KR101228024B1 - Fabrication method of aluminum matrix composites and aluminum matrix composite by the same - Google Patents

Abstract

An object of the present invention is to provide a method for stably producing an aluminum composite reinforced with titanium carbide and alumina while maintaining the temperature of the molten aluminum below 950 ° C.
According to one aspect of the invention, preparing a precursor mixed with aluminum powder, titanium oxide powder, carbon powder and the activating material; Adding the precursor to the molten aluminum; And casting the molten aluminum is provided.

Description

Fabrication method of aluminum matrix composites and aluminum matrix composites produced thereby {Fabrication method of aluminum matrix composites and aluminum matrix composite by the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum matrix composite material that improves mechanical properties by distributing nonmetallic materials, such as oxides or carbides, onto an aluminum matrix as a reinforcing phase (or reinforcing material), and more particularly titanium carbide (TiC) as a major reinforcing phase. And it relates to a method for producing an aluminum matrix composite material produced by alumina (Al ₂ O ₃ ) and an aluminum matrix composite material produced thereby.

Aluminum base composites are non-metallic materials such as oxides or carbides in a reinforced phase in a base made of pure aluminum or aluminum alloy, and are light weight, high strength and rigidity, excellent wear resistance and high temperature characteristics. It is expected to be used for industrial materials, electrical and electronic materials. The mechanical properties of metal matrix composites are strongly influenced by the kind, size, shape, volume fraction, and interface properties of the reinforcements to be added. In case of manufacturing composite material by injecting ceramic reinforcement into liquid base metal from outside, it is not easy to inject ceramic reinforcement into molten metal due to low wettability between ceramic reinforcement and base metal. Occurrence of interfacial reactions or low interfacial bond strengths of matrix / reinforcements may cause mechanical properties of the material to degrade. In order to overcome these problems, the research on the process of spontaneously generating the reinforcing phase inside the molten metal is being actively conducted. The reinforcing phase produced by the spontaneous reaction in the molten metal is thermodynamically stable and the interface bonding force of the matrix is enhanced because the interface of the reinforcing phase is clean. For this reason, the mechanical properties of the metal-based composite material produced using the spontaneous reaction have excellent mechanical properties compared to the composite material manufactured by the process of injecting the reinforcement from the outside.

Titanium carbide (TiC) and alumina are expected to be able to significantly increase the strength, stiffness, high temperature strength, abrasion resistance, etc. of the materials when they are distributed in an aluminum alloy due to their high hardness and elastic modulus and excellent high temperature properties. For this reason, various attempts have been made to produce titanium carbide and alumina particles by a process using a spontaneous reaction.

However, the composite material spontaneously producing titanium carbide and alumina particles in the existing aluminum molten metal has been reported to react when the aluminum molten metal is heated to 1000 ° C. or higher at the time of manufacture. Keeping the temperature of the aluminum melt as low as possible is advantageous for the production of the material. This is because evaporation of additional elements in the aluminum melt is likely to occur when the temperature of the molten metal is high as well as in terms of the apparatus, and the hydrogen concentration which decreases the characteristics of the aluminum alloy increases.

The present invention solves the problems of the prior art as described above, it is an object of the present invention to provide a method for stably producing an aluminum composite reinforced with titanium carbide and alumina while maintaining the temperature of the aluminum molten metal below 950 ℃. However, these problems are exemplary and do not limit the scope of the present invention.

According to one aspect of the invention, preparing a precursor mixed with aluminum powder, titanium oxide powder, carbon powder and the activating material; Adding the precursor to the molten aluminum; And casting the molten aluminum is provided.

 In this case, the activating material may be, for example, a material causing an exothermic reaction with any one or more of the powders. For example, the activating material may be an exothermic reaction with aluminum, and the activating material may include any one of copper oxide, cobalt oxide, manganese oxide, nickel oxide, iron oxide, vanadium oxide, chromium oxide, and tungsten oxide. can do.

In this case, the activating material may have a range of 3 wt% to 40 wt% in the precursor.

As another example of the activating material may be a material for promoting the decomposition of the titanium oxide.

In addition, the activating material may further include a material for promoting the decomposition of the titanium oxide in any one or more of the powder exothermic reaction.

The material for promoting the decomposition of the titanium oxide may include an alkali metal, alkaline earth metal or oxides of the metals, for example, may include barium, calcium, strontium, potassium and any one of these oxides. The activating material may have a range of 5 wt% or less (greater than 0) in the precursor.

On the other hand, the temperature of the molten metal may have a range of less than 950 ℃ above the melting point of aluminum.

In addition, the precursor may include pellets prepared by molding under mechanical pressure or crushed pellets.

In addition, the manufacturing method of the aluminum matrix composite material may further comprise the step of applying a plastic working to any one or more of the powder.

In addition, the aluminum molten metal may include pure aluminum molten metal or an aluminum alloy molten metal including one or more alloying elements. At this time, the alloy element is magnesium (Mg), silicon (Si), copper (Cu), manganese (Mn), chromium (Cr), zinc (Zn), nickel (Ni), iron (Fe), tin (Sn) or It may include lithium (Li).

According to another aspect of the invention, preparing a precursor mixed with aluminum powder, titanium oxide powder and carbon powder; Adding the precursor to the molten aluminum; And casting the molten metal, wherein any one or more of the powders is subjected to plastic working.

According to another aspect of the invention, the step of melting the aluminum matrix composite material prepared by the above-described manufacturing method to form a molten metal; Adding an alloying element to the molten metal; And casting the molten metal, an aluminum matrix composite material manufacturing method is provided.

According to another aspect of the invention, the aluminum base; And alumina and titanium carbide particles distributed on the aluminum matrix, wherein the alumina and titanium carbide particles are formed from a precursor mixed with aluminum powder, titanium oxide powder, carbon powder, and an activating material. Is provided.

According to another aspect of the invention, the aluminum base; Alumina and titanium carbide particles distributed on the aluminum matrix; wherein the alumina and titanium carbide are formed from a precursor mixed with aluminum powder, titanium oxide powder, and carbon powder, and the aluminum powder, titanium oxide powder, and carbon powder Any one or more of them is provided with an aluminum matrix composite, which is subjected to plastic working.

The method for manufacturing an aluminum matrix composite material according to the embodiments of the present invention enables reaction synthesis at a lower melt temperature than the conventional manufacturing method, and accelerates the reaction to shorten the manufacturing process time. Of course, the scope of the present invention is not limited by these effects.

1 is a result of calculating the thermal insulation temperature, A is the thermal insulation temperature according to the reaction formula 1, B is the thermal insulation temperature according to the reaction formula 2, C is a case where the copper oxide is added, the thermal insulation temperature according to the reaction formula 1 is calculated It is.
Figure 2 is a result of observing the microstructure of the aluminum matrix composite prepared in accordance with an embodiment of the present invention.
Figure 3 shows the X-ray diffraction analysis of the aluminum matrix composite prepared according to an embodiment of the present invention.
Figure 4 shows the X-ray diffraction analysis of the aluminum matrix composite prepared according to the comparative example.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, Is provided to fully inform the user. Also, for convenience of explanation, the components may be exaggerated or reduced in size.

In the present specification and claims, both molten pure aluminum or molten aluminum alloy containing at least one alloying element is referred to as aluminum molten metal.

According to a manufacturing method according to one embodiment of the invention, firstly a precursor for forming a reinforcing phase to be distributed in an aluminum matrix is provided. Here, the precursor refers to a mixture of reactants capable of reacting with each other in the molten aluminum to produce titanium carbide and alumina. In this case, the precursor may be a mixture in which aluminum powder, titanium oxide powder, and carbon powder are mixed.

 Titanium carbide and alumina are produced between aluminum, titanium oxide and carbon through a reaction as in Scheme 1 below.

4Al + 3TiO ₂ + 3C → 2Al ₂ O ₃ + 3TiC [Scheme 1]

At this time, the reaction is exothermic, and once the reaction starts, the reaction occurs spontaneously. In the case of the autogenous combustion reaction using the spontaneous reaction, the reaction propagates spontaneously by the heat of reaction generated by the self reaction. Therefore, when a precursor consisting of aluminum, titanium oxide and carbon is added to the molten aluminum of high temperature, the reaction of Scheme 1 spontaneously occurs to produce alumina and titanium carbide. At this time, in order to induce the spontaneous reaction of Scheme 1, the temperature of the molten metal should be maintained at 1000 ° C or higher.

In the casting of aluminum, it is advantageous to keep the temperature of the molten aluminum as low as possible in terms of production of the material. That is, in order to maintain the temperature of the molten metal at a high temperature of 1000 ° C. or more, an additional device for supplying high energy is required. In addition, the alloying element added in the molten metal is likely to evaporate while the molten metal is maintained, and the hydrogen concentration which decreases the characteristics of the aluminum alloy may be increased.

In order to reduce the temperature of the aluminum molten metal, the precursor may further include an activating material for promoting a reaction between the powders.

Here, the activating material may be, for example, causing an exothermic reaction with any one or more of the powders. Such an activating material may generate heat of reaction through reaction with any one or more of the powders to supply heat for reaction in addition to the heat of reaction generated by Scheme 1.

The activating material may be a material that reacts with aluminum to cause an exothermic reaction, and the material may include any one of copper oxide, cobalt oxide, manganese oxide, nickel oxide, iron oxide, vanadium oxide, chromium oxide, and tungsten oxide. have.

For example, copper oxide reacts with aluminum to generate large heat of reaction as in Scheme 2.

2Al + 3CuO → Al ₂ O ₃ + 3Cu [Scheme 2]

Figure 1 shows the results of calculating the adiabatic temperature due to heat generated by the reactions of Schemes 1 and 2, respectively. 1A is a heat insulation temperature value of Scheme 1, B is a heat insulation temperature value of Scheme 2. Referring to A and B of FIG. 1, the heat insulation temperature according to Scheme 1 is about 2368K, while the heat insulation temperature according to Scheme 2 reaches 3044K. Therefore, the reaction of Scheme 1 may be promoted by the amount of heat generated by Scheme 2, and correspondingly, the minimum temperature of the aluminum molten metal for allowing Scheme 1 to spontaneously react can be reduced.

1C shows the result of calculating the adiabatic temperature of Scheme 1 when copper oxide is added. Referring to this, it can be seen that the adiabatic temperature increases to 2833K. This increase in adiabatic temperature means that the temperature of the molten metal for producing the reaction scheme 1 is reduced by that much.

As another example, in the case of nickel oxide, the thermal insulation temperature was 3183K when reacting with aluminum, and 3133K in the case of iron oxide, and the same effect as copper oxide may be obtained.

On the other hand, as another example of the activation material, it may be a material that promotes the decomposition of the titanium oxide forming the precursor. That is, in the reaction of Scheme 1, titanium oxide is decomposed, and the titanium (Ti) produced therefrom is dissolved in aluminum forming the precursor and then reacts with carbon to produce titanium carbide. Therefore, when promoting the decomposition of titanium oxide, the reaction of Scheme 1 can be promoted.

Such activating material may be an element belonging to an alkali metal or alkaline earth metal of the periodic table or an oxide of such an element. For example, such an activation material may include barium (Ba), calcium (Ca), strontium (Sr), potassium (K) and oxides thereof.

As another example for promoting the reaction between the powders constituting the precursor, any one or more of the powders constituting the precursor added to the molten aluminum may be subjected to plastic working.

For example, by adding aluminum powder, titanium oxide powder and carbon powder to a device capable of applying plastic working to a powder such as a ball mill, and then mechanically plastic working on the above powders for a predetermined time, Each of the powders can be energetically activated. As such, precursors injected into the molten aluminum may be manufactured by mixing the powders subjected to the plastic working process and then molding the powders into pellets.

According to this method, as the activation of the powders is performed by plastic working, the reaction of Scheme 1 is promoted, and as a result, Scheme 1 can occur spontaneously even at a lower molten aluminum temperature.

Methods of promoting the reaction of the powders constituting the precursors exemplified as above may be applied in combination of two or more selectively with each other. For example, an activating material for exothermic reaction with aluminum and an activating material for promoting decomposition of titanium oxide may be added together. Alternatively, any one or more of the above activating materials may be mixed with aluminum powder, titanium oxide powder, and carbon powder, and then subjected to plastic processing to prepare a precursor.

At this time, the composition ratio of the activating material added to improve the thermal insulation temperature through the reaction with aluminum may be added in the range of 3% by weight to 40% by weight in the precursor. If the 3% by weight or less, the effect of the thermal insulation temperature increase is insignificant, and in more than 40% by weight may affect the casting properties of the aluminum molten metal or the properties of the aluminum matrix. For example, in the case of copper oxide, aluminum is reduced to copper (Cu), and when the reduced copper is present in a large amount of aluminum, the castability of the molten metal may be reduced.

In addition, the activating material added to promote the decomposition of the titanium oxide may be added up to 5% by weight in the precursor. If this material is added in excess of 5% by weight, it may remain in the aluminum molten metal and may adversely affect the viscosity of the molten metal. On the other hand, these elements can also obtain an effect of improving (micronizing) silicon in the process of the composite material based on the aluminum-silicon alloy to which silicon (Si) is added.

In this way, the precursors prepared by adding the activating material or applying plastic processing may be formed into pellets by the above-described method. In this case, the pellets may be directly added to the molten aluminum or may be crushed into a predetermined size. The precursor is added to the molten aluminum, held for a predetermined time, and then cast, thereby manufacturing an aluminum matrix composite material in which titanium carbide and alumina are distributed in a reinforced phase. At this time, it is possible to maintain the temperature of the molten metal at a temperature of 950 ° C or lower.

The molten aluminum may be prepared by dissolving pure aluminum or adding at least one alloying element to pure aluminum. Alloy elements that can be added are magnesium (Mg), silicon (Si), copper (Cu), manganese (Mn), chromium (Cr), zinc (Zn), nickel (Ni), iron (Fe), tin (Sn) ) And lithium (Li).

Meanwhile, the aluminum matrix composite material (first aluminum matrix composite material) prepared by the embodiments of the present invention is redissolved again to form a molten metal, and the aluminum matrix composite material is then cast by adding the aforementioned alloying elements. (Second aluminum matrix composite material) can be produced. For example, the first aluminum base composite may include titanium carbide and alumina as a reinforcing phase in a pure aluminum base, and after re-melting, selecting an appropriate alloying element and adding the alloy in consideration of the purpose of the use or alloy design. A second aluminum matrix composite material can be produced that meets the characteristics.

Hereinafter, experimental examples are provided to help the understanding of the present invention. It should be understood, however, that the following examples are for the purpose of promoting understanding of the present invention and are not intended to limit the scope of the present invention.

Table 1 shows the composition of the precursor used to prepare the aluminum matrix composites of the Experimental and Comparative Examples and the temperatures of the molten metal held during the reaction.

Psalter Molten metal Composition of the pellets (% by weight) Molten Temperature
() Reaction CuO TiO ₂ C CaO SrO ₂ Al Experimental Example 1 Pure aluminum 31.3 31.7 4.8 0 0 honey. 850 reaction Experimental Example 2 Pure aluminum 22.2 33.7 5.0 0 0 honey. 900 reaction Experimental Example 3 Pure aluminum 21.1 42.7 6.4 1.0 0 honey. 900 reaction Experimental Example 4 Pure aluminum 21.1 42.7 6.4 0 1.1 honey. 900 reaction Experimental Example 5 A356 31.3 31.7 4.8 0 0 honey. 880 reaction Experimental Example 6 A6061 31.3 31.7 4.8 0 0 honey. 880 reaction Comparative example Pure aluminum 0 58.4 8.8 0 0 honey. 930 Unreacted

The precursors of Experimental Examples 1, 2, 5 and 6 were prepared by adding copper oxide powder to aluminum powder, titanium oxide powder and carbon powder. Experimental Example 3 further added calcium oxide to the above powders, and Experimental Example 4 further added strontium oxide.

In addition, the molten metal of Experimental Examples 1 to 4 was formed by cutting pure aluminum ingot and completely dissolving it in a melting furnace. Experimental Examples 5 and 6 formed molten metal using A356 alloy and A6061 alloy, which are commercial aluminum alloys, respectively.

On the other hand, the comparative example for comparison with the above experimental example was prepared by adding a precursor consisting of aluminum powder, titanium oxide powder and carbon powder in pure aluminum molten metal.

The above experimental example and the comparative example were injected into the molten pellet precursor prepared by press-molding the mixed powder into the molten metal, after confirming that the injected pellet was exhausted by completely reacting, stirred with a graphite rod and cast in a mold mold It was prepared by.

Referring to Table 1, Experimental Example 1 to Experimental Example 6 was confirmed that all of the titanium carbide and alumina were produced at a temperature of the molten metal below 900 ℃. 2 is a result of observing the microstructure of Experimental Example 1, it was found that the fine titanium carbide and alumina particles (black portion) was formed at the base, which can be confirmed through the X-ray diffraction analysis of FIG. .

On the contrary, in the comparative example, even after the precursor was added to the molten metal maintained at 930 ° C., the reaction did not occur even after maintaining for 10 minutes or more. Even after X-ray diffraction analysis, the diffraction peaks of titanium carbide or alumina could not be found (FIG. 4). From the comparative example, it was confirmed that the aluminum composite reinforced with titanium carbide and alumina was not produced at a melting temperature of 950 ° C. or less.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (19)

Preparing a precursor mixed with aluminum powder, titanium oxide powder, carbon powder, and an activating material which is a material causing an exothermic reaction with any one or more of the powders;
Adding the precursor to the molten aluminum; And
Casting the molten aluminum;
Including, aluminum base composite manufacturing method. delete The method of claim 1, wherein the activating material is a material causing an exothermic reaction with aluminum. The method of claim 3, wherein the activating material comprises any one of copper oxide, cobalt oxide, manganese oxide, nickel oxide, iron oxide, vanadium oxide, chromium oxide, and tungsten oxide. The method of claim 3, wherein the activating material has a range of 3 wt% to 40 wt% in the precursor. The method of claim 1, wherein the activating material is a material that promotes decomposition of the titanium oxide. delete The method of claim 6, wherein the activating material comprises an alkali metal, an alkaline earth metal or an oxide of the metals. The method of claim 8, wherein the activating material comprises barium, calcium, strontium, potassium, and oxides of any of these. The method of claim 6, wherein the activating material has a range of 5 wt% or less (greater than 0) in the precursor. The aluminum matrix composite material manufacturing method according to claim 1, wherein the molten metal has a melting point of aluminum and a range of 950 ° C or less. The method according to claim 1, wherein the precursor comprises pellets prepared by molding under mechanical pressure or crushed pellets. The method of claim 1, further comprising applying a plastic working to at least one of the powders. The method of claim 1, wherein the molten aluminum comprises pure aluminum molten metal or an aluminum alloy molten metal containing at least one alloying element. The method of claim 14, wherein the alloying elements are magnesium (Mg), silicon (Si), copper (Cu), manganese (Mn), chromium (Cr), zinc (Zn), nickel (Ni), iron (Fe), A method for producing an aluminum matrix composite, comprising tin (Sn) or lithium (Li). Preparing a precursor mixed with aluminum powder, titanium oxide powder and carbon powder;
Adding the precursor to the molten aluminum; And
Casting the molten metal;
It includes, wherein any one or more of the powder is subjected to plastic processing, aluminum matrix composite material manufacturing method. Forming a molten metal by melting the aluminum matrix composite material prepared by the method of claim 1 or 16;
Adding an alloying element to the molten metal; And
And casting the molten metal. Aluminum base; And
And alumina and titanium carbide particles distributed on the aluminum matrix.
Wherein the alumina and titanium carbide particles are formed from a precursor mixed with aluminum powder, titanium oxide powder, carbon powder and an activating material which is a substance causing an exothermic reaction with any one or more of the powder. Aluminum base;
Alumina and titanium carbide particles distributed on the aluminum matrix; wherein the alumina and titanium carbide are formed from a precursor mixed with aluminum powder, titanium oxide powder, and carbon powder, and the aluminum powder, titanium oxide powder, and carbon powder At least one of the aluminum matrix composite material, which is approved for plastic processing.

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