KR101145124B1 - Melting method for magnesium alloy and manufacturing method thereof - Google Patents
Melting method for magnesium alloy and manufacturing method thereof Download PDFInfo
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- KR101145124B1 KR101145124B1 KR20100028166A KR20100028166A KR101145124B1 KR 101145124 B1 KR101145124 B1 KR 101145124B1 KR 20100028166 A KR20100028166 A KR 20100028166A KR 20100028166 A KR20100028166 A KR 20100028166A KR 101145124 B1 KR101145124 B1 KR 101145124B1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C23/00—Alloys based on magnesium
Abstract
Description
The present invention relates to a method for dissolving magnesium or magnesium metal.
Magnesium alloy solution melted at high temperature, that is, molten metal is easily ignited. Solvent (Flux) or a protective gas is used as a method of preventing the ignition of such magnesium alloy molten metal.
Solvent prevents ignition during operation by blocking reaction between molten metal and oxygen. The composition of the solvent is a mixture of MgCl 2 , KCl and other metal chlorides and in some cases contains small amounts of CaF 2 and MgO. Further, the protective gas is, by minimizing the exposure area by the molten metal or the like and densification characteristics of oxide film changes in the molten metal surface and serves to protect the molten metal, with a protective gas species is SO 2, CO 2, an inert gas, SF 6, HFC- 134a, Novec ™ 612, mixed gas thereof, and the like.
However, the use of such a solvent not only causes the loss of a part of the melt due to the reaction between the molten magnesium and the solvent, but also causes the reaction product to flow in the casting process, thereby degrading the mechanical and corrosion resistance of the final product.
In addition, the protective gas for suppressing the ignition of the magnesium alloy molten metal is mostly harmful to the human body, and not only corrode iron equipment, but also classified as a greenhouse gas, its use is strictly limited. For example, the SF6 gas has a global warming effect of 23,900 times that of CO 2 gas, and thus, many studies have been under way to prevent the use of SF6 gas in developed countries and replace the gas.
The present invention is to secure an eco-friendly melting technology to achieve the flame retardancy of the magnesium alloy and to suppress the use of a protective gas.
SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned conventional problems, and to provide a magnesium alloy and a method of manufacturing the same, which reduces or does not use a protective gas. That is, it is to increase the oxidation and ignition resistance of the molten magnesium.
Another object of the present invention is to prevent the contamination of the melt generated by the use of the protective gas. The present invention provides a magnesium alloy for improving the cleanliness of the molten metal in the melting furnace, during the transfer of the molten metal or during the pouring of the molten metal, and a method of manufacturing the same.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the particular embodiments that are described. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, There will be.
The method for dissolving the magnesium metal of the present invention for achieving the above object is an alkali metal oxide, an alkali metal compound, an alkaline earth metal oxide, an alkaline earth metal compound or a mixture thereof on a solid magnesium metal before being heated for melting. Covering at least one of the materials; And covering the material and dissolving it by applying heat to the magnesium-based metal.
In the dissolving step, further comprising the step of further supplying the alkali metal oxide, alkali metal compound, alkaline earth metal oxide, alkaline earth metal compound or a mixture thereof to the surface.
A method for dissolving other magnesium metal according to the present invention for achieving the above object, in a heat transfer or thermal dissolution before the metal applying for dissolution over magnesium metal in solid state SF 6 or a mixture of SF 6 and CO 2 Supplying gas; Dissolving by heating the solid magnesium metal; Covering at least one of an alkali metal oxide, an alkali metal compound, an alkaline earth metal oxide, an alkaline earth metal compound, or a mixture thereof on the molten melt; And stirring the molten metal until it is exhausted by causing a surface reaction with the alkali metal oxide, the alkali metal compound, the alkaline earth metal oxide, the alkaline earth metal compound or a mixture thereof and the mixture covered on the molten metal. .
Specifically, the input amount of the alkali metal oxide, alkali metal compound, alkaline earth metal oxide, alkaline earth metal compound or a mixture thereof is characterized in that up to 30wt% of the total molten metal.
The alkali metal oxide, an alkali metal compound, an alkaline earth metal oxide, an alkaline earth metal compound or a mixture thereof is characterized in that they are sequentially covered at a time interval.
Another method of dissolving the magnesium metal of the present invention for achieving the above object, the step of melting by applying heat to the magnesium-based metal; And before the dissolved magnesium-based metal ignites, any one of an alkali metal oxide, an alkali metal compound, an alkaline earth metal oxide, an alkaline earth metal compound, or a mixture thereof is applied to the surface of the molten metal to cause a surface reaction with the molten metal. It characterized in that it comprises a step.
The alkali metal oxide, alkali metal compound, alkaline earth metal oxide, alkaline earth metal compound or a mixture thereof is characterized in that the calcium compound.
The alkali metal oxide, alkali metal compound, alkaline earth metal oxide, alkaline earth metal compound or a mixture thereof is characterized in that the powder.
Another method of dissolving the magnesium metal of the present invention for achieving the above object comprises the steps of supplying a ignition inhibiting gas on the solid magnesium-based metal before applying heat for melting; Dissolving by heating the solid magnesium metal; Covering at least one of the alkali metal oxide, the alkali metal compound, the alkaline earth metal oxide, the alkaline earth metal compound, or a mixture thereof on the dissolved melt; And stirring the molten metal until the material covered on the molten metal is exhausted by causing a surface reaction with the molten metal.
Another method of dissolving the magnesium metal of the present invention for achieving the above object, the step of supplying a protective gas on the magnesium-based metal at 300 ℃ or more after applying heat; Dissolving by adding sufficient heat to dissolve the solid magnesium-based metal further; Covering at least one of an alkali metal oxide, an alkali metal compound, an alkaline earth metal oxide, an alkaline earth metal compound, or a mixture thereof on the molten melt; And stirring the molten metal until the material covered on the molten metal is exhausted by causing a surface reaction with the molten metal.
As described above, the present invention can suppress the ignition by increasing the ignition temperature during melting for the manufacture of magnesium alloy, and reduce or eliminate the amount of the protective gas classified as a greenhouse gas by adding an additive that inhibits oxidation. Can be.
In addition, since the present invention essentially removes impurities generated by ignition during the manufacturing process of magnesium alloy, the cleanliness of the molten metal may be improved when the molten metal is transported or the molten metal is injected.
In addition, the present invention can be purchased at low cost by using an additive (at least one selected from alkali metal oxide, alkali metal compound, alkaline earth metal compound) added during the dissolution process of magnesium alloy, thereby reducing the use and removal of the protective gas In addition to the cost savings, additive costs are also reduced.
1 is an embodiment for dissolving a magnesium-based alloy according to the present invention.
Figure 2 is another embodiment for dissolving the magnesium-based alloy according to the present invention.
FIG. 3 is an exemplary view illustrating a reaction sequence generated when alkaline earth metal oxide (CaO), which is one of the additives in the present invention, is used as in the case of FIG.
4 is an exemplary diagram in which alkaline earth metal oxide (CaO), which is one of the additives in the present invention, is dissociated through stirring of a molten magnesium upper layer.
5 and 6 are graphs showing the results of the protective gas reduction experiment of the magnesium alloy prepared by the method for producing a magnesium-based alloy according to the present invention.
Figure 7 is a graph showing the TGA test results of the magnesium alloy prepared by the method for producing a magnesium-based alloy according to the present invention.
8 and 9 are graphs showing the results of the AES experiment of the magnesium alloy prepared by the method for producing a magnesium-based alloy according to the present invention.
10 is a graph showing the ignition temperature in the atmosphere and nitrogen atmosphere of the magnesium alloy prepared by the method for producing a magnesium-based alloy according to the present invention.
11 is a graph showing the ignition temperature in the atmosphere and nitrogen atmosphere of the magnesium alloy prepared by the method for producing a magnesium-based alloy according to the present invention.
12 is a photograph of the billet surface of the magnesium alloy prepared by the method for producing a magnesium-based alloy according to the present invention.
13 is a graph showing the ignition temperature of the magnesium alloy prepared by the method for producing a magnesium-based alloy according to the present invention.
14 is a graph of the ignition temperature of the magnesium alloy prepared by the method for producing a magnesium-based alloy according to the present invention.
15 is a graph of the ignition temperature of the magnesium alloy prepared by the method for producing a magnesium-based alloy according to the present invention.
16 is a graph of the ignition temperature of the magnesium alloy prepared by the method for producing a magnesium-based alloy according to the present invention.
17 and 18 are graphs showing the results of ignition experiments of the magnesium alloy prepared by the method for producing a magnesium-based alloy according to the present invention.
19 and 20 are graphs showing the results of the protective gas reduction experiment of the magnesium alloy prepared by the method for producing a magnesium-based alloy according to the present invention.
21 and 22 are graphs showing the results of the ignition experiment of the magnesium alloy prepared by the method for producing a magnesium-based alloy according to the present invention.
23 to 25 are photographs showing the surface of the magnesium alloy prepared in the absence of the protective gas, the protective gas and according to the method of the present invention.
FIG. 26 shows the results of a DTA test in a dry air atmosphere to determine the effect of CaO addition on the ignition characteristics of the AZ91D magnesium alloy.
FIG. 27 shows the results of a DTA test in a dry air atmosphere to determine the effect of SrO addition on the ignition characteristics of the AZ31 magnesium alloy.
28 is a result of measuring the time until the fire by heating using a torch under the same conditions in order to compare the fire property of the CaO-added magnesium alloy with conventional commercial high temperature magnesium alloy.
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.
In the present invention, an additive is added for the purpose of suppressing or delaying ignition when dissolving the magnesium metal. The dosing can be applied onto the solid magnesium metal before it is heated for dissolution. Alternatively, the coating may be applied during dissolution by applying heat or after the heat is completely applied to form a liquid and before ignition. In this case, when the magnesium metal is liquefied, ignition occurs suddenly, so that the ignition suppression gas may be previously put on the solid metal. After applying insufficient heat to dissolve, the protective gas may be supplied onto the magnesium-based metal at 300 ° C. or higher, and then additives may be supplied after dissolving by adding additional heat to the metal.
Materials used as additives in the present invention may be alkali metal oxides, alkali metal compounds, alkaline earth metal oxides, alkaline earth metal compounds and their equivalents, and mixtures thereof. In particular, calcium-based compounds such as calcium oxide (eg CaO) or calcium compounds (eg Ca (OH) 2) are effective.
Conventional ignition suppression gas (melt protection gas) serves to protect the molten metal by minimizing the exposed molten metal surface due to densification of oxide film on the surface of the molten metal and changes in properties. Examples of the protective gas include SO 2 , CO 2 , inert gas, SF 6 , HFC-134a, Novec TM 612 and mixed gas thereof. Mainly, a mixed gas of SF 6 or SF 6 and CO 2 gas is used.
The present invention can be applied in the step of preparing a magnesium alloy by dissolving a magnesium-based metal or magnesium (hereinafter referred to as 'magnesium metal' in the description and claims).
One example of dissolving a magnesium metal in the present invention is the step of adding a protective gas as shown in Figure 1 (S1), forming a magnesium molten metal (S2), and adding an additive to the molten metal (S3) And stirring the molten metal and the additive (S4). Another method of dissolving magnesium metal in connection with the present invention includes applying an additive (S11), forming a molten magnesium (S12), and stirring as shown in FIG.
The magnesium molten metal forming step (S1 or S11) is put into the crucible to provide a temperature of 400 to 800 ℃ in a protective gas atmosphere. In the present invention, the temperature for dissolving the magnesium or magnesium alloy means the temperature at which the pure magnesium metal melts and the temperature at which the magnesium alloy melts. Depending on the type of alloy, the melting temperature may be different. Apart from the timing of the addition of additives, the magnesium and the magnesium alloy are preferably completely dissolved in order for the additive and the molten metal to sufficiently react. In other words, as can be seen in Figure 2, the additive may be added before the temperature on the solid magnesium-based metal or at a temperature that the temperature is not high enough to melt the metal. Alternatively, the ignition inhibiting gas may be used in the state of delaying or suppressing the initial ignition.
The present invention can be used to dissolve any magnesium alloy commonly used in the industry. 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, Mg-Al, Mg-Al-Re, Mg-Al-Sn, Mg-Zn-Sn, Mg-Si, Mg-Zn-Y and their equivalents may be any one selected from, but the magnesium alloy is not limited to the present invention.
The additive used in the step S3 or S11 is added to the magnesium molten metal in powder form. Here, the additive is preferably in a powder state to promote the reaction with the magnesium alloy. Preferably, the addition of a powdered state is desirable in order to increase the reaction surface area for an efficient reaction.
Here, the additive used in the additive addition step may be an alkali metal oxide, an alkali metal compound, an alkaline earth metal oxide, an alkaline earth metal compound and equivalents thereof, and a mixture thereof.
The alkali metal oxide may be at least one selected from sodium oxide, potassium oxide, and equivalents thereof. The alkaline earth metal oxide may be at least one selected from beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, and equivalents thereof. The alkaline earth metal compound may be at least one selected from calcium carbide (CaC 2), calcium cyanamide (CaCN 2), calcium carbonate (CaCO 3), calcium sulfate hemihydrate (CaSO 4), and equivalents thereof.
In particular, calcium-based compounds such as CaO or Ca (OH) 2 are effective. However, the additive is not limited to this kind. In other words, the additive may react with the molten metal so as to increase the ignition temperature of the magnesium alloy, reduce the oxidizing power, and reduce the required amount of the protective gas.
As an additive, 0.0001 to 30 wt% may be added to the molten metal. When the additive is less than 0.0001 wt%, the effect by the additive (increasing ignition temperature, decreasing oxidizing power, and decreasing protective gas) is small. In addition, when the additive exceeds 30wt%, the original magnesium or magnesium alloy does not appear. In the present invention, it was confirmed that the additive is differentiated from the fire property of the general magnesium alloy even if only a small amount (0.0001wt% or more).
In addition, the additive used in the additive addition step may have a size of 0.1 ~ 500㎛. If the size of the additive is too fine, less than 0.1㎛, it is difficult to be scattered by the sublimated magnesium or hot air to enter the furnace. Then, they coagulate with each other and become agglomerated without easily mixing with the molten metal in the liquid phase. . In addition, when the size of the additive exceeds 500㎛, it is not preferable in view of increasing the surface area as mentioned when the additive is too thick. The particle size of the ideal powder is preferably 500 탆 or less. More preferably not more than 200 mu m.
In the stirring step (S3), the magnesium molten metal is stirred for 1 second to 60 minutes per 0.1 wt% of the additive.
If the stirring time is less than 1 second / 0.1 wt%, the additives are not sufficiently mixed in the molten magnesium, and if the stirring time exceeds 60 minutes / 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 molten metal and the amount of additives added.
The addition of the additive powder may be carried out by a method of adding a necessary amount at a time, but in terms of promoting the reaction and lowering the possibility of agglomeration of the powder, it is also preferable to add the powder sequentially by dividing it again or appropriately with a time difference after the first feeding.
Stirring Method and Conditions
It is important to cover the additive added in the present invention on the molten metal. Therefore, it is important to induce reaction with the molten metal. Stirring is preferred for efficient reaction of the melt with the additives. Of course, a small amount of additives may not be stirred. The main method of stirring is artificially stirring (mechanical stirring) the molten metal from the outside. In the case of mechanical stirring, the additive powder to be added may be appropriately stirred so as not to agglomerate. The ultimate goal of stirring is to properly induce the reaction of the molten metal with the incoming powder.
The time for stirring may vary depending on the temperature of the molten metal and the state of the injected powder (preheated state, etc.). Preferably, stirring is performed until no powder is visible on the surface of the molten metal. The reason is indirectly determined that the powder has a specific gravity lower than that of the molten metal, so that it flows on the molten metal in a steady state, and the reaction is sufficient when the powder is not visible on the molten metal. Sufficient reaction herein means a state in which the additive is exhausted by substantially reacting with the molten metal. As the molten metal reacts with the additive, the molten metal of the magnesium metal rapidly reduces the tendency of ignition even without using a gas for suppressing ignition or other known ignition methods. In the case where the additive is added before the magnesium metal is dissolved, the solid may be dissolved by heating after the addition, followed by stirring.
Stirring Time
In the timing of stirring, it is effective to stir after the molten metal is formed by applying heat to the magnesium metal. In addition, after the powder receives heat from the molten metal to reach a predetermined temperature or more, the reaction may be accelerated by starting stirring. Stirring is continued until no additive powder is detected on the surface of the melt. Agitation is complete after the additive has been exhausted by the reaction.
Surface reaction
When the additive is added to the molten metal, it is suspended on the surface of the molten metal without sinking into the molten metal due to the specific gravity difference.
In the present invention, it is important to create a reaction environment so that the oxide reacts on the surface of the molten metal rather than reacting in the molten metal. To do this, it is important not to forcibly add additives suspended on the surface of the melt into the melt. It is important to simply spread the additive spread on the surface to spread evenly over the surface of the exposed 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 (upper surface) was more responsive to the atmosphere and to the exposed powder. One of the additives had better effect in contact with the atmosphere. The results were not good under vacuum or atmospheric gas. For sufficient reaction, it is necessary to stir the upper layer to induce the surface reaction.
It is preferable that the agitation is performed at the upper layer portion of the depth of the molten metal from the surface of the molten metal to about 20% of the entire depth of the molten metal. At a depth of 20% or more, it is difficult to cause the surface reaction suggested by the present invention as a preferable example. 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 melt by actually inducing the floating additive to be located in the 10% upper layer to the depth of the melt.
Through the reaction of the melt with the additive, the additive is exhausted so as not to remain at least partially or substantially in the magnesium alloy.
As an example, exhausting the alkaline earth metal oxide, which is one of the additives, removes the oxygen component from the alkaline earth metal oxide. The oxygen component may be removed in the form of oxygen (O 2 ) gas, or may be removed in the form of dross or sludge through association with magnesium or its alloying elements in the molten metal. Then, the oxygen component is substantially removed over the surface of the molten metal through agitation of the molten upper layer. 3 is a case where the protective gas is first applied to the surface of the molten metal in the present invention, and then the metal is dissolved. After dissolution, an illustration of the dissociation of the alkaline earth metal oxide, which is one of the additives, by stirring the upper layer of the molten magnesium.
The alkali metal or alkaline earth metal produced as a result of the exhaustion (dissociation) of the additives is reacted so as not to remain at least partially or substantially in the magnesium alloy. Here, the alkaline earth metal produced as a result of dissociation is compounded with at least one of magnesium, aluminum in the magnesium alloy, and other alloy elements (components) in the molten metal so as not to remain substantially. Herein, the compound refers to an intermetallic compound formed by combining a metal and a metal. In Figure 3, the additive exhaustion step (S43 + S5) and the compound formation step (S6) is described by dividing into steps to aid in understanding the reaction that occurs at the same time.
Here is the formula of pure magnesium and alloy magnesium dissociated and reacted with calcium oxide (one of the additives).
In the case of pure magnesium molten metal, the magnesium component in the molten metal reacts with alkaline earth metal to form a magnesium (alkaline metal) compound. For example, when the alkaline earth metal oxide is CaO, Mg 2 Ca is formed. Oxygen, which forms CaO, becomes O 2 and is discharged out of the molten metal or combined with Mg to form MgO and discharged in the form of dross (see
Pure Mg + CaO -> Mg (Matrix) + Mg 2 Ca
... [O 2 occurrence + MgO dross occurrence]
In the case of magnesium alloy molten metal, the magnesium component in the molten metal reacts with alkaline earth metal to form a magnesium (alkaline earth metal) compound or an aluminum (alkaline earth metal) compound. Also, magnesium and aluminum together with magnesium form compounds with alkaline earth metals. For example, when the alkaline earth metal oxide is CaO, Mg 2 Ca, Al 2 Ca, or (Mg, Al, other alloying elements) 2 Ca is formed. Oxygen, which is composed of CaO, becomes O 2 and is discharged out of the molten metal as in the case of pure magnesium, or it is combined with Mg to be MgO and discharged in the form of dross (see Scheme 2 below).
Here, Ca provided in the additive showed a tendency to compound with other components than Mg in the alloy.
Scheme 2
Mg Alloy + CaO-> Mg Alloy (Matrix) +
(Mg 2 Ca + Al 2 Ca + (Mg, Al, other alloying elements) 2 Ca}
... [O 2 occurrence + MgO dross occurrence]
As described above, when the magnesium-based metal is manufactured using the present invention, the magnesium alloy may be more economically prepared as compared with the conventional method for producing magnesium alloy. Thus, when dissolving a magnesium alloy in accordance with the present invention, the ignition temperature (° C) is 500 to 1500 ° C, and the ignition resistance characteristic is improved. In addition, as will be described below, the present invention significantly reduces the amount of protective gas used.
5 and 6 are graphs showing the results of the protective gas reduction experiment of the magnesium alloy prepared by the method for producing a magnesium alloy according to the present invention.
The results of FIG. 5 are obtained by experimenting at a die casting working melt temperature of 680 ° C., and the results of FIG. 8 are obtained by experimenting at 720 ° C. (overheated state).
In addition, in FIG. 5 and FIG. 6, "sealed" means a state in which outside air is not introduced, and "unsealed" means a state in which outside air is introduced.
First, as shown in FIG. 5, in an unsealed atmosphere at 680 ° C., 1,000 ppm SF6 gas is contained in AZ91D, AZ91D-0.04wt% CaO, and AZ91D-0.13wt% CaO to suppress ignition. Needed. However, in the absence of air (sealed), about 500 ppm of SF6 gas was required for AZ91D and AZ91D-0.04 wt%, and 300 ppm of SF6 gas was required for AZ91D-0.13 wt% CaO. Therefore, it can be seen that in a condition where air is not introduced at a normal die casting operation temperature, as the amount of the additive is added, the required amount of the protective gas for suppressing ignition decreases.
Next, as shown in Figure 6, in the air inflow (unsealed) in an atmosphere of 720 ℃ (3,200ppm, 2,000ppm in AZ91D, AZ91D-0.04wt% CaO, AZ91D-0.13wt% CaO, respectively, to suppress ignition) 1,000 ppm of SF6 gas was required. However, in the absence of air (sealed), approximately 500 ppm SF6 gas was required for AZ91D and AZ91D-0.04 wt% CaO, and 300 ppm SF6 gas was required for AZ91D-0.13 wt% CaO to suppress ignition. Therefore, it can be seen that the amount of additives required for the protection gas for reducing the ignition decreases as the amount of the additive is increased in the condition that the air is not introduced even at the overheating temperature.
7 is a graph showing the results of the TGA (Thermogravimetry Analyzer) experiment of the magnesium alloy prepared by the method for producing a magnesium alloy according to the present invention.
In FIG. 7, the X axis represents time, and the Y axis represents weight increase (%). In the case of the AZ91D, the weight may increase rapidly over time. That is, the oxidation phenomenon progressed rapidly. In the case of AZ91D-0.14wt% CaO, the weight may gradually increase over time. That is, the oxidation phenomenon proceeded slowly. For example, after 400 minutes AZ91D increased to 113 and AZ91D-0.14wt% CaO to 101.
Therefore, it can be seen from the experimental results that the oxidation phenomenon of the magnesium alloy to which the additive is added is suppressed.
8 and 9 are graphs showing the results of the AES (Atomic Emission Spectrometer) experiment of the magnesium alloy prepared by the method for producing a magnesium alloy according to the present invention.
In Fig. 8, the X axis is the sputtering time and the Y axis is the detection amount. In the case of the AZ91D, about 40 minutes of oxygen is detected until the sputtering time of about 9 minutes, and since that time, oxygen detection decreases. That is, in the case of AZ91D, it means that the oxide film is formed relatively thick.
On the other hand, in the case of AZ91D-0.7wt% CaO, as shown in FIG. 9, about 26 minutes of oxygen is detected up to about 1 minute for the sputtering time, and oxygen detection decreases thereafter. That is, in the case of AZ91D-0.7wt% CaO, it means that the oxide film is formed relatively thin.
Therefore, it can be seen from the experimental results that the oxidation phenomenon of the magnesium alloy to which the additive is added is suppressed.
10 is a graph showing the ignition temperature of the magnesium alloy produced by the method for producing a magnesium alloy according to the present invention.
As shown in Figure 10 it can be seen that the ignition temperature of the magnesium alloy according to the addition amount of calcium oxide increases with the addition amount of the calcium oxide increases. That is, the ignition temperature of the AZ91D magnesium alloy in the atmospheric atmosphere is about 490 ° C, and the ignition temperature in the nitrogen atmosphere is about 510 ° C, whereas the ignition temperature of the magnesium alloy to which calcium oxide is added is about 100 ° C or more depending on the amount added. It can be seen that the ignition temperature has increased.
(Example 1)
11 is a graph showing the ignition temperature in the atmosphere and nitrogen atmosphere of the magnesium alloy prepared by the method for producing a magnesium alloy according to the present invention.
As shown in FIG. 11, the AZ91D magnesium alloy to which strontium oxide was not added has a ignition temperature of approximately 490 ° C. in an atmospheric atmosphere and approximately 510 ° C. in a nitrogen atmosphere. However, the ignition temperature of AZ91D magnesium to which strontium oxide was added increased approximately 100 ° C. or more depending on the amount added.
(Example 2)
12 is a photograph of the billet surface of the magnesium alloy prepared by the method for producing a magnesium alloy according to the present invention.
As shown in FIG. 12, the beryllium oxide, which is the alkaline earth metal oxide, and the billet photograph of the AZ91D magnesium alloy for die casting, in which 0.0001 wt% and 0.5 wt% magnesium oxide were added, respectively, showed a billet even when a small amount of 0.0001 wt% beryllium oxide was added. It can be seen that this shows a clean surface without oxidation or ignition. In addition, a clean billet which was not oxidized or ignited was obtained even by adding 0.5 wt% of magnesium oxide.
13 is a graph showing the ignition temperature of the magnesium alloy prepared by the method for producing a magnesium alloy according to the present invention.
As shown in FIG. 13, the ignition temperature of the AZ91D magnesium alloy for die casting in which beryllium oxide and magnesium oxide were added 0.0001 wt% and 0.5 wt%, respectively, was clearly confirmed. It can be seen that the ignition temperature is improved according to the addition amount, thereby improving mechanical properties and oxidation characteristics.
(Example 3)
14 is a graph of the ignition temperature of the magnesium alloy prepared by the method for producing a magnesium alloy according to the present invention.
As shown in FIG. 14, the AZ91D magnesium alloy to which the calcium-based compound calcium cyanamide was added has a ignition temperature of approximately 540 ° C. in the air. That is, since the ignition temperature of the AZ91D magnesium alloy to which the additive was not added was approximately 510 ° C in the air, the ignition temperature of approximately 30 ° C was increased by the addition of the additive.
(Example 4)
15 is a graph of the ignition temperature of the magnesium alloy prepared by the method for producing a magnesium alloy according to the present invention.
As shown in FIG. 15, the AZ91D magnesium alloy to which the calcium-based compound calcium carbide is added has a ignition temperature of approximately 540 ° C. in nitrogen. That is, since the ignition temperature of the AZ91D magnesium alloy to which the additive was not added was approximately 510 ° C in nitrogen, the ignition temperature of approximately 30 ° C increased by the addition of the additive.
16 is the ignition temperature data of the magnesium alloy prepared by the method for producing a magnesium alloy according to the present invention.
As shown in FIG. 16, the ignition temperature in the air atmosphere is a magnesium alloy (AZ91D-0.007 wt% CaCN 2 /0.03 wt%) to which calcium cyanide (CaCN 2) or calcium carbide (CaC 2 ), which is a calcium compound, is added, respectively. CaC 2 ) all showed a significantly improved ignition temperature of the heat-resistant alloy compared to the pure magnesium alloy (AZ91D), which can be seen that the ignition temperature is greatly improved according to the addition amount of the calcium-based compound.
(Example 5)
17 and 18 are graphs showing the results of ignition experiments of magnesium alloys produced by the method for producing magnesium alloys according to the present invention.
As shown in FIG. 18, when calcium oxide was not added to the AM50 magnesium alloy, the ignition temperature was about 570 ° C. in an air atmosphere, but when about 0.05 wt% of calcium oxide was added, the ignition temperature increased to about 590 ° C. FIG. Moreover, when about 0.15 wt% of calcium oxide was added, the ignition temperature increased to about 610 ° C.
As shown in FIG. 18, when calcium oxide was not added to the AM50 magnesium alloy, the ignition temperature was about 550 ° C. in a nitrogen atmosphere, but when about 0.05 wt% of calcium oxide was added, the ignition temperature increased to about 570 ° C. FIG. Moreover, when about 0.15 wt% of calcium oxide was added, the ignition temperature increased to about 640 ° C.
(Example 6)
19 and 20 are graphs showing the results of the protective gas reduction experiment of the magnesium alloy prepared by the method for producing a magnesium alloy according to the present invention.
The results of FIG. 19 were obtained by experimenting at a die casting working melt temperature of 680 ° C., and the results of FIG. 30 were obtained by experimenting at 720 ° C. (overheated state).
As shown in FIG. 19, 500 ppm of SF6 gas was required at AZ31, AZ31-0.05wt% CaO, and AZ31-0.32wt% CaO in order to suppress ignition in the air (unsealed) state at 680 ° C. . However, in the absence of air (sealed), about 100 ppm of SF6 gas was required for AZ31 and AZ31-0.05 wt% CaO, and 40 ppm of SF6 gas was required for AZ31-0.32 wt% CaO. Therefore, it can be seen that in a condition where air is not introduced at a normal die casting working temperature, as the amount of the additive is added, the required amount of the protective gas for suppressing ignition decreases.
Next, as shown in FIG. 20, in an unsealed state in which air is introduced at 720 ° C., 1,000 ppm SF6 gas is contained in AZ31, AZ31-0.05 wt% CaO, and AZ31-0.32 wt% CaO to suppress ignition. Needed. However, in the absence of air (sealed), about 200 ppm of SF6 gas was required for AZ31, and about 100 ppm of SF6 gas was required for AZ31-0.05 wt% CaO, and AZ31-0.32 wt% CaO to suppress ignition. In the case of 40 ppm SF6 gas was required. Therefore, it can be seen that the amount of additives required for the protection gas for reducing the ignition decreases as the amount of the additive is increased in the condition that the air is not introduced even at the overheating temperature.
21 and 22 are graphs showing the results of ignition experiments of the magnesium alloy prepared by the method for producing a magnesium alloy according to the present invention.
As shown in FIG. 21, when calcium oxide was not added to the AZ31 magnesium alloy, the ignition temperature was about 570 ° C. in an air atmosphere, but when about 0.3 wt% of calcium oxide was added, the ignition temperature increased to about 610 ° C. FIG.
As shown in FIG. 22, when calcium oxide was not added to the AZ31 magnesium alloy, the ignition temperature was about 640 ° C. in a nitrogen atmosphere, but when about 0.3 wt% of calcium oxide was added, the ignition temperature increased to about 690 ° C. FIG.
23 to 25 are photographs showing the surface of the thin cast product of magnesium alloy prepared in the absence of the protective gas, in the presence of the protective gas and according to the method of the present invention.
As shown in FIG. 23, when the magnesium alloy is manufactured without the protective gas, the surface is blackened.
In addition, as shown in FIG. 24, even when a magnesium alloy is manufactured by spraying a protective gas, it can be seen that a crack phenomenon occurs due to the mixing of oxides.
However, when using the invention of the present invention, as shown in Figure 25, when the magnesium alloy is prepared by adding calcium oxide, it can be seen that no ignition phenomenon or crack phenomenon is found.
Figure 26 shows the results of the DTA test in a dry air atmosphere to determine the effect of CaO addition on the ignition characteristics of the AZ91D magnesium alloy. As can be seen in the experimental results of FIG. 36, it can be seen that the ignition temperature increases as the CaO content increases. When the amount of calcium oxide added is 15.7 wt%, it shows a high ignition temperature of about 1300 ° C, and it can be seen that the ignition temperature converges to some extent in the subsequent CaO addition.
Figure 27 shows the results of the DTA test in a dry air atmosphere to determine the effect of SrO addition amount on the ignition characteristics of the AZ31 magnesium alloy. As can be seen from the experimental results of FIG. 37, it can be seen that the ignition temperature increases as the content of strontium oxide increases. When 15.9 wt% of strontium oxide is added to the molten metal of magnesium-based metal, the ignition temperature is increased to 1400 ° C. After that, the ignition temperature is maintained to some extent until the addition of 25.8 wt% SrO.
FIG. 28 is a result of measuring the time to ignition by heating using a torch under the same conditions in order to compare the ignition characteristics of the magnesium alloy added with CaO additives with conventional commercial high temperature magnesium alloys. As shown in the photograph, it can be seen that the magnesium alloy added with CaO is not fired for the longest time compared to other commercial magnesium alloys, and thus, the fire is suppressed. Among the alloys used in the experiment, Mg-3Al-1.13CaO alloy prepared by adding 1.13wt% of CaO showed the highest ignition resistance. In this case, fire occurred only after 200 seconds. In addition, when CaO is added to 1 wt% or more in all the alloys, regardless of the Al content, all alloys can be seen that the fire property is superior to the existing high-temperature magnesium alloy (AS21, AE44, MRI153, MRI230 in FIG. 38). In FIG. 38, Mg-3Al-1.13CaO alloy refers to an alloy prepared by the invention described above by adding 1.13wt% of CaO as an additive to a molten magnesium alloy of Mg-3Al. (The same applies to Mg-6Al-1CaO and Mg-9Al-1.02CaO.)
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 (13)
Covering at least one of an alkali metal oxide, an alkali metal compound, an alkaline earth metal oxide, an alkaline earth metal compound, or a mixture thereof on a solid magnesium-based metal before applying heat for melting; And
Covering the material and dissolving it by applying heat to a magnesium-based metal;
Dissolving method of magnesium-based metal comprising a.
In the dissolving step, further comprising the step of further supplying the alkali metal oxide, alkali metal compound, alkaline earth metal oxide, alkaline earth metal compound or a mixture thereof to the surface.
Supplying a mixed gas of SF 6 or SF 6 and CO 2 to the solid magnesium-based metal at a temperature before applying heat for melting or before melting of the metal;
Dissolving by heating the solid magnesium metal;
Covering at least one of an alkali metal oxide, an alkali metal compound, an alkaline earth metal oxide, an alkaline earth metal compound, or a mixture thereof on the molten melt; And
Stirring the molten metal until it is exhausted by causing a surface reaction with the alkali metal oxide, an alkali metal compound, an alkaline earth metal oxide, an alkaline earth metal compound or a mixture thereof and the molten metal covered on the molten metal;
Dissolving method of magnesium-based metal comprising a.
The alkali metal oxide, alkali metal compound, alkaline earth metal oxide, alkaline earth metal compound or a mixture of these mixtures of magnesium metal, characterized in that up to 30wt% of the total molten metal.
Method for dissolving the magnesium-based metal, characterized in that the alkali metal oxide, alkali metal compound, alkaline earth metal oxide, alkaline earth metal compound or a mixture thereof are sequentially covered at a time interval to be supplied to the molten metal.
Dissolving by heating the magnesium metal; And
Applying a substance of any one of an alkali metal oxide, an alkali metal compound, an alkaline earth metal oxide, an alkaline earth metal compound, or a mixture thereof to the surface of the molten metal to cause a surface reaction with the molten magnesium-based metal before firing;
Dissolving method of magnesium-based metal comprising a.
The alkali metal oxide, alkali metal compound, alkaline earth metal oxide, alkaline earth metal compound or a mixture thereof is a magnesium-based metal dissolution method, characterized in that the calcium compound.
The method may further include stirring the molten metal until the dissolved magnesium-based metal is ignited until the alkali metal oxide, the alkali metal compound, the alkaline earth metal oxide, the alkaline earth metal compound or a mixture thereof is exhausted by the reaction. Method of dissolving magnesium metal.
The alkali metal oxide, alkali metal compound, alkaline earth metal oxide, alkaline earth metal compound or a mixture thereof is a method of dissolving a magnesium-based metal, characterized in that the powder.
Dissolution method of the magnesium-based metal, characterized in that the particle size of the powder is 0.1 to 200㎛.
Supplying a ignition inhibiting gas onto the solid magnesium metal before applying heat for melting;
Dissolving by heating the solid magnesium metal;
Covering at least one of the alkali metal oxide, the alkali metal compound, the alkaline earth metal oxide, the alkaline earth metal compound, or a mixture thereof on the dissolved melt; And
Stirring the molten metal until the material covered on the molten metal has exhausted by causing a surface reaction with the molten metal;
Dissolving method of magnesium-based metal comprising a.
The stirring is a method of dissolving the magnesium-based metal, characterized in that the upper part stirring to induce a surface reaction.
Supplying a protective gas on the magnesium-based metal at 300 ° C. or more after applying heat for melting;
Dissolving by heating the solid magnesium metal;
Covering at least one of an alkali metal oxide, an alkali metal compound, an alkaline earth metal oxide, an alkaline earth metal compound, or a mixture thereof on the molten melt; And
Stirring the melt until the material covered on the melt is exhausted by reaction with the melt;
Dissolving method of magnesium-based metal comprising a.
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| KR20100028166A KR101145124B1 (en) | 2010-03-29 | 2010-03-29 | Melting method for magnesium alloy and manufacturing method thereof |
| PCT/KR2011/001845 WO2011122776A2 (en) | 2010-03-29 | 2011-03-16 | Melting method of magnesium-based metal and magnesium alloy manufactured using the same |
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| KR102462227B1 (en) | 2021-05-04 | 2022-11-03 | 액츠테크놀러지스 주식회사 | Al-Mg-Zr-Si high-strength aluminum alloy for 3D printing and its manufacturing method |
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| CN105400972B (en) * | 2015-11-30 | 2017-07-11 | 贵州航天风华精密设备有限公司 | A kind of process for smelting magnesium alloy |
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| KR20060094734A (en) * | 2005-02-25 | 2006-08-30 | 한국생산기술연구원 | Cao added magnesium and magnesium alloys and their manufacturing method thereof |
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| US4705561A (en) * | 1986-01-27 | 1987-11-10 | The Dow Chemical Company | Magnesium calcium oxide composite |
| KR100959830B1 (en) * | 2007-12-28 | 2010-05-28 | 한국생산기술연구원 | CaX Chemical Compound Added Magnesium and Magnesium Alloys and their Manufacturing Method Thereof |
| US8506733B2 (en) * | 2008-03-11 | 2013-08-13 | Topy Kogyo Kabusikikaisya | Al2Ca-containing magnesium-based composite material |
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| 한국주조공학회지, 제29권, 제3호(2009.06.) pp.101-112. * |
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| KR102462227B1 (en) | 2021-05-04 | 2022-11-03 | 액츠테크놀러지스 주식회사 | Al-Mg-Zr-Si high-strength aluminum alloy for 3D printing and its manufacturing method |
| WO2022235053A1 (en) | 2021-05-04 | 2022-11-10 | 액츠테크놀러지스 주식회사 | High-strength aluminum alloy for 3d printing, and manufacturing method therefor |
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| KR20110108775A (en) | 2011-10-06 |
| WO2011122776A2 (en) | 2011-10-06 |
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