A light and high-strength layered refractory material and a preparation method thereof

Abstract

The present invention discloses a light and high-strength layered refractory material and a preparation method thereof, and belongs to the technical field of refractory materials. The refractory material is composed of several layers of thin layer units with different porosities and different thicknesses, and the thin layer units are one or both of a dense layer and a porous layer. The preparation method of the refractory material comprises the preparation of a dense layer slurry, the preparation of a porous layer slurry, and pouring the slurry layer by layer according to the structural composition of the refractory material. After the gelation reaction is completed, the green body is dried and sintered to obtain a light and high-strength layered refractory material. The refractory material of the present invention is prepared by gel casting technology, which is simple and efficient to operate, can realize large-scale production of layered refractory materials with specific needs, and is convenient for promotion and application. At the same time, the density of the refractory material prepared by the present invention is 0.32-1.23 g / cm 2 , with a strength of 10‑87 MPa, and is used as an integrated composite refractory material for the thermal insulation lining and working lining of industrial furnaces.

Description

Technical Field

[0001] The invention discloses a light and high-strength layered refractory material and a preparation method thereof, and belongs to the technical field of refractory materials. Background Art

[0002] Under the guidance of the current "carbon peak and carbon neutrality" goals, local governments and departments are increasingly concerned about the energy consumption level and carbon emissions per unit output, among which industrial energy consumption and carbon emissions account for the largest proportion. Technological progress and energy conservation and emission reduction in high-temperature industries are also receiving more and more attention. Among them, industrial kilns are the main energy-consuming equipment in the high-temperature industrial field, consuming huge amounts of energy every year. Especially in the thermal processing projects of metallurgical, building materials, ceramics, glass, chemical and electromechanical enterprises, the energy consumption of industrial kilns can account for 40% to 70% of the total energy consumption. However, the heat loss of various industrial kilns is generally large, and in most cases, its energy utilization rate is less than 30%. The most important measure for energy saving of industrial kilns is to select materials with better quality and better thermal insulation performance, which can significantly reduce the heat loss of the kiln body, ensure the stability of the temperature and atmosphere in the kiln, improve the thermal efficiency of high-temperature industrial thermal equipment, and reduce energy consumption.

[0003] In the traditional commonly used thermal insulation materials, there are still common problems such as high thermal conductivity, easy powdering and shrinkage of fiber-type thermal insulation materials, and the thermal insulation performance needs to be further improved. In order to break through the bottleneck of traditional thermal insulation materials, realize universal application and upgrade of traditional thermal insulation materials, it is particularly important to develop a new type of multi-layer refractory material that integrates thermal insulation lining and working lining, has different functions of each layer unit, and has the advantages of low thermal conductivity, good volume stability and thermal shock resistance.

[0004] Application No. 2019100296056 discloses a method for preparing a layered corundum-spinel refractory material, using liquid ceramic precursor polynitrogen silane as a skeleton material, aluminum sec-butoxide as a doping Al source, divinyl toluene to increase the number of carbon-carbon double bonds, and cyclohexane as a solvent to prepare a SiAlCN ceramic precursor; SiAlCN ceramic precursor, composite binder and Ni(NO 3 ) 2 6H 2 O and Al 2 O 3 The powders are mixed to obtain a mixture, which is then cold-pressed to obtain an alumina blank; tape-casting is used to prepare a spinel thin blank; and hot-pressing is used to laminate the spinel thin blanks and the alumina blanks alternately to prepare a multi-layer corundum-spinel blank. This method is relatively complicated to operate in preparing layered refractory materials, involves more organic reagents, and cannot achieve integration of the new thermal insulation lining and the working lining. Summary of the invention

[0005] In order to break through the bottleneck of traditional thermal insulation materials and realize universal application and upgrading of traditional thermal insulation materials, the present invention takes changing the traditional structure of the material to realize a layered refractory material with smaller volume and better energy-saving and thermal insulation performance as the research goal, and provides a lightweight and high-strength layered refractory material and a preparation method thereof. The prepared refractory material is a multi-layered thermal insulation material with many advantages such as lower thermal conductivity and expansion coefficient, good volume stability and thermal shock resistance.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A light and high-strength layered refractory material, the refractory material is composed of several thin layer units with different porosities and different thicknesses, wherein the thin layer units are one or both of dense layers and porous layers. For example, the refractory material can be composed of several layers of different porous layers, or of different types of dense layers, or of different types of dense layers and porous layers.

[0008] Furthermore, the porosity of the porous layer is 20-90%.

[0009] Furthermore, the thickness of the thin layer unit is 1-30 mm, and the thickness of the refractory material is 20-60 mm.

[0010] A method for preparing a lightweight and high-strength layered refractory material comprises the following steps:

[0011] Step 1: Preparation of dense layer slurry

[0012] One or more of amino acid derivatives, polysaccharides and their derivatives are used as a gel system, dissolved in water, and heat-insulating and high-temperature resistant powder is added to prepare a dense layer slurry;

[0013] Step 2: Preparation of pore layer slurry

[0014] One or more of amino acid derivatives, polysaccharides and their derivatives are used as gel systems, dissolved in water, heat-insulating and high-temperature-resistant powders are added, and then additives are added to prepare pore layer slurry, wherein the additive is one of a pore former, a foaming agent, a template, and an emulsifier;

[0015] Step three: pour layer by layer according to the structural composition of the refractory material. After the gelation reaction is completed, place the green body in a drying oven at 60-120°C for 4-24 hours, then heat the temperature to 800-1500°C at a heating rate of 3-5°C / min and sinter for 1-4 hours to obtain a lightweight and high-strength layered refractory material.

[0016] Furthermore, the heat-insulating and high-temperature-resistant powder is one or more of silica, mullite, corundum, clay, magnesia-aluminum spinel, and dolomite.

[0017] Furthermore, the amino acid derivative is one of polyaspartic acid, polylysine and polyglutamic acid.

[0018] Furthermore, the polysaccharide and its derivatives are one of sucrose, agarose and glucose.

[0019] Furthermore, the pore-forming agent is one of hollow fly ash balls, starch, sawdust, and graphite; the foaming agent is one of sodium dodecyl sulfate, quaternary ammonium salt, azobisisobutyronitrile, and organic peroxide; the template is one of sponge, loofah, and wood, with a thickness of 1-30 mm; the emulsifier is one of stearate, 1,4-polydimethylsiloxane, and glycerol oleate.

[0020] Furthermore, in the step 1, the mass ratio of the gel system: water: heat-insulating and high-temperature resistant powder in the dense layer slurry is 1-5:10-20:75-89.

[0021] Furthermore, in the step 2, the mass ratio of the gel system: water: heat-insulating and high-temperature-resistant powder: additive in the porous layer slurry is 1-5:10-20:50-88:1-25.

[0022] Furthermore, the density of the refractory material prepared by the preparation method is 0.32-1.23 g / cm 2 , with a strength of 10-87MPa, and is used as an integrated composite refractory material for the thermal insulation lining and working lining of industrial furnaces.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention is based on the principle of in-situ polymerization and consolidation of ceramic powders in a gel casting system, which can not only obtain a ceramic body with high strength and controllable porosity; at the same time, it can stack and consolidate the layers within the time range after the polymerization of each thin layer unit and before it is completely dried, thereby realizing the preparation of a lightweight and high-strength layered refractory material.

[0025] 2. The lightweight and high-strength layered refractory material of the present invention can realize the integration of the heat insulation lining and the working lining of the industrial kiln, and has the advantages of low thermal conductivity, good volume stability and thermal shock resistance.

[0026] 3. The present invention adopts gel casting technology for preparation, which is simple and efficient to operate, can realize large-scale production of layered refractory materials with specific needs, and is easy to promote and apply. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of the lightweight and high-strength layered refractory material of the present invention;

[0028] Figure 2 This is a SEM image of the lightweight and high-strength layered refractory material of the present invention. Implementation

[0029] The technical solution and effects of the present invention are further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto. Example

[0030] The structure of the refractory material of this embodiment is composed of four 3 mm dense layers and four 10 mm pore layers interlaced with each other.

[0031] The preparation method of the lightweight and high-strength layered refractory material of this embodiment is:

[0032] Step 1: Preparation of dense layer slurry

[0033] Polyglutamic acid was used as the gel system, dissolved in water, and corundum was added in a mass ratio of 1:10:89 to prepare a dense layer slurry;

[0034] Step 2: Preparation of pore layer slurry

[0035] Polyglutamic acid was used as the gel system, dissolved in water, corundum was added, and then fly ash hollow balls were added as pore-forming agents, with a mass ratio of 2:10:63:25 to prepare the pore layer slurry with a porosity of 67%;

[0036] Step three: pour the dense layer slurry into the mold with a thickness of 3 mm, and pour the porous layer slurry with a thickness of 10 mm after gelation; repeat the pouring process 4 times to obtain a green body with a total thickness of 52 mm.

[0037] After the green body was gelled, it was placed in a drying oven at 60 °C for 12 h, and then heated to 1000 °C at a heating rate of 5 °C / min and sintered for 2 h to obtain a sample with a porosity of 55% and an overall density of 1.08 g / cm 2 , the strength perpendicular to the stacking direction is 27 MPa, the thermal conductivity is 0.481 W / m·k, and the thermal expansion coefficient is 5.3×10 -6 ℃, the flexural strength retention rate after thermal shock is 68.7%; the strength parallel to the stacking direction is 82 MPa, the thermal conductivity is 0.825 W / m·k, and the thermal expansion coefficient is 4.5×10 -6 ℃, and the flexural strength retention rate after thermal shock is 80.6%. Example

[0038] The structure of the refractory material of this embodiment is composed of three 7 mm dense layers and two 10 mm pore layers interlaced with each other.

[0039] The preparation method of the lightweight and high-strength layered refractory material of this embodiment is:

[0040] Step 1: Preparation of dense layer slurry

[0041] Polyglutamic acid was used as the gel system, dissolved in water, and corundum was added in a mass ratio of 2:15:83 to prepare a dense layer slurry;

[0042] Step 2: Preparation of pore layer slurry

[0043] Agarose was used as the gel system, dissolved in water, mullite was added, and then sodium dodecyl sulfate foaming agent was added in a mass ratio of 1:10:87:2 to prepare a porous layer slurry with a porosity of 85%;

[0044] Step three, pour the dense layer slurry into the mold with a thickness of 7 mm, and pour the porous layer slurry with a thickness of 10 mm after gelation; repeat the pouring process twice, and then pour the dense layer slurry into the mold with a thickness of 7 mm, to obtain a green body with a total thickness of 41 mm.

[0045] After the green body was gelled, it was placed in a drying oven at 70 °C for 6 hours, and then heated to 1300 °C at a heating rate of 5 °C / min and sintered for 1 h to obtain a sample with a porosity of 73% and an overall density of 0.53 g / cm 2 , the strength perpendicular to the stacking direction is 15 MPa, the thermal conductivity is 0.357 W / m·k, and the thermal expansion coefficient is 5.0×10 -6 ℃, the flexural strength retention rate after thermal shock is 70.2%; the strength parallel to the stacking direction is 63 MPa, the thermal conductivity is 0.682 W / m·k, and the thermal expansion coefficient is 5.3×10 -6 ℃, and the flexural strength retention rate after thermal shock is 65.3%. Example

[0046] The structure of the refractory material of this embodiment consists of a 10 mm pore layer and a 20 mm sponge pore layer.

[0047] The preparation method of the lightweight and high-strength layered refractory material of this embodiment is:

[0048] Step 1: Preparation of pore layer slurry

[0049] Sucrose was used as the gel system, dissolved in water, magnesium aluminum spinel was added, and starch was added as a pore-forming agent, and the mass ratio was 1:15:64:20 to prepare a pore layer slurry with a porosity of 52%;

[0050] Agarose was used as the gel system, dissolved in water, and mullite was added at a mass ratio of 5:20:75. After thorough mixing, a 20 mm thick sponge was completely immersed, and the porosity was 88%;

[0051] Step 2: pour the slurry of the porous layer into the mold with a thickness of 10 mm, and put the sponge soaked in the slurry into the mold after gelation to obtain a green body with a total thickness of 30 mm.

[0052] After the green body was gelled, it was placed in a drying oven at 100 °C for 6 h, and then heated to 900 °C at a heating rate of 3 °C / min for 4 h to obtain a sample with a porosity of 80% and an overall density of 0.32 g / cm 2 , the strength perpendicular to the stacking direction is 12 MPa, the thermal conductivity is 0.181 W / m·k, and the thermal expansion coefficient is 11×10 -6 ℃, the flexural strength retention rate after thermal shock is 58.3%; the strength parallel to the stacking direction is 19 MPa, the thermal conductivity is 0.425 W / m·k, and the thermal expansion coefficient is 10×10 -6 ℃, and the flexural strength retention rate after thermal shock was 62.8%.

[0053] The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art without departing from the principle of the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A lightweight, high-strength layered refractory material for integrating the heat insulation lining and working lining of industrial furnaces in the high-temperature industrial field, characterized in that: The overall density of the refractory material is 1.08 g / cm 2 , the strength perpendicular to the stacking direction is 27 MPa, the thermal conductivity is 0.481 W / m·k, and the thermal expansion coefficient is 5.3×10 -6 ℃, the flexural strength retention rate after thermal shock is 68.7%; The strength parallel to the stacking direction is 82 MPa, the thermal conductivity is 0.825 W / m·k, and the thermal expansion coefficient is 4.5×10 -6 ℃, the flexural strength retention rate after thermal shock is 80.6%; The preparation method of the lightweight and high-strength layered refractory material is as follows: Step 1: Preparation of dense layer slurry Polyglutamic acid was used as the gel system, dissolved in water, and corundum was added in a mass ratio of 1:10:89 to prepare a dense layer slurry; Step 2: Preparation of pore layer slurry Polyglutamic acid was used as the gel system, dissolved in water, corundum was added, and then fly ash hollow balls were added as pore-forming agents, with a mass ratio of 2:10:63:25 to prepare the pore layer slurry with a porosity of 67%; Step 3: Pour the dense layer slurry into the mold with a thickness of 3 mm, and pour the porous layer slurry with a thickness of 10 mm after gelation; repeat the pouring process 4 times to obtain a green body with a total thickness of 52 mm; After the green body was gelled, it was placed in a drying oven at 60°C for 12 hours, and then sintered at 1000°C at a heating rate of 5°C / min for 2 hours to obtain a sample with a porosity of 55%.

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