Method for one-step synthesis of aluminum titanate ceramic riser

Abstract

The application belongs to the technical field of aluminum titanate liquid lifting pipe and specifically relates to a method for synthesizing an aluminum titanate ceramic liquid lifting pipe once. The application comprises the following steps: (1) mixing raw materials, ball milling, drying, sieving and standing and cooling to obtain a powder; (2) sieving the powder and performing cold isostatic pressing to obtain a green body; and (3) processing the green body and sintering to form a product. The raw materials comprise aluminum oxide, titanium dioxide, zinc oxide and strontium carbonate. The application has higher production efficiency, saves energy and is more conducive to large-scale industrial production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aluminum titanate riser tube and particularly relates to a method for synthesizing an aluminum titanate ceramic riser tube in one step. BACKGROUND

[0002] Aluminum titanate is widely used in various industries such as metallurgy, chemical industry, environmental protection and the like due to its unique low thermal expansion performance. As one of the best in low thermal expansion performance, aluminum titanate has various applications in automobiles, chemical industry, glass, metallurgy and the like. For example, riser tube, temperature measuring thermocouple protective sleeve, crucible, filter and the like. The riser tube is a kind of accessory for low pressure casting, which mainly functions as a flow guide and a feeding channel. It is connected with the crucible cover in a detachable manner to form a sealed container for pressure bearing. The material used for the riser tube must have high temperature resistance, thermal shock resistance, aluminum liquid corrosion resistance and good air tightness, and must have long-term thermal shock fatigue resistance; aluminum titanate has high melting point, good thermal shock resistance, low thermal expansion coefficient and non-wetting property with non-ferrous metals, and is a very good riser tube material.

[0003] The common synthesis method of aluminum titanate is to react and sinter titanium dioxide with aluminum oxide, magnesium oxide and other oxides. The main component of mullite is aluminum oxide and silicon oxide, which has good high temperature resistance, low impurity content, very low iron and alkali metal oxide content, high refractoriness, low thermal melting and low thermal conductivity, and can be used as a raw material of aluminum titanate. Since the Al 3+ ion in aluminum titanate has weak binding capacity and is easy to deform the crystal lattice under heat, leading to decomposition. If you want to stabilize it, you need to add additives to distort the crystal form of aluminum titanate, so that it is stable and not easy to decompose. At present, the most commonly used additives are magnesium oxide, zirconium oxide and the like. In addition, the poor mechanical properties of aluminum titanate are a big weakness. In order to solve these problems, other oxides need to be added as additives to improve its performance. The traditional synthesis method of aluminum titanate is mostly secondary synthesis or multiple synthesis. The first step needs to pretreat and sinter the raw materials, the main purpose of which is to increase the crystal lattice distortion and the reactivity of the raw materials through pretreatment, so as to reduce the synthesis temperature, but this increases the energy consumption and the complexity of the process. SUMMARY

[0004] To solve the above technical problems, the application provides a method for synthesizing an aluminum titanate ceramic riser tube in one step, which has higher production efficiency, saves energy and is more conducive to large-scale industrial production.

[0005] The method for synthesizing an aluminum titanate ceramic riser tube in one step provided by the application comprises the following steps:

[0006] (1) mixing raw materials, ball milling, drying and sieving, and then standing and cooling to obtain a powder;

[0007] (2) sieving the powder and then cold isostatic pressing to form a green body;

[0008] (3) processing the green body and then sintering to form;

[0009] The raw materials include alumina, titanium dioxide, zinc oxide and strontium carbonate.

[0010] Preferably, the mass percentage of the alumina, titanium dioxide, zinc oxide and strontium carbonate in the raw materials is respectively:

[0011] Alumina 40%-48%;

[0012] Titanium dioxide 44%-52%;

[0013] Zinc oxide 1%-4%;

[0014] Strontium carbonate 1%-4%.

[0015] Preferably, the ball milling is to a particle size D50=2-2.3 μm.

[0016] Preferably, the drying is to a volatile matter content of ≤0.5%.

[0017] Preferably, the standing cooling time is ≥24 h.

[0018] Preferably, in the step (1) and the step (2), the sieving is sieving 80 # mesh.

[0019] Preferably, the specific process of the step (2) is: after sieving the powder, the powder is loaded into a shaped rubber sleeve, a cold isostatic pressing device is used to slowly pressurize, the pressure is maintained for 5 min or more, and then the pressure is slowly released to obtain a green body.

[0020] Preferably, the pressure is 100-150 MPa.

[0021] Preferably, the sintering temperature is 1500-1600 ℃.

[0022] The present application selects strontium carbonate and zinc oxide as additives to modify the aluminum titanate: the strontium oxide and zinc oxide in the strontium carbonate can cause distortion of the aluminum titanate lattice in the one-time synthesis sintering process, while other single additives or composite additives cannot ensure that the aluminum titanate lattice distortion remains stable in one-time synthesis, and must be synthesized twice or three times to ensure the aluminum titanate lattice distortion, thereby improving the stability, mechanical strength and thermal shock resistance of the aluminum titanate.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] The aluminum titanate ceramic liquid lifting pipe has excellent performance, and compared with the traditional method, the raw material powder does not need to be pretreated and sintered, because the zinc oxide and strontium carbonate are simultaneously added to refine the crystal grains and reduce the sintering temperature of the aluminum titanate, and the prepared aluminum titanate is not decomposed, so that the aluminum titanate ceramic can be synthesized at one time, that is, only one sintering is needed, thereby more time and energy are saved, energy saving and high efficiency are realized, and large-scale industrial production is more favorable. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is the SEM electron microscope graph of the liquid lifting pipe of Example 5 (magnification 250);

[0026] Figure 2 is the SEM electron microscope graph of the liquid lifting pipe of Example 5 (magnification 2000). DETAILED DESCRIPTION

[0027] The technical solutions of the present application will be described in detail below in combination with examples.

[0028] All raw materials used in the examples are commercially available, except for special instructions.

[0029] Example 1

[0030] The method for synthesizing the aluminum titanate ceramic liquid lifting pipe at one time according to the present application comprises the following steps:

[0031] (1) 45 kg of aluminum oxide, 50 kg of titanium dioxide, 2.5 kg of strontium carbonate and 2.5 kg of zinc oxide are mixed, water is used as a medium, alumina balls are used as grinding media, alumina lining is used as grinding lining, and the material, water and alumina ball are proportioned into a ball mill according to the mass ratio of 1:0.8:-2.5, and then finely ground to D50=2 μm, and then transported to a spray drying tower by a slurry pump for spray drying until the volatile matter is less than or equal to 0.5%, and then passed through an 80 # screen to obtain a powder after standing for 24 hours;

[0032] (2) The powder is uniformly loaded into a shaped rubber sleeve after being passed through an 80 # screen, and a cold isostatic pressing device is used to slowly pressurize to 120 MPa, and the pressure is maintained for 6 minutes, and then slowly depressurized to obtain a green body;

[0033] (3) The green body is processed and sintered at 1500 DEG C.

[0034] Example 2

[0035] The method for synthesizing the aluminum titanate ceramic liquid lifting pipe at one time according to the present application comprises the following steps:

[0036] (1) Al2O346kg, TiO250kg, SrCO22.0kg, ZnO 2.0kg are mixed, water is used as medium, alumina ball is used as grinding medium, alumina lining is used as grinding lining, and the material, water and alumina ball are proportioned into a ball mill at a mass ratio of 1:0.8:2.5, and fine grinding is performed to D50=2 μm, and the powder is sprayed and dried in a spray drying tower by using a mud pump to spray and dry to volatile matter≤0.5%, and then the powder is screened through an 80 # screen, and the powder is left to stand for 24 h to obtain a powder;

[0037] (2) The powder is screened through an 80 # screen, and then the powder is uniformly filled into a sizing rubber sleeve, cold isostatic pressing equipment is used to slowly press to 120 MPa, pressure is maintained for 6 min, and slow pressure reduction is performed to obtain a green body;

[0038] (3) After the green body is processed, sintering is performed at 1520 ℃ to form a shape.

[0039] Example 3

[0040] The method for synthesizing an aluminum titanate ceramic riser pipe in one step provided by the application comprises the following steps:

[0041] (1) Al2O345kg, TiO251kg, SrCO22.0kg, ZnO 2.0kg are mixed, water is used as medium, alumina ball is used as grinding medium, alumina lining is used as grinding lining, and the material, water and alumina ball are proportioned into a ball mill at a mass ratio of 1:0.8:2.5, and fine grinding is performed to D50=2 μm, and the powder is sprayed and dried in a spray drying tower by using a mud pump to spray and dry to volatile matter≤0.5%, and then the powder is screened through an 80 # screen, and the powder is left to stand for 24 h to obtain a powder;

[0042] (2) The powder is screened through an 80 # screen, and then the powder is uniformly filled into a sizing rubber sleeve, cold isostatic pressing equipment is used to slowly press to 120 MPa, pressure is maintained for 8 min, and slow pressure reduction is performed to obtain a green body;

[0043] (3) After the green body is processed, sintering is performed at 1520 ℃ to form a shape.

[0044] Example 4

[0045] The method for synthesizing an aluminum titanate ceramic riser pipe in one step provided by the application comprises the following steps:

[0046] (1) Al2O346kg, TiO251kg, SrCO21.5kg, ZnO 1.5kg are mixed, water is used as medium, alumina ball is used as grinding medium, alumina lining is used as grinding lining, and the material, water and alumina ball are proportioned into a ball mill at a mass ratio of 1:0.8:2.5, and fine grinding is performed to D50=2 μm, and the powder is sprayed and dried in a spray drying tower by using a mud pump to spray and dry to volatile matter≤0.5%, and then the powder is screened through an 80 # screen, and the powder is left to stand for 24 h to obtain a powder;

[0047] (2) The powder is passed through an 80 # After being uniformly filled into a sizing rubber sleeve, the cold isostatic pressing equipment is used to slowly pressurize to 120 MPa, pressure is maintained for 7 min, and slow pressure reduction is performed to obtain a green body;

[0048] (3) After the green body is processed, sintering is performed at 1550 DEG C to form a product.

[0049] Example 5

[0050] The method for preparing the one-step synthesized aluminum titanate ceramic riser pipe comprises the following steps:

[0051] (1) 46 kg of aluminum oxide, 52 kg of titanium dioxide, 1.0 kg of strontium carbonate, and 1.0 kg of zinc oxide are mixed, water is used as a medium, aluminum oxide balls are used as grinding media, and aluminum oxide lining is used as a grinding lining, and the material, water, and aluminum oxide balls are proportioned into a ball mill according to a mass ratio of 1:0.8:2.5, and fine grinding is performed to D50 = 2 μm, and the slurry pump is used to transport and spray dry the powder in a spray drying tower to spray dry to a volatile content of less than or equal to 0.5%, and the powder is passed through an 80 # After being left to stand for 24 h, the powder is obtained;

[0052] (2) The powder is passed through an 80 # After being uniformly filled into a sizing rubber sleeve, the cold isostatic pressing equipment is used to slowly pressurize to 120 MPa, pressure is maintained for 7 min, and slow pressure reduction is performed to obtain a green body;

[0053] (3) After the green body is processed, sintering is performed at 1580 DEG C to form a product.

[0054] Performance test

[0055] The riser pipes obtained in Examples 1-5 are subjected to a performance test, and the obtained results are shown in Table 1.

[0056] Table 1 Performance test table of Examples 1-5

[0057]

[0058] As can be seen from the data in Table 1, the aluminum titanate ceramic riser pipe obtained in the application has excellent performance; as can be seen from Figure 1 、 Figure 2 It can be seen that the riser pipe obtained in the application is covered with pores on the surface, so that it has excellent thermal shock resistance. In summary, the product prepared in the application has excellent performance and realizes energy saving and high efficiency.

Claims

1. A method of synthesizing an aluminum titanate ceramic riser in one step, characterized by, It comprises the following steps: (1) mixing raw materials, ball milling, drying and sieving, and then standing and cooling to obtain powder; (2) sieving the powder and then performing cold isostatic pressing to shape the green body; (3) processing the green body and then sintering to form; The raw materials are composed of alumina, titanium dioxide, zinc oxide and strontium carbonate; The mass percentage of alumina, titanium dioxide, zinc oxide and strontium carbonate in the raw materials is respectively: Alumina 40%-48%; Titanium dioxide 44%-52%; Zinc oxide 1%-4%; Strontium carbonate 1%-4%; The sintering temperature is 1500-1600℃.

2. The method of claim 1, wherein the once-fired aluminum titanate ceramic riser is characterized by, Ball milling to a particle size D50=2-2.3μm.

3. The method of claim 1, wherein the once-fired aluminum titanate ceramic riser is characterized by, Drying to a volatile content ≤0.5%.

4. The method of claim 1, wherein the monolithic synthetic aluminum titanate ceramic riser is characterized by, Standing and cooling time ≥24h.

5. The method of claim 1, wherein the monolithic synthetic aluminum titanate ceramic riser is characterized by, In steps (1) and (2), the sieving is performed at 80°C. # screen.

6. The method of claim 1, wherein the monolithic synthetic aluminum titanate ceramic riser is characterized by, The specific process of step (2) is: after sieving the powder, it is loaded into a shaped rubber sleeve, and then a cold isostatic pressing device is used for pressing, pressure maintaining, pressure reduction, and then the green body is obtained.

7. The method of claim 6, wherein the monolithic synthetic aluminum titanate ceramic riser is characterized by, Pressing to 100-150MPa.

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