A high-toughness magnesium-aluminum spinel refractory material and preparation method thereof

Abstract

The present invention relates to a high-toughness magnesium-aluminum spinel refractory material and a preparation method thereof. The high-toughness magnesium-aluminum spinel raw material is the following materials by weight: 10 to 20 parts of magnesium-aluminum spinel particles with a particle size of 3 to 5 mm, 20 to 40 parts of magnesium-aluminum spinel particles with a particle size of 1 to 3 mm, 10 to 20 parts of magnesium-aluminum spinel particles with a particle size of 0.088 to 1 mm, and 30 to 50 parts of magnesium-aluminum spinel fine powder with a particle size of less than 0.088, and 5 to 10 parts of a binder. The above materials are mixed and formed by cold isostatic pressing, and then the formed object is immersed in a lanthanum nitrate aqueous solution with a concentration of 30 to 70%. The lanthanum nitrate introduced by the present invention decomposes rare earth lanthanum ions during high-temperature cracking, which can react with magnesium-aluminum spinel to form lanthanum hexaaluminate with a flaky structure, which is evenly distributed between magnesium-aluminum spinel grains, effectively improving the fracture toughness and thermal shock stability of the material.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnesium-aluminum spinel refractory materials, and specifically relates to a high-toughness magnesium-aluminum spinel refractory material and a preparation method thereof. Background Art

[0002] Magnesia-alumina spinel refractory materials are often used in cement kilns, nonferrous metallurgy and other fields due to their high high temperature strength, high refractoriness under load, good thermal shock resistance and excellent alkaline slag resistance. However, there are a certain amount of impurities in the raw materials, which affect the high temperature structural stability and fracture toughness of the refractory materials, and further affect the thermal shock stability and service life of the refractory materials.

[0003] In order to give spinel refractory properties, attempts have been made to add some substances to the refractory, as reported below:

[0004] Adding sodium: such as the patented technology of "Preparation method of high thermal shock magnesium aluminum spinel refractory with lamellar crystals at grain boundaries" (CN117209266A), which adds sodium-containing additives and impurity phases at the grain boundaries to form a liquid phase to dissolve magnesium aluminum spinel and slowly crystallize, and through epitaxial growth at the grain boundaries, lamellar crystals NMA are grown at the grain boundaries to separate the grain boundaries. Although it is beneficial to improve the thermal shock stability of magnesium aluminum spinel refractory materials, the addition of sodium impurities greatly reduces its high-temperature structural stability.

[0005] Adding yttrium and zirconium, etc.: For example, the patented technology of "A magnesium aluminum spinel material and its preparation method and application" (CN117024132A) adds zirconium oxide and boride as mineralizers, and prepares magnesium aluminum spinel material with high thermal shock stability through high-temperature sintering. Although it has good thermal shock stability, yttrium oxide and zirconium boride fine powders are difficult to disperse evenly in the material, resulting in uncontrollable material performance.

[0006] Adding boron: such as the patented technology of "A magnesium-aluminum spinel refractory material and its preparation method" (CN113582709A), which adds magnesium powder, aluminum powder, titanium dioxide powder and boron trioxide powder as raw materials, and synthesizes a mixture of magnesium-aluminum spinel and titanium diboride through combustion and chemical reaction.

[0007] Material purification: such as the patented technology of "A high-purity aluminum-magnesium spinel brick refractory material for float glass all-oxygen combustion melting furnace" (CN102531646A), which uses ultra-high purity aluminum-magnesium spinel aggregate, ultra-high purity aluminum-magnesium spinel fine powder and high-purity alumina micropowder as raw materials to prepare magnesium-aluminum spinel refractory materials.

[0008] Adding manganese: such as the patented technology of "A manganese-containing magnesia-alumina spinel refractory" (CN105777151A), which prepares magnesia-alumina spinel refractory by adding manganese dioxide and metallic manganese powder to the magnesia-alumina spinel refractory to form a magnesium-manganese solid solution.

[0009] Although the above method solves the problem of stability, the refractory material prepared has poor toughness.

[0010] Since rare earths have the advantages of high melting point and high chemical activity, they have good corrosion resistance and can react with other metal oxides to form composite oxides to improve material properties. In order to change the toughness of magnesium-aluminum spinel refractory materials, we tried to add rare earth elements to magnesium-aluminum spinel materials, and found that the toughness of the materials can be improved to varying degrees, among which lanthanum as an additive has the best performance.

[0011] There are many solutions for adding lanthanum in the prior art, each with different effects:

[0012] Lanthanum metal promotes the formation of a dense layer of magnesium oxide: For example, in the "Method for preparing a magnesium-aluminum spinel-carbon refractory material with rare earth as an antioxidant" (CN117720341A), lanthanum metal is mixed with fused magnesium-aluminum spinel aggregate, fused magnesium-aluminum spinel fine powder, flake graphite, and phenolic resin, and then fully smelted. Lanthanum is used in this patent, and lanthanum metal acts as an antioxidant because lanthanum metal is chemically active and easy to react with oxygen and can be used as an antioxidant; the introduction of rare earth lanthanum not only delays the oxidation of carbon, but also promotes the formation of a dense layer of magnesium oxide in the magnesium-aluminum spinel material.

[0013] Lanthanum metal forms a protective layer: such as "A magnesium-aluminum spinel molded crucible and its manufacturing method" (CN115231916A), lanthanum oxide powder is also added in the present invention. Since lanthanum is more active than the elements in NdFeB, during the sintering process of the crucible, magnesium-aluminum spinel reacts with lanthanum oxide powder to form a replacement reaction protective layer, which can prevent NdFeB from having a replacement reaction with the crucible.

[0014] Lanthanum oxide increases toughness and thermal shock resistance: such as "A magnesium aluminum spinel refractory material and its preparation method" (CN112010659A), the solution is to mix all the materials and then refine them. Among them, lanthanum oxide and cerium oxide can improve the strength of the refractory material, enhance its toughness and hardness, thereby enhancing the wear resistance of the refractory material, and lanthanum oxide, cerium oxide and hollow glass microspheres can reduce the thermal conductivity of the refractory material, and synergistically with silicon carbide, which can not only enhance the thermal shock resistance of the refractory reinforcement material, but also improve the strength of the refractory material;

[0015] For example, in "a silicon carbide composite refractory product containing rare earth oxides" (CN111620709A), the introduction of lanthanum oxide will generate a rare earth binding phase magnesium-based lanthanum hexaaluminate (LaMgAl 11 O 19 ), and it has a unique structure with four aluminum spinel layers inlaid on its surface. This structure can significantly reduce the diffusion of oxygen ions, thereby improving the antioxidant properties of the bottom layer and matrix of the material; in addition, magnesium-based lanthanum hexaaluminate has low thermal conductivity and thermal stability in a relatively high temperature environment.

[0016] In the above methods, the metal lanthanum or lanthanum oxide is added by directly mixing it with the material and then refining it.

[0017] Based on the advantages of lanthanum, the inventors considered adding lanthanum to magnesium-aluminum spinel refractory materials. Metallic lanthanum or lanthanum oxide is a solid material. When added to the refractory material, it is easy to cause uneven distribution of lanthanum due to uneven mixing. Considering introducing lanthanum in the form of lanthanum nitrate aqueous solution, the present invention was obtained. Summary of the invention

[0018] In order to improve the fracture toughness and high-temperature structural stability of magnesia-alumina spinel materials and reduce the unevenness when lanthanum is introduced, the inventors provide a high-toughness magnesia-alumina spinel refractory material.

[0019] The invention provides a high-toughness magnesium-aluminum spinel refractory material, the raw materials of which are the following materials in parts by weight: 10 to 20 parts of magnesium-aluminum spinel particles with a particle size of 3 to 5 mm, 20 to 40 parts of magnesium-aluminum spinel particles with a particle size of 1 to 3 mm, 10 to 20 parts of magnesium-aluminum spinel particles with a particle size of 0.088 to 1 mm, 30 to 50 parts of magnesium-aluminum spinel fine powder with a particle size of less than 0.088, and 5 to 10 parts of a binder. The materials are formed by cold isostatic pressing, and then the formed object is immersed in a lanthanum nitrate aqueous solution with a concentration of 30 to 70%.

[0020] Preferably, the concentration of the lanthanum nitrate aqueous solution is 40-60%, or the concentration of the lanthanum nitrate aqueous solution is 40-55%;

[0021] More preferably, the concentration of the lanthanum nitrate aqueous solution is 50-55%.

[0022] The cold isostatic pressing comprises mixing magnesium-aluminum spinel particles of different particle sizes, adding a binder, placing the mixture in a mold, sealing it, and moving it to a pressure chamber of an isostatic press, first increasing the pressure to 30-50 MPa at a rate of 0.1-4 MPa / s, increasing the pressure to 60-80 MPa at a rate of 0.1-5 MPa / s, increasing the pressure to 90-110 MPa at a rate of 0.1-10 MPa / s, increasing the pressure to 120-140 MPa at a rate of 0.1-6 MPa / s, and increasing the pressure to 150-160 MPa at a rate of 0.1-10 MPa / s. ~8MPa / s to 150~200MPa, maintain the pressure for 1~5min; then reduce the pressure to 120~140MPa at a rate of 0.1~5MPa / s, reduce the pressure to 90~110MPa at a rate of 0.1~6MPa / s, reduce the pressure to 60~80MPa at a rate of 0.1~8MPa / s, reduce the pressure to 30~50MPa at a rate of 0.1~5MPa / s, and reduce the pressure to 2MPa at a rate of 0.1~5MPa / s; finally unload to normal pressure.

[0023] Preferably, the raw materials of the high-toughness magnesia-alumina spinel refractory material are the following materials in parts by weight: 12 to 18 parts of magnesia-alumina spinel particles with a particle size of 3 to 5 mm, 25 to 35 parts of magnesia-alumina spinel particles with a particle size of 1 to 3 mm, 12 to 18 parts of magnesia-alumina spinel particles with a particle size of 0.088 to 1 mm and 35 to 45 parts of magnesia-alumina spinel fine powder with a particle size of less than 0.088, and 5 to 10 parts of a binder.

[0024] Further preferably, the raw materials of the high-toughness magnesia-alumina spinel refractory material are the following materials in parts by weight: 15 parts of magnesia-alumina spinel particles with a particle size of 3~5mm, 30 parts of magnesia-alumina spinel particles with a particle size of 1~3mm, 15 parts of magnesia-alumina spinel particles with a particle size of 0.088~1mm and 40 parts of magnesia-alumina spinel fine powder with a particle size of less than 0.088, and 5~10 parts of adhesive.

[0025] In the above-mentioned high toughness magnesia-alumina spinel refractory material:

[0026] The chemical composition of the magnesium aluminum spinel particles is: MgO = 10 ~ 15wt%, Al 2 O 3 =85~90wt%, CaO≤0.7wt%, SiO 2 ≤0.6wt%Fe 2 O 3 ≤0.5wt%.

[0027] The chemical composition of the magnesium aluminum spinel fine powder is: MgO = 10 ~ 15wt%, Al 2 O 3 =85~90wt%, CaO≤0.7wt%, SiO 2≤0.6wt%Fe 2 O 3 ≤0.5wt%.

[0028] The adhesive is a polyvinyl alcohol aqueous solution with a concentration of 10%.

[0029] The present invention also provides a method for preparing a high-toughness magnesium-aluminum spinel refractory material, which comprises the following steps:

[0030] Step 1, mixing magnesium-aluminum spinel particles of different particle sizes;

[0031] Step 2: Add adhesive and perform cold isostatic pressing;

[0032] Step 3, drying, and then heat treating to obtain a matrix;

[0033] Step 4: immersing the substrate in a lanthanum nitrate aqueous solution under vacuum pressure, and then performing a cracking reaction;

[0034] Step 5: calcining to obtain high-toughness magnesia-alumina spinel refractory material.

[0035] In the above method,

[0036] In step 2:

[0037] The cold isostatic pressing molding comprises placing the mixed material in a mold, sealing the mold, and moving the mold into a pressure chamber of an isostatic press. The pressure is first increased to 30-50 MPa at a rate of 0.1-4 MPa / s, then to 60-80 MPa at a rate of 0.1-5 MPa / s, then to 90-110 MPa at a rate of 0.1-10 MPa / s, then to 120-140 MPa at a rate of 0.1-6 MPa / s, then to 120-140 MPa at a rate of 0.1-8 MPa / s. To 150~200MPa, maintain the pressure for 1~5min; then reduce the pressure to 120~140MPa at a rate of 0.1~5MPa / s, reduce the pressure to 90~110MPa at a rate of 0.1~6MPa / s, reduce the pressure to 60~80MPa at a rate of 0.1~8MPa / s, reduce the pressure to 30~50MPa at a rate of 0.1~5MPa / s, and reduce the pressure to 2MPa at a rate of 0.1~5MPa / s; finally unload to normal pressure.

[0038] Preferably, the cold isostatic pressing molding: the mixture is placed in a mold, sealed, and moved to a pressure chamber of an isostatic press, and the pressure is first increased to 50 MPa at a rate of 3-4 MPa / s, then to 80 MPa at a rate of 4-5 MPa / s, then to 90-110 MPa at a rate of 5-10 MPa / s, then to 120-140 MPa at a rate of 5-6 MPa / s, then to 6-8 MPa / s. To 150~200MPa, maintain the pressure for 3~5min; then reduce the pressure to 120~140MPa at a rate of 3~5MPa / s, reduce the pressure to 90~110MPa at a rate of 5~6MPa / s, reduce the pressure to 60~80MPa at a rate of 5~8MPa / s, reduce the pressure to 30~50MPa at a rate of 4~5MPa / s, and reduce the pressure to 2MPa at a rate of 5MPa / s; finally unload to normal pressure.

[0039] In step three:

[0040] The drying is performed at 100-120° C. for 12-36 hours;

[0041] The heat treatment condition is 1400-1600°C for 2-5 hours;

[0042] In step 4:

[0043] When soaking under the vacuum pressure, the vacuum degree is 10 -3 ~10 -2 MPa, pressure is 5~8MPa, pressure is maintained for 4~8 hours;

[0044] The pyrolysis is carried out at 800-1200° C. for 1-3 hours.

[0045] Five steps:

[0046] The calcination conditions are: temperature 1600-1800°C, time 3-5 hours.

[0047] Specifically, the preparation method of high-toughness magnesium-aluminum spinel refractory material comprises the following steps:

[0048] Step 1: Mix and grind 15 wt% of magnesia-alumina spinel particles with a particle size of 3-5 mm, 30 wt% of magnesia-alumina spinel particles with a particle size of 1-3 mm, 15 wt% of magnesia-alumina spinel particles with a particle size of 0.088-1 mm, and 40 wt% of magnesia-alumina spinel fine powder with a particle size of less than 0.088 for 30 minutes to obtain a mixed magnesia-alumina spinel raw material;

[0049] Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material with a 5-10 wt% polyvinyl alcohol aqueous solution, and perform cold isostatic pressing to obtain a magnesium-aluminum spinel refractory material embryo;

[0050] The cold isostatic pressing molding comprises placing the mixed material in a mold, sealing the mold, and moving the mold into a pressure chamber of an isostatic press. The pressure is first increased to 30-50 MPa at a rate of 0.1-4 MPa / s, then to 60-80 MPa at a rate of 0.1-5 MPa / s, then to 90-110 MPa at a rate of 0.1-10 MPa / s, then to 120-140 MPa at a rate of 0.1-6 MPa / s, then to 120-140 MPa at a rate of 0.1-8 MPa / s. To 150~200MPa, maintain the pressure for 1~5min; then reduce the pressure to 120~140MPa at a rate of 0.1~5MPa / s, reduce the pressure to 90~110MPa at a rate of 0.1~6MPa / s, reduce the pressure to 60~80MPa at a rate of 0.1~8MPa / s, reduce the pressure to 30~50MPa at a rate of 0.1~5MPa / s, and reduce the pressure to 2MPa at a rate of 0.1~5MPa / s; finally unload to normal pressure;

[0051] Step 3, drying the magnesia-alumina spinel refractory material embryo at 110-120° C. for 12-36 hours, and heat treating at 1400-1600° C. for 2-5 hours to obtain a magnesia-alumina spinel refractory material matrix;

[0052] Step 4: Place the magnesium aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution and place it in a vacuum of 10 -3 ~10 -2 MPa and a pressure of 5 to 8 MPa for 4 to 8 hours; then high-temperature cracking at 800 to 1200°C for 1 to 3 hours to obtain a pretreated magnesium-aluminum spinel refractory material matrix;

[0053] Step 5: calcining the pretreated magnesia-alumina spinel refractory material matrix at 1600-1800° C. for 3-5 hours to obtain a high-toughness magnesia-alumina spinel refractory material.

[0054] Due to the adoption of the above technical solution, the present invention has the following positive effects compared with the prior art:

[0055] 1. In order to increase the toughness of magnesium-aluminum spinel refractory materials, the inventors considered adding lanthanum to the existing magnesium-aluminum spinel aggregates and fine powders. Metallic lanthanum and lanthanum oxide are conventional products in the field of materials. However, when added to the preparation of refractory materials, uneven mixing often causes uneven distribution of lanthanum, which not only lacks toughness, but also causes the magnesium-aluminum spinel refractory materials to expand, which runs counter to the purpose of the present invention.

[0056] Lanthanum nitrate aqueous solution is a liquid, and liquids are easier to disperse evenly than solids, so we thought of using lanthanum nitrate aqueous solution.

[0057] When screening the dosage, the concentration affects the dosage of lanthanum nitrate because it is immersed in the solution. When the dosage of lanthanum nitrate is too little, it cannot increase the toughness, and too much will cause the destruction of the spinel structure. Finally, the concentration of the lanthanum nitrate aqueous solution was determined to be 30~70%.

[0058] 2. Preparation method:

[0059] The inventors have tried to directly refine the lanthanum nitrate aqueous solution with other aggregates (granular materials) and powders. Mixing the lanthanum nitrate aqueous solution directly with the aggregate powder will make it difficult to shape (just like too much water in the mud, it cannot be kneaded into a block), and it is difficult to refine in the later stage;

[0060] Through the control of the cold isostatic pressing method of the present invention, the matrix is ​​relatively dense, and there are gaps in the middle where the lanthanum nitrate aqueous solution can be soaked. Under the existence of a certain vacuum degree and pressure, the lanthanum nitrate can be better penetrated into the matrix to achieve the purpose of uniform distribution of lanthanum.

[0061] 3. The lanthanum nitrate introduced in the present invention decomposes rare earth lanthanum ions during the high-temperature cracking process, which can effectively absorb impurities such as calcium and silicon in the raw materials and convert them into a high-melting-point rare earth calcium silicate composite phase, greatly improving the high-temperature structural stability of the magnesium-aluminum spinel refractory material.

[0062] The lanthanum nitrate introduced in the present invention decomposes rare earth lanthanum ions during high-temperature cracking, and can react with magnesium-aluminum spinel to form lanthanum hexaaluminate with a flaky structure, which is evenly distributed between magnesium-aluminum spinel grains, effectively improving the fracture toughness and thermal shock stability of the material.

[0063] 4. The high-toughness magnesium-aluminum spinel refractory prepared by the present invention has been tested: the high-temperature structure is stable; the fracture toughness is 11.8~18.7MPa·m 1 / 2 ;The thermal shock stability (1000℃ / water cooling) cycle number is 42~60 times.

[0064] 5. The method provided by the present invention has low equipment requirements and simple process. The prepared high-toughness magnesium-aluminum spinel refractory material has excellent high-temperature structural stability, very good high fracture toughness and excellent thermal shock stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 : SEM image of magnesium-aluminum spinel refractory material without adding lanthanum nitrate (Comparative Example 1);

[0066] Figure 2 : SEM image of magnesium-aluminum spinel refractory material (Comparative Example 3) with addition of lanthanum nitrate aqueous solution but without cold isostatic pressing;

[0067] Figure 3: SEM image of the magnesium-aluminum spinel refractory material (Example 1) to which lanthanum nitrate aqueous solution (concentration of 50%) is added;

[0068] Figure 4 : XRD diagrams of magnesia-alumina spinel refractory materials with addition of lanthanum nitrate aqueous solution (concentration of 50%) (Example 1) and without addition of lanthanum nitrate (Comparative Example 1), wherein the upper figure is Example 1 and the lower figure is Comparative Example 1. DETAILED DESCRIPTION

[0069] The present invention is further described below in conjunction with specific embodiments, but is not intended to limit the scope of protection thereof:

[0070] In this specific implementation mode:

[0071] The chemical composition of the magnesium aluminum spinel particles is: MgO = 10 ~ 15wt%, Al 2 O 3 =85~90wt%, CaO≤0.7wt%, SiO 2 ≤0.6wt%Fe 2 O 3 ≤0.5wt%.

[0072] The chemical composition of the magnesium aluminum spinel fine powder is: MgO = 10 ~ 15wt%, Al 2 O 3 =85~90wt%, CaO≤0.7wt%, SiO 2 ≤0.6wt%Fe 2 O 3 ≤0.5wt%.

[0073] The concentration of the polyvinyl alcohol aqueous solution is 10%, and the preparation method is: dissolve 10g of polyvinyl alcohol in 90g of water, and stir evenly to obtain the solution.

[0074] The concentration of the lanthanum nitrate aqueous solution is 50%, and the preparation method is: dissolve 50g of lanthanum nitrate in 50g of water, and stir evenly to obtain the solution.

[0075] Example 1: A high-toughness magnesium-aluminum spinel refractory material and a preparation method thereof

[0076] 1. Raw materials: combination of magnesia-alumina spinel particles: 15 kg of magnesia-alumina spinel particles with a particle size of 3-5 mm, 30 kg of magnesia-alumina spinel particles with a particle size of 1-3 mm, 15 kg of magnesia-alumina spinel particles with a particle size of 0.088-1 mm and 40 kg of magnesia-alumina spinel fine powder with a particle size of less than 0.088; binder, 5 kg of polyvinyl alcohol aqueous solution; add lanthanum nitrate aqueous solution with a concentration of 50%, the amount of which is enough to immerse the refractory matrix.

[0077] 2. Preparation method:

[0078] Step 1, placing magnesium aluminum spinel particles with a particle size of 3-5 mm, magnesium aluminum spinel particles with a particle size of 1-3 mm, magnesium aluminum spinel particles with a particle size of 0.088-1 mm and magnesium aluminum spinel fine powder with a particle size of less than 0.088 in a mixing mill and mixing for 30 minutes to obtain a magnesium aluminum spinel raw material after mixing;

[0079] Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material and the polyvinyl alcohol aqueous solution, and perform cold isostatic pressing to obtain a magnesium-aluminum spinel refractory material embryo;

[0080] The cold isostatic pressing molding: placing the mixed material in a mold, sealing it, and moving it to a pressure chamber of an isostatic press, first increasing the pressure to 50MPa at a rate of 3MPa / s, increasing the pressure to 80MPa at a rate of 4MPa / s, increasing the pressure to 90MPa at a rate of 5MPa / s, increasing the pressure to 120MPa at a rate of 5MPa / s, and increasing the pressure to 150MPa at a rate of 6MPa / s, and maintaining the pressure for 1 minute; then reducing the pressure to 140MPa at a rate of 3MPa / s, reducing the pressure to 110MPa at a rate of 6MPa / s, reducing the pressure to 80MPa at a rate of 8MPa / s, reducing the pressure to 50MPa at a rate of 5MPa / s, and reducing the pressure to 2MPa at a rate of 5MPa / s; and finally unloading to normal pressure;

[0081] Step 3, drying the magnesium-aluminum spinel refractory material embryo at 110° C. for 24 hours, and heat treating at 1400° C. for 3 hours to obtain a magnesium-aluminum spinel refractory material matrix;

[0082] Step 4: Place the magnesium-aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution (concentration of 50%) and place it in a vacuum of 10 -2 MPa and the pressure is 8MPa for 4 hours; then the pyrolysis is carried out at 1000°C for 3 hours to obtain a pretreated magnesium-aluminum spinel refractory matrix;

[0083] Step 5: calcining the pretreated magnesia-alumina spinel refractory material matrix at 1600° C. for 3 hours to obtain a high-toughness magnesia-alumina spinel refractory material.

[0084] Example 2: A high-toughness magnesium-aluminum spinel refractory material and its preparation method

[0085] 1. Raw materials are the same as those in Example 1, except that the amount of polyvinyl alcohol aqueous solution is 10 kg;

[0086] 2. The preparation steps are:

[0087] Step 1, placing magnesium aluminum spinel particles with a particle size of 3-5 mm, magnesium aluminum spinel particles with a particle size of 1-3 mm, magnesium aluminum spinel particles with a particle size of 0.088-1 mm and magnesium aluminum spinel fine powder with a particle size of less than 0.088 in a mixing mill and mixing for 30 minutes to obtain a magnesium aluminum spinel raw material after mixing;

[0088] Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material and the polyvinyl alcohol aqueous solution, and perform cold isostatic pressing to obtain a magnesium-aluminum spinel refractory material embryo;

[0089] The cold isostatic pressing molding comprises placing the mixed material in a mold, sealing the mold, and moving the mixed material into a pressure chamber of an isostatic press. The mixed material is firstly pressurized to 50MPa at a rate of 4MPa / s, then to 80MPa at a rate of 5MPa / s, then to 110MPa at a rate of 10MPa / s, then to 140MPa at a rate of 6MPa / s, then to 200MPa at a rate of 8MPa / s, and the pressure is maintained for 5 minutes. The mixed material is then pressurized to 140MPa at a rate of 5MPa / s, then to 110MPa at a rate of 6MPa / s, then to 80MPa at a rate of 8MPa / s, then to 50MPa at a rate of 5MPa / s, and finally to 2MPa at a rate of 5MPa / s. The mixed material is then unloaded to normal pressure.

[0090] Step 3, drying the magnesium-aluminum spinel refractory material embryo at 110° C. for 24 hours, and heat treating at 1600° C. for 3 hours to obtain a magnesium-aluminum spinel refractory material matrix;

[0091] Step 4: Place the magnesium-aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution (concentration of 50%) and place it in a vacuum of 10 -3 MPa and the pressure is 8MPa, and the pressure is maintained for 8 hours; then, the pre-treated magnesium-aluminum spinel refractory matrix is ​​obtained by high temperature cracking at 1000°C for 3 hours;

[0092] Step 5: calcining the pretreated magnesia-alumina spinel refractory material matrix at 1800° C. for 5 hours to obtain a high-toughness magnesia-alumina spinel refractory material.

[0093] Example 3: A high-toughness magnesium-aluminum spinel refractory material and its preparation method

[0094] 1. Raw materials are the same as those in Example 1, except that the amount of polyvinyl alcohol aqueous solution is 10 kg;

[0095] 2. The preparation steps are:

[0096] Step 1, placing magnesium aluminum spinel particles with a particle size of 3-5 mm, magnesium aluminum spinel particles with a particle size of 1-3 mm, magnesium aluminum spinel particles with a particle size of 0.088-1 mm and magnesium aluminum spinel fine powder with a particle size of less than 0.088 in a mixing mill and mixing for 30 minutes to obtain a magnesium aluminum spinel raw material after mixing;

[0097] Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material and the polyvinyl alcohol aqueous solution, and perform cold isostatic pressing to obtain a magnesium-aluminum spinel refractory material embryo;

[0098] The cold isostatic pressing molding comprises placing the mixed material in a mold, sealing the mold, and moving the mixed material into a pressure chamber of an isostatic press. The mixed material is firstly pressurized to 50MPa at a rate of 4MPa / s, then to 80MPa at a rate of 5MPa / s, then to 90MPa at a rate of 5MPa / s, then to 140MPa at a rate of 5MPa / s, then to 200MPa at a rate of 8MPa / s, and the pressure is maintained for 5 minutes. The mixed material is then pressurized to 140MPa at a rate of 5MPa / s, then to 110MPa at a rate of 5MPa / s, then to 80MPa at a rate of 5MPa / s, then to 50MPa at a rate of 4MPa / s, and finally to 2MPa at a rate of 5MPa / s. The mixed material is then unloaded to normal pressure.

[0099] Step 3, drying the magnesium-aluminum spinel refractory material embryo at 110° C. for 24 hours, and heat treating at 1600° C. for 3 hours to obtain a magnesium-aluminum spinel refractory material matrix;

[0100] Step 4: Place the magnesium-aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution (concentration of 50%) and place it in a vacuum of 10 -2 MPa and the pressure is 8MPa, and the pressure is maintained for 8 hours; then, the pre-treated magnesium-aluminum spinel refractory matrix is ​​obtained by high temperature cracking at 1000°C for 3 hours;

[0101] Step 5: calcining the pretreated magnesia-alumina spinel refractory material matrix at 1800° C. for 4 hours to obtain a high-toughness magnesia-alumina spinel refractory material.

[0102] Example 4: A high-toughness magnesium-aluminum spinel refractory material and its preparation method

[0103] 1. Raw materials are the same as those in Example 1, except that the amount of polyvinyl alcohol aqueous solution is 10 kg;

[0104] 2. The preparation steps are:

[0105] Step 1, placing magnesium aluminum spinel particles with a particle size of 3-5 mm, magnesium aluminum spinel particles with a particle size of 1-3 mm, magnesium aluminum spinel particles with a particle size of 0.088-1 mm and magnesium aluminum spinel fine powder with a particle size of less than 0.088 in a mixing mill and mixing for 30 minutes to obtain a magnesium aluminum spinel raw material after mixing;

[0106] Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material and the polyvinyl alcohol aqueous solution, and perform cold isostatic pressing to obtain a magnesium-aluminum spinel refractory material embryo;

[0107] The cold isostatic pressing molding comprises placing the mixed material in a mold, sealing the mold, and moving the mixed material into a pressure chamber of an isostatic press. The mixed material is firstly pressurized to 50MPa at a rate of 4MPa / s, then to 80MPa at a rate of 5MPa / s, then to 110MPa at a rate of 10MPa / s, then to 140MPa at a rate of 5MPa / s, then to 200MPa at a rate of 8MPa / s, and the pressure is maintained for 3 minutes. The mixed material is then pressurized to 140MPa at a rate of 5MPa / s, then to 110MPa at a rate of 6MPa / s, then to 80MPa at a rate of 8MPa / s, then to 50MPa at a rate of 5MPa / s, and finally to 2MPa at a rate of 5MPa / s. The mixed material is then unloaded to normal pressure.

[0108] Step 3, drying the magnesium-aluminum spinel refractory material embryo at 110° C. for 24 hours, and heat treating at 1600° C. for 3 hours to obtain a magnesium-aluminum spinel refractory material matrix;

[0109] Step 4: Place the magnesium-aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution (concentration of 50%) and place it in a vacuum of 10 -2 MPa and the pressure is 8MPa, and the pressure is maintained for 8 hours; then, the pre-treated magnesium-aluminum spinel refractory matrix is ​​obtained by high temperature cracking at 1000°C for 3 hours;

[0110] Step 5: calcining the pretreated magnesia-alumina spinel refractory material matrix at 1800° C. for 3 hours to obtain a high-toughness magnesia-alumina spinel refractory material.

[0111] Example 5: A high-toughness magnesium-aluminum spinel refractory material and its preparation method

[0112] 1. Raw materials are the same as those in Example 1, except that the amount of polyvinyl alcohol aqueous solution is 5 kg;

[0113] 2. The preparation steps are:

[0114] Step 1, placing magnesium aluminum spinel particles with a particle size of 3-5 mm, magnesium aluminum spinel particles with a particle size of 1-3 mm, magnesium aluminum spinel particles with a particle size of 0.088-1 mm and magnesium aluminum spinel fine powder with a particle size of less than 0.088 in a mixing mill and mixing for 30 minutes to obtain a magnesium aluminum spinel raw material after mixing;

[0115] Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material and the polyvinyl alcohol aqueous solution, and perform cold isostatic pressing to obtain a magnesium-aluminum spinel refractory material embryo;

[0116] The cold isostatic pressing molding comprises placing the mixed material in a mold, sealing the mold, and moving the mixed material into a pressure chamber of an isostatic press. The mixed material is firstly pressurized to 50MPa at a rate of 4MPa / s, then to 80MPa at a rate of 5MPa / s, then to 110MPa at a rate of 10MPa / s, then to 140MPa at a rate of 6MPa / s, then to 200MPa at a rate of 8MPa / s, and the pressure is maintained for 5 minutes. The mixed material is then pressurized to 140MPa at a rate of 5MPa / s, then to 110MPa at a rate of 6MPa / s, then to 80MPa at a rate of 8MPa / s, then to 50MPa at a rate of 5MPa / s, and finally to 2MPa at a rate of 5MPa / s. The mixed material is then unloaded to normal pressure.

[0117] Step 3, drying the magnesium-aluminum spinel refractory material embryo at 110° C. for 24 hours, and heat treating at 1500° C. for 3 hours to obtain a magnesium-aluminum spinel refractory material matrix;

[0118] Step 4: Place the magnesium-aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution (concentration of 50%) and place it in a vacuum of 10 -2 MPa and the pressure is 8MPa, and the pressure is maintained for 8 hours; then, the pre-treated magnesium-aluminum spinel refractory matrix is ​​obtained by high temperature cracking at 1000°C for 3 hours;

[0119] Step 5: calcining the pretreated magnesia-alumina spinel refractory material matrix at 1800° C. for 3 hours to obtain a high-toughness magnesia-alumina spinel refractory material.

[0120] Example 6: A high-toughness magnesium-aluminum spinel refractory material and its preparation method

[0121] 1. Raw materials are the same as those in Example 1, except that the amount of polyvinyl alcohol aqueous solution is 8 kg;

[0122] 2. The preparation steps are:

[0123] Step 1, placing magnesium aluminum spinel particles with a particle size of 3-5 mm, magnesium aluminum spinel particles with a particle size of 1-3 mm, magnesium aluminum spinel particles with a particle size of 0.088-1 mm and magnesium aluminum spinel fine powder with a particle size of less than 0.088 in a mixing mill and mixing for 30 minutes to obtain a magnesium aluminum spinel raw material after mixing;

[0124] Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material and the polyvinyl alcohol aqueous solution, and perform cold isostatic pressing to obtain a magnesium-aluminum spinel refractory material embryo;

[0125] The cold isostatic pressing molding comprises placing the mixed material in a mold, sealing the mold, and moving the mixed material into a pressure chamber of an isostatic press. The mixed material is firstly pressurized to 50MPa at a rate of 4MPa / s, then to 80MPa at a rate of 5MPa / s, then to 110MPa at a rate of 10MPa / s, then to 140MPa at a rate of 6MPa / s, then to 200MPa at a rate of 8MPa / s, and the pressure is maintained for 5 minutes. The mixed material is then pressurized to 140MPa at a rate of 5MPa / s, then to 110MPa at a rate of 6MPa / s, then to 80MPa at a rate of 8MPa / s, then to 50MPa at a rate of 5MPa / s, and finally to 2MPa at a rate of 5MPa / s. The mixed material is then unloaded to normal pressure.

[0126] Step 3, drying the magnesium-aluminum spinel refractory material embryo at 110° C. for 24 hours, and heat treating at 1600° C. for 3 hours to obtain a magnesium-aluminum spinel refractory material matrix;

[0127] Step 4: Place the magnesium-aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution (concentration of 50%) and place it in a vacuum of 10 -2 MPa (different from Example 2) and the pressure is 8MPa for 8 hours; then the high temperature cracking is carried out at 1000°C for 3 hours to obtain the pretreated magnesium-aluminum spinel refractory matrix;

[0128] Step 5: calcining the pretreated magnesia-alumina spinel refractory material matrix at 1800° C. for 3 hours to obtain a high-toughness magnesia-alumina spinel refractory material.

[0129] Example 7: A high-toughness magnesium-aluminum spinel refractory material and a preparation method thereof.

[0130] 1. Raw materials: Same as Example 1, except that the concentration of lanthanum nitrate aqueous solution is 40%

[0131] 2. Preparation method:

[0132] Step 1, placing magnesium aluminum spinel particles with a particle size of 3-5 mm, magnesium aluminum spinel particles with a particle size of 1-3 mm, magnesium aluminum spinel particles with a particle size of 0.088-1 mm and magnesium aluminum spinel fine powder with a particle size of less than 0.088 in a mixing mill and mixing for 30 minutes to obtain a magnesium aluminum spinel raw material after mixing;

[0133] Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material and the polyvinyl alcohol aqueous solution, and perform cold isostatic pressing to obtain a magnesium-aluminum spinel refractory material embryo;

[0134] The cold isostatic pressing molding: placing the mixed material in a mold, sealing it, and moving it to a pressure chamber of an isostatic press, first increasing the pressure to 50MPa at a rate of 3MPa / s, increasing the pressure to 80MPa at a rate of 4MPa / s, increasing the pressure to 90MPa at a rate of 5MPa / s, increasing the pressure to 120MPa at a rate of 5MPa / s, and increasing the pressure to 150MPa at a rate of 6MPa / s, and maintaining the pressure for 1 minute; then reducing the pressure to 140MPa at a rate of 3MPa / s, reducing the pressure to 110MPa at a rate of 6MPa / s, reducing the pressure to 80MPa at a rate of 8MPa / s, reducing the pressure to 50MPa at a rate of 5MPa / s, and reducing the pressure to 2MPa at a rate of 5MPa / s; and finally unloading to normal pressure;

[0135] Step 3, drying the magnesium-aluminum spinel refractory material embryo at 110° C. for 24 hours, and heat treating at 1400° C. for 3 hours to obtain a magnesium-aluminum spinel refractory material matrix;

[0136] Step 4: Place the magnesium aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution (concentration 30%) and place it in a vacuum of 10 -2 MPa and the pressure is 8MPa for 4 hours; then the pyrolysis is carried out at 1000°C for 3 hours to obtain a pretreated magnesium-aluminum spinel refractory matrix;

[0137] Step 5: calcining the pretreated magnesia-alumina spinel refractory material matrix at 1600° C. for 3 hours to obtain a high-toughness magnesia-alumina spinel refractory material.

[0138] Example 8: A high-toughness magnesium-aluminum spinel refractory material and its preparation method

[0139] 1. Raw materials: Same as Example 1, except that the concentration of the lanthanum nitrate aqueous solution is 55%.

[0140] 2. Preparation method:

[0141] Step 1, placing magnesium aluminum spinel particles with a particle size of 3-5 mm, magnesium aluminum spinel particles with a particle size of 1-3 mm, magnesium aluminum spinel particles with a particle size of 0.088-1 mm and magnesium aluminum spinel fine powder with a particle size of less than 0.088 in a mixing mill and mixing for 30 minutes to obtain a magnesium aluminum spinel raw material after mixing;

[0142] Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material and the polyvinyl alcohol aqueous solution, and perform cold isostatic pressing to obtain a magnesium-aluminum spinel refractory material embryo;

[0143] The cold isostatic pressing molding: placing the mixed material in a mold, sealing it, and moving it to a pressure chamber of an isostatic press, first increasing the pressure to 50MPa at a rate of 3MPa / s, increasing the pressure to 80MPa at a rate of 4MPa / s, increasing the pressure to 90MPa at a rate of 5MPa / s, increasing the pressure to 120MPa at a rate of 5MPa / s, and increasing the pressure to 150MPa at a rate of 6MPa / s, and maintaining the pressure for 1 minute; then reducing the pressure to 140MPa at a rate of 3MPa / s, reducing the pressure to 110MPa at a rate of 6MPa / s, reducing the pressure to 80MPa at a rate of 8MPa / s, reducing the pressure to 50MPa at a rate of 5MPa / s, and reducing the pressure to 2MPa at a rate of 5MPa / s; and finally unloading to normal pressure;

[0144] Step 3, drying the magnesium-aluminum spinel refractory material embryo at 110° C. for 24 hours, and heat treating at 1400° C. for 3 hours to obtain a magnesium-aluminum spinel refractory material matrix;

[0145] Step 4: Place the magnesium-aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution (with a concentration of 40%) and place it in a vacuum of 10 -2 MPa and the pressure is 8MPa for 4 hours; then the pyrolysis is carried out at 1000°C for 3 hours to obtain a pretreated magnesium-aluminum spinel refractory matrix;

[0146] Step 5: calcining the pretreated magnesia-alumina spinel refractory material matrix at 1600° C. for 3 hours to obtain a high-toughness magnesia-alumina spinel refractory material.

[0147] Example 9: A high-toughness magnesium-aluminum spinel refractory material and a preparation method thereof.

[0148] 1. Raw materials: Same as Example 1, except that the concentration of the lanthanum nitrate aqueous solution is 60%.

[0149] 2. Preparation method:

[0150] Step 1, placing magnesium aluminum spinel particles with a particle size of 3-5 mm, magnesium aluminum spinel particles with a particle size of 1-3 mm, magnesium aluminum spinel particles with a particle size of 0.088-1 mm and magnesium aluminum spinel fine powder with a particle size of less than 0.088 in a mixing mill and mixing for 30 minutes to obtain a magnesium aluminum spinel raw material after mixing;

[0151] Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material and the polyvinyl alcohol aqueous solution, and perform cold isostatic pressing to obtain a magnesium-aluminum spinel refractory material embryo;

[0152] The cold isostatic pressing molding: placing the mixed material in a mold, sealing it, and moving it to a pressure chamber of an isostatic press, first increasing the pressure to 50MPa at a rate of 3MPa / s, increasing the pressure to 80MPa at a rate of 4MPa / s, increasing the pressure to 90MPa at a rate of 5MPa / s, increasing the pressure to 120MPa at a rate of 5MPa / s, and increasing the pressure to 150MPa at a rate of 6MPa / s, and maintaining the pressure for 1 minute; then reducing the pressure to 140MPa at a rate of 3MPa / s, reducing the pressure to 110MPa at a rate of 6MPa / s, reducing the pressure to 80MPa at a rate of 8MPa / s, reducing the pressure to 50MPa at a rate of 5MPa / s, and reducing the pressure to 2MPa at a rate of 5MPa / s; and finally unloading to normal pressure;

[0153] Step 3, drying the magnesium-aluminum spinel refractory material embryo at 110° C. for 24 hours, and heat treating at 1400° C. for 3 hours to obtain a magnesium-aluminum spinel refractory material matrix;

[0154] Step 4: Place the magnesium aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution (concentration 60%) and place it in a vacuum of 10 -2 MPa and the pressure is 8MPa for 4 hours; then the pyrolysis is carried out at 1000°C for 3 hours to obtain a pretreated magnesium-aluminum spinel refractory matrix;

[0155] Step 5: calcining the pretreated magnesia-alumina spinel refractory material matrix at 1600° C. for 3 hours to obtain a high-toughness magnesia-alumina spinel refractory material.

[0156] Example 10: A high-toughness magnesium-aluminum spinel refractory material and a preparation method thereof

[0157] 1. Raw materials: Same as Example 1, except that the concentration of the lanthanum nitrate aqueous solution is 30%.

[0158] 2. Preparation method:

[0159] Step 1, placing magnesium aluminum spinel particles with a particle size of 3-5 mm, magnesium aluminum spinel particles with a particle size of 1-3 mm, magnesium aluminum spinel particles with a particle size of 0.088-1 mm and magnesium aluminum spinel fine powder with a particle size of less than 0.088 in a mixing mill and mixing for 30 minutes to obtain a magnesium aluminum spinel raw material after mixing;

[0160] Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material and the polyvinyl alcohol aqueous solution, and perform cold isostatic pressing to obtain a magnesium-aluminum spinel refractory material embryo;

[0161] The cold isostatic pressing molding: placing the mixed material in a mold, sealing it, and moving it to a pressure chamber of an isostatic press, first increasing the pressure to 50MPa at a rate of 3MPa / s, increasing the pressure to 80MPa at a rate of 4MPa / s, increasing the pressure to 90MPa at a rate of 5MPa / s, increasing the pressure to 120MPa at a rate of 5MPa / s, and increasing the pressure to 150MPa at a rate of 6MPa / s, and maintaining the pressure for 1 minute; then reducing the pressure to 140MPa at a rate of 3MPa / s, reducing the pressure to 110MPa at a rate of 6MPa / s, reducing the pressure to 80MPa at a rate of 8MPa / s, reducing the pressure to 50MPa at a rate of 5MPa / s, and reducing the pressure to 2MPa at a rate of 5MPa / s; and finally unloading to normal pressure;

[0162] Step 3, drying the magnesium-aluminum spinel refractory material embryo at 110° C. for 24 hours, and heat treating at 1400° C. for 3 hours to obtain a magnesium-aluminum spinel refractory material matrix;

[0163] Step 4: Place the magnesium aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution (concentration 30%) and place it in a vacuum of 10 -2 MPa and the pressure is 8MPa for 4 hours; then the pyrolysis is carried out at 1000°C for 3 hours to obtain a pretreated magnesium-aluminum spinel refractory matrix;

[0164] Step 5: calcining the pretreated magnesia-alumina spinel refractory material matrix at 1600° C. for 3 hours to obtain a high-toughness magnesia-alumina spinel refractory material.

[0165] Example 11: A high-toughness magnesia-alumina spinel refractory material and a preparation method thereof.

[0166] 1. Raw materials: Same as Example 1, except that the concentration of the lanthanum nitrate aqueous solution is 70%.

[0167] 2. Preparation method:

[0168] Step 1, placing magnesium aluminum spinel particles with a particle size of 3-5 mm, magnesium aluminum spinel particles with a particle size of 1-3 mm, magnesium aluminum spinel particles with a particle size of 0.088-1 mm and magnesium aluminum spinel fine powder with a particle size of less than 0.088 in a mixing mill and mixing for 30 minutes to obtain a magnesium aluminum spinel raw material after mixing;

[0169] Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material and the polyvinyl alcohol aqueous solution, and perform cold isostatic pressing to obtain a magnesium-aluminum spinel refractory material embryo;

[0170] The cold isostatic pressing molding: placing the mixed material in a mold, sealing it, and moving it to a pressure chamber of an isostatic press, first increasing the pressure to 50MPa at a rate of 3MPa / s, increasing the pressure to 80MPa at a rate of 4MPa / s, increasing the pressure to 90MPa at a rate of 5MPa / s, increasing the pressure to 120MPa at a rate of 5MPa / s, and increasing the pressure to 150MPa at a rate of 6MPa / s, and maintaining the pressure for 1 minute; then reducing the pressure to 140MPa at a rate of 3MPa / s, reducing the pressure to 110MPa at a rate of 6MPa / s, reducing the pressure to 80MPa at a rate of 8MPa / s, reducing the pressure to 50MPa at a rate of 5MPa / s, and reducing the pressure to 2MPa at a rate of 5MPa / s; and finally unloading to normal pressure;

[0171] Step 3, drying the magnesium-aluminum spinel refractory material embryo at 110° C. for 24 hours, and heat treating at 1400° C. for 3 hours to obtain a magnesium-aluminum spinel refractory material matrix;

[0172] Step 4: Place the magnesium-aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution (concentration of 70%) and place it in a vacuum of 10 -2 MPa and the pressure is 8MPa for 4 hours; then the pyrolysis is carried out at 1000°C for 3 hours to obtain a pretreated magnesium-aluminum spinel refractory matrix;

[0173] Step 5: calcining the pretreated magnesia-alumina spinel refractory material matrix at 1600° C. for 3 hours to obtain a high-toughness magnesia-alumina spinel refractory material.

[0174] Comparative Example 1: A magnesium-aluminum spinel refractory material

[0175] 1. Raw materials: magnesium aluminum spinel particle combination: 15 kg magnesium aluminum spinel particles with a particle size of 3-5 mm, 30 kg magnesium aluminum spinel particles with a particle size of 1-3 mm, 15 kg magnesium aluminum spinel particles with a particle size of 0.088-1 mm, and 40 kg magnesium aluminum spinel fine powder with a particle size of less than 0.088; binder, polyvinyl alcohol aqueous solution 10 kg;

[0176] 2. The preparation steps are:

[0177] Step 1, placing magnesium aluminum spinel particles with a particle size of 3-5 mm, magnesium aluminum spinel particles with a particle size of 1-3 mm, magnesium aluminum spinel particles with a particle size of 0.088-1 mm and magnesium aluminum spinel fine powder with a particle size of less than 0.088 in a mixing mill and mixing for 30 minutes to obtain a magnesium aluminum spinel raw material after mixing;

[0178] Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material and the polyvinyl alcohol aqueous solution, and perform compression molding at 150 MPa to obtain a magnesium-aluminum spinel refractory material embryo;

[0179] Step 3: Dry the magnesia-alumina spinel refractory material blank at 110° C. for 24 hours, and calcine at 1800° C. for 5 hours to obtain the magnesia-alumina spinel refractory material.

[0180] Comparative Example 2: A high-toughness magnesia-alumina spinel refractory material and a preparation method thereof.

[0181] 1. Raw materials: Same as Example 1, except that the concentration of the lanthanum nitrate aqueous solution is 25%.

[0182] 2. Preparation method:

[0183] Step 1, placing magnesium aluminum spinel particles with a particle size of 3-5 mm, magnesium aluminum spinel particles with a particle size of 1-3 mm, magnesium aluminum spinel particles with a particle size of 0.088-1 mm and magnesium aluminum spinel fine powder with a particle size of less than 0.088 in a mixing mill and mixing for 30 minutes to obtain a magnesium aluminum spinel raw material after mixing;

[0184] Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material and the polyvinyl alcohol aqueous solution, and perform cold isostatic pressing to obtain a magnesium-aluminum spinel refractory material embryo;

[0185] The cold isostatic pressing molding: placing the mixed material in a mold, sealing it, and moving it to a pressure chamber of an isostatic press, first increasing the pressure to 50MPa at a rate of 3MPa / s, increasing the pressure to 80MPa at a rate of 4MPa / s, increasing the pressure to 90MPa at a rate of 5MPa / s, increasing the pressure to 120MPa at a rate of 5MPa / s, and increasing the pressure to 150MPa at a rate of 6MPa / s, and maintaining the pressure for 1 minute; then reducing the pressure to 140MPa at a rate of 3MPa / s, reducing the pressure to 110MPa at a rate of 6MPa / s, reducing the pressure to 80MPa at a rate of 8MPa / s, reducing the pressure to 50MPa at a rate of 5MPa / s, and reducing the pressure to 2MPa at a rate of 5MPa / s; and finally unloading to normal pressure;

[0186] Step 3, drying the magnesium-aluminum spinel refractory material embryo at 110° C. for 24 hours, and heat treating at 1400° C. for 3 hours to obtain a magnesium-aluminum spinel refractory material matrix;

[0187] Step 4: Place the magnesium-aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution (concentration of 25%) and place it in a vacuum of 10 -2 MPa and the pressure is 8MPa for 4 hours; then the pyrolysis is carried out at 1000°C for 3 hours to obtain a pretreated magnesium-aluminum spinel refractory matrix;

[0188] Step 5: calcining the pretreated magnesia-alumina spinel refractory material matrix at 1600° C. for 3 hours to obtain a high-toughness magnesia-alumina spinel refractory material.

[0189] Comparative Example 3: A high-toughness magnesia-alumina spinel refractory material and a preparation method thereof.

[0190] 1. Raw materials: same as in Example 1;

[0191] 2. Preparation method: Same as Example 1, except that cold isostatic pressing is not used, specifically:

[0192] Step 1, placing magnesium aluminum spinel particles with a particle size of 3-5 mm, magnesium aluminum spinel particles with a particle size of 1-3 mm, magnesium aluminum spinel particles with a particle size of 0.088-1 mm and magnesium aluminum spinel fine powder with a particle size of less than 0.088 in a mixing mill and mixing for 30 minutes to obtain a magnesium aluminum spinel raw material after mixing;

[0193] Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material and the polyvinyl alcohol aqueous solution, and perform conventional molding at 150 MPa to obtain a magnesium-aluminum spinel refractory material embryo;

[0194] Step 3, drying the magnesium-aluminum spinel refractory material embryo at 110° C. for 24 hours, and heat treating at 1400° C. for 3 hours to obtain a magnesium-aluminum spinel refractory material matrix;

[0195] Step 4: Place the magnesium-aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution (concentration of 50%) and place it in a vacuum of 10 -2 MPa and the pressure is 8MPa for 4 hours; then the pyrolysis is carried out at 1000°C for 3 hours to obtain a pretreated magnesium-aluminum spinel refractory matrix;

[0196] Step 5: calcining the pretreated magnesia-alumina spinel refractory material matrix at 1600° C. for 3 hours to obtain a high-toughness magnesia-alumina spinel refractory material.

[0197] Comparative Example 4: A high-toughness magnesium-aluminum spinel refractory material and a preparation method thereof.

[0198] 1. Raw materials: Same as Example 1, except that the concentration of the lanthanum nitrate aqueous solution is 75%.

[0199] 2. Preparation method:

[0200] Step 1, placing magnesium aluminum spinel particles with a particle size of 3-5 mm, magnesium aluminum spinel particles with a particle size of 1-3 mm, magnesium aluminum spinel particles with a particle size of 0.088-1 mm and magnesium aluminum spinel fine powder with a particle size of less than 0.088 in a mixing mill and mixing for 30 minutes to obtain a magnesium aluminum spinel raw material after mixing;

[0201] Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material and the polyvinyl alcohol aqueous solution, and perform cold isostatic pressing to obtain a magnesium-aluminum spinel refractory material embryo;

[0202] The cold isostatic pressing molding: placing the mixed material in a mold, sealing it, and moving it to a pressure chamber of an isostatic press, first increasing the pressure to 50MPa at a rate of 3MPa / s, increasing the pressure to 80MPa at a rate of 4MPa / s, increasing the pressure to 90MPa at a rate of 5MPa / s, increasing the pressure to 120MPa at a rate of 5MPa / s, and increasing the pressure to 150MPa at a rate of 6MPa / s, and maintaining the pressure for 1 minute; then reducing the pressure to 140MPa at a rate of 3MPa / s, reducing the pressure to 110MPa at a rate of 6MPa / s, reducing the pressure to 80MPa at a rate of 8MPa / s, reducing the pressure to 50MPa at a rate of 5MPa / s, and reducing the pressure to 2MPa at a rate of 5MPa / s; and finally unloading to normal pressure;

[0203] Step 3, drying the magnesium-aluminum spinel refractory material embryo at 110° C. for 24 hours, and heat treating at 1400° C. for 3 hours to obtain a magnesium-aluminum spinel refractory material matrix;

[0204] Step 4: Place the magnesium-aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution (concentration of 25%) and place it in a vacuum of 10 -2 MPa and the pressure is 8MPa for 4 hours; then the pyrolysis is carried out at 1000°C for 3 hours to obtain a pretreated magnesium-aluminum spinel refractory matrix;

[0205] Step 5: calcining the pretreated magnesia-alumina spinel refractory material matrix at 1600° C. for 3 hours to obtain a high-toughness magnesia-alumina spinel refractory material.

[0206] Experimental Example 1: Fracture toughness investigation

[0207] 1. Sample: the heat-resistant materials provided in Examples 1 to 11 and Comparative Examples 1 to 4.

[0208] 2. Test method: Test according to national standard GB / T 23806-2009.

[0209] 3. Test results: see Table 1 and Table 2.

[0210] Table 1: Investigation results of fracture toughness and thermal shock stability

[0211]

[0212] Table 2: Fracture toughness and thermal shock stability results

[0213]

[0214] The results show that the fracture toughness of comparative example 1 (without adding lanthanum nitrate) is 5.2 MPa·m 1 / 2 The fracture toughness of comparative examples 2 and 4 is lower than 11.1 MPa·m 1 / 2 , 11.3MPa·m 1 / 2 The fracture toughness of comparative example 3 is 9.8 MPa·m 1 / 2 The fracture toughness of Examples 1 to 11 is 11.8 to 18.7 MPa·m 1 / 2 .

[0215] The results show that the fracture toughness of conventional products on the market is between 5 and 10 MPa·m 1 / 2 When the concentration of the added lanthanum nitrate aqueous solution is lower than 30% or higher than 70%, the toughness is no higher than 11.3 MPa·m 1 / 2 .

[0216] The fracture toughness of the refractory material provided by the invention is significantly increased.

[0217] Experimental Example 2: Thermal Shock Stability Investigation

[0218] During use, refractory materials are often affected by rapid changes in ambient temperature. Thermal shock stability is also known as resistance to rapid cooling and heating. The present invention also examines the thermal shock stability of refractory materials:

[0219] 1. Sample: the heat-resistant materials provided in Examples 1 to 11 and Comparative Examples 1 to 4.

[0220] 2. Test method: According to the water quenching method (small test) in the national standard GB / T 30873-2014.

[0221] 3. Test results: see Table 1 and Table 2

[0222] The experimental results show that the thermal shock stability of comparative example 1 (without lanthanum nitrate) is 18 times, the thermal shock stability of comparative examples 2 and 4 (lanthanum nitrate concentration of 25% and 75%) is 39 times and 34 times respectively, the thermal shock stability of comparative example 3 (without cold isostatic pressing) is 22 times, and the thermal shock stability of embodiments 1 to 11 reaches 42 to 60 times.

[0223] Conclusion: The thermal shock stability of conventional products on the market is about 10 to 30 times. When the concentration of the added lanthanum nitrate aqueous solution is lower than 30% or higher than 70%, the thermal shock stability also increases slightly, which is significantly inferior to other proportions.

[0224] The results show that the method provided by the present invention is better.

[0225] The results of Experimental Examples 1 and 2 show that the fracture toughness and thermal shock stability of the high-toughness magnesia-alumina spinel refractory material provided by the present invention are better than those of other products.

[0226] Experimental Example 3: Microscopic Observation

[0227] 1. Samples: Comparative Example 1 (without addition of lanthanum nitrate), Comparative Example 3 (without cold isostatic pressing), and Example 1.

[0228] 2. Observation method: The prepared magnesium-aluminum spinel material was observed by a scanning electron microscope (SEM) at a magnification of 10,000 times.

[0229] 3. Experimental results are shown in Figure

[0230] Figure 1 This is a picture of comparative example 1. The microstructure of the sample without lanthanum nitrate addition shows that the grains of magnesium aluminum spinel are of different sizes and there are a lot of pore structures;

[0231] Figure 2 This is a picture of Comparative Example 3, where the microstructure of the sample that was not cold isostatically pressed shows that the lanthanum hexaaluminate flake structure is unevenly distributed;

[0232] Figure 3 This is a picture of Example 1. The microstructure shows that the magnesium aluminum spinel grains and the lanthanum hexaaluminate flaky structure are evenly distributed and have good bonding.

[0233] The results show that the refractory material provided by the present invention has uniform phase structure distribution and good bonding properties.

[0234] Experimental Example 4: High temperature stability study

[0235] 1. Samples: Example 1, Comparative Example 1 (no lanthanum nitrate added).

[0236] 2. Observation method: X-ray diffractometer (Philips XPert PRO MPD, PANalytical, Netherlands) was used to detect the phase composition of the material.

[0237] 3. Experimental results:

[0238] Figure 4 The XRD diagrams of the magnesia-alumina spinel refractory material with the addition of lanthanum nitrate aqueous solution (concentration of 50%) (Example 1) and without the addition of lanthanum nitrate (Comparative Example 1).

[0239] It can be seen from the figure that the low melting point phase CaMgSiO 4 The content is high, while the low melting point phase CaMgSiO in the modified magnesium aluminum spinel with rare earth metal ions added 4 The content of rare earth metal ions La 3 + Will react with the low melting point phase CaMgSiO 4 Instead, it should be converted to Ca which has a higher melting point. 2 La 8 (SiO 4 ) 6 O 2 phase, which is beneficial to improve the high-temperature structural stability of the modified magnesia-alumina spinel.

[0240] Results show that the lanthanum nitrate introduced in the present invention decomposes rare earth lanthanum ions during the high-temperature cracking process, which can effectively absorb impurities such as calcium and silicon in the raw materials and convert them into a high-melting-point rare earth calcium silicate composite phase, greatly improving the high-temperature structural stability of the magnesium-aluminum spinel refractory material.

[0241] Although the present invention has been described in detail above by means of general description, specific implementation methods and tests, it is obvious to those skilled in the art that some modifications or improvements may be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A high-toughness magnesium-aluminum spinel refractory material, characterized in that: The raw materials are composed of the following materials in parts by weight: 10-20 parts of magnesium aluminum spinel particles with a particle size of 3-5 mm, 20-40 parts of magnesium aluminum spinel particles with a particle size of 1-3 mm, 10-20 parts of magnesium aluminum spinel particles with a particle size of 0.088-1 mm and 30-50 parts of magnesium aluminum spinel fine powder with a particle size of less than 0.088, and 5-10 parts of a binder. The above materials are mixed and formed by cold isostatic pressing, and then the formed object is immersed in a lanthanum nitrate aqueous solution with a concentration of 40-60%, and the binder is a polyvinyl alcohol aqueous solution with a concentration of 10%; It is prepared by the following method: Step 1: Mix and grind 15 wt% of magnesia-alumina spinel particles with a particle size of 3-5 mm, 30 wt% of magnesia-alumina spinel particles with a particle size of 1-3 mm, 15 wt% of magnesia-alumina spinel particles with a particle size of 0.088-1 mm, and 40 wt% of magnesia-alumina spinel fine powder with a particle size of less than 0.088 for 30 minutes to obtain a mixed magnesia-alumina spinel raw material; Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material with a 5-10wt% polyvinyl alcohol aqueous solution, and perform cold isostatic pressing to obtain a magnesium-aluminum spinel refractory material embryo; The cold isostatic pressing molding comprises placing the mixed material in a mold, sealing the mold, and moving the mold into a pressure chamber of an isostatic press. The pressure is first increased to 30-50 MPa at a rate of 0.1-4 MPa / s, then to 60-80 MPa at a rate of 0.1-5 MPa / s, then to 90-110 MPa at a rate of 0.1-10 MPa / s, then to 120-140 MPa at a rate of 0.1-6 MPa / s, then to 120-140 MPa at a rate of 0.1-8 MPa / s. To 150~200MPa, maintain the pressure for 1~5min; then reduce the pressure to 120~140MPa at a rate of 0.1~5MPa / s, reduce the pressure to 90~110MPa at a rate of 0.1~6MPa / s, reduce the pressure to 60~80MPa at a rate of 0.1~8MPa / s, reduce the pressure to 30~50MPa at a rate of 0.1~5MPa / s, and reduce the pressure to 2MPa at a rate of 0.1~5MPa / s; finally unload to normal pressure; Step 3, drying the magnesia-alumina spinel refractory material embryo at 110-120° C. for 12-36 hours, and heat treating at 1400-1600° C. for 2-5 hours to obtain a magnesia-alumina spinel refractory material matrix; Step 4: Place the magnesium aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution and place it in a vacuum of 10 -3 ~10 - 2 MPa and a pressure of 5 to 8 MPa for 4 to 8 hours; then high-temperature cracking at 800 to 1200°C for 1 to 3 hours to obtain a pretreated magnesium-aluminum spinel refractory material matrix; Step 5, calcining the pretreated magnesium-aluminum spinel refractory material matrix at 1600-1800° C. for 3-5 hours to obtain a high-toughness magnesium-aluminum spinel refractory material; The chemical composition of the magnesium-aluminum spinel particles is: MgO=10~15wt%, Al2O3=85~90wt%, CaO≤0.7wt%, SiO2≤0.6wt%, Fe2O3≤0.5wt%.

2. The high-toughness magnesia-alumina spinel refractory material according to claim 1, characterized in that: The concentration of the lanthanum nitrate aqueous solution is 40-55%.

3. The high-toughness magnesia-alumina spinel refractory material according to claim 1, characterized in that: The concentration of the lanthanum nitrate aqueous solution is 50-55%.

4. The high-toughness magnesia-alumina spinel refractory material according to claim 1, characterized in that: 12-18 parts of magnesia-alumina spinel particles with a particle size of 3-5 mm, 25-35 parts of magnesia-alumina spinel particles with a particle size of 1-3 mm, 12-18 parts of magnesia-alumina spinel particles with a particle size of 0.088-1 mm and 35-45 parts of magnesia-alumina spinel fine powder with a particle size of less than 0.088, and 5-10 parts of a binder.

5. The high-toughness magnesia-alumina spinel refractory material according to claim 1, characterized in that: The raw materials of the high-toughness magnesia-alumina spinel refractory material are the following materials in parts by weight: 15 parts of magnesia-alumina spinel particles with a particle size of 3-5 mm, 30 parts of magnesia-alumina spinel particles with a particle size of 1-3 mm, 15 parts of magnesia-alumina spinel particles with a particle size of 0.088-1 mm and 40 parts of magnesia-alumina spinel fine powder with a particle size of less than 0.088, and 5-10 parts of a binder.

6. A method for preparing the high-toughness magnesia-alumina spinel refractory material according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: Step 1: Mix and grind 15 wt% of magnesia-alumina spinel particles with a particle size of 3-5 mm, 30 wt% of magnesia-alumina spinel particles with a particle size of 1-3 mm, 15 wt% of magnesia-alumina spinel particles with a particle size of 0.088-1 mm, and 40 wt% of magnesia-alumina spinel fine powder with a particle size of less than 0.088 for 30 minutes to obtain a mixed magnesia-alumina spinel raw material; Step 2: Mix the mixed and milled magnesium-aluminum spinel raw material with a 5-10wt% polyvinyl alcohol aqueous solution, and perform cold isostatic pressing to obtain a magnesium-aluminum spinel refractory material embryo; The cold isostatic pressing molding comprises placing the mixed material in a mold, sealing the mold, and moving the mold into a pressure chamber of an isostatic press. The pressure is first increased to 30-50 MPa at a rate of 0.1-4 MPa / s, then to 60-80 MPa at a rate of 0.1-5 MPa / s, then to 90-110 MPa at a rate of 0.1-10 MPa / s, then to 120-140 MPa at a rate of 0.1-6 MPa / s, then to 120-140 MPa at a rate of 0.1-8 MPa / s. To 150~200MPa, maintain the pressure for 1~5min; then reduce the pressure to 120~140MPa at a rate of 0.1~5MPa / s, reduce the pressure to 90~110MPa at a rate of 0.1~6MPa / s, reduce the pressure to 60~80MPa at a rate of 0.1~8MPa / s, reduce the pressure to 30~50MPa at a rate of 0.1~5MPa / s, and reduce the pressure to 2MPa at a rate of 0.1~5MPa / s; finally unload to normal pressure; Step 3, drying the magnesia-alumina spinel refractory material embryo at 110-120° C. for 12-36 hours, and heat treating at 1400-1600° C. for 2-5 hours to obtain a magnesia-alumina spinel refractory material matrix; Step 4: Place the magnesium aluminum spinel refractory material matrix in a lanthanum nitrate aqueous solution and place it in a vacuum of 10 -3 ~10 - 2 MPa and a pressure of 5 to 8 MPa for 4 to 8 hours; then high-temperature cracking at 800 to 1200°C for 1 to 3 hours to obtain a pretreated magnesium-aluminum spinel refractory material matrix; Step 5: calcining the pretreated magnesium-aluminum spinel refractory material matrix at 1600-1800° C. for 3-5 hours to obtain a high-toughness magnesium-aluminum spinel refractory material.

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