Preparation process of high-strength compact sintered refractory material

Abstract

The invention relates to a preparation process of a high-strength compact sintered refractory material, which comprises the following steps: mixing and grinding raw materials, adding predetermined parts by weight of pulverized coal, uniformly mixing, sintering in a rotary kiln, gradually heating and sintering, carrying out ball milling and mixing on the pre-sintered material powder in absolute ethyl alcohol, drying, and carrying out dry pressing molding under predetermined pressure to obtain the high-strength compact sintered refractory material. Spraying a sodium carbonate aqueous solution to prepare a refractory material green body, sintering the green body at a predetermined temperature, roasting for several hours at the predetermined temperature, and naturally cooling to room temperature to prepare the refractory material. By adjusting the formula and the preparation process, the mechanical property and the thermal shock resistance of the refractory material are improved, the problem that cracks are generated in a quick-cooling and quick-heating environment is solved, the service life is prolonged, and the production requirement of a device is met.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of refractory materials, in particular to a preparation process of high-strength dense sintered refractory materials. BACKGROUND

[0002] In recent years, with the rapid development of smelting technology and steel technology, refractory materials have also achieved a series of major changes, and are gradually changing from the original product group relying on natural raw materials and mass production to the precise and high-grade product series taking multi-variety, small-batch, artificial raw materials, development and design as principles, that is, from the classical refractory materials to diversified new refractory materials. The high-temperature structural refractory material required by the needle coke calcination device rotary kiln equipment needs to have excellent comprehensive performance, including mechanical properties, thermal shock resistance, oxidation resistance and machinability. The traditional refractory material has the problem of poor mechanical toughness, and cracks are easily generated in the rapid cooling and heating environment, affecting the service life. SUMMARY

[0003] An advantage of the application is to provide a preparation process of high-strength dense sintered refractory materials, which improves the mechanical properties and thermal shock resistance of the refractory materials by adjusting the formula and preparation process, solves the problem of cracks in the rapid cooling and heating environment, prolongs the service life, and meets the production requirements of the device.

[0004] To achieve at least one of the above advantages of the application, the application provides a preparation process of high-strength dense sintered refractory materials. The raw materials are mixed and ground, coal powder with a predetermined weight fraction is added, the mixture is uniformly mixed and then put into a rotary kiln for sintering, the sintering is gradually heated, the pre-sintered material powder is mixed by ball milling in anhydrous ethanol and then dried, dry pressing is performed under a predetermined pressure, a sodium carbonate aqueous solution is sprayed to obtain a green body of the refractory material, the green body is sintered at a predetermined temperature, and then baked at a predetermined temperature for several hours, and then naturally cooled to room temperature to obtain the refractory material.

[0005] According to an embodiment of the application, the raw materials include alumina, chromium oxide, silicon oxide, calcium oxide, magnesium oxide, titanium oxide, gadolinium oxide, niobium pentoxide and modified zirconia fiber.

[0006] According to an embodiment of the application, the mass fraction of alumina is 60-80%, the mass fraction of chromium oxide is 5-10%, the mass fraction of silicon oxide is 3-8%, the mass fraction of calcium oxide is 1-3%, the mass fraction of magnesium oxide is 1-3%, the mass fraction of titanium oxide is 1-5%, the mass fraction of gadolinium oxide is 0.5-2%, and the mass fraction of niobium pentoxide is 0.5-2%.

[0007] According to an embodiment of the application, the mass fraction of modified zirconia fiber is 3-8%.

[0008] According to one embodiment of the present invention, the pulverized coal is 6-8% by weight, the sintering temperature is 900-1000°C, and the sintering time is 2-3 hours.

[0009] According to one embodiment of the present invention, the pre-calcined material powder is ball-milled in anhydrous ethanol for 3 to 5 hours.

[0010] According to one embodiment of the present invention, the predetermined pressure for dry pressing is 100-150 MPa, and the concentration of the sodium carbonate aqueous solution is 5-10% (w / w).

[0011] According to one embodiment of the present invention, the sintering temperature of the green body is 1200-1400°C, the sintering time of the green body is 3-5 hours, the baking temperature of the green body is 2200-2400°C, and the baking time of the green body is 8-10 hours. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of this invention clearer, this invention will be described in more detail.

[0013] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0014] This invention provides a process for preparing high-strength, dense, sintered refractory materials. The raw materials include alumina, chromium oxide, silicon oxide, calcium oxide, magnesium oxide, titanium oxide, gadolinium oxide, niobium pentoxide, and modified zirconium oxide fibers. Alumina (Al₂O₃) is the main component, providing high hardness, wear resistance, and chemical stability. Chromium oxide (Cr₂O₃) enhances corrosion resistance and high-temperature stability, and improves mechanical properties. Silicon oxide (SiO₂) acts as a stabilizer, regulating the sintering temperature and improving thermal shock resistance. Calcium oxide (CaO) promotes sintering, lowers the sintering temperature, and improves densification. Magnesium oxide (MgO) improves thermal stability and creep resistance. Titanium oxide (TiO₂) enhances mechanical properties and regulates grain growth. Gadolinium oxide (Gd₂O₃) improves high-temperature performance and may be used in special functional ceramics (such as electronic materials). Niobium pentoxide (Nb₂O₅) enhances thermal shock resistance and mechanical strength and may be used in high-toughness materials. Modified zirconia fibers (such as fibers containing stabilizer ZrO2) are used to enhance the toughness and fracture resistance of materials and improve the microstructure. After crushing, they are subjected to magnetic separation to remove ferromagnetic substances.

[0015] Example 1: (1) Mix and grind the raw materials, add 10 kg of coal powder (6% of the weight of the raw materials), mix evenly, and then put it into a rotary kiln for sintering. Gradually raise the temperature to 900℃ and sinter for 2 hours.

[0016] (2) The pre-calcined material powder was ball-milled in anhydrous ethanol for 3 hours and then dried.

[0017] (3) The refractory green body was prepared by dry pressing under 110 MPa pressure and spraying with 5% (w / w) sodium carbonate aqueous solution.

[0018] (4) The green blank is sintered at 1200℃ for 3 hours, then baked at 2200℃ for 8 hours, and naturally cooled to room temperature to obtain refractory material.

[0019] Composition of raw materials: The mass fraction of alumina is 63%, chromium oxide is 6%, silicon oxide is 5%, calcium oxide is 2%, magnesium oxide is 1%, titanium oxide is 2%, gadolinium oxide is 1%, niobium pentoxide is 1.5%, and modified zirconium oxide fiber is 4%.

[0020] Example 2: (1) Mix and grind the raw materials, add 10 kg of coal powder (6% of the weight of the raw materials), mix evenly, and then put it into a rotary kiln for sintering. Gradually raise the temperature to 950℃ and sinter for 2 hours.

[0021] (2) The pre-calcined material powder was ball-milled in anhydrous ethanol for 3 hours and then dried.

[0022] (3) The refractory green body was prepared by dry pressing under 130 MPa pressure and spraying with 6% (w / w) sodium carbonate aqueous solution.

[0023] (4) The green blank is sintered at 1300℃ for 5 hours, then baked at 2300℃ for 8 hours, and naturally cooled to room temperature to obtain refractory material.

[0024] Composition of raw materials: The mass fraction of alumina is 66%, the mass fraction of chromium oxide is 5%, the mass fraction of silicon oxide is 4%, the mass fraction of calcium oxide is 1%, the mass fraction of magnesium oxide is 1%, the mass fraction of titanium oxide is 2%, the mass fraction of gadolinium oxide is 2%, the mass fraction of niobium pentoxide is 1%, and the mass fraction of modified zirconium oxide fiber is 4%.

[0025] Example 3: (1) Mix and grind the raw materials, add 10 kg of coal powder (6% of the weight of the raw materials), mix evenly, and then put it into a rotary kiln for sintering. Gradually raise the temperature to 950℃ and sinter for 3 hours.

[0026] (2) The pre-calcined material powder was ball-milled in anhydrous ethanol for 5 hours and then dried.

[0027] (3) Molding and pressing: Dry pressing is performed under a pressure of 120MPa, and a 6% (w / w) sodium carbonate aqueous solution is sprayed to obtain refractory green blanks.

[0028] (4) The green blank is sintered at 1300℃ for 3 hours, then baked at 2300℃ for 8 hours, and naturally cooled to room temperature to obtain refractory material.

[0029] Composition of raw materials: The mass fraction of alumina is 69%, the mass fraction of chromium oxide is 7%, the mass fraction of silicon oxide is 5%, the mass fraction of calcium oxide is 2%, the mass fraction of magnesium oxide is 2%, the mass fraction of titanium oxide is 3%, the mass fraction of gadolinium oxide is 1%, the mass fraction of niobium pentoxide is 1%, and the mass fraction of modified zirconium oxide fiber is 6%.

[0030] Example 4: (1) Mix and grind the raw materials, add 10 kg of coal powder (8% of the weight of the raw materials), mix evenly, and then put it into a rotary kiln for sintering. Gradually raise the temperature to 950℃ and sinter for 3 hours.

[0031] (2) The pre-calcined material powder was ball-milled in anhydrous ethanol for 5 hours and then dried.

[0032] (3) The refractory green body was prepared by dry pressing under 120 MPa pressure and spraying with 8% (w / w) sodium carbonate aqueous solution.

[0033] (4) The green blank is sintered at 1300℃ for 5 hours, then baked at 2300℃ for 10 hours, and naturally cooled to room temperature to obtain refractory material.

[0034] Composition of raw materials: The mass fraction of alumina is 75%, the mass fraction of chromium oxide is 8%, the mass fraction of silicon oxide is 5%, the mass fraction of calcium oxide is 2%, the mass fraction of magnesium oxide is 3%, the mass fraction of titanium oxide is 4%, the mass fraction of gadolinium oxide is 1%, the mass fraction of niobium pentoxide is 1.5%, and the mass fraction of modified zirconium oxide fiber is 4%.

[0035] Example 5: (1) Mix and grind the raw materials, add 10 kg of coal powder (8% of the weight of the raw materials), mix evenly, and then put it into a rotary kiln for sintering. Gradually raise the temperature to 1000℃ and sinter for 3 hours.

[0036] (2) The pre-calcined material powder was ball-milled in anhydrous ethanol for 5 hours and then dried.

[0037] (3) The refractory green body was prepared by dry pressing under a pressure of 150 MPa and spraying with a 10% (w / w) sodium carbonate aqueous solution.

[0038] (4) The green blank is sintered at 1400℃ for 5 hours, then baked at 2400℃ for 10 hours, and naturally cooled to room temperature to obtain refractory material.

[0039] Composition of raw materials: The mass fraction of alumina is 72%, the mass fraction of chromium oxide is 7%, the mass fraction of silicon oxide is 4%, the mass fraction of calcium oxide is 3%, the mass fraction of magnesium oxide is 2%, the mass fraction of titanium oxide is 4%, the mass fraction of gadolinium oxide is 2%, the mass fraction of niobium pentoxide is 1.5%, and the mass fraction of modified zirconium oxide fiber is 6%.

[0040] Example 6: (1) Mix and grind the raw materials, add 10 kg of coal powder (8% of the weight of the raw materials), mix evenly, and then put it into a rotary kiln for sintering. Gradually raise the temperature to 1000℃ and sinter for 2 hours.

[0041] (2) The pre-calcined material powder was ball-milled in anhydrous ethanol for 3 hours and then dried.

[0042] (3) The refractory green body was prepared by dry pressing under a pressure of 150 MPa and spraying with a 10% (w / w) sodium carbonate aqueous solution.

[0043] (4) The green blank is sintered at 1400℃ for 4 hours, then baked at 2400℃ for 9 hours, and naturally cooled to room temperature to obtain refractory material.

[0044] Composition of raw materials: The mass fraction of alumina is 71%, the mass fraction of chromium oxide is 8%, the mass fraction of silicon oxide is 6%, the mass fraction of calcium oxide is 1%, the mass fraction of magnesium oxide is 2%, the mass fraction of titanium oxide is 3%, the mass fraction of gadolinium oxide is 1%, the mass fraction of niobium pentoxide is 2%, and the mass fraction of modified zirconium oxide fiber is 5%.

[0045] For example, to demonstrate the advantages of the process, the sodium carbonate solution is replaced with a sodium hydroxide solution.

[0046] Comparative Example 1: (1) Mix and grind the raw materials, add 10 kg of coal powder (6% of the weight of the raw materials), mix evenly, and then put it into a rotary kiln for sintering. Gradually raise the temperature to 900℃ and sinter for 2 hours.

[0047] (2) The pre-calcined material powder was ball-milled in anhydrous ethanol for 3 hours and then dried.

[0048] (3) The refractory green body was prepared by dry pressing under 110 MPa pressure and spraying with 5% (w / w) sodium hydroxide solution.

[0049] (4) The green blank is sintered at 1200℃ for 3 hours, then baked at 2200℃ for 8 hours, and naturally cooled to room temperature to obtain refractory material.

[0050] Composition of raw materials: The mass fraction of alumina is 63%, chromium oxide is 6%, silicon oxide is 5%, calcium oxide is 2%, magnesium oxide is 1%, titanium oxide is 2%, gadolinium oxide is 1%, niobium pentoxide is 1.5%, and modified zirconium oxide fiber is 4%.

[0051] Comparative Example 2: (1) Mix and grind the raw materials, add 10 kg of coal powder (6% of the weight of the raw materials), mix evenly, and then put it into a rotary kiln for sintering. Gradually raise the temperature to 950℃ and sinter for 2 hours.

[0052] (2) The pre-calcined material powder was ball-milled in anhydrous ethanol for 3 hours and then dried.

[0053] (3) The refractory green body was prepared by dry pressing under 130 MPa pressure and spraying with 6% (w / w) sodium hydroxide solution.

[0054] (4) The green blank is sintered at 1300℃ for 5 hours, then baked at 2300℃ for 8 hours, and naturally cooled to room temperature to obtain refractory material.

[0055] Composition of raw materials: The mass fraction of alumina is 66%, the mass fraction of chromium oxide is 5%, the mass fraction of silicon oxide is 4%, the mass fraction of calcium oxide is 1%, the mass fraction of magnesium oxide is 1%, the mass fraction of titanium oxide is 2%, the mass fraction of gadolinium oxide is 2%, the mass fraction of niobium pentoxide is 1%, and the mass fraction of modified zirconium oxide fiber is 4%.

[0056] Comparative Example 3: (1) Mix and grind the raw materials, add 10 kg of coal powder (6% of the weight of the raw materials), mix evenly, and then put it into a rotary kiln for sintering. Gradually raise the temperature to 950℃ and sinter for 3 hours.

[0057] (2) The pre-calcined material powder was ball-milled in anhydrous ethanol for 5 hours and then dried.

[0058] (3) Molding and pressing: Dry pressing is performed under a pressure of 120MPa, and a 6% (w / w) sodium hydroxide solution is sprayed to obtain refractory green blanks.

[0059] (4) The green blank is sintered at 1300℃ for 3 hours, then baked at 2300℃ for 8 hours, and naturally cooled to room temperature to obtain refractory material.

[0060] Composition of raw materials: The mass fraction of alumina is 69%, the mass fraction of chromium oxide is 7%, the mass fraction of silicon oxide is 5%, the mass fraction of calcium oxide is 2%, the mass fraction of magnesium oxide is 2%, the mass fraction of titanium oxide is 3%, the mass fraction of gadolinium oxide is 1%, the mass fraction of niobium pentoxide is 1%, and the mass fraction of modified zirconium oxide fiber is 6%.

[0061] Comparative Example 4: (1) Mix and grind the raw materials, add 10 kg of coal powder (8% of the weight of the raw materials), mix evenly, and then put it into a rotary kiln for sintering. Gradually raise the temperature to 950℃ and sinter for 3 hours.

[0062] (2) The pre-calcined material powder was ball-milled in anhydrous ethanol for 5 hours and then dried.

[0063] (3) The refractory green body was prepared by dry pressing under 120 MPa pressure and spraying with 8% (w / w) sodium hydroxide solution.

[0064] (4) The green blank is sintered at 1300℃ for 5 hours, then baked at 2300℃ for 10 hours, and naturally cooled to room temperature to obtain refractory material.

[0065] Composition of raw materials: The mass fraction of alumina is 75%, the mass fraction of chromium oxide is 8%, the mass fraction of silicon oxide is 5%, the mass fraction of calcium oxide is 2%, the mass fraction of magnesium oxide is 3%, the mass fraction of titanium oxide is 4%, the mass fraction of gadolinium oxide is 1%, the mass fraction of niobium pentoxide is 1.5%, and the mass fraction of modified zirconium oxide fiber is 4%.

[0066] Comparative Example 5: (1) Mix and grind the raw materials, add 10 kg of coal powder (8% of the weight of the raw materials), mix evenly, and then put it into a rotary kiln for sintering. Gradually raise the temperature to 1000℃ and sinter for 3 hours.

[0067] (2) The pre-calcined material powder was ball-milled in anhydrous ethanol for 5 hours and then dried.

[0068] (3) The refractory green body was prepared by dry pressing under a pressure of 150 MPa and spraying with a 10% (w / w) sodium hydroxide solution.

[0069] (4) The green blank is sintered at 1400℃ for 5 hours, then baked at 2400℃ for 10 hours, and naturally cooled to room temperature to obtain refractory material.

[0070] Composition of raw materials: The mass fraction of alumina is 72%, the mass fraction of chromium oxide is 7%, the mass fraction of silicon oxide is 4%, the mass fraction of calcium oxide is 3%, the mass fraction of magnesium oxide is 2%, the mass fraction of titanium oxide is 4%, the mass fraction of gadolinium oxide is 2%, the mass fraction of niobium pentoxide is 1.5%, and the mass fraction of modified zirconium oxide fiber is 6%.

[0071] Comparative Example 6: (1) Mix and grind the raw materials, add 10 kg of coal powder (8% of the weight of the raw materials), mix evenly, and then put it into a rotary kiln for sintering. Gradually raise the temperature to 1000℃ and sinter for 2 hours.

[0072] (2) The pre-calcined material powder was ball-milled in anhydrous ethanol for 3 hours and then dried.

[0073] (3) The refractory green body was prepared by dry pressing under a pressure of 150 MPa and spraying with a 10% (w / w) sodium hydroxide solution.

[0074] (4) The green blank is sintered at 1400℃ for 4 hours, then baked at 2400℃ for 9 hours, and naturally cooled to room temperature to obtain refractory material.

[0075] Composition of raw materials: The mass fraction of alumina is 71%, the mass fraction of chromium oxide is 8%, the mass fraction of silicon oxide is 6%, the mass fraction of calcium oxide is 1%, the mass fraction of magnesium oxide is 2%, the mass fraction of titanium oxide is 3%, the mass fraction of gadolinium oxide is 1%, the mass fraction of niobium pentoxide is 2%, and the mass fraction of modified zirconium oxide fiber is 5%.

[0076] Thermogravimetric properties were tested using a TG-DSC thermogravimetric analyzer at an air temperature of 100-1000℃ and a heating rate of 10℃ / min. The heat resistance was measured by the weight loss rate. The test standard was based on "Test Method for Weight Loss and Residual Amount of Thermogravimetric Analyzer" (GB / T 27761-2011). The test results are shown in Table 1.

[0077] Table 1 Results of thermogravimetric performance tests

[0078] (1) Examples 1-6 show a slight increase in thermogravimetric properties with increasing temperature, but there is no significant difference, and the heat resistance is good.

[0079] (2) Comparative Examples 1-6 showed a significant improvement in thermal weight loss performance with increasing temperature, but poor heat resistance.

[0080] (3) As seen in Example 1 and Comparative Example 1, the thermal weight loss performance in the low temperature range is basically the same, but as the temperature increases, the thermal weight loss performance is significantly different. The thermal weight loss of the comparative example finally reached 55%, which is a very high weight loss ratio.

[0081] In summary, the refractory materials prepared using the process described in this application exhibit excellent heat resistance and can meet the production requirements under high-temperature environments.

Claims

1. A process for preparing high-strength, dense, sintered refractory materials, characterized in that: The raw materials are mixed and ground, and a predetermined amount of coal powder is added. After mixing evenly, the mixture is placed in a rotary kiln for sintering. The temperature is gradually increased during sintering. The pre-fired material powder is ball-milled and mixed in anhydrous ethanol and then dried. It is then dry-pressed under a predetermined pressure and sprayed with sodium carbonate aqueous solution to obtain refractory green blanks. The green blanks are sintered at a predetermined temperature and then baked at a predetermined temperature for several hours. After natural cooling to room temperature, the refractory material is obtained.

2. The preparation process of high-strength dense sintered refractory material according to claim 1, characterized in that: The raw materials include alumina, chromium oxide, silicon oxide, calcium oxide, magnesium oxide, titanium oxide, gadolinium oxide, niobium pentoxide, and modified zirconium oxide fiber.

3. The preparation process of high-strength dense sintered refractory material according to claim 2, characterized in that: The mass fraction of aluminum oxide is 60-80%, the mass fraction of chromium oxide is 5-10%, the mass fraction of silicon oxide is 3-8%, the mass fraction of calcium oxide is 1-3%, the mass fraction of magnesium oxide is 1-3%, the mass fraction of titanium oxide is 1-5%, the mass fraction of gadolinium oxide is 0.5-2%, and the mass fraction of niobium pentoxide is 0.5-2%.

4. The preparation process of high-strength dense sintered refractory material according to claim 2, characterized in that: The mass fraction of modified zirconia fiber is 3-8%.

5. The preparation process of high-strength dense sintered refractory material according to claim 1, characterized in that: The pulverized coal has a weight percentage of 6-8%, a sintering temperature of 900-1000℃, and a sintering time of 2-3 hours.

6. The preparation process of high-strength dense sintered refractory material according to claim 1, characterized in that: The pre-calcined material powder is ball-milled in anhydrous ethanol for 3 to 5 hours.

7. The preparation process of high-strength dense sintered refractory material according to claim 1, characterized in that: The predetermined pressure for dry pressing is 100-150 MPa, and the concentration of sodium carbonate aqueous solution is 5-10% (w / w).

8. The preparation process of high-strength dense sintered refractory material according to claim 1, characterized in that: The sintering temperature of the green body is 1200-1400℃, the sintering time is 3-5 hours, the baking temperature of the green body is 2200-2400℃, and the baking time is 8-10 hours.

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