Magnetic composite clay as well as preparation method and application thereof

Abstract

The invention discloses magnetic composite clay as well as a preparation method and application thereof, belongs to the technical field of clay processing, and is used for solving the technical problem that high temperature resistance and magnetism of clay in the prior art need to be further improved. The heat-resistant silicon resin comprises the following raw materials in parts by weight: 10-12 parts of modified nano ferroferric oxide, 60-70 parts of kaolin, 2-4 parts of a modified adhesive, 11-15 parts of hydromica and 8-11 parts of quartz sand, the modified nano ferroferric oxide with a hollow structure is prepared by a solvothermal method, and the heat-resistant silicon resin containing a titanium source is prepared by a sol-gel method. Inorganic filler is further added into heat-resistant silicon resin to obtain a modified adhesive, the modified nano ferroferric oxide is used for providing magnetism, the modified adhesive is used as a cross-linking agent, kaolin, hydromica and quartz sand are used as base materials, and the composite clay with magnetism is obtained, so that the magnetism of the composite clay is improved; the high temperature resistance and the mechanical property of the composite clay are also improved.

Description

Technical Field

[0001] The present invention relates to the technical field of clay processing, and particularly relates to a magnetic composite clay, a preparation method thereof, and an application thereof. Background Art

[0002] As a natural mineral, clay is widely used in traditional industries such as ceramics and construction due to its excellent plasticity, fire resistance, and chemical stability. However, with the development of modern technology, single clay materials are gradually unable to meet the needs of high-end applications. The demands of modern life for materials not only focus on basic physical properties but also involve aspects such as functionality, environmental adaptability, and sustainability.

[0003] Among them, magnetic modification of clay materials is a current research hotspot. Adding ferrite, magnetite, neodymium iron boron, etc. to clay can not only retain the original advantages of clay but also endow it with new functions such as magnetic responsiveness, magnetic heating, and electromagnetic shielding. The application potential of magnetically modified clay is huge, especially in fields such as smart home, magnetic heating, and environmental sensing. For example, making a teapot with magnetic heating function from magnetic clay. After the teapot has magnetism, the heating process is more efficient and uniform, and by controlling the external magnetic field, the precipitation of calcium and magnesium ions in water can be inhibited, reducing the formation of water scale and making the water quality softer and sweeter.

[0004] However, clay is composed of multiple minerals, has high viscosity and a porous structure, and its original physical properties do not have strong magnetism. When performing magnetic modification, magnetic materials such as ferrite, magnetite, and neodymium iron boron are usually added to enhance magnetism. However, due to the low density of clay and the limited binding degree between its structure and magnetic materials, the magnetic materials cannot fully exert their due magnetization ability. Adding adhesives during the preparation of magnetic clay. Under high-temperature conditions, traditional organic adhesives will not only lose their bonding effect but may even cause the release of harmful gases, affecting the health and environmental friendliness of the materials;

[0005] In addition, the high-temperature tolerance of adhesives is poor, which easily leads to a decrease in the mechanical strength of the composite material, and even deformation or cracking occurs during long-term high-temperature applications, further reducing its performance stability. This poses great challenges to the research and production of some high-temperature applications. Summary of the Invention

[0006] The purpose of the present invention is to provide a magnetic composite clay, a preparation method thereof, and an application thereof, which are used to solve the technical problems that the high-temperature resistance and magnetism of clay in the prior art need to be further improved.

[0007] The object of the present invention can be achieved by the following technical solutions: A magnetic composite clay, comprising the following raw materials by weight: 10-12 parts of modified nano-ferroferric oxide, 60-70 parts of kaolin, 2-4 parts of modified binder, 11-15 parts of hydromica, and 8-11 parts of quartz sand.

[0008] The modified nano-ferroferric oxide is prepared by the following steps:

[0009] A1. Put ferric chloride hexahydrate, sodium citrate and ethylene glycol into a reaction kettle, stir for 1-5 min, add sodium acetate solution, heat up to 190-200 °C, keep the temperature for reaction for 12-15 h, and perform post-treatment to obtain crude nano-ferroferric oxide;

[0010] The reaction principle for the preparation of crude nano-ferroferric oxide is:

[0011] During the reaction process, ethylene glycol forms a microenvironment similar to a "soft template" at high temperature. The entanglement of its molecular chains and the micelle structure provide a growth confinement space for ferroferric oxide. Sodium citrate complexes with Fe3+ through carboxyl groups, inhibits excessive growth of particles and regulates the formation of crystal nuclei, and finally forms a hollow structure. Sodium acetate, as a base source, adjusts the pH of the solution to weakly alkaline, promotes the hydrolysis and crystallization process of Fe3+. In the later stage of the reaction, small particles dissolve and large particles continue to grow to form a hollow structure, obtaining crude nano-ferroferric oxide;

[0012] A2. Put the crude nano-ferroferric oxide, deionized water, ethanol, γ-glycidoxypropyltrimethoxysilane and ball-milling medium into a planetary ball mill, ball-mill for 2-4 h, and perform post-treatment to obtain modified nano-ferroferric oxide.

[0013] The reaction principle for the preparation of modified nano-ferroferric oxide is:

[0014] During the ball-milling process, more hydroxyl groups are exposed on the surface of the crude nano-ferroferric oxide, which can undergo a condensation reaction with the silanol groups generated by the hydrolysis of γ-glycidoxypropyltrimethoxysilane to obtain modified nano-ferroferric oxide modified with a silane coupling agent.

[0015] Further, the sodium acetate solution is composed of sodium acetate and ethylene glycol in a dosage ratio of 0.5 - 1 g : 20 - 25 mL, and the dosage ratio of ferric chloride hexahydrate, sodium citrate, ethylene glycol, and sodium acetate solution is 2 - 5 g : 0.05 - 0.1 g : 30 - 40 mL : 15 - 20 mL. The post-treatment steps include: after the reaction is completed, wait for the reaction solution to cool to room temperature, perform suction filtration, wash the filter cake with deionized water and ethanol 1 - 2 times, transfer it to a drying oven at a temperature of 50 - 60 °C, and dry to constant weight to obtain the crude nano-ferroferric oxide. In step A2, the ball milling medium is composed of zirconia with a diameter of 9 mm and zirconia with a diameter of 14 mm in a mass ratio of 4 : 1, and the dosage ratio of the crude nano-ferroferric oxide, deionized water, ethanol, γ-glycidoxypropyltrimethoxysilane, and ball milling medium is 10 - 15 g : 8 - 10 mL : 100 - 150 mL : 4 - 6 g : 100 - 150 g. The post-treatment steps include: after the reaction is completed, wash the product with ethanol 1 - 2 times, transfer it to an oven at a temperature of 55 - 65 °C, dry to constant weight, and pass through a 200-mesh sieve to obtain the modified nano-ferroferric oxide.

[0016] Further, the preparation method of the modified adhesive is as follows: place the modified heat-resistant silicone resin and isopropanol in a reaction kettle, heat up to 30 - 40 °C, keep warm and stir for 5 - 10 min, add aluminum powder, boron carbide, magnesium oxide, and silicon powder, keep warm and stir for 1 - 2 h, add deionized water and γ-aminopropyltriethoxysilane, and keep warm and react for 1 - 2 h to obtain the modified adhesive.

[0017] The reaction principle for the preparation of the modified adhesive is:

[0018] During the reaction process, γ-aminopropyltriethoxysilane is hydrolyzed into silanol under the action of deionized water, and the silanol further undergoes a condensation reaction with the hydroxyl groups on the surfaces of the modified heat-resistant silicone resin, aluminum powder, boron carbide, magnesium oxide, and silicon powder to obtain the modified adhesive modified by a silane coupling agent.

[0019] Further, the dosage ratio of the modified heat-resistant silicone resin, isopropanol, aluminum powder, boron carbide, magnesium oxide, silicon powder, deionized water, and γ-aminopropyltriethoxysilane is 10 - 12 g : 100 - 150 mL : 1 g : 1 g : 0.5 g : 1 g : 5 - 10 mL : 1.5 - 2.5 g.

[0020] Further, the heat-resistant silicone resin is obtained by the following preparation steps:

[0021] C1. Place tetrabutyl titanate in a reaction kettle, heat up to 40 - 50 °C, stir for 1 - 5 min, add a 3,5-heptanedione solution, and keep warm and react for 0.5 - 1 h to obtain a titanium acid mixture;

[0022] The reaction principle for the preparation of the titanium acid mixture is:

[0023] During the reaction process, at 40 - 50 °C, the titanium center of tetrabutyl titanate chelates and coordinates with the β-diketone group of 3,5-heptanedione to form a stable six-membered ring complex. This coordination can inhibit the rapid hydrolysis of tetrabutyl titanate, prevent premature precipitation, regulate the rate of subsequent polycondensation reactions. At the same time, the alkyl chains of 3,5-heptanedione limit the excessive crosslinking of hydrolysis products through steric hindrance effects, promoting the formation of a linear or low-branched prepolymer structure, and obtaining a mixed titanic acid solution.

[0024] C2. Place the mixed titanic acid solution, n-butanol, methyltriethoxysilane, and phenyltrimethoxysilane in a reaction kettle, add a catalyst, heat up to 50 - 60 °C, keep the temperature for reaction for 4 - 5 h, and perform post-treatment to obtain a heat-resistant silicone resin.

[0025] The preparation reaction principle of the heat-resistant silicone resin is as follows:

[0026] During the reaction process, under the catalysis of dilute hydrochloric acid, the titanium-oxygen bonds in the mixed titanic acid solution break, and condense with the broken silicon hydroxyl groups of methyltriethoxysilane and phenyltrimethoxysilane to form a Ti-O-Si-O-Si three-dimensional crosslinked structure, obtaining a heat-resistant silicone resin.

[0027] Furthermore, in step C1, the 3,5-heptanedione solution is composed of 3,5-heptanedione and n-butanol in a volume ratio of 1:5, and the dosage ratio of tetrabutyl titanate and the 3,5-heptanedione solution is 8 - 10 g:30 - 40 mL; in step C2, the catalyst is 0.5 - 1 mol / L dilute hydrochloric acid, and the dosage ratio of the mixed titanic acid solution, n-butanol, methyltriethoxysilane, phenyltrimethoxysilane, and the catalyst is 50 - 100 mL:100 - 120 mL:5 - 6 g:5 - 6 g:1 - 2 mL. The post-treatment steps include: after the reaction is completed, heat up to 110 - 120 °C, and perform vacuum distillation until no liquid is drawn out to obtain a heat-resistant silicone resin.

[0028] A preparation method of a magnetic composite clay includes the following steps:

[0029] S1. Place kaolin, a modified binder, hydromica, and quartz sand in a reaction kettle, stir rapidly for 1 - 5 min, add modified nano-ferroferric oxide in three portions, heat up to 45 - 55 °C, and keep the temperature for reaction for 0.5 - 1 h to obtain a composite clay precursor.

[0030] The preparation reaction principle of the composite clay precursor:

[0031] During the reaction process, the amino group of the modified binder undergoes a nucleophilic reaction with the epoxy group of the modified nano-ferroferric oxide to form a chemical bond, obtaining a composite clay precursor.

[0032] S2. Add deionized water to the composite clay precursor in portions. After each addition of deionized water, seal and let it stand still for 5 - 10 min until the clay is formed to obtain the composite clay.

[0033] Application of a magnetic composite clay. The composite clay prepared by the preparation method of a magnetic composite clay is applied to a magnetic teapot.

[0034] The present invention has the following beneficial effects:

[0035] 1. In the present invention, modified nano - magnetite with a hollow structure is prepared by the solvothermal method, and heat - resistant silicone resin containing a titanium source is prepared by the sol - gel method. Further, inorganic fillers are added to the heat - resistant silicone resin to obtain a modified adhesive. The modified nano - magnetite provides magnetism, the modified adhesive is used as a cross - linker, and kaolin, sericite and quartz sand are used as substrates to obtain the magnetic composite clay. The modified nano - magnetite prepared by the solvothermal method in the present invention has a hollow structure, which improves the specific surface area and magnetic response performance of the nano - magnetite, enabling it to quickly absorb and convert more energy under the action of an external magnetic field. Under an alternating magnetic field, the nano - particles with a hollow structure can more efficiently perform heat energy conversion, generate more heat, and improve the heat conversion performance of the composite clay. At the same time, the hollow structure reduces the overall density of the nano - magnetite, which helps to improve the thermal conductivity of the composite clay, enabling the heat to be evenly distributed in the composite clay. Meanwhile, the increase in magnetization intensity helps to inhibit the precipitation of calcium and magnesium ions in water and improve the taste of the water in the teapot. By modifying epoxy groups on the crude nano - magnetite with a silane coupling agent, further chemical cross - linking is formed with the modified adhesive during the preparation of the composite clay, improving the mechanical strength after the composite clay is cured.

[0036] 2. The present invention also prepares a heat-resistant silicone resin containing titanium atoms by the sol-gel method. The bond energy of the Ti-O bond is higher than that of the Si-O bond, which can further enhance the high-temperature resistance of the silicone resin. Moreover, the introduction of titanium atoms increases the crosslinking sites in the silicone resin, forming a denser three-dimensional network, inhibiting the movement of molecular segments at high temperatures, thereby delaying the thermal decomposition of the silicone resin, improving the thermal stability during the curing of the composite clay, and reducing the structural damage caused by thermal expansion at high temperatures. A modified adhesive is prepared by mixing the heat-resistant silicone resin with aluminum powder, boron carbide, magnesium oxide, and silicon powder. Among them, the silicon powder and aluminum powder form chemical bonding with the Ti-O-Si network in the heat-resistant silicone resin, constituting a multi-level crosslinked structure, enhancing the strength and high-temperature resistance of the cured adhesive. The boron atoms generated by the decomposition of boron carbide form covalent bonds with titanium atoms, and cooperate with the Ti-O-Si network in the heat-resistant silicone resin to construct a high-temperature resistant framework, jointly improving the high-temperature resistance of the composite clay with the silicon powder and aluminum powder. Adding an appropriate amount of magnesium oxide to the adhesive can improve the adhesion performance of the adhesive, avoiding the thermal stress concentration caused by the thermal expansion mismatch between the clay component and nano-magnetic iron tetroxide in the composite clay at high temperatures, and improving the mechanical strength of the cured composite clay. Detailed Embodiments

[0037] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0038] The palladium-carbon used in the present invention is purchased from Suqian Yisheng Metal Materials Co., Ltd., and the palladium content is 1%-20%;

[0039] The quartz sand used in the present invention is purchased from Lianyungang Haosen Mineral Products Co., Ltd., and the particle size is 70-120 mesh;

[0040] The hydromica used in the present invention is purchased from Lingshou County Dongshi Mineral Products Processing Factory, and the particle size is 325 mesh.

[0041] Example 1

[0042] This example provides a method for preparing a magnetic composite clay, including the following steps:

[0043] S1. Prepare modified nano-ferroferric oxide

[0044] Mix 0.5 g of sodium acetate and 20 mL of ethylene glycol evenly to obtain a sodium acetate solution for standby;

[0045] Weigh: 20 g of ferric chloride hexahydrate, 0.5 g of sodium citrate and 300 mL of ethylene glycol, place them in a reaction kettle, stir for 1 min, add 150 mL of sodium acetate solution, heat up to 190 °C, keep the temperature for reaction for 12 h. After the reaction is completed, wait for the reaction solution to cool to room temperature, carry out suction filtration, wash the filter cake once with deionized water and ethanol, transfer it to a drying oven at 50 °C, and dry to constant weight to obtain crude nano-ferroferric oxide;

[0046] Mix zirconia with a diameter of 9 mm and zirconia with a diameter of 14 mm evenly according to the mass ratio of 4:1 to obtain ball-milling media for standby;

[0047] Weigh: 100 g of crude nano-ferroferric oxide, 80 mL of deionized water, 1000 mL of ethanol, 40 g of γ-glycidoxypropyltrimethoxysilane and 1000 g of ball-milling media, place them in a planetary ball mill, ball-mill for 2 h. After the reaction is completed, wash the product once with ethanol, transfer it to an oven at 55 °C, dry to constant weight, and pass through a 200-mesh sieve to obtain modified nano-ferroferric oxide.

[0048] S2. Prepare modified adhesive

[0049] Mix 3,5-heptanedione and n-butanol evenly according to the volume ratio of 1:5 to obtain 3,5-heptanedione solution for standby;

[0050] Weigh: 80 g of tetrabutyl titanate, place it in a reaction kettle, heat up to 40 °C, stir for 1 min, add 300 mL of 3,5-heptanedione solution, and keep the temperature for reaction for 0.5 h to obtain a titanic acid mixture;

[0051] Weigh: 500 mL of titanic acid mixture, 1000 mL of n-butanol, 50 g of methyltriethoxysilane and 50 g of phenyltrimethoxysilane, place them in a reaction kettle, add 10 mL of 0.5 mol / L dilute hydrochloric acid, heat up to 50 °C, keep the temperature for reaction for 4 h. After the reaction is completed, heat up to 110 °C and carry out vacuum distillation until no liquid is drawn out to obtain heat-resistant silicone resin;

[0052] Weigh: 100 g of modified heat-resistant silicone resin and 1000 mL of isopropanol, place them in a reaction kettle, heat up to 30 °C, keep the temperature and stir for 5 min, add 10 g of aluminum powder, 10 g of boron carbide, 5 g of magnesium oxide and 10 g of silicon powder, keep the temperature and stir for 1 h, add 50 mL of deionized water and 15 g of γ-aminopropyltriethoxysilane, and keep the temperature for reaction for 1 h to obtain modified adhesive.

[0053] S4. Prepare composite clay

[0054] Weigh by weight: 10 parts of modified nano-ferroferric oxide, 60 parts of kaolin, 2 parts of modified adhesive, 11 parts of muscovite and 8 parts of quartz sand for standby;

[0055] Put kaolin, modified binder, hydromica and quartz sand into a reaction kettle, stir rapidly for 1 min, add modified nano-ferroferric oxide in three portions, heat up to 45 °C, keep the temperature for reaction for 0.5 h to obtain a composite clay precursor;

[0056] Add deionized water to the composite clay precursor in portions. After adding deionized water each time, seal and let it stand still for 5 min until the clay is formed to obtain the composite clay.

[0057] Example 2

[0058] This example provides a preparation method of magnetic composite clay, including the following steps:

[0059] S1. Prepare modified nano-ferroferric oxide

[0060] Mix sodium acetate and ethylene glycol in a dosage ratio of 0.7 g:23 mL evenly to obtain a sodium acetate solution for standby;

[0061] Weigh: 30 g of ferric chloride hexahydrate, 0.7 g of sodium citrate and 350 mL of ethylene glycol, put them into a reaction kettle, stir for 3 min, add 170 mL of sodium acetate solution, heat up to 195 °C, keep the temperature for reaction for 13 h. After the reaction is completed, wait for the reaction solution to cool to room temperature, carry out suction filtration, wash the filter cake with deionized water and ethanol twice, transfer it to a drying oven at 55 °C, and dry it to constant weight to obtain crude nano-ferroferric oxide;

[0062] Mix zirconia with a diameter of 9 mm and zirconia with a diameter of 14 mm evenly according to a mass ratio of 4:1 to obtain ball milling media for standby;

[0063] Weigh: 125 g of crude nano-ferroferric oxide, 90 mL of deionized water, 1200 mL of ethanol, 50 g of γ-glycidoxypropyltrimethoxysilane and 1200 g of ball milling media, put them into a planetary ball mill, ball mill for 3 h. After the reaction is completed, wash the product with ethanol twice, transfer it to an oven at 60 °C, dry it to constant weight, and sieve it through a 200-mesh sieve to obtain modified nano-ferroferric oxide.

[0064] S2. Prepare modified binder

[0065] Mix 3,5-heptanedione and n-butanol evenly according to a volume ratio of 1:5 to obtain a 3,5-heptanedione solution for standby;

[0066] Weigh: 90 g of tetrabutyl titanate, put it into a reaction kettle, heat up to 45 °C, stir for 3 min, add 350 mL of 3,5-heptanedione solution, and keep the temperature for reaction for 1 h to obtain a titanium acid mixture;

[0067] Weigh: 700 mL of titanic acid mixture, 1100 mL of n-butanol, 55 g of methyltriethoxysilane, and 55 g of phenyltrimethoxysilane and place them in a reaction kettle. Add 15 mL of 1 mol / L dilute hydrochloric acid, heat up to 55 °C, and keep the temperature for reaction for 4.5 h. After the reaction is completed, heat up to 115 °C and perform vacuum distillation until no liquid is drawn out to obtain a heat-resistant silicone resin;

[0068] Weigh: 110 g of modified heat-resistant silicone resin and 1250 mL of isopropanol and place them in a reaction kettle. Heat up to 35 °C and keep stirring for 7 min. Add 10 g of aluminum powder, 10 g of boron carbide, 5 g of magnesium oxide, and 10 g of silicon powder, keep stirring for 1.5 h, add 70 mL of deionized water and 20 g of γ-aminopropyltriethoxysilane, and keep the temperature for reaction for 1.5 h to obtain a modified adhesive.

[0069] S4. Prepare composite clay

[0070] Weigh by parts by weight: 11 parts of modified nano-ferroferric oxide, 65 parts of kaolin, 3 parts of modified adhesive, 13 parts of sericite, and 9 parts of quartz sand, and set aside;

[0071] Place kaolin, modified adhesive, sericite, and quartz sand in a reaction kettle, stir rapidly for 3 min, add modified nano-ferroferric oxide in three portions, heat up to 50 °C, and keep the temperature for reaction for 1 h to obtain a composite clay precursor;

[0072] Add deionized water to the composite clay precursor in portions. After each addition of deionized water, it is necessary to seal and let it stand for 7 min until the clay is formed to obtain composite clay.

[0073] Example 3

[0074] This example provides a method for preparing magnetic composite clay, including the following steps:

[0075] S1. Prepare modified nano-ferroferric oxide

[0076] Mix sodium acetate and ethylene glycol in a ratio of 1 g:25 mL evenly to obtain a sodium acetate solution, and set aside;

[0077] Weigh: 50 g of ferric chloride hexahydrate, 1 g of sodium citrate, and 400 mL of ethylene glycol and place them in a reaction kettle. Stir for 5 min, add 200 mL of sodium acetate solution, heat up to 200 °C, and keep the temperature for reaction for 15 h. After the reaction is completed, wait for the reaction solution to cool to room temperature, perform suction filtration, wash the filter cake with deionized water and ethanol twice, transfer it to a drying oven at 60 °C, and dry to constant weight to obtain a crude product of nano-ferroferric oxide;

[0078] Mix zirconia with a diameter of 9 mm and zirconia with a diameter of 14 mm evenly according to a mass ratio of 4:1 to obtain a ball milling medium, and set aside;

[0079] Weigh: 150 g of crude nano-ferroferric oxide, 100 mL of deionized water, 1500 mL of ethanol, 60 g of γ-glycidoxypropyltrimethoxysilane and 1500 g of ball-milling medium, place them in a planetary ball mill, ball-mill for 4 h. After the reaction is completed, wash the product twice with ethanol, transfer it to an oven at 65 °C, dry to constant weight, and pass through a 200-mesh sieve to obtain modified nano-ferroferric oxide.

[0080] S2. Preparation of modified adhesive

[0081] Mix 3,5-heptanedione and n-butanol evenly according to a volume ratio of 1:5 to obtain a 3,5-heptanedione solution for standby.

[0082] Weigh: 100 g of tetrabutyl titanate and place it in a reaction kettle, heat up to 50 °C, stir for 5 min, add 400 mL of the 3,5-heptanedione solution, and keep the temperature for reaction for 1 h to obtain a titanium acid mixture.

[0083] Weigh: 1000 mL of the titanium acid mixture, 1200 mL of n-butanol, 60 g of methyltriethoxysilane and 60 g of phenyltrimethoxysilane, place them in a reaction kettle, add 20 mL of 1 mol / L dilute hydrochloric acid, heat up to 60 °C, keep the temperature for reaction for 5 h. After the reaction is completed, heat up to 120 °C and carry out vacuum distillation until no liquid is collected to obtain a heat-resistant silicone resin.

[0084] Weigh: 120 g of modified heat-resistant silicone resin and 1500 mL of isopropanol, place them in a reaction kettle, heat up to 40 °C, keep the temperature and stir for 10 min, add 10 g of aluminum powder, 10 g of boron carbide, 5 g of magnesium oxide and 10 g of silicon powder, keep the temperature and stir for 2 h, add 100 mL of deionized water and 25 g of γ-aminopropyltriethoxysilane, keep the temperature for reaction for 2 h to obtain a modified adhesive.

[0085] S4. Preparation of composite clay

[0086] Weigh by weight: 12 parts of modified nano-ferroferric oxide, 70 parts of kaolin, 4 parts of modified adhesive, 15 parts of muscovite and 11 parts of quartz sand for standby.

[0087] Place kaolin, modified adhesive, muscovite and quartz sand in a reaction kettle, stir rapidly for 5 min, add modified nano-ferroferric oxide in three portions, heat up to 55 °C, and keep the temperature for reaction for 1 h to obtain a composite clay precursor.

[0088] Add deionized water to the composite clay precursor in portions. After each addition of deionized water, seal and let it stand for 10 min until the clay is formed to obtain composite clay.

[0089] Comparative Example 1

[0090] The difference between this comparative example and Example 2 is that when preparing the modified nano-ferroferric oxide in step S1, the solid nano-ferroferric oxide is used to replace the crude nano-ferroferric oxide in equal amount.

[0091] Comparative Example 2

[0092] The difference between this comparative example and Example 2 is that when preparing the modified nano-ferroferric oxide in step S1, γ-glycidoxypropyltrimethoxysilane is not added.

[0093] Comparative Example 3

[0094] The difference between this comparative example and Example 2 is that when preparing the modified adhesive in step S2, MQ silicone resin is used to replace the heat-resistant silicone resin in equal amount.

[0095] Comparative Example 4

[0096] The difference between this comparative example and Example 2 is that when preparing the modified adhesive in step S2, magnesium oxide is not added.

[0097] Performance test:

[0098] The composite clays prepared in Examples 1-3 and Comparative Examples 1-4 are kneaded into teapot blanks, and then transferred to a sintering furnace. After introducing nitrogen protection in the sintering furnace, the temperature is raised to 500 °C at a rate of 2 °C / min in sequence, held for 2 h, then the temperature is raised to 1000 °C at a rate of 5 °C / min, held for 3 h, and then the temperature is raised to 1200 °C at a rate of 3 °C / min, held for 2 h, and then cooled naturally to obtain teapot specimens;

[0099] Referring to the standard YB / T 4857-2020 "Semi-siliceous insulating refractory bricks", the heating permanent linear change rate of the teapot specimens prepared in Examples 1-3 and Comparative Examples 1-4 above is tested;

[0100] Referring to the standard GB / T 23294-2021 "Wear-resistant refractory materials", the room-temperature wear resistance and thermal conductivity of the teapot specimens prepared in Examples 1-3 and Comparative Examples 1-4 above are tested;

[0101] Referring to the standard GB / Z 26082-2010 "Measurement method for direct-current magnetic susceptibility (magnetic moment) of nanomaterials", the magnetization intensity of the teapot specimens prepared in Examples 1-3 and Comparative Examples 1-4 above is tested, and the specific data are shown in Table 1.

[0102] Table 1 - Performance test data table of each specimen

[0103]

[0104]

[0105] Data analysis:

[0106] Comparing and analyzing the data in Table 1 above, the heating permanent linear change rate of the teapot sample prepared by the present invention is 0.72%, and the wear resistance at room temperature is 2.2 cm 3 , the flexural strength at room temperature is 64.4 MPa, the thermal conductivity is 180.4 W·(m·K) -1 and the magnetization intensity is 1.4×10 3 A·m -1 . All the data are better than those of the comparative example;

[0107] Data analysis:

[0108] By comparing and analyzing the data of Comparative Example 1 and Example 2, it can be seen that the heating permanent linear change rate, wear resistance at room temperature, flexural strength at room temperature, thermal conductivity and magnetization intensity of the teapot sample prepared in Comparative Example 1 decreased significantly. This shows that the modified nano-ferroferric oxide prepared by the solvothermal method in the present invention has a hollow structure, which increases the specific surface area and magnetic response performance of nano-ferroferric oxide, enabling it to quickly absorb and convert more energy under the action of an external magnetic field. Under an alternating magnetic field, the nano-particles with a hollow structure can more efficiently perform heat energy conversion, generate more heat, and improve the heat conversion performance of the composite clay. At the same time, the hollow structure reduces the overall density of nano-ferroferric oxide, which helps to improve the thermal conductivity of the composite clay and enables heat to be evenly distributed in the composite clay;

[0109] By comparing and analyzing the data of Comparative Example 2 and Example 2, it can be seen that the wear resistance at room temperature and flexural strength at room temperature of the teapot sample prepared in Comparative Example 2 decreased significantly. This shows that the present invention modifies epoxy groups on the crude nano-ferroferric oxide through a silane coupling agent, and further forms a chemical crosslink with the modified binder when preparing the composite clay, improving the mechanical strength after the composite clay is cured;

[0110] By comparing and analyzing the data of Comparative Example 3 and Example 2, it can be seen that the heating permanent linear change rate of the teapot sample prepared in Comparative Example 3 decreased significantly. This shows that the present invention prepares a heat-resistant silicone resin containing titanium atoms by the sol-gel method. The bond energy of the Ti-O bond is higher than that of the Si-O bond, which can further enhance the high-temperature resistance of the silicone resin. Moreover, the introduction of titanium atoms increases the crosslinking sites in the silicone resin, forming a denser three-dimensional network, inhibiting the movement of molecular segments at high temperatures, thereby delaying the thermal decomposition of the silicone resin, improving the thermal stability during the curing of the composite clay, and reducing the structural damage caused by thermal expansion at high temperatures;

[0111] By comparing and analyzing the data of Comparative Example 4 and Example 2, it can be seen that the heating permanent linear change rate, normal temperature abrasion resistance, and normal temperature flexural strength of the teapot specimens prepared in Comparative Example 4 have decreased significantly. This shows that in the present invention, a modified adhesive is prepared by mixing heat-resistant silicone resin with aluminum powder, boron carbide, magnesium oxide, and silicon powder. Among them, silicon powder and aluminum powder form chemical bonds with the Ti-O-Si network in the heat-resistant silicone resin, constituting a multi-level cross-linked structure, which improves the strength and high-temperature resistance of the cured adhesive. Boron atoms generated by the decomposition of boron carbide form covalent bonds with titanium atoms, and cooperate with the Ti-O-Si network in the heat-resistant silicone resin to construct a high-temperature resistant skeleton, and together with silicon powder and aluminum powder, improve the high-temperature resistance of the composite clay. Adding an appropriate amount of magnesium oxide to the adhesive can improve the adhesion performance of the adhesive, avoid the thermal stress concentration caused by the thermal expansion mismatch between the clay component and nano-magnetic iron oxide at high temperature, and improve the mechanical strength of the cured composite clay.

[0112] The above are only examples and descriptions of the structure of the present invention. Those skilled in the art of the present technology can make various modifications or supplements or use similar methods to replace the specific embodiments described, as long as they do not deviate from the structure of the invention or exceed the scope defined by this claim book, they should all belong to the protection scope of the present invention.

Claims

1. A magnetic composite clay, characterized in that: Ferric chloride hexahydrate, sodium citrate and ethylene glycol are placed in a reaction kettle, stirred for 1-5 minutes, sodium acetate solution is added, the temperature is raised to 190-200°C, the temperature is kept for reaction for 12-15 hours, and a crude nano-ferroferric oxide product is obtained by post-treatment. The crude nano-ferroferric oxide product, deionized water, ethanol, γ-glycidyloxypropyltrimethoxysilane and ball milling medium are then placed in a planetary ball mill, ball milled for 2-4 hours, and a modified nano-ferroferric oxide product is obtained by post-treatment. Place the modified heat-resistant silicone resin and isopropanol in a reaction kettle, heat to 30-40°C, keep warm and stir for 5-10 minutes, add aluminum powder, boron carbide, magnesium oxide and silicon powder, keep warm and stir for 1-2 hours, add deionized water and γ-aminopropyltriethoxysilane, keep warm and react for 1-2 hours to obtain a modified adhesive; Among them, by weight, 10-12 parts of the modified nano-ferroferric oxide, 2-4 parts of the modified adhesive, 60-70 parts of kaolin, 11-15 parts of hydromica, and 8-11 parts of quartz sand in the above step are processed together to prepare composite clay.

2. The magnetic composite clay according to claim 1, characterized in that: The sodium acetate solution is composed of sodium acetate and ethylene glycol in a dosage ratio of 0.5-1g:20-25mL, and the dosage ratio of ferric chloride hexahydrate, sodium citrate, ethylene glycol and sodium acetate solution is 2-5g:0.05-0.1g:30-40mL:15-20mL.

3. The magnetic composite clay according to claim 1, characterized in that: The ball milling medium is composed of zirconium oxide with a diameter of 9 mm and zirconium oxide with a diameter of 14 mm in a mass ratio of 4:1, and the usage ratio of the crude nano-ferroferric oxide, deionized water, ethanol, γ-glycidyloxypropyltrimethoxysilane and the ball milling medium is 10-15g:8-10mL:100-150mL:4-6g:100-150g.

4. The magnetic composite clay according to claim 1, characterized in that: The usage ratio of the modified heat-resistant silicone resin, isopropyl alcohol, aluminum powder, boron carbide, magnesium oxide, silicon powder, deionized water and γ-aminopropyltriethoxysilane is 10-12g:100-150mL:1g:1g:0.5g:1g:5-10mL:1.5-2.5g.

5. The magnetic composite clay according to claim 1, characterized in that: The heat-resistant silicone resin is obtained by the following preparation steps: C1. Place tetrabutyl titanate in a reaction kettle, heat to 40-50°C, stir for 1-5 minutes, add 3,5-heptanedione solution, and keep the temperature for 0.5-1 hour to obtain a titanate mixed solution; C2. Place titanic acid mixed solution, n-butanol, methyltriethoxysilane and phenyltrimethoxysilane in a reaction kettle, add a catalyst, raise the temperature to 50-60°C, keep the temperature for reaction for 4-5 hours, and post-treat to obtain a heat-resistant silicone resin.

6. The magnetic composite clay according to claim 5, characterized in that: In step C1, the 3,5-heptanedione solution is composed of 3,5-heptanedione and n-butanol in a volume ratio of 1:5, and the amount ratio of tetrabutyl titanate to 3,5-heptanedione solution is 8-10 g:30-40 mL.

7. The magnetic composite clay according to claim 5, characterized in that: In step C2, the catalyst is 0.5-1 mol / L dilute hydrochloric acid, and the dosage ratio of the titanic acid mixture, n-butanol, methyltriethoxysilane, phenyltrimethoxysilane and the catalyst is 50-100 mL: 100-120 mL: 5-6 g: 5-6 g: 1-2 mL.

8. The method for preparing a magnetic composite clay according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Place kaolin, modified binder, hydromica and quartz sand in a reaction kettle, stir rapidly for 1-5 minutes, add modified nano-ferroferric oxide three times, heat to 45-55°C, and keep the temperature for 0.5-1h to obtain a composite clay precursor; S2. Add deionized water to the composite clay precursor in portions. After each addition of deionized water, seal and let stand for 5-10 minutes until the clay is formed to obtain composite clay.

9. An application of magnetic composite clay, characterized in that: The magnetic composite clay according to any one of claims 1 to 7 is applied to teapot processing.

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