Black body glaze for steel rolling heating furnace and preparation method thereof

Abstract

The present invention relates to a black body glaze for a steel rolling heating furnace and a preparation method thereof, and belongs to the field of novel coating technology. The black body glaze for a steel rolling heating furnace comprises, by weight, 15-25 parts of a black body material, 70-80 parts of a glaze, 40-50 parts of a porous geopolymer, 70-80 parts of a binder, and 10-15 parts of water. During the preparation of the porous geopolymer, the curing temperature is relatively low, and during the curing process, ammonium bicarbonate slowly decomposes to produce large bubbles, thereby forming relatively large and interconnected pores inside the geopolymer. During the high-temperature sintering process, polymethyl methacrylate decomposes to produce volatile substances to form smaller pores, and silica sol also decomposes and volatilizes at high temperatures to form small pores on the inner wall of the large pores, so that the porous geopolymer of the present invention forms a multi-level porous structure.

Description

Technical Field

[0001] The invention belongs to the technical field of novel coatings, and in particular 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 ℃, and the lining of a steel rolling heating furnace is generally built with lightweight refractory materials to achieve a refractory effect. The materials used for the lining of a steel rolling heating furnace commonly used at present are generally high-aluminum castables, aluminum silicate castables and spinel castables. These castables will produce gas to form pores on the castables due to water evaporation or decomposition of impurities in the castables during drying, and acidic gases will inevitably be generated when the heating furnace gas and natural gas are burned. These acidic gases will corrode the castables and cause them to fall off. In the existing technology, high-temperature glaze is often applied to the surface of the refractory material to protect the refractory material. However, the glaze will be in a molten state at high temperatures, which will affect the bonding between the glaze and the refractory matrix, and thus cause the glaze layer to peel off. 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 is in a molten state at high temperature and affects the bonding of the glaze with the refractory material substrate.

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

[0005] In order to achieve the above objectives, the technical solution adopted by the present invention is:

[0006] A black body glaze for a steel rolling heating furnace comprises, by weight, 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.

[0007] Furthermore, the porous geopolymer is prepared by mixing 50-70 parts by mass of an alkali activator, 5-10 parts by mass of a foaming agent, 3-5 parts by mass of a foam stabilizer, and 35-40 parts by mass of metakaolin to form a geopolymer slurry, stirring the mixture evenly, sealing and solidifying the mixture, and then curing the mixture to obtain the geopolymer slurry.

[0008] Furthermore, the foaming agent is a mixture of ammonium bicarbonate and polymethyl methacrylate, and the mass ratio of the ammonium bicarbonate to the polymethyl methacrylate is 1:1-5; and the foam stabilizing agent is silica sol.

[0009] Furthermore, the preparation method of the alkaline activator is to mix 5-10 parts by mass of a strong base with 50-60 parts by mass of a sodium silicate solution; the strong base is sodium hydroxide.

[0010] Furthermore, the curing temperature is 25-60°C, and the curing time is 24-48 hours; the curing temperature is 20-30°C, and the curing time is 3-14 days.

[0011] Furthermore, the black body material comprises 3-5 parts of cobalt oxide, 7-8 parts of nickel oxide, and 87-90 parts of iron oxide in parts by mass.

[0012] Furthermore, the glaze comprises, by mass, 15-20 parts of potassium feldspar powder, 5-15 parts of sodium feldspar powder, 35-60 parts of kaolin, and 15-30 parts of aluminum oxide.

[0013] Furthermore, the binder is a 45-55% by mass aluminum dihydrogen phosphate solution.

[0014] The method for preparing the black body glaze for a steel rolling heating furnace as described above comprises the following steps:

[0015] S1: Mix the blackbody material, glaze, binder, porous geopolymer, and water in the formulated amount and ball mill for 6-8 hours to obtain a slurry;

[0016] S2: removing dust and impurities from the surface of the refractory substrate of the steel rolling heating furnace lining, and then applying the slurry to the surface of the refractory substrate;

[0017] S3: Dry at room temperature, then heat to 600-1000 °C at a heating rate of 2-3 °C / min, keep warm for 2-3 h, then heat to 1200-1400 °C at a heating rate of 5-10 °C / min, keep warm for 3-5 h, and cool to obtain.

[0018] Furthermore, the slurry is applied to a thickness of 2-3 mm.

[0019] Beneficial effects of the present invention:

[0020] During the preparation of the porous geopolymer, the curing temperature is relatively low. During the curing process, ammonium bicarbonate slowly decomposes to produce large bubbles, which causes large, interconnected pores to form within the geopolymer. During the high-temperature sintering process, polymethyl methacrylate decomposes to produce volatile substances, forming smaller pores. Silica sol also decomposes and volatilizes at high temperatures to form small pores on the inner walls of the large pores, allowing the porous geopolymer of the present invention to form a multi-level porous structure. Under the action of the porous geopolymer, when the black body glaze for steel rolling heating furnaces is in a molten state, the black body glaze for steel rolling heating furnaces in the liquid state will wet the surface of the porous geopolymer to form a solid-liquid phase transition interface. The internal pores of the porous geopolymer will adsorb the black body glaze for steel rolling heating furnaces, preventing uneven flow distribution of the black body glaze for steel rolling heating furnaces in the molten state. The internal pores of the porous geopolymer of the present invention vary in size. The large pores provide storage space and flow channels for the black body glaze for steel rolling heating furnaces in the molten state, while the small pores enhance capillary adsorption, thereby improving the adsorption capacity of the porous geopolymer.

[0021] 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 used in steel rolling heating furnaces, and reduce the risks of cracking and peeling. At the same time, the oxide in the blackbody material has a high infrared emissivity, can effectively absorb and emit thermal radiation, and reduce heat loss. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the embodiments of the present invention.

[0023] The concentration of the sodium silicate solution was 20 wt%.

[0024] Example 1

[0025] The method for preparing the black body glaze for a steel rolling heating furnace of Example 1 comprises the following steps:

[0026] S1: 3 kg of cobalt oxide, 8 kg of nickel oxide, and 89 kg of iron oxide are mixed to prepare the black body material; 20 kg of potassium feldspar powder, 10 kg of sodium feldspar powder, 50 kg of kaolin, and 20 kg of aluminum oxide are mixed to prepare the glaze;

[0027] S2: 15 kg of blackbody material, 70 kg of glaze, 45 kg of porous geopolymer, 70 kg of 45% aluminum dihydrogen phosphate solution, and 10 kg of water were mixed and ball-milled for 6 h to obtain a slurry;

[0028] S2: Remove dust and impurities from the surface of the refractory base material of the steel rolling heating furnace lining, and then apply the slurry in S2 to the surface of the refractory base material with a thickness of 2 mm;

[0029] S3: First dry at room temperature, then heat to 600 °C at a heating rate of 2 °C / min, keep warm for 3 h, then heat to 1400 °C at a heating rate of 8 °C / min, keep warm for 3 h, and cool to obtain.

[0030] The preparation method of the porous geopolymer is as follows: 5 kg of sodium hydroxide and 50 kg of sodium silicate solution are mixed and then cooled to room temperature to obtain an alkaline activator, 2 kg of ammonium bicarbonate, 5 kg of polymethyl methacrylate, and 3 kg of silica sol are added to the alkaline activator and stirred evenly, then 35 kg of metakaolin is added and stirred evenly to obtain a geopolymer slurry, which is then cured at 50°C for 30 hours and cured at 20°C for 5 days. After demolding, the porous geopolymer is obtained, and the obtained porous geopolymer is ground and passed through a 200-mesh sieve.

[0031] Example 2

[0032] The method for preparing the black body glaze for a steel rolling heating furnace of Example 2 comprises the following steps:

[0033] S1: 5 kg of cobalt oxide, 7.5 kg of nickel oxide, and 90 kg of iron oxide were mixed to prepare a black body material; 15 kg of potassium feldspar powder, 5 kg of sodium feldspar powder, 35 kg of kaolin, and 30 kg of aluminum oxide were mixed to prepare a glaze;

[0034] S2: 25 kg of blackbody material, 80 kg of glaze, 50 kg of porous geopolymer, 80 kg of 50% aluminum dihydrogen phosphate solution, and 15 kg of water were mixed and ball-milled for 8 h to obtain a slurry;

[0035] S2: Remove dust and impurities from the surface of the refractory base material of the steel rolling heating furnace lining, and then apply the slurry in S2 to the surface of the refractory base material with a thickness of 3 mm;

[0036] S3: First dry at room temperature, then heat to 800 °C at a heating rate of 3 °C / min, keep warm for 2 h, then heat to 1200 °C at a heating rate of 10 °C / min, keep warm for 5 h, and then cool to obtain.

[0037] The preparation method of the porous geopolymer is as follows: 10 kg of sodium hydroxide and 55 kg of sodium silicate solution are mixed and then cooled to room temperature to obtain an alkaline activator, 3 kg of ammonium bicarbonate, 7 kg of polymethyl methacrylate, and 4 kg of silica sol are added to the alkaline activator and stirred evenly, then 40 kg of metakaolin is added and stirred evenly to obtain a geopolymer slurry, which is then cured at 40°C for 48 hours and maintained at 30°C for 3 days. After demolding, the porous geopolymer is obtained, and the obtained porous geopolymer is ground and passed through a 200-mesh sieve.

[0038] Example 3

[0039] The method for preparing the black body glaze for a steel rolling heating furnace of Example 3 comprises the following steps:

[0040] S1: 4 kg of cobalt oxide, 8 kg of nickel oxide, and 87 kg of iron oxide were mixed to prepare a black body material; 20 kg of potassium feldspar powder, 15 kg of sodium feldspar powder, 60 kg of kaolin, and 30 kg of aluminum oxide were mixed to prepare a glaze;

[0041] S2: 20 kg of blackbody material, 75 kg of glaze, 40 kg of porous geopolymer, 75 kg of 45% aluminum dihydrogen phosphate solution, and 10 kg of water were mixed and ball-milled for 6 h to obtain a slurry;

[0042] S2: Remove dust and impurities from the surface of the refractory base material of the steel rolling heating furnace lining, and then apply the slurry in S2 to the surface of the refractory base material with a thickness of 2 mm;

[0043] S3: First dry at room temperature, then heat to 1000 °C at a heating rate of 3 °C / min, keep warm for 3 h, then heat to 1200 °C at a heating rate of 5 °C / min, keep warm for 3 h, and then cool to obtain.

[0044] 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 then cooled to room temperature to obtain an alkaline activator, 1 kg of ammonium bicarbonate, 5 kg of polymethyl methacrylate, and 5 kg of silica sol are added to the alkaline activator and stirred evenly, then 30 kg of metakaolin is added and stirred evenly to obtain a geopolymer slurry, which is then cured at 60°C for 24 hours and cured at 20°C for 14 days. After demolding, the porous geopolymer is obtained, and the obtained porous geopolymer is ground and passed through a 200-mesh sieve.

[0045] Comparative Example 1

[0046] The preparation method of the black body glaze for 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 black body glaze for steel rolling heating furnace in Comparative Example 1 and Example 1 is that porous geopolymer is not added in Comparative Example 1.

[0047] Comparative Example 2

[0048] The preparation method of the black body glaze for 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 black body glaze for steel rolling heating furnace in Comparative Example 2 and Example 1 is that the foaming agent in Comparative Example 2 is 7 kg of ammonium bicarbonate.

[0049] Comparative Example 3

[0050] The preparation method of the black body glaze for the steel rolling heating furnace in Comparative Example 3 is roughly the same as that in Example 1. The difference between the preparation method of the black body glaze for the steel rolling heating furnace in Comparative Example 3 and Example 1 is that the foaming agent in Comparative Example 3 is 7 kg of polymethyl methacrylate.

[0051] Comparative Example 4

[0052] The preparation method of the black body glaze for steel rolling heating furnace in Comparative Example 4 is roughly the same as that in Example 1. The difference between the preparation method of the black body glaze for steel rolling heating furnace in Comparative Example 4 and Example 1 is that the mass of the black body material added to the black body glaze for steel rolling heating furnace in Comparative Example 4 is 10 kg, and the mass of the glaze added is 80 kg.

[0053] Performance testing:

[0054] 1. The black body glazes for steel rolling heating furnaces prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance testing according to the ASTM C 1371-04 inspection method;

[0055] 2. The black body glaze for steel rolling heating furnace was calcined at 1500℃ for 30 days to perform performance test;

[0056] 3. Conduct thermal shock resistance test according to Method 1 (water quenching method) in GB / T30873-2014 "Test method for thermal shock resistance of refractory materials".

[0057] The performance test results are shown in Table 1.

[0058] Table 1 Performance test results of black body glaze for steel rolling heating furnace in Examples 1-3 and Comparative Examples 1-4

[0059]

[0060] As can be seen from Table 1, in Comparative Example 1, when no porous geopolymer was added, the black body glaze for the steel rolling heating furnace remained molten during use. Over time, the black body glaze would slip, resulting in uneven distribution and easy detachment. In Comparative Examples 2 and 3, when only polymethyl methacrylate or ammonium bicarbonate was added as a foaming agent, the resulting pores were relatively uniform in size, resulting in poor adsorption of the porous geopolymer and partial detachment of the black body glaze. In Comparative Example 4, when the black body material content was reduced, the infrared emissivity, energy saving rate, and thermal efficiency improvement rate of the black body 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: The porous geopolymer comprises, by weight, 15-25 parts of blackbody material, 70-80 parts of glaze, 40-50 parts of porous geopolymer, 70-80 parts of binder, and 10-15 parts of water. The porous geopolymer is prepared by mixing 50-70 parts by weight of an alkali activator, 5-10 parts by weight of a foaming agent, 3-5 parts by weight of a foam stabilizer, and 35-40 parts by weight of metakaolin to form a geopolymer slurry, stirring the mixture uniformly, sealing, curing, and curing the mixture to obtain the geopolymer slurry. The foaming agent is a mixture of ammonium bicarbonate and polymethyl methacrylate, and the mass ratio of the ammonium bicarbonate to the polymethyl methacrylate is 1:1-5. The foam stabilizer is silica sol.

2. The black body glaze for steel rolling heating furnace according to claim 1, characterized in that: The preparation method of the alkali activator is to mix 5-10 parts by mass of a strong base with 50-60 parts by mass of a sodium silicate solution to obtain the activator; the strong base is sodium hydroxide.

3. The black body glaze for steel rolling heating furnace according to claim 1, characterized in that: The curing temperature is 25-60° C., and the curing time is 24-48 hours; the curing temperature is 20-30° C., and the curing time is 3-14 days.

4. The black body glaze for steel rolling heating furnace according to claim 1, characterized in that: The black body material comprises 3-5 parts of cobalt oxide, 7-8 parts of nickel oxide, and 87-90 parts of iron oxide in parts by mass.

5. The black body glaze for steel rolling heating furnace according to claim 1, characterized in that: The glaze comprises, by weight, 15-20 parts of potassium feldspar powder, 5-15 parts of sodium feldspar powder, 35-60 parts of kaolin, and 15-30 parts of aluminum oxide.

6. The black body glaze for 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%.

7. The method for preparing black body glaze for steel rolling heating furnace according to claim 1, characterized in that: The following steps are involved: S1: Mix the blackbody material, glaze, binder, porous geopolymer, and water in the formulated amount and ball mill for 6-8 hours to obtain a slurry; S2: removing dust and impurities from the surface of the refractory substrate of the steel rolling heating furnace lining, and then applying the slurry to the surface of the refractory substrate; S3: Dry at room temperature, then heat to 600-1000°C at a heating rate of 2-3°C / min, keep warm for 2-3h, then heat to 1200-1400°C at a heating rate of 5-10°C / min, keep warm for 3-5h, and cool to obtain.

8. The method for preparing black body glaze for steel rolling heating furnace according to claim 7, characterized in that: The slurry is applied to a thickness of 2-3 mm.

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