CN100537801C - A kind of preparation method of aluminum matrix composite - Google Patents

Abstract

A kind of preparation method of aluminum matrix composite, wherein, this method comprises the aluminium of molten state and KBF ₄, K ₂TiF ₆And TiO ₂Mix, be cooled to 500-600 ℃ of reaction then, heat up again and make said mixture to molten state continue reaction, remove by product, obtain the aluminum matrix composite precursor, make described aluminum matrix composite precursor maintain molten state, and the aluminum matrix composite precursor of this molten state is mixed with magnesium, copper.Parameters such as tensile strength, yield strength, elongation at break and Young's modulus by the goods A-frame of the aluminum matrix composite die cast that adopts method provided by the invention to obtain all are significantly improved, the good mechanical properties of the goods that the aluminum matrix composite that adopts method of the present invention to obtain makes is described, especially more excellent in the mechanical property that adopts the goods that obtain after the Hpdc moulding.

Description

A kind of preparation method of aluminum matrix composite material

technical field

The invention relates to a preparation method of a composite material, more specifically, to a preparation method of an aluminum-based composite material.

Background technique

Aluminum matrix composites have excellent physical and mechanical properties such as high specific strength, high specific modulus, high temperature resistance, wear resistance, small thermal expansion coefficient, and stable size. They are used in aerospace, military defense, automobiles, electronic instruments and other industries Has a wide range of applications. According to the different states of the two reaction components participating in the synthesis of the reinforcing phase, the preparation method of the aluminum matrix composite mainly includes three reaction modes: gas-liquid, solid-liquid, and solid-solid.

Gas-liquid reaction method, also known as VIS method. The principle of this process is to use inert gas as a carrier, pass the gas containing C or N into the superalloy liquid, make the C or N in the gas decomposition react with the alloy liquid, and form fine, dispersed and stable particles in the alloy matrix. , high hardness, high elastic modulus of carbide or nitride, after cooling and solidification, a thermodynamically stable metal matrix composite material containing a ceramic particle reinforcement phase is formed.

Solid-liquid reaction method, which is composed of direct metal oxidation method (DIMOXTM) and metal pressureless impregnation method (PRIMEXTM). The DIMOXTM method is to oxidize metals and their alloys under molten conditions to prepare metal matrix composites containing ceramic particle reinforcement phases.

The PRIMEXTM method uses non-oxidizing gas. In this process, two processes occur at the same time: one is the penetration of liquid metal into ceramic preforms under the action of ambient atmosphere; the other is the reaction of liquid metal and surrounding gas to produce new enhanced particles. The study found that the quantity and size of AlN formed in situ mainly depends on the infiltration rate of Al liquid, and the infiltration rate of Al liquid is related to the partial pressure of _N2 in the ambient atmosphere, the temperature and composition of the melt. Therefore, the composite material The structure and properties are easily controlled by adjusting the composition of the melt, the partial pressure of _N2 and the processing temperature.

XDTM method, this method was invented by American Martin Marietta laboratory. It mixes two solid reactive element powders and metal matrix powder evenly and degasses after compaction, then rapidly heats the compact to a temperature above the melting point of the metal matrix, and the reactant elements undergo an exothermic chemical reaction in the melt to form Reinforcement phase ceramic particles. Using this technology to prepare composite materials, the reinforcing phase is wetted by the liquid metal, and the interface is firmly bonded, which is becoming a hot spot in the current research on composite materials. However, too fine particles will greatly increase the viscosity of the melt, so it is difficult to further cast the material.

The solid-solid reaction method, also known as mechanical alloying, is to grind different powders in a high-energy ball mill, and the powders are deformed by extrusion, interatomic diffusion or solid-state reaction to form alloys.

CN1740354A discloses a preparation method of an in-situ particle reinforced high temperature resistant aluminum matrix composite material. The components and weight percentages of the in situ particle reinforced high temperature resistant aluminum matrix composite material obtained by the method are: 11-13% Si, 0.5- 1.5% Mg, 0.8-1.3% Cu, 0.8-1.5% Ni, 1-20% TiB ₂ , the balance is Al; the preparation method includes the following steps:

(1) Add ZL102 alloy and Al-Si intermediate alloy or industrial pure aluminum into the crucible, heat up after melting, and cover with a covering agent, which is made of aluminum alloy refined sodium-free covering agent;

(2) Mix KBF ₄ and KTiF ₆ evenly, add to the melt after drying, and perform mechanical stirring;

(3) After the reaction finishes, take out the by-products, add industrial pure Mg, Al-Ni and Al-Cu master alloy, remove the scum, and leave it in a vacuum;

(4) Assemble the middle partition, riser, mold, and low-pressure molding.

The mechanical properties of the aluminum-based composite material obtained by this method are unsatisfactory after low-pressure forming. After the material is formed by high-pressure die-casting, the properties of the product such as tensile strength and elastic modulus are relatively poor.

Contents of the invention

The purpose of the present invention is to overcome the defects of the unsatisfactory mechanical properties of the product obtained by die-casting the aluminum-based composite material obtained by the existing preparation method, and to provide an aluminum-based composite material that makes the product obtained by die-casting have good mechanical properties. Preparation.

The invention provides a method for preparing an aluminum-based composite material, wherein the method comprises uniformly mixing molten aluminum with KBF ₄ , K ₂ TiF ₆ and TiO ₂ , then lowering the temperature to 500-600°C for reaction, and then raising the temperature to make the The above-mentioned mixture is continuously reacted to a molten state, and by-products are removed to obtain an aluminum-based composite material precursor, and the aluminum-based composite material precursor is maintained in a molten state, and the molten aluminum-based composite material precursor is mixed with magnesium, copper, and mix.

The parameters such as the tensile strength, yield strength, elongation at break and modulus of elasticity of the product triangular bracket obtained by die-casting the aluminum-based composite material obtained by the method provided by the present invention are all significantly improved, indicating that the method of the present invention is used to obtain The mechanical properties of the products made of aluminum-based composite materials are good, especially the mechanical properties of the products obtained after high-pressure die-casting are more excellent.

Detailed ways

According to the method provided by the present invention, the method includes mixing molten aluminum with KBF ₄ , K ₂ TiF ₆ and TiO ₂ , then lowering the temperature to 500-600°C for reaction, and then raising the temperature to make the above-mentioned mixture continue to react in a molten state to remove by-products. product, obtaining an aluminum-based composite material precursor, maintaining the aluminum-based composite material precursor in a molten state, and mixing the molten aluminum-based composite material precursor with magnesium and copper.

Raising the temperature to bring the mixture of aluminum and KBF ₄ , K ₂ TiF ₆ and TiO ₂ to a molten state means that aluminum, KBF ₄ , K ₂ TiF ₆ and TiO ₂ are all in a molten state. The temperature of the molten state is 1200-1900°C, preferably 1300-1700°C.

Preferably, the method of mixing molten aluminum with KBF ₄ , K ₂ TiF ₆ and TiO ₂ includes, under stirring, spraying KBF ₄ , K ₂ TiF ₆ and TiO ₂ powders into the molten aluminum uniformly , fully mix KBF ₄ , K ₂ TiF ₆ and TiO ₂ powder with molten aluminum with the help of stirring shear force to ensure that KBF ₄ , K ₂ TiF ₆ and TiO ₂ can be evenly distributed in the aluminum matrix composite .

The feed weight ratio of aluminum to KBF ₄ , K ₂ TiF ₆ and TiO ₂ is 1:0.03-1.2:0.03-1.2:0.1-0.4, preferably 1:0.05-1:0.05-1:0.15-0.35.

According to the method of the present invention, in order to prevent the molten aluminum from being oxidized, preferably, the mixing of the molten aluminum with KBF ₄ , K ₂ TiF ₆ and TiO ₂ is carried out in an inert gas, and the inert gas means not mixed with Any gas or gas mixture in which the reactants and products react chemically, such as nitrogen, one or more of the zero-group gases of the periodic table, preferably one or more of argon, nitrogen and helium.

In order to thoroughly mix KBF ₄ , K ₂ TiF ₆ and TiO ₂ with the molten aluminum by means of the shearing force of the stirring, the stirring is preferably performed under high-speed stirring, and the stirring speed is preferably 500-800 rpm.

The feed weight ratio of aluminum, magnesium and copper is 1:0.01-0.08:0.02-0.1.

In order to further improve the mechanical properties of the aluminum-based composite material, preferably, the method further includes mixing the molten aluminum-based composite material precursor with zinc and chromium, and mixing the molten aluminum-based composite material precursor with zinc and The mixing of chromium can be carried out while, before or after the molten aluminum matrix composite precursor is mixed with magnesium and copper, preferably while the molten aluminum matrix composite precursor is mixed with magnesium and copper, the molten The aluminum matrix composite precursor in the as-state is mixed with zinc and chromium. The feed weight ratio of aluminum to zinc and chromium is 1:0-0.2:0-0.2, preferably 1:0.1-0.2:0.1-0.2.

According to the present invention, after mixing molten aluminum with KBF ₄ , K ₂ TiF ₆ and TiO ₂ uniformly, the purpose of reducing the reaction temperature of aluminum with KBF ₄ , K ₂ TiF ₆ and TiO ₂ to 500-600°C is to make The obtained aluminum matrix composites have good mechanical properties. Since the semi-solid temperature of the matrix aluminum is 565°C, the reaction at 550-570°C, which is close to the semi-solid temperature of the matrix aluminum, can make the obtained aluminum matrix composite material have better mechanical properties; it can also be die-cast from this material , reduce defects such as subcutaneous pores and porosity inherent in conventional die castings, improve casting quality, and increase mold life. Therefore, it is preferable to reduce the reaction temperature of the aluminum with KBF ₄ , K ₂ TiF ₆ and TiO ₂ to 550-570°C reaction. The time for the reaction at 500-600°C, preferably 550-570°C, can be more than 1 minute. After the reaction time exceeds 60 minutes, the properties of the obtained aluminum-based composite material have not changed significantly, so at 500-600°C °C, preferably 550-570 °C, the reaction time is preferably 5-60 minutes.

The purpose of heating the mixture of molten aluminum, KBF ₄ , K ₂ TiF ₆ and TiO ₂ at 500-600°C to continue the reaction is to make the reaction more thorough. The reaction time in the molten state of the reaction mixture can be greater than 1 minute. After the reaction time exceeds 10 minutes, the performance of the obtained aluminum-based composite material has no obvious change. Therefore, the reaction time is preferably at the melting temperature of aluminum. 5-10 minutes.

During the reaction, the by-products generated include potassium salts and _Al2O3 oxide inclusions generated during the reaction, and the method for removing the _by -products is well known to those skilled in the art. Generally speaking, the removal of the by-products The method includes adding scouring agent and/or passing inert gas into the mixed melt of aluminum and KBF ₄ , K ₂ TiF ₆ and TiO ₂ before mixing the precursor of aluminum matrix composite material with magnesium and copper.

The type and amount of the scouring agent are known to those skilled in the art, such as, the scouring agent can be selected from one or more of KCl, NaCl, NaSiF ₆ , Na ₃ AlF ₆ , the scouring agent The weight ratio of the added amount to the total added amount of aluminum, KBF ₄ , K ₂ TiF ₆ and TiO ₂ is 0.01-0.05:1.

Adding inert gas can make the melt produce bubbles, and these bubbles can absorb Al ₂ O ₃ inclusions during the floating process, so that the above floats into the slag on the surface of the mixture, and the by-products are removed while the slag is pulled out . In addition, the inert gas can also absorb the hydrogen generated by the reaction during the flotation process and escape into the atmosphere, thereby reducing the concentration of hydrogen in the mixture. The inert gas may be introduced into the mixture through a conduit, such as a graphite conduit. The type and amount of the inert gas are known to those skilled in the art, and are selected from gases that are neither soluble in the melt nor react with the melt and hydrogen, such as nitrogen, one of the zero-group gases of the periodic table or Several kinds.

The method of die-casting the aluminum-based composite material is well known to those skilled in the art. For example, the forming method can adopt low-pressure forming or high-pressure forming. In the present invention, the method of high-pressure forming is preferably used for die-casting the aluminum-based composite material. The high-pressure forming method includes preheating the die-casting mold to 200-300°C, then pouring the molten aluminum-based composite material into the cavity of the die-casting mold, and performing pressurized die-casting and filling of the aluminum-based composite material. The mold filling pressure is 60-110 MPa, and the highest pressure is maintained for 5-15 seconds, so that the obtained product is completely solidified and then the die-casting operation is completed to obtain a product obtained by pressing and molding the aluminum-based composite material.

The present invention will be further described through specific examples below.

Example 1

This example illustrates the preparation method of the aluminum matrix composite material and product provided by the present invention.

At 720°C, add 80 grams of industrial pure aluminum to the resistance furnace to melt the aluminum, then, under the protection of nitrogen, and at a stirring speed of 600 rpm, mix 4 grams of KBF ₄ and 4 grams of K ₂ TiF ₆ and 12 grams of _TiO2 powder are evenly sprayed into the molten aluminum, fully mixed with the molten aluminum, then, the temperature is lowered to 565 ° C, under the protection of nitrogen, and the reaction is stopped at a stirring speed of 650 rpm for 30 minutes, and then the stirring is stopped. Then raise the temperature to bring the above mixture to a molten state (1300° C.), react for 8 minutes, then add 2 grams of scouring agent NaSiF ₆ , and stir to remove by-products to obtain an aluminum-based composite material precursor. The aluminum-based composite material precursor is continued Maintain the molten state (1300° C.), add 1.2 grams of industrial pure Mg and 2.4 grams of Cu to the molten aluminum matrix composite material precursor, stir and mix evenly, and remove scum to obtain an aluminum matrix composite material.

Preheat the triangular bracket die-casting mold to 220°C, set the die-casting process parameters, the process parameters include two positions set to 280 ± 30 mm, one position set to 130 ± 30 mm, mold opening time is 4.5 ± 2 seconds, The ejection delay is 4.0±2 seconds, the pressurization speed is 4.0±2 turns, then the cavity is closed, the aluminum-based composite material melt obtained above is poured, and the mold is pressurized and die-casted until the extrusion pressure reaches 110 MPa The highest pressure, maintain the highest die-casting pressure for 5 seconds, until the composite material casting is completely solidified, the product tripod A1 provided by the present invention is obtained. After die-casting, the product A1 was subjected to T6 heat treatment.

Example 2

This example illustrates the preparation method of the aluminum matrix composite material and product provided by the present invention.

At 720°C, add 80 grams of industrial pure aluminum to the resistance furnace to melt the aluminum, then, under the protection of nitrogen, and at a stirring speed of 650 rpm, mix 14 grams of KBF ₄ and 12 grams of K ₂ TiF ₆ and 16 grams of _TiO2 powder are evenly sprayed into the molten aluminum, fully mixed with the molten aluminum, then cooled to 565 ° C, under the protection of nitrogen, and reacted at a stirring speed of 650 rpm for 40 minutes, then stopped stirring, and then Heat up the above mixture to a molten state (1350° C.), react for 5 minutes, then add 1.7 grams of KCl scouring agent, and stir to remove by-products to obtain an aluminum-based composite material precursor, which continues to be maintained at molten state (1350° C.), and 1.6 grams of industrial pure Mg and 3.2 grams of copper were added to the molten aluminum-based composite material precursor, stirred and mixed evenly, and scum was removed to obtain an aluminum-based composite material.

Preheat the triangular bracket die-casting mold to 250°C, and set the die-casting process parameters. The process parameters include setting the position of two blocks at 280±30 mm, and the position of one block at 130±30 mm, and the mold opening time is 4.5±2 seconds , the ejection delay is 4.0±2 seconds, the pressurization speed is 4.0±2 turns, then the cavity is closed, the aluminum-based composite material melt obtained above is poured, and the mold is pressurized and die-casted until the extrusion pressure reaches 110 M The highest pressure in Pa, maintain the highest die-casting pressure for 5 seconds, and wait until the composite material casting is completely solidified to obtain the product triangular bracket A2. After die-casting, the product A2 is subjected to T6 heat treatment.

Example 3

This example illustrates the preparation method of the aluminum matrix composite material and product provided by the present invention.

At 720°C, add 80 grams of industrial pure aluminum to the resistance furnace to melt the aluminum, then, under the protection of argon, and at a stirring speed of 650 rpm, mix 30 grams of KBF ₄ and 35 grams of K ₂ TiF ₆ and 24 grams of _TiO2 powder are evenly sprayed into the molten aluminum, fully mixed with the molten aluminum, then, the temperature is lowered to 565 ° C, under the protection of helium, and the reaction is carried out at a stirring speed of 650 rpm for 50 minutes, and then the stirring is stopped , and then raise the temperature to raise the temperature of the above mixture to a molten state (1550 ° C), react for 7 minutes, then add 3 grams of NaSiF ₆ and 2 grams of KCl scouring agent, and continuously feed nitrogen into the mixed melt, and stir to remove by-products , to obtain the aluminum matrix composite material precursor, continue to maintain the aluminum matrix composite material precursor in a molten state (1550 ° C), and add 3.2 grams of industrial pure Mg, 4 grams of industrial pure Mg to the molten aluminum matrix composite material precursor Pure Zn, 4 grams of Cu and 6 grams of Cr were stirred and mixed for 6 minutes to remove scum to obtain an aluminum matrix composite material.

Preheat the triangular bracket die-casting mold to 240°C, and set the die-casting process parameters. The process parameters include setting the position of two blocks at 280±30 mm, and the position of one block at 130±30 mm, and the mold opening time is 4.5±2 seconds , the ejection delay is 4.0±2 seconds, the pressurization speed is 4.0±2 turns, then the cavity is closed, the aluminum-based composite material melt obtained above is poured, and the mold is pressurized and die-casted until the extrusion pressure reaches 110 M The highest pressure in Pa is maintained at the highest die-casting pressure for 10 seconds, and the composite material casting is completely solidified to obtain the product triangle bracket A3 obtained from the aluminum-based composite material. After die-casting, the product A3 is subjected to T6 heat treatment.

Example 4

This example illustrates the preparation method of the aluminum matrix composite material and product provided by the present invention.

At 720°C, add 80 grams of industrial pure aluminum to the resistance furnace to melt the aluminum, then, under the protection of argon, and at a stirring speed of 650 rpm, mix 60 grams of KBF ₄ and 56 grams of K ₂ TiF ₆ and 28 grams of TiO ₂ powder are evenly sprayed into the molten aluminum, fully mixed with the molten aluminum, then, the temperature is lowered to 565 ° C, under the protection of argon, and reacted at a stirring speed of 650 rpm for 15 minutes and then the stirring is stopped , and then raise the temperature to raise the temperature of the above mixture to a molten state (1700 ° C), react for 10 minutes, then add 6 grams of Na ₃ AlF ₆ scouring agent, and continuously feed nitrogen into the mixed melt, and stir to remove by-products to obtain aluminum Base composite material precursor, this aluminum matrix composite material precursor continues to be maintained in molten state (1700 ℃), and in the aluminum matrix composite material precursor of this molten state, add 4.8 grams of industrial pure Mg, 7 grams of Cu and 8 grams Cr, stirred and mixed for 7 minutes to remove scum and obtain an aluminum matrix composite material.

Preheat the die-casting mold of the triangular bracket to 260°C, and set the die-casting process parameters. The process parameters include setting the position of two blocks at 280±30 mm, the position of one block at 130±30 mm, and the mold opening time at 4.5±2 seconds , the ejection delay is 4.0±2 seconds, the pressurization speed is 4.0±2 turns, then the cavity is closed, the aluminum-based composite material melt obtained above is poured, and the mold is pressurized and die-casted until the extrusion pressure reaches 110 M The highest pressure in Pa is maintained for 15 seconds at the highest die-casting pressure, and the composite material casting is completely solidified to obtain the product triangle bracket A4 obtained from the aluminum-based composite material. After die-casting, product A4 is subjected to T6 heat treatment.

Comparative example 1

This comparative example illustrates the preparation of prior art aluminum matrix composites and articles.

The aluminum-based composite material was prepared according to the method disclosed in Example 1 of CN1740354A, and the above-mentioned aluminum-based composite material was die-cast according to the die-casting parameters in the method of Example 1 of the present invention to obtain the reference product triangle bracket B1. After die-casting, product B1 is subjected to T6 heat treatment.

Example 5-8

The following examples illustrate the properties of the articles provided by the present invention.

The product A1-A4 prepared by embodiment 1-4 is carried out each performance test, and test method is as follows:

The national standard GBT228 was used to measure the tensile strength, yield strength, elongation at break and elastic modulus of the product on a universal material testing machine (New Sansi Metrology Technology Co., Ltd., CMT5205). The test results are shown in Table 1 below.

Comparative example 2

This comparative example illustrates the performance of articles provided by the prior art.

Carry out various performance tests to the product B1 prepared in comparative example 1, the test method is as follows:

The national standard GBT228 was used to measure the tensile strength, yield strength, elongation at break and elastic modulus of the product on a universal material testing machine (Xin Sansi Metrology Technology Co., Ltd., CMT5205). The test results are shown in Table 1 below.

Table 1

Example number Product number Tensile strength (MPa) Yield strength (MPa) Elongation at break (%) Elastic modulus (GPa) Example 5 A1 362 311 3.7 89 Example 6 A2 421 373 5.1 102 Example 7 A3 493 418 5.6 113 Example 8 A4 495 413 5.5 115 Comparative example 2 B1 352 303 3.3 82

It can be seen from the above table 1 that compared with the product B1 obtained by die-casting the aluminum-based composite material in the prior art, the tensile strength of the products A1-A4 obtained by die-casting the aluminum-based composite material of the present invention is increased by 2.8-40.6% , The yield strength increased by 2.6-37.9%, the elongation at break increased by 12.1-69.6%, and the modulus of elasticity increased by 8.5-40.2%. It can be seen that the mechanical properties of the products made of the aluminum-based composite material obtained by the method of the present invention are good and have been significantly improved, especially the mechanical properties of the products obtained after high-pressure die-casting are even more excellent.

Claims (8)

1. A method for preparing an aluminum-based composite material, characterized in that the method comprises uniformly mixing molten aluminum with KBF ₄ , K ₂ TiF ₆ and TiO ₂ to obtain a mixture, then cooling down to 500-600°C for reaction, and then Raise the temperature to continue the reaction of the above-mentioned mixture to a molten state, remove by-products, obtain an aluminum-based composite material precursor, maintain the aluminum-based composite material precursor in a molten state, and mix the molten aluminum-based composite material precursor with magnesium Mix with copper. 2. The method according to claim 1, wherein the method of mixing aluminum with KBF ₄ , K ₂ TiF ₆ and TiO ₂ comprises stirring KBF ₄ , K ₂ TiF ₆ and TiO ₂ powders uniformly Injection into molten aluminum. 3. The method of claim 1, wherein the mixing of molten aluminum with _{KBF4 , K2TiF6} and _TiO2 is performed in an inert gas. 4. The method according to claim 1, wherein the feed weight ratio of aluminum to KBF ₄ , K ₂ TiF ₆ and TiO ₂ is 1:0.03-1.2:0.03-1.2:0.1-0.4. 5. The method according to claim 1, wherein the feed weight ratio of aluminum, magnesium and copper is 1:0.01-0.08:0.02-1. 6. The method of claim 1, further comprising mixing the molten aluminum matrix composite precursor with zinc and chromium. 7. The method according to claim 6, wherein the feed weight ratio of aluminum, zinc and chromium is 1:0-0.2:0-0.2. 8. The method according to claim 1, wherein the method for removing by-products comprises adding aluminum with KBF ₄ , K ₂ TiF ₆ and TiO before mixing the obtained aluminum matrix composite material precursor with magnesium and copper ₂ , add scouring agent and/or pass inert gas into the mixed melt.