阅读说明：本技术 一种铸造用钛酸铝陶瓷及其制备方法 (Aluminum titanate ceramic for casting and preparation method thereof ) 是由 黄学辉 陈微 于 2020-06-03 设计创作，主要内容包括：本发明涉及一种铸造用钛酸铝陶瓷及其制备方法,以α-Al<Sub>2</Sub>O<Sub>3</Sub>和钛黄粉为原料,加入碳酸镁和二氧化硅作为稳定剂,各原料组分为：α-Al<Sub>2</Sub>O<Sub>3</Sub>53％～59％wt,钛黄粉37.58％～42.72％wt,稳定剂总量3％～6％,各原料经湿法球磨混合、造粒、冷等静压成型、烧制成钛酸铝陶瓷。本发明采用一步法直接制得钛酸铝材料,简化了制备工艺,大大节约生产成本,具有良好的经济效益,同时制备的材料机械强度大、热膨胀系数低,可以用来制备铸造用升液管、坩埚等产品。(The invention relates to aluminum titanate ceramic for casting and a preparation method thereof, which is prepared from alpha-Al 2 O 3 And titanium yellow powder as raw materials, adding magnesium carbonate and silicon dioxide as stabilizing agents, wherein the raw materials comprise: alpha-Al 2 O 3 53 to 59 percent of titanium yellow powder, 37.58 to 42.72 percent of titanium yellow powder and 3 to 6 percent of stabilizer, and the raw materials are ball-milled and mixed by a wet method, granulated, cold isostatic pressing molded and sintered to prepare the aluminum titanate ceramic. The invention adopts a one-step method to directly prepare the aluminum titanate material, simplifies the preparation process, greatly saves the production cost, has good economic benefit, simultaneously has high mechanical strength and low thermal expansion coefficient of the prepared material, and can be used for preparing products such as a riser tube, a crucible and the like for casting.)

1. The aluminum titanate ceramic for casting is directly fired by a one-step method, and is characterized in that the aluminum titanate ceramic is prepared from the following raw materials in parts by weight: alpha-Al₂O₃53-59 wt%, 37.58-42.72 wt% of titanium yellow powder and 3-6% of stabilizer, wherein the stabilizer is formed by compounding magnesium carbonate and silicon dioxide.

2. A preparation method of aluminum titanate ceramic for casting is characterized by comprising the following steps:

(1) ball milling the feedstock of claim 1 to a fineness;

(2) wet ball milling and mixing the ball milled raw materials by a planetary ball mill with a certain rotating speed according to the proportion of claim 1 to prepare slurry;

(3) pouring the slurry into a container, drying for 4 hours in an electrothermal blowing dry box at 110 ℃, grinding the formed powder by an agate mortar, sieving by a 100-mesh sieve, adding a proper amount of PVA (polyvinyl alcohol) aqueous solution for granulation, and ageing for 24 hours to form a mixture;

(4) prepressing the mixture by using a hydraulic press, wherein the pressure of the hydraulic press is 8MPa, and pressing by using an isostatic press, the pressure of the isostatic press is 120 MPa-140 MPa, and the pressing time is 5min, so as to prepare a green body;

(5) removing burrs at the corners of the pressed and molded green body, and then drying the green body in an oven at a constant temperature of 90-100 ℃ for 12-24 hours;

(6) and sintering the dried blank in a silicon-molybdenum furnace at the sintering temperature of 1420-1450 ℃ for 10-12 h.

3. The method for preparing aluminum titanate ceramic for casting according to claim 2, wherein the fineness of the raw material in the step (1) is 200 meshes.

4. The method for preparing aluminum titanate ceramic for casting according to claim 2, wherein the planetary ball mill of the step (2) has a rotation speed of 400r/min and a ball milling time of 12 h.

5. The method for preparing aluminum titanate ceramic for casting according to claim 4, wherein a medium used for ball milling is absolute ethyl alcohol, a ball mill used for ball milling is a zirconia ceramic ball mill, and the mass ratio of the raw material, the ball mill and the absolute ethyl alcohol is 1:3: 1.25.

6. The method for preparing an aluminum titanate ceramic for casting according to claim 2, wherein the sintering temperature in the step (6) is: the heating rate is 3-8 ℃/min below 1000 ℃, wherein the temperature is kept for 2h at 600 ℃, the heating rate is 2-5 ℃/min above 1000 ℃, and the temperature is kept for 3-5 h after the highest firing temperature is reached.

Technical Field

The invention relates to the technical field of ceramic preparation, in particular to aluminum titanate ceramic for casting and a preparation method thereof.

Background

With the rapid development of modern industry, especially the rise of fields such as automobile industry and aviation industry, the demand for ceramic materials with excellent high temperature resistance and thermal shock resistance is more and more urgent. Aluminum titanate (Al)₂TiO₅) Is a novel material integrating low expansion coefficient and high melting point, has the advantages of excellent thermal shock resistance, slag resistance, corrosion resistance and non-infiltration to various metals, and can be widely applied to the fields of glass, automobiles, thermal processing industry and the like due to the low thermal expansion coefficient and the excellent thermal shock resistance, such as catalysisThe catalyst carrier, the exhaust pipe, the internal combustion engine heat insulation, the metal metallurgy casting thermal shock resistant part and the like. However, the material has two fatal defects, so that the application of the material is greatly limited: firstly, the material is easy to decompose into rutile and corundum phases at the temperature of 750-1280 ℃, so that the excellent low expansion performance of the material is lost; secondly, a large amount of microcracks are generated inside the aluminum titanate crystals when the aluminum titanate crystals are cooled, and the mechanical strength of the aluminum titanate crystals at room temperature is greatly reduced.

The aluminum titanate ceramic lift tube is a key component of a low-pressure casting continuous casting machine, the quality and the production efficiency of cast aluminum products are directly influenced, and the cast aluminum lift tube has the defects of easy pollution of an aluminum source, short service life, sticking of aluminum liquid and the like, so that the aluminum titanate ceramic lift tube is developed by China abroad₃N₄The reaction sintered SiC ceramic lift tube has the outstanding advantages of no pollution to aluminum liquid, good erosion resistance and the like, and has long and stable service life, but has great obstruction in popularization and application in China due to high production cost and high price. The aluminum titanate is a high-temperature low-expansion material with lower price, has excellent thermal shock resistance and non-wetting property to aluminum liquid, and is an ideal material for replacing cast iron to manufacture the lift tube. At present, the aluminum titanate ceramic lift tube in China is mostly prepared by a two-step method, and research and application reports of direct one-step production are few.

Disclosure of Invention

In order to solve two fatal defects of aluminum titanate materials and provide a new idea for the production of domestic ceramic lift tubes, the invention provides aluminum titanate ceramics for casting and a preparation method thereof, and the specific technical scheme is as follows:

the aluminum titanate ceramic for casting is directly fired by a one-step method, and the aluminum titanate ceramic is prepared from the following raw materials in parts by weight: alpha-Al₂O₃53-59 wt%, 37.58-42.72 wt% of titanium yellow powder and 3-6% of stabilizer, wherein the stabilizer is formed by compounding magnesium carbonate and silicon dioxide.

A preparation method of aluminum titanate ceramic for casting comprises the following steps:

(1) ball milling the feedstock of claim 1 to a fineness;

(2) wet ball milling and mixing the ball milled raw materials by a planetary ball mill with a certain rotating speed according to the proportion of claim 1 to prepare slurry;

(3) pouring the slurry into a container, drying for 4 hours in an electric heating forced air drying oven at 110 ℃, grinding the formed powder by an agate mortar, sieving by a 100-mesh sieve, adding a proper amount of PVA aqueous solution for granulation, and ageing for 24 hours to form a mixture;

(4) prepressing the mixture by using a hydraulic press, wherein the pressure of the hydraulic press is 8MPa, and pressing by using an isostatic press, the pressure of the isostatic press is 120 MPa-140 MPa, and the pressing time is 5min, so as to prepare a green body;

(5) removing burrs at the corners of the pressed and molded green body, and then drying the green body in an oven at a constant temperature of 90-100 ℃ for 12-24 hours;

(6) and (3) sintering the dried blank in a silicon-molybdenum furnace at the sintering temperature of 1420-1450 ℃ for 10-12 h.

Further, the fineness of the raw materials in the step (1) is 200 meshes.

Further, the rotating speed of the planetary ball mill in the step (2) is 400r/min, and the ball milling time is 12 h.

Furthermore, a medium used for ball milling is absolute ethyl alcohol, a ball mill used is a zirconia ceramic ball mill, and the mass ratio of the raw materials, the ball mill and the absolute ethyl alcohol is 1:3: 1.25.

Further, the sintering temperature in the step (6) is as follows: the heating rate is 3-8 ℃/min below 1000 ℃, wherein the temperature is kept for 2h at 600 ℃, the heating rate is 2-5 ℃/min above 1000 ℃, and the temperature is kept for 3-5 h after the highest firing temperature is reached.

Has the advantages that:

the invention utilizes alpha-Al₂O₃And titanium yellow powder are used as raw materials, magnesium carbonate and silicon dioxide are added as stabilizing agents to prepare the aluminum titanate ceramic, so that the mechanical strength of the aluminum titanate ceramic is improved while the excellent thermal expansion performance of the aluminum titanate ceramic is ensured; the ceramic lift tube and other materials for casting prepared by the trial ceramics can save energy consumption, simplify the process, save production cost and have good economic benefit.

Drawings

FIG. 1 is a comparison chart of X-ray diffraction patterns of examples 1 to 4 of the present invention;

in the figure: 1 is the X-ray diffraction pattern profile of example 1, 2 is the X-ray diffraction pattern profile of example 2, 3 is the X-ray diffraction pattern profile of example 3, and 4 is the X-ray diffraction pattern profile of example 4;

FIG. 2 is a comparison graph of thermal expansion coefficients of examples 1 to 4 of the present invention;

in the figure: the thermal expansion coefficient curve of example 1 is shown as 1, the thermal expansion coefficient curve of example 2 is shown as 2, the thermal expansion coefficient curve of example 3 is shown as 3, and the thermal expansion coefficient curve of example 4 is shown as 4.

Detailed Description

The invention is further described with reference to the following figures and specific embodiments:

as shown in fig. 1-2, an aluminum titanate ceramic for aluminum alloy casting is directly fired by a solid-phase reaction one-step method, and the raw materials and the mixture ratio of the green body are as follows: alpha-Al₂O₃53 to 59 percent of titanium yellow powder, 37.58 to 42.72 percent of titanium yellow powder and 3 to 6 percent of stabilizer, wherein the stabilizer is formed by compounding magnesium carbonate and silicon dioxide.