Lightweight explosion-proof ceramic sleeve and preparation method thereof

Abstract

The present application relates to the technical field of explosion-proof ceramic material, and discloses a light-weight explosion-proof ceramic sleeve and a preparation method thereof.The light-weight explosion-proof ceramic sleeve ceramic comprises a base layer and a composite protective layer, and the composite protective layer is coated on the surface of the base layer.The base layer takes alumina and clay as main raw materials, and through the synergistic effect of pore-forming agent and glass fiber, the volume density of the ceramic sleeve is reduced, and the thermal shock resistance is significantly improved.The composite protective layer takes alicyclic epoxy resin and polyurethane modified acrylate as main raw materials, and various functional additives are added to endow the ceramic sleeve with excellent impact resistance and anti-burst capacity.The light-weight and explosion-proof performance are unified through the internal and external synergistic design of the base layer and the protective layer.

Description

Technical Field

[0001] This invention relates to the field of explosion-proof ceramic materials technology, specifically to a lightweight explosion-proof ceramic sleeve and its preparation method. Background Technology

[0002] Alumina ceramics are widely used as packaging shells for electronic components, high-temperature insulation parts, and protective structural materials due to their high strength, high hardness, excellent wear resistance, good chemical stability, and high-temperature resistance. However, the inherent brittleness and low toughness of alumina ceramics severely limit their reliability in harsh conditions such as impact resistance and explosion-proof applications. Especially in environments with rapid temperature changes, the thermal stress generated inside the ceramic material can easily trigger the propagation of microcracks, leading to catastrophic material failure.

[0003] To overcome the aforementioned problems, researchers have attempted to prepare porous alumina ceramics by introducing pore-forming agents to reduce bulk density and buffer thermal stress. However, while porous structures improve thermal shock resistance, they often come at the cost of a significant decrease in mechanical strength. Furthermore, introducing fiber-reinforcing phases into the ceramic matrix is ​​an effective way to improve the material's toughness. However, the large difference in thermal expansion coefficients and poor chemical compatibility between reinforcing phases, such as glass fibers, and the alumina matrix leads to weak interfacial bonding. Under impact, cracks easily initiate and propagate at the interface, weakening the toughening effect of the fibers. Therefore, how to simultaneously improve the thermal shock resistance and impact / explosion protection capabilities of alumina ceramics while maintaining their lightweight properties has become a pressing technical challenge in this field. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a lightweight explosion-proof ceramic sleeve and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A lightweight explosion-proof ceramic sleeve, wherein the ceramic comprises a base layer and a composite protective layer, and the composite protective layer is coated on the surface of the base layer;

[0007] The matrix layer comprises the following raw materials in parts by weight: 40-60 parts alumina powder, 8-15 parts pore-forming agent, 5-15 parts clay, 3-8 parts modified glass fiber, 2-5 parts zirconium oxide, and 1-3 parts barium sulfate.

[0008] Furthermore, the pore-forming agent is one of cellulose, lignin, or polyethylene glycol;

[0009] The modified glass fiber is prepared by the following steps:

[0010] Step A1: Disperse high-silica glass fibers in acetone by ultrasonication for 30 min, wash and dry them, then stir them in acid solution for 12 h, wash and dry them, and collect the acidified glass fibers; disperse the acidified glass fibers by ultrasonication in a mixture of ethanol and deionized water, heat the mixture to 60-70℃, then slowly add KH570, reflux for 12-24 h, filter, wash and dry them to obtain double bond modified glass fibers;

[0011] Further, in step A1, the ratio of high silica glass fiber to acid solution is 1g:15-25mL, and the volume ratio of concentrated sulfuric acid to hydrogen peroxide in the acid solution is 6-8:2-4.

[0012] Furthermore, in step A1, the ratio of acidified glass fiber, ethanol, deionized water, and KH570 is 1g:45mL:5mL:0.5-1.5mL;

[0013] Step A2: Add double bond modified glass fiber to toluene and ultrasonically disperse for 30 min, then add acrylic acid and azobisisobutyronitrile in sequence and stir until homogeneous. Purge with nitrogen gas and heat to 80℃ for 5-6 h. Filter, wash and dry to obtain carboxylated glass fiber.

[0014] Furthermore, in step A2, the ratio of double-bond modified glass fiber, toluene, acrylic acid, and azobisisobutyronitrile is 1g:100mL:0.02-0.05mol:0.01-0.02g;

[0015] Step A3: Disperse carboxylated glass fibers evenly in deionized water by ultrasonication to form a mixture; add boric acid to anhydrous ethanol and stir to dissolve, then transfer to a 65°C water bath and add the mixture dropwise while stirring. The addition is completed within 30 minutes. Then continue stirring to dry the mixture, and then vacuum dry it overnight at 70°C to obtain the glass fiber@boric acid precursor.

[0016] Furthermore, in step A3, the ratio of carboxylated glass fiber, deionized water, boric acid, and anhydrous ethanol is 1g:10mL:1-3g:15mL.

[0017] Step A4: Mix glass fiber@boric acid precursor and aluminum powder and add to a ball mill jar with a ball-to-material ratio of 20:1. Then, argon gas is introduced and the mixture is placed in a variable speed planetary ball mill. First, it is ball milled at 200 rpm / min for 2 hours, and then at 400 rpm / min for 2 hours. After standing for 24 hours, the composite powder is collected, cold-pressed, and then transferred to a tube furnace. High-purity argon gas is introduced and the mixture is heated to the sintering temperature. The temperature is then held for 1-2 hours, cooled to room temperature, polished, hot-extruded, and cooled to room temperature to obtain modified glass fiber.

[0018] Further, the cold pressing in step A4 specifically involves: loading the composite powder into a cold pressing mold and holding it under a pressure of 300-400MPa for 2-3 minutes to form a cylinder with a diameter of 20mm;

[0019] Furthermore, the sintering temperature in step A4 is 570-580℃, and the heating rate is 5℃ / min;

[0020] Furthermore, the polishing described in step A4 specifically involves polishing the surface with sandpaper until it is shiny;

[0021] Further, the hot extrusion described in step A4 specifically involves: placing the polished material into a hot extrusion mold, then placing it in a box-type resistance furnace, holding it at 500°C for 20-30 minutes, and then quickly transferring it to an extruder for extrusion at a pressure of 500 MPa with an extrusion ratio of 16:1.

[0022] The composite protective layer comprises the following raw materials in parts by weight: 25-35 parts alicyclic epoxy resin, 15-25 parts polyurethane modified acrylate, 5-10 parts silicon carbide micro powder, 3-6 parts carboxyl-terminated butadiene-acrylonitrile rubber, 1-2 parts silane coupling agent, 8-12 parts curing agent, 2-3 parts curing accelerator, 2-4 parts initiator, 0.2-0.5 parts defoamer, and 0.3-0.5 parts leveling agent;

[0023] Furthermore, the curing agent is any one of acid anhydride curing agents;

[0024] Furthermore, the curing accelerator is any one of the tertiary amines;

[0025] Furthermore, the initiator is either photoinitiator 1173 or photoinitiator 184;

[0026] Furthermore, the defoamer is BYK-052N, and the leveling agent is BYK-310;

[0027] Furthermore, the silane coupling agent is one of KH550 or KH560.

[0028] A method for preparing a lightweight explosion-proof ceramic sleeve includes the following steps:

[0029] Step S1: Weigh the raw materials according to the weight parts, add alumina powder, clay, zirconium oxide, barium sulfate, modified glass fiber and pore-forming agent into a mixer and stir evenly, then transfer to a grinder for grinding, then transfer to a mold, put into a vacuum calcination furnace, and calcinate at 950-1050℃ for 6-8 hours, and cool to room temperature with the furnace to obtain the matrix layer.

[0030] Step S2: Weigh the raw materials according to the weight parts, stir the alicyclic epoxy resin and polyurethane modified acrylate at 300-500 rpm / min for 5-10 min, add the carboxyl-terminated butadiene nitrile rubber and silane coupling agent and continue stirring for 10-15 min, then add silicon carbide micro powder, defoamer and leveling agent and stir at 800-1000 rpm / min for 20-30 min, then add acid anhydride curing agent, tertiary amine accelerator and initiator and stir for 5-10 min to obtain the composite protective coating;

[0031] Step S3: Sandblast the surface of the substrate layer to control the roughness Ra at 3-6μm to remove surface dust; then spray the composite protective coating onto the surface of the substrate layer to control the thickness at 100-300μm. After spraying, let it stand for 15-30 minutes to allow the coating to level. Then irradiate the coated substrate layer under 365nm ultraviolet light for 1-2 minutes to pre-shape it. Finally, transfer it to an oven for heat curing and cool it to room temperature to obtain a lightweight explosion-proof ceramic sleeve.

[0032] Furthermore, the thermosetting process described in step S3 is divided into two stages: the first stage has a curing temperature of 80-100℃ and a curing time of 1-2 hours; the second stage has a curing temperature of 150-180℃ and a curing time of 2-4 hours.

[0033] The beneficial effects of this invention are:

[0034] The lightweight explosion-proof ceramic sleeve prepared by this invention consists of an alumina-based porous ceramic matrix layer and a composite protective layer. Through a synergistic design of the inner and outer layers, it achieves a balance between lightweight design and explosion-proof performance. In the matrix layer, a pore-forming agent and modified glass fiber work synergistically. The microporous structure formed by the pore-forming agent reduces the material density and buffers thermal stress, while the modified glass fiber provides reinforcement and toughening through a strong interfacial bond. Together, they enhance the thermal shock resistance of the matrix. The outer composite protective layer utilizes the viscoelastic energy absorption properties of epoxy resin and the high hardness and impact resistance of silicon carbide micropowder to provide reliable impact resistance and explosion-proof protection for the ceramic sleeve. The complementary functions of the two layers give this ceramic sleeve a comprehensive advantage in terms of lightweight, thermal shock resistance, and explosion-proof performance.

[0035] The modified glass fiber introduced into the matrix layer fundamentally solves the core problem of poor compatibility between the fiber and the ceramic matrix due to the mismatch of physical properties, thus significantly improving the explosion-proof performance of the material. First, carboxyl groups are introduced onto the fiber surface. Then, through hydrogen bonding between the surface carboxyl groups and boric acid, and subsequent in-situ reactions, an alumina shell with the same chemical composition as the matrix is ​​coated onto the glass fiber surface. This shell integrates with the alumina matrix during sintering, forming a smooth transition from the fiber body (SiO2) to the outer layer (Al2O3), eliminating interfacial stress concentration caused by differences in thermal expansion coefficients, and achieving a seamless and strong chemical bond between the fiber and the matrix. When the ceramic sleeve is impacted, this strong interfacial bond ensures that the fiber effectively exerts its toughening effect—the fiber, like a microscopic steel bar, spans both ends of the crack, bearing tensile loads through its high strength, and consuming a large amount of crack propagation energy through mechanisms such as fiber pull-out, crack deflection, and bridging, significantly hindering rapid crack penetration and thus delaying overall material failure. Meanwhile, the externally coated composite protective layer acts as a flexible barrier, absorbing impact energy through the viscoelastic deformation of epoxy resin and resisting external impacts through high-hardness silicon carbide micropowder. The synergistic effect of the inner and outer layers enables the ceramic sleeve to resist the initiation and propagation of cracks from the inside and to buffer and disperse the impact force from the outside when subjected to impact, thus ultimately giving it excellent impact resistance and crack prevention capabilities. Detailed Implementation

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] The glass fibers used in the following embodiments are all high-silica glass fibers;

[0038] Example 1: Modified glass fiber was prepared by the following steps:

[0039] Step A1: Disperse 1g of high-silica glass fiber in 50mL of acetone by ultrasonication for 30min, wash with water and dry, then place it in 15mL of acid solution and stir for 12h, wash, dry and collect the acidified glass fiber; disperse 1g of acidified glass fiber in a mixture of 45mL of ethanol and 5mL of deionized water by ultrasonication, heat to 60℃, then slowly add 0.5mL of KH570, reflux for 12h, filter, wash and dry to obtain double bond modified glass fiber, and the volume ratio of concentrated sulfuric acid to hydrogen peroxide in the acid solution is 6:4;

[0040] Step A2: Add 1g of double bond modified glass fiber to 100mL of toluene and ultrasonically disperse for 30min. Then, add 0.02mol of acrylic acid and 0.01g of azobisisobutyronitrile in sequence and stir well. Purge with nitrogen gas and heat to 80℃ for 5h. Filter, wash and dry to obtain carboxylated glass fiber.

[0041] Step A3: Disperse 1g of carboxylated glass fiber evenly in 10mL of deionized water by ultrasonication to form a mixture; add 1g of boric acid to 15mL of anhydrous ethanol and stir to dissolve, then transfer to a 65℃ water bath and add the mixture dropwise while stirring. The addition is completed within 30min. Then continue stirring and drying in a dry state, and then vacuum dry at 70℃ overnight to obtain the glass fiber@boric acid precursor.

[0042] Step A4: After mixing glass fiber@boric acid precursor and aluminum powder, add it to a ball mill jar with a ball-to-material ratio of 20:1. Then, argon gas is introduced, and the mixture is placed in a variable speed planetary ball mill. First, it is ball milled at 200 rpm / min for 2 hours, and then at 400 rpm / min for 2 hours. After standing for 24 hours, the composite powder is collected, cold-pressed, and then transferred to a tube furnace. High-purity argon gas is introduced, and the mixture is heated to the sintering temperature. The temperature is then held for 1 hour, cooled to room temperature, polished, hot-extruded, and cooled to room temperature to obtain modified glass fiber.

[0043] Preferably, the cold pressing in step A4 specifically involves: loading the composite powder into a cold pressing mold and holding it under a pressure of 300 MPa for 2 minutes to form a cylinder with a diameter of 20 mm;

[0044] Preferably, the sintering temperature in step A4 is 570°C, and the heating rate is 5°C / min;

[0045] Preferably, the polishing in step A4 specifically involves polishing the surface with sandpaper until it is shiny;

[0046] Preferably, the hot extrusion in step A4 specifically involves: placing the polished material into a hot extrusion mold, then placing it in a box-type resistance furnace, holding it at 500°C for 20 minutes, and then quickly transferring it to an extruder for extrusion at a pressure of 500 MPa with an extrusion ratio of 16:1.

[0047] Example 2: Modified glass fiber was prepared by the following steps:

[0048] Step A1: Disperse 1g of high-silica glass fiber in 50mL of acetone by ultrasonication for 30min, wash with water and dry, then place it in 20mL of acid solution and stir for 12h, wash, dry and collect the acidified glass fiber; disperse 1g of acidified glass fiber in a mixture of 45mL of ethanol and 5mL of deionized water by ultrasonication, heat to 65℃, then slowly add 1mL of KH570, reflux for 18h, filter, wash and dry to obtain double bond modified glass fiber, and the volume ratio of concentrated sulfuric acid to hydrogen peroxide in the acid solution is 7:3;

[0049] Step A2: Add 1g of double bond modified glass fiber to 100mL of toluene and ultrasonically disperse for 30min. Then, add 0.035mol of acrylic acid and 0.015g of azobisisobutyronitrile in sequence and stir well. Purge with nitrogen gas and heat to 80℃ for 5.5h. Filter, wash and dry to obtain carboxylated glass fiber.

[0050] Step A3: Disperse 1g of carboxylated glass fiber evenly in 10mL of deionized water by ultrasonication to form a mixture; add 2g of boric acid to 15mL of anhydrous ethanol and stir to dissolve, then transfer to a 65℃ water bath and add the mixture dropwise while stirring. The addition is completed within 30min. Then continue stirring and drying in a dry state, and then vacuum dry at 70℃ overnight to obtain the glass fiber@boric acid precursor.

[0051] Step A4: Mix glass fiber@boric acid precursor and aluminum powder and add to a ball mill jar with a ball-to-material ratio of 20:1. Then, argon gas is introduced and the mixture is placed in a variable speed planetary ball mill. First, it is ball milled at 200 rpm / min for 2 hours, and then at 400 rpm / min for 2 hours. After standing for 24 hours, the composite powder is collected, cold-pressed, and then transferred to a tube furnace. High-purity argon gas is introduced and the mixture is heated to the sintering temperature. The temperature is then held for 1.5 hours, cooled to room temperature, polished, hot-extruded, and cooled to room temperature to obtain modified glass fiber.

[0052] Preferably, the cold pressing in step A4 specifically involves: loading the composite powder into a cold pressing mold and holding it under a pressure of 350 MPa for 2.5 minutes to form a cylinder with a diameter of 20 mm;

[0053] Preferably, the sintering temperature in step A4 is 580°C, and the heating rate is 5°C / min;

[0054] Preferably, the polishing in step A4 specifically involves polishing the surface with sandpaper until it is shiny;

[0055] Preferably, the hot extrusion in step A4 specifically involves: placing the polished material into a hot extrusion mold, then placing it in a box-type resistance furnace, holding it at 500°C for 25 minutes, and then quickly transferring it to an extruder for extrusion at a pressure of 500 MPa with an extrusion ratio of 16:1.

[0056] Example 3: Modified glass fiber was prepared by the following steps:

[0057] Step A1: Disperse 1g of high-silica glass fiber in 50mL of acetone by ultrasonication for 30min, wash and dry it, then place it in 25mL of acid solution and stir for 12h. Wash, dry and collect the acidified glass fiber. Disperse 1g of acidified glass fiber in a mixture of 45mL of ethanol and 5mL of deionized water by ultrasonication and heat to 70℃. Then slowly add 1.5mL of KH570 and reflux for 24h. Filter, wash and dry to obtain double bond modified glass fiber. The volume ratio of concentrated sulfuric acid to hydrogen peroxide in the acid solution is 8:2.

[0058] Step A2: Add 1g of double bond modified glass fiber to 100mL of toluene and ultrasonically disperse for 30min. Then, add 0.05mol of acrylic acid and 0.02g of azobisisobutyronitrile in sequence and stir well. Purge with nitrogen gas and heat to 80℃ for 6h. Filter, wash and dry to obtain carboxylated glass fiber.

[0059] Step A3: Disperse 1g of carboxylated glass fiber evenly in 10mL of deionized water by ultrasonication to form a mixture; add 3g of boric acid to 15mL of anhydrous ethanol and stir to dissolve, then transfer to a 65℃ water bath and add the mixture dropwise while stirring. The addition is completed within 30min. Then continue stirring and drying in a dry state, and then vacuum dry at 70℃ overnight to obtain the glass fiber@boric acid precursor.

[0060] Step A4: After mixing glass fiber@boric acid precursor and aluminum powder, add it to a ball mill jar with a ball-to-material ratio of 20:1. Then, argon gas is introduced, and the mixture is placed in a variable speed planetary ball mill. First, it is ball milled at a speed of 200 rpm / min for 2 hours, and then at a speed of 400 rpm / min for 2 hours. After standing for 24 hours, the composite powder is collected, cold-pressed, and then transferred to a tube furnace. High-purity argon gas is introduced, and the mixture is heated to the sintering temperature. The temperature is then held for 2 hours, cooled to room temperature, polished, hot-extruded, and cooled to room temperature to obtain modified glass fiber.

[0061] Preferably, the cold pressing in step A4 specifically involves: loading the composite powder into a cold pressing mold and holding it under a pressure of 400 MPa for 3 minutes to form a cylinder with a diameter of 20 mm;

[0062] Preferably, the sintering temperature in step A4 is 580°C, and the heating rate is 5°C / min;

[0063] Preferably, the polishing in step A4 specifically involves polishing the surface with sandpaper until it is shiny;

[0064] Preferably, the hot extrusion in step A4 specifically involves: placing the polished material into a hot extrusion mold, then placing it in a box-type resistance furnace, holding it at 500°C for 30 minutes, and then quickly transferring it to an extruder for extrusion at a pressure of 500 MPa with an extrusion ratio of 16:1.

[0065] Example 4: A method for preparing a lightweight explosion-proof ceramic sleeve includes the following steps:

[0066] The matrix layer comprises the following raw materials in parts by weight: 40 parts alumina powder, 8 parts pore-forming agent, 5 parts clay, 3 parts modified glass fiber prepared in Example 1, 2 parts zirconium oxide, and 1 part barium sulfate.

[0067] Preferably, the pore-forming agent is cellulose;

[0068] The composite protective layer comprises the following raw materials in parts by weight: 25 parts alicyclic epoxy resin, 15 parts polyurethane modified acrylate, 5 parts silicon carbide micro powder, 3 parts carboxyl-terminated butadiene-acrylonitrile rubber, 1 part silane coupling agent, 8 parts curing agent, 2 parts curing accelerator, 2 parts initiator, 0.2 parts defoamer, and 0.3 parts leveling agent.

[0069] Preferably, the curing agent is methylhexahydrophthalic anhydride;

[0070] Preferably, the curing accelerator is triethanolamine;

[0071] Preferably, the initiator is photoinitiator 1173;

[0072] Preferably, the defoamer is BYK-052N and the leveling agent is BYK-310;

[0073] Preferably, the silane coupling agent is KH550;

[0074] Step S1: Weigh the raw materials according to the weight parts, add alumina powder, clay, zirconium oxide, barium sulfate, modified glass fiber prepared in Example 1 and pore-forming agent into a mixer and stir evenly, then transfer to a grinder for grinding, then transfer to a mold, put into a vacuum calcination furnace, calcinate at 950°C for 8 hours, and cool to room temperature with the furnace to obtain the matrix layer.

[0075] Step S2: Weigh the raw materials according to the weight parts, stir the alicyclic epoxy resin and polyurethane modified acrylate at 300 rpm / min for 5 min, add the carboxyl-terminated butadiene nitrile rubber and silane coupling agent and continue stirring for 10 min, then add silicon carbide micro powder, defoamer and leveling agent and stir at 800 rpm / min for 20 min, then add acid anhydride curing agent, tertiary amine accelerator and initiator and stir for 5 min to obtain the composite protective coating;

[0076] Step S3: Sandblast the surface of the substrate layer to control the roughness Ra at 3μm to remove surface dust; then spray the composite protective coating onto the surface of the substrate layer to control the thickness at 100μm. After spraying, let it stand for 15 minutes to allow the coating to level. Then irradiate the coated substrate layer under 365nm ultraviolet light for 1 minute to pre-shape it. Then transfer it to an oven for heat curing and cool it to room temperature to obtain a lightweight explosion-proof ceramic sleeve.

[0077] Preferably, the thermosetting process in step S3 is divided into two stages: the first stage has a curing temperature of 80°C and a curing time of 1 hour; the second stage has a curing temperature of 150°C and a curing time of 2 hours.

[0078] Example 5: A method for preparing a lightweight explosion-proof ceramic sleeve includes the following steps:

[0079] The matrix layer comprises the following raw materials in parts by weight: 50 parts alumina powder, 12 parts pore-forming agent, 10 parts clay, 5 parts modified glass fiber prepared in Example 2, 3.5 parts zirconium oxide, and 2 parts barium sulfate.

[0080] Preferably, the pore-forming agent is lignin;

[0081] The composite protective layer comprises the following raw materials in parts by weight: 30 parts alicyclic epoxy resin, 20 parts polyurethane modified acrylate, 7.5 parts silicon carbide micro powder, 4.5 parts carboxyl-terminated butadiene-acrylonitrile rubber, 1.5 parts silane coupling agent, 10 parts curing agent, 2.5 parts curing accelerator, 3 parts initiator, 0.4 parts defoamer, and 0.4 parts leveling agent;

[0082] Preferably, the curing agent is methylhexahydrophthalic anhydride;

[0083] Preferably, the curing accelerator is triethanolamine;

[0084] Preferably, the initiator is photoinitiator 184;

[0085] Preferably, the defoamer is BYK-052N and the leveling agent is BYK-310;

[0086] Preferably, the silane coupling agent is KH560;

[0087] Step S1: Weigh the raw materials according to the weight parts, add alumina powder, clay, zirconium oxide, barium sulfate, modified glass fiber prepared in Example 2 and pore-forming agent into a mixer and stir evenly, then transfer to a grinder for grinding, then transfer to a mold, put into a vacuum calcination furnace, calcinate at 1000°C for 6 hours, and cool to room temperature with the furnace to obtain the matrix layer.

[0088] Step S2: Weigh the raw materials according to the weight parts, stir the alicyclic epoxy resin and polyurethane modified acrylate at 400 rpm / min for 8 min, add the carboxyl-terminated butadiene nitrile rubber and silane coupling agent and continue stirring for 12 min, then add silicon carbide micro powder, defoamer and leveling agent and stir at 900 rpm / min for 25 min, then add acid anhydride curing agent, tertiary amine accelerator and initiator and stir for 7.5 min to obtain the composite protective coating;

[0089] Step S3: Sandblast the surface of the substrate layer, control the roughness Ra to 4μm, remove the surface for 25 minutes to allow the coating to level, then irradiate the coated substrate layer under 365nm ultraviolet light for 1.5 minutes to pre-shape, then transfer it to an oven for heat curing, and cool it to room temperature to obtain a lightweight explosion-proof ceramic sleeve.

[0090] Preferably, the thermosetting process in step S3 is divided into two stages: the first stage has a curing temperature of 90°C and a curing time of 1.5 hours; the second stage has a curing temperature of 170°C and a curing time of 3 hours.

[0091] Example 6: A method for preparing a lightweight explosion-proof ceramic sleeve includes the following steps:

[0092] The matrix layer comprises the following raw materials in parts by weight: 60 parts alumina powder, 15 parts pore-forming agent, 15 parts clay, 8 parts modified glass fiber prepared in Example 3, 5 parts zirconium oxide, and 3 parts barium sulfate.

[0093] Preferably, the pore-forming agent is polyethylene glycol;

[0094] The composite protective layer comprises the following raw materials in parts by weight: 35 parts alicyclic epoxy resin, 25 parts polyurethane modified acrylate, 10 parts silicon carbide micro powder, 6 parts carboxyl-terminated butadiene-acrylonitrile rubber, 2 parts silane coupling agent, 12 parts curing agent, 3 parts curing accelerator, 4 parts initiator, 0.5 parts defoamer, and 0.5 parts leveling agent.

[0095] Preferably, the curing agent is methylhexahydrophthalic anhydride;

[0096] Preferably, the curing accelerator is triethanolamine;

[0097] Preferably, the initiator is photoinitiator 1173;

[0098] Preferably, the defoamer is BYK-052N and the leveling agent is BYK-310;

[0099] Preferably, the silane coupling agent is KH560;

[0100] Step S1: Weigh the raw materials according to the weight parts, add alumina powder, clay, zirconium oxide, barium sulfate, modified glass fiber prepared in Example 3 and pore-forming agent into a mixer and stir evenly, then transfer to a grinder for grinding, then transfer to a mold, put into a vacuum calcination furnace, calcinate at 1050°C for 7 hours, and cool to room temperature with the furnace to obtain the matrix layer.

[0101] Step S2: Weigh the raw materials according to the weight parts, stir the alicyclic epoxy resin and polyurethane modified acrylate at 500 rpm / min for 10 min, add the carboxyl-terminated butadiene nitrile rubber and silane coupling agent and continue stirring for 15 min, then add silicon carbide micro powder, defoamer and leveling agent and stir at 1000 rpm / min for 30 min, then add acid anhydride curing agent, tertiary amine accelerator and initiator and stir for 10 min to obtain the composite protective coating;

[0102] Step S3: Sandblast the surface of the substrate layer to control the roughness Ra at 6μm to remove surface dust; then spray the composite protective coating onto the surface of the substrate layer to control the thickness at 300μm. After spraying, let it stand for 30 minutes to allow the coating to level. Then irradiate the coated substrate layer under 365nm ultraviolet light for 2 minutes to pre-shape it. Then transfer it to an oven for heat curing and cool it to room temperature to obtain a lightweight explosion-proof ceramic sleeve.

[0103] Preferably, the thermosetting process in step S3 is divided into two stages: the first stage has a curing temperature of 100°C and a curing time of 1 hour; the second stage has a curing temperature of 180°C and a curing time of 4 hours.

[0104] Comparative Example 1: This comparative example is a ceramic sleeve, which differs from Example 6 in that it is a ceramic sleeve made only of the substrate layer and is not coated with a composite protective layer, but otherwise it is the same.

[0105] Comparative Example 2: This comparative example is a ceramic sleeve, which differs from Example 6 in that glass fiber is used instead of the glass fiber prepared in Example 3, and all other aspects are the same.

[0106] The ceramic sleeves prepared in Examples 4-6 and Comparative Examples 1-2 were subjected to performance tests:

[0107] Bulk density performance: The bulk density of the matrix layer was tested according to GB / T 25995-2010;

[0108] Thermal shock resistance: Refer to GB / T 37246-2018 to test the substrate layer. Heat the sample to a set temperature of 500℃, hold it at that temperature, and then quickly quench it in cold water. Observe whether cracks appear on the surface of the sample.

[0109] Adhesion performance test: The adhesion level of the composite protective layer to the substrate layer is tested in accordance with GB / T 9286-2021 "Cross-cut test for paints and varnishes"; Impact resistance test: Using a drop hammer impact tester, the sample is placed on the platform and a 60g drop hammer is used to drop the sample to a new position, starting from a height of 5cm. If no crack is found, the height is increased by 5cm each time until a visible crack appears on the sample. The height value is recorded.

[0110] The test results are shown in Table 1:

[0111] Table 1: Performance Test Results

[0112]

[0113] As can be seen from Table 1, the ceramic sleeve prepared by the present invention has lightweight, impact-resistant, explosion-proof and thermal shock resistant properties, and the composite protective layer has excellent adhesion. Therefore, the ceramic sleeve has good application prospects in electronic component packaging shells, high-temperature heat insulation components and protective structural materials.

[0114] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the scope defined by the inventive concept, they should all fall within the protection scope of the present invention.

Claims

1. A lightweight explosion-proof ceramic sleeve, characterized in that, The ceramic comprises a substrate layer and a composite protective layer, wherein the composite protective layer is coated on the surface of the substrate layer; The matrix layer comprises the following raw materials in parts by weight: 40-60 parts alumina powder, 8-15 parts pore-forming agent, 5-15 parts clay, 3-8 parts modified glass fiber, 2-5 parts zirconium oxide, and 1-3 parts barium sulfate. The composite protective layer comprises the following raw materials in parts by weight: 25-35 parts alicyclic epoxy resin, 15-25 parts polyurethane modified acrylate, 5-10 parts silicon carbide micro powder, 3-6 parts carboxyl-terminated butadiene-acrylonitrile rubber, 1-2 parts silane coupling agent, 8-12 parts curing agent, 2-3 parts curing accelerator, 2-4 parts initiator, 0.2-0.5 parts defoamer, and 0.3-0.5 parts leveling agent.

2. The lightweight explosion-proof ceramic sleeve according to claim 1, characterized in that, The pore-forming agent is one of cellulose, lignin, or polyethylene glycol.

3. The lightweight explosion-proof ceramic sleeve according to claim 1, characterized in that, The modified glass fiber is prepared by the following steps: Step A1: Disperse high-silica glass fibers in acetone by ultrasonication for 30 min, wash and dry them, then stir them in acid solution for 12 h, wash and dry them, and collect the acidified glass fibers; disperse the acidified glass fibers by ultrasonication in a mixture of ethanol and deionized water, heat the mixture to 60-70℃, then slowly add KH570, reflux for 12-24 h, filter, wash and dry them to obtain double bond modified glass fibers; Step A2: Add double bond modified glass fiber to toluene and ultrasonically disperse for 30 min, then add acrylic acid and azobisisobutyronitrile in sequence and stir until homogeneous. Purge with nitrogen gas and heat to 80℃ for 5-6 h. Filter, wash and dry to obtain carboxylated glass fiber. Step A3: Disperse carboxylated glass fibers evenly in deionized water by ultrasonication to form a mixture; add boric acid to anhydrous ethanol and stir to dissolve, then transfer to a 65°C water bath and add the mixture dropwise while stirring. The addition is completed within 30 minutes. Then continue stirring to dry the mixture, and then vacuum dry it overnight at 70°C to obtain the glass fiber@boric acid precursor. Step A4: Mix glass fiber@boric acid precursor and aluminum powder and add to a ball mill jar with a ball-to-material ratio of 20:

1. Then, introduce argon gas and place the mixture in a variable speed planetary ball mill. First, ball mill at 200 rpm / min for 2 hours, then at 400 rpm / min for 2 hours. Let it stand for 24 hours, collect the composite powder, cold press it, and then transfer it to a tube furnace. Introduce high-purity argon gas, heat it to the sintering temperature, hold it at that temperature for 1-2 hours, cool it to room temperature, grind it, hot extrude it, and cool it to room temperature to obtain modified glass fiber.

4. The lightweight explosion-proof ceramic sleeve according to claim 3, characterized in that, In step A1, the ratio of high silica glass fiber to acid solution is 1g:15-25mL, and the volume ratio of concentrated sulfuric acid to hydrogen peroxide in the acid solution is 6-8:2-4. The ratio of acidified glass fiber, ethanol, deionized water and KH570 is 1g:45mL:5mL:0.5-1.5mL.

5. A lightweight explosion-proof ceramic sleeve according to claim 3, characterized in that, In step A2, the ratio of double-bond modified glass fiber, toluene, acrylic acid, and azobisisobutyronitrile is 1g:100mL:0.02-0.05mol:0.01-0.02g.

6. A lightweight explosion-proof ceramic sleeve according to claim 3, characterized in that, In step A3, the ratio of carboxylated glass fiber, deionized water, boric acid, and anhydrous ethanol is 1g:10mL:1-3g:15mL.

7. A lightweight explosion-proof ceramic sleeve according to claim 3, characterized in that, The cold pressing in step A4 specifically involves: loading the composite powder into a cold pressing mold and maintaining it under a pressure of 300-400MPa for 2-3 minutes to form a cylinder with a diameter of 20mm; the sintering temperature is 570-580℃ and the heating rate is 5℃ / min.

8. A lightweight explosion-proof ceramic sleeve according to claim 3, characterized in that, The hot extrusion described in step A4 is as follows: the polished material is placed in a hot extrusion mold, then placed in a box-type resistance furnace, and kept at 500°C for 20-30 minutes. After that, it is quickly transferred to an extruder and extruded at a pressure of 500MPa with an extrusion ratio of 16:

1.

9. A lightweight explosion-proof ceramic sleeve according to claim 1, characterized in that, The curing agent is any one of the acid anhydride curing agents, the curing accelerator is any one of the tertiary amines, the initiator is any one of photoinitiator 1173 or photoinitiator 184, the defoamer is BYK-052N, the leveling agent is BYK-310, and the silane coupling agent is any one of KH550 or KH560.

10. A method for preparing a lightweight explosion-proof ceramic sleeve according to any one of claims 1-9, characterized in that, Includes the following steps: Step S1: Weigh the raw materials according to the weight parts, add alumina powder, clay, zirconium oxide, barium sulfate, modified glass fiber and pore-forming agent into a mixer and stir evenly, then transfer to a grinder for grinding, then transfer to a mold, put into a vacuum calcination furnace, and calcinate at 950-1050℃ for 6-8 hours, and cool to room temperature with the furnace to obtain the matrix layer. Step S2: Weigh the raw materials according to the weight parts, stir the alicyclic epoxy resin and polyurethane modified acrylate at 300-500 rpm / min for 5-10 min, add the carboxyl-terminated butadiene nitrile rubber and silane coupling agent and continue stirring for 10-15 min, then add silicon carbide micro powder, defoamer and leveling agent and stir at 800-1000 rpm / min for 20-30 min, then add acid anhydride curing agent, tertiary amine accelerator and initiator and stir for 5-10 min to obtain the composite protective coating; Step S3: Sandblast the surface of the substrate layer to control the roughness Ra at 3-6μm to remove surface dust; then spray the composite protective coating onto the substrate layer surface to control the thickness at 100-300μm. After spraying, let it stand for 15-30 minutes to allow the coating to level. Then, irradiate the coated substrate layer under 365nm ultraviolet light for 1-2 minutes to pre-shape it. Then, transfer it to an oven for heat curing and cool it to room temperature to obtain a lightweight explosion-proof ceramic sleeve. The heat curing is divided into two stages: the first stage has a curing temperature of 80-100℃ and a curing time of 1-2 hours; the second stage has a curing temperature of 150-180℃ and a curing time of 2-4 hours.

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