Refractory heat-insulating brick with improved structure and manufacturing method of refractory heat-insulating brick

Abstract

The invention relates to the field of refractory materials, and discloses a refractory heat-insulating brick with an improved structure and a manufacturing method thereof.The refractory heat-insulating brick comprises an outer layer which is directly exposed in a high-temperature and mechanical stress environment, covers the surface of the whole brick body and provides primary protection and fire resistance; the porous heat insulation layer is positioned on the inner side of the outer layer, has lower density and is filled with tiny pores; the fiber grid reinforcing structure is embedded in the porous heat insulation layer to form an internal framework of the brick body, and fiber grids are distributed in the heat insulation layer; the surface hardening layer is located on the surface of the outer layer and formed through surface treatment; and the anti-corrosion coating is an outermost coating layer and covers the outer layer and the surface hardening layer. The fiber grid and the metal framework reinforcing structure are introduced into the brick body, so that the compressive strength and the impact resistance of the brick body are greatly improved, and the refractory brick can still keep a complete structure and is not easy to crack or deform even in a high-temperature and high-mechanical-stress environment.

Description

Technical Field

[0001] The invention relates to the field of refractory materials, in particular to refractory heat-insulating bricks with improved structures and a manufacturing method thereof. Background Art

[0002] Refractory bricks are important materials widely used in high-temperature industries, mainly used for lining and thermal insulation in high-temperature furnaces, heat treatment equipment, chemical plants and other fields. Traditional refractory bricks are usually made of high-purity refractory materials, such as alumina, silica or magnesia, and have high refractoriness and certain mechanical strength. However, with the advancement of industrial technology and the diversification of application needs, the limitations of traditional refractory bricks in high-temperature thermal insulation performance, mechanical strength, chemical corrosion resistance and service life are becoming increasingly apparent, making it difficult to meet the requirements of certain extreme environments.

[0003] First, although traditional refractory bricks have high refractoriness in high temperature environments, their thermal insulation performance is relatively poor, resulting in a large amount of heat being conducted to the outside through the furnace wall, thereby increasing energy consumption and production costs. In addition, traditional refractory bricks are susceptible to thermal shock during long-term high-temperature use, resulting in cracking and damage, affecting the safe operation of equipment. Secondly, with the deepening of industrialization, refractory bricks not only need to withstand high temperatures, but also need to remain stable in chemically corrosive environments such as acidic, alkaline or high-temperature slag. However, ordinary refractory bricks are susceptible to corrosion under these conditions, resulting in a shortened service life and increased maintenance and replacement costs for equipment. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention provides refractory heat-insulating bricks with improved structures and a method for manufacturing the same, which solves the problem that traditional refractory bricks are easily subjected to thermal shock, resulting in cracking and damage during long-term high-temperature use.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: Refractory insulation bricks with improved structure, including:

[0006] Outer layer: directly exposed to high temperature and mechanical stress, covering the entire surface of the brick, providing initial protection and fire resistance;

[0007] Porous insulation layer: Located on the inner side of the outer layer, this layer has a lower density and is full of tiny pores;

[0008] Fiber grid reinforcement structure: embedded inside the porous insulation layer to form the internal skeleton of the brick body, and the fiber grid is distributed in the insulation layer;

[0009] Surface hardened layer: located on the surface of the outer layer, a hardened layer formed by surface treatment;

[0010] Anti-corrosion coating: The outermost coating layer covering the outer layer and the surface hardening layer.

[0011] Preferably, the method for manufacturing the refractory insulating brick with improved structure comprises the following steps:

[0012] S1. Raw material preparation

[0013] Refractory raw material combination selection: including alumina, silica, magnesia and chromite;

[0014] Reinforcement fiber: choose alumina fiber, silica fiber or carbon fiber;

[0015] Nanomaterials: Choose nano-alumina or nano-silicon oxide;

[0016] Foaming agent: choose sodium bicarbonate, borate or phenolic resin;

[0017] S2. Mixing and pulping

[0018] mix:

[0019] Mix the refractory raw materials selected in step S1 according to weight ratio, and add a binder after mixing evenly;

[0020] Grinding:

[0021] Grind the mixed slurry by ball mill or stirring mill and control the grinding time;

[0022] S3, Forming

[0023] Use metal molds or silicone molds, and choose semi-dry molding, slip casting or isostatic pressing;

[0024] S4. Drying

[0025] The formed materials are dried naturally, heated or microwaved;

[0026] S5, Firing

[0027] Heating stage: Firing in a high-temperature kiln, controlling the heating rate;

[0028] Holding stage: After reaching the target firing temperature, the holding time is set according to the thickness and size of the blank;

[0029] Cooling stage: natural cooling or slow cooling is adopted, and the cooling rate is controlled until the blank is cooled to room temperature;

[0030] S6, surface hardening

[0031] Surface carburizing: Place the fired brick body in a carbon-containing atmosphere for carburizing treatment, and control the temperature and time;

[0032] Surface nitriding: Treat the brick surface in a high-temperature nitrogen atmosphere and control the temperature and time.

[0033] Preferably, in step S1, the aluminum oxide content is ≥95%, the silicon oxide content is ≥98%, the magnesia content is ≥95%, the chromite content is ≥98%, the fiber diameter is between 1-5 microns, the length is 1-10 mm, the diameter of the nanomaterial particles is between 10-100 nanometers, and the amount of sodium bicarbonate used is 3-5% by weight.

[0034] Preferably, in the step S2, the refractory raw materials are mixed according to 70%-90% of the matrix material and 10%-30% of the reinforcing material or the foaming agent, the binder includes a phosphate binder and a silicate binder, the addition amount is 5%-10%, and the grinding time is controlled at 2-4 hours until the particle fineness reaches 200-400 mesh.

[0035] Preferably, in the step S3;

[0036] Semi-dry molding: put the slurry with a water content of 5%-10% into the mold and apply a pressure of 20-50MPa to mold;

[0037] Grouting: The slurry is injected into the mold and solidified by natural drying or heating drying;

[0038] Isostatic pressing: Wrap the slurry in a rubber sleeve, place it in an isostatic pressing device, and apply a pressure of 100-200MPa.

[0039] Preferably, in the step S4;

[0040] Natural drying: Place the blank at room temperature for 24-48 hours to allow its moisture to evaporate naturally;

[0041] Heating and drying: Dry in an oven at 60-110℃ for 8-12 hours to accelerate the evaporation of water;

[0042] Microwave drying: Using microwave drying equipment, the temperature is controlled at 70-100℃ and the drying time is 2-4 hours.

[0043] Preferably, in the step S5, the heating rate is controlled at 5-10°C / min, and the holding time is 2-4 hours;

[0044] The firing temperature range is as follows:

[0045] Alumina based bricks: 1500-1600℃

[0046] Silica based bricks: 1400-1500℃

[0047] Magnesia based brick: 1600-1700℃

[0048] Chromite-based bricks: 1600-1700℃

[0049] The cooling rate is controlled at 5-10°C / min until the blank is cooled to room temperature.

[0050] Preferably, in the step S6, the temperature of the surface carburizing is controlled at 900-1100° C. for 2-4 hours, and the temperature of the surface nitriding is controlled at 800-1000° C. for 4-6 hours.

[0051] Preferably, after the step S3, skeleton reinforcement is performed;

[0052] Fiber mesh embedding: During the molding process, an alumina fiber mesh or a carbon fiber mesh is embedded in the slurry to form the internal skeleton structure of the brick body;

[0053] Metal skeleton reinforcement: Stainless steel or high temperature resistant alloy wire mesh or skeleton is embedded during the forming process.

[0054] Preferably, after the step S6, surface coating is performed;

[0055] Anti-corrosion coating: A layer of acid-resistant or alkali-resistant coating, including zirconium silicate and aluminum silicate coating, is applied to the surface of the brick, and then a secondary firing is performed, and the temperature is controlled at 1200-1400℃;

[0056] Reflective coating: Titanium oxide coating is applied on the surface of the brick.

[0057] The present invention provides a refractory heat-insulating brick with an improved structure and a manufacturing method thereof, which has the following beneficial effects:

[0058] 1. The present invention greatly improves the compressive strength and impact resistance of the brick body by introducing a fiber grid and a metal skeleton reinforcement structure inside the brick body. In this way, even under high temperature and high mechanical stress environments, the refractory bricks can still maintain structural integrity and are not easily cracked or deformed.

[0059] 2. The present invention designs a porous structure in the brick body and uses a foaming agent to form uniform micropores. This brick has a lower thermal conductivity (0.3-0.9W / m·K), which significantly reduces heat conduction, improves thermal insulation, saves energy and protects external equipment and the environment from high temperature.

[0060] 3. The present invention adopts anti-corrosion coating (such as zirconium silicate, aluminum silicate and titanium oxide coating) and surface treatment process (such as carburizing and nitriding), and the refractory bricks have strong resistance to chemical substances such as acid, alkali and slag, which enables it to maintain structural stability for a long time in chemical, metallurgical and other environments, reducing maintenance frequency and cost.

[0061] 4. By selecting appropriate foaming agents and process control, the weight of the bricks in some embodiments is significantly reduced (for example, 1800-2200 kg / m3 ), which not only reduces the load on the overall structure, but also makes the bricks easier to handle and install during construction, and is especially suitable for use in application scenarios where the weight of the equipment needs to be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 The present invention is a flow chart of a method for manufacturing refractory insulation bricks with improved structure. DETAILED DESCRIPTION

[0063] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. 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 creative work are within the scope of protection of the present invention.

[0064] Please refer to the attached Figure 1 The embodiment of the present invention provides a refractory heat-insulating brick with an improved structure, comprising:

[0065] Outer layer: This is the outermost layer of the brick body, directly exposed to high temperature and mechanical stress. It covers the surface of the entire brick body, providing initial protection and fire resistance.

[0066] Porous insulation layer: Located inside the high-density outer layer. This layer has a lower density and is full of tiny pores. Its main function is to insulate. It reduces the speed at which heat is conducted from the outside to the inside of the brick.

[0067] Fiber grid reinforcement structure: This structure is embedded inside the porous insulation layer, forming the internal skeleton of the brick. The fiber grid is distributed in the insulation layer, which plays a reinforcing role and improves the crack resistance and structural strength of the brick.

[0068] Surface hardening layer: This layer is located on the surface of the high-density outer layer and is a hardened layer formed by surface treatment. It makes the brick surface stronger and increases wear resistance and impact resistance.

[0069] Anti-corrosion coating: This is the outermost coating layer, covering the high-density outer layer and the surface hardening layer. Its main function is to protect the brick from chemical corrosion, especially in acidic or alkaline environments.

[0070] Specifically,

[0071] 1. Multi-layer composite structure

[0072] High refractory layer: The outer layer of the brick body is made of high-density, high-refractory materials, which have strong resistance to thermal shock and wear. This layer is mainly used to directly withstand high temperatures and mechanical stress.

[0073] Insulation layer: The internal structure contains a low-density, porous insulation layer. The main function of this layer is to reduce thermal conductivity, reduce heat loss, and improve the thermal insulation performance of the entire brick body.

[0074] 2. Microporous structure

[0075] Evenly distributed micropores: By controlling the use of foaming agent, a large number of evenly distributed micropores are formed inside the brick body, with a pore size between 0.1 and 1 mm. These microporous structures help reduce the thermal conductivity of the brick body while maintaining a certain mechanical strength.

[0076] Controllable Porosity: The porosity of the brick can be adjusted between 20%-50% according to application requirements to balance thermal insulation performance and structural strength.

[0077] 3. Strengthen the skeleton structure

[0078] Fiber-reinforced grid: Alumina fiber grid or carbon fiber grid is embedded inside the brick to form an internal skeleton structure. This skeleton significantly improves the crack resistance, tensile strength and impact resistance of the brick, especially in high mechanical stress environments.

[0079] Metal skeleton reinforcement: For applications requiring higher mechanical strength, a metal skeleton (such as stainless steel or high-temperature resistant alloy steel wire mesh) can be embedded inside the brick. This design enables the brick to maintain structural integrity under extreme temperature and pressure.

[0080] 4. Surface hardening treatment

[0081] Carburized layer: After the surface is carburized, a hardened carbonized layer is formed. This carbonized layer significantly improves the hardness and corrosion resistance of the brick surface, and is suitable for high-wear and high-corrosion working environments.

[0082] Nitriding layer: The nitriding layer formed by surface nitriding treatment makes the brick body have higher wear resistance and oxidation resistance, and performs well in high-temperature furnace linings.

[0083] 5. Chemical corrosion resistant coating

[0084] Anti-corrosion coating: The surface is coated with acid-resistant or alkali-resistant coating, such as zirconium silicate or aluminum silicate. This coating can effectively prevent chemical corrosion of the brick in acidic or alkaline environments and is suitable for special applications in the chemical industry.

[0085] High reflective coating: Coating the surface with a high reflectivity coating (such as titanium oxide coating) can reflect a large amount of thermal radiation, further reducing the thermal conductivity of the brick, and is suitable for thermal insulation applications in extremely high temperature environments.

[0086] A method for manufacturing a refractory heat-insulating brick with an improved structure, according to claim 1, characterized in that it comprises the following steps:

[0087] S1. Raw material preparation

[0088] Selection of refractory raw materials: mainly including high-purity alumina (Al2O3, content ≥95%), silicon oxide (SiO2, content ≥98%), magnesia (MgO, content ≥95%), chromite (Cr2O3, content ≥98%). Select the appropriate raw material combination according to the performance requirements of the final product.

[0089] Reinforcements:

[0090] Reinforcement fiber: Choose alumina fiber, silica fiber or carbon fiber, with a fiber diameter between 1-5 microns and a length of 1-10 mm.

[0091] Nanomaterials: nano-alumina or nano-silicon oxide, with particle diameters between 10-100 nanometers.

[0092] Blowing agent: Sodium bicarbonate (NaHCO3, used in an amount of 3-5 weight %), borate or phenolic resin blowing agent is used to form a microporous structure.

[0093] S2. Mixing and pulping

[0094] mix:

[0095] The selected refractory raw materials are mixed according to a weight ratio (70%-90% of matrix material and 10%-30% of reinforcing material or foaming agent).

[0096] After mixing evenly, add a binder (phosphate binder, silicate binder, added in an amount of 5%-10%) to form a uniform slurry.

[0097] Grinding: Grind the mixed slurry by ball mill or stirred mill for 2-4 hours until the particle size reaches 200-400 mesh.

[0098] S3, Forming

[0099] Mold preparation:

[0100] Use metal molds or silicone molds, make sure the mold size meets the design requirements, and keep it clean and dry.

[0101] Molding method:

[0102] Semi-dry molding: put the slurry with a moisture content of 5%-10% into the mold and apply a pressure of 20-50MPa to form it. It is suitable for larger bricks.

[0103] Grouting molding: The slurry is injected into the mold and cured by natural drying or heating. It is suitable for bricks with complex shapes or thin walls.

[0104] Isostatic pressing: Wrap the slurry in a rubber sleeve, place it in an isostatic pressing device, and apply a pressure of 100-200MPa to make the brick body uniform in density, which is suitable for high-precision and high-density products.

[0105] S4. Drying

[0106] The formed materials are dried naturally, heated or microwaved;

[0107] Natural drying: Place the blank at room temperature for 24-48 hours to allow its moisture to evaporate naturally.

[0108] Heating and drying: Dry in an oven at 60-110℃ for 8-12 hours to accelerate the evaporation of moisture and avoid cracks.

[0109] Microwave drying: Using microwave drying equipment, the temperature is controlled at 70-100℃, and the drying time is 2-4 hours. It is suitable for rapid drying and preventing deformation of the green body.

[0110] S5, Firing

[0111] Heating stage: Firing is carried out in a high-temperature kiln, and the heating rate is controlled at 5-10℃ / minute to prevent thermal stress cracks in the green body.

[0112] Insulation stage: After reaching the target firing temperature, the insulation time is determined according to the thickness and size of the blank, which is 2-4 hours. The firing temperature range is as follows:

[0113] Alumina based bricks: 1500-1600℃

[0114] Silica based bricks: 1400-1500℃

[0115] Magnesia based brick: 1600-1700℃

[0116] Chromite-based bricks: 1600-1700℃

[0117] Cooling stage: natural cooling or slow cooling, the cooling rate is controlled at 5-10℃ / min, until the blank is cooled to room temperature.

[0118] S6, surface hardening

[0119] Surface carburizing: The fired brick is placed in a carbon-containing atmosphere for carburizing treatment, with the temperature controlled at 900-1100°C for 2-4 hours. Carburizing can enhance the hardness and corrosion resistance of the brick surface, and is suitable for high-temperature furnace linings in the metallurgical industry.

[0120] Surface nitriding: Treat the surface of the brick in a high-temperature nitrogen atmosphere, with the temperature controlled at 800-1000℃ for 4-6 hours. Nitriding can improve the wear resistance and oxidation resistance of the brick.

[0121] After step S3, skeleton enhancement is performed;

[0122] Fiber mesh embedding: During the molding process, an alumina fiber mesh or a carbon fiber mesh is embedded in the slurry to form the internal skeleton structure of the brick. This design can significantly improve the crack resistance and tensile strength of the brick, and is suitable for applications with high mechanical stress.

[0123] Metal skeleton reinforcement: Stainless steel or high-temperature resistant alloy steel mesh or skeleton is embedded in the molding process to further enhance the mechanical strength and impact resistance of the brick body, making it suitable for use under extreme working conditions.

[0124] After step S6, surface coating is performed;

[0125] Anti-corrosion coating: A layer of acid-resistant or alkali-resistant coating (zirconium silicate, aluminum silicate coating) is applied to the surface of the brick, and then a secondary firing is performed (the temperature is controlled at 1200-1400℃). This treatment can improve the chemical corrosion resistance of the brick in the chemical industry.

[0126] Reflective coating: A high-reflectivity coating (titanium oxide coating) is applied to the surface of the brick to further reduce thermal conductivity and enhance thermal insulation performance by reflecting thermal radiation. It is particularly suitable for high-temperature furnace roofs or side walls.

[0127] The following is a description of the materials used in the manufacturing process of improved structural refractory insulation bricks:

[0128] 1. Alumina (Al2O3)

[0129] Function: Alumina is a highly refractory material with excellent wear resistance and high temperature stability. It is often used as the main component of refractory bricks, especially for the lining of high temperature kilns.

[0130] Content requirement: Alumina content is required to be ≥95% to ensure the purity and performance of the material.

[0131] 2. Silicon oxide (SiO2)

[0132] Function: Silicon oxide has good refractory properties and is widely used in the manufacture of refractory materials and insulation bricks. It can resist the erosion of acidic slag and remain stable at high temperatures.

[0133] Content requirement: Silicon oxide content must be ≥98% to ensure the purity and high temperature resistance of the material.

[0134] 3. Magnesia (MgO)

[0135] Function: Magnesia is mainly composed of magnesium oxide, which has extremely high refractoriness and good resistance to alkaline slag erosion. It is often used in refractory materials in the metallurgical industry.

[0136] Content requirement: The magnesia content is required to be ≥95% to ensure its ability to resist high temperature and chemical corrosion.

[0137] 4. Chromite (Cr2O3)

[0138] Function: Chromium oxide in chromite has excellent high temperature resistance, oxidation resistance and corrosion resistance, and is particularly suitable for applications under extreme temperature conditions, such as furnace linings in the metallurgical industry.

[0139] Content requirement: Chromite content is required to be ≥98% to ensure its excellent refractory properties.

[0140] 5. Reinforced Fiber

[0141] type:

[0142] Alumina fiber: It has good high temperature stability and thermal insulation properties, and is used to improve the crack resistance and mechanical strength of the brick.

[0143] Silica fiber: Mainly used to enhance the high temperature resistance and chemical corrosion resistance of bricks, suitable for applications in complex environments.

[0144] Carbon fiber: has extremely high strength and heat resistance and is often used in refractory materials that require additional mechanical reinforcement.

[0145] Function: The reinforcing fibers are embedded in the brick body to form a skeleton structure, which enhances the tensile strength, crack resistance and impact resistance of the brick body.

[0146] 6. Nanomaterials

[0147] type:

[0148] Nano-alumina: can further improve the strength and thermal stability of refractory materials.

[0149] Nano-silicon oxide: helps improve the thermal insulation and crack resistance of the material.

[0150] Function: Nanomaterials improve the overall performance of bricks by filling pores and strengthening structures at a microscopic scale.

[0151] 7. Foaming agent

[0152] type:

[0153] Sodium bicarbonate (NaHCO3): Decomposes to produce carbon dioxide when heated, forming a microporous structure, which is used to lightweight insulation bricks and improve thermal insulation performance.

[0154] Borates: Often used to improve the stability of the foaming process and produce a uniform pore structure.

[0155] Phenolic resin: decomposes at high temperatures to form bubbles, further improving the thermal insulation of the brick.

[0156] Function: The foaming agent introduces a microporous structure during the brick forming process. These pores reduce the thermal conductivity of the brick, thereby improving its thermal insulation performance.

[0157] 8. Adhesive

[0158] type:

[0159] Phosphate binder: used to enhance the mechanical strength and chemical corrosion resistance of bricks.

[0160] Silicate Binder: Forms a refractory bond at high temperatures, providing additional structural stability.

[0161] Function: Binders provide consistency and strength to the mixture during the molding and firing process, ensuring the stability and durability of the final product.

[0162] 9. Surface treatment materials

[0163] Carburizing atmosphere: composed of carbon-containing gases (such as carbon monoxide or methane), used for carburizing the surface of bricks to enhance hardness and corrosion resistance.

[0164] Nitrogen atmosphere: used in the nitriding treatment of the brick surface to improve the surface wear resistance and oxidation resistance of the brick.

[0165] 10. Coating materials

[0166] Zirconium silicate coating: used to prevent brick corrosion in acidic environments and provide additional protection.

[0167] Aluminum silicate coating: used to enhance the chemical stability of bricks at high temperatures.

[0168] Titanium oxide coating: reduces heat conduction and improves thermal insulation performance by reflecting thermal radiation.

[0169] The following is an introduction in conjunction with specific embodiments:

[0170] Example 1: High temperature metallurgical furnace lining brick

[0171] Refractory raw materials: alumina (Al2O3, content ≥95%), magnesia (MgO, content ≥98%).

[0172] Reinforcement material: Alumina fiber, fiber diameter 3 microns, length 5 mm.

[0173] Foaming agent: sodium bicarbonate (NaHCO3, used in an amount of 4% by weight).

[0174] Surface treatment: Surface carburizing treatment, the temperature is controlled at 1000℃, the time is 3 hours.

[0175] Surface coating: aluminum silicate coating, secondary firing temperature is 1300℃.

[0176] Features: Suitable for lining of high temperature metallurgical furnaces, with extremely high refractoriness, chemical corrosion resistance and good mechanical strength.

[0177] Example 2: Anticorrosion and thermal insulation bricks for chemical equipment

[0178] Refractory raw materials: silicon oxide (SiO2, content ≥98%), a small amount of chromite (Cr2O3, content ≥2%).

[0179] Reinforcement material: silica fiber, fiber diameter 2 microns, length 8 mm.

[0180] Blowing agent: phenolic resin, used in an amount of 5% by weight.

[0181] Surface treatment: Surface nitriding treatment, temperature controlled at 900℃, time for 5 hours.

[0182] Surface coating: zirconium silicate coating, secondary firing temperature is 1400℃.

[0183] Features: Used for anti-corrosion and heat insulation of chemical equipment, it has excellent acid resistance and wear resistance, and can effectively insulate and prevent chemical corrosion.

[0184] Example 3: High temperature furnace roof insulation bricks

[0185] Refractory raw materials: alumina (Al2O3, content ≥97%), silicon oxide (SiO2, content ≥98%).

[0186] Reinforcement material: carbon fiber, fiber diameter 1 micron, length 10 mm.

[0187] Blowing agent: borate, used in an amount of 3% by weight.

[0188] Surface treatment: double treatment of surface carburizing and nitriding, carried out at 1000℃ and 850℃ respectively, each treatment time is 2 hours.

[0189] Surface coating: titanium oxide coating, secondary firing temperature is 1500℃.

[0190] Features: Used for heat insulation of high-temperature furnace roofs, it has excellent heat insulation performance and heat radiation reflection ability, as well as high strength and durability.

[0191] Example 4: Lightweight high temperature insulation brick

[0192] Refractory raw materials: silicon oxide (SiO2, content ≥95%), aluminum oxide (Al2O3, content ≥95%).

[0193] Reinforcement material: A small amount of nano-alumina, with a particle diameter of 50 nanometers, enhances the overall strength and thermal insulation performance of the brick.

[0194] Foaming agent: a combination of sodium bicarbonate and borate, used in amounts of 3 wt % and 2 wt % respectively.

[0195] Surface treatment: Surface carburizing treatment, the temperature is controlled at 1050℃, the time is 4 hours.

[0196] Surface coating: No additional coating treatment to reduce weight.

[0197] Features: Lightweight design is suitable for high-temperature equipment that needs to reduce structural burden, with good thermal insulation performance and heat resistance stability.

[0198] Example 5: Refractory bricks under high mechanical stress

[0199] Refractory raw materials: magnesia (MgO, content ≥98%), chromite (Cr2O3, content ≥98%).

[0200] Reinforcement material: Stainless steel skeleton reinforcement, steel wire diameter 0.5 mm, forming a built-in metal skeleton structure.

[0201] Blowing agent: phenolic resin, used in an amount of 4% by weight.

[0202] Surface treatment: Surface nitriding treatment, temperature controlled at 950℃, time for 3 hours.

[0203] Surface coating: zirconium silicate coating, secondary firing temperature is 1400℃.

[0204] Features: Designed for high mechanical stress environments, such as high pressure furnace linings in the metallurgical industry, with excellent impact resistance and corrosion resistance.

[0205] The following table 1 is the test data of various properties of refractory bricks

[0206] Table 1 Comparison of properties of refractory bricks in different embodiments

[0207]

[0208] Among them, the table fields are explained as follows:

[0209] 1. Refractoriness

[0210] Definition: Refractoriness refers to the ability of a material to maintain physical and chemical stability in a high temperature environment, usually expressed in degrees Celsius (℃).

[0211] Significance: The higher the refractoriness, the longer the service life of the brick under high temperature conditions, and the higher the ultimate temperature it can withstand. This is one of the most important properties of refractory bricks, especially when used in high temperature industries such as metallurgy, ceramics, and glass.

[0212] 2. Compressive strength

[0213] Definition: Compressive strength refers to the ability of a material to resist damage under compressive conditions, usually measured in megapascals (MPa).

[0214] Significance: Compressive strength determines the stability of the brick when subjected to mechanical stress. Higher compressive strength means that the brick is not easy to break or deform when subjected to heavy pressure or mechanical impact in a high temperature environment, and is suitable for furnace structures that bear heavy objects.

[0215] 3. Thermal insulation performance

[0216] Definition: Thermal insulation performance is usually expressed in terms of thermal conductivity (W / m·K), which describes the material's ability to conduct heat. The lower the value, the better the thermal insulation effect.

[0217] Significance: Good thermal insulation can reduce heat loss, improve energy efficiency, and protect the external structure from overheating. It is suitable for application scenarios where the high-temperature internal environment needs to be isolated from the outside world, such as the shell of a high-temperature furnace.

[0218] 4. Chemical resistance

[0219] Definition: Chemical resistance describes the ability of a material to resist corrosion by chemical substances (such as acids, alkalis, slag, etc.).

[0220] Significance: In the chemical industry or in metallurgical furnace linings, refractory bricks are often exposed to corrosive substances. Bricks with high chemical corrosion resistance can extend service life and maintain structural integrity, thereby reducing maintenance costs and downtime.

[0221] 5. Weight

[0222] Definition: Weight is usually expressed in terms of mass per cubic meter (kg / m 3 ) refers to the mass of material per unit volume.

[0223] Significance: Weight affects the construction difficulty and structural load of bricks. Lighter bricks are suitable for occasions where the overall structural weight needs to be reduced, while heavier bricks usually have higher density and strength and are suitable for more stringent use environments.

[0224] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Refractory insulation bricks with improved structure, characterized in that: include: Outer layer: directly exposed to high temperature and mechanical stress, covering the entire surface of the brick, providing initial protection and fire resistance; Porous insulation layer: Located on the inner side of the outer layer, this layer has a lower density and is full of tiny pores; Fiber grid reinforcement structure: embedded inside the porous insulation layer to form the internal skeleton of the brick body, and the fiber grid is distributed in the insulation layer; Surface hardened layer: located on the surface of the outer layer, a hardened layer formed by surface treatment; Anti-corrosion coating: The outermost coating layer covering the outer layer and the surface hardening layer.

2. A method for manufacturing a refractory heat-insulating brick with an improved structure, wherein the refractory heat-insulating brick with an improved structure according to claim 1 is characterized in that: The following steps are involved: S1. Raw material preparation Refractory raw material combination selection: including alumina, silica, magnesia and chromite; Reinforcement fiber: choose alumina fiber, silica fiber or carbon fiber; Nanomaterials: Choose nano-alumina or nano-silicon oxide; Foaming agent: choose sodium bicarbonate, borate or phenolic resin; S2. Mixing and pulping mix: Mix the refractory raw materials selected in step S1 according to weight ratio, and add a binder after mixing evenly; Grinding: Grind the mixed slurry by ball mill or stirring mill and control the grinding time; S3, Forming Use metal molds or silicone molds, and choose semi-dry molding, slip casting or isostatic pressing; S4. Drying The formed materials are dried naturally, heated or microwaved; S5, Firing Heating stage: Firing in a high-temperature kiln, controlling the heating rate; Holding stage: After reaching the target firing temperature, the holding time is set according to the thickness and size of the blank; Cooling stage: natural cooling or slow cooling is adopted, and the cooling rate is controlled until the blank is cooled to room temperature; S6, surface hardening Surface carburizing: Place the fired brick body in a carbon-containing atmosphere for carburizing treatment, and control the temperature and time; Surface nitriding: Treat the brick surface in a high-temperature nitrogen atmosphere and control the temperature and time.

3. The method for manufacturing refractory insulation bricks with improved structure according to claim 2, characterized in that: In the step S1, the content of aluminum oxide is ≥95%, the content of silicon oxide is ≥98%, the content of magnesia is ≥95%, the content of chromite is ≥98%, the fiber diameter is between 1-5 microns, the length is 1-10 mm, the diameter of the nano material particles is between 10-100 nanometers, and the amount of sodium bicarbonate used is 3-5% by weight.

4. The method for manufacturing refractory insulation bricks with improved structure according to claim 2, characterized in that: In the step S2, the refractory raw materials are mixed according to 70%-90% of the matrix material and 10%-30% of the reinforcing material or the foaming agent. The binder includes a phosphate binder and a silicate binder, and the addition amount is 5%-10%. The grinding time is controlled within 2-4 hours until the particle fineness reaches 200-400 meshes.

5. The method for manufacturing refractory insulation bricks with improved structure according to claim 2, characterized in that: In the step S3; Semi-dry molding: put the slurry with a water content of 5%-10% into the mold and apply a pressure of 20-50MPa to mold; Grouting: The slurry is injected into the mold and solidified by natural drying or heating drying. Isostatic pressing: Wrap the slurry in a rubber sleeve, place it in an isostatic pressing device, and apply a pressure of 100-200MPa.

6. The method for manufacturing refractory insulation bricks with improved structure according to claim 2, characterized in that: In the step S4; Natural drying: Place the blank at room temperature for 24-48 hours to allow its moisture to evaporate naturally; Heating and drying: Dry in an oven at 60-110℃ for 8-12 hours to accelerate the evaporation of water; Microwave drying: Using microwave drying equipment, the temperature is controlled at 70-100℃ and the drying time is 2-4 hours.

7. The method for manufacturing refractory insulation bricks with improved structure according to claim 2, characterized in that: In the step S5, the heating rate is controlled at 5-10°C / min, and the holding time is 2-4 hours; The firing temperature range is as follows: Alumina based bricks: 1500-1600℃ Silica based bricks: 1400-1500℃ Magnesia based brick: 1600-1700℃ Chromite-based bricks: 1600-1700℃ The cooling rate is controlled at 5-10°C / min until the blank is cooled to room temperature.

8. The method for manufacturing refractory insulation bricks with improved structure according to claim 2, characterized in that: In the step S6, the temperature of the surface carburizing is controlled at 900-1100° C. for 2-4 hours, and the temperature of the surface nitriding is controlled at 800-1000° C. for 4-6 hours.

9. The method for manufacturing refractory insulation bricks with improved structure according to claim 2, characterized in that: After the step S3, skeleton enhancement is performed; Fiber mesh embedding: During the molding process, an alumina fiber mesh or a carbon fiber mesh is embedded in the slurry to form the internal skeleton structure of the brick body; Metal skeleton reinforcement: Stainless steel or high temperature resistant alloy wire mesh or skeleton is embedded during the forming process.

10. The method for manufacturing refractory insulation bricks with improved structure according to claim 2, characterized in that: After the step S6, surface coating is performed; Anti-corrosion coating: A layer of acid-resistant or alkali-resistant coating, including zirconium silicate and aluminum silicate coating, is applied to the surface of the brick, and then a secondary firing is performed, and the temperature is controlled at 1200-1400℃; Reflective coating: Titanium oxide coating is applied on the surface of the brick.

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