WO2012161485A2 - Magnesium-based alloy produced using a silicon compound and a calcium compound and method for producing same - Google Patents

Abstract

The present invention relates to a magnesium-based alloy produced by adding a silicon compound and a calcium compound directly to molten magnesium or a molten magnesium alloy. The present invention also relates to a method for producing the magnesium-based alloy. More particularly, the silicon compound and the calcium compound are injected into the molten magnesium or molten magnesium alloy so as to induce a reduction reaction between said molten materials and said two compounds (the silicon compound and the calcium compound). The present invention also relates to a magnesium alloy and to a method for producing same, in which the silicon and the calcium produced by said reduction reaction are converted to an intermetallic compound in said molten materials simultaneously with said reduction reaction. The method for producing a magnesium-based alloy comprises the steps of: melting magnesium or a magnesium alloy into a liquid state; adding a silicon compound and a calcium compound to said molten magnesium or said molten magnesium alloy; removing oxygen from said silicon compound and said calcium compound through a reduction reaction between said molten materials and said compounds; and combining the silicon and calcium produced by said reduction reaction in said molten materials.

Description

Magnesium-based alloy prepared using silicon compound and calcium compound and method

The present invention relates to a magnesium-based alloy prepared by directly adding a silicon compound and a calcium compound to a molten magnesium or magnesium alloy, and a method of manufacturing the same. More specifically, a magnesium alloy and a method for preparing the same, in which a silicon compound and a calcium compound are added to a molten magnesium or magnesium alloy to induce a reduction reaction of the compound, and the silicon and calcium produced by the reduction reaction are compounded in the molten metal. It is about.

In general, magnesium or magnesium alloy is the lightest metal among practical metals, and is used as a light weight structural material due to its excellent strength and specific rigidity. In general, magnesium alloys are alloyed by adding alloying elements other than compounds to magnesium or magnesium alloys.

An object of the present invention is to provide a magnesium-based alloy prepared by a new method and a method for producing the same by adding a silicon compound and a calcium compound to the magnesium or magnesium alloy molten metal.

Another object of the present invention is to replace the silicon (Si) or calcium (Ca) added to the existing magnesium or magnesium alloy magnesium alloy that can reduce the manufacturing cost by using a low-cost silicon compound and calcium compound and its manufacture To provide a method.

Another object of the present invention is to maximize the effect of the additive alloy element by minimizing the solid solution of the silicon and calcium produced in the magnesium alloy by indirectly adding the silicon compound and the calcium compound, instead of adding silicon and calcium directly. .

Another object of the present invention is to indirectly add calcium in the form of a calcium compound to avoid a decrease in melt flow due to the direct addition of calcium, and to prevent mold sintering and hot cracking due to the direct addition of calcium.

Another object of the present invention is to maximize the amount of the compound produced by the addition of silicon and calcium elements in magnesium or magnesium alloy, induce the formation of various compounds to refine the structure of the magnesium alloy and improve the strength.

Technical problems to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned above may be clearly understood by those skilled in the art from the following description. There will be.

Magnesium-based alloy production method of the present invention for achieving the above object is the step of dissolving magnesium or magnesium alloy in the liquid phase, adding a silicon compound and calcium compound to the molten magnesium or magnesium alloy is dissolved, the molten metal and the Exhausting at least a portion of the silicon compound and the calcium compound in the magnesium or magnesium alloy through a reaction of the compound, and reacting at least a portion of the silicon and calcium resulting from the exhaustion in the magnesium or magnesium alloy. Steps.

Magnesium-based alloy manufacturing method of the present invention comprises the steps of dissolving magnesium or magnesium alloy in the liquid phase, adding a silicon compound and calcium compound to the molten magnesium or magnesium alloy is dissolved, the molten metal and the silicon compound and calcium compound Through sufficient reaction, exhausting the silicon compound and the calcium compound so that they do not remain substantially in the magnesium alloy, and reacting the silicon and calcium resulting from the exhaustion so that they do not substantially remain in the magnesium or magnesium alloy. Include.

The adding step is characterized in that the addition of the silicon compound after the addition of the silicon compound, or the addition of the silicon compound after the addition of the calcium compound.

The adding step is characterized by adding a mixture of a silicon compound and a calcium compound.

The silicon compound and the calcium compound are characterized in that the powder state to promote the reaction with the magnesium or magnesium alloy.

The silicon compound and the calcium compound are sufficiently reacted with the molten metal of the magnesium or magnesium alloy and are used up to an amount that is not exhausted and does not remain in the molten metal.

The silicon and calcium produced as a result of the exhaustion are compounded with at least one of magnesium, aluminum, and other alloying elements in the magnesium alloy, or compounded between the silicon and calcium produced so that there is substantially no residual.

The method may further include spreading the silicon compound and the calcium compound on the surface of the molten metal so as not to be mixed into the molten metal.

Oxygen elements of the silicon compound and the calcium compound are removed in the form of oxygen gas or in the form of dross through the combination of the magnesium element in the molten metal and / or the alloying element of the magnesium alloy.

The reaction of the molten metal, the silicon compound and the calcium compound is characterized by promoting the stirring of the molten metal.

The silicon compound and the calcium compound are characterized in that the particle size of 0.1 to 200㎛.

The amount of the mixture of the silicon compound and the calcium compound may be added in an amount of 0.001% by weight to 35% by weight.

The stirring is characterized in that the molten metal is made through electromagnetic stirring, or the molten metal is mechanically stirred.

The stirring may be performed in a state in which the molten surface is exposed to the atmosphere.

The compound between silicon and magnesium is Mg ₂ Si, the compound between magnesium and calcium is Mg ₂ Ca, the compound between aluminum and calcium is Al ₂ Ca, and the compound between silicon and calcium is CaSi.

The compound of silicon and magnesium is Mg ₂ Si, the compound between magnesium and calcium is Mg ₂ Ca, the compound of aluminum and calcium is Al ₂ Ca, and the compound of silicon and calcium is CaSi.

Magnesium-based alloy production method of the present invention comprises the steps of dissolving magnesium or magnesium alloy in the liquid phase, adding a silicon compound and calcium compound to the molten magnesium or magnesium alloy is dissolved, through the reduction reaction of the molten metal and the compound And removing oxygen elements of the silicon compound and the calcium compound, and compounding silicon and calcium produced by the reduction reaction in the molten metal.

The oxygen element may be removed in the form of oxygen gas or in the form of dross through bonding with magnesium in the molten metal.

The oxygen element is characterized in that the oxygen component is substantially removed over the surface of the molten metal by stirring the upper layer of the molten metal.

Silicon and calcium produced through the reduction reaction are compounded with at least one of magnesium, aluminum, and other alloying elements in the magnesium or magnesium alloy, or compounded between the produced silicon and calcium, and are substantially free of residual.

The compounding may include producing at least one of an Al-based intermetallic compound, a magnesium-based intermetallic compound, a calcium-based intermetallic compound, and a silicon-based intermetallic compound in the magnesium-based alloy.

The agitation may be performed at an upper layer of about 20% of the total depth of the melt from the surface of the melt, or at an upper layer of about 10% of the total depth of the melt from the surface of the melt.

The compound is characterized in that the compound of silicon and magnesium is Mg ₂ Si, the compound between magnesium and calcium is Mg ₂ Ca, the compound of aluminum and calcium is Al ₂ Ca, and the compound of silicon and calcium is CaSi.

The amount of the total compound of the silicon compound and the calcium compound may be added in an amount of 0.001% by weight to 35% by weight of the molten metal.

The compound of silicon and magnesium is Mg ₂ Si, the compound between magnesium and calcium is Mg ₂ Ca, the compound of aluminum and calcium is Al ₂ Ca, and the compound of silicon and calcium is CaSi.

Magnesium-based alloy of the present invention for achieving the above object is formed through the manufacturing method as described above.

As described above, according to the present invention, a magnesium-based alloy was prepared by adding a silicon compound and a calcium compound to a magnesium or magnesium alloy melt.

The present invention can reduce the production cost of magnesium alloy by directly adding a silicon compound and a calcium compound instead of adding silicon or calcium in the manufacture of a magnesium-based alloy.

The silicon compound added acts as a source of silicon. The silicon produced by the reduction reaction is not dissolved in the magnesium alloy, but directly forms a phase of the compound (typically Mg ₂ Si). As a result, it is possible to predict the amount of silicon to be deposited and included in the magnesium alloy through the amount of silicon in the silicon compound introduced.

This principle applies equally to calcium compounds. The added calcium compound acts as a source of calcium, and the calcium produced by the reduction reaction is not dissolved in the magnesium alloy, but directly forms a phase of the compound (typically Mg ₂ Ca, Al ₂ Ca).

The reduced silicon or calcium in the compound combines with the Mg of the molten metal and other alloying elements to form the compound, and also forms the compound (CaSi) between the reduced Si and Ca. These phase-formed compounds refine the structure of the magnesium alloy, greatly improving physical properties.

In addition, the present invention, due to the stability of the added silicon compound and calcium compound is suppressed the incorporation of impurities during the manufacturing process is excellent in the soundness of the alloy. As a result, the mechanical properties of the manufactured magnesium alloy are also improved.

1 is a flowchart illustrating a method of manufacturing a magnesium-based alloy according to the present invention.

Figure 2 is a flowchart of dissociation of the silicon compound and calcium compound added to the molten magnesium in the present invention.

3 is a structure photograph (× 50) of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to Mg according to the present invention.

4 is a structure photograph (× 100) of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to Mg according to the present invention.

5 is a structure photograph (× 200) of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to Mg according to the present invention.

6 is a graph showing an EPMA point analysis of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to Mg according to the present invention.

Figure 7 is a SEM image of the polishing surface of the magnesium alloy prepared by adding 0.3wt% SiO ₂ and 0.3wt% CaO to Mg according to the present invention.

8 is a photograph showing a mapping analysis of magnesium (Mg) of magnesium alloy prepared by adding 0.3wt% SiO ₂ and 0.3wt% CaO to Mg according to the present invention.

Figure 9 is a photograph showing the mapping analysis of calcium (Ca) of magnesium alloy prepared by adding 0.3wt% SiO ₂ and 0.3wt% CaO to Mg according to the present invention.

FIG. 10 is a photograph showing mapping analysis of silicon (Si) of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to Mg according to the present invention.

FIG. 11 is a photograph showing mapping analysis for oxygen (O) of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to Mg according to the present invention.

12 is a structure photograph (× 50) of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to an Mg alloy (AM 60) according to the present invention.

FIG. 13 is a structure photograph (× 100) of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to an Mg alloy (AM 60) according to the present invention.

14 is a structure photograph (× 200) of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to an Mg alloy (AM 60) according to the present invention.

FIG. 15 is a graph showing point analysis of EPMA of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to an Mg alloy (AM 60) according to the present invention.

16 is a photograph showing a mapping analysis of magnesium (Mg) of magnesium alloy prepared by adding 0.3wt% SiO ₂ and 0.3wt% CaO to Mg alloy (AM60) according to the present invention.

FIG. 17 is a photograph showing mapping analysis of aluminum (Al) of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to an Mg alloy (AM 60).

18 is a photograph showing a mapping analysis of calcium (Ca) of magnesium alloy prepared by adding 0.3wt% SiO ₂ and 0.3wt% CaO to Mg alloy (AM60) according to the present invention.

FIG. 19 is a photograph showing mapping analysis of silicon (Si) of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to an Mg alloy according to the present invention.

FIG. 20 is a photograph showing mapping analysis of oxygen (O) of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to an Mg alloy according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention. Like elements in the figures are denoted by the same reference numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

The present invention relates to a method for producing a new alloy by adding a silicon compound and a calcium compound to a molten magnesium or magnesium alloy and an alloy thereof.

1 is a flowchart illustrating a method of manufacturing a magnesium-based alloy according to the present invention.

As shown in FIG. 1, the method for preparing a magnesium-based alloy according to the present invention includes forming a molten magnesium (S1), adding a silicon compound and a calcium compound (S2), stirring (S3), and silicon. A step (S4) of exhausting the compound and the calcium compound, a reaction step (S5) of the molten metal and the silicon / calcium, a casting step (S6), and a solidification step (S7) are included.

The step of exhausting the silicon compound and the calcium compound (S4), the reaction step of the molten metal and silicon / calcium, and the reaction step of the silicon and calcium (S5) are separated into separate steps for convenience of description, but the two processes (S4, S5) Happens almost simultaneously. And S4 and S5 may occur substantially before the stirring step of S3. S4 and S5 can occur simultaneously with the addition of the compound.

The magnesium-based molten metal forming step (S1) is put into a furnace or crucible in magnesium or magnesium alloy to provide a temperature of 400 to 800 ℃ in a protective gas atmosphere. Then, magnesium or magnesium alloy in the crucible is dissolved to form magnesium-based molten metal.

Melting temperature of magnesium or magnesium alloy

In the present invention, the temperature for dissolving magnesium or magnesium alloy means the temperature at which the pure magnesium metal melts and the temperature at which the magnesium alloy melts. The melting temperature may vary depending on the type of alloy. For sufficient reaction, silicon compound and calcium compound are added while magnesium or magnesium alloy is completely dissolved. The melting temperature of magnesium or magnesium alloy is sufficient to be a temperature at which the solid phase is sufficiently melted and is present in a complete liquid phase. However, in view of the point that the temperature of the molten metal falls due to the addition of the compound in the present invention, it is necessary to maintain the molten metal in a sufficient temperature range. Alternatively, the silicon compound and the calcium compound may be heated to a predetermined temperature and added to the molten metal.

Here, if the temperature is less than 400 ℃ magnesium alloy molten metal is difficult to form, if the temperature exceeds 800 ℃ there is a risk that the magnesium-based molten metal is ignited. In the case of magnesium, the molten metal is generally formed at 600 ° C. or higher, but in the case of magnesium alloy, the molten metal may be formed at 400 ° C. or lower. In general, as metallization is alloyed, the melting point is often lowered.

If the melting temperature is raised too high, vaporization of the liquid metal may occur, and due to the nature of magnesium, it may easily ignite, resulting in loss of molten metal and adversely affect final properties.

Magnesium used in the magnesium-based molten metal forming step may be any one selected from pure magnesium, magnesium alloy and equivalents thereof. In addition, the magnesium alloy is AZ91D, AM20, AM30, AM50, AM60, AZ31, AS41, AS31, AS21X, AE42, AE44, AX51, AX52, AJ50X, AJ52X, AJ62X, MRI153, MRI230, AM-HP2, Magnesium-Al, Magnesium-Al-Re, magnesium-Al-Sn, magnesium-Zn-Sn, magnesium-Si, magnesium-Zn-Y and the equivalent may be any one selected from, but the magnesium alloy is not limited to the present invention. Typically, any magnesium alloy used in the industry can be used.

In the adding of the silicon compound and the calcium compound (S2), the silicon compound and the calcium compound may be added to the magnesium molten metal. The method of adding the compound may be one of 1) adding a silicon compound after adding a silicon compound, 2) adding a silicon compound after adding a calcium compound, or 3) simultaneously adding a mixture of the two compounds. Here, the compound is preferably in a powder state in order to promote the reaction with the magnesium alloy.

Powder state of silicon compound and calcium compound

The silicon compound and calcium compound added for the reaction may be added in any form. It is preferable to add powder in order to increase the reaction surface area for efficient reaction. However, if it is too fine, less than 0.1㎛ it is difficult to be injected into the furnace is scattered by the evaporated magnesium or hot air. Then, they coagulate with each other and become agglomerated without easily mixing with the molten metal in the liquid phase. If too thick, as mentioned, it is not preferable from the viewpoint of increasing the surface area. It is preferable that the particle size of an ideal powder shall be 500 micrometers or less. More preferably, it is 200 micrometers or less.

However, in order to prevent the scattering of the powder phases, it is also possible to add a compound in the form of agglomerated powder.

Input compound (silicon compound and calcium compound)

As the silicon compound added to the molten metal, SiO ₂ may be typically used. And CaO may be used as the calcium compound. Here, not only SiO ₂ and CaO but any kind of silicon compound or calcium compound may be used.

The total amount of the two compounds used in the addition step of the silicon compound and the calcium compound depends on the amount of magnesium or magnesium molten metal. The amount of the compound that can be added by reaction in the molten metal may be added up to an amount that does not remain as a silicon compound in the molten metal and the final magnesium alloy by exhausting all of the silicon compound injected by sufficiently reacting with magnesium or magnesium alloy molten metal. If an amount of compound in excess of the possible reaction is introduced, it is removed after tapping together with the dross of the molten metal. Through experiments, it was found that when the compound was added up to 35% by weight of the molten metal, the mixed compound was easily reduced in the molten metal. If the minimum value was less than 0.001% by weight, the effect of adding the compound was insignificant.

The input amount of the silicon compound is determined according to the final target alloy composition desired. In other words, the amount of silicon compound can be determined by inversely calculating the amount of silicon alloyed in the magnesium alloy. The same principle applies to calcium compounds.

Two compounds added in the compounding step may be added in the form of a mixture. It is also possible to add one compound first, followed by another with a time difference.

In the stirring step (S3) it is stirred for 1 second to 60 minutes per 0.1wt% of the two compounds added to the magnesium or magnesium alloy molten metal.

If the stirring time is less than 1 second per 0.1 wt%, the compound does not sufficiently react to the magnesium molten metal. If the stirring time exceeds 60 minutes per 0.1 wt%, the stirring time of the magnesium molten metal may be unnecessarily longer. In general, the time of stirring depends on the size of the melt and the amount of the total compound added.

Although the addition of the required amount of the compound powder may be performed at a time, the method may be used. However, in order to accelerate the reaction and lower the possibility of aggregation of the powder, it is also preferable to sequentially add the compound powder again or by dividing it in an appropriate amount with a time difference.

Weight ratio of silicon compound and calcium compound

In principle, the mixing ratio of the silicon compound and the calcium compound to be added to the molten magnesium or magnesium alloy can be varied. The total amount of compound added is 0.001% to 35% by weight based on the weight of the melt. It was also possible to easily generate a reduction reaction up to 35% by weight in the molten metal. The weight ratio of the two compounds could be varied in the range of addition of the total compounds.

Stirring Method and Conditions

Stirring is preferred for efficient reaction of the magnesium or magnesium alloy of the present invention with a silicon compound and a calcium compound. The stirring may be provided with a device for applying an electromagnetic field around the furnace containing the melt to generate an electromagnetic field to induce convection of the melt. In addition, it is possible to perform artificial stirring (mechanical stirring) on the molten metal from the outside. In the case of mechanical stirring, the compound powder to be added may be appropriately stirred so as not to agglomerate. The ultimate purpose of the agitation is to adequately induce the reaction of the melt with the injected powder.

The time for stirring may vary depending on the temperature of the molten metal and the state of the compound powder to be added (preheated state, etc.). Preferably, stirring is performed until the powder of the compound is not seen in the molten metal. It is preferable to stir until the molten metal and the compound cause a sufficient reaction. Sufficient reaction herein means a state in which the compound is exhausted by substantially all reduction reactions with the molten metal.

The specific gravity of calcium compounds (in the case of CaO) is less than that of magnesium or magnesium alloys. Therefore, the calcium compound flows on the molten metal regardless of the shape.

The specific gravity of the silicon compound (SiO ₂ ) is greater than that of magnesium or magnesium alloy. Thus, the silicon compound sinks into the molten magnesium or magnesium alloy. However, when the silicon compound is a powder, it is more likely that the viscosity viscosity of the molten metal floats on the upper portion of the molten metal without falling below the molten metal due to the magnitude of the influence of the specific gravity of the powder. As a result, in the present invention, since the compound in the form of a powder is used, it can be said that the agitation of the compound is performed in the upper portion.

It is preferable to give a time that the unreacted powder can react while having a holding time even after sufficient stirring time.

Timing of agitation

It is effective to perform the timing of stirring simultaneously with the addition of the compound powder. Stirring is continued until no powder of the compound injected into the molten metal is detected. After the exhaustion of the two compounds added, the reaction is completed and the stirring is completed.

Surface reaction

In general, in the case of alloying the metal, it is common to induce an active reaction by convection or stirring the molten metal and the alloying element metal so that the reaction occurs inside the molten metal. In this invention, such a method of convection and stirring can also be applied. In addition, while the injected compound (silicon compound and calcium compound) is introduced to the surface of the molten metal, the reaction may be promoted through stirring of the upper surface of the molten metal. That is, it is possible to maximize the reduction reaction of the silicon compound and the calcium compound by inducing a reaction on the surface of the melt rather than the reaction in the melt.

In the present invention, it is important to create a reaction environment so that the compound reacts on the surface of the melt rather than reacting in the melt. To do this, it is important not to force the compound suspended on the surface of the melt into the melt. It is important to simply spread the compound on the surface so that it spreads evenly across the surface of the melt.

It was better to do the reaction rather than to agitate, and it was better to stir on the outer surface (upper surface) than on the inside of the molten metal. That is, the outer surface (top surface) reacted better with the atmosphere and the exposed powder. In the case of calcium compounds, the contact of the molten metal with the air was better for the reduction reaction. For sufficient reaction, it is necessary to induce surface reaction by stirring the upper portion. For this purpose, it is important to cause surface agitation immediately after adding the compound to the molten metal in order to prevent the possibility of precipitation of the silicon compound. In addition, it is important not to inject excessive amounts of silicon compounds at the same time, but to inject a proper amount sequentially in consideration of the surface area of the molten metal so that the compound has many opportunities for reaction on the surface of the molten metal.

Oxygen content of the silicon compound or calcium compound is substantially removed over the surface of the melt through stirring of the upper layer of the melt. The agitation may be performed at an upper layer of about 20% of the total depth of the molten metal from the molten surface. At a depth of 20% or more, the surface reactions presented as preferred examples in the present invention are difficult to occur. More preferably, the stirring is performed at the upper layer part of about 10% of the total depth of the molten metal from the molten surface. This could minimize the disturbance of the molten metal by actually placing the floating silicon compound or calcium compound in the upper layer 10% above the depth of the molten metal.

In the exhausting step of the silicon compound and the calcium compound (S4), the silicon compound and the calcium compound are exhausted so as not to be at least partially exhausted or substantially remain in the magnesium alloy through the reaction between the molten metal and the added two compounds. Let's go. The silicon compound and calcium compound introduced in the present invention is preferably exhausted by a sufficient reduction reaction. However, it is effective even if some of the reaction remains in the alloy and does not significantly affect the physical properties.

Here, to exhaust the silicon compound and the calcium compound is to remove oxygen elements (components) from the silicon compound and the calcium compound. The oxygen element may be removed in the form of oxygen (O ₂ ) gas, or in the form of dross or sludge through bonding with magnesium or an alloy component thereof in the molten metal. The oxygen component is then removed substantially above the melt surface through stirring of the melt top layer.

In the reaction step of the molten metal and silicon / calcium and the reaction between silicon calcium (S5), the silicon and calcium produced as a result of the exhaustion of the silicon compound and the calcium compound are reacted so as not to remain at least partially or substantially in the magnesium or magnesium alloy. Let's go. Here, the silicon and calcium produced as a result of the exhaustion are compounded with at least one of magnesium, aluminum, and other alloying elements (components) in the magnesium alloy so as not to remain substantially. Here, the compound refers to an intermetallic compound formed by combining a metal and a metal. Or a compound formed by bonding a metal and a semiconductor (here, Si).

Eventually, the added silicon compound and calcium compound are removed at least partly or substantially by removing oxygen components (elements) through a reduction reaction with the molten metal, and the silicon or calcium from which the oxygen element is removed is magnesium, aluminum, and It is compounded with at least one of the other alloying elements so that it does not remain at least partially or substantially in the magnesium alloy. Silicon and calcium produced by the reduction reaction may form compounds with each other. The process described so far is illustrated in FIGS. 1 and 2. Figure 2 is a flowchart of dissociation of a mixture of a silicon compound and a calcium compound used in addition to the molten magnesium in the present invention.

On the other hand, in the casting step (S6), the magnesium molten metal is cast in a mold at room temperature or preheated state. Herein, the mold may use any one selected from a mold, a ceramic mold, a graphite mold, and an equivalent thereof. In addition, the casting method may be gravity casting, continuous casting and the equivalent method.

In the magnesium-based alloy, a compound is formed between at least one of magnesium, aluminum, and other alloy elements in the molten metal, and calcium and silicon produced. In addition, silicon and calcium produced by the reduction reaction may form compounds with each other.

In the solidification step (S7), after cooling the mold to room temperature, the magnesium alloy (eg. Magnesium alloy ingot) is taken out of the mold.

In the case of pure magnesium molten metal, the magnesium component in the molten metal reacts with silicon or calcium to form magnesium (silicon) or magnesium (calcium) compounds. When the compound is SiO ₂ , Mg ₂ Si is formed. When the compound is CaO, Mg ₂ Ca is formed. And silicon and calcium combine to form CaSi. Oxygen, which was composed of SiO ₂ or CaO, becomes O _{2 and} is discharged out of the molten metal, or combined with Mg to be MgO and discharged in the form of dross.

Scheme 1

Pure Mg + SiO ₂ + CaO-> Mg (Matrix) + Mg ₂ Si + Mg ₂ Ca + Mg (Si, Ca) + CaSi

... [O ₂ occurrence + MgO dross occurrence]

Here, silicon and calcium formed by the reduction reaction may form magnesium and a compound (Mg (Si, Ca)). In addition, a compound of CaSi may be generated instead of a compound of Mg ₂ Si or Mg ₂ Ca. CaSi compounds are more preferred in terms of high temperature strength because they have a higher melting point than other produceable compounds.

In the case of magnesium alloy molten metal, the magnesium component in the molten metal reacts with silicon or calcium to form a magnesium (silicon) compound or a compound of magnesium (calcium). In addition, silicon and / or calcium formed by the reduction reaction may form a complex compound with magnesium. In addition, instead of magnesium, aluminum may form a compound with the calcium.

In addition, alloying elements in molten metal together with magnesium or aluminum form compounds with silicon and / or calcium. In one embodiment, silicon or calcium is Mg ₂ Si, or (Mg, Al, other alloying elements) ₂ Si and / or Mg ₂ Ca, Al ₂ Ca, or (Mg, Al, other alloying elements) ₂ Ca and / or (Mg , Al, other alloying elements) ₂ (Ca, Si) are formed. And oxygen was SiO ₂ or CaO and configure is the O ₂ as in the case of pure magnesium or discharged from the molten metal, is in combination with Mg and MgO is discharged to form dross (see Reaction Formula 2 below)

Compounds that can be produced through a reduction reaction may generate CaSi as well as the above-mentioned compounds. In this case CaSi is preferred over other compounds in terms of high temperature strength because of its higher melting point than other produceable compounds.

Scheme 2

Mg Alloy + SiO ₂ + CaO-> Mg Alloy (Matrix) +

(Mg ₂ Si + Al ₂ Si + (Mg, Al, other alloying elements) Si

+ (Mg ₂ Ca + Al ₂ Ca + (Mg, Al, other alloying elements) Ca

         + (Mg, Al, other alloying elements) (Ca, Si) + CaSi

... [O ₂ occurrence + MgO dross occurrence]

As described above, the present invention can produce magnesium alloys more easily and economically than in the conventional production method of magnesium alloys. Calcium is a relatively expensive alloying element compared to calcium compounds, which acts as a factor to increase the price of magnesium alloy. In addition, it is relatively easy to alloy by adding silicon compound or calcium compound to magnesium or magnesium alloy in place of silicon or calcium. On the other hand, by adding chemically stable silicon compounds and calcium compounds without adding silicon or calcium directly, compounds that are ultimately important for the strength of magnesium alloys (eg Mg ₂ Si) and / or intermetallic compounds (Mg ₂ Ca) And CaSi and other compounds.

In addition, when silicon or calcium is directly added to magnesium or magnesium alloy, a solid solution of silicon occurs in a magnesium alloy, whereas in the present invention, the degree of solubility is directly added when adding a silicon compound or a calcium compound. There is no employment or very few in comparison with the case. Therefore, in order to increase the properties of magnesium alloy, it is necessary to add more than a certain amount of silicon or calcium, whereas when alloying with silicon compound or calcium compound, a significant amount of silicon or calcium directly forms intermetallic compounds (or compounds). This can be seen that the physical properties are improved.

The magnesium-based alloy prepared in the present invention is a casting alloy, a rutten alloy, a creep alloy, a damping alloy, a degradable bio alloy and a powder metal. It can be used with at least one selected from powder metallurgy.

Magnesium-based alloy prepared by the manufacturing method of the present invention may have a hardness (HRF) of 40 to 80. However, since these hardness values vary according to processing methods and heat treatments, the hardness values do not limit the magnesium alloy according to the present invention.

Table 1 is a table showing the hardness at room temperature of the magnesium alloy prepared in the present invention. The hardness of the magnesium alloy prepared by adding a 1: 1 (0.3 wt% SiO ₂ and 0.3 wt% CaO) amount of silicon compound and calcium compound in pure magnesium was measured.

Table 1 Psalm Number One 2 3 4 5 6 7 Average Hardness (HR15T) 39 39 42 43 43 40 41 41

Table 2 is a table showing the hardness at room temperature of the magnesium alloy prepared in the present invention. The hardness of the magnesium alloy prepared by adding a 1: 1 (0.3 wt% SiO ₂ and 0.3 wt% CaO) of silicon compound and calcium compound in a weight ratio to the magnesium alloy AM60 was measured.

TABLE 2 Psalm Number One 2 3 4 5 6 7 Average Hardness (HRF) 45 45 46 46 42 42 44 44.3

The compound was added to the mixture, or one compound was added first and then another compound was added to obtain the same or similar properties. In addition, it can be seen that the hardness and strength increase as the total amount of the two compounds in the magnesium alloy increases. If no compound is added, the hardness of Mg is about 30 HRF.

In the case of the magnesium alloy produced in the present invention appeared higher than the hardness of the same magnesium alloy. This is because the silicon produced by the reduction reaction forms compounds with Mg and / or other alloying elements in magnesium or magnesium alloys. In particular, the resulting Mg ₂ Si, Mg ₂ Ca and CaSi has a high hardness, low coefficient of thermal expansion, and a high melting point to improve the mechanical properties of the magnesium alloy.

3, 4, and 5 are tissue photographs (× 50, × 100, × 200) of magnesium alloys prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to Mg according to the present invention. When the silicon compound and the calcium compound are added to the molten magnesium or magnesium alloy, it can be confirmed that the structure of the magnesium and the magnesium alloy is refined due to the formation of the intermetallic compound by the reduction reaction.

12, 13, and 14 are tissue photographs (× 50, × 100, × 200) of magnesium alloys prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to commercial magnesium (AM60) according to the present invention. As can be seen in the tissue photographs, it was confirmed that the structure was refined by adding SiO ₂ and CaO to the molten magnesium or magnesium alloy. This is because grain growth of the microstructure is suppressed due to phase formation with silicon, magnesium, and other alloying elements generated by the reduction reaction.

FIG. 6 is a graph illustrating point analysis of EPMA of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to Mg according to the present invention. As a result of component analysis of the phase-formed point, it can be seen that magnesium-silicon-calcium compound or magnesium-silicon compound was formed by directly adding SiO ₂ and CaO to the magnesium molten metal. In the composition analysis of the point 1 and point 2, the result added to the silicon compound and the calcium compound to the magnesium molten Mg and Si, it can be seen that having a compound of Ca, Mg and Si Mg ₂ Si to a component analysis result of point 3 It can be seen that the phase formation of.

Table 3 below shows the component composition ratios of Mg, Si and Ca measured at each of points 1, 2 and 3, which are the positions of the formed phases.

TABLE 3 Mg Si Ca Total Point 1 59.24 24.96 15.80 100 Point 2 71.48 15.74 12.78 100 Point 3 92.49 7.51 - 100

FIG. 7 is a SEM photograph (BEI: Back-Scattered Electron Image) of a specimen of which the surface of the Mg alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to Mg was polished for EPMA mapping. The grain boundary can be confirmed faintly.

FIG. 8 is a photograph of EPMA (Electron Probe Micro Analyzer) mapping analysis of Mg alloy by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to Mg in pure magnesium molten metal. It can be seen that magnesium is present in almost all regions of the specimen. It can be seen that magnesium has no atoms or fewer than other regions in the phase formation region.

9 shows the presence of calcium component elements along the grain boundaries as EPMA Mapping photographs of calcium elements. The blue area (darkness in black and white) in the picture is the part without the corresponding element. In FIG. 9, it can be seen that the concentration of calcium is concentrated in the region of the phase formation region.

FIG. 10 shows the presence of silicon components along the grain boundaries as an EPMA mapping photograph of silicon elements. 9 and 10, it can be seen that the regions in which Si and Ca overlap with the regions in which Mg exists. This indirectly suggests that Mg, Si, and Ca form a compound. That is, Si and Ca separated from SiO ₂ and CaO formed a phase with Mg (or other alloying elements) without being dissolved in the Mg base.

11, it can be seen that no oxygen component is present in the Mg alloy prepared according to the present invention. This shows that O is separated from SiO ₂ and CaO added to the Mg alloy and disappears in the molten state in the form of O ₂ gas or is removed in the alloy as a dross in the form of MgO (or a compound of Al or other alloying elements).

FIG. 15 is a graph illustrating point analysis of EPMA when 0.3 wt% SiO ₂ and 0.3 wt% CaO are added to a magnesium alloy prepared according to the present invention. As a result of component analysis of the point of the image formation position, it can be seen that the magnesium-aluminum-silicon-calcium compound was formed by directly adding SiO ₂ and CaO to the magnesium alloy melt.

Table 4 below shows the component ratios of Mg, Al, Si, and Ca measured at each of points 1, 2, and 3.

Table 4 Mg Al Si Ca Total Point 1 52.15 11.11 20.15 16.59 100 Point 2 54.01 17.33 18.10 10.56 100 Point 3 52.60 6.90 21.44 19.06 100

FIG. 16 is a photograph showing mapping analysis of magnesium (Mg) of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to a commercial magnesium alloy according to the present invention. It can be seen from the photograph that magnesium is present throughout all areas of the specimen.

FIG. 17 is a photograph showing mapping analysis of aluminum (Al) of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to an Mg alloy (AM 60). As a photograph of the aluminum element, it can be seen that the aluminum elements exist mainly along the grain boundaries. In the picture, blue is the part without the corresponding element.

In FIG. 16, mapping of magnesium and mapping of aluminum of FIG. 17 overlap each other. It can be seen that Al of the Mg composite metal forms a compound with Mg.

18 is a photograph showing a mapping analysis of calcium (Ca) of magnesium alloy prepared by adding 0.3wt% SiO ₂ and 0.3wt% CaO to Mg alloy (AM60) according to the present invention.

FIG. 19 is a photograph showing mapping analysis of silicon (Si) of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to an Mg alloy according to the present invention.

The mapping of calcium and silicon of FIGS. 18 and 19 overlaps with the mapping of magnesium and aluminum of FIGS. 16 and 17. This suggests that Mg, Si, Al, and Ca form a compound. This is because Si and Ca separated from SiO ₂ and CaO formed a phase with Mg and other alloying elements Al without being dissolved in the Mg base.

FIG. 20 is a photograph showing mapping analysis of oxygen (O) of a magnesium alloy prepared by adding 0.3 wt% SiO ₂ and 0.3 wt% CaO to an Mg alloy according to the present invention. 20, it can be seen that no oxygen component is present in the alloy. This shows that oxygen is separated from SiO ₂ and CaO added to the Mg alloy and disappears in the molten state in the form of O ₂ gas or is removed in the alloy by dross in the form of MgO (or a compound of Al or other alloying elements).

It can be seen that the Al-Ca-based compound phases including Al ₂ Ca are formed by overlapping the Al and Ca regions, and that the Ca-Si-based compound including the CaSi phase is formed by the same detection region of Ca and Si.

As a result of the component analysis of each point of EPMA, it was confirmed that silicon and calcium produced by adding silicon compound and calcium compound in pure magnesium and AM60 magnesium alloy produced magnesium or its constituent elements and various kinds of intermetallic compounds. Could.

As described above, the present invention can reduce the production cost of the magnesium alloy by directly adding a silicon compound and a calcium compound, instead of adding silicon or calcium in the manufacture of the magnesium-based alloy.

The reduced silicon or calcium in the compound combines with the Mg and other alloying elements of the molten metal to form the compound, and also forms a compound (CaSi) between the reduced Si and Ca. These phased compounds refine the structure of the magnesium alloy, thereby improving the mechanical properties of the resulting magnesium alloy.

The present invention has been described with reference to the preferred embodiments, and those skilled in the art to which the present invention pertains to the detailed description of the present invention and other forms of embodiments within the essential technical scope of the present invention. Could be. Here, the essential technical scope of the present invention is shown in the claims, and all differences within the equivalent range will be construed as being included in the present invention.

Claims (32)

In the method for producing a magnesium-based alloy, Dissolving magnesium or magnesium alloy in a liquid phase; Adding a silicon compound and a calcium compound to the molten metal in which the magnesium or magnesium alloy is dissolved; Exhausting at least a portion of the silicon compound and the calcium compound in the magnesium or magnesium alloy through the reaction of the molten metal and the compound; And Reacting at least a portion of the silicon and calcium produced as a result of the exhaust in the magnesium or magnesium alloy; comprising, magnesium-based alloy manufacturing method. In the method for producing a magnesium-based alloy, Dissolving magnesium or magnesium alloy in a liquid phase; Adding a silicon compound and a calcium compound to the molten metal in which the magnesium or magnesium alloy is dissolved; Exhausting the silicon compound and the calcium compound such that the silicon compound and the calcium compound do not substantially remain in the magnesium alloy through sufficient reaction of the molten metal, the silicon compound and the calcium compound; And And reacting silicon and calcium produced as a result of the exhaustion so as not to remain substantially in the magnesium or magnesium alloy. The method of claim 2, The adding step is characterized in that the addition of the silicon compound after the addition of the silicon compound, or adding the calcium compound after the addition of the calcium compound, magnesium-based alloy manufacturing method. The method of claim 2, The adding step is characterized in that for adding a mixture of silicon compounds and calcium compounds, magnesium-based alloy manufacturing method. The method of claim 2, The silicon compound and the calcium compound is characterized in that the powder form to promote the reaction with the magnesium or magnesium alloy, magnesium-based alloy manufacturing method. The method of claim 2, And the silicon compound and the calcium compound are reacted sufficiently with the molten metal of the magnesium or magnesium alloy to be used up to an amount that is exhausted and does not remain in the molten metal. The method of claim 2, The magnesium-based alloy, which is formed as a result of the exhaustion, is compounded with at least one of magnesium, aluminum, and other alloying elements in the magnesium alloy, or compounded between the produced silicon and calcium, and is not substantially remaining. Manufacturing method. The method according to any one of claims 2 to 6, And spreading the silicon compound and the calcium compound evenly on the surface of the molten metal so as not to be mixed into the molten metal. The method according to any one of claims 2 to 6, Oxygen element of the silicon compound and the calcium compound is removed in the form of oxygen gas or in the form of dross through the combination of the magnesium element and / or the alloying element of the magnesium alloy in the molten metal, characterized in that Method of manufacturing magnesium alloy. The method according to any one of claims 2 to 6, Magnesium-based alloy production method, characterized in that to promote the reaction of the molten metal, the silicon compound and the calcium compound through the stirring of the molten metal. The method of claim 5, The silicon compound and the calcium compound is characterized in that the particle size of 0.1 to 200㎛, magnesium-based alloy manufacturing method. The method of claim 6, Magnesium-based alloy manufacturing method, characterized in that the addition amount of the mixture of the silicon compound and the calcium compound is added in 0.001% by weight to 35% by weight. The method of claim 11, The stirring is characterized in that the molten metal is made through electromagnetic stirring, magnesium-based alloy production method. The method of claim 11, The stirring is a method of producing a magnesium-based alloy, characterized in that for mechanically stirring the molten metal. The method of claim 11, The said stirring is performed in the state which the said molten metal surface was exposed to air | atmosphere, The magnesium type alloy manufacturing method characterized by the above-mentioned. The method of claim 7, wherein Mg ₂ Si, the compound between magnesium and calcium is Mg ₂ Ca, the compound between aluminum and calcium is Al ₂ Ca, and the compound between silicon and calcium is CaSi, magnesium-based alloy manufacturing method The method of claim 12, The method of producing a magnesium-based alloy, wherein the compound of silicon and magnesium is Mg ₂ Si, the compound between magnesium and calcium is Mg ₂ Ca, the compound of aluminum and calcium is Al ₂ Ca, and the compound of silicon and calcium is CaSi. In the method for producing a magnesium-based alloy, Dissolving magnesium or magnesium alloy in a liquid phase; Adding a silicon compound and a calcium compound to the molten metal in which the magnesium or magnesium alloy is dissolved; Removing oxygen elements of the silicon compound and the calcium compound through a reduction reaction of the molten metal and the compound; And Compounding the silicon and calcium produced by the reduction in the molten metal; Method comprising, magnesium-based alloy manufacturing method. The method of claim 18, The oxygen element is removed in the form of oxygen gas, or in the form of dross through the combination with magnesium in the molten metal, characterized in that the magnesium-based alloy manufacturing method. The method of claim 18, The oxygen element, characterized in that the oxygen component is substantially removed on the surface of the molten metal through the stirring of the upper layer, magnesium-based alloy manufacturing method. The method of claim 18, Silicon and calcium produced through the reduction reaction are compounded with at least one of magnesium, aluminum, and other alloying elements in the magnesium or magnesium alloy, or compounded between the produced silicon and calcium, and are not substantially left. Method of manufacturing magnesium alloy. The method of claim 18, The silicon compound and the calcium compound is characterized in that the powder form to promote the reaction of the magnesium or magnesium alloy, magnesium-based alloy manufacturing method. The method of claim 18, The compound is fully reacted with the molten metal of the magnesium or magnesium alloy is exhausted, characterized in that the input to the amount that the compound does not remain in the molten metal, magnesium-based alloy manufacturing method. The method of claim 18, The silicon compound and the calcium compound is characterized in that the particle size of 0.1 to 200㎛, magnesium-based alloy manufacturing method. The method of claim 18, Wherein the compounding step, Magnesium-based alloy, characterized in that for producing at least one of the Al-based intermetallic compound and magnesium-based intermetallic compound, calcium-based intermetallic compound, silicon-based intermetallic compound in the magnesium-based alloy Manufacturing method. The method of claim 20, The stirring is a magnesium-based alloy manufacturing method, characterized in that the stirring is performed in the upper layer portion of about 20% of the total depth of the molten metal from the molten surface. The method of claim 20, The stirring is a magnesium-based alloy manufacturing method, characterized in that the stirring is performed in the upper layer portion of about 10% of the total depth of the molten metal from the molten surface. The method of claim 20, The said stirring is performed in the state which the said molten metal surface was exposed to air | atmosphere, The magnesium type alloy manufacturing method characterized by the above-mentioned. The method of claim 21, Said compound is Mg ₂ Si compound of magnesium and magnesium, Mg ₂ Ca compound of magnesium and calcium, Al ₂ Ca of compound of aluminum and calcium, and CaSi compound of Ca and calcium is CaSi manufacturing method. The method of claim 23, The amount of the total compound of the silicon compound and the calcium compound is characterized in that the addition of 35% by weight to 0.001% by weight of the molten metal, magnesium-based alloy manufacturing method. The method of claim 25, The method of producing a magnesium-based alloy, wherein the compound of silicon and magnesium is Mg ₂ Si, the compound between magnesium and calcium is Mg ₂ Ca, the compound of aluminum and calcium is Al ₂ Ca, and the compound of silicon and calcium is CaSi. 32. The method of claim 1 Magnesium-based alloy formed by the manufacturing method of at least one claim.

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