JPS6220846A - Manufacture of foamed metal - Google Patents

Abstract

PURPOSE:To manufacture a foamed Al having cell structure of bubble homogeneous in shape by melting Al or an alloy thereof, agitating the above with the addition of specific amounts of Ca to increase viscosity, further agitating with the addition of specific amounts of TiH2 and foaming the above in a hermetically sealed state. CONSTITUTION:Ca, as a thickener, is added by 0.2-8wt% to molten Al 2 held in a mold 1 heated by a heater 4 and the mixture is agitated by an agitator 3 to undergo regulation of Al viscosity, which is then agitated with the addition of 1-3% powdered TiH2 as a foaming agent so as to be foamed. In this way, internal gas pressure P2 is increased and overcomes the sum P1 of atmospheric pressure and viscous resistance of Al and therefore the numerous bubbles in Al 2 are expanded. Subsequently, the mold 1 is closed with a preheated cover 9 and, while releasing air in an internal space 8 from an outlet hole, the formed Al 20 is expanded and allowed to fill the mold 1 so as to close the outlet hole 10. In this way, with maintaining the pressure P2 of the bubbles in the foamed Al 20, the cell structure homogeneous in size and shape can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing a foamed metal in which a large number of closed cells constituting the foamed metal have uniform sizes and do not cause internal shrinkage.

(Prior art) As a means of obtaining a metal foam, a foam material is generated by thermal decomposition near the melting point of the metal, and the viscosity of the molten metal is controlled by collecting the generated gas in the melt to form bubbles. A thickening agent is required, and the selection of these materials and methods requires 1.
．． 1, various foams can be obtained. This foamed metal has many closed cells, is lightweight, and has been developed as a new material with many excellent functions such as mechanical and thermal properties. Although much research has been carried out, it has not been put into practical use due to various technical limitations. The reason for this is that when large-scale materials are produced on an industrial scale, the size of the bubbles becomes uneven, and when the metal solidifies, there is a problem that shrinkage occurs inside the material. I needed a problem solved.

(Purpose of the Invention) The present invention was made to solve such conventional problems, and provides a method for industrially manufacturing a foamed metal in which a large number of cells are homogeneous and do not shrink inside. It is intended to encourage

(Structure of the Invention) This defense states that by adding a foaming agent and a thickening agent to molten metal,
! In the method of manufacturing a foamed metal consisting of a large number of closed cells by IT, the entire mold is heated to a temperature higher than the melting point of the foamed metal, and stirring is stopped to start foaming and the cells grow. During the process, the mold is sealed with a release port for air handling, and the foam material decomposes due to heat, resulting in the expansion of a large number of bubbles, which release the air inside the mold to the outside of the mold, and the foamed metal is released into the mold. By filling the entire interior, the discharge port is closed by the molten foamed metal and the mold is sealed, and the internal pressure of the many bubbles increases within the sealed mold, resulting in a balance between the pressures of the bubbles. A uniform cell structure is formed at the bottom, and then heating of the mold is stopped to allow the foamed metal to cool and solidify. In addition, using aluminum or its alloy as the molten metal, calcium as the thickener, and titanium hydride as the foaming material, 0.2 to 8% of the above thickener was added and stirred to adjust the viscosity of the aluminum. , 1 to 3% titanium hydride powder may be added and stirred to foam.

(Example) In FIG. 1, a mold 1 is charged with molten aluminum 2 to which a foaming material has been added, and the molten aluminum 2 is stirred in a stirring basin 3, and a heater 4 is used to heat the mold 1. are arranged around the mold 1. Figure 1 (B)
As shown in Figure 2, the foamed aluminum decomposes, causing the molten aluminum 2 to expand and become foamed aluminum 20, increasing the internal gas pressure (P2), which increases the pressure due to the difference between the atmospheric pressure Pa and the viscous resistance of the molten aluminum. C that overcomes the sum P1 Many bubbles expand, but since one side of the mold 1 is exposed to the atmosphere and a free surface is formed, each bubble expands arbitrarily due to its own gas pressure, resulting in large jagged edges. This results in a collection of bubbles with extremely irregular shapes.

FIG. 2 is a diagram showing the relationship between such gas pressure and the volume of foamed aluminum.

In the figure, the volume Vo of aluminum at time A when the foaming material is added to the aluminum and stirring is started is as follows: While adding the foaming material, the gas pressure PA to the point is almost maintained.
It expands to the volume VQ at point B.

In this case, since there is a difference in the addition time of the foaming material, there is also a difference in the gas ω that has already been generated, and therefore the volume of each bubble becomes uneven. The volume of the foamed aluminum 20 increases with each opening from the volume ■Ω when the addition of the foam material reaches the end point (point B) to the point C when solidification is completed, and expands to VS while increasing the gas pressure. .

If foaming is continued according to the conventional method in the state shown in FIG. 1(B), the formed aluminum foam 20 will solidify fastest on the free surface in contact with the outside air, and this will be destroyed by the gas pressure, resulting in As shown in FIG. 7, two rotators are generated. Furthermore, inside the aluminum foam 20, the size of each bubble 21 is uneven, and large pores 22 are formed near the center where it finally solidifies. aluminum foam 20
When the gas is solidified and cooled to room temperature, the gas inside each bubble is also cooled, and as a result, the pressure decreases from the point Jζ shown in FIG. 2 (1).

FIG. 3 is a diagram showing the relationship between aluminum temperature T, elapsed time $1, and operations at each stage.

In the figure, point a1 is the melting point of aluminum (M, P,
) At a higher temperature Ta, the mixing of the foaming material and the start of stirring, point a2 is the end of stirring, and point a3 is the time when heating of mold 1 is stopped and covered. Foaming is performed while maintaining the humidity at Ta. When the foamed aluminum reaches its melting point at point b t, point cru solidification is completed, and it is taken out from the mold 1 at point d when it reaches room temperature (R, T,).

The basic operation in the method according to this invention is at point a2 in Figure 3, that is, add the foam material and 1! The purpose is to close the mold 1 at the time when i'\ is completed. That is, as shown in FIG. 1(C), a lid 9 preheated to a foaming temperature Ta is attached to the mold 1, and the mold 1 is hermetically sealed with an air outlet 10 formed therein. A plurality of discharge ports 10 may be formed at random positions. The reason why the lid 9 is preheated is because if the temperature of the lid is low, the free expansion surface of the foaming aluminum will be below the melting point of aluminum, and sufficient bubble growth will not occur. Further, the relationship between the size of the mold 1 and the amount of molten aluminum 2 charged into the mold 1 is set so that the final product has a predetermined foaming rate.

When the pressure P2 of the generated gas in the foamed aluminum 2o becomes larger than the air pressure P3 in the internal space 8 of the closed mold 1, the air bubbles in the foamed aluminum 20 expand and the air in the internal space 8 is released 1110. released from. When the foamed aluminum 20 continues to expand () and fills the closed mold 1, the outlet 1 opens as shown in FIG. 1(D).
0 is closed with molten aluminum 20, and the inside of the mold 1 is completely sealed. Then, the bubbles that have not yet sufficiently released the gas in the foam material and become larger form a hill structure with a uniform shape and size that maintains a balance while maintaining the pressure P2. In other words, if the mold 1 is not sealed, the bubbles near the free surface will expand and become larger than the bubbles in other parts, but if the mold 1 is sealed as described above, the bubbles will expand due to the pressure of other bubbles. Expansion is prevented and the bubbles are therefore approximately uniform in size.

In FIG. 4, the foam material is mixed and stirred at point A1, preheated A9 is attached, and the mold 1 is sealed.From point A2, the internal pressure P2 of the bubbles increases, and the foamed aluminum 20 fills the mold 1 at point B. 'C''t, the internal pressure of the bubbles increases to pc while the volume Vρ remains constant, forming a uniform aggregate of bubbles. At this point (corresponding to point a3 in Figure 3), the mold is taken out of the furnace. When cooled to room temperature, a homogeneous foamed aluminum 24 in which each cell 23 has approximately the same size is obtained as shown in Fig. 5.The shape of the mold used in the above method can be modified in various ways. For example, a spherical mold 5 as shown in FIGS. 6(A) and 6(B) may be used.

In the same figure, (Δ) is molten aluminum 2 in the spherical mold.
(B) shows aluminum foam 20
The mold 5 is filled with so that the discharge port 10 is blocked.

In the above example, aluminum was melted at 720° C., and 1.6% by weight of calcium was added thereto and stirred to increase the viscosity. Adjusting the viscosity of aluminum can also be done by air blowing without adding a thickening agent, but this method traps the pyrolysis gases from the foam in the molten metal to provide the viscosity necessary to maintain closed cells. This requires a very long period of stirring. On the other hand, if calcium, which has a strong affinity for oxygen, is added as a thickener and stirred, the viscosity can be increased in an extremely short time. In this case, if the amount of calcium added is less than 0.2% by weight, it will take a long time to stir, resulting in extremely inefficient and wasteful accumulation. Further, if it is 8% by weight or less, the purpose of thickening can be sufficiently achieved.

Further, if the molten metal whose viscosity has been adjusted is maintained at 720° C. and 1.6 weight percent of titanium hydride powder is added as a foaming agent and stirred, a homogeneous foam with a porosity of about 90% can be obtained. In this case, if the addition m of titanium hydride is less than iin%, the generation of bubbles will not be sufficient, and if it exceeds 3%, the generation of bubbles will be excessive, and stirring for a period of time may be required. Otherwise, the film structure may be destroyed or it becomes difficult to obtain a uniform film structure, so the addition ω of titanium hydride is appropriately set to 1 to 3%. In addition, as the foaming material, it is also possible to use synthetic calcium silicate hydrate fine powder or the like instead of titanium hydride.

J3. In the above embodiment, foamed aluminum was explained using calcium as the thickening agent and Mizuki-based titanium as the foaming material, but foaming may be performed using shirasu baluno or other materials.

(Effects of the Invention) As explained above, in this invention, the foamed metal expands and fills the entire inside of the mold, and the molten and filled foamed metal closes the discharge port and seals the mold. , a uniform cell structure is formed by increasing the internal pressure of a large number of bubbles in a closed mold, balancing the pressure of the bubble phase U, and forming cells made of bubbles of uniform size and shape. Foams with a structure can be produced, and production on an industrial scale is also possible.

Therefore, this foam material has high UIA sound absorption properties, and is useful as a new material having high heat insulation effects, mechanical properties, and machinability. Note that the method of the present invention can also be applied to the production of foams of metals other than aluminum.

[Brief explanation of drawings]

Figures 1 (A) to (D>) are explanatory diagrams of the steps of carrying out the present invention, Figure 2 is a pressure-volume diagram of foamed metal according to the conventional method, and Figure 3 is a temperature-hour and operating line diagram of the present invention. 4 is a pressure-volume diagram obtained by the method of this invention, FIG. 5 is a conceptual diagram of foamed metal produced by this invention, and FIG. 6 (A>, (
B) is a schematic explanatory diagram showing one example of an apparatus used for carrying out the present invention, and FIG. 7 is a conceptual diagram of a foamed metal obtained by a conventional method. DESCRIPTION OF SYMBOLS 1... Mold, 2... Molten aluminum, 3... Stirrer, 4... Heater, 9... Lid, 10... Outlet, 20.24... Foamed aluminum, 23... ...Bubbles. Special Accommodation Applicant: Agency of Industrial Science and Technology Director-General Shinko Wire Co., Ltd. Agent
Patent Attorney Etsushi Kotani Patent Attorney
Long 1) Masamukai Patent Attorney Yasuo Itaya Figure 1 Figure 1 (A
> (f3) Fig. 1 Fig. 1 Fig. 2 Fig. 3 Fig. E￥-Kan 111 't='': (Voluntary)
6゜1985 571'2-gll 1, = JS ft Table 13 1985 1Fl Revised Application No. 160804 2, title of invention 7゜Method for manufacturing foam metal 3, amendment 1J-
8゜Relationship with f1 14th edition Applicant name (114) Industry 1 Director Tatsu Todoroki
9゜ (1 idiot) 4. Designated agent address: Aza Nono, Shukumachi, Shimasu City, Saga Prefecture] 807-1 Sub-agent (Designated agent: Agency of Industrial Science and Technology, Kyushu [Sub-agent of the Director of 7 Technical Testing Centers] Address: Osaka 1] Nishiki-cho, Ichinishi-ku] - Item 10 No. 3)) Table of contents of amendment order Voluntary amendment Contents of amendments and full text of specification As attached, Mei IB Book 1, Title of invention Process for manufacturing foamed metal 2, Patent Detailed description of the invention (industrial application field) The present invention relates to a method for manufacturing a foamed metal in which a large number of closed cells constituting the foamed metal are uniform in size and do not cause internal shrinkage. (Prior art) As a means of obtaining a metal foam, the viscosity of the molten metal is controlled by using a foam material generated by thermal decomposition near the melting point of the metal, and by collecting the generated gas in a melting chamber to form bubbles. A thickening agent is required, and various foams can be obtained by selecting these materials and means. This foamed metal is made up of a large number of closed cells, and is being developed as a new material that is lightweight and has many poor functions such as mechanical and thermal properties. A lot of research has been done on foaming methods, but there are various technical limitations that have prevented any practical use.The reason is that when large-scale materials are produced on an industrial scale, the size of the bubbles becomes uneven. There is also the problem of internal shrinkage occurring when the metal is pseudo-hardened, and therefore it is necessary to solve these problems for practical use. (Objective of the Invention) This invention The present invention has been made to solve the conventional problems such as the above, and provides a method for industrially producing a foamed type A foam that has a large number of homogeneous cells and does not cause internal shrinkage. Structure) The first gist of the present invention is a method for producing a foamed metal consisting of a large number of closed cells by adding a foaming material and a thickening material to molten metal and stirring and covering the mixture. Calcium is used as the viscous material and titanium hydride is used as the foaming material.
After adding 8% by weight and stirring to adjust the viscosity of aluminum, adding 1 to 3% by weight of titanium hydride powder and stirring,
It is made to foam. The second gist of the invention is a method for producing a foamed metal consisting of a large number of closed cells by adding a foaming material and a thickener to molten metal and stirring the mixture, in which the entire mold is heated to a temperature higher than the melting point of the foamed metal. After heating, using aluminum or its alloy as the molten metal, calcium as the thickener, and titanium hydride as the foaming material, add 0.2 to 8% by weight of the above thickener and stir. After adjusting the viscosity, add 1 to 3 weight A% of hydrogenated butane powder and stir to cause foaming. Step C: The mold is sealed with an air outlet for air handling. When the material decomposes due to heat, a large number of bubbles are generated, which expands and releases the air inside the mold to the outside of the mold.The foamed metal fills the metal body inside the mold, causing it to melt and fill. The above-mentioned release [1] is closed with foam metal to make the vJ mold in a sealed state, and in the sealed mold, among the many bubbles, n-
A uniform cell structure is formed by balancing the pressure between the bubbles by increasing the temperature, and then the heating of the mold is stopped and the foamed metal is cooled to avoid solidification. (Example) In FIG. 1, molten aluminum 2 to which a foaming material has been added is charged into a mold 1, and the molten aluminum 2 is stirred by a stirrer 3, and a heater 4 is used to heat the mold 1. is distributed around the mold 1. Figure 1 (B)
As shown in Fig. 2, the molten aluminum 2 expands and becomes the foamed aluminum 20 due to the decomposition of the foam material, and the internal gas pressure (P2) increases. A large number of air bubbles are absorbed when P1 is overcome, but since one side of the mold 1 is exposed to the atmosphere and a free surface is formed,
Each bubble expands arbitrarily depending on its gas pressure, forming a collection of bubbles with extremely irregular sizes and shapes. FIG. 2 is a diagram showing the relationship between such gas pressure and the volume of foamed aluminum. In the same figure, the rest v4Vo of the aluminum at the point when the foaming material is added to the aluminum and stirring is started is until the volume VQ at point B is reached while the gas pressure PA at the point is almost maintained while the foaming material is being added. Expand. In this case, since there is a difference in the addition time of the foaming material, there is also a difference in the amount of gas that has already been generated, and therefore the volume of each bubble becomes uneven. The volume of the foamed aluminum 20 increases from the volume VΩ when the addition of the foaming material ends at point B) to the point C when solidification is completed, and expands to VS while increasing the gas pressure. If foaming is continued in the state shown in FIG. 1(B) according to the conventional method, the foamed aluminum 20 formed will hardly solidify on the free surface in contact with the outside air. This breaks down due to the gas pressure, producing two rotators as shown in FIG. Further, inside the foamed aluminum 20, the size of each bubble 21 is irregular, and large pores 22 are formed near the center where it finally solidifies. aluminum foam 20
When the gas solidifies and is cooled to room temperature by 1A, the pressure decreases as shown in Figure 2 (1) due to the bundle that cools the gas inside each bubble. FIG. 3 is a diagram showing the relationship between aluminum temperature T, elapsed time S, and operations at each stage. In the same figure, point 81 is the melting point of aluminum (M, I)
, ), temperature 7a is higher than the foam material, point 82 is the start of stirring, point 82 is the end of stirring, point a3 is the time to stop heating the mold 1, and from point a1 to a3, the temperature is higher than the melting point. Foaming is performed while maintaining the temperature at Ta. When the foamed aluminum reaches the melting point, solidification is completed at point C, and it is taken out from the mold 1 at point d, when the foamed aluminum reaches room temperature (R, T,). The basic operation in the method according to the present invention is to close the mold 1 at point a2 in FIG. 3, that is, at the point when the foaming material has been added and stirring has been completed. In other words, as shown in Figure 1 (C), M9 preheated to the foaming temperature Ta is attached to the mold 1.
As a result, the mold 1 is sealed with the air outlet 10 formed. A plurality of discharge ports 10 may be formed at appropriate positions. The reason why the lid 9 is preheated is that if the temperature of the lid is low, the free expansion surface of the foaming aluminum will be below the melting point of aluminum, and the bubbles will not grow sufficiently. Further, the relationship between the size of the mold 1 and the amount of molten aluminum 2 charged into the mold 1 is set so that the final product has a predetermined foaming rate. When the pressure P2 of the generated gas in the foamed aluminum 20 becomes larger than the air pressure P3 in the internal space 8 of the closed mold 1, the bubbles in the foamed aluminum 20 expand, and thereby the air in the internal space 8 is released from the discharge port 1o. released from. When the foamed aluminum 20 continues to expand and fills the closed mold 1, the discharge port 1 is opened as shown in FIG. 1 ('D).
0 is closed by the molten aluminum ram 20, and the inside of the mold 1 is completely sealed. Then, the bubbles that have not yet become active by releasing the gas in the foam material every minute form a homogeneous cell structure with a balanced shape and size while maintaining the pressure P2. In other words, if the mold 1 is not sealed, the bubbles near the free surface will expand and become larger than the bubbles in other parts.
However, if the mold 1 is sealed as described above, the expansion is prevented by the pressure of other bubbles, so that the size of the bubbles becomes almost uniform. In Fig. 4, take the swallow 9 which has been mixed with foaming material, stirred and preheated at point A1; At time B when the bubbles are filled, the internal pressure of the bubbles increases to l)C while the volume ■Ω remains constant, forming a uniform collection of bubbles. At this point, the mold is taken out of the furnace (corresponding to A3 in Fig. 3) and cooled to room temperature.As shown in Fig. 5, a homogeneous foamed aluminum 24 with almost the same dimensions as the mold 23 is formed. can get. 4. The shape of the mold used in the F-opening method can be modified in various ways; for example, a spherical mold 5 may be used as shown in FIGS. 6 (Δ) and (B). In the same figure, (
A) shows a state in which molten aluminum 2 is charged into the spherical mold, and (13) shows a state in which the mold 5 is filled with foamed aluminum 20 and the discharge port 10 is closed. In the above example, aluminum was melted at 720° C., and 1.6% calcium was added thereto and stirred to thicken it. The viscosity of aluminum can be adjusted by air blowing without adding a thickener, but this method involves trapping the pyrolysis gas from the foam in the molten metal to create the viscosity necessary to maintain closed cells. This would require a very long period of stirring. On the other hand, if calcium, which has a strong affinity for oxygen, is added as a thickener and stirred, the viscosity can be increased in an extremely short time. In this case, if the amount of calcium added is less than 0.2 pebbles percent, stirring will take a long time, making it extremely inefficient and uneconomical. Further, if the amount is 1% or less to 8-fold, the purpose of thickening can be sufficiently achieved. In addition, while maintaining the molten metal at 720°C after viscosity adjustment, 1.6 weight 16% titanium hydride powder was added as a foaming material.
! One company can produce a homogeneous foam with a porosity of about 90%. In this case, the addition of titanium hydride +M is 1
If it is less than 3% by weight, the generation of bubbles will not be sufficient, and
If it exceeds 11%, bubbles will be generated excessively, requiring long-time stirring or destroying the membrane structure, or the uniform membrane structure will be less than 1%. The appropriate amount of addition (6) is 1 to 3% by weight. (Effects of the invention) As explained above, this invention uses aluminum or its alloy as the molten metal, calcium as the thickener, and titanium hydride as the foaming material. , the above-mentioned thickener is 0.2~
After adding 8% by weight and stirring to adjust the viscosity of the aluminum cum, 1 to 3% of titanium hydride powder was added and stirred to foam. A foam with a cell structure consisting of homogeneous cells! ! ! J
It can be manufactured on an industrial scale. In addition, this foam material is lightweight, has high sound absorption +11, and is useful as a new material with high heat insulation effects, mechanical properties, and machinability. 4. Brief description of the drawings Figures 1 (A) to (D) are explanatory diagrams of the steps for implementing this invention, Figure 2 is a pressure-volume diagram of foamed metal according to the conventional method, and Figure 3 is a diagram of the present invention. Fig. 4 is a pressure-volume diagram obtained by the method of the present invention, Fig. 5 is a conceptual diagram of the foamed metal obtained by the method of the present invention, Fig. 6 (A), (B)
) is a schematic explanatory diagram showing an example of an apparatus used in carrying out the present invention, and FIG. 7 is a conceptual diagram of a foamed metal obtained by a conventional method. DESCRIPTION OF SYMBOLS 1... Mold, 2... Molten aluminum, 3... Stirrer, 4... Heater, 9... Lid, 10... Outlet, 20.24... Foamed aluminum, 23... ...Bubbles.

Claims (1)

[Claims] 1. In a method for producing a foamed metal consisting of a large number of closed cells by adding a foaming material and a thickening material to molten metal and stirring the mixture, the entire mold has a temperature equal to or higher than the melting point of the foamed metal. Then, the foaming material starts to foam after the stirring is finished. During the process of bubble growth, the mold is sealed with an air release port, and the foam material decomposes due to the heat and the numerous bubbles expand. By doing this, the air inside the mold is released to the outside of the mold, and the foamed metal fills the entire inside of the mold, and the molten and filled foamed metal closes the above-mentioned outlet and makes the mold hermetically sealed. A foamed metal characterized in that a uniform cell structure is formed by increasing the internal pressure of a large number of cells in a mold to balance the pressure between the cells, and then the heating of the mold is stopped to cool and solidify the foamed metal. manufacturing method. 2. Using aluminum or its alloy as the molten metal, calcium as the thickener, and titanium hydride as the foaming material, add 0.2 to 8% by weight of the above thickener and stir to adjust the viscosity of the aluminum, Titanium hydride powder 1-3
2. The method for producing a foamed metal according to claim 1, wherein the foamed metal is foamed by adding % by weight and stirring.