KR101907888B1 - Metal product having nanopores and method for manufacturing the same - Google Patents

Abstract

A method for producing a metal article having a double ceramic mold and a nano pore is disclosed.
The three-dimensional ceramic molds included in the dual ceramic molds can be precisely manufactured by using 3D printing, have high strength characteristics, and the metal casting molds are refractory materials having high strength. .
In the present invention, a metal product is formed from a super-heat-resistant alloy material, nanopores of nanometer size are formed in the sacrificial particle site by selectively extracting the nanoparticle-formed sacrificial particles by introducing the metal product into the acid solution.
Thus, a porous metal article having a large surface area can be produced by the sacrificial particles.
A method of manufacturing a metal product using a dual ceramic mold comprising a three-dimensional ceramic mold and a metal casting mold according to the present invention, the method comprising: (a) preparing a three-dimensional ceramic mold from ceramic powder using 3D printing; (b) placing the three-dimensional ceramic mold in an inner space of the metal casting mold, and then injecting and cooling molten metal including nano-sized sacrificial particles into the inner space of the metal casting mold; And (c) separating the cooled metal from the mold for metal casting, introducing the metal containing the three-dimensional ceramic mold into an alkaline solution to solvent-extract the three-dimensional ceramic mold, And selectively extracting the nano-sized sacrificial particles from the solution by injecting a metal containing the nano-sized sacrificial particles into an acid solution, wherein nanopores are formed in the selectively extracted nano-sized sacrificial particles .

Description

Technical Field [0001] The present invention relates to a metal product having nano pores,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for manufacturing a metal product, and more particularly, to a method for manufacturing a metal product having a dual ceramic mold and nano pores.

The mold is used to produce products such as synthetic resin and metal in a desired shape. The metal is injected through the injection hole of the mold to manufacture the product according to the shape of the mold. Such a mold includes, for example, a plastic injection mold, a press mold, and the like, and a metallic material is machined to produce a mold.

However, when manufacturing a metal mold by machining a metal material, it is time-consuming and has a limitation in manufacturing a highly precise mold product requiring complicated shape or dimensional accuracy. In addition, when the mold is manufactured so that the dimensions do not match, there is a problem that workability and productivity are deteriorated because it is manufactured by machining from the beginning. On the other hand, there is a method of manufacturing a mold in which holes and patterns are formed by a method of compressing using a concavo-convex mold, but since the holes are monotonous and natural, and artificial images are strong, there is a limit to show a natural and irregular effect .

As a background art related to the present invention, Korean Patent Laid-Open Publication No. 10-2013-0025634 (published on Mar. 13, 2013) discloses a method of manufacturing a porous metal material using electrolytic casting.

It is an object of the present invention to provide a dual ceramic mold using 3D printing.

Another object of the present invention is to provide a method for producing a porous metal article having nanopores by using the above-mentioned dual ceramic mold.

In order to accomplish the above object, the present invention provides a method of manufacturing a metal product using a double-ceramic mold including a three-dimensional ceramic mold and a metal casting mold, comprising the steps of: (a) Producing a ceramic mold; (b) placing the three-dimensional ceramic mold in an inner space of the metal casting mold, and then injecting and cooling molten metal including nano-sized sacrificial particles into the inner space of the metal casting mold; And (c) separating the cooled metal from the mold for metal casting, introducing the metal containing the three-dimensional ceramic mold into an alkaline solution to solvent-extract the three-dimensional ceramic mold, And selectively extracting the nano-sized sacrificial particles from the solution by injecting a metal containing the nano-sized sacrificial particles into an acid solution, wherein nanopores are formed in the selectively extracted nano-sized sacrificial particles .

The average particle diameter of the sacrificial particles may be 1 to 500 nm.

The material of the ceramic powder is silica (SiO _2), alumina (Al ₂ O _3), chromium oxide (Cr ₂ O _3), magnesium oxide (MgO), calcium oxide (CaO), iron oxide (FeO), tin oxide (SnO ₂ ), titanium dioxide (TiO ₂ ), zirconia (ZrO ₂ ), hafnium oxide (HfO ₂ ), tantalum oxide (Ta ₂ O ₅ ), ruthenium oxide (RuO ₂ ) and rare earth oxides .

The metal may comprise 50 to 90% by weight of the molten metal and 10 to 50% by weight of the sacrificial particles, based on 100% by weight of the molten metal and the sacrificial particles.

The acid solution includes distilled water and an acid material including nitric acid, hydrochloric acid, sulfuric acid, hydrofluoric acid, phosphoric acid, or acetic acid, and the acid material may be included in an amount of 30 to 80 wt% based on 100 wt% of the distilled water and the acid material .

The three-dimensional ceramic mold may be surface-treated with an inorganic ceramic composition.

After the step (c), (d) the acid solution is injected into the metal to completely extract the nano-sized sacrificial particles existing outside the metal by solvent extraction.

(D), and (e) washing and drying the resultant of step (d).

According to another aspect of the present invention, there is provided a metal product including nano-pores according to the present invention, wherein the metal product includes hollow voids having a hollow shape, a sacrificial particle is partially contained in the metal product, The density of the nano pores contained in the outside of the metal product is larger than the density of the nano pores contained in the inside of the metal product.

According to another aspect of the present invention, A dual-ceramic mold for manufacturing a metal product, wherein the double-ceramic mold includes a metal casting mold and a three-dimensional ceramic mold disposed in the mold cavity, and the three-dimensional ceramic mold includes a ceramic powder .

The material of the ceramic powder is silica (SiO _2), alumina (Al ₂ O _3), chromium oxide (Cr ₂ O _3), magnesium oxide (MgO), calcium oxide (CaO), iron oxide (FeO), tin oxide (SnO ₂ ), titanium dioxide (TiO ₂ ), zirconia (ZrO ₂ ), hafnium oxide (HfO ₂ ), tantalum oxide (Ta ₂ O ₅ ), ruthenium oxide (RuO ₂ ) and rare earth oxides .

The three-dimensional ceramic mold may be surface-treated with an inorganic ceramic composition.

According to the present invention, a three-dimensional ceramic mold included in a dual ceramic mold is manufactured using 3D printing, so that it can be precisely manufactured and can have high strength characteristics. In addition, nanopores of nanometer size are formed in the sacrificial particle sites by selectively extracting the nanoparticles of the sacrificial particles by introducing the metal product into the acid solution. As the nano pores are formed, porous metal products having a wide surface area can be produced, which can be applied to heat radiation products, gas sensing, and the like.

1 is a flowchart showing a method of manufacturing a metal product according to the present invention.
2 is a schematic view illustrating a process of manufacturing a metal product using the dual ceramic mold according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method of manufacturing a dual ceramic mold and a nano-pored metal product according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart showing a method of manufacturing a metal product according to the present invention. 2 is a schematic view illustrating a process of manufacturing a metal product using the dual ceramic mold according to the present invention.

Referring to FIGS. 1 and 2, a method of manufacturing a metal product according to the present invention includes the steps of fabricating a three-dimensional ceramic mold from a ceramic powder using 3D printing (S110), forming a three-dimensional ceramic mold A step S120 of injecting molten metal and a step S130 of extracting a solvent.

A step (S110) of fabricating a three-dimensional ceramic mold from ceramic powder using 3D printing,

The three-dimensional ceramic mold (10) of the present invention is manufactured through the following process.

The 3D ceramic mold 10 is prepared from the ceramic powder using 3D printing, and the ceramic powder is dissolved in an alkali solution and extracted as a solvent when the solution is introduced into an alkali solution in a solvent extraction step described later. A three-dimensional ceramic mold can be manufactured by performing a pretreatment process such as surface treatment to improve process efficiency. At this time, the coating layer formed by the surface treatment in the three-dimensional ceramic mold is also dissolved in the alkali solution.

The three-dimensional ceramic mold is then separated from the cooled metal through a solvent extraction process. At this time, in order to easily separate the three-dimensional ceramic mold from the metal, it is preferable to surface-treat the surface of the three-dimensional ceramic mold with the inorganic ceramic composition. The surface treatment means forming a coating layer having a thickness of about 0.1 to 10 mu m, and the inorganic ceramic composition is required to have stability not to be removed during the process of manufacturing the metal product through the cooling process after contact with the hot metal melt.

Such an inorganic ceramic composition may be a composition having a high reactivity with an alkaline solution and a low reactivity with a molten metal to be injected. The surface treatment may be performed by spraying and applying the inorganic ceramic composition onto the surface of the three-dimensional ceramic mold, or may be performed by 3D printing. For example, the inorganic ceramic composition may include a ceramic material selected from the group consisting of TEOS, tetraethylorthosilicate, zinc acetate, boron carbide (B ₄ C), tungsten sulfide (WS ₂ ), zinc oxide (ZnO) Inorganic fluorides such as titanium oxide (TiO ₂ , Titanium oxide), hexagonal boron nitride (HBN), CaF ₂ and MgF ₂ , silica (Silica), glycidol, ethanol can do.

The material of the ceramic powder is silica (SiO _2), alumina (Al ₂ O _3), chromium oxide (Cr ₂ O _3), magnesium oxide (MgO), calcium oxide (CaO), iron oxide (FeO), tin oxide (SnO ₂ ), titanium dioxide (TiO ₂ ), zirconia (ZrO ₂ ), hafnium oxide (HfO ₂ ), tantalum oxide (Ta ₂ O ₅ ), ruthenium oxide (RuO ₂ ) and rare earth oxides . Examples of rare earth oxides include yttrium oxide (Y ₂ O ₃ ), cerium oxide (Ce ₂ O ₃ ), and the like.

The 3D printing is a technology for continuously forming a three-dimensional product by layer-by-layer deposition, and can produce a 3D ceramic mold 10 having a complicated shape and a fine size. 3D printing is classified into liquid, powder, and solid depending on the raw material, and there is a method of solidifying and laminating based on sources such as laser, heat, and light.

The 3D printing process can be performed as follows. First, the ceramic powder is supplied through a supply reel, and the ceramic powder to be supplied is melted and discharged to the work table. The ejection is carried out in a nozzle mounted in a three-dimensional transport mechanism which is positioned in three directions X, Y and Z. The three-dimensional transport mechanism moves freely according to the path calculated from the three-dimensional program, and the process parameters such as the printing speed and the position of the supply reel can be controlled in real time by the three-dimensional program. By forming the two-dimensional planar shape by discharging, the molten ceramic powder is stacked on the working table one by one, and a three-dimensional product can be manufactured.

Conventionally, a metal mold is manufactured for manufacturing a metal material by a casting method, but this has a disadvantage in that the production yield and productivity are lowered and the precision is not excellent. In the present invention, the 3D ceramic mold 10 is manufactured by using 3D printing, thereby improving precision, productivity, and manufacturing yield.

A step (S120) of injecting the molten metal after disposing the three-dimensional ceramic mold in the inner space of the metal casting mold,

Next, after placing the three-dimensional ceramic mold 10 in the inner space of the metal casting mold frame 20, molten metal is injected into the inner space of the mold frame 20 and cooled.

The metal casting mold frame 20 is formed of a normal refractory material having high strength and may be formed of a material mainly composed of alumina, silica, or the like, for example. The molten metal is injected into the inner space of the metal casting mold 20. To prevent the mold 20 from being crushed during injection, the melting point of the mold 20 is preferably at least 120 ° C. higher than the melting point of the molten metal . The melting point of the three-dimensional ceramic mold 10 is preferably at least 120 ° C higher than the melting point of the molten metal in order to prevent the three-dimensional ceramic mold 10 from being collapsed when the melted metal is injected.

The material of the molten metal is preferably a super-heat-resistant alloy such as a nickel (Ni) alloy, a titanium (Ti) alloy or an iron (Fe) alloy and has a low reactivity with an alkali solution and an acid solution. (Ag), platinum (Pt), palladium (Pd), molybdenum (Mo), and the like may be used in addition to the above- (Mg), zinc (Zn), lead (Pb), tin (Sn), beryllium (Be), zirconium (Zr), tungsten (W), yttrium (Y), hafnium (Hf), tantalum , Rhenium (Re), ruthenium (Ru), rhodium (Rh) and lanthanum rare metal (rare matal), or an alloy of one or more metals. The lanthanum rare metals include lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), and one or more metals or alloys thereof may be used.

In addition, the molten metal may be provided with a porous metal product 30 having nano pores, which is soluble in an acid solution and contains sacrifice particles or fugitive particles. The material of the sacrificial particles may be a metal having a high reactivity with an acid solution and a low reactivity with an alkali solution and specifically a metal such as Fe, Mg, Al, Cu, Based metal or an alloy thereof. The sacrificial particles are low-melting-point metal particles having a melting point lower than the melting point of the three-dimensional ceramic mold 10 and the metal casting mold 20.

The average particle diameter of the sacrificial particles is preferably 1 to 500 nm, more preferably 10 to 300 nm. When the average particle diameter is less than 1 nm, formation of pores in the solvent extraction process is insufficient, and it may be difficult to produce a metal product having a high surface area. On the contrary, when the thickness exceeds 500 nm, the pores may aggregate to each other, and it may be difficult to form nano-sized pores having a size of nm.

The molten metal is cooled and separated from the metal casting mold 20, and the separated metal is mixed with 50 to 90% by weight of the molten metal and 10 to 50% by weight of the molten metal with respect to 100% by weight of the molten metal and the sacrificial particles . If the sacrificial particles are contained in an amount of less than 10% by weight, porosity may be insufficient to form in the metal product, and it may be difficult to produce the porous metal product. On the other hand, when the sacrificial particles are contained in an amount exceeding 50% by weight, physical properties such as strength of the metal product may be deteriorated.

The molten metal may be injected up to the height of the mold 20 for metal casting, and the molten metal may be mixed with a binder such as polyvinyl alcohol, polymethacrylic acid and the like and a solvent such as ethanol and toluene But is not limited thereto.

The cooling can be quenched to room temperature with air cooling, oil or water cooling.

The solvent extraction step (S130)

Next, after the cooled metal is separated from the mold casting mold 20, the metal containing the three-dimensional ceramic mold is injected into an alkaline solution to solvent-extract the three-dimensional ceramic mold. Next, a metal containing a part of the three-dimensional ceramic mold is put into an acid solution to selectively extract the nano-sized sacrificial particles by solvent extraction.

The cooled metal is separated by removing the metal casting mold frame 20. The separated metal is put into an acid solution to selectively extract the nanoparticles of the sacrificial particles to produce a porous metal product 30 having nanopores. That is, the three-dimensional ceramic mold is firstly subjected to solvent extraction by an alkali solution to form hollows having the same shape. Next, the metal is solvent-extracted with an acid solution to produce a metal product having pores in the sacrificial particle site.

Since the metal may have a part of the three-dimensional ceramic mold during the solvent extraction by the alkali solution, the alkali solution may be introduced into the three-dimensional ceramic mold to completely remove the solvent from the ceramic material. The coating layer formed by the surface treatment in the three-dimensional ceramic mold is dissolved by the alkali solution. Further, the method may further include a step of completely dissolving the sacrificial particles present outside the metal by adding the acid solution into the hollow formed metal.

As a result, it is possible to improve the solvent extraction efficiency of a complicated shape and further improve the nano porosity of the metal product. In addition, a metal product having nano-sized pores can be manufactured.

The alkali solution contains distilled water and an alkaline substance containing sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca (OH) ₂ ) or barium hydroxide (Ba (OH) ₂ ) Any alkali solution (pH 7 <alkaline solution? PH 14) can be selected without limitation. For example, when sodium hydroxide is contained in the alkali solution, the sodium hydroxide may be contained in an amount of 30 to 80% by weight based on 100% by weight of the distilled water and the sodium hydroxide, preferably 50 to 70% %. &Lt; / RTI &gt; If sodium hydroxide is contained in an amount of less than 30% by weight, the solubility of the ceramic material in the alkali solution may be lowered. On the other hand, if it is more than 80% by weight, an excessive cost is required without effect of solvent extraction, and it is not preferable because a high concentration of an alkali solution may contaminate the environment during disposal treatment.

The acid solution (pH 0 < acid solution &lt; pH 7) comprises distilled water and an acid material including nitric acid, hydrochloric acid, sulfuric acid, hydrofluoric acid, phosphoric acid or acetic acid, To 80% by weight. Preferably, the acid material may be contained in an amount of 50 to 70% by weight. When the acid substance is contained in an amount of less than 30% by weight, the concentration of the acid solution becomes thinner, so that the solubility in the sacrificial particles is lowered, and the selective extraction effect of the sacrificial particles may be insufficient. On the other hand, if it exceeds 80% by weight, an excessive cost is required without effect of solvent extraction, and it is not preferable because a high concentration of an acid solution may contaminate the environment during disposal treatment.

Thus, it is preferable that the alkaline substance and the acid substance are used in a diluted state in distilled water for efficient solvent extraction. In the present invention, a three-dimensional ceramic mold is solvent-extracted with an alkali solution, and the metal product is subjected to solvent extraction with an acid solution to produce a hollow and pored metal product.

Meanwhile, the three-dimensional ceramic mold may contain nanoparticle-formed sacrificial particles. At this time, the acid solution can be used to simultaneously extract the three-dimensional ceramic mold and the sacrificial particles contained in the metal product. In addition, when the three-dimensional ceramic mold and the metal product include the sacrificial particles having different materials, the sacrificial particles of the three-dimensional ceramic mold and the metal product can be respectively subjected to solvent extraction.

Thereafter, the porous metal product 30 may be washed with distilled water, ethanol or the like approximately 2 to 5 times and then dried.

As described above, in the present invention, a three-dimensional ceramic mold can be precisely manufactured using 3D printing, and a metal product including nanopores can be manufactured by a selective solvent extraction process for sacrificial particles contained in a metal product. The manufactured metal product includes hollow voids having a three-dimensional shape, and a part of the sacrificial particles is contained in the metal product. The nanopores may be formed by selective solvent extraction of the sacrificial particles on the outside of the metal product, but the sacrificial particles are not completely extracted into the metal product, so that some of the sacrificial particles remain. Therefore, the density of the nano pores contained in the outside of the metal product is larger than the density of the nano pores contained in the metal product.

For example, the density of nano pores included in the outside may be about 1 × ^{10 8} to ⁹ × ^{10 9} / cm ² , but the present invention is not limited thereto.

The dual ceramic mold used for manufacturing the metal product includes a metal casting mold and a three-dimensional ceramic mold 10 disposed in the mold interior space. The three-dimensional ceramic mold 10 includes a ceramic powder and can be surface-treated with an inorganic ceramic composition, as described above in a method for producing a metal product.

In the present invention, a 3D ceramic mold having high strength and high hardness can be manufactured by using 3D printing. Further, the porous metal product having a high surface area can be produced by selectively removing the sacrificial particles contained in the metal product by solvent extraction to form nano pores in the sacrificial particle site.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is to be understood that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

10: 3D ceramic mold
20: Frame for metal casting
30: Porous metal products

Claims (12)

A method of manufacturing a metal product using a dual ceramic mold including a three-dimensional ceramic mold and a metal casting mold,
(a) fabricating a three-dimensional ceramic mold from ceramic powder using 3D printing;
(b) placing the three-dimensional ceramic mold in an inner space of the metal casting mold, and then injecting and cooling molten metal including nano-sized sacrificial particles into the inner space of the metal casting mold; And
(c) separating the cooled metal from the mold for metal casting, introducing the metal containing the three-dimensional ceramic mold into an alkaline solution to solvent-extract the three-dimensional ceramic mold, Selectively extracting the nano-sized sacrificial particles by solvent extraction by introducing a solvent-extracted metal into an acid solution,
Wherein nanopores are formed in a portion where the nano-sized sacrificial particles are selectively extracted.
The method according to claim 1,
Wherein the sacrificial particles have an average particle diameter of 1 to 500 nm.
The method according to claim 1,
The material of the ceramic powder is silica (SiO _2), alumina (Al ₂ O _3), chromium oxide (Cr ₂ O _3), magnesium oxide (MgO), calcium oxide (CaO), iron oxide (FeO), tin oxide (SnO ₂ ), at least one of titanium dioxide (TiO ₂ ), zirconia (ZrO ₂ ), hafnium oxide (HfO ₂ ), tantalum oxide (Ta ₂ O ₅ ), ruthenium oxide (RuO ₂ ) and rare earth oxides Of the metal product.
The method according to claim 1,
Wherein the metal comprises 50 to 90% by weight of the molten metal and 10 to 50% by weight of the sacrificial particles, based on 100% by weight of the molten metal and the sacrificial particles.
The method according to claim 1,
Wherein the acid solution comprises distilled water and an acid material including nitric acid, hydrochloric acid, sulfuric acid, hydrofluoric acid, phosphoric acid, or acetic acid, wherein the acid material is contained in an amount of 30 to 80 wt% based on 100 wt% of the distilled water and the acid material &Lt; / RTI &gt;
The method according to claim 1,
Wherein the three-dimensional ceramic mold is surface-treated with an inorganic ceramic composition.
The method according to claim 1,
After the step (c)
(d) adding the acid solution into the metal to completely extract the nano-sized sacrificial particles existing outside the metal by solvent extraction.
8. The method of claim 7,
After the step (d)
(e) washing and drying the resultant product of step (d).
In a metal product comprising nanopores,
Wherein the metal product comprises hollow hollow bodies of three-dimensional shape,
Wherein a part of the sacrificial particles is contained in the metal product,
Wherein the density of the nano pores contained in the outside of the metal product is greater than the density of the nano pores contained in the metal product.


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