Refractory materials with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide and their preparation methods

Abstract

This invention relates to a refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide and its preparation method. The technical solution is as follows: using 55-65 wt% fused chromium-aluminum particles, 5-15 wt% zirconium oxide particles, 10-20 wt% chromium oxide fine powder, 8-12 wt% lightly calcined magnesia fine powder, and 2-8 wt% chromium-aluminum-carbon fine powder as raw materials, with 3-5 wt% resin added as an external raw material; first, the fused chromium-aluminum particles are placed in a mixer and stirred, while simultaneously adding 2-2.5 wt% resin at a uniform speed, and stirring; then, lightly calcined magnesia fine powder is added, and stirring continues; then, zirconium oxide particles, chromium oxide fine powder, chromium-aluminum-carbon fine powder, and the remaining resin are added, and stirring continues. The mixture is then bound, machine-pressed, dried, heated to 1600-1780℃ in a carbon-buried atmosphere, held at that temperature, and cooled to obtain the Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide refractory material. The products of this invention have excellent resistance to coal slag erosion, good thermal shock stability, excellent high-temperature strength, and long high-temperature service life.

Description

Technical Field

[0001] This invention belongs to the technical field of chromium oxide refractory materials. Specifically, it relates to a refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide and its preparation method. Background Technology

[0002] Existing high-chromium bricks mainly use fused chromium-aluminum as aggregate, chromium oxide fine powder as matrix and phosphate as binder. After mixing, they are machine-pressed and fired in a high-temperature kiln at 1900℃ for an extended period of 10-16 hours to obtain dense high-chromium brick products with high bonding strength. However, their service life is greatly affected when they are used at high temperatures. For example, Gao Zhenxin et al. (Gao Zhenxin, Wang Zhanmin, Fan Muxu, et al. Study on the microstructure of chromium oxide bricks for coal-water slurry gasifiers [J]. Refractory Materials, 2017, 51(6):401-407.) studied the microstructure of high-chromium bricks. Their microstructure showed that the high-chromium bricks were based on Cr2O3-Al2O3 solid solution as the bonding phase. During high-temperature service, the desolvation-solution process of the solid solution led to a decrease in the overall material structure stability. This process also limited the improvement of the thermal shock resistance of high-chromium bricks, causing a significant decrease in their service life under frequent thermal shock cycles. In extreme cases, thermal shock-induced structural spalling may occur, which may even directly lead to gasifier shutdown or safety accidents.

[0003] Other researchers (J. Chen et al., Corrosion mechanism of Cr2O3-Al2O3-ZrO2refractories in a coal-water slurry gasifier: A post-mortem analysis, Corrosion Science, 2020, 163:108250.) have found that Cr(III) is converted into Cr(VI) during the gasification process of coal from different sources, leading to environmental pollution problems.

[0004] In addition, the patented technology "A method for producing high-chromium bricks containing nanocomposite particles" (CN201010295751.2) introduces nanoparticles such as Al2O3, Cr2O3, and ZrO2 into high-chromium bricks through a combination of chemical and mechanical dispersion. This utilizes the nanocomposite effect to improve the material's thermal shock resistance to a certain extent. However, besides poor dispersibility and high cost, the most significant issue with nano-oxide powders is that they undergo grain growth under the high-temperature service conditions of high-chromium bricks. This sintering volume effect generated during service can lead to structural failure and severely reduce the material's thermal shock resistance.

[0005] For example, the patented technology of "a chromium oxide refractory material and its preparation method" (CN201810969306.6) uses fused chromium oxide particles as aggregate, fused chromium oxide fine powder and fused silica powder as matrix, and obtains chromium oxide refractory material through ball milling, stirring and mixing and pressing. During service, the chromium oxide refractory material prepared by this technology is also very easy to be eroded and peeled off by coal slag, which causes Cr(III) to transform into Cr(VI). This not only affects the service performance, but the generated Cr(VI) is also extremely harmful to the environment and human health. Summary of the Invention

[0006] The present invention aims to overcome the shortcomings of the prior art and provides a simple and energy-efficient method for preparing Cr2AlC / Mg(Al,Cr)2O4 refractory materials directly bonded with chromium oxide. The Cr2AlC / Mg(Al,Cr)2O4 refractory materials directly bonded with chromium oxide prepared by this method have excellent resistance to coal slag erosion, good thermal shock stability, excellent high-temperature strength, and long high-temperature service life. They can also improve environmental protection and meet the needs of gasifiers for different coal types.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] Step 1: Prepare the raw materials using 55-65 wt% fused chromium-aluminum particles, 5-15 wt% zirconium oxide particles, 10-20 wt% chromium oxide fine powder, 8-12 wt% light-burned magnesia fine powder, and 2-8 wt% chromium-aluminum-carbon fine powder, plus 3-5 wt% resin. First, place the fused chromium-aluminum particles in a mixer and stir, while simultaneously adding 2-2.5 wt% resin at a uniform rate, continuing stirring for 5-10 minutes. Then, add the light-burned magnesia fine powder and continue stirring for 10-15 minutes. Finally, add the zirconium oxide particles, the chromium oxide fine powder, the chromium-aluminum-carbon fine powder, and the remaining resin, continuing stirring for 5-10 minutes to obtain a mixture.

[0009] Step 2: The mixture is conditioned for 12-14 hours, machine-pressed at 200-300 MPa, and dried at 200-220℃ for 20-24 hours to obtain a dried green body; the dried green body is heated to 1600-1780℃ in a carbon-buried atmosphere at a rate of 3-5℃ / min, held for 3-6 hours, and cooled in the furnace to obtain a refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide.

[0010] The Cr2O3 content in the fused chromium-aluminum particles is ≥98wt%, and the Al2O3 content is ≤0.3wt%. The particle size of the fused chromium-aluminum particles is 0.088mm~1.0mm.

[0011] The zirconium oxide particles contain ≥95wt% ZrO2; the particle size of the zirconium oxide particles is 0.088mm to 1mm.

[0012] The Cr2O3 content in the chromium oxide fine powder is ≥99.5wt%; the particle size of the chromium oxide fine powder is ≤74μm.

[0013] The MgO content in the lightly calcined magnesium oxide fine powder is ≥99.6wt%; the particle size of the lightly calcined magnesium oxide fine powder is ≤88μm.

[0014] The Cr2AlC content in the chromium aluminum carbon fine powder is ≥99.6wt%; the particle size of the chromium aluminum carbon fine powder is ≤45μm.

[0015] The resin has a carbon residue rate of ≥35%; the resin is in liquid state.

[0016] By adopting the above technical solution, the present invention has the following advantages compared with the prior art:

[0017] 1. This invention employs a mixing and milling process involving fused chromium-aluminum particles, a resin binder, and lightly calcined magnesium oxide powder. The resin binder coats the lightly calcined magnesium oxide powder onto the surface of the fused chromium-aluminum particles, enabling the preferential in-situ formation of a Cr2O3-Mg(Al,Cr)2O4 (spinel) core-shell structure during subsequent high-temperature firing. Simultaneously, the introduction of lightly calcined magnesium oxide powder into the matrix transforms the Cr2O3-Al2O3 solid solution phase in the original aggregate matrix into a Mg(Al,Cr)2O4 composite spinel phase, resulting in a spinel phase with high refractoriness and excellent thermal shock resistance (spinel thermal expansion coefficient: 8.9 × 10⁻⁶). -6 / K) is introduced into Cr2O3-Al2O3 refractory materials (chromium oxide thermal expansion coefficient: 9.0×10). -6 / K), transforming the original Cr2O3-Al2O3 solid solution bonded system between aggregate and matrix into a Cr2O3-Mg(Al,Cr)2O4 (spinel) core-shell structure aggregate-matrix bond, on the one hand, forms a high-temperature stable composite spinel bond phase between the aggregate surface and the matrix, improving the bond strength and thermal shock resistance; on the other hand, through the Mg(Al,Cr)2O4 composite spinel bond, the influence of temperature fluctuations during high-temperature service on the solid solution-desolution process of the original Cr2O3-Al2O3 solid solution on the overall high-temperature stability of the material is avoided, effectively improving the high-temperature stability of refractory materials with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide.

[0018] 2. This invention introduces the highly thermally conductive and thermally shock resistant Cr2AlC phase into the Cr2O3-Al2O3 refractory matrix. Without introducing new elements, it controls the phase composition, microstructure evolution, and expansion effect of the Cr2AlC phase during heat treatment to prepare a high-density Cr2AlC directly bonded system, thus optimizing the matrix design of the product. Simultaneously, it controls the morphology and type of the Cr2AlC secondary phase to achieve a toughening and strengthening effect on the material. Furthermore, the elemental composition of the newly introduced Cr2AlC phase is essentially consistent with the Cr2O3-Al2O3 refractory system, avoiding structural instability under high-temperature conditions caused by complex refractory phase composition. This effectively ensures the high-temperature structural stability of the refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide during slag erosion.

[0019] 3. This invention constructs a novel Cr2O3-Mg(Al,Cr)2O4 core-shell aggregate-matrix bonding morphology on the surface of Cr2O3 aggregate. Through the inducing effect of Mg(Al,Cr)2O4 composite spinel on the erosion and penetration behavior of the coal slag erosion medium (Fe, Mn ions), the penetration of coal slag is greatly reduced, improving the product's resistance to coal slag erosion. Simultaneously, it significantly reduces the valence transformation probability of Cr(III), improving environmental protection. Therefore, through the optimization of the Cr2O3-Mg(Al,Cr)2O4 core-shell aggregate-matrix interface and the construction of the matrix system, a high-strength, tough, and thermally shock resistant / coal slag resistant refractory material with direct chromium oxide bonding to Cr2AlC / Mg(Al,Cr)2O4 is ultimately obtained.

[0020] The refractory material prepared by this invention, consisting of Cr2AlC / Mg(Al,Cr)2O4 directly bonded with chromium oxide, was tested and found to have the following characteristics: apparent porosity of 5.21–9.80% and bulk density of 4.35–4.43 g / cm³. 3 The flexural strength at 1400℃ is 36.8–48.3 MPa; the strength retention rate after three water cooling cycles from 1100℃ to 20℃ is 52%–68%; under the erosion resistance test at 1600℃ for 10 hours, the erosion depth against slag 1 is 1.20–1.66 mm, and the erosion depth against slag 2 is 1.54–1.98 mm, with no melting loss in either case.

[0021] Therefore, the present invention has the characteristics of simple process and low production energy consumption. The refractory material of Cr2AlC / Mg(Al,Cr)2O4 directly combined with chromium oxide has the characteristics of excellent resistance to coal slag erosion, good thermal shock stability, excellent high temperature strength and long high temperature service life. Attached Figure Description

[0022] Figure 1This invention describes the microstructure of a refractory matrix consisting of Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide, prepared according to the present invention.

[0023] Figure 2 yes Figure 1 The image shows the microstructure of the refractory aggregate surface where Cr2AlC / Mg(Al,Cr)2O4 is directly bonded to chromium oxide. Detailed Implementation

[0024] To further understand the present invention, the following description, in conjunction with the accompanying drawings and specific embodiments, is intended to limit the scope of the claims of the present invention.

[0025] A refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide and its preparation method. The specific embodiment of the preparation method is described below.

[0026] Step 1: Prepare the raw materials using 55-65 wt% fused chromium-aluminum particles, 5-15 wt% zirconium oxide particles, 10-20 wt% chromium oxide fine powder, 8-12 wt% light-burned magnesia fine powder, and 2-8 wt% chromium-aluminum-carbon fine powder, plus 3-5 wt% resin. First, place the fused chromium-aluminum particles in a mixer and stir, while simultaneously adding 2-2.5 wt% resin at a uniform rate, continuing stirring for 5-10 minutes. Then, add the light-burned magnesia fine powder and continue stirring for 10-15 minutes. Finally, add the zirconium oxide particles, the chromium oxide fine powder, the chromium-aluminum-carbon fine powder, and the remaining resin, continuing stirring for 5-10 minutes to obtain a mixture.

[0027] Step 2: The mixture is conditioned for 12-14 hours, machine-pressed at 200-300 MPa, and dried at 200-220℃ for 20-24 hours to obtain a dried green body; the dried green body is heated to 1600-1780℃ in a carbon-buried atmosphere at a rate of 3-5℃ / min, held for 3-6 hours, and cooled in the furnace to obtain a refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide.

[0028] In this specific implementation method;

[0029] The Cr2O3 content in the fused chromium-aluminum particles is ≥98wt%, and the Al2O3 content is ≤0.3wt%. The particle size of the fused chromium-aluminum particles is 0.088~1.0mm.

[0030] The zirconium oxide particles contain ≥95wt% ZrO2; the particle size of the zirconium oxide particles is 0.088~1mm.

[0031] The Cr2O3 content in the chromium oxide fine powder is ≥99.5wt%; the particle size of the chromium oxide fine powder is ≤74μm.

[0032] The MgO content in the lightly calcined magnesium oxide fine powder is ≥99.6wt%; the particle size of the lightly calcined magnesium oxide fine powder is ≤88μm.

[0033] The Cr2AlC content in the chromium aluminum carbon fine powder is ≥99.6wt%; the particle size of the chromium aluminum carbon fine powder is ≤45μm.

[0034] The resin has a carbon residue rate of ≥35%; the resin is in liquid state.

[0035] The details will not be repeated in the examples.

[0036] Example 1

[0037] A refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide and its preparation method. The preparation method of this embodiment is described below.

[0038] Step 1: Prepare the raw materials using 55 wt% fused chromium-aluminum particles, 15 wt% zirconium oxide particles, 10 wt% chromium oxide fine powder, 12 wt% light-burned magnesium oxide fine powder, and 8 wt% chromium-aluminum-carbon fine powder, plus 3 wt% resin. First, place the fused chromium-aluminum particles in a mixer and stir, while simultaneously adding 2 wt% resin at a uniform speed, and continue stirring for 5 minutes; then add the light-burned magnesium oxide fine powder and continue stirring for 15 minutes; finally, add the zirconium oxide particles, the chromium oxide fine powder, the chromium-aluminum-carbon fine powder, and the remaining resin, and continue stirring for 8 minutes to obtain a mixture.

[0039] Step 2: The mixture is conditioned for 12 hours, machine-pressed at 200 MPa, and dried at 220°C for 20 hours to obtain a dried green body; the dried green body is heated to 1600°C at a rate of 3°C / min in a carbon-buried atmosphere, held for 6 hours, and cooled in the furnace to obtain a refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide.

[0040] At least two Φ36mm×36mm samples were drilled from the Cr2AlC / Mg(Al,Cr)2O4 refractory material directly bonded with chromium oxide, and buried in different coal slags as shown in Table 1. The chemical composition of coal slag 1 and coal slag 2 is detailed in Table 1. The melting area and penetration depth of the samples were tested at 1600℃ for 10 hours.

[0041] Table 1. Chemical composition (wt%) of different coal slags

[0042]

[0043] The test results of the Cr2AlC / Mg(Al,Cr)2O4 refractory material directly bonded with chromium oxide prepared in this embodiment are shown in Table 2.

[0044] Table 2. Test results of the products manufactured in this embodiment.

[0045]

[0046] Example 2

[0047] A refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide and its preparation method. The preparation method of this embodiment is described below.

[0048] Step 1: Prepare the raw materials using 65 wt% fused chromium-aluminum particles, 5 wt% zirconium oxide particles, 20 wt% chromium oxide fine powder, 8 wt% light-burned magnesium oxide fine powder, and 2 wt% chromium-aluminum-carbon fine powder, plus 5 wt% resin. First, place the fused chromium-aluminum particles in a mixer and stir, while simultaneously adding 2.5 wt% resin at a uniform speed, and continue stirring for 9 minutes; then add the light-burned magnesium oxide fine powder and continue stirring for 13 minutes; finally, add the zirconium oxide particles, the chromium oxide fine powder, the chromium-aluminum-carbon fine powder, and the remaining resin, and continue stirring for 10 minutes to obtain a mixture.

[0049] Step 2: The mixture is conditioned for 14 hours, machine-pressed at 300 MPa, and dried at 200°C for 24 hours to obtain a dried green body; the dried green body is heated to 1780°C at a rate of 5°C / min in a carbon-buried atmosphere, held for 3 hours, and cooled in the furnace to obtain a refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide.

[0050] At least two Φ36mm×36mm samples were drilled from the Cr2AlC / Mg(Al,Cr)2O4 refractory material directly bonded with chromium oxide, and buried in different coal slags as shown in Table 1. The chemical composition of coal slag 1 and coal slag 2 is detailed in Table 1. The melting area and penetration depth of the samples were tested at 1600℃ for 10 hours.

[0051] Table 1. Chemical composition (wt%) of different coal slags

[0052]

[0053] The test results of the Cr2AlC / Mg(Al,Cr)2O4 refractory material directly bonded with chromium oxide prepared in this embodiment are shown in Table 2.

[0054] Table 2. Test results of the products manufactured in this embodiment.

[0055]

[0056] Example 3

[0057] A refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide and its preparation method. The preparation method of this embodiment is described below.

[0058] Step 1: Prepare the raw materials using 58 wt% fused chromium-aluminum particles, 12 wt% zirconium oxide particles, 14 wt% chromium oxide fine powder, 9 wt% light-burned magnesium oxide fine powder, and 7 wt% chromium-aluminum-carbon fine powder, plus 4 wt% resin. First, place the fused chromium-aluminum particles in a mixer and stir, while simultaneously adding 2.2 wt% resin at a uniform speed, continuing stirring for 8 minutes. Then, add the light-burned magnesium oxide fine powder and continue stirring for 11 minutes. Finally, add the zirconium oxide particles, the chromium oxide fine powder, the chromium-aluminum-carbon fine powder, and the remaining resin, and continue stirring for 5 minutes to obtain a mixture.

[0059] Step 2: The mixture is conditioned for 13 hours, machine-pressed at 260 MPa, and dried at 220°C for 22 hours to obtain a dried green body; the dried green body is heated to 1750°C at a rate of 4°C / min in a carbon-buried atmosphere, held for 4 hours, and cooled in the furnace to obtain a refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide.

[0060] At least two Φ36mm×36mm samples were drilled from the Cr2AlC / Mg(Al,Cr)2O4 refractory material directly bonded with chromium oxide, and buried in different coal slags as shown in Table 1. The chemical composition of coal slag 1 and coal slag 2 is detailed in Table 1. The melting area and penetration depth of the samples were tested at 1600℃ for 10 hours.

[0061] Table 1. Chemical composition (wt%) of different coal slags

[0062]

[0063] The test results of the Cr2AlC / Mg(Al,Cr)2O4 refractory material directly bonded with chromium oxide prepared in this embodiment are shown in Table 2.

[0064] Table 2. Test results of the products manufactured in this embodiment.

[0065]

[0066] Example 4

[0067] A refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide and its preparation method. The preparation method of this embodiment is described below.

[0068] Step 1: Prepare the raw materials using 63 wt% fused chromium-aluminum particles, 7 wt% zirconium oxide particles, 16 wt% chromium oxide fine powder, 10 wt% light-burned magnesium oxide fine powder, and 4 wt% chromium-aluminum-carbon fine powder, plus 4 wt% resin. First, place the fused chromium-aluminum particles in a mixer and stir, while simultaneously adding 2.2 wt% resin at a uniform rate, continuing stirring for 10 minutes. Then, add the light-burned magnesium oxide fine powder and continue stirring for 10 minutes. Finally, add the zirconium oxide particles, the chromium oxide fine powder, the chromium-aluminum-carbon fine powder, and the remaining resin, and continue stirring for 9 minutes to obtain a mixture.

[0069] Step 2: The mixture is conditioned for 12 hours, machine-pressed at 240 MPa, and dried at 210°C for 22 hours to obtain a dried green body; the dried green body is heated to 1650°C at a rate of 4°C / min in a carbon-buried atmosphere, held for 5 hours, and cooled in the furnace to obtain a refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide.

[0070] At least two Φ36mm×36mm samples were drilled from the Cr2AlC / Mg(Al,Cr)2O4 refractory material directly bonded with chromium oxide, and buried in different coal slags as shown in Table 1. The chemical composition of coal slag 1 and coal slag 2 is detailed in Table 1. The melting area and penetration depth of the samples were tested at 1600℃ for 10 hours.

[0071] Table 1. Chemical composition (wt%) of different coal slags

[0072]

[0073]

[0074] The test results of the Cr2AlC / Mg(Al,Cr)2O4 refractory material directly bonded with chromium oxide prepared in this embodiment are shown in Table 2.

[0075] Table 2. Test results of the products manufactured in this embodiment.

[0076]

[0077] This specific implementation method has the following advantages compared with the prior art:

[0078] 1. This invention employs a mixing and milling process involving fused chromium-aluminum particles, a resin binder, and lightly calcined magnesium oxide powder. The resin binder coats the lightly calcined magnesium oxide powder onto the surface of the fused chromium-aluminum particles, enabling the preferential in-situ formation of a Cr2O3-Mg(Al,Cr)2O4 (spinel) core-shell structure during subsequent high-temperature firing. Simultaneously, the introduction of lightly calcined magnesium oxide powder into the matrix transforms the Cr2O3-Al2O3 solid solution phase in the original aggregate matrix into a Mg(Al,Cr)2O4 composite spinel phase, resulting in a spinel phase with high refractoriness and excellent thermal shock resistance (spinel thermal expansion coefficient: 8.9 × 10⁻⁶). -6 / K) is introduced into Cr2O3-Al2O3 refractory materials (chromium oxide thermal expansion coefficient: 9.0×10). -6 / K), transforming the original Cr2O3-Al2O3 solid solution bonded system between aggregate and matrix into a Cr2O3-Mg(Al,Cr)2O4 (spinel) core-shell structure aggregate-matrix bond, on the one hand, forms a high-temperature stable composite spinel bond phase between the aggregate surface and the matrix, improving the bond strength and thermal shock resistance; on the other hand, through the Mg(Al,Cr)2O4 composite spinel bond, the influence of temperature fluctuations during high-temperature service on the solid solution-desolution process of the original Cr2O3-Al2O3 solid solution on the overall high-temperature stability of the material is avoided, effectively improving the high-temperature stability of refractory materials with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide.

[0079] 2. This invention introduces the highly thermally conductive and thermally shock resistant Cr2AlC phase into the Cr2O3-Al2O3 refractory matrix. Without introducing new elements, it controls the phase composition, microstructure evolution, and expansion effect of the Cr2AlC phase during heat treatment to prepare a high-density Cr2AlC directly bonded system, thus optimizing the matrix design of the product. Simultaneously, it controls the morphology and type of the Cr2AlC secondary phase to achieve a toughening and strengthening effect on the material. Furthermore, the elemental composition of the newly introduced Cr2AlC phase is essentially consistent with the Cr2O3-Al2O3 refractory system, avoiding structural instability under high-temperature conditions caused by complex refractory phase composition. This effectively ensures the high-temperature structural stability of the refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide during slag erosion.

[0080] 3. This invention constructs a novel Cr2O3-Mg(Al,Cr)2O4 core-shell aggregate-matrix bonding morphology on the surface of Cr2O3 aggregate. Through the inducing effect of Mg(Al,Cr)2O4 composite spinel on the erosion and penetration behavior of the coal slag erosion medium (Fe, Mn ions), the penetration of coal slag is greatly reduced, improving the product's resistance to coal slag erosion. Simultaneously, it significantly reduces the valence transformation probability of Cr(III), improving environmental protection. Therefore, through the optimization of the Cr2O3-Mg(Al,Cr)2O4 core-shell aggregate-matrix interface and the construction of the matrix system, a high-strength, tough, and thermally shock resistant / coal slag resistant refractory material with direct chromium oxide bonding to Cr2AlC / Mg(Al,Cr)2O4 is ultimately obtained.

[0081] The refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide prepared in this specific embodiment is shown in the attached figure. Figure 1 The microstructure of the matrix of a refractory material prepared in Example 1, in which Cr2AlC / Mg(Al,Cr)2O4 is directly bonded to chromium oxide, after heat treatment. Figure 2 for Figure 1 The image shows the microstructure of the aggregate surface after heat treatment of refractory materials with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide. From... Figure 1 It can be seen that after high-temperature heat treatment, the layered Cr2AlC in the matrix is ​​directly bonded to Cr2O3-Al2O3; from Figure 2 It can be seen that after high-temperature heat treatment, the aggregate surface forms a distinct octahedral spinel crystal morphology.

[0082] The refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide prepared in this specific embodiment was tested and found to have the following characteristics: apparent porosity of 5.21–9.80%; and bulk density of 4.35–4.43 g / cm³. 3 The flexural strength at 1400℃ is 36.8–48.3 MPa, and the strength retention rate after three water cooling cycles from 1100℃ to 20℃ is 52%–68%. Under the erosion resistance test at 1600℃ for 10 hours, the erosion depth against coal slag 1 is 1.20–1.66 mm, and the erosion depth against coal slag 2 is 1.54–1.98 mm, with no melting loss in either case.

[0083] Therefore, this specific embodiment has the characteristics of simple process and low production energy consumption. The refractory material prepared by Cr2AlC / Mg(Al,Cr)2O4 directly combined with chromium oxide has the characteristics of excellent resistance to coal slag erosion, good thermal shock stability, excellent high temperature strength and long high temperature service life.

Claims

1. A method for preparing a refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide, characterized in that... The preparation method is as follows: Step 1: Prepare the raw materials using 55-65 wt% fused chromium aluminum particles, 5-15 wt% zirconium oxide particles, 10-20 wt% chromium oxide fine powder, 8-12 wt% light-burned magnesium oxide fine powder, and 2-8 wt% chromium aluminum carbon fine powder, plus 3-5 wt% resin. First, place the fused chromium aluminum particles in a mixer and stir, while simultaneously adding 2-2.5 wt% resin at a uniform speed, and continue stirring for 5-10 minutes. Then, add the light-burned magnesium oxide fine powder and continue stirring for 10-15 minutes. Finally, add the zirconium oxide particles, the chromium oxide fine powder, the chromium aluminum carbon fine powder, and the remaining resin, and continue stirring for 5-10 minutes to obtain a mixture. Step 2: The mixture is conditioned for 12-14 hours, machine-pressed at 200-300 MPa, and dried at 200-220℃ for 20-24 hours to obtain a dried green body; the dried green body is heated to 1600-1780℃ in a carbon-buried atmosphere at a rate of 3-5℃ / min, held for 3-6 hours, and cooled in the furnace to obtain a refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide.

2. The preparation method of the refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide according to claim 1, characterized in that: The Cr2O3 content in the fused chromium-aluminum particles is ≥98wt%, and the Al2O3 content is ≤0.3wt%; the particle size of the fused chromium-aluminum particles is 0.088mm~1.0mm.

3. The preparation method of the refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide according to claim 1, characterized in that: The zirconium oxide particles contain ≥95wt% ZrO2; the particle size of the zirconium oxide particles is 0.088mm~1mm.

4. The preparation method of the refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide according to claim 1, characterized in that: The Cr2O3 content in the chromium oxide fine powder is ≥99.5wt%; the particle size of the chromium oxide fine powder is ≤74μm.

5. The preparation method of the refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide according to claim 1, characterized in that: The MgO content in the lightly calcined magnesium oxide fine powder is ≥99.6wt%; the particle size of the lightly calcined magnesium oxide fine powder is ≤88μm.

6. The preparation method of the refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide according to claim 1, characterized in that: The Cr2AlC content in the chromium aluminum carbon fine powder is ≥99.6wt%; the particle size of the chromium aluminum carbon fine powder is ≤45μm.

7. The preparation method of the refractory material with Cr2AlC / Mg(Al,Cr)2O4 directly bonded to chromium oxide according to claim 1, characterized in that: The resin has a carbon residue rate of ≥35%; the resin is in liquid state.

8. A refractory material in which Cr2AlC / Mg(Al,Cr)2O4 is directly bonded with chromium oxide, characterized in that... The Cr2AlC / Mg(Al,Cr)2O4 directly bonded chromium oxide refractory material is the Cr2AlC / Mg(Al,Cr)2O4 directly bonded chromium oxide refractory material prepared by the preparation method of the Cr2AlC / Mg(Al,Cr)2O4 directly bonded chromium oxide refractory material according to any one of claims 1 to 7.

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