Metal composite microsphere with wave-absorbing characteristic as well as preparation method and application of metal composite microsphere

Abstract

The invention discloses a metal composite microsphere with a wave-absorbing characteristic as well as a preparation method and application of the metal composite microsphere. The structure of the composite microsphere comprises an inner core and an outer core which are sequentially arranged from inside to outside, wherein the inner core is selected from a carbon microsphere; the shell layer comprises a magnetic metal spherical shell layer and a magnetic metal sulfide spherical shell layer coated on the magnetic metal spherical shell layer; wherein the carbon microspheres are located in a cavity defined by the magnetic metal spherical shell layer. The metal composite microsphere has good electromagnetic wave absorbing property and can be well applied to microwave absorption, catalysis, adsorption or wastewater treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of powder materials, and more specifically to a metal composite microsphere with wave absorbing properties, a preparation method and application thereof. Background Art

[0002] With the rapid development of wireless communication, broadcasting and radar technology, electromagnetic waves have been widely used in modern production and life. While this brings great convenience, the ubiquitous electromagnetic waves also pose a huge threat to the stable operation of high-end electronic equipment and human health. In order to prevent electromagnetic waves from interfering with the operation of equipment and damaging organisms, it is an effective method to absorb and shield electromagnetic waves through appropriate materials. Among them, electromagnetic wave absorbing materials are particularly preferred, because compared with the shielding under the reflection mechanism, the effective absorption of incident electromagnetic waves by absorbing materials can avoid secondary pollution caused by direct interface reflection. So far, scientific research and technical developers have conducted a lot of research on the potential of many materials with electromagnetic response characteristics such as dielectric, conductive, and magnetic as high-performance absorbing materials. Among them, magnetic metals have received special attention for their wide sources, electromagnetic response and high designability. Especially after being designed into micro-nano sizes and hollow structures, the size effect and hollow cavity of magnetic metals will further improve performance. In particular, the existence of the hollow structure not only brings more abundant heterogeneous interfaces and thus improves performance, but also effectively reduces the density of magnetic metal absorbing materials, meeting the common design needs for lightweight of current high-end electronic products and advanced equipment.

[0003] However, similar to other magnetic metal micro-nano structures, micro-nano hollow microstructures also have a large specific surface area (surface atomic ratio), which inevitably leads to the oxidation and agglomeration of these micro-nano magnetic metal materials while improving electromagnetic functions. Most magnetic metal oxides do not have magnetic properties and have low electrical conductivity. Their existence not only reduces the proportion of effective zero-valent metal atoms and reduces the magnetic response, but also seriously affects the formation of local conductive networks, which is not conducive to enhancing the absorption of electromagnetic waves by means of leakage conductance loss. Therefore, designing a hollow structure and obtaining a magnetic metal hollow microsphere while performing a composite design of a magnetic metal shell is an effective way to improve stability and electromagnetic wave absorption characteristics. On the other hand, conventional magnetic metal hollow microspheres are mostly gas cavity structures, which can reduce density and bring about certain scattering effects, but the internal cavity shows wave-transmitting characteristics for electromagnetic waves and cannot bring about more loss mechanisms.

[0004] Therefore, it is still a great challenge or a problem to be solved urgently to coordinately design the outer surface of the spherical shell and the internal cavity of magnetic metal hollow microspheres and construct a new composite structure to achieve performance enhancement. Summary of the invention

[0005] Based on the above facts, the purpose of the present invention is to provide a metal composite microsphere with wave absorbing properties and a preparation method and application thereof, so as to at least solve the above problems.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In one aspect, the present invention provides a metal composite microsphere having wave absorbing properties, wherein the structure of the composite microsphere comprises:

[0008] A core selected from carbon microspheres;

[0009] The shell layer comprises a magnetic metal spherical shell layer and a magnetic metal sulfide spherical shell layer coated on the magnetic metal spherical shell layer;

[0010] Wherein, the carbon microspheres are located in the cavity formed by the magnetic metal spherical shell layer.

[0011] Furthermore, in the composite microspheres, the content of carbon microspheres is 10-45wt%, the content of magnetic metal spherical shells is 8-65wt%, and the content of magnetic metal sulfide spherical shells is 25-65wt%, calculated by mass percentage.

[0012] Furthermore, the magnetic metals in the magnetic metal spherical shell layer and the magnetic metal sulfide spherical shell layer are independently selected from one or more of iron, cobalt and nickel.

[0013] Furthermore, the carbon microspheres are movable in the cavity.

[0014] Furthermore, the diameter of the composite microspheres is 2.6-12 μm, the diameter of the carbon microspheres is 2-10 μm, and the distance between the carbon microspheres and the magnetic metal spherical shell is 0.18-0.21 μm.

[0015] In another aspect, the present invention provides a method for preparing the metal composite microspheres as described above, comprising the following steps:

[0016] Colloidal carbon spheres were prepared by hydrothermal method;

[0017] Pretreating the colloidal carbon spheres;

[0018] Directed auxiliary assembly of magnetic metal spherical shells on the surface of pretreated colloidal carbon spheres;

[0019] The colloidal carbon spheres assembled with the magnetic metal spherical shells are subjected to a sulfurization treatment to obtain the metal composite microspheres.

[0020] It is found in the preparation method of the present invention that only the colloidal carbon spheres prepared by the hydrothermal method can shrink in volume after subsequent vulcanization treatment to form a structure with a hollow cavity, and the core of the obtained carbon microspheres is located in the hollow cavity.

[0021] Furthermore, the method for preparing colloidal carbon spheres by the hydrothermal method comprises the following steps:

[0022] The carbon source aqueous solution is mixed with a surfactant, and a hydrothermal reaction is carried out. The intermediate carbon microspheres are obtained through filtering, washing and drying.

[0023] Furthermore, the carbon source is selected from one or more of glucose, fructose, sucrose, maltose, starch and citric acid.

[0024] Furthermore, the concentration of the carbon source in the carbon source aqueous solution is 0.1-1 mol / L.

[0025] Furthermore, the surfactant is selected from one of cetyltrimethylammonium bromide and polyvinylpyrrolidone.

[0026] Furthermore, the temperature of the hydrothermal reaction is 180-220° C., and the time is 10-15 hours.

[0027] Furthermore, the pretreatment method comprises the following steps:

[0028] The colloidal carbon spheres are sequentially subjected to surface coupling treatment, sensitization treatment and activation treatment to obtain the colloidal carbon spheres.

[0029] Furthermore, the surface coupling treatment is carried out in a surface treatment liquid, wherein the solute of the surface treatment liquid is a coupling agent, and the solvent is anhydrous ethanol and / or distilled water, more preferably a mixture of anhydrous ethanol and distilled water in a volume ratio of 1:1-1:5.

[0030] Furthermore, the temperature of the surface coupling treatment is 20-70°C, more preferably 30-50°C.

[0031] Furthermore, the sensitization treatment is carried out in a sensitizing solution, wherein the sensitizing solution is a stannous chloride aqueous solution with a concentration of 0.03-0.3 mol / L.

[0032] Furthermore, the activation treatment is carried out in an active solution, wherein the activation solution is a noble metal ion solution with a concentration of 0.002-0.2 mol / L, wherein the noble metal is preferably one or more of palladium, gold, platinum and rhodium.

[0033] Furthermore, the method also includes a reduction treatment step after the pretreatment to reduce the noble metal ions modified during the activation treatment to metals to impart catalytic activity. Exemplarily, the reduction treatment step includes the following steps: placing the pretreated colloidal carbon spheres in a reducing solution (such as an aqueous sodium hypophosphite solution, preferably with a concentration of 0.4 mol / L), stirring evenly at room temperature, filtering, and drying. Among them, the ratio of the pretreated colloidal carbon spheres to the reducing solution is preferably 1 g / 20 mL.

[0034] In the preparation method of the present invention, the pretreatment method affects the structural stability and density of the magnetic metal shell assembled on the surface of the colloidal carbon sphere, and further affects the electromagnetic properties of the obtained composite microspheres. Only by performing surface coupling treatment, sensitization treatment and activation treatment in sequence can composite microspheres with stable structure and good electromagnetic properties be obtained.

[0035] Furthermore, the method for directional auxiliary assembly of magnetic metal spherical shells on the surface of pretreated colloidal carbon spheres comprises the following steps:

[0036] The pretreated colloidal carbon spheres are placed in an auxiliary deposition solution containing magnetic metal ions, stirred in a water bath, filtered, dried, and agglomerates are screened out to obtain the obtained colloid carbon spheres.

[0037] Furthermore, the auxiliary deposition solution comprises a magnetic metal ion source salt, a stabilizer, a reducing agent and a pH adjuster.

[0038] Furthermore, the reducing agent contained is an organic or inorganic reducing agent that can reduce the corresponding magnetic metal ions to metal elements.

[0039] Furthermore, the magnetic metal ion source salt is selected from sulfates, chlorides or organic acid salts of magnetic metals, and the concentration is 10-60 g / L.

[0040] Furthermore, the stabilizer is selected from one or more of ammonium sulfate, potassium sodium tartrate and EDTA, and the concentration is 20-100 g / L.

[0041] Furthermore, the pH adjuster is selected from inorganic bases.

[0042] Furthermore, the pH of the auxiliary deposition solution is 9-11.

[0043] Furthermore, the temperature of the water bath is 50-85°C.

[0044] Furthermore, the addition amount of the pretreated colloidal carbon spheres is 0.0025-0.01 g / mL.

[0045] Furthermore, the vulcanization method comprises the following steps:

[0046] The colloidal carbon spheres assembled with magnetic metal spherical shells are mixed with sulfur powder and subjected to heat treatment in a reducing or inert atmosphere to obtain the colloidal carbon spheres.

[0047] Furthermore, the mass ratio of the colloidal carbon spheres assembled with magnetic metal spherical shells to the sulfur powder is 1.5:1-20:1.

[0048] Furthermore, the heat treatment temperature is 450-550°C and the time is 2-4h.

[0049] Furthermore, the atmosphere is a hydrogen / argon mixed gas, nitrogen or argon atmosphere.

[0050] In another aspect, the present invention provides a wave absorbing agent, characterized in that it is prepared from a raw material comprising the metal composite microspheres as described above.

[0051] In another aspect, the present invention provides use of the metal composite microspheres as described above in microwave absorption, catalysis, adsorption or wastewater treatment.

[0052] The beneficial effects of the present invention are as follows:

[0053] In the metal composite microspheres provided by the present invention, the movable carbon microsphere core can controllably fill the hollow structure inside the magnetic metal shell, thereby improving the effective scattering and loss of incident electromagnetic waves; the outer metal sulfide shell layer gives the material controllable dielectric and conductivity losses, and optimizes the impedance matching characteristics of the material; in addition, the outer magnetic metal sulfide shell layer can also prevent the magnetic metal from directly contacting the air, thereby preventing the magnetic metal from being oxidized. The metal composite microspheres have a wide effective absorption band (for example, the maximum effective absorption band can be between 3.4-5.4 GHz, and the frequency range of the maximum effective absorption band can be 6.5-12 GHz), and the frequency corresponding to the strongest reflection loss coefficient of the material can be 8.5-9.5 GHz.

[0054] In the preparation method of the metal composite microsphere provided by the present invention, the functionality can be regulated by the composition and structural design of the metal and metal sulfide spherical shells. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0056] Figure 1 A schematic diagram showing the structure of an exemplary metal composite microsphere of the present invention is shown in the figure.

[0057] Figure 2 A schematic diagram of an exemplary preparation process of exemplary metal composite microspheres of the present invention is shown.

[0058] Figure 3A low-magnification scanning electron microscope (SEM) image of the metal composite microspheres obtained in Example 2 is shown.

[0059] Figure 4 The X-ray diffraction pattern of the magnetic metal composite microspheres obtained in Example 2 is shown. DETAILED DESCRIPTION

[0060] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. Similar components in the accompanying drawings are represented by the same reference numerals. It should be understood by those skilled in the art that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0061] In the embodiment of the present invention, the schematic diagram of the structure of the exemplary metal composite microsphere is as follows Figure 1 shown.

[0062] An exemplary schematic diagram of the preparation process of the metal composite microspheres is shown in Figure 2 As shown. Among them, Figure 2 In the figure, A is hydrothermal treatment, B is metal assembly, and C is sulfidation treatment. Figure 2 It is not shown in the figure, but the colloidal carbon spheres are pre-treated before assembling the magnetic metal shells.

[0063] Example 1

[0064] The preparation of metal composite microspheres with wave absorbing properties, the specific implementation scheme is as follows:

[0065] 1) Preparation of colloidal carbon spheres: 15 g of glucose was dissolved in 150 mL of distilled water and stirred evenly, then 0.4 g of CTAB was added and stirred until all dissolved, and then the mixed solution was transferred to a hydrothermal reactor and reacted at 180° C. for 12 hours, then filtered, washed, and dried to obtain colloidal carbon spheres;

[0066] 2) Surface treatment of colloidal carbon spheres: mix anhydrous ethanol, distilled water, and 3-aminopropyltriethoxysilane in a volume ratio of 30:10:2, add colloidal carbon spheres in a ratio of 5 g / 100 mL (5 g microspheres per 100 mL solution), stir in a water bath at 40° C. for 30 min, filter, dry and set aside;

[0067] 3) Colloidal carbon sphere sensitization treatment: the microspheres obtained in step 2) were treated in a 0.1 mol / L stannous chloride aqueous solution at a ratio of 1 g / 20 mL, stirred at 40° C., and filtered;

[0068] 4) Activation treatment of colloidal carbon spheres: the microspheres obtained in step 3) were treated in a ratio of 1 g / 30 mL in a 0.01 mol / L palladium chloride solution, stirred at 45° C., and filtered;

[0069] 5) Colloidal carbon sphere reduction treatment: The microspheres obtained in step 4) are treated in a 0.4 mol / L sodium hypophosphite aqueous solution at a ratio of 1 g / 20 mL, stirred at room temperature, filtered, and dried for later use;

[0070] 6) Preparation of colloidal carbon sphere-metal composite microspheres: The microspheres obtained in step 5) were treated in a ratio of 1 g / 270 mL in a metal ion mixed solution containing 31 g / L cobalt sulfate, 42 g / L sodium hypophosphite, 85 g / L potassium sodium tartrate, 40 g / L ammonium sulfate, pH ≈ 9.0 (adjusted by ammonia water), stirred in a water bath at 70° C. for 20 min, filtered, and dried for later use;

[0071] 7) The microspheres obtained in step 6) were mixed with sublimed sulfur at a mass ratio of 7.3:1, and then subjected to a sulfurization reaction in an argon atmosphere at a sulfurization temperature of 500° C., a heating rate of 10° C. / min, and a holding time of 3 h to obtain the target product.

[0072] The diameter of the carbon microsphere inner core of the metal composite microsphere obtained in this example is 5.1 μm, the cavity spacing (the distance between the inner core and the inner surface of the metal shell) is 0.20 μm, and the mass percentages of the magnetic metal sulfide shell layer, the magnetic metal shell layer and the carbon microsphere inner core are 19.7%, 51.1% and 29.2% respectively.

[0073] Example 2

[0074] The preparation of metal composite microspheres with wave absorbing properties, the specific implementation scheme is as follows:

[0075] 1) Preparation of colloidal carbon spheres: 15 g of glucose was dissolved in 150 mL of distilled water and stirred evenly, then 0.4 g of CTAB was added and stirred until all dissolved, and then the mixed solution was transferred to a hydrothermal reactor and reacted at 180° C. for 12 hours, then filtered, washed, and dried to obtain colloidal carbon spheres;

[0076] 2) Surface treatment of colloidal carbon spheres: mix anhydrous ethanol, distilled water, and 3-aminopropyltriethoxysilane in a volume ratio of 30:10:2, add colloidal carbon spheres in a ratio of 5 g / 100 mL (5 g microspheres per 100 mL solution), stir in a water bath at 40° C. for 30 min, filter, dry and set aside;

[0077] 3) Colloidal carbon sphere sensitization treatment: the microspheres obtained in step 2) were treated in a 0.1 mol / L stannous chloride aqueous solution at a ratio of 1 g / 20 mL, stirred at 40° C., and filtered;

[0078] 4) Activation treatment of colloidal carbon spheres: the microspheres obtained in step 3) were treated in a ratio of 1 g / 30 mL in a 0.01 mol / L palladium chloride solution, stirred at 45° C., and filtered;

[0079] 5) Colloidal carbon sphere reduction treatment: The microspheres obtained in step 4) are treated in a 0.4 mol / L sodium hypophosphite aqueous solution at a ratio of 1 g / 20 mL, stirred at room temperature, filtered, and dried for later use;

[0080] 6) Preparation of colloidal carbon sphere-metal composite microspheres: The microspheres obtained in step 5) were treated in a mixed solution of metal ions containing 31 g / L cobalt sulfate, 42 g / L sodium hypophosphite, 85 g / L potassium sodium tartrate, 40 g / L ammonium sulfate, pH ≈ 9.0 (adjusted by ammonia water) at a ratio of 1 g / 200 mL, stirred in a water bath at 60° C. for 20 min, filtered, and dried for later use;

[0081] 7) The microspheres obtained in step 6) were mixed with sublimed sulfur at a mass ratio of 16.1:1, and then subjected to a sulfurization reaction in an argon atmosphere at a temperature of 480° C., a heating rate of 10° C. / min, and a holding time of 3 h to obtain the target product.

[0082] The carbon microsphere core of the metal composite microspheres obtained in this example has a diameter of 5.1 μm, a cavity spacing (the distance between the core and the inner surface of the shell) of 0.19 μm, and the mass percentages of the magnetic metal sulfide shell layer, the magnetic metal shell layer and the carbon microsphere core are 9.3%, 54.6% and 36.1% respectively.

[0083] Example 3

[0084] The preparation of metal composite microspheres with wave absorbing properties, the specific implementation scheme is as follows:

[0085] 1) Preparation of colloidal carbon spheres: 15 g of glucose was dissolved in 150 mL of distilled water and stirred evenly, then 0.4 g of CTAB was added and stirred until all dissolved, and then the mixed solution was transferred to a hydrothermal reactor and reacted at 180° C. for 12 hours, then filtered, washed, and dried to obtain colloidal carbon spheres;

[0086] 2) Surface treatment of colloidal carbon spheres: mix anhydrous ethanol, distilled water, and 3-aminopropyltriethoxysilane in a volume ratio of 30:10:2, add colloidal carbon spheres in a ratio of 5 g / 100 mL (5 g microspheres per 100 mL solution), stir in a water bath at 40° C. for 30 min, filter, dry and set aside;

[0087] 3) Colloidal carbon sphere sensitization treatment: the microspheres obtained in step 2) were treated in a 0.1 mol / L stannous chloride aqueous solution at a ratio of 1 g / 20 mL, stirred at 40° C., and filtered;

[0088] 4) Activation treatment of colloidal carbon spheres: the microspheres obtained in step 3) were treated in a ratio of 1 g / 30 mL in a 0.01 mol / L palladium chloride solution, stirred at 45° C., and filtered;

[0089] 5) Colloidal carbon sphere reduction treatment: The microspheres obtained in step 4) are treated in a 0.4 mol / L sodium hypophosphite aqueous solution at a ratio of 1 g / 20 mL, stirred at room temperature, filtered, and dried for later use;

[0090] 6) Preparation of colloidal carbon sphere-metal composite microspheres: The microspheres obtained in step 5) were treated in a mixed solution of metal ions containing 31 g / L cobalt sulfate, 42 g / L sodium hypophosphite, 85 g / L potassium sodium tartrate, 40 g / L ammonium sulfate, pH ≈ 9.0 (adjusted by ammonia water) at a ratio of 1 g / 330 mL, stirred in a water bath at 70° C. for 20 min, filtered, and dried for later use;

[0091] 7) The microspheres obtained in step 6) were mixed with sublimed sulfur at a mass ratio of 4.5:1, and then subjected to a vulcanization reaction in an argon atmosphere at a vulcanization temperature of 550° C., a heating rate of 10° C. / min, and a holding time of 3 h to obtain the target product.

[0092] The carbon microsphere core of the metal composite microspheres obtained in this example has a diameter of 5.1 μm, a cavity spacing (the distance between the core and the inner surface of the shell) of 0.21 μm, and the mass percentages of the magnetic metal sulfide shell layer, the magnetic metal shell layer and the carbon microsphere core are 30.2%, 45.8% and 24.0%, respectively.

[0093] Example 4

[0094] The preparation of metal composite microspheres with wave absorbing properties, the specific implementation scheme is as follows:

[0095] 1) Preparation of colloidal carbon spheres: 15 g of glucose was dissolved in 150 mL of distilled water and stirred evenly, then 0.4 g of CTAB was added and stirred until all dissolved, and then the mixed solution was transferred to a hydrothermal reactor and reacted at 180° C. for 12 hours, then filtered, washed, and dried to obtain colloidal carbon spheres;

[0096] 2) Surface treatment of colloidal carbon spheres: mix anhydrous ethanol, distilled water, and 3-aminopropyltriethoxysilane in a volume ratio of 30:10:2, add colloidal carbon spheres in a ratio of 5 g / 100 mL (5 g microspheres per 100 mL solution), stir in a water bath at 40° C. for 30 min, filter, dry and set aside;

[0097] 3) Colloidal carbon sphere sensitization treatment: the microspheres obtained in step 2) were treated in a 0.1 mol / L stannous chloride aqueous solution at a ratio of 1 g / 20 mL, stirred at 40° C., and filtered;

[0098] 4) Activation treatment of colloidal carbon spheres: the microspheres obtained in step 3) were treated in a ratio of 1 g / 30 mL in a 0.01 mol / L palladium chloride solution, stirred at 45° C., and filtered;

[0099] 5) Colloidal carbon sphere reduction treatment: The microspheres obtained in step 4) are treated in a 0.4 mol / L sodium hypophosphite aqueous solution at a ratio of 1 g / 20 mL, stirred at room temperature, filtered, and dried for later use;

[0100] 6) Preparation of colloidal carbon sphere-metal composite microspheres: The microspheres obtained in step 5) were treated in a ratio of 1 g / 330 mL in a metal ion mixed solution containing 22 g / L cobalt sulfate, 21 g / L nickel sulfate, 52 g / L sodium hypophosphite, 90 g / L potassium sodium tartrate, 50 g / L ammonium sulfate, pH ≈ 9.0 (adjusted by ammonia water), stirred in a water bath at 70°C for 20 min, filtered, and dried for later use;

[0101] 7) The microspheres obtained in step 6) were mixed with sublimed sulfur at a mass ratio of 8.1:1, and then subjected to a sulfurization reaction in an argon atmosphere at a sulfurization temperature of 450° C., a heating rate of 10° C. / min, and a holding time of 3 h to obtain the target product.

[0102] The carbon microsphere core of the metal composite microspheres obtained in this example has a diameter of 5.1 μm, a cavity spacing (the distance between the core and the inner surface of the shell) of 0.18 μm, and the mass percentages of the magnetic metal sulfide shell layer, the magnetic metal shell layer and the carbon microsphere core are 17.2%, 63.3% and 19.5% respectively.

[0103] Example 5

[0104] The preparation of metal composite microspheres with wave absorbing properties, the specific implementation scheme is as follows:

[0105] 1) Preparation of colloidal carbon spheres: 15 g of glucose was dissolved in 150 mL of distilled water and stirred evenly, then 0.4 g of CTAB was added and stirred until all dissolved, and then the mixed solution was transferred to a hydrothermal reactor and reacted at 180° C. for 12 hours, then filtered, washed, and dried to obtain colloidal carbon spheres;

[0106] 2) Surface treatment of colloidal carbon spheres: mix anhydrous ethanol, distilled water, and 3-aminopropyltriethoxysilane in a volume ratio of 30:10:2, add colloidal carbon spheres in a ratio of 5 g / 100 mL (5 g microspheres per 100 mL solution), stir in a water bath at 40° C. for 30 min, filter, dry and set aside;

[0107] 3) Colloidal carbon sphere sensitization treatment: the microspheres obtained in step 2) were treated in a 0.1 mol / L stannous chloride aqueous solution at a ratio of 1 g / 20 mL, stirred at 40° C., and filtered;

[0108] 4) Activation treatment of colloidal carbon spheres: the microspheres obtained in step 3) were treated in a ratio of 1 g / 30 mL in a 0.01 mol / L palladium chloride solution, stirred at 45° C., and filtered;

[0109] 5) Colloidal carbon sphere reduction treatment: The microspheres obtained in step 4) are treated in a 0.4 mol / L sodium hypophosphite aqueous solution at a ratio of 1 g / 20 mL, stirred at room temperature, filtered, and dried for later use;

[0110] 6) Preparation of colloidal carbon sphere-metal composite microspheres: The microspheres obtained in step 5) were treated at a ratio of 1 g / 100 mL in a metal ion mixed solution containing 22 g / L cobalt sulfate, 21 g / L nickel sulfate, 52 g / L sodium hypophosphite, 90 g / L potassium sodium tartrate, 50 g / L ammonium sulfate, pH ≈ 9.0 (adjusted by ammonia water), stirred in a water bath at 70° C. for 20 min, filtered, and dried for later use;

[0111] 7) The microspheres obtained in step 6) were mixed with sublimed sulfur at a mass ratio of 7.5:1, and then subjected to a sulfurization reaction in an argon atmosphere at a temperature of 470° C., a heating rate of 10° C. / min, and a holding time of 3 h to obtain the target product.

[0112] The carbon microsphere core of the metal composite microspheres obtained in this example has a diameter of 5.1 μm, a cavity spacing (the distance between the core and the inner surface of the shell) of 0.19 μm, and the mass percentages of the magnetic metal sulfide shell layer, the magnetic metal shell layer and the carbon microsphere core are 19.7%, 38.3% and 42% respectively.

[0113] Example 6

[0114] The preparation of metal composite microspheres with wave absorbing properties, the specific implementation scheme is as follows:

[0115] 1) Preparation of colloidal carbon spheres: 15 g of glucose was dissolved in 150 mL of distilled water and stirred evenly, then 0.4 g of CTAB was added and stirred until all dissolved, and then the mixed solution was transferred to a hydrothermal reactor and reacted at 180° C. for 12 hours, then filtered, washed, and dried to obtain colloidal carbon spheres;

[0116] 2) Surface treatment of colloidal carbon spheres: mix anhydrous ethanol, distilled water, and 3-aminopropyltriethoxysilane in a volume ratio of 30:10:2, add colloidal carbon spheres in a ratio of 5 g / 100 mL (5 g microspheres per 100 mL solution), stir in a water bath at 40° C. for 30 min, filter, dry and set aside;

[0117] 3) Colloidal carbon sphere sensitization treatment: the microspheres obtained in step 2) were treated in a 0.1 mol / L stannous chloride aqueous solution at a ratio of 1 g / 20 mL, stirred at 40° C., and filtered;

[0118] 4) Activation treatment of colloidal carbon spheres: the microspheres obtained in step 3) were treated in a ratio of 1 g / 30 mL in a 0.01 mol / L palladium chloride solution, stirred at 45° C., and filtered;

[0119] 5) Colloidal carbon sphere reduction treatment: the microspheres obtained in step 4) are treated in a 0.4 mol / L sodium hypophosphite aqueous solution at a ratio of 1 g / 20 mL, stirred at room temperature, filtered, dried and set aside;

[0120] 6) Preparation of colloidal carbon sphere-metal composite microspheres: The microspheres obtained in step 5) were treated in a mixed solution of metal ions containing 26 g / L cobalt sulfate, 26 g / L nickel sulfate, 60 g / L sodium hypophosphite, 100 g / L potassium sodium tartrate, 60 g / L ammonium sulfate, pH ≈ 9.5 (adjusted by ammonia water) at a ratio of 1 g / 360 mL, stirred in a water bath at 70°C for 30 min, filtered, and dried for later use;

[0121] 7) The microspheres obtained in step 6) were mixed with sublimed sulfur at a mass ratio of 1.9:1, and then subjected to a sulfurization reaction in an argon atmosphere at a sulfurization temperature of 500° C., a heating rate of 10° C. / min, and a holding time of 3 h to obtain the target product.

[0122] The carbon microsphere core of the metal composite microspheres obtained in this example has a diameter of 5.1 μm, a cavity spacing (the distance between the core and the inner surface of the shell) of 0.20 μm, and the mass percentages of the magnetic metal sulfide shell layer, the magnetic metal shell layer and the carbon microsphere core are 60.9%, 26.3% and 12.8% respectively.

[0123] Example 7

[0124] The preparation of metal composite microspheres with wave absorbing properties, the specific implementation scheme is as follows:

[0125] 1) Preparation of colloidal carbon spheres: 15 g of glucose was dissolved in 150 mL of distilled water and stirred evenly, then 0.4 g of CTAB was added and stirred until all dissolved, and then the mixed solution was transferred to a hydrothermal reactor and reacted at 180° C. for 12 hours, then filtered, washed, and dried to obtain colloidal carbon spheres;

[0126] 2) Surface treatment of colloidal carbon spheres: mix anhydrous ethanol, distilled water, and 3-aminopropyltriethoxysilane in a volume ratio of 30:10:2, add colloidal carbon spheres in a ratio of 5 g / 100 mL (5 g microspheres per 100 mL solution), stir in a water bath at 40° C. for 30 min, filter, dry and set aside;

[0127] 3) Colloidal carbon sphere sensitization treatment: the microspheres obtained in step 2) were treated in a 0.1 mol / L stannous chloride aqueous solution at a ratio of 1 g / 20 mL, stirred at 40° C., and filtered;

[0128] 4) Activation treatment of colloidal carbon spheres: the microspheres obtained in step 3) were treated in a ratio of 1 g / 30 mL in a 0.01 mol / L palladium chloride solution, stirred at 45° C., and filtered;

[0129] 5) Colloidal carbon sphere reduction treatment: The microspheres obtained in step 4) are treated in a 0.4 mol / L sodium hypophosphite aqueous solution at a ratio of 1 g / 20 mL, stirred at room temperature, filtered, and dried for later use;

[0130] 6) Preparation of colloidal carbon sphere-metal composite microspheres: The microspheres obtained in step 5) were treated in a mixed solution of metal ions containing 40 g / L nickel sulfate, 50 g / L sodium hypophosphite, 85 g / L potassium sodium tartrate, 40 g / L ammonium sulfate, pH ≈ 9.0 (adjusted by ammonia water) at a ratio of 1 g / 240 mL, stirred in a water bath at 60° C. for 20 min, filtered, and dried for later use;

[0131] 7) The microspheres obtained in step 6) were mixed with sublimed sulfur at a mass ratio of 2.7:1, and then subjected to a sulfurization reaction in an argon atmosphere at a sulfurization temperature of 480° C., a heating rate of 10° C. / min, and a holding time of 3 h to obtain the target product.

[0132] The carbon microsphere core of the metal composite microspheres obtained in this example has a diameter of 5.1 μm, a cavity spacing (the distance between the core and the inner surface of the shell) of 0.19 μm, and the mass percentages of the magnetic metal sulfide shell layer, the magnetic metal shell layer and the carbon microsphere core are 46.9%, 30.5% and 22.6% respectively.

[0133] Example 8

[0134] The preparation of metal composite microspheres with wave absorbing properties, the specific implementation scheme is as follows:

[0135] 1) Preparation of colloidal carbon spheres: 15 g of glucose was dissolved in 150 mL of distilled water and stirred evenly, then 0.4 g of CTAB was added and stirred until all dissolved, and then the mixed solution was transferred to a hydrothermal reactor and reacted at 180° C. for 12 hours, then filtered, washed, and dried to obtain colloidal carbon spheres;

[0136] 2) Surface treatment of colloidal carbon spheres: mix anhydrous ethanol, distilled water, and 3-aminopropyltriethoxysilane in a volume ratio of 30:10:2, add colloidal carbon spheres in a ratio of 5 g / 100 mL (5 g microspheres per 100 mL solution), stir in a water bath at 40° C. for 30 min, filter, dry and set aside;

[0137] 3) Colloidal carbon sphere sensitization treatment: the microspheres obtained in step 2) were treated in a 0.1 mol / L stannous chloride aqueous solution at a ratio of 1 g / 20 mL, stirred at 40° C., and filtered;

[0138] 4) Activation treatment of colloidal carbon spheres: the microspheres obtained in step 3) were treated in a ratio of 1 g / 30 mL in a 0.01 mol / L palladium chloride solution, stirred at 45° C., and filtered;

[0139] 5) Colloidal carbon sphere reduction treatment: The microspheres obtained in step 4) are treated in a 0.4 mol / L sodium hypophosphite aqueous solution at a ratio of 1 g / 20 mL, stirred at room temperature, filtered, and dried for later use;

[0140] 6) Preparation of colloidal carbon sphere-metal composite microspheres: The microspheres obtained in step 5) were treated in a metal ion mixed solution containing 40 g / L nickel sulfate, 50 g / L sodium hypophosphite, 85 g / L potassium sodium tartrate, 40 g / L ammonium sulfate, pH ≈ 9.0 (adjusted by ammonia water) at a ratio of 1 g / 150 mL, stirred in a water bath at 60° C. for 20 min, filtered, and dried for later use;

[0141] 7) The microspheres obtained in step 6) are mixed with sublimed sulfur in a mass ratio of 4:1, and then subjected to a sulfurization reaction in an argon atmosphere at a sulfurization temperature of 450° C., a heating rate of 10° C. / min, and a holding time of 3 h to obtain the target product.

[0142] The carbon microsphere core of the metal composite microspheres obtained in this example has a diameter of 5.1 μm, a cavity spacing (the distance between the core and the inner surface of the shell) of 0.18 μm, and the mass percentages of the magnetic metal sulfide shell layer, the magnetic metal shell layer and the carbon microsphere core are 33.9%, 33.1% and 33% respectively.

[0143] Example 9

[0144] Preparation of metal-metal sulfide hollow microspheres with carbon core, the specific implementation scheme is as follows:

[0145] 1) Preparation of colloidal carbon spheres: 15 g of glucose was dissolved in 150 mL of distilled water and stirred evenly, then 0.4 g of CTAB was added and stirred until all dissolved, and then the mixed solution was transferred to a hydrothermal reactor and reacted at 180° C. for 12 hours, then filtered, washed, and dried to obtain colloidal carbon spheres;

[0146] 2) Surface treatment of colloidal carbon spheres: mix anhydrous ethanol, distilled water, and 3-aminopropyltriethoxysilane in a volume ratio of 30:10:2, add colloidal carbon spheres in a ratio of 5 g / 100 mL (5 g microspheres per 100 mL solution), stir in a water bath at 40° C. for 30 min, filter, dry and set aside;

[0147] 3) Colloidal carbon sphere sensitization treatment: the microspheres obtained in step 2) were treated in a 0.1 mol / L stannous chloride aqueous solution at a ratio of 1 g / 20 mL, stirred at 40° C., and filtered;

[0148] 4) Activation treatment of colloidal carbon spheres: the microspheres obtained in step 3) were treated in a ratio of 1 g / 30 mL in a 0.01 mol / L palladium chloride solution, stirred at 45° C., and filtered;

[0149] 5) Colloidal carbon sphere reduction treatment: The microspheres obtained in step 4) are treated in a 0.4 mol / L sodium hypophosphite aqueous solution at a ratio of 1 g / 20 mL, stirred at room temperature, filtered, and dried for later use;

[0150] 6) Preparation of colloidal carbon sphere-metal composite microspheres: The microspheres obtained in step 5) were treated in a ratio of 1 g / 340 mL in a metal ion mixed solution containing 40 g / L nickel sulfate, 50 g / L sodium hypophosphite, 85 g / L potassium sodium tartrate, 40 g / L ammonium sulfate, pH ≈ 9.0 (adjusted by ammonia water), stirred in a water bath at 60° C. for 20 min, filtered, and dried for later use;

[0151] 7) The microspheres obtained in step 6) were mixed with sublimed sulfur at a mass ratio of 6.1:1, and then subjected to a sulfurization reaction in an argon atmosphere at a sulfurization temperature of 490° C., a heating rate of 10° C. / min, and a holding time of 3 h to obtain the target product.

[0152] The carbon microsphere core of the metal composite microspheres obtained in this example has a diameter of 5.1 μm, a cavity spacing (the distance between the core and the inner surface of the shell) of 0.19 μm, and the mass percentages of the magnetic metal sulfide shell layer, the magnetic metal shell layer and the carbon microsphere core are 22.5%, 58.5% and 19% respectively.

[0153] Comparative Example 1

[0154] The other steps are the same as those in Example 1, except that the carbon intermediate microspheres synthesized by the hydrothermal method are first subjected to heat treatment and then to subsequent treatment. The microspheres do not have volume shrinkage in the final heat treatment and do not generate cavities.

[0155] Comparative Example 2

[0156] The rest is the same as in Example 1, except that no coupling treatment (i.e., step 2) is performed, and the colloidal carbon spheres are surface treated.

[0157] Comparative Example 3

[0158] The other steps are the same as those in Example 1, except that commercial carbon microspheres are used in step 1) instead of carbon intermediate microspheres synthesized by hydrothermal method. The microspheres do not have volume shrinkage and no cavities are generated during the heat treatment.

[0159] Performance Testing:

[0160] The electromagnetic properties of the products prepared in the above embodiments were tested. The test method is: the hollow microspheres prepared in the embodiments are mixed with paraffin, the volume fraction of the hollow microspheres in the obtained mixture is 40%-55%, and coaxial rings are prepared, the inner diameter of the ring is 3mm, the outer diameter is 7mm, and the thickness is 2mm. Then, the electromagnetic parameters are tested by a vector network analyzer to analyze the electromagnetic properties. The results are shown in Table 1.

[0161] Table 1

[0162]

[0163] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A metal composite microsphere with wave absorbing properties, It is characterized in that The structure of the composite microsphere includes the following components arranged in sequence from the inside to the outside: A core selected from carbon microspheres; The shell layer comprises a magnetic metal spherical shell layer and a magnetic metal sulfide spherical shell layer coated on the magnetic metal spherical shell layer; Wherein, the carbon microspheres are located in the cavity formed by the magnetic metal spherical shell layer.

2. The metal composite microsphere according to claim 1, It is characterized in that In the composite microspheres, the content of carbon microspheres is 10-45wt%, the content of magnetic metal spherical shells is 8-65wt%, and the content of magnetic metal sulfide spherical shells is 25-65wt% by weight. Preferably, the magnetic metals in the magnetic metal spherical shell layer and the magnetic metal sulfide spherical shell layer are independently selected from one or more of iron, cobalt and nickel.

3. The metal composite microsphere according to claim 1, It is characterized in that The carbon microspheres are movable in the cavity.

4. The method for preparing the metal composite microspheres according to any one of claims 1 to 3, It is characterized in that The steps include: Colloidal carbon spheres were prepared by hydrothermal method; Pretreating the colloidal carbon spheres; Directed auxiliary assembly of magnetic metal spherical shells on the surface of pretreated colloidal carbon spheres; The colloidal carbon spheres assembled with the magnetic metal spherical shells are subjected to a sulfurization treatment to obtain the metal composite microspheres.

5. The preparation method according to claim 4, It is characterized in that The method for preparing colloidal carbon spheres by hydrothermal method comprises the following steps: The carbon source aqueous solution is mixed with a surfactant, subjected to a hydrothermal reaction, filtered, washed and dried to obtain the intermediate carbon microspheres; Preferably, the carbon source is selected from one or more of glucose, fructose, sucrose, maltose, starch and citric acid; Preferably, the concentration of the carbon source in the carbon source aqueous solution is 0.1-1 mol / L; Preferably, the surfactant is selected from one of cetyltrimethylammonium bromide and polyvinylpyrrolidone; Preferably, the temperature of the hydrothermal reaction is 180-220° C., and the time is 10-15 h.

6. The preparation method according to claim 4, It is characterized in that The pretreatment method comprises the following steps: The colloidal carbon spheres are sequentially subjected to surface coupling treatment, sensitization treatment and activation treatment to obtain; Preferably, the surface coupling treatment is carried out in a surface treatment liquid, wherein the solute of the surface treatment liquid is a coupling agent, and the solvent is anhydrous ethanol and / or distilled water, more preferably a mixture of anhydrous ethanol and distilled water in a volume ratio of 1:1-1:5; Preferably, the temperature of the surface coupling treatment is 20-70°C, more preferably 30-50°C; Preferably, the sensitization treatment is carried out in a sensitizing solution, wherein the sensitizing solution is an aqueous solution of stannous chloride with a concentration of 0.03-0.3 mol / L; Preferably, the activation treatment is carried out in an active solution, wherein the activation solution is a noble metal ion solution with a concentration of 0.002-0.2 mol / L.

7. The preparation method according to claim 4, It is characterized in that The method for directional auxiliary assembly of magnetic metal spherical shells on the surface of pretreated colloidal carbon spheres comprises the following steps: The pretreated colloidal carbon spheres are placed in an auxiliary deposition solution containing magnetic metal ions, stirred in a water bath, filtered, dried, and agglomerates are removed by screening to obtain the colloidal carbon spheres; Preferably, the auxiliary deposition solution comprises a magnetic metal ion source salt, a stabilizer, a reducing agent and a pH adjuster; Preferably, the magnetic metal ion source salt is selected from sulfates, chlorides or organic acid salts of magnetic metals, and the concentration is 10-60 g / L; Preferably, the stabilizer is selected from one or more of ammonium sulfate, potassium sodium tartrate and EDTA, and the concentration is 20-100 g / L; Preferably, the pH adjuster is selected from inorganic bases; Preferably, the pH of the auxiliary deposition solution is 9-11; Preferably, the temperature of the water bath is 50-85°C; Preferably, the addition amount of the pretreated colloidal carbon spheres is 0.0025-0.01 g / mL.

8. The preparation method according to claim 4, It is characterized in that The method of the vulcanization treatment comprises the following steps: The colloidal carbon spheres assembled with magnetic metal spherical shells are mixed with sulfur powder and heat treated in a reducing or inert atmosphere to obtain a product; Preferably, the mass ratio of the colloidal carbon spheres assembled with magnetic metal spherical shells to the sulfur powder is 1.5:1-20:1; Preferably, the heat treatment temperature is 450-550° C. and the time is 2-4 hours.

9. A wave absorbing agent, It is characterized in that The microspheres are prepared from raw materials comprising the metal composite microspheres as described in any one of claims 1 to 3.

10. Use of the metal composite microspheres according to any one of claims 1 to 3 in microwave absorption, catalysis, adsorption or wastewater treatment.

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