KR101116192B1 - Method for manufacturing high strength alloy open cell of hollow sphere - Google Patents

Abstract

The present invention relates to a high-strength metal alloy hollow sphere of metal oxides of copper and nickel, and more specifically iii) 50 to 95% by weight of copper oxide powder and 5 to 50% by weight of nickel oxide powder to obtain an oxidation mixture. step; Ii) mixing 50 to 80% by weight of the oxidation mixture with 20 to 50% by weight of a solvent to prepare a slurry; Iii) adding up to 10% by weight of PA (polyacrylamide) based on the total weight of the slurry and mixing; Iii) coating the slurry of step iv) on polymer balls and drying to evaporate the solvent to obtain a copper-nickel oxide; And iii) heating the copper-nickel oxide under a hydrogen atmosphere to reduce the copper-nickel oxide. As a result, high-strength alloy hollow spheres having improved mechanical properties can be manufactured. In addition, nickel has the advantage that alloying is advantageous as copper and an electrolytic solid solution without limiting its content, it is excellent in high temperature properties and corrosion resistance.

Copper, Nickel, High Strength Alloy Hollow Hole

Description

Method for manufacturing high strength alloy open cell of hollow sphere

The present invention relates to a high-strength metal alloy hollow sphere using a metal oxide of copper and nickel or an alloy oxide in which metal elements of copper and nickel are alloyed.

Hollow spheres produced using pure copper oxide are pore generated by a reduction reaction during sintering, densified by shrinkage (Fig. 2). However, pure copper has excellent electrical properties, but is well deformed and has limitations for use as a structural material. Recrystallization temperature of 150 ° C. or lower has limitations on the use temperature [Reference: Ja-Myeong Koo and Seung- Boo Jung: Materials Science Forum, vol. 510-511 (2006), p. 730-733].

In general, metal oxides are reduced in a hydrogen atmosphere and a constant temperature at a high temperature by the following chemical reaction. When two or more metal oxides are present, the metal oxides are reduced from a relatively reducing metal [Reference: Lee Dong-bok, Materials Thermodynamics, Boseong Hwasa, p. 285-291].

MO _x + xH _2- > xM xH ₂ O

The reduced metal is present in a very active state instantaneously, easily reacts with other elements around it, and a brass hollow sphere alloyed with copper and zinc is produced by the following procedure.

(1) reduction and activation of copper oxides

(2) reduction and activation of zinc oxide

(3) simultaneously dissolved as a substitution type within the copper base of activated zinc (metal ion activation promotes bonding reaction).

(4) Precipitation or solid solution state depending on cooling conditions during cooling

This principle is applicable to the production of other alloy hollow spheres, and because of the low loss of the combined metal oxides, the excess additive metal can be effectively dissolved and reacted in the metal matrix.

The alloying of copper with zinc increases the mechanical properties, but due to the low melting point and high vapor pressure of zinc, a significant amount of zinc is lost at the address of the alloy. In addition, under a hydrogen atmosphere, zinc oxide has a lower reducibility than copper oxide and thus is reduced relatively late.

In addition, in the brass hollow spheres made of copper oxide and zinc, zinc is not dissolved in the copper base during sintering, and evaporated to produce hollow pores with many pores (FIG. 3). This can increase the cross-sectional area of the hollow spheres and have usefulness as a filter or electrode material. However, due to the formation of a large number of voids, the compressive strength is very low, and the combined elements are mostly evaporated, making it difficult to alloy the desired composition [ References: Ja-Myeong Koo, Hideki Araki and Seung-Boo Jung: Effect of Zn addition on mechanical properties of brass hollow spheres, Materials Science and Engineering A, In-Press.

As a result, in the present invention, an alloy hollow sphere having high strength characteristics is to be manufactured, and the density of the hollow sphere can be variously adjusted according to the sintering temperature, and an alloy hollow sphere having a free composition ratio is produced according to the ratio of the combined metal oxides. I would like to.

It is an object of the present invention to provide a method for producing a high strength metal alloy hollow sphere using metal oxides of copper and nickel in accordance with the present invention.

The present invention comprises the steps of: i) mixing 50 to 95% by weight of copper oxide powder with 5 to 50% by weight of nickel oxide powder to obtain an oxidation mixture; Ii) mixing 50 to 80% by weight of the oxidation mixture with 20 to 50% by weight of a solvent to prepare a slurry; Iii) adding up to 10% by weight of PA (polyacrylamide) based on the total weight of the slurry and mixing; Iii) coating the slurry of step iv) on polymer balls and drying to evaporate the solvent to obtain a copper-nickel oxide; And iii) heating the copper-nickel oxide under a hydrogen atmosphere to reduce the copper-nickel oxide.

Preferably, the high-strength metal alloy hollow sphere according to the present invention can be prepared by a slurry of a metal or an alloy oxide to lower the density can be uniformly dispersed in a solvent.

Preferably, in order to prepare a metal oxide or alloy oxide, the waste bulk material, scrap or dust (pulverized metal powder) may be finely pulverized into powder or ribbon, and then oxidized. It is possible to use an oxide powder or a ribbon that is finely crushed once more, or a metal or alloy oxide in the form of a powder prepared in advance. At this time, the diameter of the powder or ribbon is a particle size of 1/50 or less of the diameter of the hollow sphere to be finally produced, but is not limited thereto.

Preferably, the additive metal oxides compared to the parent alloy may be combined in a range of 0.001 to 50%, and after cooling the hollow spheres to cool the precipitates to precipitate the additive metals in the master alloy, the mixture is cooled at room temperature using water or liquid nitrogen. Aging may be performed within 3 hours at a temperature in the range of 50 ° C. to 95% of the melting point, thereby finely depositing the additive metal in the mother alloy grain or at the grain boundary, thereby improving strength.

Preferably, water, alcohol, acetone, tetradecane or thiol system may be used as a solvent, and polyvinyl alcohol (PVA: Poly Vinyl Acetate) or PMMA (Poly Methyl Meth Acrylate) or PA (Poly Acrilamide) as a binder. ) Can be used. When using acetone as a solvent, to prevent dissolving in the acetone of the polymer ball, use a paraffin ball that is coated with paraffin on the surface of the polymer ball or does not leave a residue that completely sublimes upon heating without being dissolved in the solvent instead of the polymer ball. Can be.

Preferably, the binder may be combined at up to 10% of the total weight of the slurry, most preferably at most 5% by weight of the total weight of the slurry.

Preferably, the metal oxide powder of copper and nickel or the alloy oxide powder and the solvent consisting of copper and nickel metal elements may have a weight ratio of 7: 3.

Preferably, step iii) may be heated at 700 to 930 ° C. for 1 hour under a hydrogen atmosphere.

Preferably, the polymer ball may be a substance which is easily dissolved in acetone, benzene, or toluene, such as polystyrene, or easily decomposed when heated, and may be deposited or injected into acetone, toluene, or benzene, if necessary, into the polymer. The ball can be infiltrated. In addition, the slurry may be sprayed onto the polymer balls or coated with a desired thickness on the polymer ball surface using a dipping method.

Preferably, the high-strength alloy hollow sphere according to the present invention may have a sintering temperature of 400 ° C. or more, and a sintering time of 1 minute or more.

According to the present invention by the above-mentioned means for solving the problem, nickel has the advantage of alloying without limiting the content of copper and the electrolytic solid solution, and in the case of nickel-containing cupronickel compared to zinc-containing brass, high temperature characteristics It has the advantage of high corrosion resistance and mechanical strength.

In addition, impurity atoms evaporate during the oxidation and sintering process, making it possible to manufacture high-purity foam metals, and by controlling the sintering temperature and time, the size of the hollow spheres (diameter: 1 mm to 300 mm) and the metal shell ) The thickness (diameter: 0.01 mm ~ 200 mm) and the size of the pores in the shell (diameter: 0.01 mm ~ 200 mm) can be freely controlled, and various reinforcement by adjusting the cooling rate in the cooling process after sintering or after heat treatment after cooling Or increase the ductility and toughness.

Hereinafter, the present invention will be described in detail through the following examples.

Example

Example 1 Preparation of Copper-Zinc Hollow Spheres

Oil and contaminants on copper and zinc pure metal or copper-zinc alloy scraps were heated and oxidized to remove oxides of low specific gravity. Alternatively, copper oxide and zinc oxide or copper-zinc alloy oxide can be used directly without an oxidation process.

PA was prepared as a binder, water was prepared, and copper oxide powder, zinc oxide powder, PA, and water were sufficiently stirred to prepare a slurry. At this time, the weight ratio of the copper and zinc oxide powder and the solvent was 7: 3, and the PA was mixed at 5% by weight based on the total weight of the slurry. After coating on the polymer ball by quenching the slurry prepared above, the solvent was evaporated by drying in 25 ℃, 50% RH atmosphere. The oxide was reduced to a copper-zinc alloy hollow sphere by heating for 1 hour at 800 ° C. and 930 ° C. under hydrogen atmosphere. At this time, the temperature increase rate was 15 degreeC / s, and the cooling rate was -15 degreeC / s.

Thus, the polymer balls inside disappeared during sintering, completing the copper-zinc alloy hollow sphere according to the present invention.

4 and 5 are cross-sectional photographs of brass (copper-zinc) hollow spheres prepared by sintering 30 wt% and 20 wt% zinc oxide at 800 ° C. and 930 ° C. for 1 hour according to Example 1 of the present invention. In the case of FIG. 4, pores were more fine and uniform hollow spheres were obtained, and in FIG. 5, a perfect sintered body with almost no pores was obtained.

6 is a result of measuring the compressive strength of the prepared hollow sphere according to the sintering temperature and the amount of zinc oxide. The mechanical properties increased with increasing sintering temperature, and showed the maximum mechanical properties when the ZnO content was 20% by weight.

Example 2: Preparation of Copper-Nickel Hollow Spheres

Oil and contaminants on copper and nickel pure metal or copper-nickel alloy scraps were heated and oxidized to remove oxides. However, copper oxide and nickel oxide or copper-nickel alloy oxide can be used directly without oxidation process.

PA was prepared as a binder, and water was used as a solvent. 70 to 95 wt% of copper oxide powder and 5 to 30 wt% of nickel oxide powder were mixed. PA and water were added to the mixture and stirred sufficiently to prepare a slurry. At this time, the weight ratio of the mixture and the solvent was 7: 3, PA was mixed at 5% by weight based on the total weight of the slurry. After coating on the polymer ball of polystyrene by quenching the slurry prepared above, the solvent was evaporated by drying in 25 ℃, 50% RH atmosphere. Subsequently, the oxide was reduced to a copper-nickel alloy hollow sphere by heating at a temperature of 700 ° C. and 930 ° C. under a hydrogen atmosphere for 1 hour. At this time, the temperature increase rate was 15 ° C / s, the cooling rate was -15 ° C / s. After sintering the hollow spheres, the mixture is cooled at room temperature using water or liquid nitrogen, and then aged at 50 ° C. to 1350 ° C. for 3 hours to precipitate the additive metal in the grains of the alloy tool or at the grain interface. The strength was improved by doing so.

Therefore, the polymer ball inside was extinguished during sintering, and the high quality alloy hollow sphere according to the present invention was obtained by classifying good products by inspecting the desired shape, size and amount of added elements.

7 and 8 are cross-sectional photographs of nickel hollow spheres prepared by sintering 5% by weight and 30% by weight of nickel oxide in 930 ° C and 700 ° C for 1 hour according to Example 2 of the present invention. As the sintering temperature decreases and the amount of nickel oxide increases, the amount of pores in the material increases.

9 is a result of measuring the hardness of the sintered compact with a Vickers hardness tester according to the sintering temperature and the amount of nickel oxide. The mechanical properties increased with increasing sintering temperature and nickel content.

Example 3: Quantitative Analysis According to Sintering Temperature

11 shows the results of measuring the amount of additional elements present in the hollow spheres after the hollow spheres were prepared by using a slurry obtained by mixing 30% by weight of zinc, zinc oxide and nickel oxide with copper oxide.

Since zinc has a very low melting point and vapor pressure compared to copper, the efficiency is low compared to the amount added, but nickel has a high yield because it has properties similar to copper. Therefore, in order to match the alloy ratio of a certain content, it is possible to minimize the amount of nickel to be added.

Example 4 Quantitative Analysis According to Sintering Temperature

12 is a result of measuring the strength of the surface of the hollow sphere according to the sintering temperature after adding 20% by weight of zinc, zinc oxide and nickel oxide in the copper oxide.

Nickel oxide was observed to increase the strength of about 80% compared to the case of adding zinc in the copper material, and about 50% strength increase effect was observed compared to the case of adding zinc oxide. When only zinc is added, it can be seen that strength decrease due to pores generated by evaporation of the zinc element during sintering.

Example 5 Configuration of Sintering Furnace

13 is a shape of a sintering furnace, continuous sintering is possible by the transfer device, it is divided into three zones. The heating zone and the cooling zone are inert gas atmospheres such as nitrogen and argon, and the sintering zone is a reducing atmosphere filled with hydrogen gas. At this time, the temperature increase and the cooling rate can be adjusted according to the temperature of the nitrogen gas. The reason why the barriers are formed in the second zone is to control the temperature differently in each zone to achieve effective sintering and reduction. In addition, the heating device is to create an optimal misleading profile for producing a high quality alloy hollow sphere by varying the temperature in each zone.

Nitrogen and hydrogen gas can be used as a proportion of the mixed gas, if necessary, by circulating at a constant flow rate to maintain a high quality atmosphere at all times, it is possible to continuously produce through a conveyor can increase the production yield. Zones 1 and 3 are equipped with a simple flame igniter or oxidizer at regular intervals to prevent oxygen from entering the zone 2 from outside, and the gases from zone 2 are constantly burned to react and explode with hot hydrogen and oxygen outside. To prevent them.

The present invention relates to high-strength metal alloy hollow spheres of metal oxides of copper and nickel, and because they have higher strength than other metal structures, they are not only used for high temperature heat exchangers and heat sinks, but also for bumpers or other structural materials. It is possible. As a result, various applications such as automobile shock absorbers, electromagnetic shielding devices, filters, heat exchangers, automobile and aircraft structural materials, and building materials are possible. The company is expected to replace the company with a new market, based on its price competitiveness and strength. In addition, copper and nickel alloy hollow spheres are excellent in high temperature and heat resistance characteristics, it can be applied to power plants, aerospace materials, ships, submarines and chemical plants that require high temperature heat exchangers, heat sinks and bumpers and sound-absorbing materials.

1 illustrates a manufacturing sequence of the present invention.

Figure 2 shows a cross-sectional photograph of a copper hollow sphere of the prior art.

Figure 3 shows a cross-sectional picture of the brass hollow sphere of the prior art.

Figure 4 shows a photograph of a brass (copper + zinc) hollow sphere sintered at 800 ℃ in accordance with the present invention.

Figure 5 shows a photograph of a brass (copper + zinc) hollow sphere sintered at 930 ℃ in accordance with the present invention.

Figure 6 shows the compressive strength results of the brass hollow sphere produced through the present invention.

Figure 7 shows a photograph of a cuprous (copper + nickel) hollow sphere sintered at 930 ℃ according to the invention.

Figure 8 shows a photograph of a cuprous (copper + nickel) hollow sphere sintered at 700 ℃ according to the invention.

Figure 9 shows the results of measuring the surface hardness of the copper-nickel hollow sphere according to the present invention.

Figure 10 shows a schematic diagram of the hollow sphere according to the present invention.

11 shows the results of quantitative analysis of zinc or nickel in the hollow spheres according to the sintering temperature when copper oxide and zinc, zinc oxide and nickel oxide are added.

Figure 12 shows the results of measuring the strength of the hollow sphere surface according to the sintering temperature when the copper oxide and zinc, zinc oxide and nickel oxide is added.

Figure 13 shows a schematic diagram of the sintering apparatus of the present invention.

Claims (9)

In the production of high strength alloy hollow spheres, V) mixing 50 to 95% by weight of copper oxide powder with 5 to 50% by weight of nickel oxide powder to obtain an oxidation mixture; Ii) mixing 50 to 80% by weight of the oxidation mixture with 20 to 50% by weight of a solvent to prepare a slurry; Iii) mixing by adding 1 to 10% by weight of PA (polyacrylamide) based on the total weight of the slurry; Iii) coating the slurry of step ii) on polymer balls and drying to evaporate the solvent to obtain a copper-nickel oxide; And Iii) a method for producing a high strength alloy hollow sphere comprising the step of reducing the copper-nickel oxide by heating in a hydrogen atmosphere. The method of claim 1, wherein the solvent in step ii) is water, alcohol, acetone, tetradecane or thiol system. The method of claim 1, wherein in step i), the solvent is evaporated by drying under a temperature of 10 to 25 ° C. and a humidity atmosphere of 50 to 80% RH to evaporate the solvent. The method of manufacturing a high-strength alloy hollow sphere according to claim 1, wherein the heating is performed at 700 to 930 ° C. for 1 hour in step iii). The method according to claim 1, wherein after step v), the mixture is cooled at room temperature using water cooling or liquid nitrogen, and then aged at 50 ° C. to 1350 ° C. for 1 to 3 hours, and then in the grains of the alloy hollow tool. Or depositing a metal added to the grain boundary. delete The method of claim 1, wherein the oxidizing mixture and the solvent in the step ii) is a weight ratio of 7: 3. The method of claim 1, wherein the PA is 1 to 5% by weight based on the total weight of the slurry. delete

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