CN114672794A - Metallized aramid fiber honeycomb material, and preparation method and application thereof - Google Patents

Abstract

The invention provides a metallized aramid fiber honeycomb material, and a preparation method and application thereof. The preparation method comprises the step S1 of cleaning the aramid fiber honeycomb to obtain a clean aramid fiber honeycomb; step S2, carrying out activation treatment on the clean aramid fiber honeycomb to obtain an active aramid fiber honeycomb; and step S3, placing the active aramid fiber honeycomb into a chemical iron and nickel plating solution for chemical plating to form an iron and nickel plating layer on the inner surface of the active aramid fiber honeycomb. The cleaning can remove solid small particle impurities such as dust and the like attached to the surface of the aramid fiber honeycomb and stains such as mineral oil or grease and the like adhered to the pore wall; the activation treatment can enable the iron-nickel plating layer to be deposited on the surface of the aramid fiber honeycomb more easily; and finally, carrying out chemical plating to form a uniform iron-nickel plating layer on the surface of the active aramid fiber honeycomb, thereby realizing the metallization of the aramid fiber paper honeycomb. The preparation method of the metallized aramid fiber honeycomb material is simple, and the obtained metallized aramid fiber paper honeycomb material is good in corrosion resistance, good in air permeability, high in plane compression strength and excellent in shielding performance.

Description

Metallized aramid honeycomb material, its preparation method and application

technical field

The present invention relates to the technical field of electromagnetic shielding, in particular, to a metallized aramid honeycomb material, a preparation method and application thereof.

Background technique

With the continuous development and improvement of research technology, various types of shielding materials have been developed and applied one after another. At present, the electromagnetic shielding materials mainly used can be divided into air-tight and air-permeable according to the air permeability. For equipment such as chassis with vents, which need to be ventilated and shielded from electromagnetic waves at the same time, a breathable electromagnetic shielding material needs to be used. The air permeable electromagnetic shielding materials commonly used at this stage are mainly metal meshes and waveguide windows; and the metal foam with excellent shielding performance, light weight and air permeability is a new type of electromagnetic shielding material developed in recent years. It not only has good electrical conductivity or magnetic properties of metal materials, but also has multiple reflection losses of electromagnetic waves in its pores due to the porous structure inside, so that it has higher electromagnetic wave shielding ability than two-dimensional metal meshes. Even the shielding effect of the waveguide window can be achieved.

Electromagnetic shielding refers to blocking the electromagnetic wave propagation path between the electromagnetic pollution source and the designated area, so as to reduce or eliminate the adverse effect of the pollution source on the sensitive equipment, devices or human body in the designated area. According to the different working principles of shielding, it can be divided into three categories: electrostatic shielding, magnetic shielding and electromagnetic shielding. Among them, electrostatic shielding and magnetic shielding are only two special types of electromagnetic shielding.

The shielding ability and effect of various shielding materials to external electromagnetic waves are usually expressed in shielding effectiveness (SE), and the unit of SE is expressed in decibels (dB). The Schelkunoff formula is used to calculate the shielding effectiveness of electromagnetic materials:

SE = SE _R +SE _A +SE _M .

where SE _R is the reflection loss, SE _A is the absorption loss, and _SEM is the multiple reflection loss. The reflection loss is caused by the impedance mismatch between the shielding material and the space medium, and is the result of the interaction of charged particles in the material with the electromagnetic field; the absorption loss is caused by the interaction of magnetic dipoles or electric dipoles with the electromagnetic field. The multiple reflection loss is caused by the inhomogeneity inside the shield.

Aramid paper honeycomb core material, as a special composite material structure, has the characteristics of high specific strength, good shock absorption, and good heat insulation. scattering, and the paper honeycomb is cheap and economical. In view of the above advantages of honeycomb core material, honeycomb core material is not only widely used in civil, construction and other fields, but also occupies an important position in aviation and aerospace fields.

In addition, due to the advantages of high specific stiffness and low relative density, honeycomb sandwich structure has strong design and simple processing and molding, and has been widely used in aerospace and rail transportation fields. Considering the large-area use of the honeycomb sandwich structure in the main structure of the aircraft cabin, the reasonable development of the honeycomb core material with electromagnetic shielding function can effectively protect the precision instruments and passengers in the aviation cabin from electromagnetic interference, and realize the aviation core. The integrated design of the structure and function of the core material improves the space utilization rate of the honeycomb core material as a whole, so as to realize the intelligent lightweight design of the core material and the integrated application purpose of the function integration. With the rapid development of electronic science and cutting-edge technology, the application of honeycomb sandwich composite materials with shielding properties in modern electronic countermeasure technology is not limited to the field of national defense aircraft and ship equipment, but also extended to communication base stations, vehicle-mounted and indoor radomes. and other civil technology.

Hexagonal honeycomb structures, imitating natural honeycombs, are widely used as core materials for sandwich structures due to their light weight and high strength and stiffness. When the radar wave enters the interior of the sandwich structure from the wave-transmitting layer, the sandwich cavity performs multiple scattering and absorption, maximally attenuating the radar wave energy and thus obtaining a broadband and high-strength shielding and absorbing effect.

Electromagnetic shielding is a measure used to attenuate electromagnetic fields caused by certain emission sources in a certain area of space. In most cases, the shield can be made of metals such as copper, aluminum, steel, but for constant and lower frequency magnetic fields, materials such as ferrite can also be used as shields. When the electromagnetic wave reaches the surface of the shield, the reflection of the incident wave occurs due to the discontinuity of impedance at the interface between the air and the metal. This kind of reflection does not require the shielding material to have a certain thickness, but only requires discontinuity on the interface; the energy that is not reflected from the surface and enters the shielding body is attenuated by the shielding material during the forward propagation in the body, and also It's called absorption. When the residual energy that has not been attenuated in the shielding body is transmitted to the other surface of the material, it encounters the discontinuous interface of metal-air impedance, which will form a re-reflection and return to the shielding body again. This reflection may have multiple reflections at the interface of the two metals. In a word, the attenuation of electromagnetic shielding body is mainly based on the reflection and absorption of electromagnetic waves.

The Chinese patent application with the application number of 201710266357.8 discloses an electromagnetic shielding honeycomb core material, a preparation method thereof and an implantation tooling. In the cavity of each honeycomb unit of the present invention, there are 1 to 5 layers of parallel electromagnetic shielding diaphragms; The steps of the electromagnetic shielding diaphragm are as follows: selecting a honeycomb matrix; manufacturing the electromagnetic shielding diaphragm blank; implanting the electromagnetic shielding diaphragm blank. The implant tool of the invention is composed of the upper handle and the lower implant rod connected. Due to the limitation of its tooling, the invention cannot realize industrial production and batch application.

The Chinese patent application with the application publication number CN108724822A discloses a preparation method of an electromagnetic shielding honeycomb core material. The graphene/ferrite hybrid material is prepared by preparing the graphene/ferrite hybrid material by magnetic deposition. The particles are uniformly attached to the fabric carrier to form the graphene/ferrite hybrid particle electromagnetic shielding fabric. The electromagnetic shielding interlayer is prepared by using prepreg, adhesive film and electromagnetic shielding fabric. Finally, the electromagnetic shielding interlayer and the honeycomb core material are composited into a sandwich electromagnetic shielding honeycomb structure by means of gluing. This technology realizes the comprehensive utilization of low-cost design, manufacture and technology integration of electromagnetic shielding honeycomb core material, but the operation is complicated, single-layer graphene/ferrite electromagnetic shielding honeycomb core material or multi-layer graphene/ferrite electromagnetic shielding honeycomb The core material cannot meet the modern needs of ventilation and electromagnetic wave shielding at the same time.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a metallized aramid honeycomb material, its preparation method and application, to solve the problem of complicated preparation method of electromagnetic shielding honeycomb core material in the prior art.

In order to achieve the above object, according to an aspect of the present invention, a preparation method of a metallized aramid honeycomb material is provided, the preparation method comprising: step S1, cleaning the aramid honeycomb to obtain a clean aramid honeycomb; step S2, Activating the clean aramid honeycomb to obtain an active aramid honeycomb; step S3, placing the active aramid honeycomb in an electroless iron-nickel plating solution for electroless plating to form an iron-nickel coating on the inner surface of the active aramid honeycomb.

Further, the above-mentioned step S1 includes performing alkali washing and water washing on the aramid honeycomb in sequence to obtain a clean aramid honeycomb.

Further, the alkaline solution used in the above-mentioned alkaline washing includes NaOH with a concentration of 10 to 30 g/L and an OP emulsifier of 1 to 3 g/L. Ultrasound is preferably performed during the alkaline process, and the ultrasonic power is preferably 50 to 200W, and the ultrasonic time is 50 to 200 W. It is 5～30min, preferably alkali washing is carried out at 30～70 ℃.

Further, the above step S2 includes: sequentially infiltrating and heat-treating the clean aramid honeycomb in an activation solution to obtain an activated aramid honeycomb, and the activation solution includes nickel acetate in a ratio of 1g:0.5-1.5g:20-40mL, the first A reducing agent and water, preferably the first reducing agent is selected from any one or more of sodium hypophosphite, glucose, formaldehyde, acetaldehyde and sodium hypophosphite.

Further, the above-mentioned soaking treatment time is 5～10min, preferably the temperature of heat treatment is 195～205°C, and the time of heat treatment is 30～60min.

Further, before the above-mentioned soaking treatment, step S2 also includes a process of performing surface corrosion on the clean aramid honeycomb. Preferably, the surface corrosion process includes: using an etchant to etch the clean aramid fiber, and the etchant includes a volume ratio of Hydrogen peroxide and sulfuric acid in a ratio of 1:2 to 4, preferably the corrosion treatment time is 3 to 10 minutes, and the mass concentration of the sulfuric acid is preferably 90 to 99%.

Further, in the above-mentioned step S3, the electroless iron-nickel plating solution includes a soluble nickel salt, a soluble ferrous salt and a second reducing agent, wherein the soluble nickel salt is selected from any one of nickel sulfate, nickel acetate and nickel hypophosphite. or more, the soluble ferrous salt is selected from any one or more of ammonium ferrous sulfate hexahydrate, ferrous chloride tetrahydrate, and the second reducing agent is selected from hypophosphite, sodium borohydride, borane, Any one or more of hydrazine; preferably, the concentration of the soluble nickel salt is 0.04-0.09mol/L, the concentration of the soluble ferrous salt is 0.01-0.06mol/L, and the concentration of the second reducing agent is 0.005-0.01 mol/L; preferably, the pH value of the electroless iron-nickel plating solution is 8.0 to 11.5, preferably, the temperature of the electroless plating is 90° C. and the time is 30 to 60 minutes, preferably the electroless iron-nickel plating solution also includes a catalyst, and the catalyst is selected from the group consisting of propane two. Any one or more of acid, succinic acid, aminoacetic acid, propionic acid, and sodium fluoride, and the concentration of the catalyst is 0.001-0.005 mol/L.

According to another aspect of the present invention, a metallized aramid honeycomb material is provided, which is prepared by any of the above-mentioned preparation methods.

According to yet another aspect of the present invention, a metallized aramid honeycomb material is provided, the metallized aramid honeycomb material includes an aramid honeycomb matrix and an iron-nickel coating, and the iron-nickel coating is provided on the inner surface and the outer surface of the aramid honeycomb matrix On the surface, preferably the mass ratio of the aramid honeycomb matrix and the iron-nickel coating is 100-10:1, the thickness of the iron-nickel coating is preferably 10-30 μm, the iron-nickel coating preferably contains phosphorus, and the mass ratio of iron, nickel and phosphorus is preferred It is 0.4～0.9:0.1～0.6:0.05～0.1.

According to another aspect of the present invention, an electromagnetic shielding structure is provided, comprising an electromagnetic shielding honeycomb core material, and the electromagnetic shielding honeycomb core material is any of the above-mentioned metallized aramid honeycomb materials.

Applying the technical solution of the present invention, firstly, cleaning is performed to remove solid small particles of impurities such as dust attached to the surface of the aramid honeycomb and stains such as mineral oil or grease adhered to the pore walls, and then activation treatment is performed to make the surface of the aramid honeycomb easier. Deposit an iron-nickel coating. Finally, chemical plating is performed to form a uniform iron-nickel coating on the surface of the active aramid honeycomb, which realizes the metallization of the aramid paper honeycomb. As can be seen from the above description, the preparation method of the metallized aramid honeycomb material of the present application is simple, and the metallization of the aramid paper honeycomb can be completed by cleaning, activation and chemical plating, and the obtained corrosion resistance, good air permeability, Metallized aramid paper honeycomb material with high plane compressive strength and excellent shielding properties.

Detailed ways

It should be noted that the embodiments in the present application and the features of the embodiments may be combined with each other in the case of no conflict. The present invention will be described in detail below with reference to the embodiments.

As described in the background of this application, the electromagnetic shielding honeycomb core material can satisfy both the functions of air permeability and electromagnetic wave shielding. However, due to the structural design, some electromagnetic shielding honeycomb core materials in the prior art cannot meet the requirements of air permeability. Moreover, the preparation methods of the electromagnetic shielding honeycomb core materials in the prior art are all too complicated. In order to solve the above problems, the present application provides a metallized aramid honeycomb material, its preparation method and application.

In a typical embodiment of the present application, a method for preparing a metallized aramid honeycomb material is provided. The preparation method includes: step S1, cleaning the aramid honeycomb to obtain a clean aramid honeycomb; step S2, Activating the clean aramid honeycomb to obtain an active aramid honeycomb; step S3, placing the active aramid honeycomb in an electroless iron-nickel plating solution for electroless plating to form an iron-nickel coating on the inner surface of the active aramid honeycomb.

For the preparation method of the metallized aramid honeycomb material of the present application, firstly, cleaning is performed to remove solid small particles of impurities such as dust attached to the surface of the aramid fiber honeycomb and stains such as mineral oil or grease adhering to the pore wall, and secondly, an activation treatment is performed, It makes it easier to deposit Fe-Ni coating on the aramid honeycomb surface. Finally, chemical plating is carried out to form a uniform iron-nickel coating on the surface of the active aramid honeycomb, which realizes the metallization of the aramid paper honeycomb. As can be seen from the above description, the preparation method of the metallized aramid honeycomb material of the present application is simple, and the metallization of the aramid paper honeycomb can be completed by cleaning, activation and chemical plating, and the obtained corrosion resistance, good air permeability, Metallized aramid paper honeycomb material with high plane compressive strength and excellent shielding properties.

In the above-mentioned cleaning steps, methods commonly used in the prior art for removing small particles and grease can be selected. In order to play a better cleaning effect on the stains such as mineral oil or grease adhered on the aramid honeycomb hole wall, it is preferable that the above-mentioned step S1 comprises performing alkali washing and water washing on the aramid honeycomb in turn to obtain a clean aramid honeycomb. Wash with water after alkaline washing to remove residual lye.

The above-mentioned alkaline washing can use the alkaline solution commonly used for alkaline washing in the prior art. In order to obtain a better cleaning effect for the aramid fiber honeycomb, preferably the alkaline solution used in the above-mentioned alkaline washing includes NaOH with a concentration of 10-30 g/L and 1- 3g/L OP emulsifier is preferably ultrasonicated in an alkaline process, more preferably ultrasonic power is 50-200W, ultrasonic time is 5-30min, and alkaline washing is preferably performed at 30-70°C. The use of 10-30g/L sodium hydroxide solution and 1-3g/L OP emulsifier can enhance the removal of mineral oil or grease, and the emulsifier can also significantly reduce the surface tension of grease and make it more dispersed In the water. Further, performing the preferred ultrasonic treatment can further enhance the effect of removing dust and other small solid particles and impurities from diffusing into the water.

The activation treatment method of aramid honeycomb can be referred to the commonly used activation method of fibers in the prior art, such as the activation method catalyzed by precious metals such as silver salt or palladium salt. In order to save costs and simplify the operation steps, the application is implemented in a method. In an example, the above step S2 includes: sequentially infiltrating and heat-treating the clean aramid honeycomb in an activation solution to obtain an activated aramid honeycomb, and the above activation solution comprises nickel acetate, The first reducing agent and water. Through the treatment of the above activation solution, the nickel salt in the activator can be decomposed into elemental nickel to form the catalytic active center of electroless nickel plating on the surface of the aramid honeycomb, so that the subsequent electroless nickel plating can be firmly combined with the aramid honeycomb and smooth and uniform. Nickel-phosphorus coating.

The first reducing agent in the activation solution of the present application can be selected from any of the water-soluble reducing agents in the prior art. Any one or more of sodium hypophosphite, glucose, formaldehyde, acetaldehyde and sodium hypophosphite. The above-mentioned reducing agent is easily adsorbed on the surface of the substrate and can maintain a stable small molecular compound in an aqueous solution at room temperature, and can react with the aramid honeycomb relatively uniformly, so that the coating formed by the subsequent chemical plating is dense and uniform, so the corrosion resistance is good.

In order to improve the activation effect and activation efficiency at the same time, the soaking treatment time is 5-10min, preferably the heat-treatment temperature is 195-205℃, and the heat-treatment time is 30-60min. When the treatment time is less than the above-mentioned preferred time range, the activation effect is not ideal; when the treatment time is longer than the preferred time, the improvement of the treatment effect is not obvious.

Subsequent chemical plating is mainly chemical plating metal layer on the inner surface or outer surface of the aramid honeycomb. In order to improve the adhesion of the plated metal, in an embodiment, before the infiltration treatment is performed, the above step S2 further Including the process of surface corrosion of clean aramid honeycomb, also known as surface roughening, preferably the process of surface corrosion includes: using corrosive liquid to etch clean aramid fiber, and the corrosive liquid includes a volume ratio of 1:2 to 4. Hydrogen peroxide and sulfuric acid, preferably the corrosion treatment time is 3-10 min, and the mass concentration of sulfuric acid is preferably 90-99%. The surface of the aramid fiber is roughened by the surface corrosion treatment, which is conducive to the formation of multiple surface active points, so that the coating can be formed faster in the subsequent electroless plating, and the adhesion of the coating is stronger. Within the above-mentioned preferred parameters, the occurrence of excessive or insufficient corrosion should be minimized.

The method of forming the iron-nickel metal layer by electroless plating can be based on the chemical plating method of the metal layer in the prior art. In an embodiment, in the above step S3, the electroless iron-nickel plating solution includes soluble nickel salt and soluble ferrous salt. and the second reducing agent, wherein the soluble nickel salt is selected from any one or more of nickel sulfate, nickel acetate and nickel hypophosphite, and the soluble ferrous salt is selected from ammonium ferrous sulfate hexahydrate and ferrous chloride tetrahydrate Any one or more of the second reducing agent is selected from any one or more of hypophosphite, sodium borohydride, borane and hydrazine. By using the above reagents, a dense and uniform iron-nickel coating can be formed on the surface of the aramid honeycomb, thereby preparing a metallized aramid paper honeycomb material with good corrosion resistance, high plane compressive strength and excellent shielding performance. Further, when selecting nickel hypophosphite as the source of nickel and hypophosphite, the co-deposition of phosphorus and nickel can occur in the electroless plating process, so the electroless iron-nickel coating is an iron-nickel-phosphorus alloy coating in which phosphorus is dispersed. , By controlling the phosphorus content between 1% and 15%, the obtained alloy coating is dense and non-porous, and the corrosion resistance is much better than that of electroplating nickel. In addition, the use of nickel hypophosphite avoids the introduction of sulfate ions, and the cumulative amount of alkali metal ions can be minimized, thereby avoiding the reaction of sulfate and metal ions to generate stable salts, resulting in impurities in the coating, which in turn affects the coating. performance.

Those skilled in the art can adjust the thickness of the formed metal layer and the nickel-iron composition according to the soluble nickel salt concentration and the soluble ferrous salt concentration used. In order to achieve more ideal corrosion resistance and electromagnetic shielding performance, soluble The concentration of nickel salt is 0.04-0.09mol/L, the concentration of soluble ferrous salt is 0.01-0.06mol/L, and the concentration of the second reducing agent is 0.005-0.01mol/L; the pH value of the electroless iron-nickel plating solution is preferably 8.0-11.5, preferably, the temperature of the electroless plating is 90° C. and the time is 30-60 minutes. By optimizing the reagent concentration, reaction conditions, etc., parameters such as the thickness and composition of the coating can be well controlled, so that the prepared metallized aramid honeycomb material has better mechanical properties and application properties.

In an embodiment, it is preferred that the electroless iron-nickel plating solution also includes a catalyst, and the catalyst is selected from any one or more of malonic acid, succinic acid, glycine, propionic acid, and sodium fluoride. The concentration of the above-mentioned catalyst It is 0.001～0.005mol/L. The selection of the above catalyst can speed up the reaction speed of electroless plating. And the concentration of the catalyst is controlled so as to achieve a better catalytic effect without wasting the reagent.

In another typical embodiment of the present application, a metallized aramid honeycomb material is provided, and the metallized aramid honeycomb material is prepared by any of the above-mentioned preparation methods.

Using the metallized aramid honeycomb material obtained by the preparation method of the present application, a dense and uniform metal coating can be formed on the surface of the aramid honeycomb in a controllable manner, and a material with good corrosion resistance, good air permeability, high plane compressive strength and excellent shielding performance can be obtained. Metallized aramid paper honeycomb material.

In yet another typical embodiment of the present application, a metallized aramid honeycomb material is provided, the metallized aramid honeycomb material includes an aramid honeycomb matrix and an iron-nickel coating, and the iron-nickel coating is provided on the aramid honeycomb matrix Preferably, the mass ratio of the aramid honeycomb matrix and the iron-nickel coating is 100-10:1, the thickness of the iron-nickel coating is preferably 10-30 μm, and the iron-nickel coating preferably contains phosphorus, preferably iron and nickel. The mass ratio with phosphorus is 0.4-0.9:0.1-0.6:0.05-0.1. Metallized aramid honeycomb material with the above structure. The shielding effect of the eddy current is used, that is, when the high-frequency electromagnetic wave is incident, the Joule heat generated by the eddy current consumes the energy of the incident electromagnetic field by using the metal material to have a certain resistance, thereby achieving the shielding effect. In addition, it also has the characteristics of good corrosion resistance, good air permeability, high plane compressive strength and excellent shielding performance.

In yet another typical embodiment of the present application, an electromagnetic shielding structure is provided, comprising an electromagnetic shielding honeycomb core material, and the electromagnetic shielding honeycomb core material is any of the above-mentioned metallized aramid honeycomb materials. The above-mentioned electromagnetic shielding structure using the metallized aramid honeycomb material of the present application as the electromagnetic shielding honeycomb core material has the characteristics of strong structural stability, good air permeability and excellent shielding effect.

The beneficial effects of the present application will be further described below with reference to the embodiments.

Example 1:

(1) Cleaning

Put the aramid paper honeycomb (300mm*300mm*5mm) in the alkaline solution, treat it at 50℃ and the ultrasonic power is 120W for 10min, remove the impurities on the surface of the inner hole wall of the honeycomb, and then rinse the surface of the material with water to remove the impurities. Residual alkaline solution, the alkaline solution contains: 20g/L NaOH and 2g/L OP emulsifier.

(2) Micro-etching

Micro-etching is prepared by using hydrogen peroxide and sulfuric acid with a mass fraction of 98.3% and a volume ratio of 1:4. Put the washed aramid paper honeycomb in the micro-etching solution for about 5 minutes, take it out, wash it with water, rinse the surface with deionized water, rinse the surface with deionized water, and dry it (105℃, 1.5h).

(3) Activation

The micro-etched aramid paper honeycomb was soaked for about 10 minutes with an activation solution with a concentration of nickel acetate (g): sodium hypophosphite (g): water (ml) = 1:1:30, and then heat-treated at 200 °C for 60 minutes , and then rinsed with deionized water to remove the residual activation solution.

(4) Electroless iron nickel plating

The activated aramid paper honeycomb was electroless plated with iron and nickel in an alkaline solution at 90°C, wherein the composition and process conditions of the electroless iron and nickel plating solution: nickel hypophosphite 0.06mol/L, ferrous ammonium sulfate hexahydrate 0.04mol/L, sodium borohydride 0.005mol/L, sodium fluoride 0.005mol/L, pH value 9.0, temperature value 90°C, treatment time 60min.

Example 2:

(1) Cleaning

Put the aramid paper honeycomb (300mm*300mm*15mm) in the alkaline solution, treat it at 50℃ and the ultrasonic power is 150W for 10min to remove the impurities on the surface of the inner hole wall of the honeycomb, and then rinse the surface of the material with water to remove the impurities. Residual alkaline solution, the alkaline solution contains: 30g/L NaOH and 2g/L OP emulsifier.

(2) Micro-etching

Micro-etching is prepared by using hydrogen peroxide and sulfuric acid with a mass fraction of 98.3% and a volume ratio of 1:4. Put the washed aramid paper honeycomb in the micro-etching solution for about 5 minutes, take it out, wash it with water, rinse the surface with deionized water, rinse the surface with deionized water, and dry it (105℃, 1.5h).

(3) Activation

The micro-etched aramid paper honeycomb was soaked for about 10 minutes with an activation solution with a concentration of nickel acetate (g): sodium hypophosphite (g): water (ml) = 1:1:30, and then heat-treated at 200 °C for 50 minutes , and then rinsed with deionized water to remove the residual activation solution.

(4) Electroless iron nickel plating

The activated aramid paper honeycomb was electroless plated with iron and nickel in an alkaline solution at 90°C, wherein the composition and process conditions of the electroless iron-nickel plating solution: nickel hypophosphite 0.05mol/L, ferrous ammonium sulfate hexahydrate 0.05mol/L, sodium borohydride 0.008mol/L, pH value 9.5, temperature value 90℃, treatment time 60min.

Example 3:

(1) Cleaning

Put the aramid paper honeycomb (300mm*300mm*20mm) in the alkaline solution, treat it at 50℃ and the ultrasonic power is 160W for 10min, remove the impurities on the surface of the inner hole wall of the honeycomb, and then rinse the surface of the material with water to remove the impurities. Residual alkaline solution, the alkaline solution contains: 10g/L NaOH and 1g/L OP emulsifier.

(2) Micro-etching

Micro-etching is prepared by using hydrogen peroxide and sulfuric acid with a mass fraction of 98.3% and a volume ratio of 1:4. Put the washed aramid paper honeycomb in the micro-etching solution for about 5 minutes, take it out, wash it with water, rinse the surface with deionized water, rinse the surface with deionized water, and dry it (105℃, 1.5h).

(3) Activation

The micro-etched aramid paper honeycomb was soaked for about 10 minutes with an activation solution with a concentration of nickel acetate (g): sodium hypophosphite (g): water (ml) = 1:1:30, and then heat-treated at 200 °C for 60 minutes , and then rinsed with deionized water to remove the residual activation solution.

(4) Electroless iron nickel plating

The activated aramid paper honeycomb was electroless plated with iron and nickel in an alkaline solution at 90°C, wherein the composition and process conditions of the electroless iron and nickel plating solution: nickel hypophosphite 0.06mol/L, ferrous ammonium sulfate hexahydrate 0.04mol/L, sodium borohydride 0.005mol/L, pH value 9.0, temperature value 90℃, 60min.

Example 4:

(1) Cleaning

Put the aramid paper honeycomb (300mm*300mm*25mm) in the alkaline solution, treat it at 50℃ and the ultrasonic power is 170W for 10min, remove the impurities on the surface of the inner hole wall of the honeycomb, and then rinse the surface of the material with water to remove the impurities. Residual alkaline solution, the alkaline solution contains: 20g/L NaOH and 1g/L OP emulsifier.

(2) Micro-etching

Micro-etching is prepared by using hydrogen peroxide and sulfuric acid with a mass fraction of 98.3% and a volume ratio of 1:4. Put the washed aramid paper honeycomb in the micro-etching solution for about 5 minutes, take it out, wash it with water, rinse the surface with deionized water, rinse the surface with deionized water, and dry it (105℃, 1.5h).

(3) Activation

The micro-etched aramid paper honeycomb was soaked for about 10 minutes with an activation solution with a concentration of nickel acetate (g): sodium hypophosphite (g): water (ml) = 1:1:30, and then heat-treated at 200 °C for 40 minutes , and then rinsed with deionized water to remove the residual activation solution.

(4) Electroless iron nickel plating

The activated aramid paper honeycomb was electroless plated with iron and nickel in an alkaline solution at 90°C, wherein the composition and process conditions of the electroless iron and nickel plating solution: nickel hypophosphite 0.06mol/L, ferrous ammonium sulfate hexahydrate 0.06mol/L, sodium borohydride 0.01mol/L, sodium fluoride 0.005mol/L, pH value 10.0, temperature value 90°C, 60min.

Example 5:

(1) Cleaning

Put the aramid paper honeycomb (300mm*300mm*30mm) in the alkaline solution, treat it at 50℃ and the ultrasonic power is 160W for 10min to remove the impurities on the surface of the inner hole wall of the honeycomb, and then rinse the surface of the material with water to remove the impurities. Residual alkaline solution, the alkaline solution contains: 10g/L NaOH and 1g/L OP emulsifier.

(2) Micro-etching

Micro-etching is prepared by using hydrogen peroxide and sulfuric acid with a mass fraction of 98.3% and a volume ratio of 1:4. Put the washed aramid paper honeycomb in the micro-etching solution for about 5 minutes, take it out, wash it with water, rinse the surface with deionized water, rinse the surface with deionized water, and dry it (105℃, 1.5h).

(3) Activation

The micro-etched aramid paper honeycomb was soaked for about 10 minutes with an activation solution with a concentration of nickel acetate (g): sodium hypophosphite (g): water (ml) = 1:1:30, and then heat-treated at 200 °C for 60 minutes , and then rinsed with deionized water to remove the residual activation solution.

(4) Electroless iron nickel plating

The activated aramid paper honeycomb was electroless plated with iron and nickel in an alkaline solution at 90°C, wherein the composition and process conditions of the electroless iron and nickel plating solution: nickel hypophosphite 0.06mol/L, ferrous ammonium sulfate hexahydrate 0.04mol/L, sodium borohydride 0.005mol/L, pH value 11.5, temperature value 90℃, 60min.

Example 6:

(1) Cleaning

Put the aramid paper honeycomb (300mm*300mm*40mm) in the alkaline solution, treat it at 50℃ and the ultrasonic power is 200W for 10min, remove the impurities on the surface of the inner hole wall of the honeycomb, and then rinse the surface of the material with water to remove the impurities. Residual alkaline solution, the alkaline solution contains: 30g/L NaOH and 2g/L OP emulsifier.

(2) Micro-etching

Micro-etching is prepared by using hydrogen peroxide and sulfuric acid with a mass fraction of 98.3% and a volume ratio of 1:4. Put the washed aramid paper honeycomb in the micro-etching solution for about 5 minutes, take it out, wash it with water, rinse the surface with deionized water, rinse the surface with deionized water, and dry it (105℃, 1.5h).

(3) Activation

The micro-etched aramid paper honeycomb was soaked for about 10 minutes with an activation solution with a concentration of nickel acetate (g): sodium hypophosphite (g): water (ml) = 1:1:30, and then heat-treated at 200 °C for 60 minutes , and then rinsed with deionized water to remove the residual activation solution.

(4) Electroless iron nickel plating

The activated aramid paper honeycomb was electroless plated with iron and nickel in an alkaline solution at 90°C, wherein the composition and process conditions of the electroless iron and nickel plating solution: nickel hypophosphite 0.06mol/L, ferrous ammonium sulfate hexahydrate 0.06mol/L, sodium borohydride 0.01mol/L, pH value 11.0, temperature value 90℃, 60min.

Example 7

The difference from Example 1 is that the concentration of OP emulsifier in the cleaning step is 3 g/L.

Example 8

The difference from Example 1 is that the ultrasonic power in the cleaning step is 50W.

Example 9

The difference from Example 1 is that the ultrasonic time in the cleaning step is 5 min.

Example 10

The difference from Example 1 is that the ultrasonic time in the cleaning step is 30 min.

Example 11

The difference from Example 1 is that the alkaline washing temperature in the cleaning step is 30°C.

Example 12

The difference from Example 1 is that the alkaline washing temperature in the cleaning step is 70°C.

Example 13

The difference from Example 1 is that the volume ratio of hydrogen peroxide and sulfuric acid in the micro-etching step is 1:2.

Example 14

The difference from Example 1 is that the micro-etching time in the micro-etching step is 3 min.

Example 15

The difference from Example 1 is that the micro-etching time in the micro-etching step is 10 min.

Example 16

The difference from Example 1 is that an activation solution with a concentration of nickel acetate (g):sodium hypophosphite (g):water (ml)=1:0.5:30 is used in the activation step.

Example 17

The difference from Example 1 is that an activation solution with a concentration of nickel acetate (g):sodium hypophosphite (g):water (ml)=1:1.5:30 is used in the activation step.

Example 18

The difference from Example 1 is that the sodium hypophosphite is replaced with an equal weight of glucose in the activation step.

Example 19

The difference from Example 1 is that sodium hypophosphite is replaced with an equal weight of acetaldehyde in the activation step.

Example 20

The difference from Example 1 is that the immersion was performed for 5 min during the activation treatment.

Example 21

The difference from Example 1 is that the heat treatment temperature during the activation treatment is 205°C.

Example 22

The difference from Example 1 is that the heat treatment temperature during the activation treatment is 195°C.

Example 23

The difference from Example 1 is that the heat treatment time during the activation treatment is 30 min.

Example 24

The difference from Example 1 is that the nickel hypophosphite is replaced with equal concentration nickel sulfate in the electroless iron-nickel plating step.

Example 25

The difference from Example 1 is that in the electroless iron-nickel plating step, nickel acetate of equal concentration is used instead of nickel hypophosphite.

Example 26

The difference from Example 1 is that the concentration of nickel hypophosphite in the electroless iron-nickel plating step is 0.04 mol/L.

Example 27

The difference from Example 1 is that the concentration of nickel hypophosphite in the electroless nickel iron plating step is 0.09 mol/L.

Example 28

The difference from Example 1 is that the same concentration of borane is used instead of sodium borohydride in the electroless iron-nickel plating step.

Example 29

The difference from Example 1 is that the equal concentration of hypophosphite is used instead of sodium borohydride in the electroless iron-nickel plating step.

Example 30

The difference from Example 1 is that the concentration of ferrous ammonium sulfate hexahydrate in the electroless nickel-iron plating step is 0.01 mol/L.

Example 31

The difference from Example 1 is that the electroless plating treatment time is 30 min.

Example 32

The difference from Example 1 is that the concentration of sodium fluoride in the electroless iron-nickel plating step is 0.001 mol/L.

Example 33

The difference from Example 1 is that in the electroless iron-nickel plating step, sodium fluoride is replaced with equal concentration of boron aminoacetic acid.

Example 34

The difference from Example 1 is that sodium fluoride is replaced with equal concentration malonic acid in the electroless iron-nickel plating step.

Example 35

(1) Cleaning

Put the aramid paper honeycomb (300mm*300mm*5mm) in the alkaline solution, treat it at 50℃ and the ultrasonic power is 120W for 10min, remove the impurities on the surface of the inner hole wall of the honeycomb, and then rinse the surface of the material with water to remove the impurities. Residual alkaline solution, the alkaline solution contains: 20g/L NaOH and 2g/L OP emulsifier.

(2) Activation

The micro-etched aramid paper honeycomb was soaked for about 10 minutes with an activation solution with a concentration of nickel acetate (g): sodium hypophosphite (g): water (ml) = 1:1:30, and then heat-treated at 200 °C for 60 minutes , and then rinsed with deionized water to remove the residual activation solution.

(3) Electroless iron nickel plating

The activated aramid paper honeycomb was electroless plated with iron and nickel in an alkaline solution at 90°C, wherein the composition and process conditions of the electroless iron and nickel plating solution: nickel hypophosphite 0.06mol/L, ferrous ammonium sulfate hexahydrate 0.04mol/L, sodium borohydride 0.005mol/L, sodium fluoride 0.005mol/L, pH value 9.0, temperature value 90°C, treatment time 60min.

Example 36

The difference from Example 1 is that in the activation step, the heat treatment temperature is 220°C.

Example 37

The difference from Example 1 is that in the activation step, the heat treatment temperature is 180°C.

Example 38

The difference from Example 1 is that in the activation step, the heat treatment time is 15 min.

Example 39

The difference from Example 1 is that in the activation step, the heat treatment time is 75 min.

Example 40

The difference from Example 1 is that in the electroless iron-nickel plating step, the concentration of nickel hypophosphite is 0.02 mol/L.

Example 41

The difference from Example 1 is that in the electroless iron-nickel plating step, the concentration of nickel hypophosphite is 0.13 mol/L.

Example 42

The difference from Example 1 is that in the electroless iron-nickel plating step, the concentration of ferrous ammonium sulfate hexahydrate is 0.09 mol/L.

The properties of the metallized aramid honeycomb materials prepared in the above examples were tested.

(1) Corrosion resistance test:

Specific test content: observe the distribution of the metal layer on the honeycomb hole wall, and then conduct the corrosion resistance test through the salt spray test. And observe whether it is easy to fall off and the corrosion products of the material are loose. For example, when evaluating the corrosion resistance of different materials through the salt spray test, the weight loss method is usually used.

Gravimetric method is the most basic and most effective and credible quantitative evaluation method in the study of material corrosion resistance. Although the gravimetric method has the disadvantage of not being able to study the corrosion mechanism of materials, by measuring the change in the weight of the material before and after corrosion, the corrosion resistance of the material can be more accurately and credibly characterized. Because of this, it has been widely used in corrosion research and is the basis for the identification and comparison of many modern electrochemical, physical and chemical analytical evaluation methods. The weight loss method can usually be considered.

The corrosion resistance of the material is characterized by the salt spray test combined with the weight loss test. According to the requirements of ASTMB117, the sample is placed at an inclination angle of 15-30 degrees, and 5% NaCl solution is used for atomization and spraying, and the test temperature is 35 °C. Salt spray experiment requirement

(2) Compressive strength test

Take GB/T 1453-2005 test method as an example:

A. Sample preparation: cut into sample honeycombs between 60mm*60mm*5mm and 60mm*60mm*40mm.

B. Testing equipment: Universal material testing machine.

C. Compression fixture: A fixed flat platen and a platen with a spherical seat (automatic centering) should be used to introduce force into the specimen, the platen can be well centered and no eccentric load is applied, and the surface of the platen should exceed Specimen shape. If the platen hardness is insufficient or to protect the platen surface, a stiffer flat plate (parallel to the surface) can be inserted between the clamp and each end face of the corresponding platen.

Test method: When testing the flat compressive strength, adjust the spherical support so that the upper pad is parallel to the lower pressing piece of the testing machine, and then load it uniformly and continuously until it fails, read the failure load, and record the failure form. The recommended loading speed is 0.5mm/min.

E. Failure mode: Uniform failure of the sample honeycomb is the only acceptable failure mode, compression failure limited to one corner or one side is ineffective.

F. Data processing: keep 3 decimal places, limit strength, P=F/A. where P is the uncompressed strength, MPa; F is the ultimate load before failure, N; A is the cross-sectional area of the specimen, mm ² .

(3) Shielding energy efficiency test

According to GJB6190-2008, the shielding effectiveness of shielding materials is tested in the electromagnetic compatibility test shielding room in the range of 10MHz to 10GHz. test. Due to the amplitude value (unit: dB) displayed by the spectrum analyzer, the shielded room can directly measure the receiving field strength with and without shielding material, and the shielding effectiveness of the shielding material can be obtained by subtracting the two.

The above test results are recorded in Table 1.

Table 1

From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the following technical effects:

For the preparation method of the metallized aramid honeycomb material of the present application, firstly, cleaning is performed to remove solid small particles of impurities such as dust attached to the surface of the aramid fiber honeycomb and stains such as mineral oil or grease adhering to the pore walls, and secondly, an activation treatment is performed, It makes it easier to deposit Fe-Ni coating on the aramid honeycomb surface. Finally, chemical plating is performed to form a uniform iron-nickel coating on the surface of the active aramid honeycomb, which realizes the metallization of the aramid paper honeycomb. It can be seen from the above description that the preparation method of the metallized aramid honeycomb material of the present application is simple, and the metallization of the aramid paper honeycomb can be completed by cleaning, activation and electroless plating, and the result is good corrosion resistance, good air permeability, Metallized aramid paper honeycomb material with high plane compressive strength and excellent shielding properties.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A preparation method of a metallized aramid honeycomb material is characterized by comprising the following steps:

step S1, cleaning the aramid fiber honeycomb to obtain a clean aramid fiber honeycomb;

step S2, carrying out activation treatment on the clean aramid fiber honeycomb to obtain an active aramid fiber honeycomb;

and step S3, placing the active aramid honeycomb into a chemical iron and nickel plating solution for chemical plating so as to form an iron and nickel plating layer on the inner surface of the active aramid honeycomb.

2. The preparation method according to claim 1, wherein the step S1 comprises sequentially performing alkali washing and water washing on the aramid fiber honeycomb to obtain the clean aramid fiber honeycomb.

3. The preparation method according to claim 2, wherein the alkaline solution used for alkaline washing comprises NaOH with a concentration of 10-30 g/L and OP emulsifier with a concentration of 1-3 g/L, preferably the ultrasonic treatment is performed in the alkaline process, further preferably the ultrasonic power is 50-200W, the ultrasonic treatment time is 5-30 min, and preferably the alkaline washing is performed at 30-70 ℃.

4. The method for preparing a composite material according to claim 1, wherein the step S2 includes: and sequentially carrying out infiltration treatment and heat treatment on the clean aramid fiber honeycomb in an activation solution to obtain the active aramid fiber honeycomb, wherein the activation solution comprises nickel acetate, a first reducing agent and water in a ratio of 1g to 0.5-1.5 g to 20-40 mL, and preferably the first reducing agent is selected from one or more of sodium hypophosphite, glucose, formaldehyde, acetaldehyde and sodium hypophosphite.

5. The method according to claim 4, wherein the soaking treatment is performed for 5 to 10min, preferably at 195 to 205 ℃ for 30 to 60 min.

6. The preparation method according to claim 4, wherein the step S2 further comprises a surface corrosion process of the clean aramid honeycomb before the infiltration treatment, preferably the surface corrosion process comprises:

and carrying out corrosion treatment on the clean aramid fiber by using a corrosion solution, wherein the corrosion solution comprises hydrogen peroxide and sulfuric acid in a volume ratio of 1: 2-4, preferably, the corrosion treatment time is 3-10 min, and preferably, the mass concentration of the sulfuric acid is 90-99%.

7. The preparation method according to claim 1, wherein in the step S3, the electroless iron-nickel plating solution includes a soluble nickel salt, a soluble ferrous salt and a second reducing agent, wherein the soluble nickel salt is selected from any one or more of nickel sulfate, nickel acetate and nickel hypophosphite, the soluble ferrous salt is selected from any one or more of ammonium ferrous sulfate hexahydrate and ferrous chloride tetrahydrate, and the second reducing agent is selected from any one or more of hypophosphite, sodium borohydride, borane and hydrazine; preferably, the concentration of the soluble nickel salt is 0.04-0.09 mol/L, the concentration of the soluble ferrous salt is 0.01-0.06 mol/L, and the concentration of the second reducing agent is 0.005-0.01 mol/L; preferably, the pH value of the electroless iron-nickel plating solution is 8.0-11.5, preferably, the electroless plating temperature is 90 ℃ and the time is 30-60 min, preferably, the electroless iron-nickel plating solution further comprises a catalyst, wherein the catalyst is any one or more selected from malonic acid, succinic acid, glycine, propionic acid and sodium fluoride, and the concentration of the catalyst is 0.001-0.005 mol/L.

8. A metallized aramid honeycomb material characterized by being prepared by the preparation method of any one of claims 1 to 7.

9. The metallized aramid fiber honeycomb material is characterized by comprising an aramid fiber honeycomb substrate and an iron-nickel coating, wherein the iron-nickel coating is arranged on the inner surface and the outer surface of the aramid fiber honeycomb substrate, the mass ratio of the aramid fiber honeycomb substrate to the iron-nickel coating is preferably 100-10: 1, the thickness of the iron-nickel coating is preferably 10-30 micrometers, the iron-nickel coating contains phosphorus, and the mass ratio of iron, nickel and phosphorus is preferably 0.4-0.9: 0.1-0.6: 0.05-0.1.

10. An electromagnetic shielding structure comprising an electromagnetic shielding honeycomb core material, wherein the electromagnetic shielding honeycomb core material is the metalized aramid honeycomb material of claim 8 or 9.