Thermal shock resistant furnace lining refractory and method of making same

Abstract

This invention provides a thermal shock resistant furnace lining refractory material and its preparation method, belonging to the technical field of magnesium oxide and ceramic refractory materials. The material includes magnesium ceramic aggregate, self-healing ceramic powder, lightly calcined magnesium oxide powder, ceramic binder, hexagonal boron nitride, mullite powder, and cerium oxide. The magnesium ceramic aggregate is prepared by coating recalcined magnesium oxide with magnesium aluminum spinel and yttrium-stabilized zirconium oxide through spinning pitch bonding and sintering. The self-healing ceramic powder is prepared by reacting aluminum-magnesium alloy powder, wall material, and ammonia curing agent; the wall material contains cordierite powder, mullite powder, and tetraethyl orthosilicate. The ceramic binder is formulated with ceramicized aluminum phosphate solution, silane coupling agent, and modified resin. The ceramicized aluminum phosphate solution is formulated with phosphoric acid aqueous solution, aluminum hydroxide, and nano-cordierite. The modified resin is prepared by reacting thermosetting liquid phenolic resin, diisopropyl linoleate, and tert-butyl hydrogen peroxide aqueous solution. The components work together to construct a gradient framework, a self-healing system, a full-temperature-range bonding, and a toughening network system.

Description

Technical Field

[0001] This invention belongs to the technical field of magnesium oxide and ceramic refractory materials, specifically relating to a thermal shock resistant furnace lining refractory material and its preparation method. Background Technology

[0002] Furnaces are core equipment in metallurgical and chemical material production. As a critical component of furnaces, the furnace lining must withstand harsh conditions such as high temperatures exceeding 1000℃, frequent temperature fluctuations, and erosion and washing by molten materials. Thermal shock damage caused by sudden temperature rises and falls is the primary cause of furnace lining failure. Traditional furnace lining refractory materials mainly include three categories: masonry bricks, castables, and ramming mixes. Masonry bricks, with their high strength, were once widely used, but their joints easily become stress concentration points, leading to cracking and detachment under thermal shock cycles. Castables are convenient to construct and have good integrity, but their high bulk density and thermal conductivity make it difficult to release thermal stress generated by temperature changes, limiting their thermal shock resistance. In contrast, ramming mixes, formed by manual or mechanical compaction, require no complex curing processes, can adapt to irregular furnace structures, and have a uniform pore distribution. At high temperatures, their micropores can buffer thermal stress, making them a preferred material that balances construction flexibility and thermal shock resistance.

[0003] Early ramming mixes primarily used natural minerals such as clay and high-alumina materials, bonded with siliceous or aluminous binders. While inexpensive, they were prone to phase transformation at high temperatures, leading to excessive volume change, poor thermal shock resistance, and a tendency to develop noticeable cracks. With the increasing scale and efficiency of high-temperature industries, furnace operating temperatures have risen above 1400℃, and the rates of heating and cooling have accelerated significantly. The thermal shock resistance of traditional ramming mixes can no longer meet the requirements. To address this technical bottleneck, the industry has gradually begun research on thermal shock resistance modification. On one hand, by optimizing particle size distribution and adopting a composite particle skeleton design, a loose and porous microstructure is constructed, reducing thermal conductivity and the coefficient of thermal expansion. On the other hand, thermal shock resistant components such as magnesium oxide, zirconium oxide, and silicon carbide are introduced, utilizing their low expansion characteristics or phase transformation effects to absorb thermal stress. Simultaneously, the binder system has been upgraded from traditional clay and water glass binders to phosphoric acid and resin binders, improving high-temperature bonding strength and structural stability.

[0004] Although existing modification technologies have made some progress, they still have many shortcomings: while porous structures improve thermal shock resistance, they reduce the material's wear and corrosion resistance; some binders are prone to decomposition at high temperatures, generating gas and resulting in a loose furnace lining structure. Therefore, developing ramming mixes with both high thermal shock resistance and strong wear and corrosion resistance has become a research hotspot and technical challenge in the field of refractory materials. Summary of the Invention

[0005] To address the problems of poor wear and erosion resistance due to the porous structure of existing furnace lining refractory materials, the difficulty in balancing thermal shock resistance and wear and erosion resistance, and the loosening of the furnace lining structure due to the binder at high temperatures, this invention provides a thermal shock resistant furnace lining refractory material and its preparation method. The material is prepared using magnesia-ceramic aggregate, self-healing ceramic powder, lightly calcined magnesia powder, ceramic binder, hexagonal boron nitride, mullite powder, and cerium oxide. By constructing a gradient skeleton, a self-healing system, full-temperature bonding, and a toughening network, a multi-faceted synergistic technical system is established, solving the technical bottlenecks of traditional furnace lining refractory materials, such as the difficulty in balancing thermal shock resistance and wear and erosion resistance, and the tendency for the structure to become loose at high temperatures. The specific technical solution is as follows:

[0006] A thermal shock resistant furnace lining refractory material comprises the following raw materials in parts by weight: 45-50 parts of magnesia-ceramic aggregate, 12-18 parts of self-healing ceramic powder, 10-15 parts of lightly calcined magnesia powder, 8-14 parts of ceramic binder, 3-8 parts of hexagonal boron nitride, 2-5 parts of mullite powder, and 1-2 parts of cerium oxide.

[0007] The magnesium ceramic aggregate is obtained by bonding and coating recalcined magnesium oxide with magnesium aluminum spinel and yttrium stabilized zirconium oxide through spinning pitch, and sintering at 600℃~650℃ and 1450℃~1550℃; the mass ratio of recalcined magnesium oxide, spinning pitch, magnesium aluminum spinel and yttrium stabilized zirconium oxide is 100:(3~5):(4~6):(1~2);

[0008] The self-healing ceramic powder is obtained by reacting aluminum-magnesium alloy powder, wall material, and ammonia curing agent in a mass ratio of (50-55):(200-220):(15-20); the wall material is prepared by mixing cordierite powder, mullite powder, tetraethyl orthosilicate, and anhydrous ethanol in a mass ratio of (23-27):(19-25):(50-60):(150-200) and adjusting the pH to 2.8-3.2.

[0009] The ceramic binder is prepared by mixing ceramicized aluminum phosphate solution, silane coupling agent KH-560 and modified resin in a mass ratio of (100-120):(5-7):(60-80); the ceramicized aluminum phosphate solution is prepared by mixing phosphoric acid aqueous solution, aluminum hydroxide and nano cordierite in a mass ratio of (100-120):(40-45):(5-8); the modified resin is prepared by reacting thermosetting liquid phenolic resin, diisopropyl linoleate and tert-butyl hydrogen peroxide aqueous solution in a mass ratio of 100:(8-12):(1.5-2.5).

[0010] The preparation method of the magnesium ceramic aggregate mentioned above includes the following steps: according to the mass ratio of reburned magnesium oxide: spinning pitch: magnesium aluminum spinel: yttrium stabilized zirconium oxide = 100: (3~5): (4~6): (1~2), first mix magnesium aluminum spinel and yttrium stabilized zirconium oxide evenly, add spinning pitch and mix evenly to obtain modified material; add modified material to reburned magnesium oxide, mix and coat at 350℃~400℃ and 60rpm~80rpm for 1.5h~2h, sinter at 600℃~650℃ for 30min~50min, sinter at 1450℃~1550℃ for 1h~1.5h, cool to room temperature, disperse, and sieve to obtain magnesium ceramic aggregate with a particle size range of 0.2mm~6mm.

[0011] In the above-mentioned method for preparing magnesium ceramic aggregate, the gradation of the reburned magnesium oxide is as follows: 2mm < particle size ≤ 6mm accounts for 55wt% to 60wt%, and 0.2mm < particle size ≤ 2mm accounts for 40wt% to 45wt%; the median particle size of the spinning pitch is below 3μm; the median particle size of the magnesium aluminum spinel is 2μm to 8μm; the median particle size of the yttrium stabilized zirconium oxide is below 3μm; and the particle size range of the magnesium ceramic aggregate is 0.2mm to 6mm.

[0012] The preparation method of the self-healing ceramic powder in the above raw materials includes the following steps: Cordierite powder, mullite powder, tetraethyl orthosilicate and anhydrous ethanol are mixed in a mass ratio of (23-27):(19-25):(50-60):(150-200), and the pH is adjusted to 2.8-3.2 to obtain a wall material; aluminum-magnesium alloy powder is added to the wall material in a mass ratio of aluminum-magnesium alloy powder:wall material:ammonia curing agent = (50-55):(200-220):(15-20), stirred, and ammonia curing agent is added dropwise to form a microcapsule suspension; the mixture is filtered, the solid is taken, vacuum dried, dispersed, and sieved to obtain the self-healing ceramic powder.

[0013] In the above-mentioned method for preparing self-healing ceramic powder, the median particle size of the cordierite powder is 1μm to 5μm; the median particle size of the mullite powder is 1μm to 5μm; the median particle size of the aluminum-magnesium alloy powder is 20μm to 30μm; the stirring is carried out at 65℃ to 75℃ and 350rpm to 400rpm for 30min to 40min; the ammonia curing agent is 20wt% to 25wt% ammonia curing agent; and the reaction time is 2.5h to 3h.

[0014] The preparation method of the ceramic binder in the above raw materials includes the following steps: stirring according to the mass ratio of phosphoric acid aqueous solution: aluminum hydroxide: nano cordierite = (100-120): (40-45): (5-8) to obtain ceramicized aluminum phosphate solution; stirring thermosetting liquid phenolic resin and diisopropyl linoleate at 60℃-65℃ according to the mass ratio of thermosetting liquid phenolic resin: diisopropyl linoleate: tert-butyl hydroperoxide aqueous solution = 100: (8-12): (1.5-2.5), and adding tert-butyl hydroperoxide. Hydrogen peroxide aqueous solution is heated to 85℃~90℃ and stirred under nitrogen protection. After cooling, a modified resin is obtained. The silane coupling agent KH-560 is added to the ceramicized aluminum phosphate solution according to a mass ratio of (100~120):(5~7):(60~80) for the modified resin. The mixture is stirred at 60℃~65℃ and then cooled to obtain a mixture. Under nitrogen protection and stirring, the mixture is added to the modified resin, stirred continuously, and degassed under vacuum to obtain a ceramic binder.

[0015] In the above-mentioned method for preparing ceramic binders, the phosphoric acid aqueous solution is an 80wt% to 85wt% phosphoric acid aqueous solution; the tert-butyl hydrogen peroxide aqueous solution is a 65wt% to 70wt% tert-butyl hydrogen peroxide aqueous solution; and the cooling is all to 45℃ to 50℃.

[0016] In the above raw materials, the median particle size of the lightly calcined magnesium oxide powder is 20 μm to 40 μm.

[0017] In the above-mentioned raw materials, the hexagonal boron nitride is nanoscale.

[0018] In the above raw materials, the median particle size of the mullite powder is 1μm to 5μm.

[0019] In the above-mentioned raw materials, the cerium oxide is nanoscale.

[0020] The preparation method of the above-mentioned thermal shock resistant furnace lining refractory material includes the following steps: mixing magnesia ceramic aggregate and lightly calcined magnesia powder, adding a mixture of premixed self-healing ceramic powder, hexagonal boron nitride, mullite powder and cerium oxide, mixing dry, finally adding ceramic binder, mixing wet, hot tamping molding, and curing.

[0021] In the above preparation method, the hot tamping molding is performed by heating to 130℃~160℃ and tamping; the curing is performed by heating to 200℃~300℃ and holding for 2h~3h, heating to 500℃~600℃ and holding for 1h~2h, and then naturally cooling to room temperature.

[0022] The present invention provides a thermal shock resistant furnace lining refractory material and its preparation method, which have the following beneficial effects:

[0023] I. This invention's refractory material, through a multi-faceted synergistic technical system including a gradient skeleton, self-healing system, full-temperature range integration, and toughening network, solves the technical bottleneck of traditional furnace lining refractory materials, which struggle to balance thermal shock resistance and wear and erosion resistance, and are prone to high-temperature structural loosening. Its core principle is to achieve thermal stress dispersion, active repair of microcracks, and full-temperature range structural stability through raw material structure design and component synergy, adapting to extreme thermal cycling conditions and meeting the usage requirements of harsh service environments such as waste incineration rotary kilns and non-ferrous metal smelting furnaces.

[0024] II. Magnesium ceramic aggregate uses reburned magnesium oxide as the core to provide a highly alkaline and corrosion-resistant foundation, and magnesium aluminum spinel and yttrium-stabilized zirconium oxide as the outer shell. It forms a core-shell structure by pre-firing at 600℃~650℃ and high-temperature sintering at 1450℃~1550℃, which realizes gradient expansion, disperses thermal stress, and solves the core contradiction between corrosion resistance and thermal shock resistance; specific particle size distribution ensures the compactness of aggregate packing.

[0025] 3. The self-healing ceramic powder is made by encapsulating aluminum-magnesium alloy powder with cordierite-mullite composite wall material. It is then cross-linked with ammonia water curing agent to form a microcapsule structure. At high temperature, the capsule wall ruptures and releases the alloy liquid, which reacts with magnesium oxide to form a magnesium-aluminum solid solution-ceramic composite phase, realizing a closed loop of damage, repair and strengthening, and inhibiting crack propagation; the wall material itself improves the high temperature stability of the material.

[0026] IV. Modified phenolic resin utilizes the unsaturated double bonds on the diisopropyl linoleate molecular chain, grafting them into the cross-linked network of phenolic resin through a catalytic reaction to achieve polymerization and toughening. By using free radical graft copolymerization, the compatibility issue between the flexible long chain and the resin matrix is ​​resolved, resulting in superior thermal shock resistance and fracture toughness compared to the unmodified resin system.

[0027] 5. Lightly calcined magnesium oxide powder supplements the magnesium skeleton and undergoes a solid solution reaction with ceramic components to generate high-strength phases such as magnesium aluminum spinel and magnesium zirconate, which improves the material's density and alkali resistance and strengthens the stability of the skeleton structure.

[0028] VI. The ceramic binder uses ceramicized aluminum phosphate liquid to provide a high-temperature ceramic bonding base, the modified resin ensures rapid low-temperature bonding and toughness, and the silane coupling agent KH-560 improves the compatibility of the inorganic and organic interface; it achieves a full-temperature range of strength-free discontinuous bonding, including low-temperature resin bonding, medium-temperature resin carbonization, and high-temperature aluminum phosphate ceramicization, avoiding structural loosening at high temperatures.

[0029] 7. Hexagonal boron nitride forms a ceramic network, which improves the fracture toughness of the material and enhances its impact and thermal shock resistance.

[0030] 8. Mullite powder fills the micropores and is sintered together with magnesium oxide to reduce high-temperature creep rate and improve volume stability.

[0031] 9. Cerium oxide acts as a catalyst to inhibit the high-temperature grain coarsening of magnesium oxide and ceramic components, accelerates the spinelization reaction, improves self-healing efficiency, and enhances high-temperature mechanical properties.

[0032] 10. In the preparation steps, hot tamping at 130℃~160℃ ensures the density of the material; segmented curing at 200℃~300℃ and 500℃~600℃ promotes cross-linking of the binder and stability of the crystal phase, avoids structural defects caused by rapid heating, and further improves the uniformity and stability of the structure.

[0033] In summary, the core-shell structure of the magnesium-ceramic aggregate, combined with the three-dimensional network of hexagonal boron nitride and the pore-filling effect of mullite powder, forms a dense, integrated macroscopic and microscopic structure that reduces thermal conductivity, disperses thermal stress, and enhances wear and corrosion resistance. The active crack repair of the self-healing ceramic powder, the catalytic strengthening of cerium oxide, and the strong interfacial bonding of the ceramic binder synergistically inhibit crack initiation and propagation, significantly improving thermal shock cycle stability. The organic-inorganic composite system of the ceramic binder, synergistically with the high-temperature reaction of each component, achieves structural stability throughout the entire process from low-temperature molding to high-temperature service, avoiding the problems of weak low-temperature bonding and easy high-temperature failure found in traditional materials. The in-situ polymerization toughening of the modified resin synergistically with the rigid reinforcement of the ceramic phase, forming a rigid skeleton and flexible dispersed phase structure that balances strength and toughness. Detailed Implementation

[0034] The present invention will be further described below with reference to specific implementation examples, but the present invention is not limited to these embodiments.

[0035] Example 1

[0036] A thermal shock resistant furnace lining refractory material comprises the following raw materials in parts by weight: 48 parts magnesia-ceramic aggregate, 16 parts self-healing ceramic powder, 13 parts lightly calcined magnesia powder, 11 parts ceramic binder, 5 parts hexagonal boron nitride, 3 parts mullite powder, and 1.5 parts cerium oxide. The median particle size of the lightly calcined magnesia powder is 32.5 μm. The hexagonal boron nitride is nano-sized. The median particle size of the mullite powder is 3.1 μm. The cerium oxide is nano-sized.

[0037] The preparation method of magnesium ceramic aggregate includes the following steps: Magnesium aluminum spinel and yttrium stabilized zirconium oxide are mixed uniformly at a mass ratio of 100:4:5:1.5 (re-burned magnesium oxide: spinning pitch: magnesium aluminum spinel: yttrium stabilized zirconium oxide). Then, spinning pitch is added and mixed uniformly to obtain a modified material. This modified material is added to re-burned magnesium oxide and mixed and coated at 380℃ and 70 rpm for 1.5 h. Afterward, it is sintered at 620℃ for 40 min and then at 1500℃ for 1 h. The mixture is then cooled to room temperature, dispersed, and sieved to obtain magnesium ceramic aggregate with a particle size range of 0.2 mm to 6 mm. The gradation of the re-burned magnesium oxide is as follows: 58 wt% for particles 2 mm < ≤ 6 mm and 42 wt% for particles 0.2 mm < ≤ 2 mm. The median particle size of the spinning pitch is 2.6 μm. The median particle size of the magnesium aluminum spinel is 5.3 μm. The median particle size of yttrium-stabilized zirconium oxide is 1.8 μm.

[0038] The preparation method of the self-healing ceramic powder includes the following steps: Cordierite powder, mullite powder, tetraethyl orthosilicate, and anhydrous ethanol are mixed in a mass ratio of 25:21:55:180, and the pH is adjusted to 3.0 with 9wt% hydrochloric acid aqueous solution to obtain the wall material; aluminum-magnesium alloy powder is added to the wall material in a mass ratio of 53:210:18, and the mixture is stirred at 70℃ and 380rpm for 35min. 22wt% ammonia curing agent is added dropwise at a rate of 1.5mL / min, and the reaction is allowed to proceed for 2.5h to form a microcapsule suspension; the mixture is filtered, the solid is collected, vacuum dried at 100℃ for 7h, dispersed, and sieved through a 200-mesh sieve to obtain the self-healing ceramic powder. The median particle size of the cordierite powder is 3.5μm. The median particle size of the mullite powder is 4.2μm. The median particle size of the aluminum-magnesium alloy powder is 26.7μm.

[0039] The preparation method of the ceramic binder includes the following steps: A ceramicized aluminum phosphate solution is obtained by stirring at 75°C for 3.5 hours at a mass ratio of 82wt% phosphoric acid aqueous solution: aluminum hydroxide: nano cordierite = 110:42:7. A 68wt% tert-butyl hydrogen peroxide aqueous solution is prepared. Thermosetting liquid phenolic resin and diisopropyl linoleate are mixed at 62°C and 450 rpm for 40 minutes at a mass ratio of thermosetting liquid phenolic resin: diisopropyl linoleate: tert-butyl hydrogen peroxide aqueous solution = 100:11:2 to obtain a premix. The tert-butyl hydrogen peroxide aqueous solution is then added, and the mixture is heated to 88°C and stirred at 350 rpm for 2.5 hours under nitrogen protection. The mixture is then cooled to 48°C to obtain the modified resin. According to the mass ratio of ceramicized aluminum phosphate solution: silane coupling agent KH-560: modified resin = 110:6:72, silane coupling agent KH-560 was added to ceramicized aluminum phosphate solution, stirred at 62℃ and 350rpm for 1.5h, and then cooled to 48℃ to obtain a mixture; under nitrogen protection and stirring at 450rpm, the mixture was added to the modified resin, stirred continuously for 50min, and then vacuum degassed for 35min to obtain ceramic binder.

[0040] The preparation method of the above-mentioned thermal shock resistant furnace lining refractory material includes the following steps:

[0041] Magnesium ceramic aggregate and lightly calcined magnesium oxide powder were dry-mixed at 80 rpm for 18 min. A pre-mixed mixture of self-healing ceramic powder, hexagonal boron nitride, mullite powder, and cerium oxide was added and dry-mixed at 80 rpm for 16 min. Finally, ceramic binder was added and wet-mixed at 130 rpm for 25 min. The mixture was then heated to 145℃ and held for 100 min, followed by hot tamping to form a compacted density ≥ 2.8 g / cm³. 3 Heat the sample to 260℃ at a rate of 2℃ / min and hold for 2.5 hours. Then heat it to 550℃ at a rate of 4℃ / min and hold for 1.5 hours. Allow it to cool naturally to room temperature.

[0042] Example 2

[0043] A thermal shock resistant furnace lining refractory material comprises the following raw materials in parts by weight: 45 parts magnesia-ceramic aggregate, 12 parts self-healing ceramic powder, 10 parts lightly calcined magnesia powder, 8 parts ceramic binder, 3 parts hexagonal boron nitride, 2 parts mullite powder, and 1 part cerium oxide. The median particle size of the lightly calcined magnesia powder is 20 μm. The hexagonal boron nitride is nano-sized. The median particle size of the mullite powder is 5 μm. The cerium oxide is nano-sized.

[0044] The preparation method of magnesium ceramic aggregate includes the following steps: Magnesium aluminum spinel and yttrium stabilized zirconium oxide are mixed uniformly in a mass ratio of reburned magnesium oxide: spinning pitch: magnesium aluminum spinel: yttrium stabilized zirconium oxide = 100:3:6:1. Then, spinning pitch is added and mixed uniformly to obtain a modified material. This modified material is added to reburned magnesium oxide and mixed and modified at 400℃ and 60 rpm for 2 hours. Afterward, it is sintered at 600℃ for 50 minutes and then at 1450℃ for 1.5 hours. The mixture is then cooled to room temperature, dispersed, and sieved to obtain magnesium ceramic aggregate with a particle size range of 0.2 mm to 6 mm. The gradation of the reburned magnesium oxide is as follows: 55 wt% for particles 2 mm < ≤ 6 mm and 45 wt% for particles 0.2 mm < ≤ 2 mm. The median particle size of the spinning pitch is 1 μm. The median particle size of the magnesium aluminum spinel is 8 μm. The median particle size of yttrium-stabilized zirconium oxide is 3 μm.

[0045] The preparation method of the self-healing ceramic powder includes the following steps: Cordierite powder, mullite powder, tetraethyl orthosilicate, and anhydrous ethanol are mixed in a mass ratio of 23:25:50:200, and the pH is adjusted to 3.2 with an 8wt% hydrochloric acid aqueous solution to obtain the wall material; aluminum-magnesium alloy powder is added to the wall material in a mass ratio of 50:220:15, and the mixture is stirred at 75℃ and 350rpm for 40min. 25wt% ammonia curing agent is added dropwise at a rate of 1mL / min, and the reaction is allowed to proceed for 2.5h to form a microcapsule suspension; the mixture is filtered, the solid is collected, vacuum dried at 110℃ for 6h, dispersed, and sieved through a 250-mesh sieve to obtain the self-healing ceramic powder. The median particle size of the cordierite powder is 1μm. The median particle size of the mullite powder is 5μm. The median particle size of the aluminum-magnesium alloy powder is 20μm.

[0046] The preparation method of the ceramic binder includes the following steps: An 80wt% phosphoric acid aqueous solution: aluminum hydroxide: nano cordierite = 120:40:8 mass ratio is stirred at 70℃ for 4 hours to obtain a ceramicized aluminum phosphate solution. A 65wt% concentration of tert-butyl hydrogen peroxide aqueous solution is prepared; a thermosetting liquid phenolic resin: diisopropyl linoleate: tert-butyl hydrogen peroxide aqueous solution = 100:12:1.5 mass ratio is added, and the thermosetting liquid phenolic resin and diisopropyl linoleate are stirred and mixed at 65℃ and 400rpm for 45 minutes to obtain a premixed solution. The tert-butyl hydrogen peroxide aqueous solution is added, the temperature is raised to 85℃, and the reaction is carried out under nitrogen protection with stirring at 400rpm for 2 hours. The temperature is then lowered to 50℃ to obtain the modified resin. According to the mass ratio of ceramicized aluminum phosphate solution: silane coupling agent KH-560: modified resin = 100:7:60, silane coupling agent KH-560 was added to ceramicized aluminum phosphate solution, stirred at 65℃ and 300rpm for 2h, and then cooled to 45℃ to obtain a mixture; under nitrogen protection and stirring at 500rpm, the mixture was added to the modified resin, stirred continuously for 40min, and then vacuum degassed for 40min to obtain ceramic binder.

[0047] The preparation method of the above-mentioned thermal shock resistant furnace lining refractory material includes the following steps:

[0048] Magnesium ceramic aggregate and lightly calcined magnesium oxide powder were dry-mixed at 70 rpm for 20 min. A pre-mixed mixture of self-healing ceramic powder, hexagonal boron nitride, mullite powder, and cerium oxide was added and dry-mixed at 70 rpm for 20 min. Finally, ceramic binder was added and wet-mixed at 120 rpm for 30 min. The mixture was then heated to 130℃ and held for 120 min, followed by hot tamping to form a compacted density ≥ 2.8 g / cm³. 3 Heat to 300℃ at 2℃ / min and hold for 2 hours, then heat to 500℃ at 5℃ / min and hold for 2 hours, then allow to cool naturally to room temperature.

[0049] Example 3

[0050] A thermal shock resistant furnace lining refractory material comprises the following raw materials in parts by weight: 50 parts magnesia-ceramic aggregate, 18 parts self-healing ceramic powder, 15 parts lightly calcined magnesia powder, 14 parts ceramic binder, 8 parts hexagonal boron nitride, 5 parts mullite powder, and 2 parts cerium oxide. The median particle size of the lightly calcined magnesia powder is 40 μm. The hexagonal boron nitride is nano-sized. The median particle size of the mullite powder is 1 μm. The cerium oxide is nano-sized.

[0051] The preparation method of magnesium ceramic aggregate includes the following steps: Magnesium aluminum spinel and yttrium stabilized zirconium oxide are mixed uniformly in a mass ratio of reburned magnesium oxide: spinning pitch: magnesium aluminum spinel: yttrium stabilized zirconium oxide = 100:5:4:2. Then, spinning pitch is added and mixed uniformly to obtain a modified material. This modified material is added to reburned magnesium oxide and mixed and modified at 350℃ and 80 rpm for 1.5 h. Afterward, it is sintered at 650℃ for 30 min and then at 1550℃ for 1 h. The mixture is then cooled to room temperature, dispersed, and sieved to obtain magnesium ceramic aggregate with a particle size range of 0.2 mm to 6 mm. The gradation of the reburned magnesium oxide is: 60 wt% for particles 2 mm < ≤ 6 mm and 40 wt% for particles 0.2 mm < ≤ 2 mm. The median particle size of the spinning pitch is 3 μm. The median particle size of the magnesium aluminum spinel is 2 μm. The median particle size of yttrium-stabilized zirconium oxide is 1 μm.

[0052] The preparation method of the self-healing ceramic powder includes the following steps: Cordierite powder, mullite powder, tetraethyl orthosilicate, and anhydrous ethanol are mixed in a mass ratio of 27:19:60:150, and the pH is adjusted to 2.8 with a 10wt% hydrochloric acid aqueous solution to obtain the wall material; aluminum-magnesium alloy powder is added to the wall material in a mass ratio of 55:200:20, and the mixture is stirred at 65℃ and 400rpm for 30min. 20wt% ammonia curing agent is added dropwise at a rate of 2mL / min, and the mixture is reacted for 3h to form a microcapsule suspension; the mixture is filtered, the solid is collected, vacuum dried at 90℃ for 8h, dispersed, and sieved through a 200-mesh sieve to obtain the self-healing ceramic powder. The median particle size of the cordierite powder is 5μm. The median particle size of the mullite powder is 1μm. The median particle size of the aluminum-magnesium alloy powder is 30μm.

[0053] The preparation method of the ceramic binder includes the following steps: A ceramicized aluminum phosphate solution is obtained by stirring at 80℃ for 3 hours with an 85wt% phosphoric acid aqueous solution: aluminum hydroxide: nano cordierite in a mass ratio of 100:45:5. A 70wt% tert-butyl hydrogen peroxide aqueous solution is prepared. Thermosetting liquid phenolic resin and diisopropyl linoleate are mixed at 60℃ and 500rpm for 30 minutes with a mass ratio of thermosetting liquid phenolic resin: diisopropyl linoleate: tert-butyl hydrogen peroxide aqueous solution of 100:8:2.5 to obtain a premix. The tert-butyl hydrogen peroxide aqueous solution is then added, and the mixture is heated to 90℃ and stirred at 300rpm for 2.5 hours under nitrogen protection. The mixture is then cooled to 45℃ to obtain the modified resin. According to the mass ratio of ceramicized aluminum phosphate solution: silane coupling agent KH-560: modified resin = 120:5:80, silane coupling agent KH-560 was added to ceramicized aluminum phosphate solution, stirred at 60℃ and 400rpm for 1.5h, and then cooled to 50℃ to obtain a mixture; under nitrogen protection and stirring at 400rpm, the mixture was added to the modified resin, stirred continuously for 60min, and then vacuum degassed for 30min to obtain ceramic binder.

[0054] The preparation method of the above-mentioned thermal shock resistant furnace lining refractory material includes the following steps:

[0055] Magnesium ceramic aggregate and lightly calcined magnesium oxide powder were dry-mixed at 90 rpm for 15 min. A pre-mixed mixture of self-healing ceramic powder, hexagonal boron nitride, mullite powder, and cerium oxide was added and dry-mixed at 90 rpm for 15 min. Finally, ceramic binder was added and wet-mixed at 150 rpm for 20 min. The mixture was then heated to 160℃ and held for 80 min, followed by hot tamping to form a compacted density ≥ 2.8 g / cm³. 3 Heat to 200℃ at 3℃ / min and hold for 3 hours, then heat to 600℃ at 3℃ / min and hold for 1 hour, then allow to cool naturally to room temperature.

[0056] The raw materials used in the above embodiments are as follows: Lightly calcined magnesia powder is obtained by calcining magnesite (MgCO3 > 90wt%) at 900℃ for 1.5 hours. Hexagonal boron nitride is from Henan Weiying Chemical Products Co., Ltd. Mullite powder is from Lingshou County Zhoulei Mineral Products Co., Ltd., and is white mullite powder. Cerium oxide is from Hubei Daoer Ziguang Imine New Materials Co., Ltd., and is nano-grade cerium dioxide. Darkly calcined magnesite is obtained by calcining magnesite at 1800℃, with a magnesia content of over 92%. Spinning pitch is from Jining Carbon Group Co., Ltd., and is coal tar pitch-based spinning pitch. Magnesium aluminum spinel is from Henan Jinrun New Materials Co., Ltd., with a refractory temperature of over 2000℃. Yttrium stabilized zirconium oxide is from Hubei Xinrunde Chemical Co., Ltd. Cordierite powder is from Lingshou County Baifeng Mineral Products Processing Plant, and is crushed and graded to a median particle size of 1μm to 5μm. Tetraethyl orthosilicate has a purity of 99%. The aluminum-magnesium alloy powder (Al3Mg4) is sourced from Hebei Jisheng Aluminum Powder Co., Ltd. Aluminum hydroxide is sourced from Chongqing Huihan Chemical Co., Ltd. Nano-cordierite particles, with a median particle size below 120nm, are sourced from Lingshou County Baifeng Mineral Products Processing Plant. The thermosetting liquid phenolic resin is water-soluble and sourced from Jinan Dahui Chemical Technology Co., Ltd. (model 8022). Diisopropyl linoleate is sourced from Shanghai Ruidong Chemical Group Co., Ltd. The silane coupling agent KH-560 is sourced from Shandong Huanzheng Chemical Co., Ltd.

[0057] Comparative Example 1

[0058] The difference from Example 1 is that the magnesium ceramic aggregate is replaced with reburned magnesium oxide.

[0059] Comparative Example 2

[0060] The difference from Example 1 is that the magnesium ceramic aggregate is not sintered at 1500°C during preparation.

[0061] Comparative Example 3

[0062] The difference from Example 1 is that the self-healing ceramic powder was changed to 5 parts and the lightly calcined magnesium oxide powder was changed to 24 parts.

[0063] Comparative Example 4

[0064] The difference from Example 1 is that aluminum-magnesium alloy powder is used instead of self-healing ceramic powder.

[0065] Comparative Example 5

[0066] The difference from Example 1 is that no ammonia curing agent is added in the preparation of the self-healing ceramic powder.

[0067] Comparative Example 6

[0068] The difference from Example 1 is that the ceramic binder is replaced by ceramicized aluminum phosphate liquid.

[0069] Comparative Example 7

[0070] The difference from Example 1 is that no silane coupling agent KH-560 is added in the preparation of the ceramic binder.

[0071] Comparative Example 8

[0072] The difference from Example 1 is that, in the preparation of the ceramic binder, the modified resin is replaced by a thermosetting liquid phenolic resin.

[0073] Comparative Example 9

[0074] The difference from Example 1 is that in the preparation of the ceramic binder, the modified resin is replaced by a premix of thermosetting liquid phenolic resin and diisopropyl linoleate (i.e., no tert-butyl hydrogen peroxide aqueous solution is added for the reaction).

[0075] Comparative Example 10

[0076] The difference from Example 1 is that in the preparation of the ceramic binder, the mass ratio of ceramicized aluminum phosphate solution, silane coupling agent KH-560 and modified resin is modified to 110:48:30.

[0077] Steel molds were used, with dimensions prepared according to the standards for each testing item. The hot tamping process and heat treatment regime were strictly followed in each embodiment and comparative example to ensure process comparability. A pneumatic tamping hammer was used, with each layer tamped at a constant pressure of 0.5 MPa until the surface was smooth and dense. After curing, the bulk density at room temperature was first tested, and only those with a density of 2.85 ± 0.02 g / cm³ were selected. 3 All subsequent performance tests were conducted on samples within the specified range to eliminate interference from differences in molding density.

[0078] I. Bulk density and apparent porosity:

[0079] Sample specifications: 40mm×40mm×40mm cube, 3 parallel samples per group.

[0080] Test Procedure: Dry the sample at 110℃ to constant weight, cool it to room temperature in a desiccator, and weigh the dried mass m1. Place the sample in a container, evacuate to a pressure less than 2.5 kPa, and maintain for 30 minutes. Slowly pour in distilled water until the sample is completely submerged, continue evacuating for 30 minutes, and then let it stand at atmospheric pressure for 4 hours. Weigh the suspended mass m2 of the saturated sample in distilled water. Remove the saturated sample, quickly wipe away excess water droplets on the surface with a damp towel, ensuring that water is not absorbed from the opening, and immediately weigh its saturated apparent mass m3. Bulk density BD (g / cm³) 3 Apparent porosity AP (%) = m1 × ρwater / (m3 - m2); ρwater is taken as 1.00 g / cm³. 3.

[0081] II. High-Temperature Compressive Strength:

[0082] Sample specifications: 40mm×40mm×40mm cube, 3 parallel samples per group.

[0083] Testing Procedure: Place the specimen in the center of the indenter of the high-temperature compressive strength testing furnace. Proceed to a programmed temperature of 1400℃ from room temperature at a rate of 10℃ / min. After reaching 1400℃, hold for 30 minutes to ensure uniform temperature throughout the specimen. Under these conditions, apply a load to the specimen through the indenter at a constant loading rate of 0.5MPa / s until the specimen fails. Record the maximum load F (kN) at failure. High-temperature compressive strength (MPa) = F × 1000 / S; where S is the area of ​​the specimen subjected to pressure (40mm × 40mm = 1600mm²). 2 ).

[0084] III. High-Temperature Flexural Strength:

[0085] Sample specifications: 40mm×40mm×160mm cuboid, 3 parallel samples per group.

[0086] Testing Procedure: Place the three-point bending fixture (lower blade span L = 100 mm) into the high-temperature furnace. Place the specimen at the center of the lower blade of the fixture. Increase the temperature to 1400℃ at a rate of 10℃ / min. After reaching 1400℃, hold for 30 minutes. Apply a stress increase rate of 0.15 MPa / s until the specimen fractures. Record the maximum load F (N) at fracture. High-temperature flexural strength (MPa) = (3 × F × L) / (2 × b × h) 2 In the formula, L=100mm, b=40mm, h=40mm.

[0087] IV. Thermal shock resistance:

[0088] Sample specifications: 40mm×40mm×160mm cuboid, 9 parallel samples per group, divided into 3 initial group, 3 thermal shock group, and 3 critical group.

[0089] Testing Procedure: Place the samples from the thermal shock group and critical group into the uniform temperature zone of the furnace preheated to 1100℃ and hold for 30 minutes. Quickly remove the samples and immerse them completely in a 25℃ flowing water bath within 5 seconds for rapid cooling for 3 minutes. Remove the samples, wipe the surface dry with a towel, and dry them in a 110℃ oven for 2 hours. This process is recorded as one thermal shock cycle. Repeat the above cycle. Record the surface condition of the thermal shock group after 20 cycles. Test the room temperature flexural strength of the initial group and the room temperature flexural strength of the thermal shock group after 20 thermal shocks, and calculate the residual flexural strength rate. Residual flexural strength rate = (Pn / P0) × 100%; where Pn is the average room temperature flexural strength after the 20th cycle, and P0 is the average room temperature flexural strength of the initial group. Continue thermal shock cycling for the critical group and record the number of cycles in which a through-crack appears in the sample.

[0090] V. Abrasion resistance at room temperature:

[0091] Sample specifications: φ114mm×25mm round disc, 3 parallel samples per group, dried at 110℃ to constant weight.

[0092] Test parameters: Abrasive: F80 (median particle size approximately 0.18 mm) brown corundum abrasive. Abrasive flow rate: 200 g / min. Blasting pressure: 0.1 MPa. Blasting time: 10 minutes. Blasting distance: 100 mm. Blasting angle: 90°. Sample mass before test: m0; Sample mass after test: m1. Volumetric wear (cm²) 3 ) = (m0 - m1) / BD; where BD is the bulk density of the sample in this project (g / cm³). 3 ).

[0093] VI. Rate of change of permanent linear velocity during heating:

[0094] Sample specifications: 25mm×25mm×100mm cuboid, with parallel end faces, 3 parallel samples per group.

[0095] Test Procedure: Measure the initial length L0 at room temperature at the center of both ends of the sample along its length. Take the average of the three measurements. Place the sample vertically in the homogenization zone of a high-temperature furnace and heat it to 1500℃ at a rate of 5℃ / min, holding for 3 hours. Allow it to cool naturally to room temperature with the furnace. Measure the sample length L1 again at the same location. Permanent linear change rate (%) = [(L1-L0) / L0] × 100%.

[0096] VII. Resistance to Alkali Corrosion:

[0097] Sample specifications: Prepare a lidded crucible with an inner diameter of 40 mm and a depth of 40 mm, with 3 parallel samples per group, and dry at 110℃.

[0098] Erosion medium: Chemically pure K2CO3 and Na2CO3 are mixed in a 1:1 mass ratio and filled to the crucible volume (approximately 20 cm³).3 ).

[0099] Testing Procedure: Fill the crucible with the mixed alkali powder, gently tap to compact, and cover with the crucible lid. Place the crucible in a high-temperature furnace, heat to 1450℃ at a rate of 5℃ / min, and hold for 5 hours. Cool to room temperature with the furnace, and carefully cut open the crucible. Erosion Penetration Thickness (mm): Use vernier calipers to measure the maximum depth of the erosion front (where there is a significant change in color and structure) from the original working surface on the cross-section, and take the average value of multiple measurement points.

[0100] Table 1. Test Results (Average Values)

[0101]

[0102] Examples 1 to 3 use magnesium ceramic aggregate as a strong and tough skeleton, with core phase magnesium oxide providing strength, shell phase spinel and zirconium oxide reducing thermal expansion, self-healing ceramic powder achieving damage closure, releasing the core to fill cracks at high temperatures, composite ceramic binder ensuring strong adhesion across the entire temperature range, low temperature toughening by resin, high temperature ceramicization by aluminum phosphate, and other components such as hexagonal boron nitride toughening and cerium oxide catalytic strengthening. The functions of each raw material are complementary, dispersing thermal stress, inhibiting crack propagation, and balancing thermal shock resistance with wear and corrosion resistance.

[0103] In Comparative Example 1, the magnesia-ceramic aggregate was replaced with pure reburned magnesia. The core-shell structure of the magnesia-ceramic aggregate is the core of its performance. The core phase of reburned magnesia provides basic strength, while the shell phases of magnesium aluminum spinel and yttrium-stabilized zirconium oxide reduce thermal expansion and cracking. The carbon film formed by the carbonization of spinning pitch enhances interfacial bonding. Pure reburned magnesia does not have the above-mentioned modification effects. The particles are simply stacked together, resulting in uneven pore distribution. During thermal shock, thermal stress cannot be effectively dispersed, leading to insufficient structural stability, thermal shock resistance, and corrosion resistance.

[0104] In Comparative Example 2, the magnesium-ceramic aggregate lacked sintering at 1500℃: High-temperature sintering is crucial for forming a stable composite crystalline phase, promoting solid solution reactions between components, reducing lattice defects, and increasing aggregate density. Without this step, the internal crystalline phase of the aggregate is incompletely developed, resulting in numerous micropores and interfacial cracks. As a skeleton, it cannot effectively disperse stress, making it prone to structural deterioration at high temperatures, which in turn leads to a comprehensive decline in strength, thermal shock resistance, wear resistance, and volumetric stability.

[0105] Furthermore, the core aggregate of Comparative Example 1 is pure reburned magnesia. Although it lacks the core-shell modified structure of magnesia-ceramic aggregate, the reburned magnesia itself has a relatively complete crystal phase development and a dense structure. The skeleton formed by the gradation stacking between particles has basic strength and density, without any additional process defects. In contrast, the aggregate of Comparative Example 2 is magnesia-ceramic aggregate that has not undergone final sintering. This aggregate lacks a high-temperature sintering step, resulting in insufficient solid solution reaction and composite crystal phase formation inside, leaving a large number of micropores, interface cracks, and incompletely carbonized spinning pitch residue. At the same time, the bonding between magnesia-alumina spinel, yttrium-stabilized zirconium oxide, and the magnesia core is only a physical coating, without forming a strong ceramic grain boundary bond. The aggregate itself is a defective skeleton. Therefore, the performance of the ramming mix of Comparative Example 2 is worse than that of the ramming mix of Comparative Example 1.

[0106] In Comparative Example 3, the amount of self-healing ceramic powder was reduced, while the amount of lightly calcined magnesia powder was increased. The microcapsule structure of the self-healing ceramic powder is the core of microcrack repair. Upon heating, the aluminum-magnesium alloy released from the core forms a repair-combination crack, that is, it reacts with magnesia to form a magnesium-aluminum solid solution-ceramic composite phase, thereby achieving crack repair and inhibiting propagation. After the amount of self-healing ceramic powder was reduced, there were insufficient active sites for microcrack repair, and the damage tolerance decreased. Although lightly calcined magnesia powder can improve the density to a certain extent, it has no repair function and cannot make up for the shortcomings. Moreover, excessive magnesia is prone to affecting the volume stability due to crystal phase transformation. At the same time, the reinforcing effect of the ceramic phase is weakened, and the wear resistance and corrosion resistance decrease.

[0107] In Comparative Example 4, the self-healing ceramic powder was replaced with pure aluminum-magnesium alloy powder. The self-healing ceramic powder has a cordierite-mullite composite phase in its capsule wall, which can effectively control the core release rate and prevent premature oxidation failure. At the same time, the capsule wall itself enhances high-temperature stability. Pure aluminum-magnesium alloy powder lacks capsule wall protection, and undergoes extensive oxidation during preparation and the initial high-temperature stage, losing its repair potential. Furthermore, the volume changes generated during oxidation can easily cause initial internal damage. The lack of ceramic phase reinforcement results in insufficient interparticle bonding, leading to deterioration in thermal shock resistance, structural stability, and corrosion resistance.

[0108] In Comparative Example 5, the self-healing ceramic powder lacked ammonia curing agent: The core function of the ammonia curing agent is to promote the cross-linking and polymerization of the wall material, forming a complete and dense microcapsule wall. When missing, the wall material cannot fully cure, resulting in pores, cracks, or even ruptures in the capsule wall. This leads to premature leakage and oxidation of the aluminum-magnesium alloy powder in the capsule core, significantly reducing repair efficiency. The incomplete capsule wall cannot provide reinforcement, increasing the internal porosity of the material, affecting high-temperature strength and corrosion resistance, and decreasing volume stability due to structural defects.

[0109] Furthermore, while Comparative Example 4 lacks the on-demand release function of self-healing ceramic powder, the aluminum-magnesium alloy powder itself is a highly active component. During material preparation and the initial high-temperature phase, it undergoes direct oxidation, and the resulting oxidation products, such as magnesium-aluminum oxides, can fill some of the initial pores, providing a certain passive reinforcement effect on the material structure without introducing additional structural defects. In Comparative Example 5, the cordierite, mullite, and tetraethyl orthosilicate system cannot fully cross-link and polymerize, resulting in numerous pores and cracks in the capsule wall, and even some microcapsules rupturing directly. This leads to two key problems: first, the aluminum-magnesium alloy powder in the capsule core leaks and oxidizes prematurely, completely losing its core function of repairing cracks during thermal shock; second, the defective capsule wall itself becomes a weak point within the material, and these incomplete ceramic wall materials cannot play a reinforcing role, instead forming dispersed pores and interfacial cracks, disrupting the continuity of the material structure. Therefore, the performance of the ramming mix in Comparative Example 5 is worse than that in Comparative Example 4.

[0110] In Comparative Example 6, the ceramic binder was replaced with pure ceramicized aluminum phosphate solution: the ceramic binder was a composite system of ceramicized aluminum phosphate solution, modified resin, and silane coupling agent. The modified resin improved the low-temperature bonding strength and moldability, and at high temperatures, it synergistically formed a dense ceramic bonding phase with aluminum phosphate. Pure ceramicized aluminum phosphate solution had poor low-temperature bonding performance, uneven particle dispersion during molding, and insufficient density of the bonding phase at high temperatures, leading to weakened interfacial bonding force, decreased structural stability, and consequently, deterioration in strength, thermal shock resistance, and wear and corrosion resistance.

[0111] In Comparative Example 7, the ceramic binder lacked the silane coupling agent KH-560: Silane coupling agent KH-560 acts as an interfacial bridge, improving the compatibility between the inorganic phase (aluminum phosphate, aggregates, etc.) and the organic phase (modified resins, etc.) through chemical bonding, promoting uniform mixing. Without it, the two phases only undergo physical adsorption or mechanical interlocking, resulting in weak and unevenly distributed interfacial bonding, becoming a weak area for stress concentration and crack initiation. Under thermal shock or mechanical loads, cracks easily propagate along the interface, leading to a decrease in overall strength, toughness, and thermal shock resistance. Simultaneously, the interfacial defect provides a penetration channel for corrosive media, weakening corrosion resistance.

[0112] In Comparative Example 8, the modified resin was replaced with pure thermosetting liquid phenolic resin: the modified resin was toughened with diisopropyl linoleate and crosslinked with tert-butyl hydroperoxide, possessing both flexibility and high-temperature stability. The carbon film formed by carbonization at high temperatures can reinforce the ceramic bonding phase. Pure thermosetting liquid phenolic resin is brittle, prone to cracking at low temperatures, and decomposes rapidly at high temperatures, producing a large amount of gas, leading to a sharp increase in internal porosity and a significant decrease in bonding strength; it cannot buffer thermal stress, and cracks propagate rapidly during thermal shock. At the same time, increased porosity and insufficient bonding strength exacerbate the deterioration of wear and corrosion resistance.

[0113] Furthermore, Comparative Example 6, using pure ceramicized aluminum phosphate liquid, although lacking the gradient reinforcement effect of composite binders, can stably transform into a ceramic bonding phase at high temperatures, forming a relatively dense inorganic bonding network with basic high-temperature structural stability. Its bonding method is mainly inorganic chemical bonding, without significant high-temperature decomposition failure issues. In contrast, Comparative Example 8, using pure phenolic resin without diisopropyl linoleate toughening and tert-butyl hydroperoxide crosslinking modification, exhibits extremely high crosslinking density after curing, resulting in significant brittleness. Moreover, under high-temperature conditions, the pure phenolic resin decomposes rapidly, generating a large amount of gas, leading to the formation of additional pores and microcracks within the material. Therefore, the performance of the ramming mix in Comparative Example 8 is worse than that in Comparative Example 6.

[0114] In Comparative Example 9, the modified resin lacked tert-butyl hydroperoxide: tert-butyl hydroperoxide, acting as an initiator, promotes the cross-linking reaction between phenolic resin and diisopropyl linoleate, enhancing resin stability. Without it, the cross-linking reaction is incomplete, resulting in a loose resin structure, weak low-temperature bonding, and easy decomposition at high temperatures to generate gas, leading to increased material porosity and reduced bonding strength. The loose structure cannot buffer thermal stress, resulting in significant stress concentration during thermal shock and decreased thermal shock resistance. Furthermore, the defects remaining after resin decomposition further weaken wear resistance, corrosion resistance, and volume stability.

[0115] Furthermore, although Comparative Example 8 was not toughened and exhibited significant brittleness, the phenolic resin could react to form a basic rigid framework, providing fundamental low- and medium-temperature bonding strength. It only exhibited brittle cracking and decomposition failure at high temperatures. In contrast, the insufficiently cross-linked resin system of Comparative Example 9 was merely a physical blend of phenolic resin and diisopropyl linoleate, failing to form a stable chemical bonding network. This loose resin structure presented two major problems: firstly, its low- and medium-temperature bonding strength was far weaker than that of fully cross-linked pure phenolic resin, resulting in weak interparticle bonding; secondly, at high temperatures, the uncross-linked flexible components easily migrated and precipitated, and the resin decomposed rapidly, generating more gas, leading to the formation of pores and interfacial cracks within the material. The failure of the binder system was more thorough than that of pure phenolic resin, resulting in the ramming mix of Comparative Example 9 exhibiting significantly worse performance than that of Comparative Example 8.

[0116] In Comparative Example 10, the proportions of the ceramic binder components were unbalanced: the original proportions of the ceramic binder, after optimization, achieved a synergistic balance between interfacial compatibility, bonding strength, and thermal shock buffering. After the proportions were adjusted, insufficient modified resin weakened the low-temperature bonding and high-temperature carbon film reinforcement effects, while excessive silane coupling agent easily agglomerated, forming interfacial defects. The synergistic effect of the three components was destroyed, the uniformity of the internal structure of the material decreased, and consequently, the overall strength, thermal shock resistance, and corrosion resistance deteriorated.

Claims

1. A thermal shock resistant furnace lining refractory material, characterized in that, The raw materials include the following parts by weight: 45 to 50 parts magnesium ceramic aggregate, 12 to 18 parts self-healing ceramic powder, 10 to 15 parts lightly calcined magnesium oxide powder, 8 to 14 parts ceramic binder, 3 to 8 parts hexagonal boron nitride, 2 to 5 parts mullite powder, and 1 to 2 parts cerium oxide. The magnesium ceramic aggregate is obtained by bonding and coating recalcined magnesium oxide with magnesium aluminum spinel and yttrium stabilized zirconium oxide through spinning pitch, and sintering at 600℃~650℃ and 1450℃~1550℃; the mass ratio of recalcined magnesium oxide, spinning pitch, magnesium aluminum spinel and yttrium stabilized zirconium oxide is 100:(3~5):(4~6):(1~2); The self-healing ceramic powder is obtained by reacting aluminum-magnesium alloy powder, wall material, and ammonia curing agent in a mass ratio of (50-55):(200-220):(15-20); the wall material is prepared by mixing cordierite powder, mullite powder, tetraethyl orthosilicate, and anhydrous ethanol in a mass ratio of (23-27):(19-25):(50-60):(150-200) and adjusting the pH to 2.8-3.

2. The ceramic binder is prepared by mixing ceramicized aluminum phosphate solution, silane coupling agent KH-560 and modified resin in a mass ratio of (100-120):(5-7):(60-80); the ceramicized aluminum phosphate solution is prepared by mixing phosphoric acid aqueous solution, aluminum hydroxide and nano cordierite in a mass ratio of (100-120):(40-45):(5-8); the modified resin is prepared by reacting thermosetting liquid phenolic resin, diisopropyl linoleate and tert-butyl hydrogen peroxide aqueous solution in a mass ratio of 100:(8-12):(1.5-2.5).

2. The thermal shock resistant furnace lining refractory material according to claim 1, characterized in that, The preparation method of the magnesium ceramic aggregate includes the following steps: according to the mass ratio of reburned magnesium oxide: spinning pitch: magnesium aluminum spinel: yttrium stabilized zirconium oxide = 100: (3~5): (4~6): (1~2), first mix magnesium aluminum spinel and yttrium stabilized zirconium oxide evenly, add spinning pitch and mix evenly to obtain the modified material; The modified material was added to the reburned magnesium oxide and mixed and coated at 350℃~400℃ and 60rpm~80rpm for 1.5h~2h. It was then sintered at 600℃~650℃ for 30min~50min and sintered at 1450℃~1550℃ for 1h~1.5h. After cooling to room temperature, it was dispersed and sieved to obtain magnesium ceramic aggregate with a particle size range of 0.2mm~6mm.

3. The thermal shock resistant furnace lining refractory material according to claim 2, characterized in that, The gradation of the reburned magnesium oxide is as follows: 55wt% to 60wt% of particles with a particle size of 2mm < ≤ 6mm, and 40wt% to 45wt% of particles with a particle size of 0.2mm < ≤ 2mm; the median particle size of the spinning pitch is below 3μm; the median particle size of the magnesium aluminum spinel is 2μm to 8μm; and the median particle size of the yttrium stabilized zirconium oxide is below 3μm.

4. The thermal shock resistant furnace lining refractory material according to claim 1, characterized in that, The preparation method of the self-healing ceramic powder includes the following steps: Cordierite powder, mullite powder, tetraethyl orthosilicate and anhydrous ethanol are mixed in a mass ratio of (23-27):(19-25):(50-60):(150-200), and the pH is adjusted to 2.8-3.2 to obtain a wall material; aluminum-magnesium alloy powder is added to the wall material in a mass ratio of aluminum-magnesium alloy powder:wall material:ammonia curing agent = (50-55):(200-220):(15-20), stirred, and ammonia curing agent is added dropwise to form a microcapsule suspension; the mixture is filtered, the solid is collected, vacuum dried, dispersed, and sieved to obtain the self-healing ceramic powder.

5. The thermal shock resistant furnace lining refractory material according to claim 4, characterized in that, The median particle size of the cordierite powder is 1 μm to 5 μm; the median particle size of the mullite powder is 1 μm to 5 μm; the median particle size of the aluminum-magnesium alloy powder is 20 μm to 30 μm; the stirring is carried out at 65℃ to 75℃ and 350 rpm to 400 rpm for 30 min to 40 min; the ammonia curing agent is 20 wt% to 25 wt% ammonia curing agent; the reaction time is 2.5 h to 3 h.

6. The thermal shock resistant furnace lining refractory material according to claim 1, characterized in that, The preparation method of the ceramic binder includes the following steps: stirring according to the mass ratio of phosphoric acid aqueous solution: aluminum hydroxide: nano cordierite = (100-120): (40-45): (5-8) to obtain ceramicized aluminum phosphate solution; stirring thermosetting liquid phenolic resin: diisopropyl linoleate: tert-butyl hydrogen peroxide aqueous solution = 100: (8-12): (1.5-2.5) at 60℃-65℃, and adding tert-butyl hydrogen peroxide. The aqueous solution was heated to 85℃~90℃ and stirred under nitrogen protection. After cooling, the modified resin was obtained. The silane coupling agent KH-560 was added to the ceramicized aluminum phosphate solution according to the mass ratio of ceramicized aluminum phosphate solution: silane coupling agent KH-560: modified resin = (100~120): (5~7): (60~80). The mixture was stirred at 60℃~65℃ and then cooled to obtain a mixture. Under nitrogen protection and stirring, the mixture was added to the modified resin and stirred continuously. Vacuum degassing was performed to obtain the ceramic binder.

7. The thermal shock resistant furnace lining refractory material according to claim 6, characterized in that, The phosphoric acid aqueous solution is an 80wt% to 85wt% phosphoric acid aqueous solution; the tert-butyl hydrogen peroxide aqueous solution is a 65wt% to 70wt% tert-butyl hydrogen peroxide aqueous solution; the cooling is to a temperature of 45℃ to 50℃.

8. The thermal shock resistant furnace lining refractory material according to claim 1, characterized in that, The median particle size of the lightly calcined magnesium oxide powder is 20 μm to 40 μm; the hexagonal boron nitride is nanoscale; the median particle size of the mullite powder is 1 μm to 5 μm; and the cerium oxide is nanoscale.

9. The method for preparing a thermal shock resistant furnace lining refractory material according to claim 1, characterized in that, The process includes the following steps: mixing magnesium ceramic aggregate and lightly calcined magnesium oxide powder in a dry mixture; adding a pre-mixed mixture of self-healing ceramic powder, hexagonal boron nitride, mullite powder, and cerium oxide; mixing in a dry mixture; finally adding ceramic binder; mixing in a wet mixture; hot tamping to form the desired shape; and curing.

10. The method for preparing a thermal shock resistant furnace lining refractory material according to claim 9, characterized in that, The hot tamping molding is performed by heating to 130℃~160℃ and tamping; the curing is performed by heating to 200℃~300℃ and holding for 2h~3h, heating to 500℃~600℃ and holding for 1h~2h, and then naturally cooling to room temperature.

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