Joule heating rapid preparation method of submicron boron carbide particles

Abstract

The invention discloses a Joule heating rapid preparation method of submicron boron carbide particles. The Joule heating rapid preparation method specifically comprises the following steps: 1) mixing raw materials; 2) sample loading and vacuum treatment; and 3) heating reaction and sample preparation. Compared with the prior art, the method disclosed by the invention has the advantages that by utilizing the characteristics of the Joule heating technology, the preparation of the submicron boron carbide particles is realized by quickly heating and uniformly heating the raw materials, namely the boron source and the carbon source. Graphene and carbon nanotubes are selected as carbon sources, the contact area with a boron source is increased, and the graphene and the carbon nanotubes are uniformly mixed through ball milling, so that sufficient contact and reaction between the boron source and the carbon sources are ensured. In addition, the Joule heating technology has the advantages of high temperature rise speed and uniform temperature of a sample heating area, so that rapid preparation of the submicron boron carbide particles is guaranteed. The preparation method of the submicron boron carbide particles is short in time consumption and low in energy consumption, and rapid preparation of the submicron boron carbide particles can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of material preparation, and in particular to a method for rapidly preparing submicron boron carbide particles by Joule heating. Background Art

[0002] Boron carbide ceramics have been applied in aerospace, neutron shielding, and anti-ballistic fields due to their low density, high strength and stiffness, good wear resistance and impact resistance. Boron carbide special ceramics are usually made of submicron boron carbide particles as raw materials through a specific sintering process. Therefore, the preparation of submicron boron carbide ceramic particles is very important.

[0003] The common preparation methods of boron carbide ceramic particles can be divided into mechanical crushing and chemical synthesis. When using mechanical crushing to obtain submicron particles by ball milling large-sized boron carbide particles, the following problems exist: (1) Impurities are easily introduced during the crushing process, and subsequent particle size screening is difficult; (2) Particles are prone to cold welding during the ball milling process, forming secondary particle sizes. These particles usually have large hole defects and are difficult to repair through subsequent ball milling processes, which seriously reduces material performance; (3) The operation is cumbersome and the cycle is long, the efficiency is low, and the energy consumption is high. The boron carbide particles obtained by mechanical crushing are mostly pointed. In the subsequent synthesized materials, these sharp shapes often become stress concentration points, which can easily cause material fracture and thus reduce their overall performance. Common chemical synthesis methods include carbon thermal reduction and high-temperature self-propagating synthesis. The carbon thermal reduction method prepares boron carbide particles by reacting a boron source (such as boric acid, borax, sodium boride, etc.) with a carbon source (such as graphite powder, activated carbon, methane, acetylene, etc.) at high temperature, and the cycle is generally 1-3 days. The high-temperature self-propagating synthesis method prepares boron carbide particles through a rapid self-propagating reaction, and the cycle is 1-2 days. The two process methods are time-consuming and energy-intensive to produce submicron boron carbide particles. In addition, during the production process, impurities are easily introduced due to incomplete reaction of raw materials and the washing process of removing reactants in the later stage, which is difficult to remove, thereby seriously reducing the purity of the synthesized submicron boron carbide particles.

[0004] Therefore, a Joule heating rapid preparation method for submicron boron carbide particles needs to be studied urgently. Summary of the invention

[0005] In order to solve the problems of long time and high energy consumption in the existing synthesis method of submicron boron carbide particles, the present invention provides a Joule heating rapid preparation method of submicron boron carbide particles.

[0006] The present invention adopts the following technical solutions to achieve the above-mentioned purpose:

[0007] A Joule heating rapid preparation method for submicron boron carbide particles specifically comprises the following steps:

[0008] 1) Raw material mixing: the boron source and the carbon source are mixed in a certain molar ratio, and the high-energy ball milling method is used to mix the two uniformly;

[0009] 2) Sample loading and vacuum treatment: The mixed powder is loaded into a carbon carrier, the carbon carrier is loaded into a sample holder of a Joule heating device, and an electrode is connected, and the air compressor is turned on to perform vacuum treatment to a certain pressure;

[0010] 3) Heating reaction and sample preparation: Turn on the power of the equipment, set the heating temperature, heating rate and holding time, start heating, wait until the program ends and cools to room temperature, turn on the equipment and take out the sample to obtain submicron boron carbide particles.

[0011] As a preferred solution, the boron source in step 1) is at least one of industrial boron powder, high-purity boron powder or amorphous boron powder, and the average particle size is 500nm to 2μm.

[0012] As a preferred embodiment, the carbon source in step 1) is at least one of graphene or carbon nanotubes.

[0013] As a preferred embodiment, the molar ratio of the boron source to the carbon source in step 1) is (1-10):1.

[0014] As a preferred solution, the vacuum pressure in step 2) is 0.02-0.1 Pa.

[0015] As a preferred solution, the heating temperature in step 3) is 1500-1800°C.

[0016] As a preferred solution, the heating rate in step 3) is 150-180°C / s.

[0017] As a preferred solution, the holding time in step 3) is 30 to 100 seconds.

[0018] The advantages of the present invention compared with the prior art are: utilizing the characteristics of Joule heating technology, by rapidly heating and uniformly heating the raw materials boron source and carbon source, the preparation of submicron boron carbide particles is achieved. Graphene and carbon nanotubes are selected as carbon sources to increase the contact area with the boron source, and the two are evenly mixed by ball milling to ensure sufficient contact and reaction between the boron source and the carbon source. In addition, the advantages of the Joule heating technology, such as fast heating speed and uniform temperature in the sample heating zone, ensure the rapid preparation of submicron boron carbide particles. The preparation method of submicron boron carbide particles provided by the present invention is short in time and low in energy consumption, and can achieve rapid preparation of submicron boron carbide particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a low-magnification scanning image of the submicron boron carbide particles obtained in Example 1.

[0020] Figure 2 This is a high-magnification scan of the submicron boron carbide particles obtained in Example 1.

[0021] Figure 3 This is a scanning image of the submicron boron carbide particles obtained in Example 2. DETAILED DESCRIPTION

[0022] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0023] The Joule heating rapid preparation method of submicron boron carbide particles of the present invention is carried out according to the following steps:

[0024] 1. Mix the boron source and the carbon source in a certain molar ratio, and use a high-energy ball milling method to mix the two evenly.

[0025] The boron powder is one or any combination of industrial boron powder, high-purity boron powder and amorphous boron powder, and the average particle size is 500nm to 2μm.

[0026] The carbon source is graphene and carbon nanotubes or any combination thereof.

[0027] The molar ratio of the boron source to the carbon source is (1-10):1.

[0028] 2. Load the mixed powder obtained in step 1 into a carbon carrier, load the carbon carrier into the sample holder of the Joule heating device, connect the upper electrode, turn on the power of the air compressor to evacuate to a certain pressure.

[0029] The vacuum degree is 0.02~0.1Pa.

[0030] 3. Turn on the power of the equipment, set the heating temperature to 1500-1800℃, the heating rate to 150-180℃ / s, the holding time to 30-100s, start heating, wait for the program to end, cool to room temperature, turn on the equipment and take out the sample, and you can get submicron boron carbide particles.

[0031] Embodiment 1:

[0032] 1. Mix industrial boron powder with an average particle size of 500 nm and graphene in a molar ratio of 2:1, and use high-energy ball milling to mix the two evenly;

[0033] 2. Load the mixed powder obtained in step 1 into a carbon carrier, load the carbon carrier into the sample holder of the Joule heating device, connect the upper electrode, turn on the air compressor power supply to vacuumize until the pressure is 0.1 Pa;

[0034] 3. Turn on the power of the equipment, set the heating temperature to 1800℃, the heating rate to 180℃ / s, and the holding time to 30s, start heating, and wait until the program ends and cools to room temperature, then turn on the equipment and take out the sample to obtain submicron boron carbide particles.

[0035] Embodiment 2:

[0036] 1. Mix industrial boron powder with an average particle size of 1 μm and graphene in a molar ratio of 8:1, and use high-energy ball milling to mix the two evenly;

[0037] 2. Load the mixed powder obtained in step 1 into a carbon carrier, load the carbon carrier into the sample holder of the Joule heating device, connect the upper electrode, turn on the air compressor power supply to vacuumize until the pressure is 0.02Pa;

[0038] 3. Turn on the power of the equipment, set the heating temperature to 1500℃, the heating rate to 150℃ / s, and the holding time to 100s, start heating, and wait until the program ends and cools to room temperature, then turn on the equipment and take out the sample to obtain submicron boron carbide particles.

[0039] Embodiment 3:

[0040] 1. Mix industrial boron powder with an average particle size of 2 μm and graphene in a molar ratio of 5:1, and use high-energy ball milling to mix the two evenly;

[0041] 2. Load the mixed powder obtained in step 1 into a carbon carrier, load the carbon carrier into the sample holder of the Joule heating device, connect the upper electrode, turn on the air compressor power supply to vacuumize until the pressure is 0.05Pa;

[0042] 3. Turn on the power of the equipment, set the heating temperature to 1700℃, the heating rate to 170℃ / s, and the holding time to 50s, start heating, and wait until the program ends and cools to room temperature, then turn on the equipment and take out the sample to obtain submicron boron carbide particles.

[0043] Embodiment 4:

[0044] 1. Mix industrial boron powder with an average particle size of 1.5 μm and graphene in a molar ratio of 2:1, and use high-energy ball milling to mix the two evenly;

[0045] 2. Load the mixed powder obtained in step 1 into a carbon carrier, load the carbon carrier into the sample holder of the Joule heating device, connect the upper electrode, turn on the air compressor power supply to vacuumize until the pressure is 0.02Pa;

[0046] 3. Turn on the power of the equipment, set the heating temperature to 1600℃, the heating rate to 160℃ / s, and the holding time to 80s, start heating, and wait until the program ends and cools to room temperature, then turn on the equipment and take out the sample to obtain submicron boron carbide particles.

[0047] The submicron boron carbide particles obtained in the present invention have a relatively regular shape and a uniform diameter distribution. The morphology of the submicron boron carbide particles obtained in Example 1 is as follows: Figure 1 and Figure 2 As shown. Figure 1 It can be seen that the particle diameter is distributed between 200 and 500 nm. Figure 2 It can be seen that the prepared submicron boron carbide particles have a typical hexagonal structure; the morphology of the submicron boron carbide particles obtained in this embodiment 2 is as follows Figure 3 As shown. Figure 2 It can be seen that the particle diameter is distributed between 550 and 700 nm.

[0048] The present invention and its embodiments are described above, which is not restrictive. The drawings show only one embodiment of the present invention, and the actual steps and operating conditions are not limited thereto. In short, if ordinary technicians in the field are inspired by it and do not deviate from the purpose of the invention, they can creatively design structural methods and embodiments similar to the technical solution, which should all fall within the protection scope of the present invention.

Claims

1. A method for rapidly preparing submicron boron carbide particles by Joule heating, characterized in that: The specific steps include: 1) Raw material mixing: the boron source and the carbon source are mixed in a certain molar ratio, and the high-energy ball milling method is used to mix the two uniformly; 2) Sample loading and vacuum treatment: The mixed powder is loaded into a carbon carrier, the carbon carrier is loaded into a sample holder of a Joule heating device, and an electrode is connected, and the air compressor is turned on to perform vacuum treatment to a certain pressure; 3) Heating reaction and sample preparation: Turn on the power of the equipment, set the heating temperature, heating rate and holding time, start heating, wait until the program ends and cools to room temperature, turn on the equipment and take out the sample to obtain submicron boron carbide particles.

2. The Joule heating rapid preparation method of submicron boron carbide particles according to claim 1, characterized in that: The boron source in step 1) is at least one of industrial boron powder, high-purity boron powder or amorphous boron powder, and the average particle size is 500nm to 2μm.

3. The Joule heating rapid preparation method of submicron boron carbide particles according to claim 1, characterized in that: The carbon source in step 1) is at least one of graphene or carbon nanotubes.

4. The Joule heating rapid preparation method of submicron boron carbide particles according to claim 1, characterized in that: The molar ratio of the boron source to the carbon source in step 1) is (1-10):

1.

5. The Joule heating rapid preparation method of submicron boron carbide particles according to claim 1, characterized in that: The vacuum pressure in step 2) is 0.02-0.1 Pa.

6. The Joule heating rapid preparation method of submicron boron carbide particles according to claim 1, characterized in that: In step 3), the heating temperature is 1500-1800°C.

7. The Joule heating rapid preparation method of submicron boron carbide particles according to claim 1, characterized in that: In step 3), the heating rate is 150-180°C / s.

8. The Joule heating rapid preparation method of submicron boron carbide particles according to claim 1, characterized in that: In step 3), the heat preservation time is 30 to 100 seconds.

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