阅读说明：本技术 基于aao模板的碳基纳米材料的制备方法 (Preparation method of carbon-based nano material based on AAO template ) 是由 吴立志 张文豪 曹金乐 常仕民 郭伟 于 2019-11-08 设计创作，主要内容包括：本发明公开了一种基于AAO模板的碳基纳米材料的制备方法。所述方法首先利用采用二次阳极氧化法制备高度有序的多孔氧化铝模板,然后采用化学气相沉积技术在多孔氧化铝模板孔内沉积碳纳米材料,得到基于AAO模板的碳基纳米材料。本发明制得的材料在近红外波段的平均反射率为15.2％,有效提高了碳基纳米材料的激光利用率。(The invention discloses a preparation method of a carbon-based nano material based on an AAO template. The method comprises the steps of firstly preparing a highly ordered porous alumina template by adopting a secondary anodic oxidation method, and then depositing a carbon nano material in pores of the porous alumina template by adopting a chemical vapor deposition technology to obtain the carbon-based nano material based on the AAO template. The average reflectivity of the material prepared by the method in the near infrared band is 15.2%, and the laser utilization rate of the carbon-based nano material is effectively improved.)

1. The preparation method of the carbon-based nano material based on the AAO template is characterized by comprising the following specific steps:

step (1), carrying out slicing, cleaning, annealing and polishing pretreatment on an aluminum sheet with the purity of 99.999%;

step (2), carrying out primary anodic oxidation on the pretreated aluminum sheet;

step (3), soaking the aluminum sheet after the primary anodic oxidation in 5-6 wt% of H₃PO₄And 1.5 to 4 wt% CrO₃The mixed solution is soaked at the temperature of 60-70 ℃ for 30-40 min to dissolve the oxide layer;

step (4), carrying out secondary oxidation on the polished aluminum sheet with part of the oxide layer dissolved, and preparing a highly ordered AAO template;

step (5), soaking the secondarily oxidized aluminum sheet in 5-6 wt% of H₃PO₄Soaking in the solution at the temperature of 30-35 ℃ for 30-32 min, and reaming the AAO template prepared in the step (4) to obtain the AAO template with consistent aperture size;

and (6) depositing the carbon nano-material on the AAO template prepared in the step (5) by adopting a chemical vapor deposition technology: placing the AAO template prepared in the step (5) in a tube furnace under a vacuum condition, firstly heating to 450 ℃, and introducing Ar; then heating to 500-600 ℃, and introducing H₂Continuously heating to 600-650 ℃, introducing C₂H₂Wherein the Ar flow is 360-400 SCCM, H₂The flow rate is 55-60 SCCM, C₂H₂The flow rate is 110-120 SCCM, the valve of the vacuum pump is adjusted to maintain the air pressure in the pipe to be 45-50 kPa, and the reaction time is 60-70 min.

2. The method according to claim 1, wherein the anodizing electrolyte used in the steps (2) and (4) is selected from a phosphoric acid electrolyte, an oxalic acid electrolyte or a sulfuric acid electrolyte.

3. The preparation method according to claim 2, wherein in the steps (2) and (4), when the phosphoric acid electrolyte is adopted, the concentration of the electrolyte is 0.2-0.6 mol/L, the temperature is 0-2 ℃, the oxidation voltage is 45-80V, and the time is 10-20 min.

4. The preparation method according to claim 2, wherein in the steps (2) and (4), when the oxalic acid electrolyte is adopted, the concentration of the electrolyte is 0.2-0.6 mol/L, the temperature is 0-2 ℃, the oxidation voltage is 30-50V, and the time is 10-20 min.

5. The preparation method according to claim 2, wherein in the steps (2) and (4), a sulfuric acid electrolyte is adopted, the concentration of the electrolyte is 0.2-0.6 mol/L, the temperature is 0-2 ℃, the oxidation voltage is 10-25V, and the time is 10-20 min.

6. The production method according to claim 2, wherein in the step (6), the temperature rising rate is 10 ℃/min.

Technical Field

The invention belongs to the technical field of laser materials, and relates to a preparation method of a carbon-based nano material based on a porous alumina (AAO) template.

Background

Because the energy coupling efficiency of the laser and the material is low at present, in order to obtain the optimal energy utilization efficiency and control the volume of an engineering prototype, the highest energy output is required to be obtained with the lowest energy input, and the energy conversion efficiency of the laser-induced plasma is required to be very important. In the interaction process of the laser and the substance, one part of the laser irradiated on the surface of the material is absorbed by the material, and the other part of the laser is reflected and transmitted by the material, so that the material converts the absorbed laser energy into heat energy, the surface of the material is instantly melted, evaporated and ionized, and finally plasma micelles with high energy density are generated. Therefore, the interaction between the laser and the substance is actually the interaction between the laser and the plasma, so that the metal/nonmetal functional material with the surface with high light absorptivity has important potential application value in the field of laser application, and is an ideal material for improving the energy conversion efficiency of laser-induced plasma.

Document 1 (characteristics of laser-induced porous anodized aluminum plasma [ J)]The porous alumina template is prepared by adopting a Chinese laser 2019,46(02): 271-277) through an electrochemical method, and the average reflectivity of the porous alumina template in a near infrared band is about 60 percent. Document 2(Precisely Controlled Reactive MultilayerFilms with Excellent Energy requirement for Laser-Induced Ignition [ J)]Nanoscale reacher Letter (2019)14: 301) preparation of TiO by magnetron sputtering₂/Al，MnO₂The average reflectivity of three flyers of/Al, CuO and Al is respectively about 72%, 62% and 65% in the near infrared band. Therefore, the average reflectivity of the existing material in the near infrared band is still higher, and the laser utilization rate is still to be improved.

Disclosure of Invention

The invention aims to provide a preparation method of an AAO template-based carbon-based nano material with high laser utilization rate.

The technical solution for realizing the purpose of the invention is as follows:

the preparation method of the carbon-based nano material based on the AAO template comprises the following steps of firstly preparing a highly ordered porous alumina template by using a secondary anodic oxidation method, then depositing a carbon nano material in pores of the porous alumina template by using a Chemical Vapor Deposition (CVD) technology, and finally obtaining the carbon-based nano material based on the AAO template, wherein the preparation method comprises the following specific steps:

step (1), slicing, cleaning, annealing and polishing pretreatment are carried out on an aluminum sheet with the purity of 99.999 percent (5N);

step (2), carrying out primary anodic oxidation on the pretreated aluminum sheet;

step (3), soaking the aluminum sheet after the primary anodic oxidation in 5-6 wt% of H₃PO₄And 1.5 to 4 wt% CrO₃The mixed solution is soaked at the temperature of 60-70 ℃ for 30-40 min to dissolve the oxide layer, and the porous distribution obtained by secondary oxidation is more uniform by dissolving part of the oxide layer;

step (4), carrying out secondary oxidation on the polished aluminum sheet with part of the oxide layer dissolved, and preparing a highly ordered AAO template;

step (5), soaking the secondarily oxidized aluminum sheet in 5-6 wt% of H₃PO₄Soaking in the solution at the temperature of 30-35 ℃ for 30-32 min, and reaming the AAO template prepared in the step (4) to obtain the AAO template with consistent pore size, so as to better deposit the carbon nano material;

and (6) depositing the carbon nano-material on the AAO template prepared in the step (5) by adopting a Chemical Vapor Deposition (CVD) technology: placing the AAO template prepared in the step (5) in a tube furnace under a vacuum condition, firstly heating to 450 ℃, and introducing Ar; then heating to 500-600 ℃, and introducing H₂Continuously heating to 600-650 ℃, introducing C₂H₂Wherein the Ar flow is 360-400 SCCM, H₂The flow rate is 55-60 SCCM, C₂H₂The flow rate is 110-120 SCCM, the valve of the vacuum pump is adjusted to maintain the air pressure in the pipe to be 45-50 kPa, and the reaction time is 60-70 min.

In the steps (2) and (4), the anodic oxidation electrolyte is an electrolyte conventionally used in the field, and can be selected from phosphoric acid electrolyte, oxalic acid electrolyte or sulfuric acid electrolyte. When the phosphoric acid electrolyte is adopted, the concentration of the electrolyte is 0.2-0.6 mol/L, the temperature is 0-2 ℃, the oxidation voltage is 45-80V, and the time is 10-20 min. When the oxalic acid electrolyte is adopted, the concentration of the electrolyte is 0.2-0.6 mol/L, the temperature is 0-2 ℃, the oxidation voltage is 30-50V, and the time is 10-20 min. A sulfuric acid electrolyte is adopted, the concentration of the electrolyte is 0.2-0.6 mol/L, the temperature is 0-2 ℃, the oxidation voltage is 10-25V, and the time is 10-20 min.

Preferably, in the step (6), the temperature increase rate is 10 ℃/min.

Compared with the prior art, the invention has the remarkable advantages that:

(1) preparing an AAO template by adopting a secondary anodic oxidation method to obtain an aluminum sheet with high length-diameter ratio, uniform pore size and good arrangement directionality;

(2) the chemical vapor deposition technology is adopted, the reaction is controllable, the device is simple, a catalyst is not needed, and the carbon nano material with uniform size, consistent orientation and high purity can be prepared.

(3) The carbon-based nano material based on the AAO template has the average light reflectivity of 15.2% in the near-infrared band (900 nm-1700 nm), greatly improves the laser absorption rate, and is an ideal material for improving the energy conversion efficiency of laser-induced plasma.

Drawings

FIG. 1 is a schematic flow chart of the preparation method of the present invention.

Fig. 2 is a cross-sectional SEM image of the AAO template-based carbon-based nanomaterial prepared in example 1.

Fig. 3 is a cross-sectional SEM image of the AAO template-based carbon-based nanomaterial prepared in comparative example 1.

FIG. 4 is a graph of the results of near infrared band reflectivity tests of the prepared AAO template-based carbon-based nanomaterial.

Detailed Description

The present invention will be described in more detail with reference to the following examples and the accompanying drawings.

With reference to fig. 1, the preparation method of the present invention has the following process flow:

1. an aluminum sheet with the purity of 99.999 percent (5N) is selected and pretreated, and the thickness is 0.50 mm. The process mainly comprises the steps of cleaning, annealing and polishing the aluminum sheet.

2. Carrying out primary oxidation (voltage-stabilizing oxidation) on the polished aluminum sheet, and adopting phosphoric acid electrolyte with the concentration of 0.2-0.6 mol/L, wherein the temperature is 0-2 ℃, the oxidation voltage is 45-80V, and the time is 10-20 min; or 0.2-0.6 mol/L oxalic acid electrolyte is adopted, the temperature is 0-2 ℃, the oxidation voltage is 30-50V, and the time is 10-20 min; or 0.2-0.6 mol/L sulfuric acid electrolyte is adopted, the temperature is 0-2 ℃, the oxidation voltage is 10-25V, and the time is 10-20 min.

3. Placing the primarily oxidized polished aluminum sheet in 5-6 wt% of H₃PO₄And 1.5 to 4 wt% CrO₄At 70 ℃ for 30min, dissolving part of Al₂O₃A thin layer.

4. Then, the secondary anodic oxidation is carried out, and the oxidation conditions are the same as the primary oxidation conditions.

5. Placing the secondarily oxidized polished aluminum sheet in 5-6 wt% of H₃PO₄And (4) reaming the hole in the solution at the temperature of 30-35 ℃ for 30-32 min.

6. The carbon nanomaterial is deposited on the porous alumina template by a CVD method. Firstly, placing the porous alumina template in the step into a porcelain boat and pushing the porcelain boat to the middle part of a corundum tube, wherein the tube opening of the corundum tube is sealed by a stainless steel flange. The tube was evacuated by a vacuum pump and the furnace temperature was then raised to 700 ℃ at a ramp rate of 10 ℃/min. When the temperature of the furnace rises to 450 ℃, introducing Ar; when the temperature is raised to 500-600 ℃, H is introduced₂When the temperature is raised to 600-650 ℃, C is introduced₂H₂. The flow of Ar is adjusted to be 360-400 SCCM, H by adjusting the flow meter₂The flow rate is 55-60 SCCM, C₂H₂The flow rate is 110-120 SCCM, the valve of the vacuum pump is adjusted to maintain the air pressure in the pipe to be 45-50 kPa, and the reaction time is 60-70 min.

Example 1

The preparation method of the carbon-based nano material based on the AAO template comprises the following steps:

1. an aluminum sheet with the purity of 99.999 percent (5N) is selected and pretreated, and the thickness is 0.50 mm. The process mainly comprises the steps of cleaning, annealing and electrochemical polishing treatment of an aluminum sheet;

2. carrying out primary anodic oxidation on the polished aluminum sheet, and adopting oxalic acid with the concentration of 0.3mol/L as electrolyte, wherein the temperature is 0-2 ℃, the oxidation voltage is 45V, and the time is 15 min;

3. the primary oxidized aluminum sheet was placed in 6 wt% H₃PO₄And 1.8 wt%CrO₄At 70 ℃ for 30min, part of Al is dissolved₂O₃A thin layer;

4. then carrying out secondary anodic oxidation under the same oxidation condition as the primary oxidation condition;

5. placing the secondarily oxidized polished aluminum sheet in 6 wt% H₃PO₄In the solution, keeping the temperature at 30 ℃ for 32min, and reaming to obtain AAO templates with consistent pore size and uniform distribution;

6. and (3) placing the porous alumina template in the step into a porcelain boat and pushing the porcelain boat to the middle part of the corundum tube, wherein the tube opening of the corundum tube is sealed by a stainless steel flange. The tube was evacuated by a vacuum pump and the furnace temperature was then raised to 700 ℃ at a ramp rate of 10 ℃/min. When the temperature of the furnace rises to 450 ℃, introducing Ar; when the temperature is raised to 500-600 ℃, H is introduced₂When the temperature is raised to 600-650 ℃, C is introduced₂H₂. The flow of Ar is adjusted to 400SCCM, H by adjusting the flow meter₂Flow 60SCCM, C₂H₂The flow rate is 120SCCM, the air pressure in the pipe is maintained at 50kPa by adjusting the valve of the vacuum pump, and the reaction time is 60 min. The cross-sectional view of the product obtained is shown in FIG. 2.

Comparative example 1

The comparative example is basically the same as example 1, and in a step 6 which is only different, when the furnace temperature is raised to 500 ℃, Ar is introduced; when the temperature is raised to 550-650 ℃, H is introduced₂When the temperature is raised to 650-700 ℃, C is introduced₂H₂. The cross-sectional view of the resulting product is shown in FIG. 3.

It can be seen from fig. 2 that the carbon nanomaterial prepared in example 1 is deposited along the AAO template, and the carbon nanomaterial is uniform in size and uniform in orientation. As can be seen from fig. 3, the carbon nanomaterial deposited in comparative example 1 was damaged, incomplete, and non-uniformly oriented. As can be seen from fig. 4, after the test of the near-infrared spectrometer test system, the average reflectivity of the sample of example 1 in the near-infrared band (900nm to 1700nm) is 15.2%, while the average reflectivity of the sample of comparative example 1 in the near-infrared band (900nm to 1700nm) is 24.6%, compared with that of the sample of example 1, the laser utilization rate can be improved more effectively.