Ceramic microbead buoyancy material and preparation process thereof

Abstract

The invention relates to the technical field of ceramic microbeads, in particular to a ceramic microbead buoyancy material and a preparation process thereof.According to the ceramic microbead buoyancy material and the preparation process thereof, a nickel-plated layer is formed on the surface of each ceramic microbead, and spraying and coating treatment is conducted on the surface of each nickel-plated ceramic microbead through strengthening paint; amino groups of the aminated nano cerium oxide hollow microspheres are chelated with nickel atoms on the surfaces of the nickel-plated ceramic microspheres through coordinate bonds, so that stable combination between the coating and the nickel-plated ceramic microspheres is enhanced; in the preparation of the ceramic microbeads, the dispersity of mica powder in ceramic slurry can be improved and a multi-stage pore structure is formed by adding a reinforced compound and carrying out stepped graded heating calcination, so that the interface bonding strength of the reinforced compound in the ceramic microbeads and a ceramic matrix is improved, and the compressive strength of the ceramic microbeads is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic microbeads, and more particularly to a ceramic microbead buoyancy material and a preparation process thereof. Background Art

[0002] Buoyancy materials are low-density, high-strength, low-water-absorption solid materials that provide buoyancy. They play a vital role in ocean development, underwater exploration, and other fields. Currently, commonly used buoyancy materials are primarily composed of a resin matrix and buoyancy fillers.

[0003] As a buoyancy filling material, ceramic microbeads, while possessing excellent chemical stability and water resistance, allowing them to be used in water for long periods without corrosion, are somewhat brittle and prone to cracking when impacted or deformed, which can easily affect their buoyancy performance and overall structural stability. Mica powder possesses excellent elasticity, toughness, and high hardness, but its lamellar structure easily aggregates, making it difficult to evenly disperse the mica powder within the ceramic microbeads. This results in poor interfacial bonding between the mica powder and the ceramic microbeads, and ineffectively improves the compressive strength of the ceramic microbeads. Furthermore, while reducing the density of ceramic microbeads can provide higher buoyancy per unit volume, optimizing their density also requires consideration of their pore structure. While similar-density microbeads may have slightly different porosities, those with higher closed-pore ratios have a stronger ability to block moisture, which is more conducive to ensuring buoyancy stability. Conversely, lower porosity can easily lead to moisture infiltration into the microbeads' internal structure, resulting in a gradual loss of buoyancy.

[0004] Although surface coating of ceramic microbeads can improve the compressive strength of ceramic microbeads and thus enhance their hydrostatic pressure resistance to a certain extent, the surface of ceramic microbeads is relatively smooth, and the active sites on the smooth surface are relatively few, resulting in weaker bonding with organic coatings. This can easily lead to the coating material playing a weak role in the actual application of ceramic microbeads, making it difficult to effectively enhance the compressive strength and unable to guarantee the stability of the hydrostatic pressure resistance of ceramic microbeads in actual applications.

[0005] In addition, during the entire life cycle of the underwater submersible, since it needs to operate back and forth from the sea surface to the maximum water depth many times, the buoyancy material in the underwater submersible will be subjected to the cyclic action of alternating stress in actual application. After a certain number of uses, the ceramic microbeads in the buoyancy material will easily be damaged. As the number of damaged ceramic microbeads increases, the buoyancy material will easily experience local micro-deformation and increased water absorption, which will eventually lead to large-scale failure of the buoyancy material and loss of buoyancy, thereby reducing the safety of the submersible. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the present invention provides a ceramic microbead buoyancy material and a preparation process thereof.

[0007] A ceramic microbead buoyancy material, wherein the ceramic microbeads are nickel-plated to form a nickel-plated layer on the surface, and then a reinforcing coating is atomized and sprayed on the nickel-plated surface of the ceramic microbeads to obtain the ceramic microbead buoyancy material;

[0008] The raw materials of the ceramic microbeads include: 50 to 75 parts by weight of ceramic powder, 1 to 4 parts by weight of a dispersant, 1 to 3 parts by weight of ammonium bicarbonate, 150 to 240 parts by weight of deionized water, 10 to 18 parts by weight of a reinforcing compound and 3 to 7 parts by weight of a binder;

[0009] The raw materials of the reinforced composite include: pretreated mica powder and a tea polyphenol solution with a mass fraction of 5-10%, wherein the amount of the pretreated mica powder is 5-12% of the mass of the tea polyphenol solution, and the pretreated mica powder is obtained by soaking the mica powder in a hydrochloric acid solution;

[0010] The raw materials of the reinforced coating include: 40 to 60 parts by weight of epoxy resin, 5 to 12 parts by weight of amino-treated nano-cerium oxide hollow microspheres, 16 to 30 parts by weight of a curing agent, 4 to 9 parts by weight of a coupling agent and 1 to 3 parts by weight of a leveling agent;

[0011] The nano-cerium oxide hollow microspheres are subjected to amination treatment by using a modification solution containing ethylenediamine, sodium carbonate and deionized water to obtain amination nano-cerium oxide hollow microspheres.

[0012] A preparation process of a ceramic micro-bead buoyancy material comprises the following steps:

[0013] S1: Preparation of a reinforced composite, pre-treating mica powder with a hydrochloric acid solution, adding tea polyphenols to an ethanol solution to prepare a tea polyphenol solution, adding the pre-treated mica powder to the tea polyphenol solution, adjusting the pH to 4-5, heating and stirring the reaction to obtain a reinforced composite;

[0014] S2: Preparation of ceramic microbeads: preparing a ceramic slurry with ceramic powder, dispersant, ammonium bicarbonate, deionized water, reinforcing compound, and binder as raw materials, atomizing the ceramic slurry into droplets, spraying them, drying and forming them to obtain ceramic microbead green bodies, and subjecting the ceramic microbead green bodies to stepwise graded heating and calcining treatments at 200-400°C, 600-800°C, and 1200-1400°C to obtain ceramic microbeads;

[0015] S3: Preparation of nickel-plated ceramic microbeads, wherein the ceramic microbeads are sequentially roughened, sensitized, and activated, and then subjected to chemical nickel plating using a nickel plating solution to obtain nickel-plated ceramic microbeads;

[0016] S4: Preparation of ceramic microbead buoyancy material, performing amination treatment on nano-cerium oxide hollow microspheres, mixing the obtained amination nano-cerium oxide hollow microspheres with epoxy resin, curing agent, coupling agent, and leveling agent to prepare a reinforced coating, and spraying the reinforced coating on the surface of nickel-plated ceramic microbeads to obtain ceramic microbead buoyancy material.

[0017] Furthermore, S1: preparation of the enhanced composite comprises the following steps:

[0018] S1.1: Add mica powder to a 1 mol / L hydrochloric acid solution, stir well, and soak for 1-2 hours. Then, filter under reduced pressure, wash to neutrality, dry, grind, and sieve to obtain pretreated mica powder.

[0019] S1.2: Add tea polyphenols to an ethanol solution to prepare a tea polyphenol solution with a mass fraction of 5-10%, add the pretreated mica powder to the tea polyphenol solution, stir evenly, and adjust the pH of the solution to 4-5 with hydrochloric acid to obtain a mixed solution. Place the mixed solution in a water bath at 75-80°C and continue stirring to react for 3-6 hours. After the reaction is completed, centrifuge and filter to collect the precipitate. The precipitate is dried, ground and sieved to obtain a reinforced composite.

[0020] Furthermore, step S2: preparing ceramic microbeads specifically includes the following steps:

[0021] S2.1: 50-75 parts by weight of ceramic powder, 1-4 parts by weight of dispersant, 1-3 parts by weight of ammonium bicarbonate, and 150-240 parts by weight of deionized water are mixed and ball-milled for 6-12 hours to obtain a primary slurry. 10-18 parts by weight of reinforcing compound and 3-7 parts by weight of binder are added to the primary slurry, stirred and uniformly dispersed, and ultrasonically dispersed for 30-90 minutes to obtain a ceramic slurry.

[0022] S2.2: Using a spray dryer, the ceramic slurry is atomized into droplets of 50 to 200 μm and sprayed out. After the ceramic slurry is spray-dried and formed, a ceramic microbead body is obtained;

[0023] S2.3: Heat and calcine the ceramic microbead body to 200-400°C at a heating rate of 1°C / min, and keep it warm for 1-2 hours. Then, continue heating and calcining at a heating rate of 2-3°C / min to 600-800°C, and keep it warm for 2-3 hours. Subsequently, continue heating and calcining at a heating rate of 5-10°C / min to 1200-1400°C, and keep it warm for 2-4 hours to obtain ceramic microbeads.

[0024] Furthermore, the ceramic powder is composed of one or more of alumina, chlorine oxide, silicon dioxide, and kaolin; the dispersant is at least one of polyvinyl pyrrolidone or ammonium polyacrylate; and the binder is at least one of polyvinyl alcohol, carboxymethyl cellulose, or hydroxypropyl methylcellulose.

[0025] Furthermore, when atomizing and spraying is performed using a spray dryer, the inlet temperature is 150-160°C, the atomizing pressure is 0.3-0.5 MPa, and the outlet temperature is 80-100°C.

[0026] Furthermore, step S4: preparation of ceramic microbead buoyancy material specifically includes the following steps:

[0027] S4.1: Adding nano-cerium oxide hollow microspheres to the modified solution at a solid-liquid mass ratio of (0.1-0.3):1, stirring in a water bath at 60-75°C for 1-3 hours, then centrifuging, filtering under reduced pressure, and drying to obtain amino-modified nano-cerium oxide hollow microspheres;

[0028] S4.2: 40 to 60 parts by weight of epoxy resin, 5 to 12 parts by weight of aminated nano-cerium oxide hollow microspheres, 16 to 30 parts by weight of curing agent, 4 to 9 parts by weight of coupling agent, and 1 to 3 parts by weight of leveling agent are stirred and mixed to obtain a reinforced coating;

[0029] S4.3: Place nickel-plated ceramic microbeads in a fluidized bed, continuously introduce nitrogen into the fluidized bed, and spray the reinforcing coating onto the surface of the nickel-plated ceramic microbeads. After spraying, heat to 40-60°C and dry and cure for 30-60 minutes to obtain a ceramic microbead buoyancy material.

[0030] Furthermore, the modified solution is obtained by mixing ethylenediamine, sodium carbonate and deionized water in a mass ratio of (9-16): (1-5): (30-50).

[0031] Furthermore, the curing agent is at least one of triethylenetetramine, diaminodiphenylmethane, and isophoronediamine; and the coupling agent includes at least one of silane coupling agent KH550, titanate coupling agent, and aluminate coupling agent.

[0032] Furthermore, the preparation steps of nano-cerium oxide hollow microspheres are as follows: after stirring and mixing 6 to 15 parts by weight of cerium nitrate hexahydrate, 50 to 100 parts by weight of deionized water and 90 to 180 parts by weight of ethylene glycol, 5 to 13 parts by weight of glacial acetic acid and 5 to 10 parts by weight of polyvinyl pyrrolidone are sequentially added dropwise under continuous stirring, and stirring is continued for 20 to 40 minutes to obtain a mixed liquid, and then the mixed liquid is transferred to a polytetrafluoroethylene-lined high-pressure reactor, the polytetrafluoroethylene-lined high-pressure reactor is placed in an oven, and the reaction is carried out at 180 to 200° C. for 20 to 24 hours. After the reaction is completed, the mixture is cooled to room temperature, and centrifuged and washed with ethanol and deionized water for 2 to 3 times in sequence, and then vacuum dried and calcined at 450 to 500° C. for 1 to 2 hours to obtain nano-cerium oxide hollow microspheres.

[0033] The present invention has at least the following advantages:

[0034] 1. The present invention uses tea polyphenols and mica powder as raw materials, so that the phenolic hydroxyl groups in the tea polyphenols react with the silanol groups on the surface of the mica to form a reinforced composite. The tea polyphenols in the reinforced composite are beneficial to improving the surface activity of the mica powder, increasing the dispersibility of the mica powder in the ceramic slurry, reducing agglomeration, and making the mica powder more evenly fill the gaps between the ceramic particles, thereby better improving the compressive strength of the ceramic microbeads.

[0035] 2. In the present invention, ceramic microbeads are prepared by step-by-step graded heating and calcining. In the low-temperature calcination stage of 200-400°C, the tea polyphenol component in the reinforcing composite undergoes pyrolysis, foaming and carbonization to form nano-scale closed pores and generate a nano-carbon filling network, which is beneficial to improving the interface bonding strength between the reinforcing composite and the ceramic matrix in the ceramic microbeads, and further improving the compressive strength of the ceramic microbeads; in the medium-temperature calcination stage of 600-800°C, the mica powder component in the reinforcing composite undergoes high-temperature decomposition to form micron-scale pores, thereby preparing ceramic microbeads with a high closed porosity through the formed multi-level pore structure. The high-temperature calcination stage of 1200-1400°C is used to achieve the final sintering and solidification of the ceramic microbeads.

[0036] 3. In the present invention, the ceramic microbeads are subjected to nickel plating treatment to form a nickel plating layer on the surface of the ceramic microbeads, and then the surface of the nickel-plated ceramic microbeads is spray-coated with a reinforcing coating to which aminated nano-cerium oxide hollow microspheres are added. When the aminated nano-cerium oxide hollow microspheres in the reinforcing coating come into contact with the surface of the nickel-plated ceramic microbeads, the amino groups of the aminated nano-cerium oxide hollow microspheres can chelate with the nickel atoms on the surface of the nickel-plated ceramic microbeads through coordination bonds, which is conducive to forming a stable bond between the reinforcing coating and the nickel-plated ceramic microbeads, and then the aminated nano-cerium oxide hollow microspheres are stably attached to the surface of the nickel-plated ceramic microbeads. The obtained buoyancy material formed by the composite of the ceramic microbead buoyancy material and the rubber substrate not only has good hydrostatic pressure resistance and low water absorption, but also can better cope with the cyclic effect of alternating stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a SEM image of the cross-sectional structure of the ceramic microbeads prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] Example 1

[0040] A preparation process of a ceramic micro-bead buoyancy material specifically comprises the following steps:

[0041] S1: Preparation of reinforcement complex,

[0042] S1.1: Add mica powder to a 1 mol / L hydrochloric acid solution, stir well, and soak for 2 hours. Then, filter under reduced pressure, wash to neutrality, dry, grind, and sieve to obtain pretreated mica powder;

[0043] S1.2: Tea polyphenols are added to an ethanol solution to prepare a tea polyphenol solution with a mass fraction of 10%, and pretreated mica powder is added to the tea polyphenol solution in an amount of 12% by mass of the tea polyphenol solution. After stirring evenly, the pH of the solution is adjusted to 4 with hydrochloric acid to obtain a mixed solution. The mixed solution is placed in an 80°C water bath and stirred for 4 hours. After the reaction is completed, the solution is centrifuged and the precipitate is collected by filtration. The precipitate is dried, ground, and sieved to obtain a reinforced composite.

[0044] S2: Preparation of ceramic microbeads,

[0045] S2.1: 70 parts by weight of ceramic powder, 4 parts by weight of polyvinyl pyrrolidone, 3 parts by weight of ammonium bicarbonate, and 240 parts by weight of deionized water were mixed and ball-milled for 12 hours to obtain a primary slurry, wherein the ceramic powder consists of alumina, silica, and kaolin in a mass ratio of 5:1:0.6. 18 parts by weight of a reinforcing compound and 7 parts by weight of polyvinyl alcohol were added to the primary slurry, stirred uniformly, and ultrasonically dispersed for 60 minutes to obtain a ceramic slurry;

[0046] S2.2: The ceramic slurry is atomized into 150 μm droplets using a spray dryer and then sprayed. The inlet temperature of the spray dryer is 150°C, the atomization pressure is 0.5 MPa, and the outlet temperature is 80°C. After the ceramic slurry is spray-dried and formed, a ceramic microbead body is obtained.

[0047] S2.3: The ceramic microbead body was heated and calcined to 330°C at a heating rate of 1°C / min and kept at this temperature for 2 hours. Then, the body was heated and calcined to 780°C at a heating rate of 3°C / min and kept at this temperature for 3 hours. Subsequently, the body was heated and calcined to 1400°C at a heating rate of 10°C / min and kept at this temperature for 4 hours to obtain ceramic microbeads with a density of 0.53 g / cm 3 ;

[0048] S3: Preparation of nickel-plated ceramic microbeads,

[0049] S3.1: After roughening the ceramic microbeads with concentrated sulfuric acid, the roughened ceramic microbeads are sensitized with a sensitizing solution comprising a mixture of a stannous chloride solution and a hydrochloric acid solution. The sensitized ceramic microbeads are activated with an activating solution comprising a dilute hydrochloric acid solution of palladium chloride having a mass fraction of 8%, thereby obtaining pretreated ceramic microbeads.

[0050] S3.2: placing the pretreated ceramic microbeads into a nickel plating solution, stirring for 50 minutes in a water bath at 65°C, and then centrifuging, filtering under reduced pressure, and drying to obtain nickel-plated ceramic microbeads; wherein the nickel plating solution comprises nickel sulfate hexahydrate, sodium hypophosphite, sodium citrate, ammonium sulfate, sodium dodecylbenzenesulfonate, and deionized water; the pH of the nickel plating solution is 8; and the concentrations of nickel sulfate hexahydrate, sodium hypophosphite, sodium citrate, ammonium sulfate, and sodium dodecylbenzenesulfonate in the nickel plating solution are 26 g / L, 23 g / L, 35 g / L, 21 g / L, and 0.05 g / L, respectively;

[0051] S4: Preparation of ceramic microbead buoyancy materials,

[0052] S4.1: Adding the nano-cerium oxide hollow microspheres to a modified solution at a solid-liquid mass ratio of 0.3:1, wherein the modified solution is prepared by mixing ethylenediamine, sodium carbonate, and deionized water in a mass ratio of 9:2:30, and stirring in a 75°C water bath for 3 h. Subsequently, the solution is centrifuged, filtered under reduced pressure, and dried to obtain the amino-modified nano-cerium oxide hollow microspheres.

[0053] S4.2: 56 parts by weight of epoxy resin, 12 parts by weight of aminated nano-cerium oxide hollow microspheres, 30 parts by weight of isophorone diamine, 7 parts by weight of silane coupling agent KH550, and 3 parts by weight of leveling agent BYK-350 were stirred and mixed to obtain a reinforced coating;

[0054] S4.3: Place the nickel-plated ceramic microspheres in a fluidized bed, continuously introduce nitrogen into the fluidized bed, and spray the reinforcing coating onto the surface of the nickel-plated ceramic microspheres at a spraying rate of 1.5 mg / cm 2 After spraying, the mixture was heated to 60°C and dried for 60 minutes to obtain a ceramic micro-bead buoyancy material;

[0055] The preparation steps of nano-cerium oxide hollow microspheres are as follows:

[0056] After 15 parts by weight of cerium nitrate hexahydrate, 100 parts by weight of deionized water and 180 parts by weight of ethylene glycol were stirred and mixed, 13 parts by weight of glacial acetic acid and 10 parts by weight of polyvinyl pyrrolidone were added dropwise in a continuous stirring state, and stirring was continued for 40 minutes to obtain a mixed liquid. Subsequently, the mixed liquid was transferred to a polytetrafluoroethylene-lined high-pressure reactor, and the polytetrafluoroethylene-lined high-pressure reactor was placed in an oven and reacted at 180°C for 24 hours. After the reaction was completed, it was cooled to room temperature, centrifuged and washed three times with ethanol and deionized water in sequence, and then vacuum dried and calcined at 500°C for 2 hours to obtain nano-cerium oxide hollow microspheres.

[0057] Example 2

[0058] A preparation process of a ceramic micro-bead buoyancy material specifically comprises the following steps:

[0059] S1: Preparation of reinforcement complex,

[0060] S1.1: Add mica powder to a 1 mol / L hydrochloric acid solution, stir well, and soak for 1 hour. Then, filter under reduced pressure, wash to neutrality, dry, grind, and sieve to obtain pretreated mica powder;

[0061] S1.2: Tea polyphenols are added to an ethanol solution to prepare a tea polyphenol solution with a mass fraction of 10%, and pretreated mica powder is added to the tea polyphenol solution in an amount of 12% by mass of the tea polyphenol solution. After stirring evenly, the pH of the solution is adjusted to 4 with hydrochloric acid to obtain a mixed solution. The mixed solution is placed in a 75°C water bath and stirred for 6 hours. After the reaction is completed, the solution is centrifuged and the precipitate is collected by filtration. The precipitate is dried, ground, and sieved to obtain a reinforced composite.

[0062] S2: Preparation of ceramic microbeads,

[0063] S2.1: 70 parts by weight of ceramic powder, 4 parts by weight of polyvinyl pyrrolidone, 3 parts by weight of ammonium bicarbonate, and 240 parts by weight of deionized water were mixed and ball-milled for 6 hours to obtain a primary slurry, wherein the ceramic powder consists of alumina, silica, and kaolin in a mass ratio of 5:1:0.6. 18 parts by weight of a reinforcing compound and 7 parts by weight of polyvinyl alcohol were added to the primary slurry, stirred uniformly, and ultrasonically dispersed for 30 minutes to obtain a ceramic slurry;

[0064] S2.2: The ceramic slurry is atomized into 150 μm droplets using a spray dryer and then sprayed. The inlet temperature of the spray dryer is 150°C, the atomization pressure is 0.5 MPa, and the outlet temperature is 80°C. After the ceramic slurry is spray-dried and formed, a ceramic microbead body is obtained.

[0065] S2.3: The ceramic microbead body was heated and calcined to 400°C at a heating rate of 1°C / min and kept at this temperature for 2 hours. Then, the body was heated and calcined to 800°C at a heating rate of 2°C / min and kept at this temperature for 3 hours. Subsequently, the body was heated and calcined to 1400°C at a heating rate of 10°C / min and kept at this temperature for 4 hours to obtain ceramic microbeads with a density of 0.55 g / cm 3 ;

[0066] S3: Preparation of nickel-plated ceramic microbeads,

[0067] S3.1: After roughening the ceramic microbeads with concentrated sulfuric acid, the roughened ceramic microbeads are sensitized with a sensitizing solution comprising a mixture of a stannous chloride solution and a hydrochloric acid solution. The sensitized ceramic microbeads are activated with an activating solution comprising a dilute hydrochloric acid solution of palladium chloride having a mass fraction of 8%, thereby obtaining pretreated ceramic microbeads.

[0068] S3.2: placing the pretreated ceramic microbeads into a nickel plating solution, stirring for 50 minutes in a water bath at 65°C, and then centrifuging, filtering under reduced pressure, and drying to obtain nickel-plated ceramic microbeads; wherein the nickel plating solution comprises nickel sulfate hexahydrate, sodium hypophosphite, sodium citrate, ammonium sulfate, sodium dodecylbenzenesulfonate, and deionized water; the pH of the nickel plating solution is 8; and the concentrations of nickel sulfate hexahydrate, sodium hypophosphite, sodium citrate, ammonium sulfate, and sodium dodecylbenzenesulfonate in the nickel plating solution are 26 g / L, 23 g / L, 35 g / L, 21 g / L, and 0.05 g / L, respectively;

[0069] S4: Preparation of ceramic microbead buoyancy materials,

[0070] S4.1: Adding the nano-cerium oxide hollow microspheres to a modified solution with a solid-liquid mass ratio of 0.3:1, wherein the modified solution is prepared by mixing ethylenediamine, sodium carbonate, and deionized water in a mass ratio of 9:2:30, and stirring in a 60°C water bath for 2 h. Subsequently, the solution is centrifuged, filtered under reduced pressure, and dried to obtain the amino-modified nano-cerium oxide hollow microspheres;

[0071] S4.2: 56 parts by weight of epoxy resin, 12 parts by weight of aminated nano-cerium oxide hollow microspheres, 30 parts by weight of isophorone diamine, 7 parts by weight of silane coupling agent KH550, and 3 parts by weight of leveling agent BYK-350 were stirred and mixed to obtain a reinforced coating;

[0072] S4.3: Place the nickel-plated ceramic microspheres in a fluidized bed, continuously introduce nitrogen into the fluidized bed, and spray the reinforcing coating onto the surface of the nickel-plated ceramic microspheres at a spraying rate of 1.5 mg / cm 2 After spraying, the mixture was heated to 60°C and dried for 30 minutes to obtain a ceramic micro-bead buoyancy material;

[0073] The preparation steps of nano-cerium oxide hollow microspheres are as follows:

[0074] After 15 parts by weight of cerium nitrate hexahydrate, 100 parts by weight of deionized water and 180 parts by weight of ethylene glycol were stirred and mixed, 13 parts by weight of glacial acetic acid and 10 parts by weight of polyvinyl pyrrolidone were added dropwise in a continuous stirring state, and stirring was continued for 40 minutes to obtain a mixed liquid. Subsequently, the mixed liquid was transferred to a polytetrafluoroethylene-lined high-pressure reactor, and the polytetrafluoroethylene-lined high-pressure reactor was placed in an oven and reacted at 180°C for 24 hours. After the reaction was completed, it was cooled to room temperature, centrifuged and washed three times with ethanol and deionized water in sequence, and then vacuum dried and calcined at 500°C for 2 hours to obtain nano-cerium oxide hollow microspheres.

[0075] Example 3

[0076] A preparation process of a ceramic micro-bead buoyancy material specifically comprises the following steps:

[0077] S1: Preparation of reinforcement complex,

[0078] S1.1: Add mica powder to a 1 mol / L hydrochloric acid solution, stir well, and soak for 2 hours. Then, filter under reduced pressure, wash to neutrality, dry, grind, and sieve to obtain pretreated mica powder;

[0079] S1.2: Tea polyphenols are added to an ethanol solution to prepare a tea polyphenol solution with a mass fraction of 8%. Pretreated mica powder is added to the tea polyphenol solution in an amount of 8% by mass of the tea polyphenol solution. After stirring evenly, the pH of the solution is adjusted to 5 with hydrochloric acid to obtain a mixed solution. The mixed solution is placed in an 80°C water bath and stirred for 4 hours. After the reaction is completed, the solution is centrifuged and the precipitate is collected by filtration. The precipitate is dried, ground, and sieved to obtain a reinforced composite.

[0080] S2: Preparation of ceramic microbeads,

[0081] S2.1: 50 parts by weight of ceramic powder, 2 parts by weight of polyvinyl pyrrolidone, 1 part by weight of ammonium bicarbonate, and 180 parts by weight of deionized water were mixed and ball-milled for 12 hours to obtain a primary slurry, wherein the ceramic powder consists of alumina, silica, and kaolin in a mass ratio of 5:1:0.6. 10 parts by weight of a reinforcing compound and 4 parts by weight of polyvinyl alcohol were added to the primary slurry, stirred uniformly, and ultrasonically dispersed for 60 minutes to obtain a ceramic slurry;

[0082] S2.2: The ceramic slurry is atomized into 150 μm droplets using a spray dryer and then sprayed. The inlet temperature of the spray dryer is 150°C, the atomization pressure is 0.5 MPa, and the outlet temperature is 80°C. After the ceramic slurry is spray-dried and formed, a ceramic microbead body is obtained.

[0083] S2.3: The ceramic microbead body was heated and calcined to 330°C at a heating rate of 1°C / min and kept at this temperature for 2 hours. Then, the body was heated and calcined to 780°C at a heating rate of 3°C / min and kept at this temperature for 3 hours. Subsequently, the body was heated and calcined to 1400°C at a heating rate of 10°C / min and kept at this temperature for 4 hours to obtain ceramic microbeads with a density of 0.56 g / cm 3 ;

[0084] S3: Preparation of nickel-plated ceramic microbeads,

[0085] S3.1: After roughening the ceramic microbeads with concentrated sulfuric acid, the roughened ceramic microbeads are sensitized with a sensitizing solution comprising a mixture of a stannous chloride solution and a hydrochloric acid solution. The sensitized ceramic microbeads are activated with an activating solution comprising a dilute hydrochloric acid solution of palladium chloride having a mass fraction of 8%, thereby obtaining pretreated ceramic microbeads.

[0086] S3.2: placing the pretreated ceramic microbeads into a nickel plating solution, stirring for 50 minutes in a water bath at 65°C, and then centrifuging, filtering under reduced pressure, and drying to obtain nickel-plated ceramic microbeads; wherein the nickel plating solution comprises nickel sulfate hexahydrate, sodium hypophosphite, sodium citrate, ammonium sulfate, sodium dodecylbenzenesulfonate, and deionized water; the pH of the nickel plating solution is 8; and the concentrations of nickel sulfate hexahydrate, sodium hypophosphite, sodium citrate, ammonium sulfate, and sodium dodecylbenzenesulfonate in the nickel plating solution are 26 g / L, 23 g / L, 35 g / L, 21 g / L, and 0.05 g / L, respectively;

[0087] S4: Preparation of ceramic microbead buoyancy materials,

[0088] S4.1: Adding the nano-cerium oxide hollow microspheres to a modified solution at a solid-liquid mass ratio of 0.1:1, wherein the modified solution is prepared by mixing ethylenediamine, sodium carbonate, and deionized water in a mass ratio of 9:2:30, and stirring in a 75°C water bath for 3 h. Subsequently, the solution is centrifuged, filtered under reduced pressure, and dried to obtain the amino-modified nano-cerium oxide hollow microspheres.

[0089] S4.2: 56 parts by weight of epoxy resin, 5 parts by weight of aminated nano-cerium oxide hollow microspheres, 30 parts by weight of isophorone diamine, 7 parts by weight of silane coupling agent KH550, and 3 parts by weight of leveling agent BYK-350 were stirred and mixed to obtain a reinforced coating;

[0090] S4.3: Place the nickel-plated ceramic microspheres in a fluidized bed, continuously introduce nitrogen into the fluidized bed, and spray the reinforcing coating onto the surface of the nickel-plated ceramic microspheres at a spraying rate of 1.5 mg / cm 2 After spraying, the mixture was heated to 60°C and dried for 60 minutes to obtain a ceramic micro-bead buoyancy material;

[0091] The preparation steps of nano-cerium oxide hollow microspheres are as follows:

[0092] After 8 parts by weight of cerium nitrate hexahydrate, 70 parts by weight of deionized water and 120 parts by weight of ethylene glycol were stirred and mixed, 6 parts by weight of glacial acetic acid and 6 parts by weight of polyvinyl pyrrolidone were sequentially added dropwise under continuous stirring, and stirring was continued for 40 minutes to obtain a mixed liquid. Subsequently, the mixed liquid was transferred to a polytetrafluoroethylene-lined high-pressure reactor, and the polytetrafluoroethylene-lined high-pressure reactor was placed in an oven and reacted at 180°C for 24 hours. After the reaction was completed, it was cooled to room temperature, centrifuged and washed three times with ethanol and deionized water in sequence, and then vacuum dried and calcined at 500°C for 2 hours to obtain nano-cerium oxide hollow microspheres.

[0093] Comparative Example 1

[0094] Compared with Example 1, the difference of Comparative Example 1 is that step S1 is removed, the reinforcing compound in step S2.1 is replaced with mica powder of equal weight, and the other steps and ingredients remain unchanged to prepare ceramic microbeads, which is recorded as Comparative Example 1.

[0095] Comparative Example 2

[0096] Compared with Example 1, the difference of Comparative Example 2 is that step S2.3 is removed, and the ceramic microbead body obtained in step S2.2 is heated to 1400°C at a heating rate of 10°C / min and calcined, and kept warm for 4 hours. The remaining steps and components remain unchanged to prepare ceramic microbeads, which is recorded as Comparative Example 2.

[0097] Comparative Example 3

[0098] Compared with Example 1, the difference of Comparative Example 3 is that step S2.3 is removed, and the ceramic microbead body obtained in step S2.2 is heated and calcined to 780°C at a heating rate of 3°C / min and kept warm for 3 hours. Subsequently, it is heated and calcined to 1400°C at a heating rate of 10°C / min and kept warm for 4 hours. The remaining steps and components remain unchanged to prepare ceramic microbeads, which is recorded as Comparative Example 3.

[0099] Comparative Example 4

[0100] Compared with Example 1, the difference of Comparative Example 4 is that step S2.3 is removed, and the ceramic microbead body obtained in step S2.2 is heated and calcined to 330°C at a heating rate of 1°C / min and kept warm for 2 hours. Subsequently, it is heated and calcined to 1400°C at a heating rate of 10°C / min and kept warm for 4 hours. The remaining steps and components remain unchanged to prepare ceramic microbeads, which is recorded as Comparative Example 4.

[0101] Table 1 is a comparison of the physical properties of ceramic microbeads of Examples 1-3 and Comparative Examples 1-4:

[0102] Table 1:

[0103] Group <![CDATA[Density (g / cm 3 )]]> Porosity (%) Closed cell rate (%) Compressive strength (MPa) Example 1 0.53 85.4 80.9 22.8 Example 2 0.55 85.1 81.2 23.2 Example 3 0.56 84.8 80.5 22.5 Comparative Example 1 0.53 85.2 62.7 18.6 Comparative Example 2 0.75 72.5 39.6 16.4 Comparative Example 3 0.61 80.6 45.1 13.7 Comparative Example 4 0.64 79.2 56.8 15.5

[0104] As shown in Table 1, although the density and porosity of the ceramic microbeads in Examples 1-3 are similar to those in Comparative Example 1, the closed porosity and compressive strength of the ceramic microbeads in Examples 1-3 are better than those in Comparative Example 1, indicating that the addition of the reinforcing composite improves the closed porosity and compressive strength of the ceramic microbeads compared to the direct addition of mica powder, thereby obtaining ceramic microbeads with higher closed porosity and better compressive strength. Compared with the ceramic microbeads in Comparative Examples 2-4, the ceramic microbeads in Examples 1-3 have lower density and higher porosity, and the closed porosity and compressive strength of the ceramic microbeads in Examples 1-3 are better than those in Comparative Examples 2-4. In addition, Figure 1As shown in FIG. 1 , the cross-sectional structure of the ceramic microbeads in Example 1 is dense and composed of a multi-level closed-pore structure. This indicates that the use of stepped graded heating and calcining for sintering can form a multi-level closed-pore structure within the ceramic microbeads, increase the closed-porosity of the ceramic microbeads, and contribute to improving the compressive strength of the ceramic microbeads.

[0105] Comparative Example 5

[0106] Compared with Example 1, the difference of Comparative Example 5 is that step S3 is removed, the nickel-plated ceramic microbeads in step S4.3 are replaced with ceramic microbeads, and the other steps and components remain unchanged to prepare a ceramic microbead buoyancy material, which is recorded as Comparative Example 5.

[0107] Comparative Example 6

[0108] Compared with Example 1, the difference of Comparative Example 6 is that step S4.1 is removed, and the amino-treated nano-cerium oxide hollow microspheres in step S4.2 are replaced with nano-cerium oxide hollow microspheres. The other steps and components remain unchanged to prepare a ceramic microbead buoyancy material, which is recorded as Comparative Example 6.

[0109] The ceramic microbead buoyancy materials in Examples 1-3 and Comparative Examples 5-6 were mixed with epoxy resin (the mixing mass ratio of the ceramic microbead buoyancy material to the epoxy resin was 1:1), cured and formed to obtain composite buoyancy materials of equal volume. The hydrostatic pressure resistance and water absorption rate of each group of composite buoyancy materials were tested according to ISO21173:2019. Subsequently, 5 samples were taken from each group of composite buoyancy materials prepared. The hydrostatic pressure of deep-sea working conditions was simulated using a deep-sea seawater pressure testing machine, and the test samples were subjected to alternating pressure cycle tests. Each alternating pressure cycle included 12 hours of high-pressure hydrostatic pressure of 20 MPa and 12 hours of normal pressure of 0.1 MPa, and the test was repeated 10 times. After the pressure cycle test, the hydrostatic pressure resistance and water absorption rate of each group of samples were tested and the average value was taken. The results are shown in Table 2.

[0110] Table 2:

[0111]

[0112] As can be seen in Table 2, the hydrostatic pressure resistance and waterproof performance of the composite buoyancy materials in Examples 1-3 are superior to those in Comparative Examples 5-6. Furthermore, after the alternating pressure cycle test, the changes in the hydrostatic pressure resistance and water absorption of the composite buoyancy materials in Examples 1-3 are relatively small, indicating that the composite buoyancy materials can effectively maintain good hydrostatic pressure resistance and waterproof and anti-permeability properties. This indicates that by nickel-plating the surface of ceramic microbeads and then spraying a strengthening coating on them to prepare a composite buoyancy material from the resulting ceramic microbead buoyancy material, the hydrostatic pressure resistance and waterproof performance of the composite buoyancy material can be effectively improved, enabling the composite buoyancy material to better cope with the cyclic effects of alternating pressure.

[0113] It should be understood that those skilled in the art may make improvements or modifications based on the above description, and all such improvements and modifications shall fall within the scope of protection of the appended claims. Any portion of this specification not described in detail is prior art known to those skilled in the art.

Claims

1. A ceramic microbead buoyancy material, characterized in that: The ceramic microbeads are nickel plated to form a nickel layer on the surface, and then atomized and sprayed with a strengthening coating on the surface of the nickel-plated ceramic microbeads to obtain a ceramic microbead buoyancy material; The raw materials of the ceramic microbeads include: 50 to 75 parts by weight of ceramic powder, 1 to 4 parts by weight of a dispersant, 1 to 3 parts by weight of ammonium bicarbonate, 150 to 240 parts by weight of deionized water, 10 to 18 parts by weight of a reinforcing compound and 3 to 7 parts by weight of a binder; The raw materials of the reinforced composite include: pretreated mica powder and a tea polyphenol solution with a mass fraction of 5-10%, wherein the amount of the pretreated mica powder is 5-12% of the mass of the tea polyphenol solution, and the pretreated mica powder is obtained by soaking the mica powder in a hydrochloric acid solution; The raw materials of the reinforced coating include: 40 to 60 parts by weight of epoxy resin, 5 to 12 parts by weight of amino-treated nano-cerium oxide hollow microspheres, 16 to 30 parts by weight of a curing agent, 4 to 9 parts by weight of a coupling agent and 1 to 3 parts by weight of a leveling agent; The nano-cerium oxide hollow microspheres are subjected to amination treatment by using a modification solution containing ethylenediamine, sodium carbonate and deionized water to obtain amination nano-cerium oxide hollow microspheres.

2. The preparation process of the ceramic microbead buoyancy material according to claim 1, characterized in that: The steps include: S1: Preparation of a reinforced composite, pre-treating mica powder with a hydrochloric acid solution, adding tea polyphenols to an ethanol solution to prepare a tea polyphenol solution, adding the pre-treated mica powder to the tea polyphenol solution, adjusting the pH to 4-5, heating and stirring the reaction to obtain a reinforced composite; S2: Preparation of ceramic microbeads: preparing a ceramic slurry with ceramic powder, dispersant, ammonium bicarbonate, deionized water, reinforcing compound, and binder as raw materials, atomizing the ceramic slurry into droplets, spraying them, drying and forming them to obtain ceramic microbead green bodies, and subjecting the ceramic microbead green bodies to stepwise graded heating and calcining treatments at 200-400°C, 600-800°C, and 1200-1400°C to obtain ceramic microbeads; S3: Preparation of nickel-plated ceramic microbeads, wherein the ceramic microbeads are sequentially roughened, sensitized, and activated, and then subjected to chemical nickel plating using a nickel plating solution to obtain nickel-plated ceramic microbeads; S4: Preparation of ceramic microbead buoyancy material, performing amination treatment on nano-cerium oxide hollow microspheres, mixing the obtained amination nano-cerium oxide hollow microspheres with epoxy resin, curing agent, coupling agent, and leveling agent to prepare a reinforced coating, and spraying the reinforced coating on the surface of nickel-plated ceramic microbeads to obtain ceramic microbead buoyancy material.

3. The preparation process of the ceramic microbead buoyancy material according to claim 2, characterized in that: S1: Preparation of the reinforcement composite, specifically comprising the following steps: S1.1: Add mica powder to a 1 mol / L hydrochloric acid solution, stir well, and soak for 1-2 hours. Then, filter under reduced pressure, wash to neutrality, dry, grind, and sieve to obtain pretreated mica powder. S1.2: Add tea polyphenols to an ethanol solution to prepare a tea polyphenol solution with a mass fraction of 5-10%, add the pretreated mica powder to the tea polyphenol solution, stir evenly, and adjust the pH of the solution to 4-5 with hydrochloric acid to obtain a mixed solution. Place the mixed solution in a water bath at 75-80°C and continue stirring to react for 3-6 hours. After the reaction is completed, centrifuge and filter to collect the precipitate. The precipitate is dried, ground and sieved to obtain a reinforced composite.

4. The preparation process of the ceramic microbead buoyancy material according to claim 3, characterized in that: Step S2: Preparation of ceramic microbeads, specifically including the following steps: S2.1: 50-75 parts by weight of ceramic powder, 1-4 parts by weight of dispersant, 1-3 parts by weight of ammonium bicarbonate, and 150-240 parts by weight of deionized water are mixed and ball-milled for 6-12 hours to obtain a primary slurry. 10-18 parts by weight of reinforcing compound and 3-7 parts by weight of binder are added to the primary slurry, stirred and uniformly dispersed, and ultrasonically dispersed for 30-90 minutes to obtain a ceramic slurry. S2.2: Using a spray dryer, the ceramic slurry is atomized into droplets of 50 to 200 μm and sprayed out. After the ceramic slurry is spray-dried and formed, a ceramic microbead body is obtained; S2.3: Heat and calcine the ceramic microbead body to 200-400°C at a heating rate of 1°C / min, and keep it warm for 1-2 hours. Then, continue heating and calcining at a heating rate of 2-3°C / min to 600-800°C, and keep it warm for 2-3 hours. Subsequently, continue heating and calcining at a heating rate of 5-10°C / min to 1200-1400°C, and keep it warm for 2-4 hours to obtain ceramic microbeads.

5. The preparation process of the ceramic microbead buoyancy material according to claim 4, characterized in that: The ceramic powder is composed of one or more of alumina, chlorine oxide, silicon dioxide, and kaolin; the dispersant is at least one of polyvinyl pyrrolidone and ammonium polyacrylate; and the binder is at least one of polyvinyl alcohol, carboxymethyl cellulose, and hydroxypropyl methylcellulose.

6. The preparation process of the ceramic microbead buoyancy material according to claim 5, characterized in that: When atomizing and spraying is performed using a spray dryer, the inlet temperature is 150-160°C, the atomizing pressure is 0.3-0.5 MPa, and the outlet temperature is 80-100°C.

7. The preparation process of the ceramic microbead buoyancy material according to claim 2, characterized in that: Step S4: Preparation of ceramic microbead buoyancy material, specifically comprising the following steps: S4.1: Adding nano-cerium oxide hollow microspheres to the modified solution at a solid-liquid mass ratio of (0.1-0.3):1, stirring in a water bath at 60-75°C for 1-3 hours, then centrifuging, filtering under reduced pressure, and drying to obtain amino-modified nano-cerium oxide hollow microspheres; S4.2: Stir and mix 40 to 60 parts by weight of epoxy resin, 5 to 12 parts by weight of amino-treated nano-cerium oxide hollow microspheres, 16 to 30 parts by weight of curing agent, 4 to 9 parts by weight of coupling agent and 1 to 3 parts by weight of leveling agent to obtain a reinforced coating; S4.3: Place nickel-plated ceramic microbeads in a fluidized bed, continuously introduce nitrogen into the fluidized bed, and atomize and spray the reinforced coating onto the surface of the nickel-plated ceramic microbeads. After spraying, heat to 40 to 60°C and dry and cure for 30 to 60 minutes to obtain a ceramic microbead buoyancy material.

8. The process for preparing the ceramic microbead buoyancy material according to claim 7, wherein: The modified solution is obtained by mixing ethylenediamine, sodium carbonate and deionized water in a mass ratio of (9-16): (1-5): (30-50).

9. The process for preparing the ceramic microbead buoyancy material according to claim 7, wherein: The curing agent is at least one of triethylenetetramine, diaminodiphenylmethane and isophoronediamine; the coupling agent includes at least one of silane coupling agent KH550, titanate coupling agent and aluminate coupling agent.

10. The process for preparing the ceramic microbead buoyancy material according to claim 9, characterized in that: The preparation steps of nano-cerium oxide hollow microspheres are as follows: after stirring and mixing 6-15 parts by weight of cerium nitrate hexahydrate, 50-100 parts by weight of deionized water and 90-180 parts by weight of ethylene glycol, 5-13 parts by weight of glacial acetic acid and 5-10 parts by weight of polyvinyl pyrrolidone are sequentially added dropwise under continuous stirring, and stirring is continued for 20-40 minutes to obtain a mixed liquid, and then the mixed liquid is transferred into a polytetrafluoroethylene-lined high-pressure reactor, the polytetrafluoroethylene-lined high-pressure reactor is placed in an oven, and the reaction is carried out at 180-200° C. for 20-24 hours. After the reaction is completed, the mixture is cooled to room temperature, and centrifugally washed with ethanol and deionized water for 2-3 times in sequence, and vacuum dried and calcined at 450-500° C. for 1-2 hours to obtain nano-cerium oxide hollow microspheres.

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