CN104532046B - Method for preparing nano-aluminum-nitride reinforced aluminum-based composite semi-solid slurry based on ultrasonic and mechanical vibration combination - Google Patents

Abstract

A method for preparing semi-solid slurry of nano-aluminum nitride-reinforced aluminum-based composite materials based on ultrasonic and mechanical vibration. Firstly, nano-aluminum nitride particles and aluminum powder are mixed at a mass ratio of 1:1-2:3 at 60-70rpm Ball mill for 50-60 hours; put the mixed powder into the crucible and heat it to 660-670°C; air-cool, crush, and sieve; put the aluminum alloy into the crucible and melt it at 700-750°C, press nano-aluminum nitride particles % of the aluminum alloy melt, add the above-mentioned sieved mixed powder into the aluminum alloy melt for 5-10 minutes, introduce 20KHz, 1-3KW high-energy ultrasound at the same time, and then continue ultrasonication for 5 ～10min; reduce the melt temperature to 5～15℃/min to the semi-solid temperature range of the alloy, and apply mechanical vibration treatment, power 1.5KW, frequency 400～600Hz and amplitude 0.5～1.5mm. The primary α-Al phase in the structure of the aluminum-based nano-composite material obtained by the invention is fine and evenly distributed, the nano-aluminum nitride particles are evenly distributed, there is no agglomeration phenomenon, the process cost is low, simple, safe and reliable, and easy to operate.

Description

A nano-aluminum nitride-reinforced aluminum-matrix composite prepared based on ultrasonic and mechanical vibration Material semi-solid slurry method

technical field

The invention belongs to the field of metal material preparation, in particular to a method for preparing semi-solid slurry of aluminum-based composite materials.

Background technique

During the forming process, the semi-solid alloy has stable mold filling, low thermal stress, less shrinkage cavity and shrinkage defects, and a net near-formation. Particle-reinforced aluminum matrix composites have many advantages such as specific strength, high specific stiffness, high wear resistance, and high vibration damping. Aluminum nitride particles are an ideal reinforcement phase because of their good physical, chemical, mechanical and thermal properties, and have attracted the attention of many scholars. Micron particles can improve the yield strength and ultimate compressive strength of the matrix, but make the ductility of the matrix worse. Nanoparticles can significantly improve the elastic modulus, yield strength, wear resistance and high temperature creep of the matrix while maintaining a low content, so they are gradually being valued. A large number of studies have found that the wettability of nano-ceramic particles and aluminum alloy melt is poor, and the state in the melt is unstable. However, the preparation of nanocomposites by traditional processes has problems such as easy agglomeration of nanoparticles, low content, complex process, and limited molding, which greatly affects the potential of improving the performance of aluminum-based nanocomposites.

Contents of the invention

The purpose of the present invention is to provide a method for preparing semi-solid slurry of nano-aluminum nitride particles reinforced aluminum-based composite materials

The present invention is achieved through the following technical solutions.

The preparation method of the present invention is as follows: first, mix the nano-aluminum nitride particles and the aluminum powder and perform ball milling for 50-60 hours, wherein the mass ratio of the nano-aluminum nitride particles to the aluminum powder is 1:1-2:3, and the ball-milling speed is 60～70rpm; put the mixed powder into the crucible to heat, the temperature is controlled at 660～670℃; air cooling, crushing, and sieving, wherein the mesh size is 1000～850μm; put the aluminum alloy into the crucible to heat and melt , when the temperature is 700-750°C, the added amount of nano-aluminum nitride particles is 1-4wt.% of the aluminum alloy melt, and the above-mentioned mixed powder after sieving is added to the aluminum alloy melt, and the addition time is 5-10 minutes, introduce high-energy ultrasound into the aluminum alloy melt during the addition process, the ultrasonic frequency is 20KHz, the power is 1-3KW, and then continue the ultrasonic treatment for 5-10 minutes; the melt temperature is reduced to the semi-solid temperature range of the alloy, and the cooling rate The temperature is 5-15°C/min, and mechanical vibration treatment is applied during this process. The vibration power is 1.5KW, the frequency is 400-600Hz, and the amplitude is 0.5-1.5mm; the nano-aluminum nitride-reinforced aluminum matrix composite material semi-solid slurry can be obtained.

Pure aluminum particles have better plasticity and are easily pressed into by ceramic particles. Low energy ball milling disperses the particles as well as possible while avoiding harmful chemical reactions. The effect of melt surface tension can make it difficult for small particles to join, while large particles can easily overcome this resistance due to their own gravity. Ultrasound can greatly promote the cavitation produced by the melt, and the acoustic flow can greatly promote the wetting and dispersion of particles. The sine wave generated by mechanical vibration can propagate in the medium and produce strong impact force.

The particle size of nano-aluminum nitride and aluminum in the present invention is preferably 30-100 nm for nano-aluminum nitride and 58-75 μm for aluminum.

The primary α-Al phase in the structure of the aluminum-based nano-composite material obtained by the invention is fine and evenly distributed, and the nano-aluminum nitride particles are evenly distributed without agglomeration. The process is low in cost, simple, safe and reliable, and easy to operate.

Description of drawings

Fig. 1 is the microstructure of the semi-solid A356 aluminum-based nanocomposite slurry prepared by the present invention.

detailed description

The invention will be further illustrated by the following examples.

Example 1.

First, mix the nano-aluminum nitride particles and aluminum powder for ball milling for 60 hours, wherein the mass ratio of nano-aluminum nitride particles to aluminum powder is 2:3, and the ball milling speed is 70rpm; put the mixed powder into the crucible for heating, and the temperature is controlled at 660°C; air cooling, crushing, and sieving, the mesh size of which is 850μm; put the 7075 aluminum alloy into the crucible to heat and melt, at a temperature of 700°C, the amount of nano-aluminum nitride particles added is the aluminum alloy melting The amount of 1wt.% of the body, the above-mentioned mixed powder after sieving is added to the 7075 aluminum alloy melt, the addition time is 5min, and high-energy ultrasound is introduced into the aluminum alloy melt during the addition process, the ultrasonic frequency is 20KHz, and the power is 1KW , and then continue ultrasonic treatment for 5 minutes; reduce the melt temperature to 635 ° C, the cooling rate is 5 ° C / min, this process is applied mechanical vibration treatment, vibration power 1.5KW, frequency 400Hz and amplitude 0.5mm; nano aluminum nitride can be obtained Reinforced semi-solid slurry for aluminum matrix composites.

Example 2.

First, mix the nano-aluminum nitride particles and aluminum powder for ball milling for 50 hours, wherein the mass ratio of nano-aluminum nitride particles to aluminum powder is 1:1, and the ball milling speed is 60rpm; put the mixed powder into a crucible for heating, and the temperature is controlled at 670°C; air cooling, crushing, and sieving, the mesh size of which is 1000μm; put the 6063 aluminum alloy into the crucible to heat and melt, at a temperature of 750°C, the amount of nano-aluminum nitride particles added is the aluminum alloy melting The amount of 2wt.% of the body, the above-mentioned mixed powder after sieving is added to the 6063 aluminum alloy melt, the addition time is 10min, and high-energy ultrasound is introduced into the aluminum alloy melt during the addition process, the ultrasonic frequency is 20KHz, and the power is 2KW , and then continue ultrasonic treatment for 5 minutes; reduce the melt temperature to 652 ° C, the cooling rate is 10 ° C / min, this process is applied mechanical vibration treatment, vibration power 1.5KW, frequency 500Hz and amplitude 0.5mm; nano-aluminum nitride can be obtained Reinforced semi-solid slurry for aluminum matrix composites.

Example 3.

First, mix the nano-aluminum nitride particles and aluminum powder for ball milling for 60 hours, wherein the mass ratio of nano-aluminum nitride particles to aluminum powder is 1:1, and the ball milling speed is 70rpm; put the mixed powder into a crucible for heating, and the temperature is controlled at 660°C; air-cooled, crushed, and sieved, with a mesh size of 850 μm; put the A356 aluminum alloy into a crucible to heat and melt, and at a temperature of 700°C, the amount of nano-aluminum nitride particles added is The amount of 1wt.% of the body, the above-mentioned mixed powder after sieving is added to the A356 aluminum alloy melt, the addition time is 5min, and high-energy ultrasound is introduced into the aluminum alloy melt during the addition process, the ultrasonic frequency is 20KHz, and the power is 1KW , and then continue ultrasonic treatment for 5 minutes; reduce the melt temperature to 605 ° C, the cooling rate is 15 ° C / min, this process is applied mechanical vibration treatment, vibration power 1.5KW, frequency 600Hz and amplitude 1.5mm; nano-aluminum nitride can be obtained Reinforced semi-solid slurry for aluminum matrix composites.

Accompanying drawing 1 is the structure of the semi-solid A356 aluminum-based nanocomposite slurry obtained under the conditions of Example 3. It can be seen from the figure that no coarse primary dendrites appear in the obtained aluminum-based composite structure, and the primary α-Al The phase is crushed by the strong impact force generated by the ultrasonic cavitation effect and mechanical vibration, and is obviously refined. Ultrasonic cavitation and acoustic flow make the nano-aluminum nitride powder evenly distributed in the melt.

Claims (2)

1. A method for preparing nano-aluminum nitride-reinforced aluminum matrix composite semi-solid slurry based on ultrasonic and mechanical vibration, which is characterized in that nano-aluminum nitride particles are first mixed with aluminum powder and ball-milled for 50-60 hours, wherein nano-nitrogen The mass ratio of aluminum oxide particles to aluminum powder is 1:1~2:3, and the ball milling speed is 60~70rpm; put the mixed powder into the crucible and heat it, and the temperature is controlled at 660~670°C; air cooling, crushing, and sieving , wherein the mesh size is 1000-850 μm; put the aluminum alloy into the crucible to heat and melt, and when the temperature is 700-750 ° C, the amount of nano-aluminum nitride particles added is 1-4wt.% of the aluminum alloy melt Add the above-mentioned sieved mixed powder into the aluminum alloy melt for 5-10 minutes. During the addition process, introduce high-energy ultrasound into the aluminum alloy melt. The ultrasonic frequency is 20KHz and the power is 1-3KW. Continue ultrasonic treatment for 5-10 minutes; reduce the melt temperature to the semi-solid temperature range of the alloy at a cooling rate of 5-15°C/min. During this process, apply mechanical vibration treatment with a vibration power of 1.5KW, a frequency of 400-600Hz and an amplitude of 0.5-1.5 mm. 2. The method for preparing nano-aluminum nitride-reinforced aluminum matrix composite semi-solid slurry based on ultrasonic and mechanical vibration according to claim 1, characterized in that the particle size of said nano-aluminum nitride and aluminum is nano-nitrogen Aluminum 30~100nm, aluminum 58~75μm.