Composite, insulating cover sheet and method

Abstract

The application discloses a kind of composite, heat-insulating cover plate and method.The composite for improving the heat-insulating performance of heat-insulating cover plate of the application includes the following components: SiO2 micro powder 50-70 parts, alpha-Al2O3 micro powder 5-15 parts, mullite refractory fiber 25-40 parts, complex binder of carboxymethyl cellulose 10-15 parts and water 180-550 parts.The composite of the application can be used to form heat-insulating cover plate, and the heat-insulating performance of the obtained heat-insulating cover plate is better, and the bulk density is smaller.

Description

Technical Field

[0001] This invention relates to a composite material, an insulating cover plate, and a method thereof. Background Technology

[0002] As the requirements for the insulation effect of special steel mold risers continue to increase, the materials used for insulation at the top of the risers are also changing.

[0003] Previously, it was covered with traditional loose powder, anti-shrinkage agent, heating agent, carbonized rice husk, etc., but this caused dust pollution problems.

[0004] To avoid dust pollution from the aforementioned bulk powder materials, hollow insulation covers have emerged in recent years. While these covers have solved the on-site environmental pollution problem, their insulation effect is not significant, and they suffer from high bulk density, heavy individual unit weight, inconvenience for on-site operators, and high labor intensity, making them unsuitable for widespread application. Furthermore, hollow insulation covers rely on hollow air to reduce thermal conductivity; however, in actual use, this often results in the hollow layer being corroded by high-temperature molten steel, damaging the insulation and causing it to lose its insulating properties.

[0005] CN214392258U discloses a riser and a casting mold. The riser includes a riser body and a heat insulation device. The heat insulation device includes an inner heat insulation layer and a cover plate. The inner heat insulation layer is disposed along the inner wall of the riser, and its shape is configured to match the shape of the inner wall of the riser. The cover plate is disposed above the inner heat insulation layer and includes a heat insulation layer and a second vacuum chamber. The second vacuum chamber is disposed in the heat insulation layer and is filled with aerogel. The structure of this cover plate is relatively complex, making it somewhat difficult to manufacture. Moreover, it also suffers from the problem of hollow heat insulation cover plates being corroded by high-temperature molten steel, which damages the vacuum chamber and causes it to lose its heat insulation function.

[0006] CN112916793A discloses a lightweight thermal insulation coating material for selective laser sintering and its preparation method. This lightweight thermal insulation coating material comprises fly ash cenospheres, a composite binder, a coupling agent, a curing agent, and a lubricant. The composite binder is composed of fast-polymerizing medium-strength phenolic resin and slow-polymerizing high-strength phenolic resin; the coupling agent is silane coupling agent HK550; the curing agent is hexamethylenetetramine; and the lubricant is calcium stearate. This lightweight thermal insulation coating material can be used to print irregularly shaped casting thermal insulation risers. Its bulk density and thermal conductivity still need further reduction, and its heating linear change rate is still relatively high.

[0007] CN1590347A discloses an aluminosilicate refractory fiberboard, which is composed of aluminosilicate refractory fibers, an organic binder, an inorganic binder, and additives. The organic binder is cationic starch, sodium carboxymethyl cellulose, and polyvinyl alcohol, or any two or one of these. The inorganic binder is silica sol or other inorganic binders with silicon as the main element and alumina sol, or any one of these. The additive is fine or micro-alumina powder. Although this refractory fiberboard can withstand high temperatures, its bulk density still needs to be reduced, and its thermal shrinkage rate needs to be improved. Summary of the Invention

[0008] One object of the present invention is to provide a composite material for improving the thermal insulation performance of an insulating cover plate, the composite material having a low thermal conductivity. Another object of the present invention is to provide a method for preparing the composite material as described above. Yet another object of the present invention is to provide an insulating cover plate having a low thermal conductivity, low bulk density, and low rate of change of heating linearity. A further object of the present invention is to provide a method for producing the insulating cover plate as described above.

[0009] On one hand, the present invention provides a composite material for improving the thermal insulation performance of a thermal insulation cover plate, comprising the following components:

[0010] 50-70 parts SiO2 micro powder, 5-15 parts α-Al2O3 micro powder, 25-40 parts mullite refractory fiber, 10-15 parts carboxymethyl cellulose composite binder, and 180-550 parts water.

[0011] According to the composite of the present invention, preferably, the SiO2 micro powder has a particle size of 0.1–0.5 μm and a specific surface area of ​​15–30 m². 2 / g; The SiO2 content in the SiO2 micro powder is 87-98wt%.

[0012] According to the composite of the present invention, preferably, the particle size of the α-Al2O3 micro powder is 0.3 to 0.6 μm; and the content of Al2O3 in the α-Al2O3 micro powder is ≤99 wt%.

[0013] According to the composite of the present invention, preferably, the mullite refractory fiber has a refractory temperature ≥1500℃ and a diameter of 3~5μm.

[0014] The composite according to the present invention is preferably composed of only the following components:

[0015] 50-70 parts SiO2 micro powder, 5-15 parts α-Al2O3 micro powder, 25-40 parts mullite refractory fiber, 10-15 parts carboxymethyl cellulose composite binder, and 180-550 parts water.

[0016] On the other hand, the present invention also provides a method for preparing the complex according to the above description, comprising the following steps:

[0017] A premix of SiO2 micro powder, α-Al2O3 micro powder, mullite refractory fiber and carboxymethyl cellulose binder was obtained; the premix was then mixed with water and stirred to obtain a composite material.

[0018] According to the preparation method of the present invention, preferably, the premix is ​​mixed with water and stirred in a pulper for 10-20 minutes to obtain the composite.

[0019] In another aspect, the present invention also provides a heat-insulating cover plate, comprising the following components:

[0020] The complex described above (on a dry weight basis) is present in quantities of 250–350 parts.

[0021] 100-150 parts silica sand

[0022] Combine with 25-35 parts of clay-diatomaceous earth.

[0023] 10-15 parts of modified phenolic resin,

[0024] 20-30 parts organic fiber

[0025] 5-10 parts of blue-pinai mineral powder;

[0026] The mass ratio of clay to diatomaceous earth is 1:1.

[0027] According to the thermal insulation cover plate of the present invention, preferably, the content of SiO2 in the silica sand is ≤99wt%, and the particle size is ≥90% passing through a 200-mesh sieve; the organic fiber is a fiber formed from at least one of wheat straw, corn stalks, reed stalks, and rice straw.

[0028] Furthermore, the present invention also provides a method for producing the thermal insulation cover plate as described above, comprising the following steps:

[0029] 1) According to the corresponding weight parts, the above-mentioned composite, silica sand, bonded clay-diatomaceous earth, modified phenolic resin, organic fiber, and blue pebbly mineral powder are mixed to obtain a mixture;

[0030] 2) Place the mixture into a mold and perform vacuum filtration to obtain the insulation cover plate blank;

[0031] 3) Dry the insulation cover plate blank to obtain the insulation cover plate.

[0032] The composite of this invention has low thermal conductivity and high temperature resistance. The insulating cover plate of this invention has good thermal insulation performance, low bulk density, is lightweight, and easy to handle. The production method of the insulating cover plate of this invention is simple and easy to promote and apply. Currently, there are no reports of using this composite plate in the manufacture of insulating cover plates for special steel mold risers. Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0034] In this invention, unless otherwise specified, "parts" refers to parts by weight. For example, 50 to 70 parts means 50 to 70 parts by weight.

[0035] <Complex and its preparation method>

[0036] This invention provides a composite material for improving the thermal insulation performance of thermal insulation covers.

[0037] The composite of the present invention comprises the following components: 50-70 parts of SiO2 micro powder, 5-15 parts of α-Al2O3 micro powder, 25-40 parts of mullite refractory fiber, 10-15 parts of carboxymethyl cellulose composite binder, and 180-550 parts of water.

[0038] In the composite of this invention, the weight percentage of SiO2 micro powder is greater than that of α-Al2O3 micro powder, and also greater than that of mullite refractory fiber. This invention reveals that the weight ratio of these three components in the composite is crucial, affecting the performance of the composite and consequently the performance of the insulation cover.

[0039] The preferred amount of SiO2 micro powder is 55-65 parts, more preferably 55-60 parts. The preferred amount of α-Al2O3 micro powder is 8-15 parts, more preferably 10-12 parts. The preferred amount of mullite refractory fiber is 25-35 parts, more preferably 25-30 parts.

[0040] In this invention, the particle size of the SiO2 micro powder is 0.1–0.5 μm, preferably 0.1–0.4 μm, and more preferably 0.2–0.4 μm; the specific surface area is 15–30 m². 2 / g, preferably 18-28m 2 / g, more preferably 20-25m 2 / g; The SiO2 content in the SiO2 micro powder is 87-98wt%, preferably 90-95wt%.

[0041] The particle size of the α-Al₂O₃ micro powder is 0.3–0.6 μm, preferably 0.4–0.6 μm, and more preferably 0.4–0.5 μm. The Al₂O₃ content in the α-Al₂O₃ micro powder is ≤99 wt%, preferably 95% ≤ the Al₂O₃ content ≤99 wt%.

[0042] Mullite refractory fibers have a refractory temperature ≥1500℃ and a diameter of 3~5μm.

[0043] The composite binder of carboxymethyl cellulose acts as an adhesive and thickener, and its source is not particularly restricted. For example, it can be a composite binder of carboxymethyl cellulose manufactured by Hebei Haoshuo Chemical Co., Ltd.

[0044] The composite binder of carboxymethyl cellulose is preferably 10 to 13 parts, more preferably 10 to 11 parts.

[0045] In the complex, the weight of water is approximately 2 to 5 times the sum of the weights of the other components, preferably 3 to 4 times.

[0046] According to a specific embodiment of the present invention, the composite of the present invention consists only of the following components: 50-70 parts of SiO2 micro powder, 5-15 parts of α-Al2O3 micro powder, 25-40 parts of mullite refractory fiber, 10-15 parts of carboxymethyl cellulose composite binder, and 180-550 parts of water.

[0047] The present invention also provides a method for preparing a composite for improving the thermal insulation performance of a thermal insulation cover plate, comprising the following steps: premixing a composite binder of SiO2 micro powder, α-Al2O3 micro powder, mullite refractory fiber and carboxymethyl cellulose to obtain a premix; mixing the premix with water and stirring to obtain a composite.

[0048] In this invention, the components are weighed and mixed according to the weights described above to obtain a premix. The premix is ​​then mixed with water and stirred in a pulper for 10–20 minutes to obtain a composite. This invention has found that mixing the premix with water and stirring it in a hydrapulper achieves a loosening effect, which is beneficial for producing thermal insulation covers with better thermal insulation performance and lower bulk density.

[0049] According to a specific embodiment of the present invention, a method for preparing a composite for improving the thermal insulation performance of a thermal insulation cover includes the following steps: premixing 50-70 parts of SiO2 micro powder, 5-15 parts of α-Al2O3 micro powder, 25-40 parts of mullite refractory fiber, and 10-15 parts of a carboxymethyl cellulose composite binder to obtain a premix; mixing the premix with 180-550 parts of water and stirring in a pulper for 10-20 minutes to obtain the composite.

[0050] <Insulated Cover Plate and Its Production Method>

[0051] This invention also provides a thermal insulation cover, particularly suitable for thermal insulation covers for risers in special steel molds. The thermal insulation cover comprises the following components: 250-300 parts of the composite material described above (by dry weight), 100-150 parts of silica sand, 25-35 parts of bound clay-diatomaceous earth, 10-15 parts of modified phenolic resin, 20-30 parts of organic fiber, and 5-10 parts of bluestone group mineral powder. Such a thermal insulation cover exhibits good thermal insulation performance, such as low thermal conductivity, low heating linear change rate, and low bulk density, making it easy to operate and use.

[0052] In this invention, the weight of the complex as described above, on a dry weight basis, refers to the sum of the weights of the other components excluding water.

[0053] The silica sand is high-silica sand. Silica sand is used as aggregate. Preferably, the silica sand content is 100-140 parts, more preferably 100-120 parts. The SiO2 content in the silica sand is ≤99wt%, and the particle size of the silica sand has a 200-mesh sieve passing rate ≥90%. Preferably, the SiO2 content is 95wt%≤99wt%. The binding clay-diatomaceous earth content is preferably 28-32 parts, more preferably 30-31 parts; wherein the mass ratio of binding clay to diatomaceous earth is 1:1. The modified phenolic resin is preferably 10-13 parts, more preferably 10-12 parts. The organic fiber is preferably 22-28 parts, more preferably 25-26 parts. The organic fiber is fiber formed from at least one of wheat straw, corn stalks, reed stalks, rice straw, etc. The rice straw is threshed rice straw. The organic fiber length is 5-15 mm. The blue quartz group mineral powder is preferably 5-8 parts, more preferably 5-7 parts.

[0054] There are no particular restrictions on the sources of silica sand, bonding clay-diatomaceous earth, modified phenolic resin, additives (i.e., bluestone group mineral powder), and organic fibers in the thermal insulation cover plate.

[0055] The present invention also provides a method for producing the thermal insulation cover plate as described above, comprising the following steps:

[0056] 1) According to the corresponding weight parts, the above-mentioned composite, silica sand, binding clay-diatomaceous earth, modified phenolic resin, organic fiber and additives are mixed to obtain a mixture;

[0057] 2) Place the mixture into a mold and perform vacuum filtration to obtain the insulation cover plate blank;

[0058] 3) Dry the insulation cover plate blank to obtain the insulation cover plate.

[0059] In this way, the resulting insulation cover is more durable and has a very low bulk density and low thermal conductivity.

[0060] In step 1), the required raw materials in corresponding parts by weight are mixed, and forced stirring and mixing can be carried out for 15 to 20 minutes to obtain a mixture.

[0061] In step 2), the mixture is weighed according to the amount required for the insulation cover plates of different specifications and spread into a mold (referring to the mold for producing insulation cover plates). Start vacuum suction filtration. The purpose is to filter out excess water through vacuum suction, and at the same time, it can make the product embryo generate vertically penetrating pores, increasing the porosity of the dried insulation cover plate. The vacuum pressure is not less than 0.5 MPa.

[0062] In step 3), the obtained insulation cover plate blank is placed on a special tray, put into a drying cart and placed in a drying kiln for drying. It is dried for 12 to 24 hours according to the specified heating requirements. It is only necessary to detect that the water content of the product is ≤ 6 wt%, and then it can be taken out of the kiln, packaged and stored in the warehouse. Specifically, after the insulation cover plate blank is put into the drying kiln, the temperature is slowly increased. It is heated to 100 - 110 °C in 1 - 1.5 hours, then continue to heat up, heated to 118 - 125 °C in 2 - 2.5 hours, continue to heat up, heated to 130 - 135 °C in 2 - 2.5 hours, continue to heat up, heated to 145 - 150 °C in 2 - 2.5 hours, and then keep it at 145 - 150 °C for 8 - 15 hours. Then cool down, take samples to detect and analyze the moisture content. If the water content is ≤ 6 wt%, it is qualified.

[0063] The drying time is preferably 15 - 24 hours, more preferably 18 - 20 hours. Preferably, it is detected that the water content of the product is ≤ 3 wt%, and more preferably the water content is ≤ 1 wt%, then the insulation cover plate is obtained.

[0064] The insulation cover plate produced by the present invention is resistant to high-temperature molten steel erosion, has overall heat preservation and thermal shock resistance and is not easy to crack; its thermal conductivity is low. The thermal conductivity at 800 °C is only 1 / 2 of that of the hollow insulation cover plate (with static air in the hollow structure) sold on the current market. Its bulk density is small, and its overall weight is only 2 / 3 of that of the hollow insulation cover plate of the same specification on the current market. It is convenient for on-site operators to operate and reduces labor intensity. The economic benefits are better.

[0065] The insulation cover plate of the present invention can be used for heat preservation of the riser of special steel molds, and can also be used for heat preservation of the non-working layer in the middle of the ladle. The thermal conductivity (800 °C) of the insulation cover plate of the present invention is less than 0.14 W / (m·k), preferably less than or equal to 0.13 W / (m·k), for example, it can be 0.12 W / (m·k); the heating wire change rate (1100 °C) is less than or equal to 5%; the bulk density is less than or equal to 0.55 g / cm 3 preferably less than or equal to 0.45 g / cm 3 for example, it can be 0.4 g / cm 3 .

[0066] <Raw material description>

[0067] The raw materials used in the following preparation examples and embodiments are described below:

[0068] The particle size of SiO2 micro powder is 0.1–0.15 μm, and the specific surface area is 15–27 m². 2 / g; The SiO2 content in the SiO2 micro powder is above 90wt%. The SiO2 micro powder was purchased from Gansu Sanyuan Silicon Materials Co., Ltd.

[0069] The particle size of the α-Al₂O₃ micro powder is 0.3–0.6 μm; the Al₂O₃ content in the α-Al₂O₃ micro powder is ≤99 wt%. The α-Al₂O₃ micro powder was purchased from Shandong Zibo Ruihe Building Materials Co., Ltd.

[0070] The mullite refractory fiber has a refractory temperature ≥1500℃ and a diameter of 3~5μm. The mullite refractory fiber was purchased from Zhejiang Deqing Hongye Crystal Fiber Co., Ltd.

[0071] The carboxymethyl cellulose composite binder is sourced from Hebei Haoshuo Chemical Co., Ltd.

[0072] The high-silica sand contains ≤99wt% SiO2 and has a particle size of ≥90% passing through a 200-mesh sieve. The high-silica sand was purchased from Haoyuan Silica Sand Co., Ltd. in Yinan County, Shandong Province.

[0073] The clay-diatomite mixture was purchased from Jilin Yuantong Mining Co., Ltd., with a mass ratio of 1:1 between the clay and diatomite.

[0074] Modified phenolic resin: sourced from Sanjiu Dextrin Factory in Liaoyang City, Liaoning Province.

[0075] Organic fiber is formed from wheat straw and rice straw. The organic fiber is processed by Baotou Yuanda Building Materials Co., Ltd. The process involves mixing wheat straw and rice straw in a 1:1 mass ratio and then processing them using a high-speed crusher and air separation. The length of the organic fiber is 5-15mm.

[0076] The blue quartz mineral powder was purchased from Guilin Mining Machinery Factory.

[0077] Preparation Example 1

[0078] 55 parts of SiO2 micro powder, 10 parts of α-Al2O3 micro powder, 25 parts of mullite refractory fiber and 10 parts of carboxymethyl cellulose composite binder were premixed to obtain a premix; the premix was mixed with 300 parts of water and stirred in a pulper for 15 minutes to obtain a composite material for improving the thermal insulation performance of the thermal insulation cover.

[0079] Example 1

[0080] 300 parts of the composite obtained in Preparation Example 1 (by dry weight), 100 parts of silica sand, 30 parts of bonded clay-diatomite, 10 parts of modified phenolic resin, 25 parts of organic fiber, and 5 parts of bluestone group mineral powder were mixed to obtain a mixture.

[0081] According to the specifications of the insulation cover to be produced, the required amount of mixture is placed into the corresponding mold and vacuum filtered to obtain the insulation cover blank; wherein, the vacuum pressure is above 5MPa.

[0082] The insulation cover plate blank is placed on a special tray and then transferred into a drying kiln at 90°C. The temperature is slowly increased to 100°C in 1 hour, and then the temperature is increased to 120°C in 2 hours. The temperature is increased to 130°C in 2 hours, and then the temperature is increased to 150°C in 2 hours. The temperature is then maintained at 150°C for 8 hours, and then the temperature is lowered. A sample is taken and the moisture content is tested to be ≤1wt%, thus obtaining the insulation cover plate.

[0083] The performance of the prepared thermal insulation cover was tested, and the results are shown in Table 1.

[0084] Table 1

[0085]

[0086] This invention is not limited to the above-described embodiments. Any modifications, improvements, or substitutions that can be conceived by those skilled in the art without departing from the essential content of this invention fall within the scope of this invention.

Claims

1. A heat-insulating cover plate, characterized in that, It includes the following components: 250-300 parts of the composite material used to improve the thermal insulation performance of the thermal insulation cover plate. 100-150 parts silica sand Combine with 25-35 parts of clay-diatomaceous earth. 10-15 parts of modified phenolic resin, 20-30 parts organic fiber 5-10 parts of blue-pinai mineral powder; The mass ratio of clay to diatomaceous earth is 1:

1. Wherein, the complex is calculated on a dry weight basis; The complex includes the following components: 50-70 parts SiO2 micro powder, 5-15 parts α-Al2O3 micro powder, 25-40 parts mullite refractory fiber, 10-15 parts carboxymethyl cellulose composite binder, and 180-550 parts water.

2. The heat-insulating cover plate according to claim 1, characterized in that, The silica sand contains ≤99wt% SiO2 and has a particle size of ≥90% passing through a 200-mesh sieve; the organic fiber is a fiber formed from at least one of wheat straw, corn stalks, reed stalks, and rice straw.

3. The heat-insulating cover plate according to claim 1, characterized in that, The particle size of SiO2 micro powder is 0.1–0.5 μm, and the specific surface area is 15–30 m². 2 / g; The SiO2 content in the SiO2 micro powder is 87-98wt%.

4. The heat-insulating cover plate according to claim 1, characterized in that, The particle size of α-Al2O3 micro powder is 0.3-0.6 μm; the content of Al2O3 in α-Al2O3 micro powder is ≤99wt%.

5. The heat-insulating cover plate according to claim 1, characterized in that, Mullite refractory fibers have a refractory temperature ≥1500℃ and a diameter of 3~5μm.

6. The heat-insulating cover plate according to claim 1, characterized in that, The complex consists of only the following components: 50-70 parts SiO2 micro powder, 5-15 parts α-Al2O3 micro powder, 25-40 parts mullite refractory fiber, 10-15 parts carboxymethyl cellulose composite binder, and 180-550 parts water.

7. The heat-insulating cover plate according to claim 1, characterized in that, The preparation method of the complex includes the following steps: A premix of SiO2 micro powder, α-Al2O3 micro powder, mullite refractory fiber and carboxymethyl cellulose binder was obtained; the premix was then mixed with water and stirred to obtain a composite material.

8. The heat-insulating cover plate according to claim 7, characterized in that, The premix is ​​mixed with water and stirred in a pulper for 10-20 minutes to obtain the complex.

9. The method for producing the thermal insulation cover plate according to claim 1, characterized in that, Includes the following steps: 1) According to the corresponding weight parts, the composite, silica sand, bonded clay-diatomaceous earth, modified phenolic resin, organic fiber, and bluestone group mineral powder are mixed to obtain a mixture; 2) Place the mixture into a mold and perform vacuum filtration to obtain the insulation cover plate blank; 3) Dry the insulation cover plate blank to obtain the insulation cover plate.

Images