CN115160023A - A method for preparing boron nitride nanomaterials on the surface of porous ceramic pores - Google Patents

Abstract

The invention discloses a method for preparing a boron nitride nano material on the surface of a porous ceramic pore, which comprises the following steps: 1. mixing boron source raw material powder with metal powder, and performing ball milling to obtain boron source precursor powder; 2. preparing a metal coating on the pore surface of the porous alumina ceramic; 3. and (3) preparing the boron nitride nano material on the pore surfaces of the porous ceramic with the deposited metal coating by high-temperature annealing. According to the invention, the boron nitride nano material grows on the surfaces of the pores of the porous ceramic, so that the specific surface area of the porous ceramic matrix is obviously increased, the porous ceramic matrix has good super-hydrophobic performance, and the characteristics of high temperature resistance and corrosion resistance of the ceramic material are maintained, so that the porous ceramic matrix can be used as a flue gas adsorption filter, sewage treatment, oil-water separation, catalyst carrier and drug carrier in a high-temperature corrosive environment.

Description

A method for preparing boron nitride nanomaterials on the surface of porous ceramic pores

technical field

The invention belongs to the technical field of surface modification of porous ceramics, and particularly relates to a method for preparing boron nitride nanomaterials on the surface of pores of porous ceramics.

Background technique

Ceramic materials have unique application advantages in harsh working conditions due to their corrosion resistance, high temperature resistance and high strength. Porous ceramics have a wide range of practical applications and development prospects in the fields of high temperature (above 800 ℃) flue gas filtration, catalyst support and oil-water separation due to their special properties such as high porosity and high specific surface area. In the above types of applications, the surface condition and specific surface area of the material are often the key factors affecting the performance. Generally, the rougher the surface of the material, the stronger the ability to capture or adsorb fine particles in high-temperature flue gas; the larger the specific surface area of the material, the larger the amount of catalyst that can be supported; the porous ceramic is hydrophobic or oil-modified. , can also be used in the field of oil-water separation, and the larger the specific surface area, the higher the separation efficiency.

Nanomaterials also have a high specific surface area due to their small size. However, it usually exists in the form of powder, which is difficult to handle in actual use. If such materials can be modified on the surface of porous ceramics, the ease of operation will be solved, and at the same time, the advantages of high specific surface area of both can be exploited. Boron nitride is a graphite-like layered ceramic material composed of nitrogen (N) atoms and boron (B) atoms in the form of covalent bonds. It has good high temperature resistance, corrosion resistance, mechanical properties, chemical stability, neutron Absorption and hydrogen storage properties, etc. Common morphologies reported so far include nanospheres, nanoflowers, nanosheets, nanotubes, nanobelts, and nanocorals. Boron nitride nanosheets are petal-like boron nitride nanomaterials, whose thickness is usually less than five nanometers and has a very high specific surface area. Boron nitride nanosheets grown vertically on the surface of the material have excellent superhydrophobic properties. Boron nitride nanotubes are fibrous hollow nanomaterials with a smooth surface. Due to their small nanoscale size, they also have a high specific surface area, and growing vertically on the surface of the material can increase their specific surface area and have good hydrophobic properties. . Nanocoral is a new type of boron nitride nanomaterial with dense nanosheets grown vertically on the surface of nanotubes. Compared with nanotubes, nanocorals have a higher specific surface area due to the existence of a large number of nanosheets on the surface. Also, due to the existence of a large number of nanosheets on the surface, dense nano-scale small protrusions are formed, which increases the surface roughness and makes it have excellent and stable superhydrophobic properties. Growing boron nitride nanomaterials on the surface of porous ceramics can further increase the specific surface area on the basis of maintaining the high temperature resistance and corrosion resistance of the ceramic materials, and change the surface from hydrophilic properties to hydrophobic properties, which can be applied to impurities Adsorption and oil-water separation, especially suitable for complex environments such as acid-base corrosion and high temperature.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a method for preparing boron nitride nanomaterials on the surface of pores of porous ceramics in view of the above-mentioned deficiencies of the prior art. The method promotes the growth of boron nitride nanomaterials on the porous ceramic pore surface by depositing a metal coating on the porous ceramic pore surface, improves the bonding strength of the boron nitride nanomaterial and the porous ceramic pore surface, and avoids the boron nitride nanomaterials. The shedding of the material in a flowing gas flow or liquid flow environment effectively improves the performance of the porous ceramics grown on the surface of the boron nitride nanomaterials and broadens its application range.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present invention is: a method for preparing boron nitride nanomaterials on the surface of porous ceramic pores, characterized in that the method comprises the following steps:

Step 1, preparation of boron source precursor powder: mixing boron source raw material powder with metal powder and then ball milling to obtain boron source precursor powder;

Step 2. Deposition of metal coating: drying the metal chloride to obtain metal chloride powder, and then laying the metal chloride powder on the surface of the porous ceramic placed in the bar-shaped corundum crucible and vibrating until the metal chloride is removed from the porous ceramic. Continue to add metal chloride powder after leaking out of the pores, repeat the vibration process and adding process until the metal chloride powder completely fills the pores of the porous ceramic and covers the surface of the porous ceramic, and then transfers it to a tube furnace to vacuumize and pass H ₂ , heated up to the reduction temperature at a rate of 5°C/min and kept for reduction treatment, cooled to room temperature and then transferred to a high temperature tube furnace, where NH ₃ was introduced at high temperature for homogenization treatment to obtain a uniform distribution of pores on the surface Metal-coated porous ceramics;

Or mix the metal oxide and the thickener to prepare the coating slurry, coat the coating slurry on the porous ceramic until it completely fills the pores of the porous ceramic and covers the surface of the porous ceramic, and then transfer it to a tube furnace after drying. Vacuuming and feeding H ₂ , heating up to the reduction temperature at a rate of 5°C/min and keeping the temperature for reduction treatment to obtain a porous ceramic with metal coating evenly distributed on the pore surface;

Step 3: Preparation of boron nitride nanomaterials: place the boron source precursor powder obtained in step 1 in a square graphite boat, and place the metal coating on the surface of the pores obtained in step 2 in the upper center of the square graphite boat evenly distributed The porous ceramics are covered with graphite paper on the top of the square graphite boat to ensure that the air inlet and air outlet are unobstructed, and then evacuated, and heated to the reaction temperature at a rate of 10°C/min and kept for more than 0.5h. After cooling to room temperature, The white substance obtained on the pore surface of the porous ceramic is the boron nitride nanomaterial; NH ₃ is introduced into the heating and cooling processes.

Aiming at the problems that commonly used metal porous materials have insufficient strength at high temperature (greater than 800°C), poor resistance to strong acid/alkali corrosion, low specific surface area of porous ceramic materials, and difficult manipulation of nanomaterials, the present invention is designed to prepare boron nitride on the surface of porous ceramic pores. nanomaterials. Specifically, in the present application, the metal chloride powder is directly vibrated to fill the pores of the porous ceramic and cover the surface of the porous ceramic, followed by _H2 reduction treatment and _NH3 homogenization treatment, the metal chloride is converted into fine and uniform metal and deposited on the The surface of the porous ceramic includes forming a metal coating on the surface of the pores, or the metal oxide is made into a coating slurry to coat the pores of the porous ceramic and cover the surface of the porous ceramic, and is treated with _H2 reduction and deposited on the porous surface of the porous ceramic. A metal coating is formed; then the boron source precursor powder obtained by mixing the boron source raw material powder and the metal powder by ball milling is placed in a square graphite boat, and a porous ceramic with a metal coating uniformly distributed on the pore surface is placed in the upper center of the square graphite boat, so that the The boron source precursor powder is in a non-contact state with the porous ceramic, and graphite paper is covered on the top of the square graphite boat to gather the reaction gas and ensure the air inlet and outlet are unobstructed. After vacuuming, the temperature rises and ammonia is introduced from the air inlet. The boron source precursor powder is heated and sublimated to form a gas, which reacts with the introduced ammonia gas under the catalytic action of the metal powder: B ₂ O ₃ +2NH ₃ →2BN+3H ₂ O, or 2B+2NH ₃ →2BN+3H ₂ , boron nitride is generated, and the metal coating on the surface of the porous ceramic also plays a synergistic catalytic role, and promotes the growth of boron nitride on its surface to form boron nitride nanomaterials.

In the invention, by depositing a metal coating on the surface of the pores of the porous ceramics, the boron nitride nanomaterials are stably grown on the porous ceramic substrate, and the boron nitride nanomaterials are promoted to grow steadily on the surface of the porous ceramics, thereby improving the relationship between the boron nitride nanomaterials and the porous ceramics. The bonding strength of the pore surface of the porous ceramic prevents the boron nitride nanomaterials from falling off in a flowing air or liquid environment, effectively improves the performance of the porous ceramics grown on the surface of the boron nitride nanomaterials, and broadens its scope of use; at the same time, Both boron nitride nanomaterials and porous ceramics have good high-temperature mechanical properties and corrosion resistance. The two work together to exert their performance advantages, so that the porous ceramics grown on the surface of boron nitride nanomaterials can be applied to higher than metal porous materials. In addition, the present invention grows boron nitride nanomaterials on the pore surface of porous ceramics, and utilizes boron nitride nanomaterials with small size, large specific surface area and excellent hydrophobicity. It makes up for the disadvantage of low specific surface area of porous ceramics, and solves the problem of difficult control during the use of nanomaterial powders, so that the porous ceramics grown on the surface of boron nitride nanomaterials have super-hydrophobic properties and excellent adsorption and filtration performance. Flue gas filtration, oil-water separation, strong acid-base sewage treatment, and catalyst carriers that require high specific surface area under harsh working conditions.

The above-mentioned method for preparing boron nitride nanomaterials on the surface of porous ceramic pores is characterized in that the molar ratio of the boron source raw material powder to the metal powder in step 1 is 1:0.5-1:2, and the boron source The raw material powder is boron oxide or boron powder, and the metal powder is one or more of iron powder, nano iron powder, magnesium powder and nickel powder. The present invention provides boron source and nitrogen source for preparing boron nitride nanomaterials by controlling the type and molar ratio of boron source raw material powder and metal powder in the boron source precursor powder, and the metal powder provides catalysis to ensure the subsequent preparation process. went well.

The above-mentioned method for preparing boron nitride nanomaterials on the surface of porous ceramic pores is characterized in that the time of ball milling in step 1 is more than 0.5h, and the particle size of the boron source precursor powder is 0.5μm～10μm . The present invention ensures sufficient mixing of the boron source raw material powder and the metal powder by controlling the ball milling time; at the same time, due to the different reaction efficiencies of different powders, the present invention effectively improves the boron source precursor by controlling the particle size of the boron source precursor powder. The specific surface area of the powder, thereby improving the efficiency of the subsequent reaction.

The above-mentioned method for preparing boron nitride nanomaterials on the surface of porous ceramic pores is characterized in that, in step 2, the metal chloride is ferric chloride, ferrous chloride or nickel chloride, and the metal oxide is Magnesium oxide. By selecting the above-mentioned metal chlorides or oxides to generate corresponding metal iron, nickel or magnesium coatings, it is beneficial to play a synergistic catalysis effect in the future.

The above-mentioned method for preparing boron nitride nanomaterials on the surface of pores of porous ceramics is characterized in that the porous ceramics in step 2 are porous alumina ceramics or porous zirconia ceramics. The invention adopts porous ceramics with high temperature resistance, corrosion resistance and chemical stability, and utilizes the characteristics of high porosity to increase the growth amount of boron nitride nanomaterials in the subsequent reaction process, thereby improving the surface growth of boron nitride nanomaterials. The adsorption and filtration performance of porous ceramics. The porous ceramics of the present invention can also adopt other high temperature-resistant and corrosion-resistant porous ceramics.

The above-mentioned method for preparing boron nitride nanomaterials on the pore surface of porous ceramics is characterized in that the inflow rate of H in the _second step is 50mL/min～100mL/min, and the reduction temperature of the reduction treatment is 50mL/min～100mL/min 600°C to 800°C, and the temperature of the homogenization treatment is 1100°C to 1300°C. In the present invention, by controlling the inflow rate of _H2 , combined with controlling the reduction temperature to ensure that a metal coating with a suitable thickness is obtained, combined with controlling the temperature of the above-mentioned homogenization treatment, the metal coating is made more fine and uniform, which is helpful to improve the metal coating and porous ceramics. matrix binding force.

The above-mentioned method for preparing boron nitride nanomaterials on the pore surface of porous ceramics is characterized in that the reaction temperature in step 3 is 1100 ℃ ~ 1600 ℃, the holding time is 0.5h ~ 8h, the flow rate of NH ₃ It is 10mL/min～200mL/min. The invention ensures the smooth preparation and generation of boron nitride nanomaterials on the surface of the porous ceramic pores by controlling the reaction temperature and the holding time range, and simultaneously controls the inflow flow of NH ₃ to ensure sufficient reaction with the boron source raw material powder and avoid the inflow flow rate. If it is too high, the resulting boron nitride product is coarse, thereby ensuring the formation of boron nitride nanomaterials.

The above-mentioned method for preparing boron nitride nanomaterials on the pore surface of porous ceramics is characterized in that the morphology of the boron nitride nanomaterials obtained on the pore surfaces of the porous ceramics in step 3 is to grow vertically on the pore surfaces of the porous ceramics of boron nitride nanosheets, nanotubes or nanocorals. In the present invention, the morphology of the product boron nitride nanomaterial is controlled by controlling the reaction temperature or the flow rate of NH ₃ in the reaction process. Specifically, the boron nitride nanosheets, nanotubes, For nano corals, boron nitride nanosheets, nanotubes, and nanocorals are obtained in turn with the flow of NH ₃ from low to high. In the present invention, boron nitride nanomaterials with various shapes are obtained by growing on the pore surface of the porous ceramics. Since the specific surface areas of the boron nitride nanomaterials with different shapes are different, the porous ceramics with the boron nitride nanomaterials grown on the surface are different. The super-hydrophobic performance and adsorption and filtration performance meet the requirements of different fields.

Compared with the prior art, the present invention has the following advantages:

1. The present invention promotes the growth of boron nitride nanomaterials on the porous ceramic pore surface by depositing a metal coating on the porous ceramic pore surface, improves the bonding strength of the boron nitride nanomaterial and the porous ceramic pore surface, and avoids nitridation. The shedding of the boron nanomaterials in the flowing air or liquid flow environment effectively improves the performance of the porous ceramics grown on the surface of the boron nitride nanomaterials, and broadens its application range.

2. The porous ceramic matrix of the present invention and the boron nitride nanomaterial prepared on the surface of its pores have good high-temperature mechanical properties and corrosion resistance, which ensures that the porous ceramics grown on the surface of the boron nitride nanomaterial can be applied to more porous materials than metals. Under higher temperature conditions and strong acid and alkali conditions, its application range has been expanded.

3. The present invention makes up for the disadvantage of low specific surface area of porous ceramics by growing boron nitride nanomaterials on the pore surface of porous ceramics, and makes use of the advantages of small size, large specific surface area and excellent hydrophobicity of boron nitride nanomaterials, and significantly increases the size of porous ceramics. The specific surface area is beneficial to the application in the fields of flue gas filtration, catalyst carrier and so on.

4. Although boron nitride nanomaterials have excellent neutron absorption, adsorption properties and hydrophobic properties, their powdery form makes them inconvenient to use and difficult to recover after adsorbing impurities or oils. Boron nitride nanomaterials grow on the pore surface of porous ceramics, and the porous ceramics are used as the matrix material to facilitate their use, which is conducive to the exertion of the excellent superhydrophobicity and adsorption properties of boron nitride nanomaterials, and can be recycled together with porous ceramics after use. , easy to operate, and solves the problem of difficult control during the use of nanomaterial powders.

5. The present invention uses ball mill activation to prepare boron source precursor powder, combined with tubular furnace reduction, tubular atmosphere protection annealing furnace heating to prepare the target product, the entire process adopts conventional equipment, no special equipment is required, and the method of the present invention is effectively reduced. The preparation difficulty is favorable for industrial production and promotion.

6. The boron source raw material powder, metal powder, metal chloride powder, metal oxide, porous ceramics, hydrogen and ammonia used in the present invention are all conventional common chemical raw materials, which are easy to obtain and further reduce the raw materials of the present invention. Preparation difficulty.

7. The porous ceramic material with boron nitride nanomaterials grown on the pore surface prepared by the present invention has simple and convenient operation, stable and lasting regeneration ability after adsorbing oil substances, and can be reused for many times.

The technical solutions of the present invention will be further described in detail below through the accompanying drawings and embodiments.

Description of drawings

FIG. 1a is a macroscopic topography diagram of the porous alumina ceramic with iron coating uniformly distributed on the pore surface in Example 1 of the present invention.

Figure 1b is a microscopic topography diagram of the porous alumina ceramic with iron coating uniformly distributed on the pore surface in Example 1 of the present invention.

FIG. 2a is a macroscopic topography diagram of the porous alumina ceramic in Example 1 of the present invention.

Fig. 2b is a macroscopic topography diagram of the porous alumina ceramic with boron nitride nanocorals on the pore surface in Example 1 of the present invention.

Figure 3a is a low magnification SEM image of the porous alumina ceramic with boron nitride nanocorals on the pore surface of Example 1 of the present invention.

Figure 3b is an enlarged SEM image of the area shown by the box in Figure 3a.

Figure 3c is an enlarged SEM image of the area shown by the box in Figure 3b.

FIG. 4 is an EDS spectrum of the porous alumina ceramic with boron nitride nanocorals on the pore surface of Example 1 of the present invention.

FIG. 5 is a contact angle diagram of the porous alumina ceramic with boron nitride nanocorals on the pore surface of Example 1 of the present invention and water droplets.

6a is a low magnification SEM image of the porous alumina ceramic with boron nitride nanotubes on the pore surface of Example 4 of the present invention.

Figure 6b is an enlarged SEM image of the area shown by the box in Figure 6a.

Figure 6c is an enlarged SEM image of the boron nitride nanotubes in the region shown by the box in Figure 6b.

FIG. 7 is an EDS spectrum of the porous alumina ceramic with boron nitride nanotubes on the pore surface of Example 4 of the present invention.

8a is a low magnification SEM image of the porous alumina ceramic with boron nitride nanosheets on the pore surface of Example 5 of the present invention.

8b is a medium magnification SEM image of the porous alumina ceramic with boron nitride nanosheets on the pore surface of Example 5 of the present invention.

8c is a high-magnification SEM image of the porous alumina ceramic with boron nitride nanosheets on the pore surface of Example 5 of the present invention.

FIG. 9 is an EDS spectrum of the porous alumina ceramic with boron nitride nanosheets on the pore surface in Example 5 of the present invention.

Detailed ways

Example 1

This embodiment includes the following steps:

Step 1. Preparation of boron source precursor powder: mix boron oxide powder and iron powder in a molar ratio of 1:1 and place it in a ball mill for ball milling for 2 hours to obtain boron source precursor powder with a particle size of 0.5 μm to 10 μm;

Step 2. Deposition of metal coating: ferric chloride trihydrate was dried in an oven at 120° C. for 8 hours to obtain ferrous chloride powder, and then the ferrous chloride powder was placed on a porous alumina ceramic placed in a bar-shaped corundum crucible. The surface is vibrated until the ferrous chloride powder leaks from the pores of the porous alumina ceramic, and the ferrous chloride powder is continued to be added, and the vibration process and the adding process are repeated until the ferrous chloride powder is completely filled with the porous alumina ceramic. Pores and cover the surface of porous alumina ceramics, then transferred to a tube furnace to vacuumize and pass in H ₂ at a flow rate of 50 mL/min, heat up to 600 ° C at a rate of ₅ ° C/min and keep for 1 h Carry out reduction treatment, continue to transfer to a high-temperature tube furnace after cooling to room temperature, and pass NH ₃ at 1100 ° C for homogenization treatment to obtain porous alumina ceramics with iron coating uniformly distributed on the pore surface;

Step 3. Preparation of boron nitride nanomaterials: place the boron source precursor powder obtained in step 1 in a square graphite boat, and place the iron coating on the surface of the pores obtained in step 2 in the upper center of the square graphite boat. The porous alumina ceramic is made of porous alumina, and the graphite paper is covered on the top _of the square graphite boat to ensure that the air inlet and outlet are unobstructed, and then evacuated and introduced into NH ₃ . The rate of heating was raised to 1400 °C and kept for 1 h, and ammonia was continued to cool to room temperature. The flow rate of NH ₃ was 50 mL/min. The white substance obtained on the surface of the pores of the porous alumina ceramic was boron nitride nanomaterials, forming Porous alumina ceramics with boron nitride nanomaterials on the pore surface.

Fig. 1a and Fig. 1b are respectively the macroscopic and micro-morphological diagrams of the porous alumina ceramic with iron coating uniformly distributed on the pore surface of the present embodiment. Combining with Fig. 1a and Fig. 1b, it can be seen that the porous alumina ceramic with iron coating uniformly distributed on the pore surface The overall appearance of the ceramic is black-gray, and the pore surface of the porous alumina ceramic is covered with a large number of spherical iron particles.

Fig. 2a is a macro-morphological diagram of the porous alumina ceramic in this embodiment, and Fig. 2b is a macro-morphological diagram of the porous alumina ceramic with boron nitride nanocorals on the pore surface of this embodiment. Combining Fig. 1a and Fig. 1b, we can see that , after being prepared by the method of this embodiment, a large amount of white fluffy substances appear on the surface of the porous alumina ceramics.

Fig. 3a is a low magnification SEM image of the porous alumina ceramic with boron nitride nanomaterials on the pore surface of this embodiment, Fig. 3b is an enlarged SEM image of the area shown in the box in Fig. 3a, Fig. 3c is the area shown in the box in Fig. 3b The enlarged SEM image of the area, Figure 4 is the EDS energy spectrum of the porous alumina ceramic with boron nitride nanocoral on the pore surface of this embodiment. Combining with Figures 3a to 3c and Figure 4, it can be seen that the porous alumina in this embodiment A large number of white fluffy substances appearing on the surface of the ceramic are boron nitride nanofiber structures, and there are a large number of nanosheets vertically on the surface of the fibrous structure, and the appearance is exactly like coral, indicating that this example is prepared on the surface of porous ceramics including pore surfaces. Boron nitride nanocorals growing vertically on the surface.

Fig. 5 is a contact angle diagram of the porous alumina ceramic with boron nitride nanocoral on the pore surface of this embodiment and water droplets. It can be seen from Fig. 5 that the contact angle is 139°, indicating that the pore surface in this embodiment has nitrogen The porous alumina ceramics of boron oxide nanomaterials exhibit excellent superhydrophobic properties.

The metal powder in this embodiment can also be replaced with one or more of iron powder, nano-iron powder, magnesium powder and nickel powder other than iron powder.

Example 2

The difference between this example and Example 1 is that the reaction temperature in step 3 is 1600°C.

After testing, in this example, a large number of dense boron nitride nanocorals grown vertically on the pore surface of porous ceramics were prepared on the pore surface of porous alumina ceramics. The diameter of the coral increases in size.

Example 3

The difference between this example and Example 1 is that the reaction temperature in step 3 is 1350°C.

After testing, in this example, a large number of dense boron nitride nanocorals grown vertically on the pore surface of porous ceramics were prepared on the pore surface of porous alumina ceramics. The diameter of the corals decreased in size.

Example 4

The difference between this example and Example 1 is that the reaction temperature in step 3 is 1300°C.

Fig. 6a is a low magnification SEM image of the porous alumina ceramic with boron nitride nanotubes on the pore surface of this embodiment, Fig. 6b is an enlarged SEM image of the area shown by the box in Fig. 6a, Fig. 6c is the area shown by the box in Fig. 6b The enlarged SEM image of the regional boron nitride nanotubes, FIG. 7 is the EDS energy spectrum of the porous alumina ceramics with boron nitride nanotubes on the pore surface of this embodiment. Combining with FIGS. 6a to 6c and FIG. In the example, a large number of dense boron nitride nanotubes grown vertically on the pore surface of the porous ceramic were prepared on the pore surface of the porous ceramic.

Example 5

The difference between this example and Example 1 is that the reaction temperature in step 3 is 1200°C.

Fig. 8a is a low magnification SEM image of the porous alumina ceramic with boron nitride nanosheets on the pore surface of this embodiment, and Fig. 8b is a medium magnification SEM image of the porous alumina ceramics with boron nitride nanosheets on the pore surface of this embodiment Fig. 8c is a high magnification SEM image of the porous alumina ceramic with boron nitride nanosheets on the pore surface of this example, Fig. 9 is the EDS energy of the porous alumina ceramic with boron nitride nanosheets on the pore surface of this example From the spectrum, it can be seen in combination with FIGS. 8 a to 8 c and FIG. 9 that in this example, a large number of dense boron nitride nanosheets grown vertically on the pore surface of the porous ceramic were prepared on the pore surface of the porous ceramic.

Example 6

The difference between this example and Example 1 is that the reaction temperature in step 3 is 1100°C.

After testing, in this example, a large number of dense boron nitride nanosheets grown vertically on the pore surface of the porous ceramic are prepared on the pore surface of the porous alumina ceramic.

Example 7

The difference between this example and Example 1 is: in step 3, the flow rate of ammonia gas is 10 mL/min.

After testing, in this example, a large number of dense boron nitride nanosheets grown vertically on the pore surface of the porous ceramic are prepared on the pore surface of the porous alumina ceramic.

Example 8

The difference between this embodiment and Embodiment 1 is: in step 3, the flow rate of ammonia gas is 200 mL/min.

After testing, in this example, a large number of dense boron nitride nanocorals grown vertically on the pore surface of porous ceramics were prepared on the pore surface of porous alumina ceramics. Corals are slightly larger in diameter.

Example 9

The difference between this example and Example 1 is that the ball milling time is 0.5h.

After testing, in this example, a large number of dense boron nitride nanocorals grown vertically on the surface of the pores of the porous ceramics were prepared on the surface of the pores of the porous alumina ceramics.

Example 10

The difference between this example and Example 1 is that the ball milling time is 4h.

After testing, in this example, a large number of dense boron nitride nanocorals grown vertically on the surface of the pores of the porous ceramics were prepared on the surface of the pores of the porous alumina ceramics.

Example 11

The difference between this example and Example 1 is that the ball milling time is 12h.

After testing, in this example, a large number of dense boron nitride nanocorals grown vertically on the surface of the pores of the porous ceramics were prepared on the surface of the pores of the porous alumina ceramics.

Example 12

The difference between this example and Example 1 is that the holding time of the reaction in step 3 is 0.5h.

After testing, in this example, a large number of boron nitride nanotubes with smooth surface were prepared on the pore surface of porous alumina ceramics, and the diameter was smaller than that of Example 1. The reaction time of the embodiment is short, and most of the nanotubes have not yet grown into boron nitride nanocorals with dense nanosheets growing on the surface.

Example 13

The difference between this example and Example 1 is that the holding time of the reaction in step 3 is 2h.

After testing, in this example, a large number of dense boron nitride nanocorals grown vertically on the pore surface of porous ceramics were prepared on the pore surface of porous alumina ceramics.

Example 14

The difference between this example and Example 1 is: the holding time of the reaction in step 3 is 8h.

After testing, in this example, a large number of dense boron nitride nanocorals grown vertically on the pore surface of porous ceramics were prepared on the pore surface of porous alumina ceramics.

Example 15

The difference between this example and Example 1 is: in step 1, the boron oxide powder and the iron powder are mixed in a molar ratio of 1:0.5.

After testing, in this example, a large number of dense boron nitride nanocorals grown vertically on the surface of the pores of the porous ceramics were prepared on the surface of the pores of the porous alumina ceramics.

Example 16

The difference between this example and Example 1 is that: in step 1, the boron oxide powder and the iron powder are mixed in a molar ratio of 1:2.

After testing, in this example, a large number of dense boron nitride nanocorals grown vertically on the surface of the pores of the porous ceramics were prepared on the surface of the pores of the porous alumina ceramics.

Example 17

The difference between this embodiment and Embodiment 1 is: in step 1, the metal powder is magnesium powder and iron powder, and the boron oxide powder is mixed with magnesium powder and iron powder in a molar ratio of 2:0.5:1.

After testing, in this example, a large number of dense boron nitride nanocorals grown vertically on the surface of the pores of the porous ceramics were prepared on the surface of the pores of the porous alumina ceramics.

Example 18

The difference between this example and Example 1 is: in step 1, the metal powder is magnesium powder and iron powder, and the boron oxide powder is mixed with magnesium powder and iron powder in a molar ratio of 2:1:1.

After testing, in this example, a large number of dense boron nitride nanocorals grown vertically on the surface of the pores of the porous ceramics were prepared on the surface of the pores of the porous alumina ceramics.

Example 19

The difference between this embodiment and Embodiment 1 is that in step 1, the boron source raw material powder is boron powder, and the metal powder is nano iron powder.

After testing, in this example, a large number of dense boron nitride nanocorals grown vertically on the surface of the pores of the porous ceramics were prepared on the surface of the pores of the porous alumina ceramics.

Example 20

The difference between this embodiment and Embodiment 1 is that in step 1, the boron source raw material powder is boron powder, and the metal powder is nickel powder.

After testing, in this example, a large number of dense boron nitride nanocorals grown vertically on the surface of the pores of the porous ceramics were prepared on the surface of the pores of the porous alumina ceramics.

Example 21

The difference between this example and Example 1 is: in step 2, the flow rate of H ₂ is 100 mL/min.

After testing, in this example, a large number of dense boron nitride nanocorals grown vertically on the pore surface of the porous ceramic were prepared on the pore surface of the porous alumina ceramic, and the morphology and structure were the same as those in Example 1.

Example 22

The difference between this example and Example 1 is that the metal chloride in step 2 is ferric chloride, the temperature of the reduction treatment is 800°C, and the temperature of the homogenization treatment is 1300°C.

After testing, in the second step of this example, the spherical iron particles covered on the pore surface of the porous alumina ceramic are more coarse, and in this example, more ferrous particles that grow vertically on the pore surface of the porous alumina ceramic are prepared on the pore surface of the porous alumina ceramic. Massive dense boron nitride nanocorals.

Example 23

The difference between this embodiment and embodiment 1 is: the metal chloride in step 2 is nickel chloride.

After testing, in the second step of this example, the pore surface of the porous alumina ceramic is covered with a nickel coating with fine particles, and a large amount of dense nitrogen that grows vertically on the pore surface of the porous alumina ceramic is prepared on the pore surface of the porous alumina ceramic in this example. Boronide Nanocoral.

Example 24

The difference between this example and Example 1 is that the deposition process of the metal coating in step 2 is: mixing gold magnesium oxide and thickener PVA to prepare a coating slurry, and coating the coating slurry on the porous oxide layer. On the aluminum ceramics until the pores of the porous alumina ceramics are completely filled and the surface of the porous ceramics is covered. After drying, it is transferred to a tube furnace to be evacuated and _fed with H ₂ . The temperature was raised to 600 °C at a rate of min and kept for 1 h for reduction treatment to obtain porous alumina ceramics with a magnesium coating uniformly distributed on the pore surface.

After testing, in the second step of this example, the pore surface of the porous alumina ceramic is covered with a fine-grained magnesium coating, and a large amount of dense nitrogen that grows vertically on the pore surface of the porous alumina ceramic is prepared on the pore surface of the porous alumina ceramic in this example. Boronide Nanocoral.

Example 25

The difference between this embodiment and Embodiment 1 is that the porous ceramics are porous zirconia ceramics.

After testing, in this example, a large number of dense boron nitride nanocorals grown vertically on the pore surface of the porous zirconia ceramic were prepared on the pore surface of the porous zirconia ceramic.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any way. Any simple modifications, changes and equivalent changes made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solutions of the present invention.

Claims (8)

1. a method for preparing boron nitride nanomaterial on porous ceramic pore surface, is characterized in that, this method comprises the following steps: Step 1, preparation of boron source precursor powder: mixing boron source raw material powder with metal powder and then ball milling to obtain boron source precursor powder; Step 2. Deposition of metal coating: drying the metal chloride to obtain metal chloride powder, and then laying the metal chloride powder on the surface of the porous ceramic placed in the bar-shaped corundum crucible and vibrating until the metal chloride is removed from the porous ceramic. Continue to add metal chloride powder after leaking out of the pores, repeat the vibration process and adding process until the metal chloride powder completely fills the pores of the porous ceramic and covers the surface of the porous ceramic, and then transfers it to a tube furnace to vacuumize and pass H ₂ , heated up to the reduction temperature at a rate of 5°C/min and kept for reduction treatment, cooled to room temperature and then transferred to a high temperature tube furnace, where NH ₃ was introduced at high temperature for homogenization treatment to obtain a uniform distribution of pores on the surface Metal-coated porous ceramics; Or mix the metal oxide and the thickener to prepare the coating slurry, coat the coating slurry on the porous ceramic until it completely fills the pores of the porous ceramic and covers the surface of the porous ceramic, and then transfer it to a tube furnace after drying. Vacuuming and feeding H ₂ , heating up to the reduction temperature at a rate of 5°C/min and keeping the temperature for reduction treatment to obtain a porous ceramic with metal coating evenly distributed on the pore surface; Step 3: Preparation of boron nitride nanomaterials: place the boron source precursor powder obtained in step 1 in a square graphite boat, and place the metal coating on the surface of the pores obtained in step 2 in the upper center of the square graphite boat evenly distributed The porous ceramics are covered with graphite paper on the top of the square graphite boat to ensure that the air inlet and air outlet are unobstructed, and then evacuated, and heated to the reaction temperature at a rate of 10°C/min and kept for more than 0.5h. After cooling to room temperature, The white substance obtained on the pore surface of the porous ceramic is the boron nitride nanomaterial; NH ₃ is introduced into the heating and cooling processes. 2 . The method for preparing boron nitride nanomaterials on the surface of porous ceramic pores according to claim 1 , wherein the molar ratio of the boron source raw material powder to the metal powder in step 1 is 1:0.5-1 : 2, the boron source raw material powder is boron oxide or boron powder, and the metal powder is one or more of iron powder, nano-iron powder, magnesium powder and nickel powder. 3. The method for preparing boron nitride nanomaterials on the pore surface of porous ceramics according to claim 1, wherein in step 1, the ball milling time is more than 0.5h, and the boron source precursor powder is The particle size is 0.5 μm to 10 μm. 4. a kind of method for preparing boron nitride nanomaterial on porous ceramic pore surface according to claim 1, is characterized in that, the metal chloride described in step 2 is ferric chloride, ferrous chloride or nickel chloride , the metal oxide is magnesium oxide. 5 . The method for preparing boron nitride nanomaterials on the pore surface of porous ceramics according to claim 1 , wherein the porous ceramics in step 2 are porous alumina ceramics or porous zirconia ceramics. 6 . 6 . The method for preparing boron nitride nanomaterials on the surface of porous ceramic pores according to claim 1 , wherein the flow rate of H in step ₂ is 50mL/min～100mL/min, The reduction temperature of the reduction treatment is all 600°C to 800°C, and the temperature of the homogenization treatment is 1100°C to 1300°C. 7 . The method for preparing boron nitride nanomaterials on the pore surface of porous ceramics according to claim 1 , wherein the reaction temperature in step 3 is 1100° C.～1600° C., and the holding time is 0.5h～8h. 8 . , the flow rate of NH ₃ is 10mL/min～200mL/min. 8 . The method for preparing boron nitride nanomaterials on the pore surface of porous ceramics according to claim 1 , wherein the morphology of the boron nitride nanomaterials obtained on the pore surfaces of the porous ceramics described in step 3 is: 8 . Boron nitride nanosheets, nanotubes or nanocorals grown vertically on the pore surface of porous ceramics.

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