阅读说明：本技术 一种原位Al2O3颗粒增强铝基复合材料的制备方法 (In-situ Al2O3Preparation method of particle reinforced aluminum matrix composite ) 是由 陈刚 张婷 赵玉涛 张振亚 徐家盛 于 2020-06-18 设计创作，主要内容包括：本发明属铝基复合材料技术领域,具体涉及一种原位颗粒增强铝基复合材料及其制备方法。本发明将干燥后的煅烧高岭土与铝粉进行混合,将混合粉料在球磨罐内的氩气保护下进行球磨。向球磨后的混合粉末中加入镁粉,压制成预制块后进行烧结,然后将经烧结的预制块加入到A356铝合金熔体中,并进行机械搅拌,施加超声处理,静置除渣后浇铸获得原位Al<Sub>2</Sub>O<Sub>3</Sub>颗粒增强铝基复合材料。该方法所使用的反应粉末为煅烧高岭土,来源广泛,成本低廉,采用预制块的方法使颗粒与基体结合良好,制备工艺简单,可控性好,制备出的铝基复合材料增强颗粒分布均匀,增强颗粒与基体界面干净,性能优异,适合大规模化生产。(The invention belongs to the technical field of aluminum-based composite materials, and particularly relates to an in-situ particle reinforced aluminum-based composite material and a preparation method thereof. The method mixes the dried calcined kaolin with aluminum powder, and ball-milling the mixed powder under the protection of argon in a ball milling tank. Adding magnesium powder into the mixed powder after ball milling, pressing into a precast block, sintering, adding the sintered precast block into an A356 aluminum alloy melt, and mechanically stirringUltrasonic treatment is carried out, and in-situ Al is obtained by casting after standing and deslagging 2 O 3 A particulate reinforced aluminum matrix composite. The reaction powder used by the method is calcined kaolin, the source is wide, the cost is low, the combination of the particles and the matrix is good by adopting a precast block method, the preparation process is simple, the controllability is good, the prepared aluminum matrix composite reinforced particles are uniformly distributed, the interface between the reinforced particles and the matrix is clean, the performance is excellent, and the method is suitable for large-scale production.)

1. In-situ Al₂O₃The preparation method of the particle reinforced aluminum-based composite material is characterized by mixing dried calcined kaolin with aluminum powder, carrying out ball milling on the mixed powder under the protection of argon in a ball milling tank, adding magnesium powder into the mixed powder after ball milling, pressing into a precast block, sintering, adding the sintered precast block into an A356 aluminum alloy melt, mechanically stirring, applying ultrasonic treatment, standing for deslagging, and casting to obtain in-situ Al after in-situ slag removal₂O₃The particle reinforced aluminum matrix composite material comprises the following specific steps:

(1) mixing the dried calcined kaolin with aluminum powder, and placing the mixture into a ball milling tank for ball milling under the protection of argon;

(2) drying the mixed powder after ball milling, adding magnesium powder after sieving, pressing into a precast block after uniformly mixing, sintering under the protection of argon, cooling to room temperature along with a furnace, and taking out to obtain a sintered block;

(3) Melting an A356 aluminum alloy ingot, cooling to 740 ℃ along with 720 plus materials, refining, slagging off, standing, and heating to 850 ℃ along with 750 plus materials;

(4) weighing the sintered blocks obtained in the step (2), preheating, adding into the aluminum melt obtained in the step (3), and mechanically stirring to obtain a composite material melt;

(5) cooling the composite material melt obtained in the step (4) to 720-740 ℃, and applying ultrasonic treatment to uniformly disperse the particles;

(6) after the ultrasonic treatment is finished, standing, preserving heat, refining, removing slag, and casting in a metal mould to obtain in-situ Al₂O₃A particulate reinforced aluminum matrix composite.

2. An in-situ Al according to claim 1₂O₃The preparation method of the particle reinforced aluminum-based composite material is characterized in that in the step (1), the mass ratio of aluminum powder to calcined kaolin is 3-5: 1, the ball milling speed is 250-350rpm, and the ball milling time is 5-10 h.

3. An in-situ Al according to claim 1₂O₃The preparation method of the particle reinforced aluminum-based composite material is characterized in that in the step (2), the addition amount of magnesium powder is 0.1-0.3% of the mass of aluminum powder; the sintering temperature is 800-900 ℃, and the temperature is kept for 0.5-1 h.

4. An in-situ Al according to claim 1₂O₃The preparation method of the particle reinforced aluminum matrix composite is characterized in that in the step (4), the sintered blocks are weighed according to 10-20% of the mass of the aluminum melt; the preheating temperature is 150-; the rotating speed of the stirring paddle is 800-1200rpm, and the stirring time is 5-10 min.

5. An in-situ Al according to claim 1₂O₃The preparation method of the particle reinforced aluminum matrix composite is characterized in that in the step (5), the ultrasonic time is 10-15min, the frequency is 20kHz, and the power is 1 kW.

Technical Field

The invention belongs to the technical field of aluminum-based composite materials, and particularly relates to a preparation method of an in-situ particle reinforced aluminum-based composite material.

Background

The particle reinforced aluminum matrix composite material prepared by the in-situ method has excellent mechanical property, good oxidation resistance and corrosion resistance due to small size of reinforced particles and clean bonding interface with a matrix. The most common reinforcing particles currently used in situ aluminum matrix composites are mainly Al₂O₃TiC and TiB₂And the like. Wherein Al is₂O₃The grain hardness is higher, which can make the composite material taking it as the reinforcing phase have high specific strength, specific modulus and good wear resistance, so the in-situ Al₂O₃The particle reinforced aluminum matrix composite material has good application value.

In recent years, Al has been produced₂O₃The particle system is mainly concentrated on Al-ZrO₂、Al-TiO₂Al-CuO and Al-SiO₂In these systems, the raw materials used in the preparation of submicron or nanoparticle reinforced aluminum matrix composites are expensive, and the cost for preparing the composites is high. China has rich kaolin resources, and kaolin is a non-metal mineral product, and is clay and claystone which mainly comprises kaolinite clay minerals. The theoretical chemical composition of kaolin is 46.54% SiO₂39.5% of Al₂O₃13.96% of H₂O, kaolin minerals belong to the 1:1 type phyllosilicates. The kaolin is calcined in a calcining furnace to a certain temperature and time, and the structural water is removed, so that the physical and chemical properties of the kaolin are changed to meet certain use requirements.

The reinforcement particles in the in-situ particle reinforced aluminum-based composite material are generated through chemical reaction, and the differences of an in-situ system and a preparation process cause the problems in the field, including poor interface wettability, particle agglomeration, difficulty in adding reactants and the like. The wettability of the reinforcing phase and a matrix is affected due to the difference of the physicochemical properties of the reinforcing phase, fine particles generated in situ are easy to agglomerate in the melt, and particularly when the particles reach submicron or nanometer sizes, the small size effect causes the fine particles to be unevenly dispersed in the matrix, so that the performance of the composite material is limited to a higher degree, and the design requirement of the composite material is difficult to achieve. The mechanical stirring process drives the melt to continuously and circularly flow through a stirring device, so that the distribution of internal particles is changed. The process has low requirements on equipment, test places and other conditions, and can be used for preparing the composite material with high particle content. In addition, the aluminum melt is subjected to ultrasonic treatment, and the generated ultrasonic action can locally generate instantaneous high-temperature high-pressure and high-speed jet flow, so that particles in the melt are dispersed.

Through the search of the prior art documents, the Chinese patent publication numbers are: 109518033, publication date is: 2019.03.26, title of the invention: in-situ Al ₂O₃The preparation method of the particle reinforced aluminum-based composite material adopts CuO and AlNH as reaction powder₄(SO₄)₂、Zr(CO₃)₂In the method, rare earth compound is used as a reaction promoter, and foaming agent and K are added₂TiF and the like, are subjected to smelting reaction for 60-80min, extrusion casting molding, and then subjected to T5 or T6 heat treatment to finally prepare the particle reinforced aluminum matrix composite. The method has the problems of high raw material price, long reaction time, enhanced particle agglomeration and high preparation cost, and is not beneficial to the industrial production of the aluminum matrix composite.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention provides the in-situ particle reinforced aluminum-based composite material and the preparation method thereof, the production cost is low, the interface between the matrix and the reinforced particles in the prepared composite material is clean, the particles are uniformly distributed, the mechanical property is good, and the in-situ particle reinforced aluminum-based composite material is suitable for large-scale production.

The principle of the invention is as follows: calcined kaolins (Al) for use in the invention₂O₃·2SiO₂) Is amorphous, loose in internal structure and smooth in molten aluminumThe infiltration is facilitated, and the replacement reaction is carried out to produce Al₂O₃And (3) granules. The calcined kaolin has a density of 2.54-2.60g/cm³Density of aluminum of 2.70g/cm³Relatively close, provides conditions for the calcined kaolin particles to smoothly enter the aluminum melt. Furthermore, the addition of magnesium can result in Al ₂O₃Weakening and premature cracking of the particle surface, and replacing with a porous magnesium oxide layer to improve the wettability of the particles with the matrix, or directly with Al₂O₃The reaction produces spinel, which provides a nucleation core for preparing the reinforcing particles. For Al-Si alloy, the semi-solid temperature range is larger, and when the alloy temperature is in the semi-solid range, the semi-solid slurry is mechanically stirred, so that particles can be effectively dispersed in the alloy. The ultrasound generates nonlinear effect in the molten aluminum, the ultrasound can generate countless micro-cavities in the melt, the micro-cavities and the sound wave energy act simultaneously to intensify the movement and collision of melt molecules, and the gas mixed in the melt can be discharged through the micro-cavities, so the ultrasound can play a certain role in degassing and dispersing internal particles to the melt,

the invention is realized by the following technical scheme: mixing the dried calcined kaolin with aluminum powder, and carrying out ball milling on the mixed powder under the protection of argon in a ball milling tank. Adding magnesium powder into the mixed powder after ball milling, pressing into a precast block, sintering, adding the sintered precast block into an A356 aluminum alloy melt, mechanically stirring, applying ultrasonic treatment, standing for deslagging, and casting to obtain in-situ Al ₂O₃A particulate reinforced aluminum matrix composite.

As an improvement of the technical scheme, the method comprises the following specific implementation steps:

(1) mixing the dried calcined kaolin with aluminum powder, and placing the mixture into a ball milling tank for ball milling under the protection of argon, wherein the mass ratio of the aluminum powder to the calcined kaolin is 3-5: 1, the ball milling speed is 250-350rpm, and the ball milling time is 5-10 h;

(2) drying the mixed powder after ball milling, adding magnesium powder of 0.1-0.3 wt.% of the mass of the aluminum powder after sieving, pressing into a precast block after uniformly mixing, sintering under the protection of argon at the sintering temperature of 800-900 ℃, preserving heat for 0.5-1h, cooling to room temperature along with a furnace, and taking out;

(3) melting an A356 aluminum alloy ingot, cooling to 740 ℃ along with 720 plus materials, refining, slagging off, standing, and heating to 850 ℃ along with 750 plus materials;

(4) weighing the sintered blocks in the step (2) according to 10-20% of the mass of the aluminum melt, preheating, adding the preheated sintered blocks into the aluminum melt in the step (3), and mechanically stirring at the preheating temperature of 150-;

(5) cooling the composite material melt obtained in the step (4) to 720-;

(6) After the ultrasonic treatment is finished, standing, preserving heat, refining, removing slag, and casting in a metal mould to obtain in-situ Al₂O₃A particulate reinforced aluminum matrix composite.

The technical scheme of the invention has the following beneficial effects:

the reaction powder used by the method is calcined kaolin, the source is wide, the cost is low, the combination of the particles and the matrix is good by adopting a precast block method, the preparation process is simple, the controllability is good, the prepared aluminum matrix composite reinforced particles are uniformly distributed, the interface between the reinforced particles and the matrix is clean, the performance is excellent, and the method is suitable for large-scale production.

Drawings

FIG. 1 shows in-situ Al prepared in example 3₂O₃XRD diffraction pattern of the particle reinforced aluminum matrix composite;

FIG. 2 shows in-situ Al prepared in example 3₂O₃A microstructure photograph of the particle reinforced aluminum matrix composite;

table 1 shows the mechanical properties of the a356 matrix and the composites prepared in the examples.

Detailed Description

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following detailed description is given with reference to specific embodiments.