Ultra-light metal oxide composite and preparation method thereof

Abstract

The present invention provides an ultra-light metal oxide composite and a preparation method thereof.

Description

Superhard metal oxide composite and method for producing the same

[0001] The present invention relates to a superhard metal oxide composite and a method for producing the same.

[0002] Cemented carbide is a composite material composed primarily of tungsten (W) or cobalt (Co), and is bonded to tungsten carbide (WC), which has a high melting point and hardness, by cobalt (Co). It possesses both high hardness and high strength. Cemented carbide is primarily used in various cutting tools, materials for machinery requiring wear and corrosion resistance, molds, and tools for oil mining and rock crushing. Recently, it has also been used in cutting-edge industries such as semiconductor molds, micro-high-precision equipment for substrate processing, and LCD cutters.

[0003] The manufacturing process for tools using tungsten carbide-cobalt based hard metal materials may include a sintering process, and the sintered hard metal tools in the sintering process go through a post-processing process including machining. During the sintering process and the post-processing, a large amount of hard metal sludge is generated. Furthermore, with the development of industry, the use of various cutting tools, machinery materials, molds, tools for oil mining and rock crushing is increasing, and the amount of discarded hard metal is also increasing. This hard metal scrap is divided into soft scrap in powder form and hard scrap in lump form.

[0004] The representative recycling technologies currently in use to recover valuable metal components from such superhard metal scrap can be broadly classified into three types: the Zn method, the electrolysis method, and the chemical method.

[0005] In order to recover valuable metal components from superhard metal scrap with high efficiency and high purity while reducing the use of large amounts of chemicals, a method is required to pre-process or pre-process high-hardness superhard metal scrap to increase the recovery efficiency of valuable metal components and reduce costs.

[0006] [Prior Art Literature]

[0007] [Patent Document]

[0008] Domestic Patent No. 10-2459922

[0009] The problem to be solved by the present invention relates to a method for manufacturing a superhard metal oxide composite by chemically treating and physically processing a superhard metal, so as to enable precision processing of the superhard metal material while recovering valuable metal components from the superhard metal with high efficiency and high purity, and to a superhard metal oxide composite manufactured thereby.

[0010] In order to solve the above problem, the present invention provides a superhard metal oxide composite and a method for manufacturing a superhard metal oxide composite, which includes columnar particles having at least one rounded shape and amorphous particles present on at least a portion of the surface of the columnar particles.

[0011] According to the superhard metal oxide composite and the method for manufacturing the same according to the present invention, precision processing of superhard metal materials is enabled, processing into a desired shape is facilitated, and the recovery efficiency of valuable metal components from the superhard metal oxide composite can be increased and costs can be reduced.

[0012] Figure 1 is a SEM image taken at 2,000 times magnification of a superhard metal oxide composite according to one embodiment of the present invention.

[0013] Fig. 2(a) is a SEM image taken at a magnification of 5,000 times of a superhard metal oxide composite according to one embodiment of the present invention. Fig. 2(b) shows the length of an arbitrary columnar particle of the composite measured in the longitudinal direction.

[0014] Fig. 3(a) is a SEM image taken at a magnification of 10,000 times of a superhard metal oxide composite according to one embodiment of the present invention. Fig. 3(b) is a measurement of the length or width of any irregular particles present on the surface of some of the columnar particles of the composite.

[0015] Fig. 4 is an SEM image of the surface of a superhard metal oxide composite according to one embodiment of the present invention. Fig. 4(a) is an SEM image taken at a magnification of 63 times, Fig. 4(b) is an SEM image taken at a magnification of 150 times, Fig. 4(c) is an SEM image taken at a magnification of 260 times, Fig. 4(d) is an SEM image taken at a magnification of 1200 times, and Fig. 4(e) is an SEM image taken at a magnification of 5000 times.

[0016] FIG. 5 is a graph showing the spectrum of tungsten (W), cobalt (Co), oxygen (O), carbon (C), chromium (Cr), and platinum (Pt), which are components contained in arbitrary columnar particles of a composite according to one embodiment of the present invention, and the content thereof analyzed.

[0017] FIG. 6 is a graph showing the spectrum of tungsten (W), cobalt (Co), oxygen (O), carbon (C), chromium (Cr), and platinum (Pt), which are components contained in arbitrary columnar particles of a composite according to one embodiment of the present invention, and the content thereof analyzed.

[0018] FIG. 7 is a graph showing the spectrum of tungsten (W), cobalt (Co), oxygen (O), carbon (C), chromium (Cr), and platinum (Pt), which are components contained in random amorphous particles of a complex according to one embodiment of the present invention, and the content thereof analyzed.

[0019] FIG. 8 is a graph showing the spectrum of tungsten (W), cobalt (Co), oxygen (O), carbon (C), chromium (Cr), and platinum (Pt), which are components contained in random amorphous particles of a complex according to one embodiment of the present invention, and the content thereof analyzed.

[0020] Hereinafter, various embodiments of the present invention will be described with reference to the accompanying drawings. It should be understood that the present invention is not limited to specific embodiments, but rather encompasses various modifications, equivalents, and / or alternatives of the embodiments of the present invention. In the description of the drawings, similar reference numerals may be used for similar components.

[0021] In this document, the expressions “has”, “may have”, “includes”, or “may include” indicate the presence of a feature (e.g., a number, function, operation, or component such as a part), but do not exclude the presence of additional features.

[0022] In this document, the expressions "A or B," "at least one of A and / or B," or "one or more of A and / or B" can include all possible combinations of the listed items. For example, "A or B," "at least one of A and B," or "at least one of A or B" can all refer to cases where (1) at least one A is included, (2) at least one B is included, or (3) at least one A and at least one B are included.

[0023] The expression "configured to" as used herein can be used interchangeably with, for example, "suitable for", "having the capacity to", "designed to", "adapted to", "made to", or "capable of". The term "configured to" does not necessarily mean "specifically designed to".

[0024] The terms used in this document are used only to describe specific embodiments and may not be intended to limit the scope of other embodiments. The singular expression may include the plural expression unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by those of ordinary skill in the art described in this document. Terms defined in general dictionaries among the terms used in this document may be interpreted as having the same or similar meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined in this document. In some cases, even if a term is defined in this document, it cannot be interpreted to exclude the embodiments of this document.

[0025] The embodiments disclosed in this document are presented for the purpose of explaining and understanding the disclosed technical content and are not intended to limit the scope of the present invention. Therefore, the scope of this document should be interpreted to include all modifications or various other embodiments based on the technical concept of the present invention.

[0026] Hereinafter, preferred embodiments of the present invention will be described in detail. Prior to this, it should be noted that the terms and words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings. Based on the principle that the inventor can appropriately define the concept of a term to best explain his or her invention, they should be interpreted in a way that aligns with the technical spirit of the present invention.

[0027] Accordingly, the configurations of the embodiments described in this specification are only some of the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention, so it should be understood that there may be various equivalents and modified examples that can replace them at the time of filing this application.

[0028] Throughout the specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise stated.

[0029] Hereinafter, the present invention will be described in detail.

[0030]

[0031] A superhard metal oxide composite according to one embodiment of the present invention comprises columnar particles having at least one rounded shape and amorphous particles present on at least a portion of the surface of the columnar particles. Each component is described in detail below.

[0032] The above columnar particles have a shape in which at least one end is rounded, so that the composite can be formed with excellent sinterability. The above columnar particles refer to particles having a shape of a column that supports or supports an object straight from the bottom up, and may include a length direction and a width. The length direction and the width may be the same, but generally mean that the width does not exceed the length in the length direction. In the above columnar particles, the shape in which at least one end is rounded may exhibit an overall round shape, such as a sphere or an oval. As shown in Fig. 1, the columnar particles may have a shape similar to a human finger, and basically have a cylindrical shape, so that the surface area is larger than that of spherical particles. In the case of spherical particles, it is relatively difficult to orient them consistently in the vertical direction, whereas the above columnar particles can easily orient them consistently in the vertical direction.

[0033] The columnar particles may have a length in the longitudinal direction of 0.1 to 100 μm. Preferably, the length in the longitudinal direction of the columnar particles may be in the range of 1 to 50 μm. Most preferably, the length in the longitudinal direction of the columnar particles may be in the range of 2 to 20 μm. Fig. 2(a) is an SEM image taken at a magnification of 5,000 times of a superhard metal oxide composite according to an embodiment of the present disclosure, and Fig. 2(b) is a measurement of the longitudinal direction of the columnar particles of the composite taken in Fig. 2(a). The lengths in the longitudinal direction were measured as 2.008 μm, 2.584 μm, 2.748 μm, 4.275 μm, 5.790 μm, 6.690 μm, 7.674 μm, 7.830 μm, 8.074 μm, 10.220 μm, 11.020 μm, and 14.110 μm.

[0034] The above columnar particles may not have a constant average diameter of the cross-section perpendicular to the longitudinal direction. Since the average diameter of the cross-section perpendicular to the longitudinal direction is not constant, the columnar particles may have various shapes that are deformed from a cylindrical shape. For example, the columnar particles may have various shapes in which the average diameter of the cross-section perpendicular to the longitudinal direction is not constant, such as a crooked columnar shape, a peanut shape, an E. coli shape, a dog's paw shape, a finger shape, etc., in which the average diameter of the cross-section of the cylinder is irregular and deformed (see FIG. 2(a) or FIG. 3(a)).

[0035] The amorphous particles present on at least a portion of the surface of the columnar particles may be formed in various shapes. The presence of the amorphous particles on at least a portion of the surface of the columnar particles may maintain a gap between the columnar particles, which may help facilitate the plasticity of the composite. The amorphous particles do not have a specific shape and may be located on the surface of the columnar particles, in pores, or both, as crumb-like aggregates, where the columnar particles are not arranged.

[0036] The length in the longitudinal direction or width of the amorphous particles may be in the range of 0.1 to 10 μm. Preferably, the length in the longitudinal direction or width of the amorphous particles may be in the range of 0.5 to 5 μm. Most preferably, the length in the longitudinal direction or width of the amorphous particles may be in the range of 0.6 to 2 μm. Fig. 3(a) is an SEM image taken at a magnification of 10,000 times of a hard metal oxide composite according to an embodiment of the present disclosure, and Fig. 3(b) is a result of measuring the length in the longitudinal direction or width of the amorphous particles of the composite taken in Fig. 3(a). The lengths in the longitudinal direction or width were measured as 0.7364 μm, 0.7640 μm, 0.8633 μm, 0.9065 μm, 1.2190 μm, 1.3830 μm, and 1.8350 μm.

[0037] The above columnar particles and the amorphous particles include tungsten (W), cobalt (Co), and oxygen (O), and the weight % of oxygen (O) atoms included in the columnar particles may be lower than the weight % of oxygen (O) atoms included in the amorphous particles. That is, the columnar particles may further include valuable metal components such as tungsten (W) and cobalt (Co) compared to the amorphous particles, and when a solution such as sodium carbonate is treated on a superhard metal oxide complex including such columnar particles, the superhard metal oxide complex can be more easily dissolved, thereby reducing residual metal and increasing the yield of ionic valuable metal.

[0038] The above columnar particles and the above amorphous particles may further include at least one selected from the group consisting of carbon (C), chromium (Cr), and platinum (Pt) in addition to tungsten (W), cobalt (Co), and oxygen (O).

[0039] FIGS. 5 and 6 are spectra of tungsten (W), cobalt (Co), oxygen (O), carbon (C), chromium (Cr), and platinum (Pt), which are components contained in arbitrary columnar particles of a composite according to one embodiment of the present disclosure, and analyzed for their contents. The weight % of oxygen (O) atoms contained in the columnar particles may be 5 to 10 wt % based on 100 wt % of the entire columnar particles. Preferably, the weight % of oxygen (O) atoms contained in the columnar particles may be 6 to 8 wt % based on 100 wt % of the entire columnar particles. When the weight % of oxygen (O) atoms contained in the columnar particles based on 100 wt % of the entire columnar particles is included within the above numerical range, the superhard metal oxide composite can ultimately be easily dissolved in a solution such as sodium carbonate, thereby reducing residual metal and increasing the content of ionic valuable metal.

[0040] FIG. 7 and FIG. 8 are spectra of tungsten (W), cobalt (Co), oxygen (O), carbon (C), chromium (Cr), and platinum (Pt), which are components included in arbitrary amorphous particles of a composite according to one embodiment of the present invention, and analysis of their contents. The weight % of oxygen (O) atoms included in the amorphous particles may be 10 to 50 wt % based on 100 wt % of the amorphous particles. Preferably, the weight % of oxygen (O) atoms included in the amorphous particles may be 20 to 40 wt % based on 100 wt % of the amorphous particles.

[0041] A method for manufacturing a superhard metal oxide composite according to one embodiment of the present invention comprises the steps of immersing a superhard metal in an acidic solution to oxidize at least a portion of the superhard metal, heating the oxidized superhard metal, and obtaining an oxide of the heated superhard metal. Each step of the system is described in detail below.

[0042] The step of immersing the hard metal in the acidic solution to oxidize at least a portion of the hard metal is intended to generate microcracks from the surface of the hard metal to the inside of the structure and to expand the volume of the hard metal. Through this oxidation step, the hard metal can be oxidized to a state including tungsten oxide (WO3), cobalt tungsten oxide (CoWO4), and cobalt oxide (Co2O3).

[0043] In general, hard metal is a type of composite material that combines hard metal carbides with soft metal phases. The metal carbides include Tungsten Carbide (WC), Titanium Carbide (TiC), Tantalum Carbide (TaC), and Nibium Carbide (NbC), and the metal phases include Co, Ni, etc., used alone or in combination of two or more, as tool and mold materials. The hardness of hard metal is generally greater than that of balls such as alumina (Al2O3), zirconia (ZrO2), and silicon carbide (SiC) used in ball milling. Therefore, in order to lower the hardness of hard metal before grinding or powdering the hard metal, an acid solution is treated to generate microcracks on the surface, and oxygen on the surface can penetrate into the hard metal and cause its volume to expand.

[0044] Tungsten (W), the main component of hard metals, can expand by more than three times its volume when oxidized. By treating hard metals containing tungsten as their main component with an acidic solution, microcracks are formed on the surface, and these microcracks propagate within the hard metal structure, simultaneously inducing volume expansion, ultimately increasing the specific surface area and facilitating subsequent chemical reactions by mechanical milling. The oxidation step is characterized in that it is maintained in the air for 20 minutes to 6 hours. If the time is less than the above time range, the hard metal combines with oxygen and oxidizes, simultaneously expanding, preventing the phenomenon of the structure spacer from occurring. On the other hand, if the time exceeds the above time range, the amount of oxygen contained in the hard metal carbide composite increases, which may lower the recovery rate of valuable metals. Preferably, the oxidation step can be maintained in the air for 30 minutes to 3 hours. The amount of air and oxygen injected in the oxidation step can be appropriately adjusted by a person skilled in the art depending on the amount of powder to be charged, and preferably, it can be injected at a flow rate of 1 L / min or more.

[0045] The step of heating the above-mentioned oxidized superhard metal can promote volume expansion of tungsten and cobalt through heat treatment. In the case of the oxidized superhard metal, some microcracks are formed within the tungsten or cobalt of the superhard metal, and heat is transferred to the microcracks through heat treatment, thereby further promoting volume expansion.

[0046] The step of obtaining the oxide of the above-mentioned heated superhard metal can obtain an oxide of the superhard metal having microcracks on the surface and inside and having an expanded volume through oxidation and heat treatment.

[0047] The above acidic solution may include at least one selected from the group consisting of hydrogen peroxide (H2O2), hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), and perchloric acid (HClO4).

[0048] In the step of oxidizing at least a portion of the above-mentioned superhard metal, the acidic solution may include at least one selected from the group consisting of hydrogen peroxide (H2O2), hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), and perchloric acid (HClO4), and preferably, the acidic solution is a mixture of hydrochloric acid (HCl) and nitric acid (HNO3) in a ratio of 3:1. The treatment may be performed in the acidic solution for 1 to 12 hours.

[0049] The pH of the above acidic solution may be 1 to 3. If the pH of the above acidic solution is below the lower limit of the above numerical range, it may be impossible to effectively separate and recover the tungsten and cobalt of the cemented carbide using acid leaching. If the pH of the above acidic solution is above the upper limit of the above numerical range, a separate process may be required to leach the undissolved tungsten and cobalt.

[0050] The step of heating the oxidized superhard metal can be performed at 500 to 1000°C for 1 to 6 hours. The step of heating the oxidized superhard metal can enable a chemical reaction by heating the oxidized and volume-expanded superhard metal at 500 to 1000°C for 1 to 6 hours. Preferably, the chemical reaction can be sufficiently achieved by heating at 750 to 950°C for 3 to 5 hours.

[0051] The step of heating the above-mentioned oxidized superhard metal can utilize a rotary kiln. The rotary kiln is a type of heating furnace, a high-efficiency cylindrical rotary kiln. It is a furnace type that places raw materials in a rotating steel cylinder lined with refractory bricks and heats them using hot air or flame. It is mainly used to process materials at high temperatures to induce chemical reactions or physical changes. Such a rotary kiln can be used alone, or by adding balls of various shapes inside, the impact between the materials and the balls can be utilized to promote chemical reactions or physical changes in the materials.

[0052] The above heating step can further apply energy to the hard metal through a mechanical milling process using a rotary kiln. When the oxidized hard metal is heated using such a rotary kiln, kinetic energy can be supplied to the hard metal in the form of thermal energy through the impact generated between the hard metal and the internal surface of the rotary kiln and the impact between the hard metals. This can activate chemical reactions between the hard metal molecules and promote the oxidation of tungsten and cobalt contained in the hard metal.

[0053] In the step of heating the above-mentioned oxidized superhard metal, the superhard metal can be heated together with ceramic balls having a diameter of 5 to 50 mm when using a rotary kiln. Generally, superhard metal has a high hardness, and thus, when using a ball milling method, it is harder than balls such as alumina, zirconia, and silicon carbide used in ball milling. Therefore, ceramic balls having a higher hardness than the superhard metal and thus not generating impurities can be used to promote the transfer of heat energy to the superhard metal. If the diameter of the ceramic ball is less than the above-mentioned numerical range, the heat energy transferred to the superhard metal is small, and the size of the superhard metal may decrease while remaining in the rotary kiln for a long time, and if the diameter exceeds the above-mentioned numerical range, there is a problem that the ceramic ball may be crushed and generate impurities.

[0054] According to another embodiment of the present invention, a superhard metal oxide composite manufactured by the above manufacturing method is provided.

[0055]

[0056] Hereinafter, the present invention will be described in more detail through examples. These examples are intended solely to illustrate the present invention more specifically, and it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples, in accordance with the gist of the present invention.

[0057]

[0058] Examples and Comparative Examples

[0059] Example 1: Preparation of a superhard metal oxide composite 1

[0060] A hydrochloric acid solution having a mol% according to Table 1 was added to 100 g of waste hardened metal, 5 times the amount of waste hardened metal, and the waste hardened metal was immersed in the solution, and surface oxidation of the waste hardened metal was performed for 30 minutes. The surface-oxidized waste hardened metal was heated in a box-type electric furnace at 500 to 1000°C for 1 to 6 hours, thereby obtaining a hardened metal oxide composite.

[0061] No. of manufactured superhard metal oxide composites. Waste superhard metal (g) Hydrochloric acid aqueous solution mol% Reaction temperature in box-type electric furnace (℃) Reaction time in box-type electric furnace (hr) 1100g 11500 12 100g 6500 33 100g 3500 54 100g 11700 25 100g 6700 46 100g 3700 67 100g 11900 28 100g 6900 49 100g 3900 6

[0062] Example 2: Preparation of a superhard metal oxide composite

[0063] 100 g of waste hard metal was immersed in a 3 to 11 mol% hydrochloric acid aqueous solution 5 times the amount of waste hard metal, and surface oxidation of the waste hard metal was performed for 30 minutes. The surface-oxidized waste hard metal was placed in a rotary kiln, and ceramic balls were placed in a weight ratio of 10 to 50 based on the weight of the waste hard metal, and the hard metal was heated in the rotary kiln at 500 to 1000°C for 1 to 6 hours to obtain a hard metal oxide composite.

[0064] No. of manufactured superhard metal oxide composites. Waste superhard metal (g) Hydrochloric acid aqueous solution mol% Ceramic ball (g) (relative to 100g of waste superhard metal) Reaction temperature in rotary kiln (℃) Reaction time in rotary kiln (hr) 10 100g 3 20 7004 11 100g 3 0 7004 12 100g 3 4 0 7004 13 100g 6 20 7004 14 100g 6 30 7004 15 100g 6 4 0 7004 16 100g 1 1 2 7004 17 100g 1 1 3 0 7004 18 100g 1 1 4 0 7004

[0065] Comparative example

[0066] According to Korean Patent Registration No. 10-1020704, in the case of waste hard metal heat-treated in an air atmosphere at 700°C for 5 hours, if you look at the SEM photos of Figures 2a and 2b of the document, you can see that, unlike in the present invention, columnar and irregular particles are not clearly distinguished.

[0067]

[0068] Experimental example

[0069] After separating 100 g of the superhard metal oxide composite manufactured in the above example, it was mixed with sodium carbonate (NaCO3) at a weight ratio of 1:0.7, placed in a box-type electric furnace, and melted at high temperature at 900°C for 6 hours in an air atmosphere. After cooling to room temperature, it was dissolved in water (dissolution water), filtered, and the g of the remaining metal was measured.

[0070] No. of manufactured superhard metal oxide composites. Amorphous particles (g)Columnar particles (g)Oxygen content of columnar particles (based on total weight of columnar particles)Residual metal (g)103070810112575810122080810132080781418827815158578161585651715856518109065

Claims

1. Columnar particles having at least one rounded shape and A superhard metal oxide composite comprising amorphous particles present on at least a portion of the surface of the columnar particles.

2. In claim 1, The above columnar particles are a superhard metal oxide composite in which the average diameter of the cross-section perpendicular to the longitudinal direction is not constant.

3. In claim 1, The above columnar particles and the above amorphous particles contain tungsten (W), cobalt (Co) and oxygen (O), A superhard metal oxide composite wherein the weight % of oxygen (O) atoms contained in the above columnar particles is lower than the weight % of oxygen (O) atoms contained in the above amorphous particles.

4. A step of immersing the hard metal in an acidic solution to oxidize at least a portion of the hard metal; A step of heating the above oxidized superhard metal; and A method for producing a superhard metal oxide composite, comprising a step of obtaining an oxide of the above-mentioned heated superhard metal.

5. In claim 4, A method for producing a superhard metal oxide composite, wherein the acidic solution comprises at least one selected from the group consisting of hydrogen peroxide (H2O2), hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), and perchloric acid (HClO4).

6. In claim 5, A method for producing a superhard metal oxide composite, wherein the pH of the acidic solution is 1 to 3.

7. In claim 4, A method for producing a superhard metal oxide composite, wherein the step of heating the oxidized superhard metal is performed at 500 to 1000°C for 1 to 6 hours.

8. In claim 4, A method for manufacturing a superhard metal oxide composite, wherein the step of heating the above-mentioned oxidized superhard metal uses a rotary kiln.

9. In claim 8, A method for manufacturing a superhard metal oxide composite, wherein the superhard metal is heated together with ceramic balls having a diameter of 5 to 50 mm using a rotary kiln in the step of heating the oxidized superhard metal.

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