Black body glaze for steel rolling heating furnace and preparation method of black body glaze

Abstract

The invention relates to blackbody glaze for a steel rolling heating furnace and a preparation method thereof, and belongs to the technical field of novel coatings. The blackbody glaze for the steel rolling heating furnace comprises the following components in parts by mass: 15-25 parts of a blackbody material, 70-80 parts of glaze, 40-50 parts of a porous geopolymer, 70-80 parts of a binder and 10-15 parts of water. In the preparation process of the porous geopolymer, the curing temperature is low, and ammonium bicarbonate is slowly decomposed to generate large bubbles in the curing process, so that large pores which are communicated with one another are formed in the geopolymer. In the high-temperature sintering process, the polymethyl methacrylate is decomposed to generate volatile substances to form small pore diameters, and the silica sol is decomposed and volatilized on the inner walls of the large pores at high temperature to form small pores, so that the porous geopolymer disclosed by the invention forms a hierarchical porous structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of new coating, and particularly relates to a black body glaze for a steel rolling heating furnace and a preparation method thereof. Background Art

[0002] The normal operating temperature of a steel rolling heating furnace is generally 1250 - 1350 °C. For the refractory effect, the working lining of the steel rolling heating furnace is generally built with light refractory materials. Currently, the commonly used materials for the lining of the steel rolling heating furnace are generally high-aluminum castables, aluminosilicate castables, and spinel castables. When these castables are dried, pores will be formed on the castables due to the evaporation of moisture or the decomposition of impurities in the castables to generate gas. Inevitably, acidic gases will be generated during the combustion of furnace gas and natural gas in the heating furnace. These acidic gases will corrode the castables and cause the castables to fall off. In the prior art, high-temperature glazes are often applied on the surface of refractory materials to protect the refractory materials. However, the glaze will present a molten state at high temperatures, which will affect the bonding between the glaze and the refractory material matrix, and thus lead to the peeling of the glaze layer. Summary of the Invention

[0003] The first object of the present invention is to provide a black body glaze for a steel rolling heating furnace to solve the technical problem that the glaze presents a molten state at high temperatures and affects the bonding between the glaze and the refractory material matrix.

[0004] The second object of the present invention is to provide a preparation method of the black body glaze for a steel rolling heating furnace.

[0005] In order to achieve the above objects, the technical solutions adopted by the present invention are as follows: A black body glaze for a steel rolling heating furnace, calculated by mass, includes 15 - 25 parts of black body material, 70 - 80 parts of glaze, 40 - 50 parts of porous geopolymer, 70 - 80 parts of binder, and 10 - 15 parts of water.

[0006] Further, the preparation method of the porous geopolymer is as follows: Mix 50 - 70 parts by mass of alkali activator, 5 - 10 parts by mass of foaming agent, 3 - 5 parts by mass of foam stabilizer, and 35 - 40 parts by mass of metakaolin to form a geopolymer slurry. After stirring evenly, seal and cure it, and then obtain it after curing.

[0007] Further, the foaming agent is a mixture of ammonium bicarbonate and polymethyl methacrylate, and the mass ratio of ammonium bicarbonate to polymethyl methacrylate is 1:1 - 5; the foam stabilizer is silica sol.

[0008] Further, the preparation method of the alkali activator is to mix 5 - 10 parts by mass of strong base and 50 - 60 parts by mass of sodium silicate solution, and then obtain it; the strong base is sodium hydroxide.

[0009] Further, the curing temperature is 25 - 60 °C and the curing time is 24 - 48 h; the curing temperature is 20 - 30 °C and the curing time is 3 - 14 d.

[0010] Further, calculated by mass, the blackbody material includes 3 - 5 parts of cobalt oxide, 7 - 8 parts of nickel oxide, and 87 - 90 parts of iron oxide.

[0011] Further, calculated by mass, the glaze includes 15 - 20 parts of potassium feldspar powder, 5 - 15 parts of sodium feldspar powder, 35 - 60 parts of kaolin, and 15 - 30 parts of alumina.

[0012] Further, the binder is an aluminum dihydrogen phosphate solution with a mass fraction of 45 - 55%.

[0013] The preparation method of the blackbody glaze for a rolling mill heating furnace as described above includes the following steps: S1: Mix the formula amount of the blackbody material, glaze, binder, porous geopolymer, and water, and then ball mill for 6 - 8 h to obtain a slurry. S2: Remove the dust and impurities on the surface of the refractory material substrate of the inner lining of the rolling mill heating furnace, and then apply the slurry on the surface of the refractory material substrate. S3: Dry at room temperature, then heat up to 600 - 1000 °C at a heating rate of 2 - 3 °C / min, hold for 2 - 3 h, then heat up to 1200 - 1400 °C at a heating rate of 5 - 10 °C / min, hold for 3 - 5 h, and then cool to obtain the product.

[0014] Further, the thickness of the applied slurry is 2 - 3 mm.

[0015] The beneficial effects of the present invention: During the preparation process of the porous geopolymer, the curing temperature is relatively low. During the curing process, ammonium bicarbonate slowly decomposes to generate large bubbles, forming larger and interconnected pores inside the geopolymer. During the high-temperature sintering process, polymethyl methacrylate decomposes to generate volatile substances to form smaller pore diameters, and silica sol also decomposes and volatilizes at high temperatures to form small pores on the inner wall of the large pores, enabling the porous geopolymer of the present invention to form a multi-level pore structure. Under the action of the porous geopolymer, when the blackbody glaze for a rolling mill heating furnace is in a molten state, the liquid blackbody glaze for a rolling mill heating furnace will wet the surface of the porous geopolymer to form a solid-liquid phase change interface. The internal pore channels of the porous geopolymer will adsorb the blackbody glaze for a rolling mill heating furnace, avoiding uneven flow distribution of the blackbody glaze for a rolling mill heating furnace in the molten state. The internal pore channels of the porous geopolymer of the present invention are of different sizes. The large pore channels provide storage space and flow channels for the blackbody glaze for a rolling mill heating furnace in the molten state, and the small pore diameters enhance the capillary adsorption force and improve the adsorption capacity of the porous geopolymer.

[0016] The blackbody material of the present invention has stable chemical properties at high temperatures, can withstand extreme temperatures, can maintain the mechanical strength of the blackbody glaze for rolling mill heating furnaces, reduce the risk of cracking and spalling. At the same time, the oxides in the blackbody material have a high infrared emissivity, can effectively absorb and emit thermal radiation, and reduce heat loss. Detailed implementation mode

[0017] The present invention will be further described below in conjunction with the embodiments of the present invention.

[0018] The concentration of the sodium silicate solution is 20 wt%.

[0019] Example 1

[0020] The preparation method of the blackbody glaze for rolling mill heating furnaces in Example 1 includes the following steps:

[0021] S1: Mix 3 kg of cobalt oxide, 8 kg of nickel oxide, and 89 kg of iron oxide to prepare the blackbody material; mix 20 kg of potassium feldspar powder, 10 kg of sodium feldspar powder, 50 kg of kaolin, and 20 kg of alumina to prepare the glaze; S2: Take 15 kg of the blackbody material, 70 kg of the glaze, 45 kg of the porous geopolymer, 70 kg of the aluminum dihydrogen phosphate solution with a mass fraction of 45%, and 10 kg of water, mix them and ball mill for 6 h to obtain the slurry; S2: Remove the dust and impurities on the surface of the refractory material substrate of the inner lining of the rolling mill heating furnace, and then apply the slurry in S2 on the surface of the refractory material substrate, with a coating thickness of 2 mm; S3: First dry at room temperature, then heat up to 600 °C at a heating rate of 2 °C / min, keep warm for 3 h, then heat up to 1400 °C at a heating rate of 8 °C / min, keep warm for 3 h, and obtain the product after cooling.

[0022] The preparation method of the porous geopolymer is as follows: Mix 5 kg of sodium hydroxide and 50 kg of the sodium silicate solution, cool down to room temperature to obtain the alkali activator, add 2 kg of ammonium bicarbonate, 5 kg of polymethyl methacrylate, and 3 kg of silica sol to the alkali activator, stir evenly, then add 35 kg of metakaolin and stir evenly to obtain the geopolymer slurry. Then cure at 50 °C for 30 h, cure at 20 °C for 5 d, demold to obtain the porous geopolymer, grind the obtained porous geopolymer, and pass through a 200-mesh sieve to obtain it.

[0023] Example 2 The preparation method of the blackbody glaze for rolling mill heating furnaces in Example 2 includes the following steps:

[0024] S1: Mix 5 kg of cobalt oxide, 7.5 kg of nickel oxide, and 90 kg of iron oxide to prepare a black body material; mix 15 kg of potassium feldspar powder, 5 kg of albite powder, 35 kg of kaolin, and 30 kg of alumina to prepare a glaze; S2: Take 25 kg of the black body material, 80 kg of the glaze, 50 kg of porous geopolymer, 80 kg of aluminum dihydrogen phosphate solution with a mass fraction of 50%, and 15 kg of water, mix them and ball mill for 8 h to obtain a slurry; S2: Remove the dust and impurities on the surface of the refractory material substrate of the inner lining of the steel rolling heating furnace, and then apply the slurry in S2 on the surface of the refractory material substrate, with a coating thickness of 3 mm; S3: First dry at room temperature, then heat up to 800 °C at a heating rate of 3 °C / min, hold for 2 h, then heat up to 1200 °C at a heating rate of 10 °C / min, hold for 5 h, and obtain the product after cooling.

[0025] The preparation method of the porous geopolymer is as follows: Mix 10 kg of sodium hydroxide and 55 kg of sodium silicate solution, cool down to room temperature to obtain an alkali activator, add 3 kg of ammonium bicarbonate, 7 kg of polymethyl methacrylate, and 4 kg of silica sol to the alkali activator, stir evenly, then add 40 kg of metakaolin and stir evenly to obtain a geopolymer slurry, then cure at 40 °C for 48 h, cure at 30 °C for 3 d, demold to obtain the porous geopolymer, grind the obtained porous geopolymer, and pass through a 200-mesh sieve to obtain it.

[0026] Example 3 The preparation method of the black body glaze for the steel rolling heating furnace in Example 3 includes the following steps:

[0027] S1: Mix 4 kg of cobalt oxide, 8 kg of nickel oxide, and 87 kg of iron oxide to prepare a black body material; mix 20 kg of potassium feldspar powder, 15 kg of albite powder, 60 kg of kaolin, and 30 kg of alumina to prepare a glaze; S2: Mix 20 kg of the black body material, 75 kg of the glaze, 40 kg of porous geopolymer, 75 kg of aluminum dihydrogen phosphate solution with a mass fraction of 45%, and 10 kg of water, mix them and ball mill for 6 h to obtain a slurry; S2: Remove the dust and impurities on the surface of the refractory material substrate of the inner lining of the steel rolling heating furnace, and then apply the slurry in S2 on the surface of the refractory material substrate, with a coating thickness of 2 mm; S3: First dry at room temperature, then heat up to 1000 °C at a heating rate of 3 °C / min, hold for 3 h, then heat up to 1200 °C at a heating rate of 5 °C / min, hold for 3 h, and obtain the product after cooling.

[0028] The preparation method of the porous geopolymer is as follows: 8 kg of sodium hydroxide and 60 kg of sodium silicate solution are mixed and cooled to room temperature to obtain an alkali activator. 1 kg of ammonium bicarbonate, 5 kg of polymethyl methacrylate, and 5 kg of silica sol are added to the alkali activator and stirred evenly. Then, 30 kg of metakaolin is added and stirred evenly to obtain a geopolymer slurry. Subsequently, it is cured at 60 °C for 24 h and cured at 20 °C for 14 d. After demolding, the porous geopolymer is obtained, and the obtained porous geopolymer is ground and sieved through a 200-mesh sieve to obtain the product.

[0029] Comparative Example 1 The preparation method of the blackbody glaze for the steel rolling heating furnace in Comparative Example 1 is substantially the same as that in Example 1. The difference between the preparation method of the blackbody glaze for the steel rolling heating furnace in Comparative Example 1 and that in Example 1 is that no porous geopolymer is added in Comparative Example 1.

[0030] Comparative Example 2 The preparation method of the blackbody glaze for the steel rolling heating furnace in Comparative Example 2 is substantially the same as that in Example 1. The difference between the preparation method of the blackbody glaze for the steel rolling heating furnace in Comparative Example 2 and that in Example 1 is that the foaming agent in Comparative Example 2 is 7 kg of ammonium bicarbonate.

[0031] Comparative Example 3 The preparation method of the blackbody glaze for the steel rolling heating furnace in Comparative Example 3 is substantially the same as that in Example 1. The difference between the preparation method of the blackbody glaze for the steel rolling heating furnace in Comparative Example 3 and that in Example 1 is that the foaming agent in Comparative Example 3 is 7 kg of polymethyl methacrylate.

[0032] Comparative Example 4 The preparation method of the blackbody glaze for the steel rolling heating furnace in Comparative Example 4 is substantially the same as that in Example 1. The difference between the preparation method of the blackbody glaze for the steel rolling heating furnace in Comparative Example 4 and that in Example 1 is that the mass of the blackbody material added in the blackbody glaze for the steel rolling heating furnace in Comparative Example 4 is 10 kg, and the mass of the glaze added is 80 kg.

[0033] Performance test: 1. The blackbody glazes for the steel rolling heating furnace prepared in Examples 1-3 and Comparative Examples 1-4 are subjected to performance detection according to the inspection method of ASTM C 1371-04; 2. The blackbody glaze for the steel rolling heating furnace is calcined at 1500 °C for 30 days for performance detection; 3. The thermal shock resistance performance test is carried out according to Method 1 (water quenching method) in GB / T30873-2014 "Test Method for Thermal Shock Resistance of Refractories".

[0034] The performance test results are shown in Table 1.

[0035] Table 1 Performance test results of blackbody glaze for steel rolling heating furnace in Examples 1-3 and Comparative Examples 1-4

[0036] As can be seen from Table 1, when the porous geopolymer was not added in Comparative Example 1, the blackbody glaze for the steel rolling heating furnace showed a molten state during use, and over time, the blackbody glaze for the steel rolling heating furnace would slide off, resulting in uneven distribution of the blackbody glaze for the steel rolling heating furnace and easy shedding. When only polymethyl methacrylate or ammonium bicarbonate was added as a foaming agent in Comparative Examples 2 and 3, the pore sizes generated by foaming were relatively single, resulting in poor adsorption effect of the porous geopolymer, and part of the blackbody glaze for the steel rolling heating furnace would fall off. When the content of the blackbody material in Comparative Example 4 decreased, the infrared emissivity, energy saving rate, and improvement rate of thermal efficiency of the blackbody glaze for the steel rolling heating furnace all decreased significantly.

Claims

1. A black body glaze for a steel rolling heating furnace, characterized in that, By mass, it includes 15 - 25 parts of black body material, 70 - 80 parts of glaze, 40 - 50 parts of porous geopolymer, 70 - 80 parts of binder, and 10 - 15 parts of water.

2. The black body glaze for a steel rolling heating furnace according to claim 1, characterized in that, The preparation method of the porous geopolymer is as follows: Mix 50 - 70 parts by mass of alkali activator, 5 - 10 parts by mass of foaming agent, 3 - 5 parts by mass of foam stabilizer, and 35 - 40 parts by mass of metakaolin to form a geopolymer slurry. After stirring evenly, seal it for curing, and obtain it after curing.

3. The black glaze for a steel rolling heating furnace according to claim 2, characterized in that, The foaming agent is a mixture of ammonium bicarbonate and polymethyl methacrylate, and the mass ratio of ammonium bicarbonate to polymethyl methacrylate is 1:1 - 5; the foam stabilizer is silica sol.

4. The black body glaze for a steel rolling heating furnace according to claim 2, wherein, The preparation method of the alkali activator is to mix 5 - 10 parts by mass of strong alkali with 50 - 60 parts by mass of sodium silicate solution, and then obtain it; the strong alkali is sodium hydroxide.

5. The black glaze for steel rolling heating furnace according to claim 2, characterized in that, The temperature of the curing is 25 - 60 °C, and the time of the curing is 24 - 48 h; the temperature of the curing is 20 - 30 °C, and the time of the curing is 3 - 14 d.

6. The black glaze for a rolling mill reheating furnace according to claim 1, characterized in that, The black body material by mass includes 3 - 5 parts of cobalt oxide, 7 - 8 parts of nickel oxide, and 87 - 90 parts of iron oxide.

7. The black glaze for a rolling mill heating furnace according to claim 1, characterized in that, The glaze by mass includes 15 - 20 parts of potassium feldspar powder, 5 - 15 parts of sodium feldspar powder, 35 - 60 parts of kaolin, and 15 - 30 parts of alumina.

8. The black body glaze for a steel rolling heating furnace according to claim 1, characterized in that, The binder is an aluminum dihydrogen phosphate solution with a mass fraction of 45 - 55%.

9. The preparation method of the blackbody glaze for a steel rolling heating furnace according to claim 1, characterized in that, It includes the following steps: S1: Mix the black body material, glaze, binder, porous geopolymer, and water in the formula amount, and then ball mill for 6 - 8 h to obtain a slurry. S2: Remove the dust and impurities on the surface of the refractory material substrate of the inner lining of the steel rolling heating furnace, and then apply the slurry on the surface of the refractory material substrate. S3: Dry at room temperature, then heat up to 600 - 1000 °C at a heating rate of 2 - 3 °C / min, keep warm for 2 - 3 h, then heat up to 1200 - 1400 °C at a heating rate of 5 - 10 °C / min, keep warm for 3 - 5 h, and obtain it after cooling.

10. The preparation method of the blackbody glaze for the steel rolling heating furnace according to claim 9, characterized in that, The thickness of the applied slurry is 2 - 3 mm.

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