阅读说明：本技术 一种低反应活性的无机氮化硼粉体及其制备方法 (Inorganic boron nitride powder with low reactivity and preparation method thereof ) 是由 彭喆 柴笑笑 李松 高龙飞 安楠 于 2021-10-28 设计创作，主要内容包括：本发明涉及无机材料技术领域,尤其是涉及一种低反应活性的无机氮化硼粉体及其制备方法。包括如下步骤：将环硼氮烷加入到高压釜中,通入惰性气体,升压至1-5MPa;升压后,第一次升温至100-150℃,保温0.5-6h；第二次升温至150-200℃,保温0.5-3h,获得固体产物；将固体产物粉碎,细化后获得低反应活性的无机氮化硼粉体；通过低反应活性的无机氮化硼粉体的制备方法的设计以解决现有技术中存在的制备无机氮化硼粉体,需要在高温条件获得,对设备等要求高,同时,获得的无机氮化硼粉体气孔率低,疏松程度和反应活性适中的技术问题。(The invention relates to the technical field of inorganic materials, in particular to inorganic boron nitride powder with low reactivity and a preparation method thereof. The method comprises the following steps: adding borazine into a high-pressure kettle, introducing inert gas, boosting the pressure to 1-5MPa, raising the temperature to 100-150 ℃ for the first time after boosting, and preserving the temperature for 0.5-6 h; the temperature is raised to 150 ℃ and 200 ℃ for the second time, and the temperature is kept for 0.5 to 3 hours to obtain a solid product; crushing and refining the solid product to obtain inorganic boron nitride powder with low reaction activity; the method for preparing the inorganic boron nitride powder with low reactivity is designed to solve the technical problems that the inorganic boron nitride powder prepared in the prior art needs to be obtained under a high-temperature condition and has high requirements on equipment and the like, and meanwhile, the obtained inorganic boron nitride powder has low porosity and moderate porosity and reactivity.)

1. A preparation method of inorganic boron nitride powder with low reactivity is characterized by comprising the following steps: the method comprises the following steps:

adding borazine into a high-pressure kettle, introducing inert gas, boosting to 1-5MPa, heating to 175 ℃ for the first time after boosting, and keeping the temperature for the first time for 3.5-6 h; the temperature is raised to 125-200 ℃ for the second time, and the second heat preservation time is 0.5-3h, so as to obtain a solid product;

and crushing and refining the solid product to obtain the inorganic boron nitride powder with low reaction activity.

2. The method according to claim 1, wherein the method comprises the steps of: the inert gas includes at least one of nitrogen and argon.

3. The method for preparing the inorganic boron nitride powder with low reactivity according to claim 2, wherein: the inert gas is argon.

4. The method according to claim 3, wherein the method comprises the steps of: temperature T of first temperature rise₁Temperature T corresponding to the second temperature rise₂Satisfy T₂=T₁+25。

5. The method for preparing the inorganic boron nitride powder with low reactivity according to claim 4, wherein: first heat preservation time t₁And the second heat preservation time t₂Satisfy t₁=t₂+3。

6. The method for preparing the inorganic boron nitride powder with low reactivity according to claim 5, wherein: introducing argon, and boosting the pressure to 3MPa; the temperature is increased to 125 ℃ for the first time, and the temperature is kept for 6 hours; the temperature is raised to 150 ℃ for the second time, and the temperature is kept for 3 hours.

7. The method according to claim 6, wherein the method comprises the steps of: before borazine was added to the autoclave, borazine was placed in a stainless steel container and then in the autoclave.

8. The method according to claim 7, wherein the method comprises the steps of: the conditions for refining the inorganic boron nitride powder by the ball mill are as follows: the rotating speed is 240-; the grain size of the inorganic boron nitride powder after thinning is 0.2 to 1 mu m.

9. The method according to claim 8, wherein the method comprises the steps of: the molecular ion peak of borazine GCMS is 80, the chromatographic separation retention time is 2min, and the unimodal area is more than or equal to 99%.

10. A low-reactivity inorganic boron nitride powder produced based on the method for producing a low-reactivity inorganic boron nitride powder according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of inorganic materials, in particular to inorganic boron nitride powder with low reactivity and a preparation method thereof.

Background

The hexagonal boron nitride (h-BN) has a hexagonal layered structure similar to graphite, is commonly called white graphite, has excellent dielectric property and chemical stability, and can be used for preparing products or parts such as h-BN ceramics, c-BN ceramics, h-BN ceramic antenna housings, h-BN ceramic microwave tube energy transmission windows, clamping rod materials and the like. The common preparation methods of the hexagonal boron nitride ceramic include pressureless sintering, hot-pressing sintering, reaction sintering, self-propagating method and CVD method, and the raw materials used in the methods are boron nitride ceramic powder, boron powder, boric acid, ammonia gas, borazine and the like. The boron nitride ceramic powder, the boron powder, the boric acid and the ammonia gas have stable performance at normal temperature and normal pressure, and the hexagonal boron nitride ceramic needs to be prepared under the conditions of ultrahigh temperature and ultrahigh pressure; borazine is a high-activity, low-viscosity and volatile liquid boron nitride ceramic precursor, and is often used for preparing boron nitride ceramics or boron nitride-based composite materials in complex operation steps and special tooling equipment. At present, starting from the characteristic of high reactivity of borazine, the reactivity of borazine is reduced, and the research and preparation of low-reactivity inorganic boron nitride powder are a new development direction.

The national defense Kodali Junsheng reports a method for preparing borazine polymers with different molecular weights and shapes by borazine crosslinking polymerization, wherein the reaction temperature is 70-90 ℃, the reaction time is 12-20h, amorphous boron nitride ceramics can be obtained by the borazine polymer at 1000 ℃, and hexagonal desalt boron ceramics can be obtained at 1500 ℃. However, the method gradually decreases the compactness of the borazine polymer with the increase of the temperature, and the pores of the material gradually become larger, which is not favorable for preparing the densified material, and meanwhile, the method has longer reaction time and is not favorable for industrial application. The inventors of bamboo Tianhao et al invented a preparation method of boron nitride powder by using boron carbide as raw material and adopting the procedures of high temperature (1800 ℃) and high pressure (0.6 MPa), twice roasting and oxidizing, etc., the method needs high temperature and high pressure environment, the equipment requirement is high, the preparation process is various, and the prepared boron nitride powder is inactive inorganic boron nitride powder, and is not favorable for being used as an additive of a chemically grafted modified polymer. Borazine has high reaction activity, and when the temperature exceeds 70 ℃, the molecules are polymerized through a large amount of boron hydrogen bond (B-H)/nitrogen hydrogen bond (N-H) reactions to form a white solid polymer. Therefore, under the conditions of vacuum pumping and 70 ℃, borazine needs more than 48 hours to be converted into solid polyborazine by the Fazen, P.J. and other methods, which is not beneficial to industrial utilization, and the yield of the solid polyborazine is lower than that of the invention. In the method of Lijunsheng et al, the temperature is raised to 90 ℃ for 18h to obtain solid polyborazine, and meanwhile, the material has high porosity, serious foaming phenomenon and increased porosity.

Therefore, in view of the above problems, the present invention is urgently needed to provide a method for preparing an inorganic boron nitride powder with low reactivity.

Disclosure of Invention

The invention aims to provide a preparation method of low-reactivity inorganic boron nitride powder, which solves the technical problems that the inorganic boron nitride powder needs to be obtained under a high-temperature condition and has high requirements on equipment and the like, and the obtained inorganic boron nitride powder has low porosity and moderate porosity and reactivity in the prior art through the design of the preparation method of the low-reactivity inorganic boron nitride powder.

The invention provides a preparation method of inorganic boron nitride powder with low reactivity, which comprises the following steps:

adding borazine into a high-pressure kettle, introducing inert gas, boosting to 1-5MPa, heating to 175 ℃ for the first time after boosting, and keeping the temperature for the first time for 3.5-6 h; the temperature is raised to 125-200 ℃ for the second time, and the second heat preservation time is 0.5-3h, so as to obtain a solid product;

and crushing and refining the solid product to obtain the inorganic boron nitride powder with low reaction activity.

Preferably, the inert gas comprises at least one of nitrogen and argon.

Preferably, the inert gas is argon.

Preferably, the temperature T of the first temperature rise₁Temperature T corresponding to the second temperature rise₂Satisfy T₂=T₁+25。

Preferably, the first incubation time t₁Second heat preservation time t₂Satisfy t₁=t₂+3

Preferably, argon is introduced, and the pressure is increased to 3MPa; the temperature is increased to 125 ℃ for the first time, and the temperature is kept for 6 hours; the temperature is raised to 150 ℃ for the second time, and the temperature is kept for 3 hours.

Preferably, borazine is placed in a stainless steel container prior to being added to the autoclave.

Preferably, the conditions for refining the inorganic boron nitride powder by the ball mill are as follows: the rotating speed is 240-; the grain size of the inorganic boron nitride powder after thinning is 0.2 to 1 mu m.

Preferably, the molecular ion peak of borazine GCMS is 80, the chromatographic separation retention time is 2min, and the unimodal area is more than or equal to 99%.

The invention also provides the low-reactivity inorganic boron nitride powder prepared by the preparation method of the low-reactivity inorganic boron nitride powder.

Compared with the prior art, the preparation method of the inorganic boron nitride powder with low reactivity provided by the invention has the following steps:

1. according to the preparation method of the inorganic boron nitride powder with low reactivity, provided by the invention, by oxygen isolation and pressurization, the generated hydrogen is ensured to be uniform and stable when overflowing the solidified body material (low-activity inorganic boron nitride powder) in the heating process of borazine, the compactness of the solid low-activity inorganic boron nitride powder is ensured, meanwhile, the yield of the solidified low-activity inorganic boron nitride powder is improved, and the volatilization loss is reduced.

2. The preparation method of the inorganic boron nitride powder with low reactivity provided by the invention adopts two temperature rises, the first temperature rise is 100-150 ℃, and the liquid borazine is converted into the solid polyborazine in a short time, so that the curing time is reduced, and the engineering use is facilitated; the second time, the solid polyborozine is converted into inorganic boron nitride powder with low activity in a short time at the temperature of 150-200 ℃.

3. Compared with the prior art, the low-activity inorganic boron nitride powder prepared by the method has the advantages that the operation process is gradually changed, the material texture is uniform and compact, the preparation time is greatly shortened, and the low-activity inorganic boron nitride powder is beneficial to engineering application.

4. The low-reactivity inorganic boron nitride powder prepared by the preparation method contains a small amount of B-H bonds or N-H bonds on the surface, and can be used as a reactive site to be added into materials such as resin, rubber, ceramics, glass and the like to be used as a functional filler.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is an IR spectrum of example one;

FIG. 2 is an IR spectrum of example two;

FIG. 3 is an IR spectrum of example III.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides

A preparation method of inorganic boron nitride powder with low reactivity comprises the following steps:

s1) adding borazine into a high-pressure kettle, introducing inert gas, boosting to 1-5MPa, raising the temperature to 175 ℃ for the first time after boosting, and keeping the temperature for the first time for 3.5-6 h; the temperature is raised to 125-200 ℃ for the second time, and the second heat preservation time is 0.5-3h, so as to obtain a solid product;

s2) crushing the solid product, and refining to obtain the inorganic boron nitride powder with low reaction activity.

Specifically, the inert gas includes at least one of nitrogen and argon.

Specifically, the inert gas is argon.

Specifically, the temperature T of the first temperature rise₁Temperature T corresponding to the second temperature rise₂Satisfy T₂=T₁+25。

Specifically, the first heat-preservation time t₁And the second heat preservation time t₂Satisfy t₁=t₂+3

Specifically, argon is introduced, and the pressure is increased to 3MPa; the temperature is increased to 125 ℃ for the first time, and the temperature is kept for 6 hours; the temperature is raised to 150 ℃ for the second time, and the temperature is kept for 3 hours.

Specifically, before borazine was added to the autoclave, borazine was placed in a stainless steel container and then placed in the autoclave.

Specifically, the conditions for refining the inorganic boron nitride powder by the ball mill are as follows: the rotating speed is 240-; the grain size of the inorganic boron nitride powder after thinning is 0.2 to 1 mu m.

Specifically, the molecular ion peak of borazine GCMS is 80, the chromatographic separation retention time is 2min, and the unimodal area is more than or equal to 99%.

According to the preparation method of the inorganic boron nitride powder with low reaction activity, provided by the invention, borazine is polymerized to form solid polyborazine with certain B-H and N-H activities under high pressure and a first heating condition, and hydrogen generated by polymerization is uniformly released; under the conditions of high pressure and secondary heating, the solid polyborosilazane with certain B-H and N-H activity continuously undergoes dehydrogenation polymerization reaction to form low-activity inorganic boron nitride powder with a small amount of B-H and N-H.

Example one

The preparation of sample 1 (inorganic boron nitride powder with low reactivity) comprises the following steps:

adding 2kg of borazine into a high-pressure kettle, introducing nitrogen, boosting the pressure to 1MPa, raising the temperature to 175 ℃ for the first time after boosting, and preserving the temperature for 6 hours; heating to 200 ℃ for the second time, and preserving heat for 3 hours to obtain a solid product;

and crushing and refining the solid product to obtain inorganic boron nitride powder with low reaction activity, namely a sample 1.

The yield of sample 1 was 1.85kg, 92.6%.

Sample 1 was pulverized and then subjected to infrared scanning, and as shown in FIG. 1, the infrared spectrum of sample 1 showed the presence of B-H and N-H stretching vibration peaks having small peak areas with weak absorption, but at 1350cm^-1The strong and large-area absorption peak of the sample 1 is the stretching vibration peak of B-N, and the comparison of the two shows that the main structure of the sample 1 is B-N and a small amount of B-H and N-H exist.

Preparation of comparative example 1

The difference between the comparative example 1 and the sample 1 is that the yield of the obtained inorganic boron nitride powder is 0.723g, the yield is 36 percent, and the boron nitride powder is not compact, wherein the temperature is raised to 200 ℃ at one time under normal pressure under the condition of introducing nitrogen.

Example 2

The preparation of sample 2 (inorganic boron nitride powder with low reactivity) comprises the following steps:

4kg of borazine is placed in a stainless steel iron box and then placed in a high-pressure kettle, nitrogen is introduced, the pressure is increased to 3MPa, and after the pressure is increased, the temperature is increased to 125 ℃ for the first time, and the temperature is kept for 6 hours; heating to 150 ℃ for the second time, and preserving heat for 3 hours to obtain a solid product;

and crushing and refining the solid product to obtain inorganic boron nitride powder with low reaction activity, namely a sample 2.

The yield of sample 2 was 3.72kg, 93.1%.

Sample 2 was pulverized and then subjected to infrared scanning, and as shown in FIG. 2, the infrared spectrum of sample 2 showed the presence of B-H and N-H stretching vibration peaks having small peak areas with weak absorption, but at 1350cm^-1The strong and large-area absorption peak of the sample 2 is a B-N stretching vibration peak, and the comparison of the two shows that the main structure of the sample is B-N and a small amount of B-H and N-H exist.

Preparation of comparative example 2

Comparative example 2 differs from sample 2 only in that the elevated pressure is raised to 125 ℃ for 6 h.

The borazine yield of comparative example 2 was 3.6kg, the yield was 90.1%, the inorganic boron nitride powder had more B-H and N-H, and the activity was higher.

Example 3

The preparation of sample 3 (inorganic boron nitride powder with low reactivity) comprises the following steps:

placing 3kg of borazine in a stainless steel iron box, placing in a high-pressure kettle again, introducing nitrogen and argon, wherein the volume ratio of the nitrogen to the argon is 1:1, and increasing the pressure to 5MPa, and then, increasing the pressure, firstly increasing the temperature to 150 ℃, and preserving the heat for 4.5 hours; raising the temperature to 175 ℃ for the second time, and preserving the temperature for 1.5 hours to obtain a solid product;

and crushing and refining the solid product to obtain inorganic boron nitride powder with low reaction activity, namely a sample 2.

The yield of sample 3 was 2.79kg, 92.9%.

Sample 3 was ground to a powder and after grinding, an infrared scan was performed, as shown in fig. 3, to find that a small amount of B-H and N-H was present in sample 3 (see example 1 for analysis).

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.