CN111925658B

CN111925658B - In-situ foaming process for preparing thin-layer carbon-loaded nano silicon dioxide material

Info

Publication number: CN111925658B
Application number: CN202010815262.9A
Authority: CN
Inventors: 丁春艳; 吴松松; 李英杰; 吴赟
Original assignee: Shandong University of Technology
Current assignee: Shandong University of Technology
Priority date: 2020-08-14
Filing date: 2020-08-14
Publication date: 2022-07-15
Anticipated expiration: 2040-08-14
Also published as: CN111925658A

Abstract

The invention discloses an in-situ foaming process for preparing thin-layer carbon-loaded nano SiO2 composite materials in batches, which comprises the following steps: dissolving glucose and SiO2 (200 nm) in deionized water, carrying out ultrasonic treatment for five minutes to form a uniform solution, dropwise adding the uniform solution into an ammonium nitrate solution, heating and stirring to obtain a mixed solution, putting the mixed solution into a forced air drying oven to react for 7 hours at 120 ℃ to obtain a precursor, and carrying out heat treatment at 700 ℃ to obtain the thin-layer carbon-loaded nano SiO2 composite material. The method belongs to the field of chemical raw material production, and the wave-absorbing material prepared by the method has the advantages of light weight, wide frequency (7.1 GHz), super-strong absorption (-47.7 dB), low density, batch preparation and the like, and can be applied to the field of wave absorption on a large scale.

Description

In-situ foaming process for preparing thin-layer carbon-loaded nano silicon dioxide material

Technical Field

The invention provides an in-situ foaming process for preparing thin-layer carbon-loaded nano silicon dioxide materials in batches, and belongs to the field of preparation of novel wave-absorbing materials.

Background

The rapid development of the electronic industry, a series of electromagnetic pollution problems such as electromagnetic radiation, electromagnetic interference and the like are increasingly serious, and in the aspect of military, the military equipment is continuously upgraded, particularly the radar detection technology is continuously developed, the requirement on the stealth performance of the military equipment is continuously improved, and the use condition is increasingly strict. Therefore, a new electromagnetic wave absorbing material is needed in both the civilian field and the military field to meet the requirements of wide frequency, low density, high performance and wide application range.

The absorption of electromagnetic waves by the wave-absorbing material should meet two basic requirements: impedance matching and attenuation characteristics, electromagnetic waves enter the interior of the material as much as possible, rather than being reflected by the surface, and electromagnetic waves entering the interior of the material can be efficiently absorbed. The thin-layer carbon prepared by the invention loads nano SiO₂The internal porous structure of the composite material increases the internal reflection path of the material, thereby improving the attenuation characteristic of the material, and the nano SiO₂As a wave-transmitting material, the impedance matching of the material is increased, so that the composite material has the advantages of wide frequency, low density, super-strong absorption and the like. Has wide application prospect in the wave-absorbing field.

Disclosure of Invention

The invention aims to provide an in-situ foaming process for preparing a thin-layer carbon-supported nano silica material in batches.

In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:

a kind of batcherPreparation of thin-layer carbon-loaded nano SiO₂The in-situ foaming process of the composite material specifically comprises the following steps:

(1) respectively dissolving a certain amount of glucose and ammonium nitrate in deionized water to form a solution I and a solution II;

the scheme (1) is characterized in that the glucose concentration in the solution I is 0.2g ∙ ml^-1The concentration of ammonium nitrate in the solution II is 0.2g ∙ ml^-1。

(2) Adding a certain mass of SiO into the solution I₂(200 nm), carrying out ultrasonic treatment on the mixed solution for 5 minutes to form a solution III;

the above aspect (2) is characterized in that SiO₂In a concentration of 0.06g ∙ ml^-1The solution was mixed and sonicated for 5 minutes.

(3) Heating and stirring the solution II, and simultaneously dropwise adding the solution III into the solution II to form a solution IV;

the above-mentioned means (3) is characterized in that the solution III is dropwise added while heating and stirring the solution II, and after all of the solution III is added, the heating and stirring are continued for 3 minutes.

(4) Putting the solution IV into a forced air drying oven, setting the temperature to be 120 ℃, and drying for 7 hours;

the above-mentioned means (4) is characterized in that the solution IV is dried for 7 hours in an air-blowing drying oven set at a temperature of 120 ℃.

(5) Putting the expansion body obtained in the step (4) into a tube furnace for heating, and obtaining thin-layer carbon-loaded nano SiO after heat treatment₂A composite material;

the above-mentioned means (5) is characterized in that it is ∙ min at 5 ℃ under an argon atmosphere^-1Heating to 700 ℃, preserving the heat for 2 hours at 700 ℃, and naturally cooling.

(6) Loading nano SiO on thin carbon layer₂Heating and mixing the composite material and paraffin in a certain proportion, and pressing a ring;

the above aspect (6) is characterized in that the thin carbon layer carries nano SiO₂The mass ratio of the composite material to the paraffin is 1: 5.

Compared with other wave-absorbing materials, the invention is characterized in that:

(1) nano SiO2₂The addition of the composite material increases the probability of electromagnetic waves entering the material, and keeps good wave absorbing capacity in a wider wave frequency range;

(2) the coating thickness is 3mm, the reflection loss peak value reaches-27.4 d B, and the frequency band of RL < -10d B reaches 7.1 GHz. When the thickness of the coating is 4mm, the reflection loss peak value reaches-47.7 d B, and the frequency band of RL < -10d B reaches 4.4 GHz;

(3) the raw materials are easy to obtain, the cost is low, the process is simple, and the method is suitable for batch production;

(4) the density is low, the material is light, and the large-scale application in the wave-absorbing field can be realized.

Drawings

FIG. 1 shows that the thin carbon-supported nano SiO prepared in example 1₂And (3) mixing the composite material and paraffin according to the mass ratio of 1:5 to prepare a ring, and then measuring the wave-absorbing performance curve.

FIG. 2 is a graph of the expanded precursor of example 1 after heating in a forced air oven, the expanded product occupying approximately half the volume of a 100ml beaker.

Figure 3 is an XRD pattern of the composite wave-absorbing material of example 1.

Detailed Description

The present invention is further illustrated by the following examples.

Example 1

Respectively dissolving 2g of glucose and 2g of ammonium nitrate in 10ml of deionized water, adding 0.6g of silicon dioxide (200 nm) into a glucose solution, then carrying out ultrasonic treatment on the mixed solution for 5 minutes to fully disperse the silicon dioxide into the glucose solution, heating and stirring the ammonium nitrate solution, simultaneously dropwise adding the silicon dioxide and glucose mixed solution which is just subjected to ultrasonic treatment into the ammonium nitrate solution, and stirring for 3 minutes after all the silicon dioxide and glucose mixed solution are added. Placing the stirred mixed solution into a forced air drying oven, drying at 120 deg.C for 7 hr to obtain cellular expansion body, transferring the prepared expansion body into a tube furnace, and ∙ min at 5 deg.C under argon atmosphere^-1The temperature is raised to 700 ℃ and the temperature is maintained at 700 ℃ for 2 hours. Thin layer carbon loading after heat treatmentNano SiO₂The composite material and paraffin are heated, mixed and pressed into rings according to the mass ratio of 1: 5.

FIG. 1 shows that the thin carbon-supported nano SiO prepared in this example₂The wave-absorbing performance curve of the composite material can be seen in the figure, when the thickness of the coating is 2.5 mm-5.5 mm, the wave-absorbing performance curve has parts<-10dB, wherein the reflection loss peak is highest at-47.7 dB for a coating thickness of 4mm, and the absorption frequency is widest at a coating thickness of 3mm, -10.5 GHz to 17.6GHz for a fraction below-10 dB, and 7.1GHz for a width. Fig. 2 is a diagram of an expanded precursor obtained by low-temperature foaming, and it can be seen that the expanded precursor has a porous honeycomb shape. FIG. 3 is a phase characterization XRD picture obtained after calcination, and analysis shows that the main phase is SiO₂。

The above description is only a preferred embodiment of the present invention, and it should be understood by those skilled in the art that the present invention is not limited by the examples, and several modifications and decorations can be made, and these modifications and decorations are also within the scope of the present invention.

Claims

1. Preparation of thin-layer carbon-loaded nano SiO₂The in-situ foaming process of the composite material is characterized by comprising the following steps of:

respectively dissolving a certain amount of glucose and ammonium nitrate in deionized water to form a solution I and a solution II;

adding SiO with a certain mass and a particle size of 200nm into the solution I₂Carrying out ultrasonic treatment on the mixed solution for 5 minutes to form a solution III;

heating and stirring the solution II, and simultaneously dropwise adding the solution III into the solution II to form a solution IV;

putting the solution IV into a forced air drying oven, setting the temperature to be 120 ℃, and drying for 7 hours;

heating the dried expansion body in a tubular furnace under the experimental condition of ∙ min at 5 ℃ in argon atmosphere^-1Heating to 700 ℃, preserving the heat for two hours at 700 ℃, and naturally cooling to obtain the thin-layer carbon-loaded nano SiO₂A composite material;

thin layer of carbonLoaded nano SiO₂The composite material and paraffin are heated and mixed uniformly according to a certain proportion, and then a ring is pressed.

2. The process as claimed in claim 1, wherein the glucose concentration in solution I is 0.2g ∙ ml^-1The concentration of ammonium nitrate in the solution II is 0.2g ∙ ml^-1。

3. Process according to claim 1, characterized in that the SiO in the final solution III₂In a concentration of 0.06g ∙ ml^-1The solution was mixed and sonicated for 5 minutes.

4. The process according to claim 1, wherein solution III is added dropwise while stirring solution II with heating, and after all addition, stirring with heating is continued for 3 minutes.

5. The process of claim 1, wherein the thin carbon layer supports nano-SiO₂The mass ratio of the composite material to the paraffin is 1: 5.