KR20210038106A - Manufacturing method for metal foam - Google Patents

Abstract

The present invention relates to a method of manufacturing a metal foam. The metal foam manufacturing method of the present invention has the advantage of being able to quickly manufacture a metal foam having excellent porosity, material properties, etc. The present invention includes a step of sintering a green structure.

Description

Manufacturing method for metal foam {Manufacturing method for metal foam}

The present application relates to a method of manufacturing a metal foam.

Metal foam has a variety of useful properties such as light weight, energy absorption, heat insulation, fire resistance, or eco-friendliness. Accordingly, the metal foam can be applied to various fields including lightweight structures, transport machinery, building materials or energy absorbing devices. In addition, metal foam not only has a high specific surface area, but can further improve the flow of fluids or electrons such as liquids and gases, so it is applied to substrates for heat exchange devices, catalysts, sensors, actuators, secondary cells, fuel cells, etc. And can be usefully used.

In general, a metal foam is manufactured by forming a metal foam precursor using a slurry containing a metal component and sintering the metal foam precursor. As a method of sintering the metal foam precursor, heat is applied using a heating device such as a furnace or an electromagnetic field is applied to generate an eddy current in a metal component, and Joule heat generated by the resistance of the metal component. ) (Also referred to as “induction heating”) is known. However, in the case of the former, since the process of raising the temperature to a specific temperature and cooling it is necessarily accompanied due to the heat treatment characteristics, there is a problem that it takes for a long time. In the latter case, it can be sintered for a relatively fast time. However, in the latter case, the types of applicable metal components are limited. This is because in the latter case, only metal components that can generate heat by applying an electromagnetic field can be applied. In addition, in the latter case, the type of substrate supporting the metal foam precursor is also limited. In the latter case, it is sintered by heat generation of a metal component, so the material of the substrate must not be easily deformed even by the application of heat.

In the present application, one object of the present application is to provide a method of manufacturing a metal foam having excellent porosity and material properties in a short time without limitation of the type of substrate supporting the applied metal component and the metal foam. It is done.

In the present application, the term metal foam refers to a porous structure containing a metal as a main component. In the above, the use of metal as the main component means that the ratio of the metal or metal alloy based on the total weight of the metal foam is 55% by weight or more, 60% by weight or more, 65% by weight or more, 70% by weight or more, 75% by weight or more, 80 It means a case of at least 85% by weight, at least 90% by weight, or at least 95% by weight. The upper limit of the proportion of the metal contained as the main component is not particularly limited, and may be, for example, 100% by weight.

Among the physical properties mentioned in the present application, when the measurement temperature affects the property, the properties are measured at room temperature, unless otherwise specified. The term room temperature is a natural temperature that is not heated or reduced, and may mean, for example, any temperature within the range of about 10 °C to 30 °C, a temperature of about 23 °C or about 25 °C. .

In the present application, the unit “parts by weight” refers to the relative weight of a component with respect to other components, and does not mean an absolute value such as g, kg, or lb.

The present application relates to a method of manufacturing a metal foam. The method of manufacturing the metal foam of the present application includes at least sintering the green structure.

In the present application, the green structure is a structure before undergoing a process performed to form a metal foam such as sintering, that is, a structure before the metal foam is generated, and is sometimes referred to as a metal foam precursor. In addition, the green structure, even if it is also referred to as a porous metal foam precursor or a porous green structure, does not necessarily have to be porous by itself, and if it can finally form a metal foam that is a porous metal structure, for convenience, a porous green structure or It may also be referred to as a porous metal foam precursor.

Meanwhile, when the green structure is a porous structure, the porosity of the green structure may be in the range of 30% to 90%. The porosity of the green structure is, in another example, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, or 80% It may be greater than or equal to 85% or less or 80% or less.

The green structure may be formed using at least a slurry, and the slurry may contain at least a metal component, an aqueous solvent, an organic solvent, and a surfactant.

In the present application, since a specific sintering method is adopted, there is an advantage that the type of metal component applied to the slurry is not particularly limited. For example, as the metal component, a component including a certain metal or an alloy containing the metal can be applied. As a non-limiting example, the metal includes copper, molybdenum, iron, nickel, cobalt, silver, platinum, gold, aluminum, chromium, indium, tin powder, magnesium, phosphorus, zinc, manganese, or a combination thereof. Can be applied. In the above, the alloy containing the metal may mean two or more types of alloys among the exemplified metals.

In one example, the metal component forming the green structure may be in the form of a powder. For example, the metal or alloys thereof in the metal component may have an average particle diameter in the range of about 1 μm to 100 μm. The average particle diameter, in another example, may be 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, 9 μm or more, or 10 μm or more, and 95 μm or less , 90 μm or less, 85 μm or less, 80 μm or less, 75 μm or less, 70 μm or less, 65 μm or less, 60 μm or less, 55 μm or less, 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 It may be μm or less, 25 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less. The average particle diameter may be selected in an appropriate range in consideration of the shape of the desired metal foam, for example, the thickness or porosity of the metal foam, and this is not particularly limited. In the present application, the average particle diameter of the metal component may be obtained by a known particle size analysis method, and for example, the average particle diameter may be a so-called D50 particle diameter.

The shape of the metal powder is also selected in consideration of a desired porosity or pore size, and is not particularly limited. For example, when the metal component is in a powder form, the metal component in the powder form is dentritic. It may be a component of or a plate-type component.

The ratio of the metal component in the slurry is not particularly limited, and may be selected in consideration of a desired degree or process efficiency. In one example, the proportion of the metal component in the slurry may be about 0.5% to 95% by weight, but is not limited thereto. The proportion of the metal component, in another example, 1% by weight or more, 5% by weight or more, 10% by weight or more, 15% by weight or more, 20% by weight or more, 25% by weight or more, 30% by weight or more, 35% by weight or more , 40% by weight or more, 45% by weight or more, 50% by weight or more, or 55% by weight or more, and 90% by weight or less, 85% by weight or less, 80% by weight or less, 75% by weight or less, 70% by weight or less, 65% by weight % Or less, 60% by weight or less, and 55% by weight or less.

As described above, the slurry forming the green structure contains the metal component, an aqueous solvent, an organic solvent, and a surfactant.

In the slurry, by appropriately selecting and/or controlling the ratio and type of the aqueous solvent, organic solvent, and surfactant, a fine emulsion (droplet, emulsion) may be formed in the green structure, and this emulsion is a metal The porosity properties of the foam can be determined. For example, as described later, in the process of forming a green structure by drying the slurry, a component having a greater vapor pressure is evaporated due to the difference in vapor pressure between the organic solvent and the aqueous solvent, thereby determining the pore characteristics of the metal foam. I can.

As the aqueous solvent, water or other polar solvents may be used, and water may be used as a representative example. The slurry may contain an aqueous solvent in a ratio of about 10 parts by weight to 1500 parts by weight based on 100 parts by weight of the metal component. In another example, the ratio of the aqueous solvent is 15 parts by weight or more, 20 parts by weight or more, 25 parts by weight or more, 30 parts by weight or more, 35 parts by weight or more, 40 parts by weight or more, 45 parts by weight or more, 50 parts by weight or more, It may be 55 parts by weight or more or 60 parts by weight or more, and 1400 parts by weight or less, 1300 parts by weight or less, 1200 parts by weight or less, 1100 parts by weight or less, 1000 parts by weight or less, 900 parts by weight or less, 800 parts by weight or less, 700 parts by weight Or less, 600 parts by weight or less, 500 parts by weight or less, 400 parts by weight or less, 300 parts by weight or less, 200 parts by weight or less, 100 parts by weight or less, 90 parts by weight or less, 80 parts by weight or less, 70 parts by weight or less, or 65 parts by weight It can be below.

The type of organic solvent applied to the slurry is not particularly limited. As an organic solvent, an emulsion can be formed through the action of the above-described aqueous solvent and a surfactant to be described later, and can be foamed in a drying process by vaporization by having an appropriate vapor pressure, and components of the slurry, such as the above. An appropriate component can be applied in consideration of solubility with a metal component or a binder to be described later. As such an organic solvent, for example, any one of n-pentane, neopentane, hexane, cyclohexane, isohexane, heptane, isoheptane, octane, toluene, benzene or isopropyl ether, or two of these The above combination may be applied, but is not limited thereto.

The ratio of the organic solvent in the slurry is also not particularly limited. For example, the slurry may contain an organic solvent in a ratio within the range of 0.1 parts by weight to 10 parts by weight based on 100 parts by weight of the metal component. The ratio of the organic solvent, in another example, may be 0.2 parts by weight or more, 0.3 parts by weight or more, 0.4 parts by weight or more, 0.5 parts by weight or more, or 0.6 parts by weight or more, and 7 parts by weight or less, 5 parts by weight or less, 3 parts by weight It may be less than or equal to 1 part by weight.

A surfactant is included in the slurry to form a suitable fine emulsion in the green structure, and/or to form conditions suitable for vaporization described above.

As the surfactant, as long as the emulsion can be formed in consideration of the types of the aqueous solvent and organic solvent to be applied, various types of surfactants can be applied without any particular limitation. For example, as the surfactant, any one selected from the group consisting of an amphoteric surfactant, a nonionic surfactant, and an anionic surfactant, or a mixture of two or more of the above may be applied. In some cases, even when any one type of surfactant among amphoteric surfactant, nonionic surfactant, and anionic surfactant is used, a mixture of two or more surfactants having different structures may be applied within one type.

The anionic surfactant may mean a surfactant in which a moiety exhibiting surface activity is an anion. Examples of anionic surfactants include carboxylate compounds, sulfate compounds, isethionate compounds, sulfosuccinate compounds, taurate compounds, and/or glutamate. (glutamate) compounds may be applied.

In order to secure appropriate pore characteristics, the anionic surfactant has a hydrocarbon chain moiety of 4 or more, 8 or more, or 10 or more carbon atoms, or has an oxyalkylene repeating unit or an alkyleneoxy repeating unit, and the number of repeating units is Surfactants within the range of 3 to 20 can be selected. In the above, the number of carbon atoms in the hydrocarbon chain portion may be approximately 30 or less, 26 or less, or 22 or less in other examples. Examples of the hydrocarbon chain moiety include an alkyl group, an alkenyl group, an alkynyl group, an alkylene group, an alkenylene group, and/or an alkynylene group.

As the anionic surfactant, a compound represented by the following Formula 6 may be exemplified.

[Formula 6]

In Formula 6, P is an alkyl group having 8 to 30 carbon atoms or an alkoxy group having 8 to 30 carbon atoms, and T is a single bond, an oxyalkylene repeating unit, an alkyleneoxy repeating unit, -C(=O)OL ₁₀ -or -OC (= O) -L, and _10, wherein L ₁₀ is an alkylene group or a single bond, Q is -CO ₂ ^- M ⁺ or a ^- SO ₃ - and M ^+, wherein M ⁺ can be an alkali metal ion or an ammonium cation .

In Formula 6, P is an alkyl group having 8 to 26 carbon atoms, 8 to 22 carbon atoms, 8 to 18 carbon atoms, or 8 to 14 carbon atoms, or 8 to 26 carbon atoms, 8 to 22 carbon atoms, 8 to 18 carbon atoms, or 8 to 14 carbon atoms. It may be an alkoxy group of. The alkyl group or alkoxy group may have a linear or branched structure. The alkyl group or the alkoxy group may be optionally substituted with one or more substituents.

In Formula 6, when T is an oxyalkylene repeating unit or an alkyleneoxy repeating unit, the repeating unit may have a structure _{of -(-OA-) n} -or -(-AO-) _{n -.} In the above, A is an alkylene group, and in this case, the alkylene group may be a linear or branched alkylene group having 1 to 4 carbon atoms. The number of oxyalkylene repeating units or alkyleneoxy repeating units, that _{is, in the structure of -(-OA-) n} -or -(-AO-) _n -, n may be in the range of 3 to 20 in one example. have. In the above, the alkylene group may be optionally substituted with one or more substituents.

In Formula 6, when T is -C(=O)OL ₁₀ -or -OC(=O)-L ₁₀ , the L ₁₀ may be an alkylene group or a single bond, wherein the alkylene group has 1 to 4 carbon atoms. It may be a linear or branched alkylene group. Such an alkylene group may be optionally substituted with one or more substituents.

Q of formula (6) above is an anionic or ionic portion of the surface active agent, for example, a carboxylate anion (CO ₂ ^-) moiety or sulfate anions (SO ₃ ^-) It may be a site or a salt site thereof. For example, the Q is -CO ₂ ^- M ⁺ or a ^- SO ₃ - may be represented by M ^+. In the above, M ⁺ may be an alkali metal ion or an ammonium cation. In the above, the alkali metal ions may be lithium ions, sodium ions, potassium ions, and the like, and the ammonium ions may be tetraalkylammonium ions. In the above, the alkyl group of the tetraalkylammonium ion may be a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, and optionally one or more It may be substituted with a substituent.

The pH of the anionic surfactant may be adjusted within a range of, for example, about 6 to 12 for forming an appropriate microemulsion in the green structure and/or controlling the vaporization described above. Within this pH range, suitable pore properties can be implemented in the metal foam.

The pH of the surfactant can be controlled during the preparation of the surfactant. For example, in an example, the surfactant of Formula 6 may be formed by applying a fatty acid such as lauric acid, myristic acid, palmitic acid, oleic acid, linoleic acid, stearic acid, behenic acid, and an alkali metal salt. In this process, it is possible to adjust the pH by adjusting the amount of alkali metal salt applied.

Nonionic surfactant, as known, may mean a surfactant that is not separated into ions. As the nonionic surfactant, a compound represented by any one of the following formulas 2 to 5 may be used.

[Formula 2]

In Formula 2, m is a number within the range of 1 to 3, L ₄ is an alkylene group, R ₆ is a hydrogen, an alkyl group or an alkoxy group, and the sum of the number of carbon atoms in _{L 4} and R _{6 is within the range of 5 to 20} to be.

Surfactants of the above formula are known as so-called alkyl polyglucoside compounds, and among the alkyl polyglucoside compounds, the compound of formula 2 may be advantageous in implementing particularly suitable pore properties.

[Formula 3]

In Formula 3, R ₇ and R ₈ are each independently hydrogen, an alkyl group or an alkoxy group, L ₅ and L ₆ are each an alkylene group, and R ₉ may be hydrogen, an alkyl group, an alkoxy group or a hydroxy group.

In the above structure, _{the sum of the number of carbon atoms present in R 7} and L ₅ may be a number within the range of 8 to 20. That is, the sum of the number of carbon atoms in the alkyl group or alkoxy group of _{R 7 and the number of carbon atoms in the alkylene group of L 5} may be within the above range, and the sum of the number of carbons may be in the range of about 10 to 15 in another example. . The alkyl group or alkoxy group of _{R 7 and the alkylene group of L 5} may have a linear or branched structure.

In the above structure, _{the sum of the number of carbon atoms present in R 8} , R ₉ and L ₆ may be a number within the range of 2 to 10. That is, the sum of the number of carbon atoms in the alkyl group or alkoxy group of _{R 8} and R _{9 and the number of carbon atoms in the alkylene group of L 6 may be within the above range.}

In addition to the alkyl group or alkoxy group of _{R 7 and the alkylene group of L 5,} the alkyl group, alkoxy group or alkylene group of Formula 3 has 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 carbon number. It may be an alkyl group of to 4, an alkoxy group, or an alkylene group, which may be linear, branched, or cyclic, and may be optionally substituted with one or more substituents.

[Formula 4]

In Formula 4, R ₁₀ to R ₁₂ may each independently represent hydrogen, an alkyl group or an alkoxy group, and L ₇ may be an alkylene group.

In the above structure, _{the sum of the number of carbon atoms present in R 10} and L ₇ may be a number within the range of 8 to 20. That is, the sum of the number of carbon atoms in the alkyl group or alkoxy group of _{R 10 and the number of carbon atoms in the alkylene group of L 7} may be within the above range, and the sum of the number of carbons may be in the range of about 10 to 15 in another example. . The alkyl group or alkoxy group of _{R 10 and the alkylene group of L 7} may have a linear or branched structure.

In the above structure, _{the sum of the number of carbon atoms present in R 11} and R ₁₂ may be a number within the range of 0 to 8. That is, if present, the sum of the number of carbon atoms present in the alkyl group or alkoxy group of _{R 11} and R _{12 may be 8 or less, and when both R 11} and R ₁₂ are hydrogen, the number of carbons is 0.

The _{alkyl group or alkoxy group of R 11} and R _{12 may be} an alkyl group or alkoxy group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, which is a straight chain, branched chain or ring Type, and may be optionally substituted with one or more substituents.

[Formula 5]

In Formula 5, R ₁ to R ₃ are each independently hydrogen, an alkyl group, a hydroxy group, or an alkoxy group, n, p and q are each independently a number within the range of 10 to 20, and a to f have a total of 0 to 40 It may be a number within the range of.

In the above, the sum of a to f may be 4 or more, 8 or more, 12 or more, 16 or more, 20 or more, 24 or more, 28 or more, or 36 or less in another example.

The compound of Formula 5 is a formula for a so-called ethoxylated castor oil, wherein the sum of a to f refers to the number of moles added of ethylene oxide units in the oil.

The amphoteric surfactant is a surfactant having an anionic moiety and a cationic moiety at the same time, and, for example, the compound of Formula 1 may be applied.

[Formula 1]

In Formula 1, R ₁ to R ₄ are each independently hydrogen, an alkyl group, an alkoxy group, or -NR ₅ -, L ₁ to L ₃ are each independently a single bond or an alkylene group, and X is -C(=O)- NR ₆ - or a single bond, Y is ^{_{-CO 2 -, -CO 2 - M}} +, -SO ₃ ^- or-SO ₃ ^- M ⁺ , q is 0 or 1, and R ₅ and R ₆ are each independently hydrogen, an alkyl group or an alkoxy group, and M ⁺ may be an alkali metal ion or an ammonium cation have.

In the above structure, _{the sum of the number of carbon atoms present in R 4} and L ₁ may be a number within the range of 8 to 20. That is, the sum of the number of carbon atoms in the alkyl group or alkoxy group of _{R 4 and the number of carbon atoms in the alkylene group of L 1} may be within the above range, and the sum of the number of carbons is about 8 to 15 or about 10 to 15 in another example. It may be within the range of. The alkyl group or alkoxy group of _{R 4 and the alkylene group of L 1} may have a linear or branched structure.

Another alkyl group, alkoxy group or alkylene group present in Formula 1 may be an alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms or 1 to 4 carbon atoms, an alkoxy group or an alkylene group, It may be straight chain, branched chain or cyclic, and may be optionally substituted with one or more substituents.

Y of the formula (1) or a salt thereof or a carboxylate-based anionic site, a sulfate-based anion or a salt site, for _{^{example, -CO 2 -, -CO 2 -}} M +, -SO 3 - or ^- SO ₃ - M Can be ⁺

When Y in Formula 1 is a carboxylate-based anion or a salt moiety thereof, R ₁ to R ₄ in Formula 1 are each independently hydrogen, an alkyl group or an alkoxy group, and L ₁ to L ₃ are each independently a single bond or an alkylene group, X is -C (= O) -NR ₅ - or a single bond, Y is ^{_{-CO 2 -, -CO 2 - M}} +, -SO 3 - or ^- SO ₃ - M a ^+, q is 0 or 1, R ₅ is hydrogen, an alkyl group or an alkoxy group, and M ⁺ may be an alkali metal ion or an ammonium cation. In the above, the alkali metal ions may be lithium ions, sodium ions, potassium ions, and the like, and the ammonium ions may be tetraalkylammonium ions. In the above, the alkyl group of the tetraalkylammonium ion may be a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, and optionally one or more It may be substituted with a substituent.

In Formula 1, q is 0 or 1, and when q is 0, L ₂ and L ₃ are directly connected.

As the surfactant, any one type of anionic, nonionic, or amphoteric surfactant of each of the above-mentioned formulas may be used alone, or two or more surfactants may be used in combination.

In addition, as surfactants of each of the above formulas, two or more surfactants having different specific structures may be mixed and used within the scope of the formula.

Examples of suitable surfactant mixing include mixing of anionic surfactant and nonionic surfactant or mixing of anionic surfactant and amphoteric surfactant, or mixing of nonionic surfactant and amphoteric surfactant, or of the three surfactants. Mixing and the like can be exemplified.

In such mixing, the mixing ratio can be appropriately controlled. For example, in the case of mixing in which an anionic surfactant is included, the total pH may be in the above-described range, that is, in the range of 6 to 12, or may be mixed so as to be at the level of approximately 6 to 8 as a neutral level. In addition, in the case of mixing containing an anionic surfactant, the mixing ratio may be determined such that approximately 10 to 50 parts by weight of another surfactant is present relative to 100 parts by weight of the anionic surfactant.

The ratio of the surfactant in the slurry can also be appropriately adjusted. The slurry may contain the surfactant in a ratio within a range of 10 parts by weight to 1000 parts by weight based on 100 parts by weight of the organic solvent. The ratio, in another example, 20 parts by weight or more, 30 parts by weight or more, 40 parts by weight or more, 50 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, 80 parts by weight or more, 90 parts by weight or more, or 100 parts by weight It may be at least 900 parts by weight, 800 parts by weight or less, 700 parts by weight or less, 600 parts by weight or less, 500 parts by weight or less, 400 parts by weight or less, 300 parts by weight or less, 200 parts by weight or less, or 100 parts by weight or less. have. Under this ratio, it is possible to effectively manufacture a metal foam having a desired pore property.

In one example, the slurry may further include necessary ingredients in addition to the above ingredients. For example, the slurry may further include a binder. The slurry may be a component for forming pores in the metal foam finally formed by serving as a pore holder by including a binder, or it may serve to support the metal component contained in the slurry so that it does not scatter. have. As the binder, without particular limitation, for example, it may be appropriately selected according to the type of a water-soluble binder or a metal component and/or an organic solvent applied at the time of preparation of the slurry. For example, as the binder, alkyl cellulose having an alkyl group having 1 to 8 carbon atoms such as methyl cellulose or ethyl cellulose, hydroxyalkyl cellulose having 1 to 8 carbon atoms such as hydroxypropyl cellulose, polypropylene carbonate or polyethylene carbonate, etc. A polyalkylene carbonate having an alkylene unit having 1 to 8 carbon atoms, or a polyvinyl alcohol-based binder such as polyvinyl alcohol or polyvinyl acetate (hereinafter may be referred to as a polyvinyl alcohol compound), etc. may be exemplified. , But is not limited thereto.

The ratio of the binder is not particularly limited, and may be appropriately adjusted according to the desired pore characteristics. For example, the slurry may contain the binder in a ratio of 50 parts by weight to 2000 parts by weight based on 100 parts by weight of the organic solvent. The ratio is, in another example, 100 parts by weight or more, 150 parts by weight or more, 200 parts by weight or more, 250 parts by weight or more, 300 parts by weight or more, 350 parts by weight or more, 400 parts by weight or more, 450 parts by weight or more, 500 parts by weight Parts by weight or more, 550 parts by weight or more, 600 parts by weight or more, 650 parts by weight or more, 700 parts by weight or more, 750 parts by weight or more, 800 parts by weight or more, 850 parts by weight or more, 900 parts by weight or more, 950 parts by weight or more, 1000 parts by weight May be at least 1050 parts by weight, 1100 parts by weight or more, 1150 parts by weight or more, 1200 parts by weight or more, 1250 parts by weight or more, and 1900 parts by weight or less, 1800 parts by weight or less, 1700 parts by weight or less, 1600 parts by weight or less, It may be 1500 parts by weight or less, 1400 parts by weight or less, 1300 parts by weight or less, or 1280 parts by weight or less.

The slurry may further contain other known additives. Examples of such additives include plasticizers. As in the present application, a plasticizer may be applied to the slurry formed of a metal foam by applying a foaming method, and in this application, a plasticizer may be included in the slurry in an appropriate amount. Examples of such plasticizers include polyhydric alcohols such as ethylene glycol, ether compounds such as tris(2-ethylhexyl)phosphate, or ester compounds such as bis(2-ethylhexyl)phthalate.

The ratio of the plasticizer may also be appropriately adjusted within a range to ensure desired pore characteristics. The slurry may contain the plasticizer in a ratio of 10 parts by weight to 1000 parts by weight based on 100 parts by weight of the organic solvent. The ratio may be, in another example, 50 parts by weight or more, 100 parts by weight or more, 150 parts by weight or more, 200 parts by weight or more, 250 parts by weight or more, 300 parts by weight or more, or 350 parts by weight or more, and 900 parts by weight or less, It may be 800 parts by weight or less, 700 parts by weight or less, 600 parts by weight or less, 500 parts by weight or less, or 400 parts by weight or less.

The method of forming the green structure using the above slurry is not particularly limited. In the field of manufacturing a metal foam, various methods for forming a green structure are known, and all of these methods can be applied in the present application. For example, the green structure may be manufactured by maintaining the slurry in an appropriate template, or by applying heat to dry it, or by applying the slurry to a substrate and then applying heat thereto. It can also be prepared in a manner that includes a drying process. In particular, through a drying process, the organic solvent contained in the slurry is evaporated, and since such an organic solvent forms fine droplets in the slurry, pores of approximately the same size as the fine droplets may be formed in the green structure. , These pores can determine the pore characteristics of the metal foam.

In the above, a method of applying the slurry is not particularly limited, and a known application method such as dip coating, die coating, and bar coating may be applied.

In addition, the drying may be performed at a temperature higher than the boiling point of the organic solvent, but within a range in which the frame or substrate supporting the slurry is not damaged. For example, the drying may be performed within a temperature range of 100° C. or less. The temperature may be 30 ℃ or more, 35 ℃ or more, 40 ℃ or more in other examples, 95 ℃ or less, 90 ℃ or less, 85 ℃ or less, 80 ℃ or less, 75 ℃ or less, 70 ℃ or less, 65 ℃ or less, 60 ℃ It may be less than or equal to or less than 55°C. The time of the drying process may be selected in consideration of the desired porosity of the green structure, and may be in the range of approximately 1 minute to 1 hour, but is not limited thereto.

In the present application, a specific sintering method described later is adopted, and since the method is configured so that sintering of the green structure can be performed at a relatively low temperature, the substrate (or frame) on which the slurry is applied to form the green structure The kind has an advantage that is not particularly limited. Therefore, in the conventional induction heating or heating method using a furnace, etc., the substrate or frame is limited to a metal substrate that is not damaged even at a high temperature, but in this application, in addition to the above metals, PET (polyethylene therephthalate), COP (cycloolefin polymer), A substrate made of a polymer such as PC (polycarbonate) or a carbon-based substrate such as graphite foil may be applied as a frame.

The shape of the green structure is not particularly limited as it is determined according to the desired metal foam. In one example, the green structure may be in the form of a film or a sheet. For example, when the green structure is in the form of a film or sheet, the thickness may be in the range of 50 μm to 500 μm. By controlling the thickness in this range, it is possible to manufacture a metal foam having suitable properties according to the purpose. In addition, the thickness of the green structure may be determined according to the constituent components of the slurry, and in particular, in the present application, it may be determined according to the size of the microemulsion formed by the aqueous solvent, organic solvent, and surfactant included in the slurry. It may have a generally thicker thickness than a green structure formed of a slurry mainly containing a binder and an organic solvent. In another example, the thickness may be 60 μm or more, 70 μm or more, 80 μm or more, 90 μm or more, 100 μm or more, 110 μm or more, 120 μm or more, 130 μm or more, 140 μm or more, or 150 μm or more, and 450 It may be μm or less, 400 μm or less, 350 μm or less, 300 μm or less, 250 μm or less, 200 μm or less, 190 μm or less, 180 μm or less, 170 μm or less, or 160 μm or less.

In the present application, a metal foam is manufactured by sintering the green structure described above. In the present application, as a method for such sintering, a method of light irradiation (hereinafter, also referred to as optical sintering) is applied, rather than simple heating using a conventional furnace or induction heating by application of an electromagnetic field. . In this way, when the light sintering method is applied, a metal foam having excellent material properties (porosity, strength, thin thickness, etc.) can be produced in a short time, and the metal component or metal foam constituting the metal foam There is an advantage that the frame or substrate for supporting the precursor (or green precursor) is not limited to a specific component or material.

The method of irradiating light to the green structure is not particularly limited. In the present application, the green structure may be sintered by irradiating various types of light such as ultraviolet rays, electromagnetic rays, infrared rays, or electron beams with the light. For example, the sintering may be performed by irradiating the green structure with pulsed electromagnetic radiation. In the above, the pulsed electromagnetic radiation may mean radiation that is irradiated in the form of a pulse and falls within a range of an electromagnetic wave wavelength. Accordingly, in the present application, a method of sintering the green structure by irradiating light having a wavelength range of 200 nm to 1500 nm in a pulse form may be applied. If this method is applied, there may be an advantage in that sintering of the metal component applied to the metal foam can be sufficiently performed without large heat generation within a short time.

The irradiation condition of the pulsed electromagnetic radiation may be appropriately adjusted without limitation in order to achieve the above-described object.

In one example, the pulse width of the pulsed electromagnetic radiation may be in the range of 100 μs to 10 ms. The pulse width, in another example, may be 0.5 ms or more, 1 ms or more, 1.5 ms or more, or 2 ms or more, and may be 9 ms or less, 8 ms or less, 7 ms or less, 6 ms or less, 5 ms or less, or 4 ms or less. I can. In the above, the meaning of the pulse width is well known in the industry, and may mean, for example, a time interval of a single pulse.

In one example, the pulse rate of the pulsed electromagnetic radiation may be in the range of 0.1 Hz to 1 kHz. The pulse rate, in another example, may be 0.5 Hz or more, 1 Hz or more, 1.5 Hz or more, 2 Hz or more, and 500 Hz or less, 100 Hz or less, 50 Hz or less, 30 Hz or less, 10 Hz or less, 5 Hz or less Or 3 Hz or less. In the above, the pulse rate may mean a time taken from a single pulse to the next pulse, that is, a period in which a pulse is repeated when electromagnetic radiation is irradiated in a pulse form.

In one example, the voltage of the pulsed electromagnetic radiation may be in the range of 350 V to 500 V. The voltage, in another example, may be 360 V or more, 370 V or more, 380 V or more, 390 V or more, or 400 V or more, and 490 V or less, 480 V or less, 470 V or less, 460 V or less, 450 V or less, It may be 440 V or less, 430 V or less, 420 V or less, 410 V or less, or 400 V or less.

In one example, the pulse number of the pulsed electromagnetic radiation may be in the range of 1 to 100. The number of pulses, in another example, may be 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, or 10 or more, and 90 or less, 80 or less, 70 or less, 60 or less, It may be 50 or less, 40 or less, 30 or less, 20 or less, or 10 or less. In the above, the number of pulses may mean the number of times the electromagnetic radiation is irradiated in the form of a pulse when the pulsed electromagnetic radiation is irradiated during the light sintering process.

In one example, the energy of the pulsed electromagnetic radiation may be in the range of ^{0.1 J/cm 2} to 100 J/cm ^2. The energy, in another example, may be 0.5 J/cm ² or more, 1 J/cm ² or more, 1.5 J/cm ² or more, 2 J/cm ² or more, or 2.5 J/cm ^{2 or} more, and 90 J/cm ² Or less, 80 J/cm ² or less, 70 J/cm ² or less, 60 J/cm ² or less, 50 J/cm ² or less, 40 J/cm ² or less, 30 J/cm ² or less, 20 J/cm ² or less , 10 J/cm ² or less or 7 J/cm ² or less.

As described above, in the case of manufacturing a metal foam by sintering the green structure through irradiation of light, there is an advantage that the metal foam can be formed in a short time. Accordingly, the light, specifically, the irradiation time of the pulsed electromagnetic radiation may be in the range of, for example, 1 second to 30 minutes. The irradiation time, in another example, may be 30 seconds or more, 1 minute or more, 3 minutes or more, or 5 minutes or more, and may be 20 minutes or less, 10 minutes or less, or 5 minutes or less.

The above-mentioned conditions of light irradiation, for example, the number of pulses, energy of radiation, and pulse rate may be appropriately changed in consideration of the type of metal component to be applied, the type of frame or substrate supporting the green structure, and the like.

In addition, the light irradiation may be performed in the presence of an inert gas such as a specific atmospheric atmosphere, for example, argon or a mixed gas of argon and nitrogen.

In one example, the sintering may be performed only through the above-described light irradiation, and appropriate heat may be applied together with the light irradiation, or may be performed while applying an electromagnetic field or the like.

This application also relates to a metal foam. The metal foam may be manufactured by the above-described method.

As described above, a metal foam may be formed by sintering the green structure. As described above, when the green structure is in the form of a film or a sheet, the metal foam may also be in the form of a film or a sheet like the green structure. In addition, the thickness of the metal foam may be the same as the above-described green structure, or even if different, the difference may be very slight. The difference (thickness of green structure-thickness of metal foam) is, for example, more than 0 μm and less than 30 μm, less than 25 μm, less than 20 μm, less than 15 μm, less than 10 μm, less than 5 μm, or less than 1 μm. It may be within range. By controlling the thickness in this range, it is possible to manufacture a metal foam having suitable properties according to the purpose.

The metal foam may have a porosity within a specific range. For example, the porosity of the metal foam manufactured by the above method may be 99% or less. In another example, the porosity may be 95% or less, 90% or less, or 85% or less, and may be 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, or 70% or more. have. The porosity can be calculated in a known manner by calculating the density of metal foam.

In addition, the metal foam may have an average size of pores constituting it within a specific range. For example, the average size of the pores of the metal foam may be adjusted according to the composition of the slurry, the thickness of the metal precursor, and sintering conditions. The average pore size of the metal foam may be, for example, in the range of 10 μm to 100 μm. In the present application, since it is formed by droplets formed by an aqueous solvent, an organic solvent, and a surfactant in a manner of forming pores of the metal foam, the pore size may be larger than that of the metal foam manufactured without applying this method.

Such a metal foam can be applied to various applications requiring a porous metal structure. In particular, according to the method of the present application, it is possible to manufacture a metal foam in the form of a film or a sheet having a desired level of porosity, pore size and thickness, etc., as described above, so that the use of the metal foam can be expanded compared to the existing one. There are also benefits that can be done.

The metal foam manufacturing method of the present application has the advantage of being able to manufacture a metal foam having excellent porosity and material properties in a short time without limitation of the type of substrate supporting the metal component and the metal foam to be applied. .

1 and 2 are SEM photographs of the green structure of the embodiment.
3 and 4 are SEM photographs of the metal foam of the embodiment.
5 and 6 are SEM photographs of a metal foam of a comparative example.

The present application will be described in detail through the following examples, but the scope of the present application is not limited by the following examples.

[How to measure]

Porosity measurement

The porosity of the green structure or metal foam in Examples and Comparative Examples was measured by inverting the size of the manufactured metal foam specimen and the weight of afleh alc.

SEM photo shoot

Cross-sectional photographs of green structures or metal foams in Examples and Comparative Examples were taken using a scanning electron microscope (SEM), JSM7610F, JEOL.

[Production Example]

Example

Components applied in the examples are as follows:

<Applicable ingredients>

Metal component: plate-shaped copper powder with an average particle diameter (D50 particle diameter) of about 10 μm or less

Aqueous solvent: water

Organic Solvent: Hexane

Binder: 5.2:1.8 (hydroxypropyl cellulose: methyl cellulose) weight ratio mixture of hydroxypropyl cellulose and methyl cellulose

Surfactant: lauramine oxide, a nonionic surfactant

Plasticizer: Ethylene glycol

Green structure

In an aqueous solvent, a metal component, an organic solvent, a binder, a surfactant, and a plasticizer are mixed in a weight ratio of 35:57.7:0.4:5.1:0.4:1.4 (aqueous solvent: metal component: organic solvent: binder: surfactant: plasticizer). Thus, a slurry was prepared.

The slurry was coated on a known release film to a thickness of about 175 μm, and dried to prepare a green structure having a thickness of about 170 μm and a free-standing green structure. The porosity of the green structure was about 85%. FIG. 1 is an SEM photograph of the green structure, and FIG. 2 is a photograph magnified 4 times of the photograph of FIG. 1.

Metal foam

The green structure was photosintered to prepare a film-type metal foam. Photosintering was specifically performed while purging with hydrogen/argon gas and irradiating pulsed electromagnetic xenon radiation to the green structure. PulseForge 2300 (Novacentrix) was applied as an irradiation device, and the irradiation conditions of pulsed electromagnetic radiation are as follows:

Applied voltage: about 400 V

Pulse width: about 4 ms

Pulse rate: about 2.3 Hz

Number of pulses: 10

Energy: about 3.2 J/cm ²

Irradiation time: about 4 minutes

The SEM photograph of the metal foam manufactured by the above method is shown in FIG. 3, and the photograph of FIG. 3 is enlarged 6 times in FIG. 4. The thickness of the metal foam was about 170 μm, and the porosity was about 82%. It can be seen that by the above method, a metal foam having a porosity equivalent to that of the examples to be described later can be manufactured in a shorter time.

Comparative example

Metal foam

In order that the green structure prepared in the example was maintained in a hydrogen/argon gas atmosphere and a temperature of about 1000° C. for 2 hours, sintering was performed by applying an external heat source in an electric furnace (furnace) to prepare a film-shaped metal foam. The metal foam had a porosity of about 85%, and its thickness was about 140 μm. The SEM image of the metal foam is shown in FIG. 5, and a double enlarged view of FIG. 5 is shown in FIG. 6.

Claims (20)

Metal foam comprising the step of sintering the green structure by irradiating light to a green structure formed by using a slurry containing a metal or a metal component including an alloy containing the metal, an aqueous solvent, an organic solvent, and a surfactant Manufacturing method. The method of claim 1, wherein the green structure is manufactured by applying the slurry on a substrate and then drying it. The method of claim 2, wherein the substrate is a metal substrate, a carbon-based substrate, or a polymer substrate. The method of claim 1, wherein the metal is copper, molybdenum, iron, nickel, cobalt, silver, platinum, gold, aluminum, chromium, indium, tin powder, magnesium, phosphorus, zinc, manganese, or a combination thereof. Manufacturing method. The method of claim 1, wherein the metal component has an average particle diameter in the range of 1 μm to 100 μm. The method of claim 1, wherein the organic solvent is n-pentane, neopentane, hexane, cyclohexane, isohexane, heptane, isoheptane, octane, toluene, benzene or isopropyl ether. The method of claim 1, wherein the surfactant is at least one of a nonionic surfactant, an amphoteric surfactant, and an anionic surfactant. The method of claim 1, wherein the slurry further comprises a binder. The method of claim 1, wherein the slurry contains a metal component in an amount of 45% by weight or more. The method of claim 1, wherein the slurry comprises an organic solvent in a ratio within the range of 0.1 parts by weight to 10 parts by weight based on 100 parts by weight of the metal component. The method of claim 1, wherein the slurry comprises a surfactant in a ratio within the range of 10 parts by weight to 1000 parts by weight based on 100 parts by weight of the organic solvent. The method of claim 9, wherein the slurry comprises a binder in a ratio within the range of 50 parts by weight to 2000 parts by weight based on 100 parts by weight of the organic solvent. The method of claim 1, wherein the irradiation of light is performed by irradiating the green structure with pulsed electromagnetic radiation. 14. The method of claim 13, wherein the pulse width of the pulsed electromagnetic radiation is within a range of 100 μs to 10 ms. 14. The method of claim 13, wherein the pulse rate of the pulsed electromagnetic radiation is in the range of 0.1 Hz to 1 kHz. 14. The method of claim 13, wherein the voltage of the pulsed electromagnetic radiation is in the range of 350 V to 500 V. 14. The method of claim 13, wherein the pulse number of the pulsed electromagnetic radiation is in the range of 1 to 100. The method of claim 13, wherein the energy of the pulsed electromagnetic radiation is in the range of ^{0.1 J/cm 2} to 100 J/cm ^2. 14. The method of claim 13, wherein the irradiation time of the pulsed electromagnetic radiation is within a range of 1 second to 30 minutes. The method of claim 1, wherein the green structure is in the form of a film or sheet.

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