramic, reduce the production cost, improve the production efficiency, reduce the sintering temperature, improve the tensile strength and tensile strength of the boron carbide and silicon carbide composite ceramic and reduce the brittleness.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a process for preparing the composite ceramic of boron carbide and silicon carbide includes preparing the primary mixed powder, preparing the mixed powder, pressing, radiating and sintering.

The preparation method comprises the steps of uniformly mixing boron carbide powder, silicon carbide powder, volcanic rock powder and nano boron nitride, then placing the mixture into a ball milling tank for liquid nitrogen ball milling, wherein the ball-material ratio during liquid nitrogen ball milling is controlled to be 17-20:1, the liquid nitrogen accounts for 60-65% of the volume of the ball milling tank, the ball milling speed is 500-550rpm, the ball milling time is 5-5.5 hours, and the primary mixed powder is obtained after the liquid nitrogen ball milling is finished.

The purity of the boron carbide powder is 97-98%, and the particle size is 20-30 μm.

The purity of the silicon carbide powder is 99-99.8%, and the particle size is 10-20 μm.

The particle size of the volcanic rock powder is 5-10 μm.

The particle size of the nanometer boron nitride is 20-30 nm.

Wherein the mass ratio of boron carbide powder, silicon carbide powder, volcanic rock powder and nano boron nitride is 30-35: 20-25: 5-8: 2-5.

The preparation method comprises the steps of adding primary mixed powder, guar gum powder, tara gum powder, nano titanium dioxide, modified magnetic powder, zeolite powder, sodium hydroxide and water into a high-shear reaction kettle, adjusting the temperature of the high-shear reaction kettle to be 60-70 ℃, adjusting the shearing speed of the high-shear reaction kettle to be 5000-6000rpm, shearing for 40-50min to obtain a mixed material, placing the mixed material into a vacuum freeze dryer, vacuumizing the vacuum freeze dryer to 40-50kpa, starting refrigeration, reducing the temperature of a cold trap of the vacuum freeze dryer to-50 ℃ to-60 ℃ within 4-5 hours, and performing freeze treatment for 2-3 hours at-50 ℃ to-60 ℃; then slowly heating, raising the temperature of the mixed material to 25-30 ℃ within 10-11h, and drying at 25-30 ℃ for 3-5h to obtain mixed powder.

Wherein the mass ratio of the primary mixed powder, the guar gum powder, the tara gum powder, the nano titanium dioxide, the modified magnetic powder, the zeolite powder, the sodium hydroxide and the water is 80-85: 5-7: 2-3: 1-2: 3-4: 2-4: 1-2: 320-350.

The particle size of the nano titanium dioxide is 100-200 nm.

The preparation method of the modified magnetic powder comprises the following steps: mixing ferroferric oxide, aluminum oxide, ethanol, a rare earth coupling agent WOT and water, then performing microwave oscillation for 4-5 times, each time for 15-20s, controlling the intensity of the microwave oscillation to be 80-90W, adding 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, lecithin and acetic acid after the microwave oscillation is finished, then continuing the microwave oscillation for 2-3 times, each time for 10-15s, controlling the intensity of the microwave oscillation to be 60-70W, filtering after the microwave oscillation is finished, placing filter residues in a drying oven, and drying for 1-1.5h at 60-70 ℃ to obtain the modified magnetic powder.

Wherein the weight ratio of ferroferric oxide, alumina, ethanol, a rare earth coupling agent WOT, water, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, lecithin and acetic acid is 30-35: 10-12: 20-25: 3-5: 100-120: 5-8: 3-5: 5-8.

The active content of the 3-chloro-2-hydroxypropyl trimethyl ammonium chloride is 69 percent.

And in the pressing step, the mixed powder is placed in an isostatic pressing machine, and cold isostatic pressing is carried out under the condition of 150-170MPa to obtain a blank.

Said radiation treatment is carried out by⁶⁰And (3) irradiating the Co source at 50-60 ℃, controlling the irradiation dose to be 300-400KGy, and obtaining the treated embryo body after the irradiation is finished.

And sintering, namely placing the treated blank in a crucible, then placing the crucible in a pressureless sintering furnace, using flowing nitrogen as protective gas, raising the temperature to 1600-1650 ℃ at the temperature rise speed of 5-8 ℃/min, preserving the heat for 40-50min, and then naturally cooling to room temperature to obtain the boron carbide and silicon carbide composite ceramic.

Compared with the prior art, the invention has the beneficial effects that:

(1) the preparation method of the boron carbide and silicon carbide composite ceramic can improve the precision of the boron carbide and silicon carbide composite ceramic, reduce the production cost and improve the production efficiency;

(2) according to the preparation method of the boron carbide and silicon carbide composite ceramic, the modified magnetic powder is used for preparing the mixed powder, and the blank body is subjected to radiation treatment, so that the sintering temperature can be reduced from 2200 ℃ to 1600-1650 ℃, and the energy consumption is reduced;

(3) according to the boron carbide and silicon carbide composite ceramic prepared by the invention, the hardness and the strength of the boron carbide and silicon carbide composite ceramic can be improved by using the modified magnetic powder and performing radiation treatment on the blank body during preparation of the mixed powder, and the strength density of the prepared boron carbide and silicon carbide composite ceramic is 2.79-2.85g/cm³The compactness is 98.3-98.5%, the Vickers hardness is 27-30GPa, the elastic modulus is 405-410GPa, the tensile strength is 304-317MPa, the tensile strength is 97-102MPa, the bending strength is 558-567MPa, and the compressive strength is 2970-3110 MPa;

(4) according to the boron carbide and silicon carbide composite ceramic prepared by the invention, the liquid nitrogen ball milling is carried out in the step of preparing the primary mixed powder, so that the brittleness of the boron carbide and silicon carbide composite ceramic can be reduced, and the fracture toughness of the prepared boron carbide and silicon carbide composite ceramic can reach 7.5-7.9 MPa^1/2；

(5) The boron carbide and silicon carbide composite ceramic prepared by the method has high surface smoothness and low precision, and does not need further cleaning and machining.

Detailed Description

In order to more clearly understand the technical features, objects, and effects of the present invention, specific embodiments of the present invention will now be described.

Example 1

A preparation method of boron carbide and silicon carbide composite ceramic specifically comprises the following steps:

1. preparing primary mixed powder: uniformly mixing boron carbide powder, silicon carbide powder, volcanic rock powder and nano boron nitride, then placing the mixture into a ball milling tank for liquid nitrogen ball milling, wherein the ball-to-material ratio during ball milling by liquid nitrogen is controlled to be 17:1, the liquid nitrogen accounts for 60% of the volume of the ball milling tank, the ball milling speed is 500rpm, the ball milling time is 5 hours, and the primary mixed powder is obtained after the liquid nitrogen ball milling is finished.

The purity of the boron carbide powder is 97%, and the particle size is 20 μm.

The purity of the silicon carbide powder is 99%, and the particle size is 10 microns.

The particle size of the volcanic rock powder is 5 mu m.

The particle size of the nano boron nitride is 20 nm.

Wherein the mass ratio of boron carbide powder, silicon carbide powder, volcanic rock powder and nano boron nitride is 30: 20: 5: 2.

2. preparing mixed powder: adding primary mixed powder, guar gum powder, tara gum powder, nano titanium dioxide, modified magnetic powder, zeolite powder, sodium hydroxide and water into a high-shear reaction kettle, then adjusting the temperature of the high-shear reaction kettle to 60 ℃, adjusting the shearing speed of the high-shear reaction kettle to 5000rpm, shearing for 40min to obtain a mixed material, then placing the mixed material into a vacuum freeze dryer, vacuumizing the vacuum freeze dryer to 40kpa, simultaneously starting refrigeration, reducing the temperature of a cold trap of the vacuum freeze dryer to-50 ℃ within 4 hours, and carrying out freeze treatment for 2 hours at-50 ℃; then slowly heating, raising the temperature of the mixed material to 25 ℃ within 10h, and drying at 25 ℃ for 3h to obtain mixed powder.

Wherein the mass ratio of the primary mixed powder, the guar gum powder, the tara gum powder, the nano titanium dioxide, the modified magnetic powder, the zeolite powder, the sodium hydroxide and the water is 80: 5: 2: 1: 3: 2: 1: 320.

the particle size of the nano titanium dioxide is 100 nm.

The preparation method of the modified magnetic powder comprises the following steps: mixing ferroferric oxide, aluminum oxide, ethanol, a rare earth coupling agent WOT and water, then performing microwave oscillation for 4 times, 15s each time, controlling the intensity of the microwave oscillation to be 80W, adding 3-chlorine-2-hydroxypropyl trimethyl ammonium chloride, lecithin and acetic acid after the microwave oscillation is finished, then continuing the microwave oscillation, continuing the microwave oscillation for 2 times, 10s each time, controlling the intensity of the microwave oscillation to be 60W, finishing the microwave oscillation, filtering, placing filter residues in a drying oven, and drying for 1h at 60 ℃ to obtain modified magnetic powder.

Wherein the mass ratio of ferroferric oxide, alumina, ethanol, a rare earth coupling agent WOT, water, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, lecithin and acetic acid is 30: 10: 20: 3: 100: 5: 3: 5.

the active content of the 3-chloro-2-hydroxypropyl trimethyl ammonium chloride is 69 percent.

3. Pressing: and placing the mixed powder into an isostatic pressing machine, and performing cold isostatic pressing under the condition of 150MPa to obtain a blank.

4. Radiation treatment: by using⁶⁰And (3) irradiating by using a Co source at 50 ℃, controlling the irradiation dose to be 300KGy, and obtaining a treated embryo body after the irradiation is finished.

5. And (3) sintering: and (3) placing the treated blank body in a crucible, then placing the crucible in a pressureless sintering furnace, using flowing nitrogen as protective gas, heating to 1600 ℃ at the heating rate of 5 ℃/min, preserving the temperature for 40min, and then naturally cooling to room temperature to obtain the boron carbide and silicon carbide composite ceramic.

Example 2

A preparation method of boron carbide and silicon carbide composite ceramic specifically comprises the following steps:

1. preparing primary mixed powder: uniformly mixing boron carbide powder, silicon carbide powder, volcanic rock powder and nano boron nitride, then placing the mixture into a ball milling tank for liquid nitrogen ball milling, wherein the ball-to-material ratio during ball milling by liquid nitrogen is controlled to be 18:1, the liquid nitrogen accounts for 62% of the volume of the ball milling tank, the ball milling speed is 520rpm, the ball milling time is 5.2h, and the primary mixed powder is obtained after the liquid nitrogen ball milling is finished.

The purity of the boron carbide powder is 97.5%, and the particle size is 25 μm.

The purity of the silicon carbide powder is 99.5%, and the particle size is 15 microns.

The particle size of the volcanic rock powder is 8 mu m.

The particle size of the nano boron nitride is 25 nm.

Wherein the mass ratio of boron carbide powder, silicon carbide powder, volcanic rock powder and nano boron nitride is 32: 22: 7: 3.

2. preparing mixed powder: adding primary mixed powder, guar gum powder, tara gum powder, nano titanium dioxide, modified magnetic powder, zeolite powder, sodium hydroxide and water into a high-shear reaction kettle, then adjusting the temperature of the high-shear reaction kettle to 65 ℃, adjusting the shearing speed of the high-shear reaction kettle to 5500rpm, shearing for 45min to obtain a mixed material, then placing the mixed material into a vacuum freeze dryer, vacuumizing the vacuum freeze dryer to 45kpa, simultaneously starting refrigeration, reducing the temperature of a cold trap of the vacuum freeze dryer to-55 ℃ within 4.5 hours, and carrying out freeze treatment for 2.5 hours at-55 ℃; then slowly heating, raising the temperature of the mixed material to 28 ℃ within 10.5h, and drying at 28 ℃ for 4h to obtain mixed powder.

Wherein the mass ratio of the primary mixed powder, the guar gum powder, the tara gum powder, the nano titanium dioxide, the modified magnetic powder, the zeolite powder, the sodium hydroxide and the water is 82: 6: 2: 1: 3: 3: 1: 330.

the particle size of the nano titanium dioxide is 150 nm.

The preparation method of the modified magnetic powder comprises the following steps: mixing ferroferric oxide, aluminum oxide, ethanol, a rare earth coupling agent WOT and water, then performing microwave oscillation for 4 times, 18s each time, controlling the intensity of the microwave oscillation to be 85W, adding 3-chlorine-2-hydroxypropyl trimethyl ammonium chloride, lecithin and acetic acid after the microwave oscillation is finished, then continuing the microwave oscillation, continuing the microwave oscillation for 2 times, 12s each time, controlling the intensity of the microwave oscillation to be 65W, finishing the microwave oscillation, filtering, placing filter residues in a drying oven, and drying for 1.2h at 65 ℃ to obtain modified magnetic powder.

Wherein the mass ratio of ferroferric oxide, alumina, ethanol, a rare earth coupling agent WOT, water, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, lecithin and acetic acid is 32: 11: 22: 4: 110: 6: 4: 6.

the active content of the 3-chloro-2-hydroxypropyl trimethyl ammonium chloride is 69 percent.

3. Pressing: and placing the mixed powder into an isostatic pressing machine, and performing cold isostatic pressing under the condition of 160MPa to obtain a blank.

4. Radiation treatment: by using⁶⁰And (3) irradiating by using a Co source at 55 ℃, controlling the irradiation dose to be 350KGy, and obtaining a treated embryo body after the irradiation is finished.

5. And (3) sintering: and (3) placing the treated blank body in a crucible, then placing the crucible in a pressureless sintering furnace, using flowing nitrogen as protective gas, raising the temperature to 1620 ℃ at the heating rate of 7 ℃/min, preserving the temperature for 45min, and then naturally cooling to room temperature to obtain the boron carbide and silicon carbide composite ceramic.

Example 3

A preparation method of boron carbide and silicon carbide composite ceramic specifically comprises the following steps:

1. preparing primary mixed powder: uniformly mixing boron carbide powder, silicon carbide powder, volcanic rock powder and nano boron nitride, then placing the mixture into a ball milling tank for liquid nitrogen ball milling, wherein the ball-to-material ratio during ball milling by liquid nitrogen is controlled to be 20:1, the liquid nitrogen accounts for 65% of the volume of the ball milling tank, the ball milling speed is 550rpm, the ball milling time is 5.5h, and the primary mixed powder is obtained after the liquid nitrogen ball milling is finished.

The purity of the boron carbide powder is 98%, and the particle size is 30 μm.

The purity of the silicon carbide powder is 99.8%, and the particle size is 20 microns.

The particle size of the volcanic rock powder is 10 mu m.

The particle size of the nano boron nitride is 30 nm.

Wherein the mass ratio of boron carbide powder, silicon carbide powder, volcanic rock powder and nano boron nitride is 35: 25: 8: 5.

2. preparing mixed powder: adding primary mixed powder, guar gum powder, tara gum powder, nano titanium dioxide, modified magnetic powder, zeolite powder, sodium hydroxide and water into a high-shear reaction kettle, then adjusting the temperature of the high-shear reaction kettle to 70 ℃, adjusting the shearing speed of the high-shear reaction kettle to 6000rpm, shearing for 50min to obtain a mixed material, then placing the mixed material into a vacuum freeze dryer, vacuumizing the vacuum freeze dryer to 50kpa, simultaneously starting refrigeration, reducing the temperature of a cold trap of the vacuum freeze dryer to-60 ℃ within 5 hours, and carrying out freeze treatment for 3 hours at-60 ℃; then slowly heating, raising the temperature of the mixed material to 30 ℃ within 11h, and drying at 30 ℃ for 5h to obtain mixed powder.

Wherein the mass ratio of the primary mixed powder, the guar gum powder, the tara gum powder, the nano titanium dioxide, the modified magnetic powder, the zeolite powder, the sodium hydroxide and the water is 85: 7: 3: 2: 4: 4: 2: 350.

the particle size of the nano titanium dioxide is 200 nm.

The preparation method of the modified magnetic powder comprises the following steps: mixing ferroferric oxide, aluminum oxide, ethanol, a rare earth coupling agent WOT and water, then performing microwave oscillation for 5 times, each time for 20s, controlling the intensity of the microwave oscillation to be 90W, adding 3-chlorine-2-hydroxypropyl trimethyl ammonium chloride, lecithin and acetic acid after the microwave oscillation is finished, then continuing the microwave oscillation, continuing the microwave oscillation for 3 times, each time for 15s, controlling the intensity of the microwave oscillation to be 70W, finishing the microwave oscillation, filtering, placing filter residues in a drying oven, and drying for 1.5h at 70 ℃ to obtain modified magnetic powder.

Wherein the mass ratio of ferroferric oxide, alumina, ethanol, a rare earth coupling agent WOT, water, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, lecithin and acetic acid is 35: 12: 25: 5: 120: 8: 5: 8.

the active content of the 3-chloro-2-hydroxypropyl trimethyl ammonium chloride is 69 percent.

3. Pressing: and (3) placing the mixed powder into an isostatic pressing machine, and performing cold isostatic pressing under the condition of 170MPa to obtain a blank.

4. Radiation treatment: by using⁶⁰And (3) irradiating by a Co source at 60 ℃, controlling the irradiation dose to be 400KGy, and obtaining a treated embryo body after the irradiation is finished.

5. And (3) sintering: and (3) placing the treated blank body in a crucible, then placing the crucible in a pressureless sintering furnace, using flowing nitrogen as protective gas, heating to 1650 ℃ at the heating rate of 8 ℃/min, preserving the temperature for 50min, and then naturally cooling to room temperature to obtain the boron carbide and silicon carbide composite ceramic.

Comparative example 1

The preparation method of the boron carbide and silicon carbide composite ceramic described in example 1 is adopted, and the difference is that: in the step 1, the liquid nitrogen ball milling is changed into ball milling at normal temperature in the step of preparing the primary mixed powder, namely, the liquid nitrogen is not used in the ball milling process, the ball-material ratio during ball milling is controlled to be 17:1, the ball milling speed is 500rpm, and the ball milling time is 5 hours.

Comparative example 2

The preparation method of the boron carbide and silicon carbide composite ceramic described in example 1 is adopted, and the difference is that: in the step 2, modified magnetic powder is not used in the step of preparing the mixed powder; the step 5, sintering step is changed as follows: and (3) placing the treated blank body in a crucible, then placing the crucible in a pressureless sintering furnace, using flowing nitrogen as protective gas, heating to 2200 ℃ at the heating rate of 5 ℃/min, preserving the temperature for 40min, and then naturally cooling to room temperature to obtain the boron carbide and silicon carbide composite ceramic.

Comparative example 3

The preparation method of the boron carbide and silicon carbide composite ceramic described in example 1 is adopted, and the difference is that: omitting the 4 th radiation treatment; the step 5, sintering step is changed as follows: and (3) placing the treated blank body in a crucible, then placing the crucible in a pressureless sintering furnace, using flowing nitrogen as protective gas, heating to 2200 ℃ at the heating rate of 5 ℃/min, preserving the temperature for 40min, and then naturally cooling to room temperature to obtain the boron carbide and silicon carbide composite ceramic.

The density, vickers hardness, elastic modulus, tensile strength, bending strength, compressive strength, and fracture toughness of the boron carbide and silicon carbide composite ceramics prepared in examples 1 to 3 and comparative examples 1 to 3 were measured, and the results are shown below:

all percentages used in the present invention are mass percentages unless otherwise indicated.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.