A silicon nitride bonded silicon carbide refractory with added metallic titanium for blast furnaces, a method of preparation and use

Abstract

The application discloses a kind of silicon nitride bonded silicon carbide refractory materials with added metal titanium for blast furnace, preparation method and application, belong to refractory material technical field.The application introduces metal titanium powder into traditional silicon nitride bonded silicon carbide raw material system, and titanium-silicon alloy is generated by using metal titanium and metal silicon to react at high temperature, on the one hand, effectively break the silicon dioxide passivation film on the surface of metal silicon, without the multi-stage ladder heat preservation of traditional process, significantly shorten the sintering cycle, reduce energy consumption, on the other hand, titanium-silicon alloy occurs micro-reaction along the boundary of silicon carbide aggregate, generates titanium carbide to strengthen the interface bonding of aggregate and matrix, and the nitrogenated product of titanium and the aforementioned reaction product are mutually solid-solved to form Ti (C, N, O) multi-component solid solution, and form a complex combination phase with silicon nitride.The refractory material prepared by the application has excellent normal temperature pressure resistance, high temperature bending resistance and slag erosion resistance, and is particularly suitable for key parts such as blast furnace belly and waist.

Description

Technical Field

[0001] This invention relates to the field of refractory materials technology, and more specifically to a silicon nitride-bonded silicon carbide refractory material with added titanium for blast furnaces, its preparation method, and its application. Background Technology

[0002] Silicon nitride-bonded silicon carbide refractories, with their excellent high-temperature strength, thermal shock resistance, and slag erosion resistance, are widely used in key parts of blast furnaces such as tapholes and furnace linings, making them a core refractory material in the blast furnace ironmaking field. Traditional silicon nitride-bonded silicon carbide products use silicon carbide as aggregate and metallic silicon powder as the nitriding matrix raw material. They are fired at high temperatures in a nitrogen atmosphere, and the silicon nitride bonding phase is generated through the nitridation of metallic silicon, achieving a dense bond between the aggregate and the matrix.

[0003] However, in the current industrial production and application processes, this system faces many technical bottlenecks: Firstly, the dense silica passivation film naturally present on the surface of metallic silicon powder severely hinders the contact between nitrogen gas and elemental silicon, resulting in sluggish silicon nitridation kinetics. The sintering process must employ a multi-stage, stepped temperature control system, typically requiring prolonged holding at temperatures such as 600℃ and 1000℃ to overcome the obstruction of the nitriding reaction by the SiO2 passivation film on the metallic silicon powder surface. This not only leads to sintering cycles lasting tens of hours and high energy consumption but also easily results in incomplete nitriding within the blank, high levels of residual free silicon, and black-core cracking, thus limiting the yield of the finished product.

[0004] Secondly, the interfacial bonding strength of the pure silicon nitride bonding phase is limited, and a weak bonding interface is easily formed between SiC aggregate and matrix. Under the conditions of high-temperature slag and iron erosion and thermal shock alternation in blast furnaces, phenomena such as interface debonding, peeling, and intensified erosion and penetration are prone to occur, significantly shortening the service life of the material.

[0005] Third, conventional silicon nitride-combined silicon carbide systems have limited toughening and corrosion resistance modification methods. Although the industry has attempted to introduce exogenous additives for modification, these additives can easily disrupt the stability of the original sintering process or cause problems such as metal phase flow, billet deformation, and phase agglomeration, making it difficult to balance process compatibility and performance improvement.

[0006] To address the aforementioned shortcomings, while there are related technologies in the industry that improve the performance of refractory materials by adding titanium compounds, most of these technologies focus on titanium oxide reduction nitriding and direct nitriding of titanium alloys to prepare TiN single phase. They do not involve the synergistic modification mechanism of in-situ generation of titanium-silicon alloys from metallic titanium and metallic silicon, nor do they achieve integrated control of "breaking the silicon passivation film, accelerating nitriding, strengthening the interface, and in-situ generation of multi-component solid solutions".

[0007] Therefore, developing a process-compatible, highly efficient nitriding, tough interface, and excellent erosion-resistant silicon nitride-bonded silicon carbide refractory material preparation technology is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0008] In view of this, the present invention provides a silicon nitride-bonded silicon carbide refractory material with added metallic titanium for blast furnaces, a preparation method and application. The method achieves integrated control of nitriding efficiency improvement, interfacial bonding strengthening and material comprehensive performance optimization by introducing metallic titanium, without significantly altering the original firing process framework.

[0009] To solve the above-mentioned technical problems, this application adopts the following technical solution: The primary objective of this application is to provide a method for preparing a silicon nitride-bonded silicon carbide refractory material with added metallic titanium for blast furnaces, comprising the following steps: (1) Raw material preparation: Prepare the following raw materials by mass percentage, the total of which is 100%: Silicon carbide: 69-80%; Silicon metal powder, particle size ≤0.075mm: 9~20%; Titanium powder, particle size ≤0.044mm: 1~8%; Composite sintering aid: 1-3%; And, a binder comprising 1.5 to 5% of the total mass of the above raw materials; The silicon carbide is composed of a blend of silicon carbide particles of the following sizes, and the percentage of each size of silicon carbide in the total mass of the raw materials is as follows: 3-1mm coarse-grained silicon carbide: 28-31%; 1-0 mm medium-particle silicon carbide: 18-22%; 0.088~1mm fine-particle silicon carbide: 14~16%; ≤0.088mm silicon carbide ultrafine powder: 9~11%; The composite sintering aid is composed of alumina micro powder, aluminum nitride and boric anhydride in a mass ratio of 2:1:1. (2) Mixing and molding: The 3-1 mm coarse silicon carbide particles and 1-0 mm medium silicon carbide particles are dry-mixed for 3-5 minutes to achieve initial dispersion of the aggregate. Then, 0.088-1 mm fine silicon carbide particles, ≤0.088 mm ultrafine silicon carbide powder, metallic silicon powder, metallic titanium powder, and composite sintering aid are added sequentially while stirring. After all the powders are added, dry-mixing continues for 5-20 minutes to ensure that all powder materials are evenly coated on the surface of the aggregate. Then, a binder is added and wet-mixed for 5-30 minutes to form a uniform and plastic clay. The clay is then pressed into shape to obtain brick blanks. (3) Drying treatment: The brick blanks are dried in sections: 1) Raise the room temperature to 60℃ at a rate of 3℃ / min, and dry at a constant temperature of 60℃ for 8 hours to remove free moisture from the surface of the green body; 2) The temperature is raised from 60℃ to 110℃ at a rate of 2℃ / min, and then kept at 110℃ for 24 hours to completely remove adsorbed and bound water from the interior of the green body. 3) After drying, allow the kiln to cool naturally to room temperature, then remove and set aside. The moisture content of the dried brick blanks should be ≤0.5%; (4) Nitriding sintering: The dried brick blanks are then nitrided and sintered under a continuous atmosphere of high-purity nitrogen, as detailed below: 1) The room temperature is raised to 600℃ at a rate of 4℃ / min to remove residual water vapor and volatile substances; 2) The temperature is raised from 600℃ to 1000℃ at a rate of 3℃ / min to complete the initial solid-phase shrinkage of the billet; 3) The temperature is raised from 1000℃ to 1450℃ at a rate of 2℃ / min, gradually triggering the in-situ titanium-silicon reaction and nitriding reaction; 4) Hold at 1450℃ for 2-8 hours to ensure full nitriding of metallic silicon, in-situ formation of titanium-silicon alloy, and uniform precipitation of solid solution; then cool down with the furnace to obtain the final product.

[0010] This method improves upon the traditional Si3N4-SiC material preparation process, achieving complete nitriding without the need for multi-stage heat treatment during sintering, thus facilitating industrial production. The resulting refractory material retains the excellent properties of traditional Si3N4-SiC materials, but the bonding phase changes from a single Si3N4 bond to a Si3N4 / Ti(C,N,O) composite bond. Its room-temperature compressive strength, high-temperature flexural strength, and resistance to molten iron and slag erosion are all impressive, demonstrating excellent overall performance, making it particularly suitable for modern large-scale blast furnaces operating under harsh conditions.

[0011] As a preferred technical solution, the binder in step (1) is an aqueous solution of calcium lignosulfonate or a thermoplastic phenolic resin.

[0012] As a preferred technical solution, the pressing pressure in step (2) is 100-200MPa, the single pressure holding is 3-5s, and the pressing is repeated 3-5 times to expel the air inside the blank and obtain a brick blank with a dense structure and regular shape.

[0013] As a preferred technical solution, when the brick blanks in step (4) are placed under the protection of a continuous atmosphere of high-purity nitrogen, a 20-30mm air gap is reserved between the blanks; the high-purity nitrogen is continuously circulated and the flow rate is controlled at 8-15m³ / h, and the purity of the high-purity nitrogen is ≥99.99%.

[0014] Another object of this application is to provide: silicon nitride-bonded silicon carbide refractory material for blast furnaces with added metallic titanium, prepared by the above method.

[0015] Another object of this application is to provide: the application of the refractory material in a blast furnace, wherein the refractory material is used in at least one of the following parts: the belly of the blast furnace, the waist of the furnace, and the lower part of the furnace body.

[0016] Another object of this application is to provide the application of the refractory material in the preparation of blast furnace lining components.

[0017] Another object of this application is to provide a blast furnace lining component made of the aforementioned refractory material.

[0018] Another object of this application is to provide a blast furnace including the aforementioned blast furnace lining components, or including the aforementioned refractory material.

[0019] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: The core technical principle and beneficial effects of introducing metallic titanium in this invention are as follows: (1) Formation of Ti(C,N,O) multi-component solid solution to achieve toughening and corrosion resistance In this invention, titanium powder undergoes a series of reactions under a high-temperature nitriding atmosphere: First, metallic titanium preferentially reacts with metallic silicon to form a Ti-Si alloy. The Ti in this alloy further reacts with SiO2 on the surface of metallic silicon (Ti + SiO2 → TiO2 + Si), breaking the passivation film. Simultaneously, Ti reacts with the SiC aggregate boundary (SiC + Ti → TiC + Si). Furthermore, Ti reacts with N2 to form TiN. The TiO2, TiC, and TiN generated by these reactions dissolve into each other at high temperature, forming a Ti(C,N,O) multi-component solid solution.

[0020] The metallic silicon powder itself, as well as the active silicon released by the above reaction, undergoes a nitriding reaction under a nitrogen atmosphere: 3Si + 2N2 → Si3N4, forming a silicon nitride bonded phase.

[0021] This solid solution, together with Si3N4, forms a complex phase, which exhibits superior hardness, toughness, and thermal stability compared to a single Si3N4 phase, significantly enhancing the material's resistance to erosion and thermal shock.

[0022] (2) Remove the silicon passivation film to achieve rapid nitriding without multi-stage heat preservation. The Ti-Si alloy formed by the preferential reaction of titanium and silicon can effectively break the SiO2 passivation film on the surface of silicon powder, allowing nitrogen gas to directly contact elemental silicon and significantly accelerating the nitriding reaction kinetics. Therefore, this invention eliminates the need for the multi-stage stepped heating process required in traditional methods to overcome the passivation film barrier; complete nitriding of silicon can be achieved using continuous and uniform heating, significantly shortening the sintering cycle and reducing energy consumption.

[0023] (3) Enhance the interfacial bonding between SiC aggregate and matrix The micro-reaction (SiC+Ti→TiC+Si) along the SiC aggregate boundary in the Ti-Si alloy generates TiC, which forms a chemically bonded transition layer between the aggregate and the matrix, transforming the traditional physical bonding into chemical bonding. This significantly improves the interfacial bonding strength and effectively suppresses interfacial debonding and peeling during service.

[0024] (4) The entire reaction is in solid state to avoid the flow and segregation of the metal phase. Ti-Si alloys have high melting points (TiSi2 melting point is 1540℃, Ti5Si3 melting point is 2130℃), and can maintain a solid state without flowing within the material's firing temperature range. Furthermore, the formation of Ti-Si alloys transforms the "melt-on-molten nitriding" of metallic silicon into "solid-phase nitriding," avoiding the agglomeration and segregation of the molten silicon and ensuring the uniformity of the nitriding reaction and the density of the green body.

[0025] (5) Significantly improved overall performance The refractory material prepared by this invention has a bonding phase that is changed from the traditional single Si3N4 bonding to a Si3N4 / Ti(C,N,O) complex bonding. The room temperature compressive strength, high temperature flexural strength and slag erosion resistance are significantly improved compared with the traditional material, making it particularly suitable for critical parts with harsh working conditions such as the blast furnace belly and waist. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0027] Figure 1 Example 1: XPS results of titanium element in sample.

[0028] Figure 2 Here is an electron microscope image of the sample from Example 1. Detailed Implementation

[0029] 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. Example 1

[0030] A method for preparing a silicon nitride-bonded silicon carbide refractory material with added metallic titanium for blast furnaces includes the following steps:

[0031] (1) Raw material preparation (by mass percentage, total 100%): Table 1 Raw material preparation for Example 1

[0032] The composite sintering aid is composed of alumina micro powder, aluminum nitride, and boron anhydride in a mass ratio of 2:1:1.

[0033] Binder: 50wt% calcium lignosulfonate aqueous solution, plus 3.0%.

[0034] (2) Mixing and molding: Coarse silicon carbide particles of 3-1 mm and medium silicon carbide particles of 1-0 mm are put into a high-pressure mixer and dry-mixed for 4 min; then fine silicon carbide particles of 0.088-1 mm, ultrafine silicon carbide powder of ≤0.088 mm, metallic silicon powder, metallic titanium powder and composite sintering aid are added in sequence while stirring. After all the additions are completed, dry-mix for 12 min; then add a 50 wt% calcium lignosulfonate aqueous solution and wet-mix for 7 min to form a uniform and plastic clay. The brick is molded using a fully automatic hydraulic brick press with a molding pressure of 150 MPa, a single pressure holding time of 4 s, and 4 reciprocating presses to expel the air inside the brick body, resulting in a dense and regular brick blank.

[0035] (3) Drying treatment: The room temperature is raised to 60℃, the heating rate is 3℃ / min, and the temperature is kept constant at 60℃ for 8 hours; the temperature is raised to 110℃, the heating rate is 2℃ / min, and the temperature is kept constant at 110℃ for 24 hours; after drying, the temperature is naturally cooled to room temperature with the kiln, and the blank is taken out for use. The moisture content of the blank after drying is 0.3%.

[0036] (4) Nitriding sintering: The dried brick blanks are placed in the nitriding firing kiln, with a 25mm air gap between the blanks. High-purity nitrogen (99.995%) is used at a flow rate of 12m³ / h, and the pressure inside the kiln is controlled to be 15mm water column higher than the atmospheric pressure outside the kiln, maintaining a slightly positive pressure state. Continuous heating regime: from room temperature to 600℃, heating rate 4℃ / min; from 600℃ to 1000℃, heating rate 3℃ / min; from 1000℃ to 1450℃, heating rate 2℃ / min; hold at 1450℃ for 5h. Cool down with the furnace to obtain the final product.

[0037] X-ray photoelectron spectroscopy (XPS) analysis was performed on the refractory material sample prepared in Example 1, and the results are as follows: Figure 1 As shown. Figure 1 The image shows the high-resolution XPS spectrum of the Ti 2p orbital of the titanium element in the sample of Example 1.

[0038] from Figure 1 It can be seen that the main binding energy peak of the Ti 2p3 / 2 orbital of titanium is located in the range of 454–459 eV, corresponding to titanium oxides (TiO, Ti2O3, TiO2) as well as TiC and TiN. Meanwhile, no characteristic peaks of metallic titanium appear near 454 eV. Figure 2 SEM images and EDS results confirmed that titanium mainly exists in the form of Ti(C,N,O) multi-component solid solution.

[0039] The above results are consistent with the technical principle described in this invention: after titanium powder reacts with silicon metal to form a Ti-Si alloy during nitriding sintering, it then reacts with N2 to form TiN. At the same time, Ti reacts with SiC at the boundary to form TiC, and Ti reacts with SiO2 to form titanium oxides (TiO, Ti2O3, TiO2). These products dissolve in each other at high temperature to form a Ti(C,N,O) multi-component solid solution. Figure 1 The absence of obvious residual titanium signals indicates that the titanium element has completely reacted and is uniformly distributed in the material in the form of a Ti(C,N,O) multi-component solid solution. Example 2

[0040] A method for preparing a silicon nitride-bonded silicon carbide refractory material with added metallic titanium for blast furnaces includes the following steps:

[0041] (1) Raw material preparation (by mass percentage, total 100%): Table 2 Raw material preparation for Example 2

[0042] The composition of the composite sintering aid is the same as in Example 1.

[0043] Binder: 70% thermoplastic phenolic resin with an additional 2.5%.

[0044] (2) Mixing and molding: Coarse silicon carbide particles of 3-1 mm and medium silicon carbide particles of 1-0 mm are added to a high-pressure mixer and dry-mixed for 5 min; then fine silicon carbide particles of 0.088-1 mm, ultrafine silicon carbide powder of ≤0.088 mm, metallic silicon powder, metallic titanium powder and composite sintering aid are added in sequence while stirring. After all the additions are completed, dry-mix for another 15 min; then thermoplastic phenolic resin with a solid content of 70% is added and wet-mixed for 6 min to form a uniform and plastic clay. The brick is molded using a fully automatic hydraulic brick press with a molding pressure of 200 MPa, a single pressure holding time of 5 s, and repeated pressing 5 times to expel the air inside the brick body, resulting in a dense and regular brick blank.

[0045] (3) Drying treatment: The room temperature is raised to 60℃, the heating rate is 3℃ / min, and the temperature is kept constant at 60℃ for 8 hours; the temperature is raised to 110℃, the heating rate is 2℃ / min, and the temperature is kept constant at 110℃ for 24 hours; after drying, the temperature is naturally cooled to room temperature with the kiln, and the blank is taken out for use. The moisture content of the blank after drying is 0.2%.

[0046] (4) Nitriding sintering: The dried brick blanks are placed in the nitriding firing kiln, with a 20mm air gap between the blanks. High-purity nitrogen (99.995%) is used at a flow rate of 15m³ / h, and the pressure inside the kiln is controlled to be 10mm higher than the atmospheric pressure outside the kiln, maintaining a slightly positive pressure state. Continuous heating regime: from room temperature to 600℃, heating rate 4℃ / min; from 600℃ to 1000℃, heating rate 3℃ / min; from 1000℃ to 1450℃, heating rate 2℃ / min; hold at 1450℃ for 8 hours. Cool down with the furnace to obtain the final product. Example 3

[0047] A method for preparing a silicon nitride-bonded silicon carbide refractory material with added metallic titanium for blast furnaces includes the following steps:

[0048] (1) Raw material preparation (by mass percentage, total 100%): Table 3 Raw material preparation for Example 3

[0049] The composition of the composite sintering aid is the same as in Example 1.

[0050] Binder: 50wt% calcium lignosulfonate aqueous solution, plus 1.5%.

[0051] (2) Mixing and molding: Coarse silicon carbide particles of 3-1 mm and medium silicon carbide particles of 1-0 mm are put into a high-pressure mixer and dry-mixed for 3 min; then fine silicon carbide particles of 0.088-1 mm, ultrafine silicon carbide powder of ≤0.088 mm, metallic silicon powder, metallic titanium powder and composite sintering aid are added in sequence while stirring. After all the additions are completed, dry-mix for another 8 min; then add a 50 wt% calcium lignosulfonate aqueous solution and wet-mix for 5 min to form a uniform and plastic clay. The brick is molded using a fully automatic hydraulic brick press with a molding pressure of 100 MPa, a single pressure holding time of 3 s, and repeated pressing 3 times to expel the air inside the brick body, resulting in a dense and regular brick blank.

[0052] (3) Drying treatment: The room temperature is raised to 60℃, the heating rate is 3℃ / min, and the temperature is kept constant at 60℃ for 8 hours; the temperature is raised to 110℃, the heating rate is 2℃ / min, and the temperature is kept constant at 110℃ for 24 hours; after drying, the temperature is naturally cooled to room temperature with the kiln, and the blank is taken out for use. The moisture content of the blank after drying is 0.4%.

[0053] (4) Nitriding sintering: The dried brick blanks are placed in the nitriding firing kiln, with a 30mm air gap between the blanks. High-purity nitrogen with a purity of 99.99% is used at a flow rate of 8m³ / h. The pressure inside the kiln is controlled to be 20mm higher than the atmospheric pressure outside the kiln, maintaining a slightly positive pressure state. Continuous heating regime: from room temperature to 600℃, the heating rate is 4℃ / min; from 600℃ to 1000℃, the heating rate is 3℃ / min; from 1000℃ to 1450℃, the heating rate is 2℃ / min; hold at 1450℃ for 2 hours, then cool down with the furnace to obtain the final product.

[0054] Comparative Example 1 (No titanium added, traditional multi-segment insulation process)

[0055] A method for preparing a silicon nitride-bonded silicon carbide refractory material with added metallic titanium for blast furnaces includes the following steps:

[0056] (1) Raw material preparation (by mass percentage, total 100%): Table 4 Raw material preparation for Comparative Example 1

[0057] The composition of the composite sintering aid is the same as in Example 1.

[0058] Binder: 50wt% calcium lignosulfonate aqueous solution, plus 3.0%.

[0059] (2) Add 3-1 mm coarse silicon carbide particles and 1-0 mm medium silicon carbide particles to a high-pressure mixer and dry mix for 4 min; then add 0.088-1 mm fine silicon carbide particles, ≤0.088 mm ultrafine silicon carbide powder, metallic silicon powder and composite sintering aid in sequence, stirring while adding. After all the additions are complete, continue to dry mix for 12 min; then add a 50 wt% calcium lignosulfonate aqueous solution and wet mix for 7 min to form a uniform and plastic clay. Use a fully automatic hydraulic brick press to form the bricks. The forming pressure is 150 MPa, the pressure is held for 4 seconds at a time, and the bricks are pressed back and forth 4 times to remove the air inside the brick body and obtain a dense and regular brick body.

[0060] (3) Drying treatment: The room temperature is raised to 60℃, the heating rate is 3℃ / min, and the temperature is kept constant at 60℃ for 8 hours; the temperature is raised to 110℃, the heating rate is 2℃ / min, and the temperature is kept constant at 110℃ for 24 hours; after drying, the temperature is naturally cooled to room temperature with the kiln and then taken out for use.

[0061] (4) Nitriding sintering: The nitriding sintering process employs a traditional multi-stage heat preservation process: 99.995% high-purity nitrogen gas at a flow rate of 12 m³ / h; heating from room temperature to 600℃ at a rate of 4℃ / min, holding at 600℃ for 2 hours; heating from 600℃ to 1000℃ at a rate of 3℃ / min, holding at 1000℃ for 3 hours; heating from 1000℃ to 1450℃ at a rate of 2℃ / min, holding at 1450℃ for 8 hours; cooling down with the furnace yields the final product.

[0062] Performance testing: The performance of the refractory material prepared in Comparative Example 1 was compared with that in Examples 1-3, and the results are as follows: Table 5 Properties of refractory materials prepared from different groups

[0063] Results analysis: As can be seen from the above comparison, the refractory materials prepared in each embodiment of the present invention are significantly superior to Comparative Example 1 (without added titanium) in terms of room temperature compressive strength, high temperature flexural strength, density, and slag erosion resistance. Among them, Example 2 has the best overall performance, with its room temperature compressive strength increasing by 93.2% compared to Comparative Example 1, its high temperature flexural strength increasing by 120.5%, and its slag erosion resistance depth decreasing by 73.5%.

[0064] From the perspective of firing process, the present invention adopts a continuous uniform heating system, which eliminates the need for multi-stage stepped heat preservation in traditional processes, shortens the firing cycle by about 30-40%, reduces energy consumption by about 25-35%, and significantly reduces production costs.

[0065] Thermal shock resistance test:

[0066] The refractory materials prepared in Examples 1-3 and Comparative Example 1 were subjected to air-cooled thermal shock cyclic testing at 1100℃ (temperature difference 1000℃). The number of cycles in which the sample showed obvious cracks or a strength loss of ≥30% was taken as the number of thermal shock resistance cycles. Table 6 Results of thermal shock resistance test

[0067] Results analysis: The thermal shock resistance of the embodiments of the present invention is significantly better than that of Comparative Example 1. It is speculated that the possible reason is that the complex phase formed by Si3N4 and Ti(C,N,O) can effectively suppress crack propagation under thermal stress.

[0068] High-temperature volume stability test:

[0069] The refractory materials prepared in Examples 1-3 and Comparative Example 1 were held at 1500℃ for 3 hours, and the linear shrinkage rate after firing was tested. Table 7 High-Temperature Volume Stability Test

[0070] Results Analysis: Negative values ​​indicate shrinkage. The high-temperature volume stability of this embodiment is better than that of Comparative Example 1, indicating that the formation of Ti(C,N,O) solid solution effectively suppresses high-temperature shrinkage.

[0071] Industrial applicability

[0072] The preparation method provided by this invention has good process compatibility and can be directly implemented on the basis of existing silicon nitride-bonded silicon carbide refractory material production lines without large-scale equipment modifications. The resulting refractory material products have excellent performance and are particularly suitable for critical parts such as the blast furnace belly and waist, where stringent requirements for high-temperature strength, thermal shock resistance, and slag erosion resistance are placed, thus possessing broad market application prospects.

[0073] Advantages of this invention over the prior art For the first time, a synergistic modification mechanism for the in-situ generation of titanium-silicon alloys using metallic titanium and metallic silicon was proposed, achieving integrated regulation of "breaking the silicon passivation film, accelerating nitriding, strengthening the interface, and generating multi-component solid solutions in situ". It eliminates the need for multi-stage heat preservation, a process that eliminates the need for traditional methods, shortens the firing cycle by more than 30%, and reduces energy consumption by more than 25%. The Ti(C,N,O) / Si3N4 composite phase was generated, and the overall performance of the material was significantly better than that of the traditional Si3N4 single-bonded material. The entire process involves solid-state reactions, resulting in good process stability and a high product qualification rate.

[0074] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0075] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a silicon nitride-bonded silicon carbide refractory material with added titanium for blast furnaces, characterized in that, Includes the following steps: (1) Raw material preparation: Prepare the following raw materials by mass percentage, the total of which is 100%: Silicon carbide: 69-80%; Silicon metal powder, particle size ≤0.075mm: 9~20%; Titanium powder, particle size ≤0.044mm: 1~8%; Composite sintering aid: 1-3%; And, a binder comprising 1.5 to 5% of the total mass of the above raw materials; The silicon carbide is composed of a blend of silicon carbide particles of the following sizes, and the percentage of each size of silicon carbide in the total mass of the raw materials is as follows: 3-1mm coarse-grained silicon carbide: 28-31%; 1-0 mm medium-particle silicon carbide: 18-22%; 0.088~1mm fine-particle silicon carbide: 14~16%; ≤0.088mm silicon carbide ultrafine powder: 9~11%; The composite sintering aid is composed of alumina micro powder, aluminum nitride and boric anhydride in a mass ratio of 2:1:

1. (2) Mixing and molding: The 3-1 mm coarse silicon carbide particles and 1-0 mm medium silicon carbide particles are dry-mixed for 3-5 minutes; then, 0.088-1 mm fine silicon carbide particles, ≤0.088 mm ultrafine silicon carbide powder, metallic silicon powder, metallic titanium powder, and composite sintering aid are added sequentially while stirring. After all the particles are added, dry-mixing continues for 5-20 minutes; then, a binder is added, and wet-mixing is carried out for 5-30 minutes to form a uniform and plastic clay; the clay is then pressed into shape to obtain a brick blank. (3) Drying treatment: The brick blanks are dried in sections: 1) Raise the room temperature to 60℃ at a rate of 3℃ / min, and dry at a constant temperature of 60℃ for 8 hours; 2) The temperature is raised from 60℃ to 110℃ at a rate of 2℃ / min, and then kept at 110℃ for 24 hours. 3) After drying, allow the kiln to cool naturally to room temperature, then remove and set aside. The moisture content of the dried brick blanks should be ≤0.5%; (4) Nitriding sintering: The dried brick blanks are then nitrided and sintered under a continuous atmosphere of high-purity nitrogen, as detailed below: 1) The room temperature is raised to 600℃ at a rate of 4℃ / min; 2) Heating from 600℃ to 1000℃ at a rate of 3℃ / min; 3) Heating from 1000℃ to 1450℃ at a rate of 2℃ / min; 4) Hold at 1450℃ for 2-8 hours; then cool down with the furnace to obtain the final product.

2. The preparation method according to claim 1, characterized in that, The binder in step (1) is an aqueous solution of calcium lignosulfonate or a thermoplastic phenolic resin.

3. The preparation method according to claim 1, characterized in that, The pressing pressure in step (2) is 100-200 MPa, the pressure is held for 3-5 seconds at a time, and the pressing is repeated 3-5 times.

4. The preparation method according to claim 1, characterized in that, In step (4), when the brick blanks are placed under the protection of a continuous atmosphere of high-purity nitrogen, a 20-30mm air gap is reserved between the blanks; the high-purity nitrogen is continuously circulated and introduced, with a flow rate controlled at 8-15m³ / h, and the purity of the high-purity nitrogen is ≥99.99%.

5. A silicon nitride-bonded silicon carbide refractory material for blast furnaces with added metallic titanium, prepared by the method according to any one of claims 1 to 4.

6. The application of the refractory material according to claim 5 in a blast furnace, characterized in that, The refractory material is used in at least one of the following parts: the belly of the blast furnace, the waist of the furnace, and the lower part of the furnace body.

7. The application of the refractory material according to claim 5 in the preparation of blast furnace lining components.

8. A blast furnace lining component, characterized in that, Made from the refractory material as described in claim 5.

9. A blast furnace, characterized in that, It includes the blast furnace lining component as described in claim 8, or the refractory material as described in claim 5.

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