Special casting powder for Mn13 high-wear-resistance steel

Abstract

The invention relates to the technical field of casting powder, in particular to special casting powder for Mn13 high-wear-resistance steel, which comprises the following raw materials: premelting refining slag, composite coating carbon microspheres, manganese oxide particles, sodium carbonate, borax and bentonite. According to the special casting powder for the Mn13 high-wear-resistance steel, a silicate ceramic membrane on the outer layer in the composite coating carbon microspheres isolates oxygen at low temperature, and oxidation of carbon on the inner layer is delayed; along with the temperature rise, the ceramic membrane is molten, and the carbon layer is gradually released and continuously plays a flame-retardant role, so that the melting speed of the casting powder is accurately regulated and controlled, a stable structure is maintained in the whole continuous casting process, and effective heat preservation and air isolation are realized; meanwhile, the organic-inorganic composite film on the surface of the manganese oxide particles subjected to surface modification effectively prevents the particles from being sintered and aggregated at a high temperature, and the compatibility of the particles and a casting powder matrix is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of protective slag technology, and more specifically, to a protective slag specifically for Mn13 high wear-resistant steel. Background Technology

[0002] Due to its extremely high work hardening ability and excellent wear resistance, Mn13 high-manganese steel is widely used in the manufacture of wear-resistant parts that withstand strong impacts and high pressures, such as tank track plates and jaw plates of mining crushers. In the continuous casting process, protective slag must be used to prevent oxidation of molten steel, maintain heat, absorb inclusions, and control lubrication and heat transfer. However, the extremely high manganese content in Mn13 steel poses a great challenge to traditional protective slag. The manganese vapor released from the molten steel will undergo a reduction reaction with components such as iron oxide in the protective slag, generating a large amount of manganese oxide which dissolves into the slag, significantly changing the physicochemical properties of the protective slag, such as increasing the melting point, increasing the viscosity sharply, and increasing the crystallinity. This leads to a series of quality problems such as slag ring crusting, poor lubrication, and surface cracks in the billet, seriously affecting the smooth operation of continuous casting and the quality of the billet.

[0003] Traditional carbonaceous materials oxidize and burn too quickly, failing to provide a continuous and stable flame-retardant shielding effect throughout the melting process, resulting in an unstable protective slag melting structure. Ordinary manganese ore powder or manganese oxide powder is prone to sintering and agglomeration at high temperatures, and its compatibility with the protective slag matrix is ​​poor, failing to effectively buffer the performance abrupt changes caused by absorbing MnO floating in molten steel. In view of this, we propose a special protective slag for Mn13 high wear-resistant steel. Summary of the Invention

[0004] The purpose of this invention is to provide a special protective slag for Mn13 high wear-resistant steel, in order to solve the problems mentioned in the background art, such as the excessively rapid oxidation and combustion of traditional carbonaceous materials, which cannot provide a continuous and stable flame-retardant shielding effect throughout the melting process, resulting in an unstable melting structure of the protective slag; and the fact that ordinary manganese ore powder or manganese oxide powder is prone to sintering and agglomeration at high temperatures, and has poor compatibility with the protective slag matrix, which cannot effectively buffer the performance change caused by absorbing MnO floating in molten steel.

[0005] This invention provides a special protective slag for Mn13 high wear-resistant steel, comprising the following raw materials: pre-melted refining slag, composite coated carbon microspheres, manganese oxide particles, sodium carbonate, borax and bentonite; The composite coated carbon microspheres are prepared by first impregnating and coating the carbon microspheres with a phenolic resin solution and then curing them, followed by low-temperature carbonization to form an amorphous carbon barrier layer, and finally depositing a silicate ceramic film on its outer surface using a sol-gel method. Manganese oxide particles are prepared by forming an organic-inorganic composite film on the surface of propyl 3-(trimethoxysilyl)methacrylate.

[0006] Preferably, the pre-melted refining slag comprises 25-40 parts by weight, composite coated carbon microspheres comprises 3-8 parts by weight, manganese oxide particles comprises 5-15 parts by weight, sodium carbonate comprises 5-10 parts by weight, borax comprises 2-5 parts by weight, and bentonite comprises 3-5 parts by weight.

[0007] Preferably, the preparation process of the manganese oxide particles is as follows: Add 1.5-3.0% of 3-(trimethoxysilyl)methacrylate by mass of dried manganese oxide to ethanol to obtain a 1-2% 3-(trimethoxysilyl)methacrylate solution. Add 3-(trimethoxysilyl)methacrylate propyl ester solution dropwise to 3-5 times its total volume of ethanol / water medium, while stirring at 300-400 rpm at room temperature for 20-30 min to obtain a pre-hydrolyzed 3-(trimethoxysilyl)methacrylate propyl ester solution. Dry manganese oxide was added to a pre-hydrolyzed propyl 3-(trimethoxysilyl)methacrylate solution at a mass ratio of 1:1-2. The mixture was stirred at 500-1000 rpm at 25-40℃ for 2-3 hours. After the reaction was completed, the mixture was allowed to stand at 40-60℃ for 30-60 minutes to obtain a reaction slurry. The reaction slurry was filtered, washed twice with ethanol, and then rinsed once with deionized water. The filter cake was placed in a vacuum drying oven and dried at 80-100℃ for 6-12 hours until constant weight was obtained to obtain dried powder. The dried powder was placed in a nitrogen atmosphere at a flow rate of 0.5-2 L / min and heated to 250-300℃ at a rate of 5-10℃ / min. The temperature was maintained for 1 hour, then cooled to room temperature and removed. The powder was then sieved through an 80-150 mesh sieve to obtain manganese oxide particles.

[0008] Preferably, the ethanol / water medium is obtained by mixing ethanol and deionized water at a volume ratio of 4:1 at room temperature and adjusting the pH to 4.0-4.5 with 0.1 mol / L acetic acid.

[0009] Preferably, the preparation process of the composite coated carbon microspheres is as follows: The carbon microspheres were immersed in a 10-20% phenolic resin solution at a mass ratio of 1:5-10 for 5-20 minutes, then removed and centrifuged. The resin layer was then dried at 80-120℃ for 30-60 minutes to solidify the resin layer. The dip-coating / drying cycle was repeated 1-3 times to obtain the polymer-coated carbon microspheres. The polymer-coated carbon microspheres were placed in a nitrogen atmosphere furnace and heated to 400-600℃ at a rate of 5-10℃ / min, held at that temperature for 0.5-2h, and then cooled to room temperature in the furnace and removed. Carbon microspheres were added to silicate sol at a mass ratio of 1:10-20 and stirred at 50-100 rpm for 10-30 min. The mixture was filtered and dried at 80-120℃ for 2-6 h. It was then cured at 200-300℃ for 0.5-1 h under a nitrogen atmosphere by heating at 2-5℃ / min to obtain composite coated carbon microspheres with a total thickness of 0.05-1 μm.

[0010] By controlling the concentration of the phenolic resin solution and the number of impregnation-curing cycles, an amorphous carbon barrier layer that is not completely graphitized but sufficiently dense can be formed at a lower temperature (400-600℃).

[0011] Preferably, the silicate sol is obtained by mixing tetraethoxysilane with an equal volume of ethanol, adding deionized water in a molar ratio of 1:8-12 to tetraethoxysilane and hydrochloric acid accounting for 1-2% of the mass of tetraethoxysilane, and adjusting the pH to 8-9 by adding 0.5 mol / L ammonia water dropwise, and then stirring and hydrolyzing at 40-60°C for 2-4 hours.

[0012] As a preferred embodiment, the preparation process of the special protective slag for Mn13 high wear-resistant steel is as follows: S1.1 Weigh the following raw materials in parts by weight: 25-40 parts by weight of pre-melted refining slag, 3-8 parts by weight of composite coated carbon microspheres, 5-15 parts by weight of manganese oxide particles, 5-10 parts by weight of sodium carbonate, 2-5 parts by weight of borax and 3-5 parts by weight of bentonite. S1.2. Pour the pre-melted refining slag, sodium carbonate, borax, manganese oxide particles and bentonite into a double cone mixer, turn on the mixer and mix at a speed of 15-20 rpm for 30-45 minutes to obtain a mixed dry powder matrix. S1.3 Transfer the mixed dry powder matrix to a shear mixer. Add composite coated carbon microspheres while stirring at 15-20 rpm, and then mix for 15-20 minutes. At the same time, add deionized water to the mixed powder through a spray device and mix until the material is semi-wet. Then, granulate the mixed wet material through a granulator through a 10-20 mesh sieve to obtain wet granules. S1.4 Spread the wet granules evenly on the drying tray, then place them in a hot air circulating drying oven and dry them at 110-120℃ for 2-3 hours to reduce the moisture content of the granules to below 0.5%; transfer the dried granules into an atmosphere heat treatment furnace, and heat them to 280-350℃ under nitrogen protection and keep them at that temperature for 1-2 hours. S1.5 After the heat preservation is completed, the furnace is cooled to below 60°C and then removed under nitrogen atmosphere protection; a 40-100 mesh double-layer vibrating screen is used for sieving to obtain special protective slag for Mn13 high wear-resistant steel.

[0013] Preferably, in step S1.3, the amount of deionized water added is 5-8% of the total mass of the mixed powder.

[0014] Preferably, in step S1.4, the nitrogen flow rate is 1-2 L / min.

[0015] Preferably, in step S1.4, the heating rate is 3-5℃ / min.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: In this invention, a protective slag for Mn13 high wear-resistant steel is disclosed. The silicate ceramic film on the outer layer of the composite coated carbon microspheres isolates oxygen at low temperatures, delaying the oxidation of the inner carbonaceous layer. As the temperature rises, the ceramic film melts, and the carbon layer is gradually released and continues to exert a flame-retardant effect, thereby precisely controlling the melting rate of the protective slag and ensuring that it maintains a stable structure throughout the continuous casting process, effectively keeping it warm and isolating it from air. At the same time, the surface-modified manganese oxide particles have an organic-inorganic composite film on their surface that effectively prevents the particles from sintering and agglomerating at high temperatures and greatly improves their compatibility with the protective slag matrix. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] This invention provides a special protective slag for Mn13 high wear-resistant steel, comprising the following raw materials: pre-melted refining slag, composite coated carbon microspheres, manganese oxide particles, sodium carbonate, borax and bentonite; The composite coated carbon microspheres are prepared by first impregnating and coating the carbon microspheres with a phenolic resin solution and then curing them, followed by low-temperature carbonization to form an amorphous carbon barrier layer, and finally depositing a silicate ceramic film on its outer surface using a sol-gel method. Manganese oxide particles are prepared by forming an organic-inorganic composite film on the surface of propyl 3-(trimethoxysilyl)methacrylate.

[0019] The pre-melted refining slag (main chemical components are 35-45% CaO, 30-40% SiO2, 5-15% Al2O3, and 3-8% MgO) was purchased from Henan Shengshida Metallurgical Refractory Materials Co., Ltd.

[0020] Carbon microspheres (particle size range 10-30μm, carbon content >95%) were purchased from Hefei Zhongtan New Materials Technology Co., Ltd.

[0021] Phenolic resin CAS No.: 9003-35-4, purchased from Zibo Huasen Adhesives Co., Ltd.

[0022] Tetraethoxysilane, CAS No.: 78-10-4, was purchased from Shandong Ruiqi Chemical Co., Ltd.

[0023] Manganese oxide CAS No.: 1344-43-0, 3-(trimethoxysilyl)propyl methacrylate CAS No.: 2530-85-0, Sodium carbonate CAS No.: 497-19-8, Borax CAS No.: 1303-96-4, Bentonite CAS No.: 1302-78-9, purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0024] Drying manganese oxide involves spreading it evenly on a drying tray and placing it in a drying oven at 120°C for 2 hours.

[0025] The ethanol / water medium is obtained by mixing ethanol and deionized water at a volume ratio of 4:1 at room temperature and adjusting the pH to 4.5 with 0.1 mol / L acetic acid.

[0026] Example 1: A process for preparing a special protective slag for Mn13 high wear-resistant steel, comprising the following steps: S1.1 Weigh the following raw materials in parts by weight: 25 parts by weight of pre-melted refining slag, 3 parts by weight of composite coated carbon microspheres, 5 parts by weight of manganese oxide particles, 5 parts by weight of sodium carbonate, 2 parts by weight of borax and 3 parts by weight of bentonite. S1.2. Pour the pre-melted refining slag, sodium carbonate, borax, manganese oxide particles and bentonite into a double cone mixer, turn on the mixer and mix at 15 rpm for 30 minutes to obtain a mixed dry powder matrix. S1.3 Transfer the mixed dry powder matrix to a shear mixer and add composite coated carbon microspheres while stirring at 15 rpm. Mix and grind for another 15 minutes. At the same time, add 5% of the total mass of the mixed powder to the mixed powder through a spray device and mix until the material is semi-wet. Then, granulate the mixed wet material through a granulator through a 10-mesh sieve to obtain wet granules. S1.4 Spread the wet granules evenly on the drying tray, then place them in a hot air circulating drying oven and dry them at 110℃ for 2 hours to reduce the moisture content of the granules to below 0.5%; transfer the dried granules into an atmosphere heat treatment furnace, and heat them to 280℃ at a nitrogen flow rate of 1L / min with a nitrogen protection rate of 3℃ / min and hold for 1 hour. S1.5 After the heat preservation is completed, the furnace is cooled to below 60°C and then removed under nitrogen atmosphere protection; a 40-mesh double-layer vibrating screen is used for sieving to obtain special protective slag for Mn13 high wear-resistant steel.

[0027] The preparation process of manganese oxide particles is as follows: 1.5% of the mass of dried manganese oxide propyl 3-(trimethoxysilyl)methacrylate was added to ethanol to obtain a 1% mass concentration propyl 3-(trimethoxysilyl)methacrylate solution. A 3-(trimethoxysilyl)methacrylate propyl ester solution was added dropwise to an ethanol / water medium with a total volume of 3 times its volume, while stirring at 300 rpm at room temperature for 20 min to obtain a pre-hydrolyzed 3-(trimethoxysilyl)methacrylate propyl ester solution. Dry manganese oxide was added to a pre-hydrolyzed propyl 3-(trimethoxysilyl)methacrylate solution at a mass ratio of 1:1. The mixture was stirred at 500 rpm at 25°C for 2 hours. After the reaction was completed, the mixture was allowed to stand at 40°C for 30 minutes to obtain a reaction slurry. The reaction slurry was filtered, washed twice with ethanol, and then rinsed once with deionized water. The filter cake was placed in a vacuum drying oven and dried at 80°C for 6 hours until constant weight was obtained to obtain dried powder. The dried powder was placed in a nitrogen atmosphere at a flow rate of 0.5 L / min and heated to 280 °C at a rate of 5 °C / min. The temperature was maintained for 1 hour, then cooled to room temperature and removed. The powder was then sieved through an 80-mesh sieve to obtain manganese oxide particles.

[0028] The preparation process of composite coated carbon microspheres is as follows: The carbon microspheres were immersed in a 10% phenolic resin solution at a mass ratio of 1:5 for 20 min, then removed and centrifuged, and then dried at 80℃ for 30 min to cure the resin layer. The dip-coating / drying cycle was repeated 3 times to obtain the polymer-coated carbon microspheres. The polymer-coated carbon microspheres were placed in a nitrogen atmosphere furnace and heated to 400℃ (carbonization temperature) at a rate of 5℃ / min. The temperature was maintained for 2 hours, and then cooled to room temperature in the furnace and removed. Carbon microspheres were added to silicate sol at a mass ratio of 1:10 and stirred at 50 rpm for 30 min; filtered and dried at 80 °C for 2 h; then cured at 200 °C for 1 h under nitrogen atmosphere with a heating rate of 2 °C / min to obtain composite coated carbon microspheres with a total thickness of 0.05 μm. The silicate sol is prepared by mixing tetraethoxysilane with an equal volume of ethanol, adding deionized water in a molar ratio of 1:8 to tetraethoxysilane and hydrochloric acid accounting for 1% of the mass of tetraethoxysilane, and adjusting the pH to 8 by adding 0.5 mol / L ammonia water dropwise, followed by stirring and hydrolysis at 40°C for 2 hours.

[0029] Example 2: The difference between this example and Example 1 is that 3-(trimethoxysilyl)methacrylate accounts for 2.2% of the mass of dried manganese oxide.

[0030] Example 3: The difference between this example and Example 1 is that 3-(trimethoxysilyl)methacrylate accounts for 3.0% of the mass of dried manganese oxide.

[0031] Determination of activation index (calculated based on the buoyancy of particles in water, used to characterize the degree of hydrophobic modification of particle surface): Take a certain mass (m1) of manganese oxide particles, place them in a beaker containing 50 mL of deionized water, stir with a glass rod for 2 minutes, and then let stand for 10 minutes; observe carefully, the hydrophobically modified particles will float on the water surface, while the unmodified hydrophilic particles will sink to the bottom. Carefully remove all the floating parts, dry them and weigh them (m2); Activation index (%) = (m2 / m1) × 100%.

[0032] Determination of loss on ignition: Take a clean crucible and ignite it in a muffle furnace at a temperature above 900℃ to constant weight. After cooling, weigh it (W1). Weigh a certain amount (m3) of manganese oxide powder into the crucible and record the total weight (W2). Place the crucible in the muffle furnace and gradually raise the temperature from room temperature to 900℃ (to completely decompose and burn off the organic layer on the surface), and keep it at this temperature for 1-2 hours. After cooling to room temperature, weigh it (W3). Loss on ignition (%) = [(W2-W3) / (W2-W1)] × 100%.

[0033] Table 1 Performance data of manganese oxide particles

[0034] As the silane dosage increased from 1.5% to 2.2%, the activation index significantly improved from 85.5% to 98.2%. This indicates that a dosage of 1.5% is insufficient to completely coat all manganese oxide particle surfaces, leaving some surfaces in an unmodified hydrophilic state. When the dosage reached 2.2%, a complete monomolecular coating layer was essentially formed, achieving a better hydrophobic modification effect. Further increasing the dosage to 3.0% only slightly increased the activation index to 98.5%, indicating that the improvement effect was no longer significant. This suggests that a dosage of 2.2% was close to saturation coating, and excessive silane addition did not significantly improve the coating integrity.

[0035] The loss on ignition data were positively correlated with the amount of silane used, increasing from 0.48% (1.5%) to 0.71% (2.2%) and 0.95% (3.0%), which directly proves that as the amount of feed increases, the amount of organic matter successfully grafted onto the particle surface also increases.

[0036] Example 4: A preparation process for a special protective slag for Mn13 high wear-resistant steel, comprising the following steps: S1.1 Weigh the following raw materials in parts by weight: 40 parts by weight of pre-melted refining slag, 8 parts by weight of composite coated carbon microspheres, 15 parts by weight of manganese oxide particles, 10 parts by weight of sodium carbonate, 5 parts by weight of borax and 5 parts by weight of bentonite. S1.2. Pour the pre-melted refining slag, sodium carbonate, borax, manganese oxide particles and bentonite into a double cone mixer, turn on the mixer and mix at 20 rpm for 45 minutes to obtain a mixed dry powder matrix. S1.3 Transfer the mixed dry powder matrix to a shear mixer. Add composite coated carbon microspheres while stirring at 20 rpm, and then mix for 20 minutes. At the same time, add 5-8% of the total mass of the mixed powder to the mixed powder through a spray device and mix until the material is semi-wet. Then, granulate the mixed wet material through a granulator through a 20-mesh sieve to obtain wet granules. S1.4 Spread the wet granules evenly on the drying tray, then place them in a hot air circulating drying oven and dry them at 120℃ for 3 hours to reduce the moisture content of the granules to below 0.5%; transfer the dried granules into an atmosphere heat treatment furnace, and heat them to 350℃ at a nitrogen flow rate of 2L / min with a nitrogen protection rate of 5℃ / min and hold for 2 hours. S1.5 After the heat preservation is completed, the furnace is cooled to below 60°C and then removed under nitrogen atmosphere protection; a 100-mesh double-layer vibrating screen is used for sieving to obtain special protective slag for Mn13 high wear-resistant steel.

[0037] The preparation process of manganese oxide particles is as follows: 2.2% of the mass of dried manganese oxide propyl 3-(trimethoxysilyl)methacrylate was added to ethanol to obtain a 2% mass concentration propyl 3-(trimethoxysilyl)methacrylate solution. A 3-(trimethoxysilyl)methacrylate propyl ester solution was added dropwise to an ethanol / water medium with a total volume of 5 times its volume, while stirring at 400 rpm at room temperature for 30 min to obtain a pre-hydrolyzed 3-(trimethoxysilyl)methacrylate propyl ester solution. Dry manganese oxide was added to a pre-hydrolyzed propyl 3-(trimethoxysilyl)methacrylate solution at a mass ratio of 1:2. The mixture was stirred at 500 rpm at 40°C for 3 hours. After the reaction was completed, the mixture was allowed to stand at 60°C for 60 minutes to obtain a reaction slurry. The reaction slurry was filtered, washed twice with ethanol, and then rinsed once with deionized water. The filter cake was placed in a vacuum drying oven and dried at 80°C for 12 hours to constant weight to obtain dried powder. The dried powder was placed in a nitrogen atmosphere at a flow rate of 2 L / min and heated to 280°C at a rate of 10°C / min. The temperature was maintained for 1 hour, then cooled to room temperature and removed. The powder was then sieved through a 150-mesh sieve to obtain manganese oxide particles.

[0038] The preparation process of composite coated carbon microspheres is as follows: The carbon microspheres were immersed in a 10% phenolic resin solution at a mass ratio of 1:10 for 20 min, then removed and centrifuged, and then dried at 120℃ for 60 min to cure the resin layer. The dip-coating / drying cycle was repeated 3 times to obtain the polymer-coated carbon microspheres. The polymer-coated carbon microspheres were placed in a nitrogen atmosphere furnace and heated to 400℃ (carbonization temperature) at 10℃ / min (a preliminary carbonization transition layer is formed at 400℃). The temperature was maintained for 2 hours, and then cooled to room temperature with the furnace and removed. Carbon microspheres were added to silicate sol at a mass ratio of 1:20 and stirred at 100 rpm for 30 min; filtered and dried at 120 °C for 6 h; then cured at 300 °C for 1 h under nitrogen atmosphere with a temperature increase of 5 °C / min to obtain composite coated carbon microspheres with a total thickness of 1 μm. The silicate sol is prepared by mixing tetraethoxysilane with an equal volume of ethanol, adding deionized water at a molar ratio of 1:12 to tetraethoxysilane and hydrochloric acid at 2% of the mass of tetraethoxysilane, and adjusting the pH to 9 by adding 0.5 mol / L ammonia water dropwise, followed by stirring and hydrolysis at 60°C for 4 hours.

[0039] Example 5: The difference between this example and Example 4 is that the phenolic resin solution has a mass concentration of 15%.

[0040] Example 6: The difference between this example and Example 4 is that the phenolic resin solution has a mass concentration of 20%.

[0041] Example 7: The difference between this example and Example 4 is that the carbonization temperature is 500°C.

[0042] Example 8: The difference between this example and Example 4 is that the carbonization temperature is 600°C.

[0043] Determination of combustion delay performance: Take 5-10g of composite-coated carbon microspheres and place them in the constant temperature zone of a tube furnace. Heat the sample from room temperature to 1300℃ at a rate of 5℃ / min, and hold at this temperature for 30min. Simultaneously, continuously introduce a mixed gas consisting of 60% nitrogen, 20% carbon dioxide, and 20% carbon monoxide, with a total flow rate controlled at 1L / min. Record the curve of sample mass change with temperature. Compare this curve with that of uncoated original carbon microspheres. Determine the initial oxidation temperature (usually expressed as T5% at 5% weight loss) and the temperature corresponding to the maximum oxidation rate (T5%). max ).

[0044] Table 2 Performance data of composite coated carbon microspheres

[0045] Comparing Examples 4, 5, and 6, at a fixed carbonization temperature, as the concentration of phenolic resin increased from 10% to 20%, the initial oxidation temperature and the maximum weight loss temperature gradually increased, while the loss on ignition gradually decreased.

[0046] A higher concentration of phenolic resin means a thicker polymer layer coating the surface of the carbon microspheres after each dip-coating-curing process; after carbonization at the same temperature, a thicker carbon shell and a more complete silicate ceramic layer are formed; the thicker physical barrier can more effectively isolate oxygen and heat, thus exhibiting superior delayed combustion and antioxidant properties.

[0047] Compared with Examples 4, 7, and 8, at a fixed phenolic concentration, as the carbonization temperature increased from 400°C to 600°C, the initial oxidation temperature and the maximum weight loss temperature increased significantly, while the loss on ignition decreased sharply (from 85.5% to 28.5%).

[0048] Incomplete carbonization at 400℃ results in a disordered, porous, and poorly dense carbon layer structure, thus weakening the barrier effect and reducing its antioxidant and flame-retardant capabilities. Carbonization at 500℃ is more complete, forming a denser and more stable glassy carbon structure, which significantly improves the barrier efficiency. Carbonization at 600℃ can make the carbon layer structure more ordered and enhance its antioxidant properties, but excessively high temperatures cause the carbon microsphere core to be etched, resulting in a significant decrease in the loss on ignition rate.

[0049] Example 9: A process for preparing a special protective slag for Mn13 high wear-resistant steel, comprising the following steps: S1.1 Weigh the following raw materials in parts by weight: 32 parts by weight of pre-melted refining slag, 3 parts by weight of composite coated carbon microspheres, 10 parts by weight of manganese oxide particles, 8 parts by weight of sodium carbonate, 4 parts by weight of borax and 4 parts by weight of bentonite. S1.2. Pour the pre-melted refining slag, sodium carbonate, borax, manganese oxide particles and bentonite into a double cone mixer, turn on the mixer and mix at 20 rpm for 45 minutes to obtain a mixed dry powder matrix. S1.3 Transfer the mixed dry powder matrix to a shear mixer and add composite coated carbon microspheres while stirring at 20 rpm. Mix and grind for another 20 minutes. At the same time, add 6% of the total mass of the mixed powder to the mixed powder through a spray device and mix until the material is semi-wet. Then, granulate the mixed wet material through a granulator through a 15-mesh sieve to obtain wet granules. S1.4 Spread the wet granules evenly on the drying tray, then place them in a hot air circulating drying oven and dry them at 110℃ for 3 hours to reduce the moisture content of the granules to below 0.5%; transfer the dried granules into an atmosphere heat treatment furnace, and heat them to 300℃ at a nitrogen flow rate of 2L / min with a nitrogen protection rate of 4℃ / min and hold for 2 hours. S1.5 After the heat preservation is completed, the furnace is cooled to below 60°C and then removed under nitrogen atmosphere protection; a 50-mesh double-layer vibrating screen is used for sieving to obtain special protective slag for Mn13 high wear-resistant steel.

[0050] The preparation process of manganese oxide particles is as follows: 2.2% of the mass of dried manganese oxide propyl 3-(trimethoxysilyl)methacrylate was added to ethanol to obtain a 1.5% mass concentration propyl 3-(trimethoxysilyl)methacrylate solution. A 3-(trimethoxysilyl)methacrylate propyl ester solution was added dropwise to an ethanol / water medium with a total volume of 4 times its volume, while stirring at 300 rpm at room temperature for 30 min to obtain a pre-hydrolyzed 3-(trimethoxysilyl)methacrylate propyl ester solution. Dry manganese oxide was added to a pre-hydrolyzed propyl 3-(trimethoxysilyl)methacrylate solution at a mass ratio of 1:2. The mixture was stirred at 600 rpm at 40°C for 3 hours. After the reaction was completed, the mixture was allowed to stand at 60°C for 60 minutes to obtain a reaction slurry. The reaction slurry was filtered, washed twice with ethanol, and then rinsed once with deionized water. The filter cake was placed in a vacuum drying oven and dried at 80°C for 2 hours to constant weight to obtain dried powder. The dried powder was placed in a nitrogen atmosphere at a flow rate of 1 L / min and heated to 280°C at a rate of 5°C / min. The temperature was maintained for 1 hour, then cooled to room temperature and removed. The powder was then sieved through a 100-mesh sieve to obtain manganese oxide particles.

[0051] The preparation process of composite coated carbon microspheres is as follows: The carbon microspheres were immersed in a 15% phenolic resin solution at a mass ratio of 1:8 for 20 min, then removed and centrifuged, and then dried at 100℃ for 60 min to cure the resin layer. The dip-coating / drying cycle was repeated 3 times to obtain the polymer-coated carbon microspheres. The polymer-coated carbon microspheres were placed in a nitrogen atmosphere furnace, heated to 500°C at a rate of 5°C / min, held at that temperature for 2 hours, and then cooled to room temperature in the furnace before being removed. Carbon microspheres were added to silicate sol at a mass ratio of 1:15 and stirred at 100 rpm for 30 min. The mixture was filtered and dried at 100 °C for 6 h. The mixture was then cured at 300 °C for 1 h under a nitrogen atmosphere by heating at 2 °C / min to obtain composite coated carbon microspheres with a total thickness of 1 μm. The silicate sol is prepared by mixing tetraethoxysilane with an equal volume of ethanol, adding deionized water in a molar ratio of 1:10 to tetraethoxysilane and hydrochloric acid accounting for 2% of the mass of tetraethoxysilane, and adjusting the pH to 9 by adding 0.5 mol / L ammonia water dropwise, followed by stirring and hydrolysis at 60°C for 4 hours.

[0052] Example 10: The difference between this example and Example 9 is that 5 parts by weight of composite coated carbon microspheres are used.

[0053] Example 11: The difference between this example and Example 9 is that 8 parts by weight of composite coated carbon microspheres are used.

[0054] Determination of melting temperature: Press the protective slag powder into a standard cylindrical cake (e.g., Φ3×3mm), place it in the furnace of a high-temperature microscope, and heat it at a standard rate (e.g., 10℃ / min) under a certain atmosphere (usually air); record the temperature when the sample height becomes half of the original height (hemispherical point temperature, T hemisphere is often defined as melting temperature).

[0055] Viscosity determination: The protective slag is melted at high temperature in a platinum crucible. A platinum rotor is immersed in the molten slag and rotated at a fixed speed. The torque on the rotor is measured, which is proportional to the viscosity of the molten slag. The temperature is controlled by a program, and the viscosity is continuously measured and plotted as a function of temperature to obtain the viscosity at 1300℃.

[0056] Surface crack index determination: Cut a sample from the continuously cast billet and perform hot acid washing (usually using 50% hydrochloric acid, heated to 70-80℃, soaking for 20-40 minutes). After cleaning, observe the surface for defects such as transverse cracks, longitudinal cracks, and depressions with the naked eye or a low magnifying glass. Classify the cracks according to their severity (such as width and depth): crack incidence >20% is high, 10-20% is medium, and <10% is low.

[0057] Determination of total oxygen content: The extracted steel sample should be solidified into a spherical or ingot shape with a diameter of about 5 mm, ensuring that there are no shrinkage cavities, cracks and surface oxidation inside the sample; place the sample in a beaker containing acetone or anhydrous ethanol and clean it in an ultrasonic cleaner for 5-10 minutes to remove oil and dust; after taking it out, dry it quickly with hot air and wait for testing immediately or store it in a desiccator; use an oxygen and nitrogen analyzer for determination; the computer inside the instrument automatically calculates the oxygen content based on the standard curve, sample weight and detection signal, and displays the result in ppm.

[0058] Table 3. Special protective slag for Mn13 high wear-resistant steel and performance data of Mn13 high wear-resistant steel.

[0059] As the content of carbon microspheres in the composite coating increases from 3 parts to 8 parts, the melting temperature of the protective slag increases and the high-temperature viscosity increases.

[0060] Example 9 (3 parts): Insufficient carbon content resulted in a weak inhibitory effect on the melting of the matrix, thus leading to a lower melting temperature and lower viscosity. Example 10 (5 parts): Moderate carbon content effectively delayed the melting of the matrix, forming a stable structure and allowing heat to be transferred smoothly downwards, thus exhibiting a suitable viscosity. Example 11 (8 parts): Excessive carbon content excessively inhibited melting. Although the resulting liquid slag layer had high viscosity and good stability, the melting process was excessively delayed.

[0061] Example 10 (5 samples) exhibited better surface quality (lowest crack index), which was attributed to the formation of a stable, appropriately viscous liquid slag film that provided uniform and continuous lubrication between the billet and the copper plate, and ensured uniform heat flux density, thus avoiding thermal stress cracks caused by uneven cooling.

[0062] Example 9 (3 copies): Due to poor melting control, the liquid slag layer was unstable or uneven in thickness, resulting in poor lubrication and uneven heat transfer, thus the risk of cracking was high.

[0063] Example 11 (8 portions): The excessively high viscosity resulted in a thin or discontinuous liquid slag film, which reduced the lubrication capacity and increased the frictional resistance during billet pulling. At the same time, because the billet shell cooled faster, the thermal stress increased, resulting in a surface crack index that was better than that of Example 9 but worse than that of Example 10.

[0064] The higher carbon content enhances the reducing atmosphere and inhibits secondary oxidation, thereby reducing the total oxygen content of the molten steel; at the same time, the increased viscosity leads to changes in lubricity, but plays a dominant role in improving the purity of the molten steel.

[0065] Example 12: A preparation process for a special protective slag for Mn13 high wear-resistant steel, comprising the following steps: S1.1 Weigh the following raw materials in parts by weight: 32 parts by weight of pre-melted refining slag, 5 parts by weight of composite coated carbon microspheres, 5 parts by weight of manganese oxide particles, 8 parts by weight of sodium carbonate, 4 parts by weight of borax and 4 parts by weight of bentonite. S1.2. Pour the pre-melted refining slag, sodium carbonate, borax, manganese oxide particles and bentonite into a double cone mixer, turn on the mixer and mix at 20 rpm for 45 minutes to obtain a mixed dry powder matrix. S1.3 Transfer the mixed dry powder matrix to a shear mixer and add composite coated carbon microspheres while stirring at 20 rpm. Mix and grind for another 20 minutes. At the same time, add 6% of the total mass of the mixed powder to the mixed powder through a spray device and mix until the material is semi-wet. Then, granulate the mixed wet material through a granulator through a 15-mesh sieve to obtain wet granules. S1.4 Spread the wet granules evenly on the drying tray, then place them in a hot air circulating drying oven and dry them at 110℃ for 3 hours to reduce the moisture content of the granules to below 0.5%; transfer the dried granules into an atmosphere heat treatment furnace, and heat them to 300℃ at a nitrogen flow rate of 2L / min with a nitrogen protection rate of 4℃ / min and hold for 2 hours. S1.5 After the heat preservation is completed, the furnace is cooled to below 60°C and then removed under nitrogen atmosphere protection; a 50-mesh double-layer vibrating screen is used for sieving to obtain special protective slag for Mn13 high wear-resistant steel.

[0066] The preparation process of manganese oxide particles is as follows: 2.2% of the mass of dried manganese oxide propyl 3-(trimethoxysilyl)methacrylate was added to ethanol to obtain a 1.5% mass concentration propyl 3-(trimethoxysilyl)methacrylate solution. A 3-(trimethoxysilyl)methacrylate propyl ester solution was added dropwise to an ethanol / water medium with a total volume of 4 times its volume, while stirring at 300 rpm at room temperature for 30 min to obtain a pre-hydrolyzed 3-(trimethoxysilyl)methacrylate propyl ester solution. Dry manganese oxide was added to a pre-hydrolyzed propyl 3-(trimethoxysilyl)methacrylate solution at a mass ratio of 1:2. The mixture was stirred at 600 rpm at 40°C for 3 hours. After the reaction was completed, the mixture was allowed to stand at 60°C for 60 minutes to obtain a reaction slurry. The reaction slurry was filtered, washed twice with ethanol, and then rinsed once with deionized water. The filter cake was placed in a vacuum drying oven and dried at 80°C for 2 hours to constant weight to obtain dried powder. The dried powder was placed in a nitrogen atmosphere at a flow rate of 1 L / min and heated to 280°C at a rate of 5°C / min. The temperature was maintained for 1 hour, then cooled to room temperature and removed. The powder was then sieved through a 100-mesh sieve to obtain manganese oxide particles.

[0067] The preparation process of composite coated carbon microspheres is as follows: The carbon microspheres were immersed in a 15% phenolic resin solution at a mass ratio of 1:8 for 20 min, then removed and centrifuged, and then dried at 100℃ for 60 min to cure the resin layer. The dip-coating / drying cycle was repeated 3 times to obtain the polymer-coated carbon microspheres. The polymer-coated carbon microspheres were placed in a nitrogen atmosphere furnace, heated to 500°C at a rate of 5°C / min, held at that temperature for 2 hours, and then cooled to room temperature in the furnace before being removed. Carbon microspheres were added to silicate sol at a mass ratio of 1:15 and stirred at 100 rpm for 30 min. The mixture was filtered and dried at 100 °C for 6 h. The mixture was then cured at 300 °C for 1 h under a nitrogen atmosphere by heating at 2 °C / min to obtain composite coated carbon microspheres with a total thickness of 1 μm. The silicate sol is prepared by mixing tetraethoxysilane with an equal volume of ethanol, adding deionized water in a molar ratio of 1:10 to tetraethoxysilane and hydrochloric acid accounting for 2% of the mass of tetraethoxysilane, and adjusting the pH to 9 by adding 0.5 mol / L ammonia water dropwise, followed by stirring and hydrolysis at 60°C for 4 hours.

[0068] Example 13: The difference between this example and Example 12 is that 10 parts by weight of manganese oxide particles are used.

[0069] Example 14: The difference between this example and Example 12 is that the manganese oxide particles are 15 parts by weight.

[0070] Table 4. Special protective slag for Mn13 high wear-resistant steel and performance data of Mn13 high wear-resistant steel.

[0071] As the content of manganese oxide particles increased from 5 parts to 15 parts, the melting temperature of the protective slag decreased significantly, and the viscosity at 1300℃ decreased significantly.

[0072] In silicate slag networks, MnO has cations (Mn... 2+ MnO can disrupt the silicon-oxygen (Si-O) network structure and weaken the network's connectivity. The more MnO added, the stronger the destructive effect on the silicate network, leading to a decrease in the structural complexity of the melt, which allows it to melt at a lower temperature (lower melting point) and has better fluidity after melting (lower viscosity).

[0073] As the manganese oxide content increases, the total oxygen content of the steel continues to decrease, from 38 ppm to 27 ppm.

[0074] A large amount of MnO is added to the protective slag beforehand to make its composition closer to the state after absorbing inclusions such as Al2O3 and SiO2 that float to the surface of the molten steel.

[0075] When a protective slag with high MnO content (Examples 13, 14) comes into contact with molten steel, because the slag system is pre-saturated with MnO, its key physicochemical properties (such as basicity, melting point, and viscosity) change less after absorbing acidic inclusions such as Al2O3 and SiO2 floating in the molten steel. This allows it to remain within its efficient inclusion absorption performance window for a longer period. This stability significantly improves the efficiency and total capacity of the protective slag in purifying molten steel and absorbing inclusions, thus significantly increasing the purity of the molten steel.

[0076] The crack index showed a trend of first decreasing and then increasing with the increase of manganese oxide content. The crack index of Example 13 (10 parts) was still lower than the baseline, but that of Example 14 (15 parts) was significantly increased.

[0077] Example 13 (10 portions): Moderate viscosity and a lower melting point facilitate the formation of a vitrified slag film, resulting in good lubrication and therefore a low crack index.

[0078] Example 14 (15 samples): The excessively low melting point and viscosity had a negative impact; the extremely low viscosity resulted in an excessively thin liquid slag layer, which could not provide uniform and continuous lubrication and increased friction; more importantly, the excessively high MnO content led to a significant decrease in its crystallization temperature, and the slag film mainly existed in the glassy form. The thermal conductivity of the glassy slag film is much higher than that of the crystalline slag film, which increased the heat flow density from the billet shell to the crystallizer, resulting in an excessively fast cooling rate, uneven billet shell thickness, and thus generating large thermal stress, which ultimately induced transverse cracks on the surface.

[0079] Based on the above measurements and comprehensive evaluation, Example 13 was selected as the optimal example. Comparative Example 1: The difference between this example and Example 13 is that no composite coated carbon microspheres were added.

[0080] Comparative Example 2: The difference between this example and Example 13 is that no silicate ceramic membrane was added, and the carbon microspheres were directly impregnated and coated with phenolic resin solution.

[0081] Comparative Example 3: The difference between this example and Example 13 is that no manganese oxide particles were added.

[0082] Comparative Example 4: The difference between this example and Example 13 is that manganese oxide particles were not added, but manganese oxide was added directly.

[0083] Table 5. Special protective slag for Mn13 high wear-resistant steel and performance data of Mn13 high wear-resistant steel.

[0084] The protective slag of Comparative Example 1 (without composite coated carbon microspheres) has an extremely low melting temperature and viscosity, resulting in an extremely high crack index and a relatively high total oxygen content.

[0085] The lack of composite coated carbon microspheres means the loss of core control over the melting process of the protective slag; the protective slag matrix melts too early and too quickly, and cannot form a stable structure; resulting in a thick but unstable liquid slag layer, extremely uneven lubrication and heat transfer, which easily leads to surface cracks in the billet; at the same time, the reducing atmosphere is insufficient, the absorption efficiency of secondary oxidation and inclusions decreases, and the purity of molten steel deteriorates.

[0086] Comparative Example 2 (carbon microspheres without silicate ceramic film) had inferior performance in all aspects compared to Example 13, especially with a higher crack index.

[0087] Carbon microspheres without an outer silicate ceramic film exhibit combustion behavior similar to traditional carbon materials (such as carbon black), resulting in premature combustion failure and an inability to continuously control melting throughout the process. This leads to inconsistent melting behavior of the protective slag, reduced lubrication capacity in the later stages, and increased risk of cracking. Its performance is superior to Comparative Example 1 but significantly inferior to Example 13, demonstrating the synergistic effect of the composite structure.

[0088] The protective slag of Comparative Example 3 (without added manganese oxide particles) has a high melting point, high viscosity, and a sharp increase in total oxygen content, but a low surface crack index.

[0089] Without manganese oxide particles, the protective slag loses its pre-saturation ability for MnO. When it comes into contact with MnO inclusions floating on the molten steel, its composition and properties (melting point, viscosity) undergo drastic changes, deteriorating its ability to absorb subsequent inclusions and resulting in poor steel purity (total oxygen content 58 ppm). However, its crack index is low because the high viscosity protective slag inhibits slag flow and forms a thicker slag film, providing a good lubrication barrier in the short term, so cracks do not increase significantly. However, this high viscosity state will significantly reduce the inclusion absorption efficiency, leading to a deterioration in the cleanliness of the molten steel.

[0090] Comparative Example 4 (with added unmodified manganese oxide) had a higher total oxygen content (37 ppm) than Comparative Example 3 but lower than Example 13 (30 ppm) and a higher crack index.

[0091] Ordinary manganese oxide powder is prone to sintering and agglomeration at high temperatures, resulting in uneven distribution in the protective slag. The resulting local high MnO areas can cause uneven slag properties, affecting the uniformity of lubrication and increasing the risk of cracking. Its ability to absorb inclusions is also inferior to that of surface-modified manganese oxide particles due to its easy sintering and poor compatibility.

[0092] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A special protective slag for Mn13 high wear-resistant steel, characterized in that, The raw materials include: pre-melted refining slag, composite coated carbon microspheres, manganese oxide particles, sodium carbonate, borax, and bentonite; The composite coated carbon microspheres are prepared by first impregnating and coating the carbon microspheres with a phenolic resin solution and then curing them, followed by low-temperature carbonization to form an amorphous carbon barrier layer, and finally depositing a silicate ceramic film on its outer surface using a sol-gel method. Manganese oxide particles are prepared by forming an organic-inorganic composite film on the surface of propyl 3-(trimethoxysilyl)methacrylate.

2. The protective slag for Mn13 high wear-resistant steel according to claim 1, characterized in that, The composition includes 25-40 parts by weight of pre-melted refining slag, 3-8 parts by weight of composite coated carbon microspheres, 5-15 parts by weight of manganese oxide particles, 5-10 parts by weight of sodium carbonate, 2-5 parts by weight of borax, and 3-5 parts by weight of bentonite.

3. The special protective slag for Mn13 high wear-resistant steel according to claim 2, characterized in that, The preparation process of the manganese oxide particles is as follows: Add 1.5-3.0% of 3-(trimethoxysilyl)methacrylate by mass of dried manganese oxide to ethanol to obtain a 1-2% 3-(trimethoxysilyl)methacrylate solution. Add 3-(trimethoxysilyl)methacrylate solution dropwise to 3-5 times its total volume of ethanol / water medium, while stirring at 300-400 rpm at room temperature for 20-30 min to obtain a pre-hydrolyzed 3-(trimethoxysilyl)methacrylate solution. Dry manganese oxide was added to a pre-hydrolyzed propyl 3-(trimethoxysilyl)methacrylate solution at a mass ratio of 1:1-2. The mixture was stirred at 500-1000 rpm at 25-40℃ for 2-3 hours. After the reaction was completed, the mixture was allowed to stand at 40-60℃ for 30-60 minutes to obtain a reaction slurry. The reaction slurry was filtered, washed twice with ethanol, and then rinsed once with deionized water. The filter cake was placed in a vacuum drying oven and dried at 80-100℃ for 6-12 hours until constant weight was obtained to obtain dried powder. The dried powder was placed in a nitrogen atmosphere at a flow rate of 0.5-2 L / min and heated to 250-300℃ at a rate of 5-10℃ / min. The temperature was maintained for 1 hour, then cooled to room temperature and removed. The powder was then sieved through an 80-150 mesh sieve to obtain manganese oxide particles.

4. The special protective slag for Mn13 high wear-resistant steel according to claim 3, characterized in that, The ethanol / water medium is obtained by mixing ethanol and deionized water at a volume ratio of 4:1 at room temperature, and adjusting the pH to 4.0-4.5 with 0.1 mol / L acetic acid.

5. The special protective slag for Mn13 high wear-resistant steel according to claim 2, characterized in that, The preparation process of the composite coated carbon microspheres is as follows: The carbon microspheres were immersed in a 10-20% phenolic resin solution at a mass ratio of 1:5-10 for 5-20 minutes, then removed and centrifuged. The resin layer was then dried at 80-120℃ for 30-60 minutes to solidify the resin layer. The dip-coating / drying cycle was repeated 1-3 times to obtain the polymer-coated carbon microspheres. The polymer-coated carbon microspheres were placed in a nitrogen atmosphere furnace and heated to 400-600℃ at a rate of 5-10℃ / min, held at that temperature for 0.5-2h, and then cooled to room temperature in the furnace and removed. Carbon microspheres were added to silicate sol at a mass ratio of 1:10-20 and stirred at 50-100 rpm for 10-30 min. The mixture was filtered and dried at 80-120℃ for 2-6 h. It was then cured at 200-300℃ for 0.5-1 h under a nitrogen atmosphere by heating at 2-5℃ / min to obtain composite coated carbon microspheres with a total thickness of 0.05-1 μm.

6. The special protective slag for Mn13 high wear-resistant steel according to claim 5, characterized in that, The silicate sol is obtained by mixing tetraethoxysilane with an equal volume of ethanol, adding deionized water in a molar ratio of 1:8-12 to tetraethoxysilane and hydrochloric acid accounting for 1-2% of the mass of tetraethoxysilane, and adjusting the pH to 8-9 by adding 0.5 mol / L ammonia water dropwise, and then stirring and hydrolyzing at 40-60℃ for 2-4 hours.

7. The special protective slag for Mn13 high wear-resistant steel according to claim 2, characterized in that, The preparation process of the special protective slag for Mn13 high wear-resistant steel is as follows: S1.1 Weigh the following raw materials in parts by weight: 25-40 parts by weight of pre-melted refining slag, 3-8 parts by weight of composite coated carbon microspheres, 5-15 parts by weight of manganese oxide particles, 5-10 parts by weight of sodium carbonate, 2-5 parts by weight of borax and 3-5 parts by weight of bentonite. S1.

2. Pour the pre-melted refining slag, sodium carbonate, borax, manganese oxide particles and bentonite into a double cone mixer, turn on the mixer and mix at a speed of 15-20 rpm for 30-45 minutes to obtain a mixed dry powder matrix. S1.3 Transfer the mixed dry powder matrix to a shear mixer. Add composite coated carbon microspheres while stirring at 15-20 rpm, and then mix for 15-20 minutes. At the same time, add deionized water to the mixed powder through a spray device and mix until the material is semi-wet. Then, granulate the mixed wet material through a granulator through a 10-20 mesh sieve to obtain wet granules. S1.4 Spread the wet granules evenly on the drying tray, then place them in a hot air circulating drying oven and dry them at 110-120℃ for 2-3 hours to reduce the moisture content of the granules to below 0.5%; transfer the dried granules into an atmosphere heat treatment furnace, and heat them to 280-350℃ under nitrogen protection and keep them at that temperature for 1-2 hours. S1.5 After the heat preservation is completed, the furnace is cooled to below 60°C and then removed under nitrogen atmosphere protection; a 40-100 mesh double-layer vibrating screen is used for sieving to obtain special protective slag for Mn13 high wear-resistant steel.

8. The special protective slag for Mn13 high wear-resistant steel according to claim 7, characterized in that, In step S1.3, the amount of deionized water added is 5-8% of the total mass of the mixed powder.

9. The special protective slag for Mn13 high wear-resistant steel according to claim 7, characterized in that, In S1.4, the nitrogen flow rate is 1-2 L / min.

10. The special protective slag for Mn13 high wear-resistant steel according to claim 7, characterized in that, In S1.4, the heating rate is 3-5℃ / min.

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