WO2020060062A1 - Ceramic element using metal oxide and method for manufacturing same - Google Patents

Ceramic element using metal oxide and method for manufacturing same Download PDF

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Publication number
WO2020060062A1
WO2020060062A1 PCT/KR2019/011055 KR2019011055W WO2020060062A1 WO 2020060062 A1 WO2020060062 A1 WO 2020060062A1 KR 2019011055 W KR2019011055 W KR 2019011055W WO 2020060062 A1 WO2020060062 A1 WO 2020060062A1
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ceramic
metal
metal oxide
core
heat treatment
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PCT/KR2019/011055
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French (fr)
Korean (ko)
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정순종
임동환
구보근
김민수
김인성
신동진
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한국전기연구원
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Priority claimed from KR1020190104197A external-priority patent/KR20200033167A/en
Application filed by 한국전기연구원 filed Critical 한국전기연구원
Publication of WO2020060062A1 publication Critical patent/WO2020060062A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/018—Dielectrics
    • H01G4/06—Solid dielectrics
    • H01G4/08—Inorganic dielectrics
    • H01G4/12—Ceramic dielectrics
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/30—Stacked capacitors

Definitions

  • the present invention relates to a ceramic element using a metal oxide and a method for manufacturing the same, and more specifically, the metal oxide during the heat treatment using a metal oxide does not cause a reaction to prevent oxidation and shrinkage and expansion, while forming a nanoporous structure for electrical conductivity. It relates to an excellent ceramic element and a method for manufacturing the same.
  • the ceramic element is capable of miniaturization and light weight with quick response and precision, so its application is expanding to micro displacement control devices, valves, and pumps.
  • the ceramic element has a smaller displacement than the electric element, and thus has limitations.
  • a multilayer ceramic element in which a thin ceramic film including an internal electrode is stacked in multiple layers has been developed.
  • Such a multilayer ceramic element is manufactured by first forming a ceramic material in a thin film form, forming an electrode with a material as a conductor on the surface of the ceramic film, and then stacking a plurality of ceramic films on which the electrode is formed. At this time, since the laminated ceramic film has a weak strength, it is hardened through heat treatment.
  • the prior art related to a multilayer ceramic element includes a method of manufacturing a multilayer ceramic using a metal powder coated with glass (registration number: 10-1028117), in this case, coating the glass on the surface of the metal powder to form an electrode. And, applying a glass-coated metal powder on the surface of the ceramic film and then stacking a plurality of ceramic films, and heat-treating the ceramic film at high temperature to cure the ceramic material and melt the glass to form an internal electrode to expose the metal powder. It is made to include.
  • the present invention was invented in order to solve the above-mentioned problems, and a metal oxide is used to form a nanoporous structure while preventing the contraction and expansion of metal oxide during heat treatment using a metal oxide, thereby preventing the oxidation of metal. It is an object to provide a ceramic element and a manufacturing method thereof.
  • the present invention for achieving the above object is to form a core-shell powder consisting of a core and a shell made of a metal and one or more metal oxides selected from the group consisting of copper oxide and nickel oxide; Forming a paste by coating glass on the surface of the core-shell powder and then mixing with a binder; Forming the ceramic laminate by printing and laminating the paste on a ceramic tape; First heat-treating the ceramic laminate under an oxidizing atmosphere; And the first heat-treated ceramic laminate is subjected to a second heat treatment under a reducing atmosphere containing hydrogen, thereby reducing oxygen to the metal as oxygen is separated from the metal oxide, and voids are formed in the portion where the oxygen is separated, so that the reduced metal is nano.
  • the first heat treatment includes: degreasing the binder through a binder-burn-out at 100 to 600 ° C .; And sintering the ceramic burned-out ceramic laminate at 900 to 1,000 ° C.
  • the secondary heat treatment to 300 ⁇ 500 °C under a mixed atmosphere of hydrogen and nitrogen.
  • the size of pores generated in the reduced metal increases.
  • a ceramic tape for achieving the above object, a ceramic tape; And a core made of one or more metal oxides selected from the group consisting of copper oxide and nickel oxide and a shell surrounding the core, coated with glass on the surface, and then printed on the ceramic tape in a mixed state with a binder.
  • Electrode including a ceramic laminate to be stacked in a multi-layer structure, the ceramic laminate, after the primary heat treatment in an oxidizing atmosphere, the secondary heat treatment in a reducing atmosphere, the oxygen is separated from the metal oxide while being reduced to metal ,
  • a ceramic element using a metal oxide is characterized in that the reduced metal has a nanoporous structure by generating voids in a portion where the oxygen is separated.
  • the ceramic element using the metal oxide according to the present invention and a method for manufacturing the same according to the above-described solving means have the following effects.
  • the metal oxide is reduced to the metal through heat treatment, voids are formed in the place where oxygen is present, so that the reduced metal has a nanoporous structure, thereby increasing the electrical conductivity to obtain a ceramic device having excellent electrical conductivity.
  • FIG. 1 is a ceramic device according to a preferred embodiment of the present invention.
  • FIG. 2 is a process diagram according to a preferred embodiment of the present invention.
  • Figure 3 is a simultaneous firing process diagram according to a preferred embodiment of the present invention.
  • FIG. 5 is a graph of FIG. 3.
  • Figure 6 is a SEM photograph showing the porous properties of copper by the secondary heat treatment temperature according to a preferred embodiment of the present invention.
  • FIG. 7 is a graph showing a change in electrical resistance due to a secondary heat treatment temperature according to a preferred embodiment of the present invention.
  • the ceramic stacked body 100 in which a plurality of ceramic tapes 110 on which the electrodes 120 are printed (or printed) is stacked is made of a multilayer piezoelectric ceramic element.
  • the ceramic element of the present invention is composed of a ceramic tape 110, a core made of a metal oxide, and a shell surrounding the core, which is coated with glass, and then printed on the ceramic tape 110 in a mixed state with a binder.
  • a ceramic laminate 100 stacked in a multi-layered structure including 120 and the ceramic laminate 100 is first heat-treated under an oxidizing atmosphere and then subjected to a second heat-treatment under a reducing atmosphere to oxygen in the metal oxide. As it is separated, it is reduced to a metal, and the reduced metal has a nanoporous structure by generating voids in a portion where oxygen is separated.
  • the present invention can prevent the contraction and expansion of the electrode by preventing the reaction of the metal being oxidized during the heat treatment by applying a metal oxide as the internal electrode of the ceramic element, and finally the nanoporous structure from the metal oxide. It can be seen that it has characteristics to obtain a reduced metal to have excellent electrical conductivity.
  • the present invention is a core-shell powder preparation step (S10), paste forming step (S20), ceramic laminate forming step (S30), the first heat treatment step (S40) and the second heat treatment step (S50)
  • S10 core-shell powder preparation step
  • S20 paste forming step
  • S30 ceramic laminate forming step
  • S40 first heat treatment step
  • S50 second heat treatment step
  • the core-shell powder preparation step is a step of forming a core-shell powder composed of a core made of metal oxide and a shell made of metal and surrounding the core (S10).
  • AgPd alloys of silver (Ag) or silver (Ag) and palladium (Pd), which have extremely low reactivity, were used to prevent oxidation of the material constituting the electrode, but in particular, Pd began to be used as a catalyst for fuel cells.
  • the AgPd alloy was expensive, so there was a disadvantage that the manufacturing cost increased.
  • a metal oxide obtained by oxidizing a relatively inexpensive and highly conductive metal is used as a core from the beginning, and a core-shell having a core-shell structure surrounding a core with a metal having low reactivity with oxygen as a shell is used. It is to use powder.
  • the core is composed of one or more metal oxide particles selected from the group consisting of copper oxide and nickel oxide.
  • the metal oxide corresponding to the core is copper (Cu), nickel (Ni), and has excellent electrical conductivity and is inexpensive, but it is a metal that oxidizes well (CuO, Cu 2 o), nickel oxide (NiO). It is an oxygen-bonded oxide in the form.
  • the type of the metal oxide is not necessarily limited to the above-described copper oxide or nickel oxide, and various metal oxides can be used, but it is preferable to use copper oxide in terms of electrical conductivity and price.
  • the core is a pure metal such as copper instead of a metal oxide such as copper oxide
  • the glass must be perfectly coated on the surface in the paste forming step to prevent the metal from being oxidized, but it is not easy to process and the glass cannot be coated. Part may occur.
  • a metal is used as a core in this way, there is a problem in that oxidation occurs when oxygen is brought into contact with a portion where the glass is not coated, and thus, it is important for the metal to use a metal oxide combined with oxygen as a core.
  • the shell is composed of metal particles surrounding the surface of the core.
  • the metal corresponding to the shell surrounding the core prevents oxidation of the shell itself while preventing the core from contacting with oxygen in order to prevent shrinkage change due to reduction of metal oxide during secondary heat treatment. It is preferable to select any one or more of silver (Ag) and platinum (Pt) wheat palladium (Pd).
  • the shell acts as an anchor, which prevents metal oxides from contracting during the second heat treatment, and at the same time, reduces the metal oxides by allowing the hydrogen to meet the oxygen to evaporate and stably create voids in the place where the oxygen was. It prevents the swelling of pores in the metal and makes the nanoporous structure stable.
  • the core-shell powder when preparing the core-shell powder, it is preferable to mix 10 to 20 parts by weight of the shell-in metal with respect to 100 parts by weight of the core metal oxide.
  • the metal when the metal is mixed with less than 10 parts by weight, it cannot be used as an electrode due to the occurrence of a large number of breaks due to shrinkage in the metal oxide to be reduced during the subsequent heat treatment, and when the mixture exceeds 20 parts by weight, the thickness of the shell is too high. This is because it may take a long time for the metal oxide disposed on the core to be reduced to the metal.
  • the paste forming step is a step of coating the glass on the surface of the core-shell powder and then forming the paste by mixing with a binder (S20).
  • glass is first made into a glass sol solution and mixed with the core-shell powder to mix the core-shell at room temperature The surface of the powder is coated with glass.
  • the glass sol solution is mixed with respect to 100 parts by weight of the prepared core-shell powder to coat the glass on the surface of the core-shell powder. If the glass sol solution is less than 5 parts by weight, the amount of the core-shell powder may be insufficient to completely coat the surface, and if it exceeds 15 parts by weight, the coating does not exhibit an excellent effect compared to the case of using an amount of less than, and the maximum When 15 parts by weight, the glass is sufficiently coated on the core-shell powder.
  • the glass sol solution is preferably a boric acid-based solution, but is not limited thereto.
  • a binder such as an organic material is mixed to form a paste so that it can be printed on a ceramic tape to finish this step.
  • the step of forming the ceramic laminate is a step of forming a ceramic laminate by printing and laminating the paste on the ceramic tape (S30).
  • a ceramic laminate is prepared by repeating the process of applying a paste of a mixture of core-shell powder and an organic material, which is a binder, along the electrode pattern, where the electrode is to be formed on the surface of the ceramic tape, and stacking the ceramic tape again thereon.
  • the first heat treatment step is a step of first heat treatment of the ceramic laminate under an oxidizing atmosphere (S40).
  • FIG. 3 is a simultaneous firing process diagram according to a preferred embodiment of the present invention
  • FIG. 4 is a SEM photograph of FIG. 3
  • FIG. 5 is a graph of FIG. 3.
  • the first heat treatment step and the second heat treatment step will be described with reference to FIGS. 3 to 5.
  • the graph of FIG. 5 is shown in Table 1 below.
  • Heat treatment conditions 1st heat treatment Binder burnout 150 °C (2h) ⁇ 450 °C (4h) ⁇ 450 °C (6h) ⁇ 550 °C (6h) ⁇ 550 °C (2h) ⁇ cooling Sintering Heating (3 °C / min) ⁇ 950 °C (2 ⁇ 6h) ⁇ cooling [Air] Second heat treatment Heating (3 °C / min) ⁇ 300 ⁇ 500 °C (12h) ⁇ cooling [N 2 / H 2 (95: 5)]
  • the first heat treatment step includes a binder burnout step (S40-1) and a sintering step (S40-2) through heat treatment.
  • the binder burnout step (S40-1) the ceramic laminate is subjected to an oxidizing atmosphere including air.
  • a binder burn-out (BBO) in the range of 100 to 600 ° C
  • the organic material as a binder in the paste contained in the ceramic laminate is heat-treated at a temperature of 100 to 600 ° C under an oxidizing atmosphere. After cooling, it is removed.
  • the binder burnout is performed in a range of 100 to 600 ° C (more preferably 150 to 550 ° C).
  • the type of binder that can be used is limited because the binder burnout process must be performed at around 200 ° C. Because of the use of oxides, the binder burnout process is possible up to a high temperature of 550 ° C. In this way, as the high temperature is possible at the time of burnout of the binder, the present invention has an effect of not limiting the binder to be used for preparing the paste.
  • the core-shell structure surrounded by the metal silver (Ag) on the surface of the metal oxide copper oxide (CuO) can be confirmed, and a schematic view of the organic binder is burned out. You can see that it is shown.
  • FIG. 4- (a) the SEM photograph of FIG. 3- (a) is shown, and it can be seen that copper oxide is maintained and only the organic matter is evaporated through the binder burnout.
  • the sintering step (S40-2) is a process of sintering the ceramic stacked body with the binder burned out under an oxidizing atmosphere including air at 900 to 1,000 ° C for 2 to 6 hours. It takes, and if it exceeds 1,000 ° C, it is important to make it below 1,000 ° C to prevent this because the core-shell powder may melt.
  • the core CuO is sintered and the shell Ag is located at the grain boundary of CuO and schematically shows the sintered state around CuO.
  • FIG. 4- (b) the SEM photograph of FIG. 3- (b) is shown, and it can be confirmed that both CuO and Ag were sintered in the same process as [Equation 1] below. As shown in FIGS. 3- (b) and 4- (b), it can be seen that densification of the ceramic and the electrode is achieved through the sintering step.
  • the core is made of a metal other than a metal oxide
  • a part of the core metal may be oxidized, and the core becomes a metal oxide in the metal. If thrown away, the metal shrinks or expands, causing the electrode to break or bend. For this reason, in the present invention, the metal is oxidized in advance as a core to prevent metal expansion or contraction by heat treatment.
  • the primary heat treatment step for binder burnout and sintering is performed under an oxidizing atmosphere, which may mean an air atmosphere containing some oxygen or an atmosphere in which an inert gas such as nitrogen or argon is mixed with oxygen.
  • an oxidizing atmosphere which may mean an air atmosphere containing some oxygen or an atmosphere in which an inert gas such as nitrogen or argon is mixed with oxygen.
  • the properties of the ceramic laminate may be maintained, but there is a problem in that the metal powder is oxidized, and thus it is generally performed under an inert gas atmosphere.
  • the inert gas may be mixed in an amount of 0.1 to 99% by volume, and oxygen may be in an atmosphere of 1 to 99.9% by volume.
  • the first heat-treated ceramic laminate is subjected to a second heat treatment under a reducing atmosphere, whereby metal oxides are reduced to metals, and voids are generated, and the metals reduced by the pores have a nanoporous structure. It is a step (S50).
  • the first heat-treated ceramic laminate is subjected to a second heat treatment under a reducing atmosphere containing hydrogen, whereby oxygen is separated from the metal oxide and reduced to metal. It is a process that is characterized by the present invention by having a porous structure.
  • the ceramic laminate in order to reduce the metal oxide to metal so as to exhibit electrical properties, is mixed with hydrogen and nitrogen at a temperature lower than the first heat treatment at 300 to 500 ° C and hydrogen (N 2 / H 2 gas).
  • hydrogen N 2 / H 2 gas
  • CuO copper oxide
  • CuO copper oxide
  • the reduction of the metal oxide is achieved through the second heat treatment step, and the place where oxygen was generated while the metal oxide was reduced through the second heat treatment.
  • a nanoporous reducing metal having a nanoporous structure is formed thereon.
  • the secondary heat treatment is performed under a reducing atmosphere to recover the metal oxide as a metal having a nanoporous structure, and thereby forming a Cu / Ag structure having a nanoporous structure, thereby improving the characteristics of the ceramic device.
  • the metal powder is partially oxidized even under an inert gas atmosphere, in the present invention, a pre-oxidized metal oxide is used, and the second heat treatment is performed under a reducing atmosphere, which is the present step, without reducing the properties of the ceramic tape by reducing it. It is to form a ceramic device having very excellent properties.
  • the secondary heat treatment it is preferable to be performed at 300 to 500 ° C. It may be possible at less than 300 ° C. If it exceeds 500 ° C, the ceramic laminate may react with hydrogen to change its properties. In the heat treatment should be done.
  • FIG. 6- (a) is 300 ° C.
  • FIG. 6- (b) is 400 ° C.
  • FIG. 6- (c) is a SEM image of copper after the second heat treatment at 500 ° C., and the temperature is 300 ° C. From it can be seen that the size of the pores increases as the temperature goes to 500 ° C.
  • FIG. 7 is a graph showing a change in electrical resistance due to a secondary heat treatment temperature according to a preferred embodiment of the present invention.
  • insulation resistance is measured using a high resistance, and shows a change in electrical resistance of a ceramic device according to a secondary heat treatment temperature. As a result, it was confirmed that the resistance of the ceramic did not change significantly within the secondary heat treatment temperature range.
  • FIG. 8 is a conductivity diagram of an electrode after secondary heat treatment according to a preferred embodiment of the present invention. Referring to FIG. 8, it can be seen that the conductivity of the electrode (CuO with reduced CuAg) of the present invention compared to a Bulk Cu, Bulk Ag, or AgPd alloy is measured. According to FIG. 8, it was confirmed that the electrical conductivity of the electrode of the present invention is almost similar to the electrical conductivity of the Bulk Cu, Bulk Ag, and AgPd alloys.
  • a borosilicate glass precursor was used.
  • the sol-form borosilicate glass precursor solution was mixed with the copper oxide powder, and then the copper oxide solution was added to a mixture of 6.3 mL oleic acid and 40 mL acetone.
  • the mixed solution was stirred at room temperature for 90 minutes, then heated at about 70 ° C for 2 hours, and washed with acetone. Then, the mixed solution was dried in an oven at about 80 ° C. to obtain a core-shell powder composed of copper oxide-silver.
  • Silver nitrate (AgNO 3 , 0.003M) was mixed with 50 mL of distilled water, and ammonium hydroxide (NH 4 OH) was added dropwise using a syringe. At this time, 1 drop of ammonia was added to make the transparent solution turn brown. If more ammonia was added, it became a transparent solution.
  • This solution was diluted with the addition of 50 mL distilled water. The diluted 200 mL solution was mixed with 200 mg of copper oxide powder, and then added to a solution containing 0.036 g of cetyltrimethylammonium bromide (CTAB) in 5 mL of DI water. The mixed solution was stirred and sonicated for 10 minutes.
  • CTAB cetyltrimethylammonium bromide
  • the mixed solution was mixed and stirred with 50 mL of distilled water containing 0.18 g of glucose, and heated to 120 ° C. for 30 minutes.
  • copper (CuO) coated with silver (Ag) on the surface of the core-shell metal oxide was obtained.
  • CuO-Ag powders were mixed with a solution of a borosilicate glass precursor, and then the solution was heated at 120 ° C. for 3 hours to form a glass-coated CuO-Ag powder. Subsequently, CuO-Ag powder was mixed with an organic material (Ferro Co. 75001 or ⁇ -terpinol) in a weight ratio of 6: 4 to form an electrode paste. At this time, it was confirmed that the CuO-Ag powder has a uniform particle distribution having an average diameter of 2 ⁇ m.
  • an organic material Ferro Co. 75001 or ⁇ -terpinol
  • a ceramic laminate was formed by repeating the process of applying the prepared internal electrode paste on the surface of the ceramic tape on the surface of the electrode to be formed along the electrode pattern, and then stacking the ceramic tape thereon.
  • BNST (Bi 0.37 Na 0.37 Sr 0.26 ) TiO 3
  • BNST a ceramic tape having 1% additive CuO.
  • BNST represents the transition from the relaxation group to the ferroelectric layer by applying an electric field, and it involves a large mechanical deformation, and this BNST is ferroelectric by applying an electric field (up to 4 kV / mm) with a large deformation behavior (> 0.2% strain).
  • the micro-domain shows the return of the nanopole region.
  • Binder burnout was performed by heat treatment at 150 ° C. for 2 hours to remove the organic material, followed by heating at 450 ° C. for 4 hours and heating at 550 ° C. for 6 hours. Thereafter, the sample was heated to 950 ° C at a rate of 9 ° C / min in air and then sintered by holding at 950 ° C for 4 hours. As a work-up, the sample was heated to 300 ° C. at a rate of 3 ° C./min under an H 2 / N 2 (5:95 volume ratio) atmosphere and then maintained at 300 ° C. for 6 hours.
  • FIG. 9 is a graph of polarization and strain-field curves for a ceramic device.
  • AgPd / BNST according to Comparative Example 1 and CuO-Ag / BNST according to Example 1 showed almost the same unipolar and bipolar strain and polarization behavior as shown in FIG. 9. That is, the result of using a CuAg electrode in which CuO-Ag is reduced along with a lead-free ceramic BNST means that the production of a multilayer ceramic element can be produced by a simultaneous firing process in air.
  • the present invention does not cause a phenomenon in which the electrode is bent, cracked, or broken during the heat treatment process using the core-shell powder, and oxygen is removed while oxygen is removed from the metal oxide by finally reducing the core-shell powder.
  • a metal having a nanoporous structure in which voids are formed will be formed at the site.

Abstract

The present invention relates to a ceramic element using a metal oxide and a method for manufacturing same and, more specifically, to a ceramic element in which a metal oxide is employed so as to protect the metal against oxidation during thermal treatment and thus has a nanoporous structure while preventing the shrinkage and expansion thereof, and a method for manufacturing same. The present invention provides a multilayered ceramic laminate comprising: a ceramic tape; and an electrode that comprises a core including at least one metal oxide selected from the group consisting of copper oxide and nickel oxide, and a shell including a metal and sheathing the core and which is coated with glass on the surface thereof and then printed in mixture with a binder on the ceramic tape. The technical gist of the present invention lies in the feature that when the ceramic laminate is subjected to secondary thermal treatment in a reductant atmosphere after a primary thermal treatment in an oxidative atmosphere, the metal oxide is reduced to a metal with the segregation of oxygen therefrom and the concomitant generation of pores at the oxygen-segregated portions, whereby the reduced metal has a nanoporous structure.

Description

금속산화물을 이용한 세라믹소자 및 이의 제조방법Ceramic element using metal oxide and method for manufacturing the same
본 발명은 금속산화물을 이용한 세라믹소자 및 이의 제조방법에 관한 것으로, 더욱 상세하게는 금속산화물을 이용해 열처리 중에 금속이 산화되는 반응이 일어나지 않아 수축 및 팽창을 방지하면서 나노포러스 구조의 형성으로 전기전도성이 우수한 세라믹소자와, 이를 제조하는 방법에 관한 것이다.The present invention relates to a ceramic element using a metal oxide and a method for manufacturing the same, and more specifically, the metal oxide during the heat treatment using a metal oxide does not cause a reaction to prevent oxidation and shrinkage and expansion, while forming a nanoporous structure for electrical conductivity. It relates to an excellent ceramic element and a method for manufacturing the same.
세라믹소자는 빠른 응답성과 정밀성을 가지고 소형 경량화가 가능하여 미소변위 제어장치, 밸브 및 펌프 등에 그 응용성이 확대되고 있는 추세이다.The ceramic element is capable of miniaturization and light weight with quick response and precision, so its application is expanding to micro displacement control devices, valves, and pumps.
하지만 세라믹소자는 전기식 소자보다 변위가 작아 한계성을 보이고 있는데, 이를 극복하기 위해서 내부전극을 포함한 얇은 세라믹 막을 여러층 겹친 적층형 세라믹소자가 개발되고 있다.However, the ceramic element has a smaller displacement than the electric element, and thus has limitations. In order to overcome this, a multilayer ceramic element in which a thin ceramic film including an internal electrode is stacked in multiple layers has been developed.
이러한 적층형 세라믹소자는 먼저 세라믹재료를 얇은 막 형태로 만들고, 세라믹 막의 표면에 전도체인 물질로 전극을 형성한 후, 전극이 형성된 세라믹 막을 다수 개 적층하는 방식으로 제조된다. 이때 적층된 세라믹 막은 강도가 약하기 때문에 열처리를 통하여 단단하게 경화시키게 된다.Such a multilayer ceramic element is manufactured by first forming a ceramic material in a thin film form, forming an electrode with a material as a conductor on the surface of the ceramic film, and then stacking a plurality of ceramic films on which the electrode is formed. At this time, since the laminated ceramic film has a weak strength, it is hardened through heat treatment.
적층형 세라믹소자와 관련된 종래기술로는 '유리를 코팅한 금속분말을 사용한 적층형 세라믹 제조방법(등록번호: 10-1028117)'이 있는데, 이 경우 전극을 이루게 될 금속분말의 표면에 유리를 코팅하는 단계와, 세라믹 막의 표면에 유리가 코팅된 금속분말을 도포한 후 세라믹 막을 다수 개 적층하는 단계와, 세라믹 막을 고온에서 열처리하여 세라믹재료를 경화시키고 유리를 녹여 금속분말이 노출되도록 내부전극을 형성하는 단계를 포함하도록 이루어져 있다.The prior art related to a multilayer ceramic element includes a method of manufacturing a multilayer ceramic using a metal powder coated with glass (registration number: 10-1028117), in this case, coating the glass on the surface of the metal powder to form an electrode. And, applying a glass-coated metal powder on the surface of the ceramic film and then stacking a plurality of ceramic films, and heat-treating the ceramic film at high temperature to cure the ceramic material and melt the glass to form an internal electrode to expose the metal powder. It is made to include.
하지만 이와 같이 경화를 위해 세라믹 막과 내부전극이 적층된 세라믹소자를 열처리할 경우 전극에 존재하는 금속분말의 일부가 산화되어 금속산화물로 변형되면서 내부전극이 부피 팽창을 하게 된다.However, when heat-treating a ceramic element in which a ceramic film and an internal electrode are stacked for curing, a portion of the metal powder present in the electrode is oxidized and transformed into a metal oxide, thereby expanding the internal electrode.
상술된 이유로, 금속산화물로 인해 내부전극이 부피 팽창을 하게 되면 내부전극과 세라믹 막 사이에 수축률 변화가 발생하고, 이에 따라 세라믹소자에 기계적인 응력이 발생되면서 부서지거나 휘어지는 문제점이 있다.For the above-described reason, when the internal electrode undergoes bulk expansion due to the metal oxide, a shrinkage rate change occurs between the internal electrode and the ceramic film, and accordingly, a mechanical stress is generated in the ceramic element, and thus there is a problem of breaking or bending.
또한 세라믹 막과 내부전극의 동시 열처리 중에 내부전극 내 존재하는 금속분말 일부가 세라믹 막 쪽으로 확산되어 세라믹 막의 절연특성이 감소되는 문제점도 있다.In addition, there is a problem in that, during the simultaneous heat treatment of the ceramic film and the internal electrode, a part of the metal powder existing in the internal electrode diffuses toward the ceramic film and the insulating properties of the ceramic film are reduced.
따라서 전극의 수축 및 팽창을 방지할 수 있을 뿐만 아니라, 최종적으로 전기전도성을 증가시킬 수 있도록 하는 세라믹소자에 대한 기술개발 연구가 절실히 요구되는 시점이다.Therefore, not only can the electrode not only be prevented from contracting and expanding, but also, it is a time when research and development on the ceramic device to finally increase the electrical conductivity is urgently required.
본 발명은 상기한 문제점을 해소하기 위하여 발명된 것으로, 금속산화물을 이용해 열처리 중에 금속이 산화되는 반응이 일어나지 않아 수축 및 팽창을 방지하면서 나노포러스 구조의 형성으로 전기전도성이 우수하도록 하는 금속산화물을 이용한 세라믹소자 및 이의 제조방법을 제공하는데 그 목적이 있다.The present invention was invented in order to solve the above-mentioned problems, and a metal oxide is used to form a nanoporous structure while preventing the contraction and expansion of metal oxide during heat treatment using a metal oxide, thereby preventing the oxidation of metal. It is an object to provide a ceramic element and a manufacturing method thereof.
상기의 목적을 달성하기 위한 본 발명은, 산화구리, 산화니켈로 이루어진 군에서 선택되는 1종 이상의 금속산화물로 이루어진 코어 및 금속으로 이루어져 상기 코어를 감싸는 쉘로 구성된 코어-쉘 분말을 형성하는 단계; 상기 코어-쉘 분말의 표면에 유리를 코팅한 후 바인더와의 혼합으로 페이스트를 형성하는 단계; 세라믹테이프에 상기 페이스트를 프린팅한 후 적층하여 세라믹적층체를 형성하는 단계; 상기 세라믹적층체를 산화분위기 하에서 1차 열처리하는 단계; 및 상기 1차 열처리된 세라믹적층체를 수소를 포함한 환원분위기 하에서 2차 열처리하여 상기 금속산화물에서 산소가 분리되면서 금속으로 환원되고, 상기 산소가 분리된 부분에 공극이 생성됨으로써 상기 환원된 금속이 나노포러스(nanoporous) 구조를 갖는 단계;를 포함하는 것을 특징으로 하는 금속산화물을 이용한 세라믹소자의 제조방법을 기술적 요지로 한다.The present invention for achieving the above object is to form a core-shell powder consisting of a core and a shell made of a metal and one or more metal oxides selected from the group consisting of copper oxide and nickel oxide; Forming a paste by coating glass on the surface of the core-shell powder and then mixing with a binder; Forming the ceramic laminate by printing and laminating the paste on a ceramic tape; First heat-treating the ceramic laminate under an oxidizing atmosphere; And the first heat-treated ceramic laminate is subjected to a second heat treatment under a reducing atmosphere containing hydrogen, thereby reducing oxygen to the metal as oxygen is separated from the metal oxide, and voids are formed in the portion where the oxygen is separated, so that the reduced metal is nano. A step of having a porous structure (nanoporous); a method for manufacturing a ceramic device using a metal oxide, characterized in that it comprises a technical point.
바람직하게는 상기 1차 열처리하는 단계는, 상기 세라믹적층체를 100~600℃에서 바인더 번아웃(binder-burn-out)을 통해 상기 바인더를 탈지시키는 단계; 및 상기 바인더 번아웃된 세라믹적층체를 900~1,000℃에서 소결하는 단계;를 포함하는 것을 특징으로 한다.Preferably, the first heat treatment includes: degreasing the binder through a binder-burn-out at 100 to 600 ° C .; And sintering the ceramic burned-out ceramic laminate at 900 to 1,000 ° C.
바람직하게는 상기 나노포러스 구조를 갖는 단계에서는, 수소와 질소의 혼합분위기 하에서 300~500℃로 2차 열처리하는 것을 특징으로 한다.Preferably in the step of having the nanoporous structure, it is characterized in that the secondary heat treatment to 300 ~ 500 ℃ under a mixed atmosphere of hydrogen and nitrogen.
바람직하게는 상기 나노포러스 구조를 갖는 단계에서는, 상기 2차 열처리의 온도가 300℃에서 500℃로 갈수록 상기 환원된 금속에 생성되는 공극의 크기가 커지는 것을 특징으로 한다.Preferably, in the step of having the nanoporous structure, as the temperature of the secondary heat treatment increases from 300 ° C to 500 ° C, the size of pores generated in the reduced metal increases.
상기의 목적을 달성하기 위한 본 발명은, 세라믹테이프; 및 산화구리, 산화니켈로 이루어진 군에서 선택되는 1종 이상의 금속산화물로 이루어진 코어 및 금속으로 이루어져 상기 코어를 감싸는 쉘로 구성되어 표면에 유리가 코팅된 후 바인더와 혼합된 상태로 상기 세라믹테이프에 프린팅되는 전극;을 포함하여 다층구조로 적층되는 세라믹적층체이되, 상기 세라믹적층체는, 산화분위기 하에서 1차 열처리된 후, 환원분위기 하에서 2차 열처리될 시 상기 금속산화물에서 산소가 분리되면서 금속으로 환원되고, 상기 산소가 분리된 부분에 공극이 생성됨으로써 상기 환원된 금속이 나노포러스(nanoporous) 구조를 갖는 것을 특징으로 하는 금속산화물을 이용한 세라믹소자를 기술적 요지로 한다.The present invention for achieving the above object, a ceramic tape; And a core made of one or more metal oxides selected from the group consisting of copper oxide and nickel oxide and a shell surrounding the core, coated with glass on the surface, and then printed on the ceramic tape in a mixed state with a binder. Electrode; including a ceramic laminate to be stacked in a multi-layer structure, the ceramic laminate, after the primary heat treatment in an oxidizing atmosphere, the secondary heat treatment in a reducing atmosphere, the oxygen is separated from the metal oxide while being reduced to metal , A ceramic element using a metal oxide is characterized in that the reduced metal has a nanoporous structure by generating voids in a portion where the oxygen is separated.
상기 과제의 해결 수단에 의한 본 발명에 따른 금속산화물을 이용한 세라믹소자 및 이의 제조방법은, 다음과 같은 효과가 있다.The ceramic element using the metal oxide according to the present invention and a method for manufacturing the same according to the above-described solving means have the following effects.
첫째, 세라믹소자의 내부전극으로 금속산화물을 사용함으로써 열처리 중에 금속이 산화되는 반응이 일어나지 않아 전극의 수축 및 팽창을 방지하는 효과가 있다.First, by using a metal oxide as an internal electrode of the ceramic element, there is no effect that the metal is oxidized during heat treatment, thereby preventing the electrode from shrinking and expanding.
둘째, 열처리를 통해 금속산화물이 금속으로 환원되면서 산소가 있던 자리에 공극이 생성되어 환원된 금속이 나노포러스 구조를 가지게 됨으로써, 전기전도도가 증가하여 전기전도성이 우수한 세라믹소자를 얻을 수 있는 효과가 있다.Second, as the metal oxide is reduced to the metal through heat treatment, voids are formed in the place where oxygen is present, so that the reduced metal has a nanoporous structure, thereby increasing the electrical conductivity to obtain a ceramic device having excellent electrical conductivity. .
도 1은 본 발명의 바람직한 실시예에 따른 세라믹소자.1 is a ceramic device according to a preferred embodiment of the present invention.
도 2는 본 발명의 바람직한 실시예에 따른 과정도.2 is a process diagram according to a preferred embodiment of the present invention.
도 3은 본 발명의 바람직한 실시예에 따른 동시 소성 과정도.Figure 3 is a simultaneous firing process diagram according to a preferred embodiment of the present invention.
도 4는 도 3의 SEM 사진.4 is an SEM photograph of FIG. 3.
도 5는 도 3의 그래프.5 is a graph of FIG. 3.
도 6은 본 발명의 바람직한 실시예에 따른 2차 열처리 온도에 의한 구리의 다공성 특성을 나타낸 SEM 사진.Figure 6 is a SEM photograph showing the porous properties of copper by the secondary heat treatment temperature according to a preferred embodiment of the present invention.
도 7은 본 발명의 바람직한 실시예에 따른 2차 열처리 온도에 의한 전기저항 변화를 나타낸 그래프.7 is a graph showing a change in electrical resistance due to a secondary heat treatment temperature according to a preferred embodiment of the present invention.
도 8은 본 발명의 바람직한 실시예에 따른 2차 열처리 후 전극의 전도도.8 is a conductivity of the electrode after the second heat treatment according to a preferred embodiment of the present invention.
도 9는 세라믹소자에 대한 분극 및 변형률-전계곡선 그래프.9 is a graph of polarization and strain-field curves for ceramic elements.
이하, 본 발명의 바람직한 실시예를 첨부한 도면을 참조하여 상세하게 설명하면 다음과 같다.Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.
도 1은 본 발명의 바람직한 실시예에 따른 세라믹소자이다. 도 1을 참조하면, 전극(120)이 프린팅(또는 인쇄)된 세라믹테이프(110)가 다수 개로 적층된 세라믹적층체(100)가 다층 압전 세라믹소자로 이루어짐을 알 수 있다.1 is a ceramic device according to a preferred embodiment of the present invention. Referring to FIG. 1, it can be seen that the ceramic stacked body 100 in which a plurality of ceramic tapes 110 on which the electrodes 120 are printed (or printed) is stacked is made of a multilayer piezoelectric ceramic element.
즉 본 발명의 세라믹소자는 세라믹테이프(110)와, 금속산화물로 이루어진 코어 및 금속으로 이루어져 코어를 감싸는 쉘로 이루어져 표면에 유리가 코팅된 후 바인더와 혼합된 상태로 세라믹테이프(110)에 프린팅되는 전극(120)을 포함하여 다층구조로 적층되는 세라믹적층체(100)를 의미하는 것으로, 세라믹적층체(100)는 산화분위기 하에서 1차 열처리된 후, 환원분위기 하에서 2차 열처리될 시 금속산화물에서 산소가 분리되면서 금속으로 환원되고, 산소가 분리된 부분에 공극이 생성됨으로써 환원된 금속이 나노포러스(nanoporous) 구조를 갖는다.That is, the ceramic element of the present invention is composed of a ceramic tape 110, a core made of a metal oxide, and a shell surrounding the core, which is coated with glass, and then printed on the ceramic tape 110 in a mixed state with a binder. Refers to a ceramic laminate 100 stacked in a multi-layered structure including 120, and the ceramic laminate 100 is first heat-treated under an oxidizing atmosphere and then subjected to a second heat-treatment under a reducing atmosphere to oxygen in the metal oxide. As it is separated, it is reduced to a metal, and the reduced metal has a nanoporous structure by generating voids in a portion where oxygen is separated.
이러한 도 1에 의하면, 본 발명은 세라믹소자의 내부전극으로 금속산화물을 적용하여 열처리 중에 금속이 산화되는 반응이 일어나지 않아 전극의 수축 및 팽창을 방지할 수 있으며, 금속산화물로부터 최종적으로 나노포러스 구조를 갖는 환원된 금속을 얻어 전기전도성이 우수하도록 하는데 특징이 있음을 알 수 있다.According to this FIG. 1, the present invention can prevent the contraction and expansion of the electrode by preventing the reaction of the metal being oxidized during the heat treatment by applying a metal oxide as the internal electrode of the ceramic element, and finally the nanoporous structure from the metal oxide. It can be seen that it has characteristics to obtain a reduced metal to have excellent electrical conductivity.
도 2는 본 발명의 바람직한 실시예에 따른 과정도이다. 도 2를 참조하면, 본 발명은 코어-쉘 분말 준비단계(S10), 페이스트 형성단계(S20), 세라믹적층체 형성단계(S30), 1차 열처리단계(S40) 및 2차 열처리단계(S50)를 거침으로써, 금속산화물이 금속으로 환원되면서 공극을 생성시켜 나노포러스 구조를 가지게 되는 특징이 달성될 수 있으며, 각각의 단계에 대한 설명은 아래에서 더욱 상세하게 해보고자 한다.2 is a process diagram according to a preferred embodiment of the present invention. 2, the present invention is a core-shell powder preparation step (S10), paste forming step (S20), ceramic laminate forming step (S30), the first heat treatment step (S40) and the second heat treatment step (S50) By passing through, metal oxides are reduced to metals, thereby generating voids, thereby achieving a nanoporous structure, and the description of each step will be described in more detail below.
먼저, 코어-쉘 분말 준비단계는 금속산화물로 이루어진 코어 및 금속으로 이루어져 코어를 감싸는 쉘로 구성된 코어-쉘 분말을 형성하는 단계이다(S10).First, the core-shell powder preparation step is a step of forming a core-shell powder composed of a core made of metal oxide and a shell made of metal and surrounding the core (S10).
우선 세라믹소자의 내부전극으로 금속산화물을 적용한 이유는 다음과 같이 설명될 수 있다.First, the reason for applying the metal oxide as the internal electrode of the ceramic element can be explained as follows.
종래의 경우에는 세라믹적층체를 열처리할 때 금속이 산화되는 것을 방지하기 위해 환원분위기에서 바로 열처리하였으나, 이는 반대로 말하면 산화물로 이루어진 세라믹적층체가 환원된다는 단점이 있었다.In the conventional case, when heat-treating the ceramic laminate, it was directly heat-treated in a reducing atmosphere to prevent metal from being oxidized, but in other words, there was a disadvantage that the ceramic laminate made of oxide is reduced.
또한 전극을 이루는 물질의 산화를 방지하기 위하여 반응성이 극히 낮은 은(Ag) 또는 은(Ag)과 팔라듐(Pd)의 AgPd 합금 등을 사용하였으나, 특히 Pd이 연료전지의 촉매로 사용되기 시작하면서 Ag 또는 AgPd 합금은 고가이므로 제조비용이 증가한다는 단점이 있었다.In addition, AgPd alloys of silver (Ag) or silver (Ag) and palladium (Pd), which have extremely low reactivity, were used to prevent oxidation of the material constituting the electrode, but in particular, Pd began to be used as a catalyst for fuel cells. Alternatively, the AgPd alloy was expensive, so there was a disadvantage that the manufacturing cost increased.
이런 이유로, 본 발명에서는 상대적으로 저렴하면서 전도성이 높은 금속을 산화시킨 금속산화물을 처음부터 코어로 사용하는 것이고, 코어의 표면에 산소와 반응성이 낮은 금속을 쉘로 하여 둘러싼 코어-쉘 구조의 코어-쉘 분말을 사용하는 것이다.For this reason, in the present invention, a metal oxide obtained by oxidizing a relatively inexpensive and highly conductive metal is used as a core from the beginning, and a core-shell having a core-shell structure surrounding a core with a metal having low reactivity with oxygen as a shell is used. It is to use powder.
첫째, 코어는 산화구리, 산화니켈로 이루어진 군에서 선택되는 1종 이상의 금속산화물 입자로 이루어진 구성이다.First, the core is composed of one or more metal oxide particles selected from the group consisting of copper oxide and nickel oxide.
코어(core)에 해당하는 금속산화물은 구리(Cu), 니켈(Ni)과 같이 전기전도성이 우수하고 가격이 저렴하지만 산화가 잘되는 금속을 산화구리(CuO, Cu2o), 산화니켈(NiO)과 같은 형태로 산소화 결합한 산화물이다.The metal oxide corresponding to the core is copper (Cu), nickel (Ni), and has excellent electrical conductivity and is inexpensive, but it is a metal that oxidizes well (CuO, Cu 2 o), nickel oxide (NiO). It is an oxygen-bonded oxide in the form.
금속산화물의 종류로는 반드시 상술된 산화구리나 산화니켈에 한정되는 것만은 아니고 다양한 금속산화물의 사용이 가능하나, 전기전도성 및 가격 측면에서 산화구리를 사용하는 것이 바람직하다.The type of the metal oxide is not necessarily limited to the above-described copper oxide or nickel oxide, and various metal oxides can be used, but it is preferable to use copper oxide in terms of electrical conductivity and price.
만약 코어로 산화구리와 같은 금속산화물이 아닌 구리와 같은 순수 금속을 사용하게 되면, 금속이 산화되지 못하도록 페이스트 형성단계에서 유리를 그 표면에 완벽하게 코팅해야 하나, 공정상 쉽지 않아 유리가 코팅되지 못하는 부분이 발생할 수 있다. 이렇게 코어로 금속을 사용하게 될 경우, 유리가 코팅되지 못한 부분에 산소가 접촉되면서 산화가 발생하는 문제점이 있으므로, 코어로 금속이 산소와 결합한 금속산화물을 사용하는데 중요한 의미가 있다.If the core is a pure metal such as copper instead of a metal oxide such as copper oxide, the glass must be perfectly coated on the surface in the paste forming step to prevent the metal from being oxidized, but it is not easy to process and the glass cannot be coated. Part may occur. When a metal is used as a core in this way, there is a problem in that oxidation occurs when oxygen is brought into contact with a portion where the glass is not coated, and thus, it is important for the metal to use a metal oxide combined with oxygen as a core.
둘째, 쉘은 코어의 표면을 감싸는 금속 입자로 이루어진 구성이다.Second, the shell is composed of metal particles surrounding the surface of the core.
즉 코어의 주위를 둘러싸는 쉘(shell)에 해당하는 금속은 2차 열처리 시 금속산화물의 환원으로 수축률 변화를 예방하기 위한 차원에서 코어를 산소와의 접촉을 차단하면서 쉘 자체도 산화가 잘 일어나지 않도록 하는 은(Ag), 백금(Pt) 밀 팔라듐(Pd) 중 어느 하나 이상을 선택하는 것이 바람직하다.That is, the metal corresponding to the shell surrounding the core prevents oxidation of the shell itself while preventing the core from contacting with oxygen in order to prevent shrinkage change due to reduction of metal oxide during secondary heat treatment. It is preferable to select any one or more of silver (Ag) and platinum (Pt) wheat palladium (Pd).
특히 쉘은 앵커 역할을 하는데, 2차 열처리 시 금속산화물이 수축되지 않도록 잡아줌과 동시에 수소가 산소를 만난 물이 증발하면서 산소가 있던 자리에 공극이 안정적으로 생성되도록 해줌으로써, 금속산화물로부터 환원된 금속에 비대한 공극이 뚫리지 않게 하고 나노포러스한 구조를 안정적으로 만들어주게 된다.In particular, the shell acts as an anchor, which prevents metal oxides from contracting during the second heat treatment, and at the same time, reduces the metal oxides by allowing the hydrogen to meet the oxygen to evaporate and stably create voids in the place where the oxygen was. It prevents the swelling of pores in the metal and makes the nanoporous structure stable.
부가적으로 코어-쉘 분말 제조 시, 코어인 금속산화물 100중량부에 대하여 쉘인 금속을 10~20중량부로 혼합하는 것이 바람직하다. 이는 금속이 10중량부 미만으로 혼합되면 추후 열처리되는 과정에서 환원되려고 하는 금속산화물에 수축이 발생하여 끊김이 많이 발생함으로 인해 전극으로 사용할 수 없게 되고, 20중량부를 초과하여 혼합하면 쉘의 두께가 너무 두꺼워져 코어에 배치된 금속산화물이 금속으로 환원되기까지 많은 시간이 소요될 수 있기 때문이다.Additionally, when preparing the core-shell powder, it is preferable to mix 10 to 20 parts by weight of the shell-in metal with respect to 100 parts by weight of the core metal oxide. When the metal is mixed with less than 10 parts by weight, it cannot be used as an electrode due to the occurrence of a large number of breaks due to shrinkage in the metal oxide to be reduced during the subsequent heat treatment, and when the mixture exceeds 20 parts by weight, the thickness of the shell is too high. This is because it may take a long time for the metal oxide disposed on the core to be reduced to the metal.
다음으로, 페이스트 형성단계는 코어-쉘 분말의 표면에 유리를 코팅한 후 바인더와의 혼합으로 페이스트를 형성하는 단계이다(S20).Next, the paste forming step is a step of coating the glass on the surface of the core-shell powder and then forming the paste by mixing with a binder (S20).
코어-쉘 구조의 코어-쉘 분말 표면에 유리 코팅으로 금속산화물과 금속의 분리 방지를 위하여, 먼저 유리를 글라스 졸(glass sol) 용액으로 만들고, 이를 코어-쉘 분말과 혼합하여 실온에서 코어-쉘 분말의 표면에 유리가 코팅되도록 한다.To prevent the separation of metal oxides and metals with a glass coating on the surface of the core-shell structured core-shell powder, glass is first made into a glass sol solution and mixed with the core-shell powder to mix the core-shell at room temperature The surface of the powder is coated with glass.
상세하게 설명해 보자면, 코어-쉘 분말의 표면에 유리가 코팅되는 방법으로는 실란과 붕산계 재료를 각각 가수분해하여 B2와 Si가 0.2~12의 몰비로 이루어지도록 SiO2:B2O3로 구성된 글라스 졸 용액을 형성한다.In detail, as a method of coating the surface of the core-shell powder with SiO 2 : B 2 O 3 so that B 2 and Si are formed at a molar ratio of 0.2 to 12 by hydrolyzing silane and boric acid-based materials, respectively. The composed glass sol solution is formed.
이어서 준비된 코어-쉘 분말 100중량부에 대하여 글라스 졸 용액 5~15중량부를 혼합하여 코어-쉘 분말의 표면에 유리를 코팅하게 된다. 글라스 졸 용액이 5중량부 미만이면 코어-쉘 분말의 표면을 완벽하게 코팅하기에 부족한 양일 수 있으며, 15중량부를 초과하면 그 이하의 양을 사용한 경우와 대비하여 코팅에 탁월한 효과가 나타나지 않고, 최대 15중량부면 코어-쉘 분말에 유리가 충분히 코팅된다.Subsequently, 5 to 15 parts by weight of the glass sol solution is mixed with respect to 100 parts by weight of the prepared core-shell powder to coat the glass on the surface of the core-shell powder. If the glass sol solution is less than 5 parts by weight, the amount of the core-shell powder may be insufficient to completely coat the surface, and if it exceeds 15 parts by weight, the coating does not exhibit an excellent effect compared to the case of using an amount of less than, and the maximum When 15 parts by weight, the glass is sufficiently coated on the core-shell powder.
참고로, 코어-쉘 분말에 분산제로 산성염을 소량 첨가하여 코어-쉘 분말이 글라스 졸 용액 내에서 보다 잘 혼합될 수 있도록 하는 것도 고려할 수 있다. 단, 글라스 졸 용액은 붕산계를 사용하는 것이 바람직하나, 이에 한정하지는 않기로 한다.For reference, it is also conceivable to add a small amount of acidic salt as a dispersing agent to the core-shell powder so that the core-shell powder can be better mixed in the glass sol solution. However, the glass sol solution is preferably a boric acid-based solution, but is not limited thereto.
이렇게 코어-쉘 분말의 표면에 유리의 코팅이 완료된 후에는 유기물과 같은 바인더를 혼합하여 세라믹테이프에 인쇄 가능하도록 페이스트 형태로 만들어 본 단계를 마무리한다.After the coating of the glass on the surface of the core-shell powder is completed, a binder such as an organic material is mixed to form a paste so that it can be printed on a ceramic tape to finish this step.
다음으로, 세라믹적층체 형성단계는 세라믹테이프에 페이스트를 프린팅한 후 적층하여 세라믹적층체를 형성하는 단계이다(S30).Next, the step of forming the ceramic laminate is a step of forming a ceramic laminate by printing and laminating the paste on the ceramic tape (S30).
즉 세라믹테이프의 표면 중 전극이 형성될 곳에 코어-쉘 분말과 바인더인 유기물을 혼합한 페이스트를 전극패턴을 따라 도포하고 그 위에 다시 세라믹테이프를 적층하는 과정을 반복하여 세라믹적층체를 제조한다.That is, a ceramic laminate is prepared by repeating the process of applying a paste of a mixture of core-shell powder and an organic material, which is a binder, along the electrode pattern, where the electrode is to be formed on the surface of the ceramic tape, and stacking the ceramic tape again thereon.
다음으로, 1차 열처리단계는 세라믹적층체를 산화분위기 하에서 1차 열처리하는 단계이다(S40).Next, the first heat treatment step is a step of first heat treatment of the ceramic laminate under an oxidizing atmosphere (S40).
도 3은 본 발명의 바람직한 실시예에 따른 동시 소성 과정도이고, 도 4는 도 3의 SEM 사진이며, 도 5는 도 3의 그래프이다. 1차 열처리단계 및 2차 열처리단계는 도 3 내지 도 5를 통하여 설명해 보기로 한다. 도 5의 그래프는 다음과 같은 표 1에 나타내었다.3 is a simultaneous firing process diagram according to a preferred embodiment of the present invention, FIG. 4 is a SEM photograph of FIG. 3, and FIG. 5 is a graph of FIG. 3. The first heat treatment step and the second heat treatment step will be described with reference to FIGS. 3 to 5. The graph of FIG. 5 is shown in Table 1 below.
열처리 조건Heat treatment conditions
1차열처리1st heat treatment 바인더번아웃Binder burnout 150℃(2h)→450℃(4h)→450℃(6h)→550℃(6h)→550℃(2h)→cooling150 ℃ (2h) → 450 ℃ (4h) → 450 ℃ (6h) → 550 ℃ (6h) → 550 ℃ (2h) → cooling
소결Sintering Heating(3℃/min)→950℃(2~6h)→cooling[Air]Heating (3 ℃ / min) → 950 ℃ (2 ~ 6h) → cooling [Air]
2차열처리Second heat treatment Heating(3℃/min)→300~500℃(12h)→cooling[N2/H2(95:5)]Heating (3 ℃ / min) → 300 ~ 500 ℃ (12h) → cooling [N 2 / H 2 (95: 5)]
우선 1차 열처리단계는 열처리를 통한 바인더 번아웃단계(S40-1) 및 소결단계(S40-2)가 포함된다.바인더 번아웃단계(S40-1)는 세라믹적층체를 공기를 포함한 산화분위기 하에서 100~600℃ 범위로 바인더 번아웃(binder-burn-out; BBO)을 통해 바인더를 탈지시키는 과정으로써, 세라믹적층체에 포함된 페이스트 중 바인더인 유기물을 산화분위기 하에서 100~600℃의 온도로 열처리한 후 냉각을 거쳐 제거한다.First, the first heat treatment step includes a binder burnout step (S40-1) and a sintering step (S40-2) through heat treatment. In the binder burnout step (S40-1), the ceramic laminate is subjected to an oxidizing atmosphere including air. As a process of degreasing the binder through a binder burn-out (BBO) in the range of 100 to 600 ° C, the organic material as a binder in the paste contained in the ceramic laminate is heat-treated at a temperature of 100 to 600 ° C under an oxidizing atmosphere. After cooling, it is removed.
100℃ 미만의 조건에서는 바인더가 번아웃되는데 까지 상당한 시간이 소요되어 공정상 비효율적인 측면이 부각되고, 600℃를 초과하는 조건에서는 페이스트가 소결되기 때문에 오히려 탈지가 원활히 이루어지지 않는다. 이런 이유로, 페이스트에 포함된 유기물이 모두 제거되기 위해서는 100~600℃ 범위(더욱 바람직하게는 150~550℃)에서 바인더 번아웃이 이루어지는 것이 바람직하다.Under conditions of less than 100 ° C, it takes considerable time for the binder to be burned out, and thus, an inefficient aspect in the process is highlighted, and under conditions exceeding 600 ° C, the paste is sintered, so that degreasing is not smoothly performed. For this reason, in order to remove all of the organic matter contained in the paste, it is preferable that the binder burnout is performed in a range of 100 to 600 ° C (more preferably 150 to 550 ° C).
기존에 금속으로 이루어진 코어의 사용으로 탈지과정에서 금속이 산화되면 안되기 때문에 바인더 번아웃 공정이 200℃ 내외에서 이루어져야 해서 사용될 수 있는 바인더의 종류가 제한적이었던 것과 달리, 본 발명은 코어로 금속과 다른 금속산화물을 사용가기 때문에 바인더 번아웃 공정이 550℃의 높은 온도까지 가능하다. 이렇게 바인더 번아웃 시 높은 온도가 가능함에 따라, 본 발명에서는 페이스트 제조를 위해 사용되어야 하는 바인더의 제한도 없게 되는 효과가 있다.Unlike the existing metal, which should not be oxidized in the degreasing process by using a core made of metal, the type of binder that can be used is limited because the binder burnout process must be performed at around 200 ° C. Because of the use of oxides, the binder burnout process is possible up to a high temperature of 550 ° C. In this way, as the high temperature is possible at the time of burnout of the binder, the present invention has an effect of not limiting the binder to be used for preparing the paste.
도 3-(a)를 참조하면, 금속산화물인 산화구리(CuO)의 표면에 금속인 은(Ag)이 둘러싸인 코어-쉘 구조를 확인할 수 있으며, 유기물인 바인더가 번아웃된 모습을 모식적으로 나타낸 것임을 알 수 있다.Referring to FIG. 3- (a), the core-shell structure surrounded by the metal silver (Ag) on the surface of the metal oxide copper oxide (CuO) can be confirmed, and a schematic view of the organic binder is burned out. You can see that it is shown.
도 4-(a)를 참조하면, 도 3-(a)의 SEM 사진을 나타낸 것으로, 바인더 번아웃을 통해 산화구리는 유지되고 유기물만이 증발됨을 알 수 있다.Referring to FIG. 4- (a), the SEM photograph of FIG. 3- (a) is shown, and it can be seen that copper oxide is maintained and only the organic matter is evaporated through the binder burnout.
소결단계(S40-2)는 마찬가지로 공기를 포함한 산화분위기 하에서 바인더 번아웃된 세라믹적층체를 2~6시간 동안 900~1,000℃에서 소결하는 과정으로써, 900℃ 미만이면 소결이 완전히 되는데 까지 많은 시간이 소요되고, 1,000℃를 초과하면 코어-쉘 분말이 용융될 수 있기 때문에 이를 방지하기 위하여 1,000℃ 이하로 이루어지게 하는 것이 중요하다.The sintering step (S40-2) is a process of sintering the ceramic stacked body with the binder burned out under an oxidizing atmosphere including air at 900 to 1,000 ° C for 2 to 6 hours. It takes, and if it exceeds 1,000 ° C, it is important to make it below 1,000 ° C to prevent this because the core-shell powder may melt.
도 3-(b)를 참조하면, 코어인 CuO는 소결되고 쉘인 Ag는 CuO의 입계에 위치하여 CuO 주위에서 소결된 모습을 모식적으로 나타낸 것임을 알 수 있다.Referring to FIG. 3- (b), it can be seen that the core CuO is sintered and the shell Ag is located at the grain boundary of CuO and schematically shows the sintered state around CuO.
도 4-(b)를 참조하면, 도 3-(b)의 SEM 사진을 나타낸 것으로, 아래의 [식 1]과 같은 과정으로 CuO와 Ag 모두 소결이 되었음을 확인할 수 있다. 도 3-(b) 및 도 4-(b)에 나타난 바와 같이, 소결단계를 통해 세라믹과 전극의 치밀화가 이루어짐을 알 수 있다.Referring to FIG. 4- (b), the SEM photograph of FIG. 3- (b) is shown, and it can be confirmed that both CuO and Ag were sintered in the same process as [Equation 1] below. As shown in FIGS. 3- (b) and 4- (b), it can be seen that densification of the ceramic and the electrode is achieved through the sintering step.
[식 1] CuO + Ag →CuO + Ag[Equation 1] CuO + Ag → CuO + Ag
만약, 코어가 금속산화물이 아닌 금속으로 이루어진 경우 바인더 번아웃단계 및 소결단계를 거치면서 산화분위기 하에서 열처리가 이루어지게 되면 코어인 금속의 일부가 산화가 일어날 수 있는데, 코어가 금속에서 금속산화물이 되어버리면 금속이 수축하거나 팽창하여 전극이 깨지거나 휘어지는 문제점이 발생한다. 이런 이유로 본 발명에서는 코어로 금속이 미리 산화가 된 금속산화물을 사용하여 열처리에 의해 금속의 팽창 또는 수축이 일어나지 않도록 한 것이다.If the core is made of a metal other than a metal oxide, when the heat treatment is performed under an oxidizing atmosphere while undergoing a binder burnout step and a sintering step, a part of the core metal may be oxidized, and the core becomes a metal oxide in the metal. If thrown away, the metal shrinks or expands, causing the electrode to break or bend. For this reason, in the present invention, the metal is oxidized in advance as a core to prevent metal expansion or contraction by heat treatment.
정리하자면, 바인더 번아웃 및 소결을 위한 1차 열처리단계는 산화분위기 하에서 이루어지는데, 산화분위기는 일부 산소가 포함된 공기 분위기 또는 질소, 아르곤 등 비활성 기체와 산소가 혼합된 분위기를 의미할 수 있긴 하나, 산화분위기가 아닌 비활성기체 분위기 또는 환원분위기를 통해 세라믹적층체를 열처리할 경우 금속산화물로 이루어진 세라믹적층체가 고온에서 성질이 변할 우려가 있기 때문에 세라믹적층체의 열처리는 산화분위기 하에서 이루어지는 것이 바람직하다.In summary, the primary heat treatment step for binder burnout and sintering is performed under an oxidizing atmosphere, which may mean an air atmosphere containing some oxygen or an atmosphere in which an inert gas such as nitrogen or argon is mixed with oxygen. When heat-treating the ceramic laminate through an inert gas atmosphere or a reducing atmosphere rather than an oxidizing atmosphere, it is preferable that the heat treatment of the ceramic laminate is performed under an oxidizing atmosphere, since there is a possibility that the properties of the ceramic laminate made of metal oxide may change at high temperature.
종래의 경우에는 산화분위기 하에서 열처리가 이루어질 경우 세라믹적층체의 성질은 유지할 수 있으나 금속분말이 산화되는 문제점이 있어 일반적으로 비활성 기체 분위기 하에서 이루어지곤 했다.In the conventional case, when the heat treatment is performed under an oxidizing atmosphere, the properties of the ceramic laminate may be maintained, but there is a problem in that the metal powder is oxidized, and thus it is generally performed under an inert gas atmosphere.
하지만 본 발명의 경우에는 코어로 금속이 아닌 금속산화물을 사용하기 때문에 금속의 산화를 방지하려는 노력을 하지 않아도 된다. 여기서 산화분위기에서 비활성기체는 0.1~99부피%로 혼합되고, 산소는 1~99.9부피% 혼합된 분위기일 수 있다.However, in the case of the present invention, since a metal oxide is used as the core, not an effort to prevent oxidation of the metal. Here, in the oxidizing atmosphere, the inert gas may be mixed in an amount of 0.1 to 99% by volume, and oxygen may be in an atmosphere of 1 to 99.9% by volume.
마지막으로, 2차 열처리단계는 1차 열처리된 세라믹적층체를 환원분위기 하에서 2차 열처리하여 금속산화물이 금속으로 환원되면서 공극이 생성되고, 공극에 의해 환원된 금속이 나노포러스(nanoporous) 구조를 갖는 단계이다(S50).Finally, in the second heat treatment step, the first heat-treated ceramic laminate is subjected to a second heat treatment under a reducing atmosphere, whereby metal oxides are reduced to metals, and voids are generated, and the metals reduced by the pores have a nanoporous structure. It is a step (S50).
2차 열처리단계는 1차 열처리된 세라믹적층체를 수소를 포함한 환원분위기 하에서 2차 열처리하여 금속산화물에서 산소가 분리되면서 금속으로 환원되고, 산소가 분리된 부분에 공극이 생성됨으로써 환원된 금속이 나노포러스(nanoporous) 구조를 갖도록 하는 것으로, 본 발명의 특징이 되는 공정이다.In the second heat treatment step, the first heat-treated ceramic laminate is subjected to a second heat treatment under a reducing atmosphere containing hydrogen, whereby oxygen is separated from the metal oxide and reduced to metal. It is a process that is characterized by the present invention by having a porous structure.
즉 2차 열처리단계에서는 금속산화물이 전기적 특성을 띄도록 금속으로 환원시키기 위해 세라믹적층체를 도 5에 도시된 것처럼 1차 열처리보다 낮은 온도인 300~500℃ 및 수소와 질소의 혼합(N2/H2 가스)의 환원분위기 하에서 열처리한다. 단, 수소 단독의 환원분위기에서 2차 열처리할 수도 있으나, 수소 단독으로 사용하면 폭발의 위험이 있기 때문에 수소와 질소의 혼합분위기 하에서 2차 열처리가 이루어지도록 하는 것이 바람직하다.That is, in the second heat treatment step, in order to reduce the metal oxide to metal so as to exhibit electrical properties, the ceramic laminate is mixed with hydrogen and nitrogen at a temperature lower than the first heat treatment at 300 to 500 ° C and hydrogen (N 2 / H 2 gas). However, it is also possible to perform secondary heat treatment in a reducing atmosphere of hydrogen alone, but it is preferable to perform secondary heat treatment under a mixed atmosphere of hydrogen and nitrogen because there is a risk of explosion when used alone.
도 3-(c)를 참조하면, 코어로써 금속산화물의 일종인 구리산화물(CuO)이 수소와 만나 구리(Cu)로 환원되고, 수소와 산소와의 결합으로 생성된 물은 수증기가 되어 증발하게 됨으로써, CuO의 O가 있던 자리에 공극(porosity)이 생성되면서 CuO로부터 환원된 Cu 금속은 다공성 입자로 바뀌게 되어 나노포러스 구조를 가짐을 모식적으로 나타낸 것임을 알 수 있다.Referring to FIG. 3- (c), as a core, copper oxide (CuO), which is a kind of metal oxide, meets hydrogen and is reduced to copper (Cu), and water generated by the combination of hydrogen and oxygen becomes water vapor and evaporates. As a result, it can be seen that the Cu metal reduced from CuO is converted into porous particles and has a nanoporous structure as porosity is generated at the place where O of CuO was.
도 4-(c)를 참조하면, 도 3-(c)의 SEM 사진을 나타낸 것으로, 아래의 [식 2]와 같은 과정으로 CuO가 수소를 포함한 환원분위기에서 H2와 만나 Cu 금속으로 환원되고, H2와 금속산화물인 CoO로부터 분리된 O가 결합된 물(H2O)은 증발됨을 확인할 수 있다.Referring to FIG. 4- (c), the SEM photograph of FIG. 3- (c) is shown, and CuO meets H 2 in a reducing atmosphere containing hydrogen and is reduced to Cu metal in the same process as [Equation 2] below. , It can be seen that H 2 and water (H 2 O) combined with O separated from H 2 and metal oxide CoO are evaporated.
[식 2] CuO + H2 →Cu + H2O[Equation 2] CuO + H 2 → Cu + H 2 O
특히 [식 2]를 참조하면, CuO가 Cu로 환원될 때 볼륨 체인지가 생기면서 수축이 발생할 수 있는데, 이를 억제하기 위해 코어-쉘 분말 준비단계에서 쉘로 은(Ag)과 같은 금속을 첨가한 것이다. 이러한 은(Ag)의 작용으로 CuO로부터 환원된 Cu가 수축하지 않고 Cu 내에 안정적인 공극 생성으로 나노포러스 구조를 갖게 해준다.In particular, referring to [Equation 2], when CuO is reduced to Cu, a volume change occurs and shrinkage may occur. In order to suppress this, a metal such as silver (Ag) is added as a shell in the core-shell powder preparation step. . Due to the action of silver (Ag), Cu reduced from CuO does not shrink and has a nanoporous structure by generating stable voids in Cu.
상기의 도 3-(c) 및 도 4-(c)에 나타난 바와 같이, 2차 열처리단계를 통해 금속산화물의 환원이 이루어짐이 확인되며, 2차 열처리를 통하여 금속산화물이 환원되면서 산소가 있던 자리에 나노포러스 구조가 생기는 나노포러스 환원 금속을 형성하게 된다. 이와 같이 환원분위기 하에서 2차 열처리를 하여 금속산화물을 나노포러스 구조를 갖는 금속으로 회수되고, 나노포러스한 구조의 Cu/Ag 구조를 형성함을 통해 세라믹소자의 특성이 우수해진다.As shown in FIGS. 3- (c) and 4- (c) above, it is confirmed that the reduction of the metal oxide is achieved through the second heat treatment step, and the place where oxygen was generated while the metal oxide was reduced through the second heat treatment. A nanoporous reducing metal having a nanoporous structure is formed thereon. As described above, the secondary heat treatment is performed under a reducing atmosphere to recover the metal oxide as a metal having a nanoporous structure, and thereby forming a Cu / Ag structure having a nanoporous structure, thereby improving the characteristics of the ceramic device.
비활성 기체 분위기 하에서도 금속분말이 일부 산화되기 때문에 본 발명에서는 미리 산화된 금속산화물을 사용하고, 이를 환원하여 세라믹테이프의 성질을 변화시키지 않으면서 본 단계인 환원분위기 하에서 2차 열처리를 수행하여 최종적으로 특성이 매우 우수한 세라믹소자를 형성하게 되는 것이다.Since the metal powder is partially oxidized even under an inert gas atmosphere, in the present invention, a pre-oxidized metal oxide is used, and the second heat treatment is performed under a reducing atmosphere, which is the present step, without reducing the properties of the ceramic tape by reducing it. It is to form a ceramic device having very excellent properties.
2차 열처리의 경우 300~500℃에서 이루어지는 것이 바람직한데, 300℃ 미만에서도 가능할 수 있으며, 500℃를 초과할 경우에는 세라믹적층체가 수소와 반응하여 성질이 변할 수 있기 때문에 되도록 환원분위기에서는 500℃ 이하에서 열처리가 이루어져야 한다.In the case of the secondary heat treatment, it is preferable to be performed at 300 to 500 ° C. It may be possible at less than 300 ° C. If it exceeds 500 ° C, the ceramic laminate may react with hydrogen to change its properties. In the heat treatment should be done.
도 6은 본 발명의 바람직한 실시예에 따른 2차 열처리 온도에 의한 구리의 다공성 특성을 나타낸 SEM 사진이다. 도 6-(a)는 300℃에서, 도 6-(b)는 400℃에서, 도 6-(c)는 500℃에서 각각 2차 열처리한 후 구리의 SEM 사진을 나타낸 것으로, 온도가 300℃에서부터 500℃로 갈수록 공극의 크기가 커짐을 알 수 있다.6 is a SEM photograph showing the porous properties of copper by the secondary heat treatment temperature according to a preferred embodiment of the present invention. 6- (a) is 300 ° C., FIG. 6- (b) is 400 ° C., and FIG. 6- (c) is a SEM image of copper after the second heat treatment at 500 ° C., and the temperature is 300 ° C. From it can be seen that the size of the pores increases as the temperature goes to 500 ° C.
도 7은 본 발명의 바람직한 실시예에 따른 2차 열처리 온도에 의한 전기저항 변화를 나타낸 그래프이다. 도 7을 참조하면, 높은 저항을 사용하여 절연저항을 측정한 것으로 2차 열처리 온도에 따른 세라믹소자의 전기저항 변화 추이를 나타낸 것이다. 그 결과, 2차 열처리 온도 범위 내에서 세라믹의 저항은 크게 변화하지 않음을 확인할 수 있었다.7 is a graph showing a change in electrical resistance due to a secondary heat treatment temperature according to a preferred embodiment of the present invention. Referring to FIG. 7, insulation resistance is measured using a high resistance, and shows a change in electrical resistance of a ceramic device according to a secondary heat treatment temperature. As a result, it was confirmed that the resistance of the ceramic did not change significantly within the secondary heat treatment temperature range.
도 8은 본 발명의 바람직한 실시예에 따른 2차 열처리 후 전극의 전도도이다. 도 8을 참조하면, Bulk Cu, Bulk Ag, AgPd 합금 대비 본 발명의 전극(CuO가 환원된 CuAg)의 전도도를 측정한 것임을 알 수 있다. 이러한 도 8에 따르면, Bulk Cu, Bulk Ag, AgPd 합금의 전기전도성에 대비하여 본 발명의 전극의 전기전도성도 거의 유사하게 나옴을 확인할 수 있었다.8 is a conductivity diagram of an electrode after secondary heat treatment according to a preferred embodiment of the present invention. Referring to FIG. 8, it can be seen that the conductivity of the electrode (CuO with reduced CuAg) of the present invention compared to a Bulk Cu, Bulk Ag, or AgPd alloy is measured. According to FIG. 8, it was confirmed that the electrical conductivity of the electrode of the present invention is almost similar to the electrical conductivity of the Bulk Cu, Bulk Ag, and AgPd alloys.
이하, 본 발명의 금속산화물을 이용한 세라믹소자 및 이의 제조방법에 따른 실시예 및 비교예를 설명해 보고자 한다. 단, 이하의 실시예 및 비교예는 본 발명의 이해를 돕기 위하여 예시하는 것일 뿐, 이에 의하여 본 발명의 범위가 한정되는 것은 아니다.Hereinafter, examples and comparative examples according to the ceramic element using the metal oxide of the present invention and a method for manufacturing the same will be described. However, the following examples and comparative examples are only illustrative to aid understanding of the present invention, and the scope of the present invention is not limited thereby.
<실시예 1><Example 1>
먼저 은(Ag)에 대한 산화구리(CuO) 분말의 습윤성을 좋게 하기 위해 붕규산 유리 전구체를 사용했다. 졸 형태의 붕규산 유리 전구체 용액을 산화구리 분말과 혼합했고, 이어서 산화구리 용액을 6.3mL의 올레인산과 40mL의 아세톤 혼합물에 첨가했다. 혼합용액을 실온에서 90분간 교반한 다음 약 70℃에서 2시간 동안 가열하고, 아세톤을 이용하여 세척했다. 그 다음 혼합용액을 약 80℃의 오븐에서 건조시킨 후 산화구리-은으로 이루어진 코어-쉘 분말을 얻었다.First, to improve the wettability of the copper oxide (CuO) powder with respect to silver (Ag), a borosilicate glass precursor was used. The sol-form borosilicate glass precursor solution was mixed with the copper oxide powder, and then the copper oxide solution was added to a mixture of 6.3 mL oleic acid and 40 mL acetone. The mixed solution was stirred at room temperature for 90 minutes, then heated at about 70 ° C for 2 hours, and washed with acetone. Then, the mixed solution was dried in an oven at about 80 ° C. to obtain a core-shell powder composed of copper oxide-silver.
질산은(AgNO3, 0.003M)을 증류수 50mL와 혼합하고, 주사기를 사용하여 수산화암모늄(NH4OH)을 적가하였다. 이때 암모니아 1 방울을 가하여 투명한 용액이 갈색으로 변하였는데, 암모니아를 더 떨어뜨리면 투명한 용액이 된다. 이러한 용액을 50mL 증류수의 첨가로 희석시켰다. 희석된 200mL의 용액을 200mg의 산화구리 분말과 혼합한 다음 5mL의 DI water에 0.036g의 세틸트리메틸암모늄브로마이드(CTAB)가 함유된 용액에 첨가하였다. 혼합용액을 교반하고 10분간 초음파처리를 하였다. 그 다음 혼합용액을 0.18g의 포도당을 함유하는 50mL의 증류수와 혼합 및 교반하고, 30분동안 120℃까지 가열하였다. 이를 통해 코어-쉘 구조의 금속산화물로 은(Ag)이 표면에 코팅된 산화구리(CuO)를 얻었다.Silver nitrate (AgNO 3 , 0.003M) was mixed with 50 mL of distilled water, and ammonium hydroxide (NH 4 OH) was added dropwise using a syringe. At this time, 1 drop of ammonia was added to make the transparent solution turn brown. If more ammonia was added, it became a transparent solution. This solution was diluted with the addition of 50 mL distilled water. The diluted 200 mL solution was mixed with 200 mg of copper oxide powder, and then added to a solution containing 0.036 g of cetyltrimethylammonium bromide (CTAB) in 5 mL of DI water. The mixed solution was stirred and sonicated for 10 minutes. Then the mixed solution was mixed and stirred with 50 mL of distilled water containing 0.18 g of glucose, and heated to 120 ° C. for 30 minutes. As a result, copper (CuO) coated with silver (Ag) on the surface of the core-shell metal oxide was obtained.
이들 산화구리-은(CuO-Ag) 분말을 붕규산 유리 전구체의 용액과 혼합하고, 그 후 용액을 120℃에서 3시간 동안 가열하여 표면에 유리가 코팅된 CuO-Ag 분말을 형성시켰다. 이어서 CuO-Ag 분말을 유기물(Ferro Co. 75001 또는 α-terpinol)과 6:4의 분말 대 유기물 중량비로 혼합하여 전극용 페이스트를 형성하였다. 이때 CuO-Ag 분말은 평균 직경이 2㎛인 균일한 입자 분포를 가짐이 확인되었다.These copper-silver (CuO-Ag) powders were mixed with a solution of a borosilicate glass precursor, and then the solution was heated at 120 ° C. for 3 hours to form a glass-coated CuO-Ag powder. Subsequently, CuO-Ag powder was mixed with an organic material (Ferro Co. 75001 or α-terpinol) in a weight ratio of 6: 4 to form an electrode paste. At this time, it was confirmed that the CuO-Ag powder has a uniform particle distribution having an average diameter of 2 μm.
제조된 내부전극용 페이스트를 세라믹테이프의 표면에 전극이 형성될 부분에 전극패턴을 따라 도포하고, 다시 그 위에 세라믹테이프를 적층하는 과정을 반복하여 세라믹적층체를 구성하였다.A ceramic laminate was formed by repeating the process of applying the prepared internal electrode paste on the surface of the ceramic tape on the surface of the electrode to be formed along the electrode pattern, and then stacking the ceramic tape thereon.
여기서 세라믹테이프로는 (Bi0.37Na0.37Sr0.26)TiO3 (BNST)가 1%의 첨가제 CuO를 갖는 세라믹테이프를 선택하였다. BNST의 경우 전계인가에 의해 완화 기에서 강유전체 층으로의 전이를 나타내며 큰 기계 변형을 수반하는데, 이러한 BNST는 큰 변형 거동(> 0.2% 변형)을 수반하는 전계(최대 4kV/mm)의 적용으로 강유전성 마이크로 도메인에 나노 극 영역의 복귀를 보여준다. 그 다음, 필드(4kV/mm→0kV/mm)를 제거하면 완전 역전 전이가 전계 방향으로 완전히 가역적인 변형 거동을 허용하는데, 이 큰 변형은 작동 메커니즘으로 사용될 수 있다.Here, as a ceramic tape, (Bi 0.37 Na 0.37 Sr 0.26 ) TiO 3 (BNST) was selected as a ceramic tape having 1% additive CuO. In the case of BNST, it represents the transition from the relaxation group to the ferroelectric layer by applying an electric field, and it involves a large mechanical deformation, and this BNST is ferroelectric by applying an electric field (up to 4 kV / mm) with a large deformation behavior (> 0.2% strain). The micro-domain shows the return of the nanopole region. Then, by removing the field (4 kV / mm → 0 kV / mm), the full reversal transition allows a completely reversible deformation behavior in the direction of the electric field, which can be used as an actuation mechanism.
BNST에 CuO를 첨가하면 최적의 소결 조건이 1,150℃에서 950℃로 감소하는데, 이는 CuO-Ag 내부전극과 동일한 소결 조건을 위하여 첨가물로 세라믹에 필요함을 의미한다. CuO를 사용한 BNST는 950℃에서 소결 시 적절한 물리적 및 전자 기계적 성질을 나타냄에 따라 다층 세라믹소자의 세라믹 층으로 BNST와 CuO를 사용하였다.When CuO is added to BNST, the optimum sintering condition is reduced from 1,150 ° C to 950 ° C, which means that it is necessary for the ceramic as an additive for the same sintering conditions as the CuO-Ag internal electrode. BNST using CuO used BNST and CuO as a ceramic layer of a multi-layered ceramic device as it exhibited appropriate physical and electromechanical properties when sintered at 950 ° C.
유기물질을 제거하기 위해 150℃에서 2시간 동안 열처리 한 후, 450℃에서 4시간 동안 가열하고 550℃에서 6시간 동안 가열하는 열처리를 통해 바인더 번아웃을 수행하였다. 이후, 샘플은 공기 중 9℃/min의 속도로 950℃까지 가열한 다음 950℃에서 4시간 동안 유지하여 소결하였다. 후처리로써, 샘플을 H2/N2(5:95 부피비) 분위기 하에 3℃/min의 속도로 300℃까지 가열한 다음 300℃에서 6시간 동안 유지시켰다.Binder burnout was performed by heat treatment at 150 ° C. for 2 hours to remove the organic material, followed by heating at 450 ° C. for 4 hours and heating at 550 ° C. for 6 hours. Thereafter, the sample was heated to 950 ° C at a rate of 9 ° C / min in air and then sintered by holding at 950 ° C for 4 hours. As a work-up, the sample was heated to 300 ° C. at a rate of 3 ° C./min under an H 2 / N 2 (5:95 volume ratio) atmosphere and then maintained at 300 ° C. for 6 hours.
<비교예 1><Comparative Example 1>
실시예 1의 CuO-Ag/BNST와는 다른 AgPd/BNST를 준비했다.AgPd / BNST different from CuO-Ag / BNST of Example 1 was prepared.
<실험예 1><Experimental Example 1>
본 실험예 1에서는 실시예 1의 CuO-Ag/BNST와 비교예 1의 AgPd/BNST를 이용하여 세라믹소자에 대한 분극 및 변형률-전계곡선을 그래프로 측정하여 성능 비교를 하였다.In Experimental Example 1, the performance was compared by measuring the polarization and strain-electric field curves for the ceramic elements using graphs of CuO-Ag / BNST of Example 1 and AgPd / BNST of Comparative Example 1.
도 9는 세라믹소자에 대한 분극 및 변형률-전계곡선 그래프이다. 비교예 1에 따른 AgPd/BNST와 실시예 1에 따른 CuO-Ag/BNST는 도 9에서 보듯이 거의 같은 단극성 및 양극성 변형과 분극 거동을 보였다. 즉 무연 세라믹 BNST와 함께 CuO-Ag가 환원된 CuAg 전극을 사용한 결과는 적층형 세라믹소자 제조가 공기 중 동시 소성 공정으로 제작할 수 있음을 의미한다.9 is a graph of polarization and strain-field curves for a ceramic device. AgPd / BNST according to Comparative Example 1 and CuO-Ag / BNST according to Example 1 showed almost the same unipolar and bipolar strain and polarization behavior as shown in FIG. 9. That is, the result of using a CuAg electrode in which CuO-Ag is reduced along with a lead-free ceramic BNST means that the production of a multilayer ceramic element can be produced by a simultaneous firing process in air.
상술된 바에 따르면, 본 발명은 코어-쉘 분말을 사용하여 열처리 과정 중 전극이 구부러지거나 깨지거나 끊어지는 현상이 발생하지 않으며, 코어-쉘 분말을 최종적으로 환원시켜 금속산화물 중 산소가 제거되면서 산소가 있던 자리에 공극이 생성된 나노포러스 구조를 갖는 금속을 형성하게 된다. 이러한 나노포러스 구조를 갖는 금속을 전극에 적용할 경우 스트레인 특성이 좋을 뿐만 아니라 전기전도도가 증가하여 전기전도성이 우수한 적층 세라믹소자를 얻을 수 있게 되는데 의미가 있다.According to the above, the present invention does not cause a phenomenon in which the electrode is bent, cracked, or broken during the heat treatment process using the core-shell powder, and oxygen is removed while oxygen is removed from the metal oxide by finally reducing the core-shell powder. A metal having a nanoporous structure in which voids are formed will be formed at the site. When a metal having such a nanoporous structure is applied to an electrode, not only is the strain property good, but the electrical conductivity is also increased, which makes it possible to obtain a multilayer ceramic device having excellent electrical conductivity.
이상의 설명은 본 발명의 기술 사상을 예시적으로 설명한 것에 불과한 것으로, 본 발명이 속하는 기술분야에서 통상의 지식을 가진 자라면 본 발명의 본질적인 특성에서 벗어나지 않는 범위에서 다양한 수정 및 변형이 가능할 것이다.The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and variations without departing from the essential characteristics of the present invention.
따라서 본 발명에 개시된 실시예는 본 발명의 기술 사상을 한정하기 위한 것이 아니라, 설명하기 위한 것이고, 이러한 실시예에 의하여 본 발명의 기술 사상의 범위가 한정되는 것도 아니다.Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to illustrate, and the scope of the technical spirit of the present invention is not limited by these embodiments.
본 발명의 보호 범위는 특허청구범위에 의하여 해석되어야 하며, 그와 동등한 범위 내에 있는 모든 기술사상은 본 발명의 권리범위에 포함되는 것으로 해석되어야 할 것이다.The scope of protection of the present invention should be interpreted by the claims, and all technical ideas within the equivalent range should be interpreted as being included in the scope of the present invention.

Claims (5)

  1. 산화구리, 산화니켈로 이루어진 군에서 선택되는 1종 이상의 금속산화물로 이루어진 코어 및 금속으로 이루어져 상기 코어를 감싸는 쉘로 구성된 코어-쉘 분말을 형성하는 단계;Forming a core-shell powder composed of a core made of one or more metal oxides selected from the group consisting of copper oxide and nickel oxide and a shell surrounding the core;
    상기 코어-쉘 분말의 표면에 유리를 코팅한 후 바인더와의 혼합으로 페이스트를 형성하는 단계;Forming a paste by coating glass on the surface of the core-shell powder and then mixing with a binder;
    세라믹테이프에 상기 페이스트를 프린팅한 후 적층하여 세라믹적층체를 형성하는 단계;Forming the ceramic laminate by printing and laminating the paste on a ceramic tape;
    상기 세라믹적층체를 산화분위기 하에서 1차 열처리하는 단계; 및First heat-treating the ceramic laminate under an oxidizing atmosphere; And
    상기 1차 열처리된 세라믹적층체를 수소를 포함한 환원분위기 하에서 2차 열처리하여 상기 금속산화물에서 산소가 분리되면서 금속으로 환원되고, 상기 산소가 분리된 부분에 공극이 생성됨으로써 상기 환원된 금속이 나노포러스(nanoporous) 구조를 갖는 단계;를 포함하는 것을 특징으로 하는 금속산화물을 이용한 세라믹소자의 제조방법.The first heat-treated ceramic laminate is subjected to a second heat treatment under a reducing atmosphere containing hydrogen, thereby reducing oxygen to the metal as oxygen is separated from the metal oxide, and voids are formed in the portion where the oxygen is separated, so that the reduced metal is nanoporous. (Nanoporous) having a structure; Method for manufacturing a ceramic device using a metal oxide, characterized in that it comprises a.
  2. 제1항에 있어서,According to claim 1,
    상기 1차 열처리하는 단계는,The first heat treatment step,
    상기 세라믹적층체를 100~600℃에서 바인더 번아웃(binder-burn-out)을 통해 상기 바인더를 탈지시키는 단계; 및Degreasing the binder through a binder-burn-out at 100 to 600 ° C; And
    상기 바인더 번아웃된 세라믹적층체를 900~1,000℃에서 소결하는 단계;를 포함하는 것을 특징으로 하는 금속산화물을 이용한 세라믹소자의 제조방법.Method of manufacturing a ceramic device using a metal oxide comprising a; sintering the ceramic burned-out ceramic laminate at 900 ~ 1,000 ℃.
  3. 제1항에 있어서,According to claim 1,
    상기 나노포러스 구조를 갖는 단계에서는,In the step of having the nanoporous structure,
    수소와 질소의 혼합분위기 하에서 300~500℃로 2차 열처리하는 것을 특징으로 하는 금속산화물을 이용한 세라믹소자의 제조방법.Method for manufacturing a ceramic element using a metal oxide, characterized in that the secondary heat treatment to 300 ~ 500 ℃ under a mixed atmosphere of hydrogen and nitrogen.
  4. 제3항에 있어서,According to claim 3,
    상기 나노포러스 구조를 갖는 단계에서는,In the step of having the nanoporous structure,
    상기 2차 열처리의 온도가 300℃에서 500℃로 갈수록 상기 환원된 금속에 생성되는 공극의 크기가 커지는 것을 특징으로 하는 금속산화물을 이용한 세라믹소자의 제조방법.Method of manufacturing a ceramic element using a metal oxide, characterized in that the size of the pores generated in the reduced metal increases as the temperature of the second heat treatment increases from 300 ° C to 500 ° C.
  5. 세라믹테이프; 및Ceramic tape; And
    산화구리, 산화니켈로 이루어진 군에서 선택되는 1종 이상의 금속산화물로 이루어진 코어 및 금속으로 이루어져 상기 코어를 감싸는 쉘로 구성되어 표면에 유리가 코팅된 후 바인더와 혼합된 상태로 상기 세라믹테이프에 프린팅되는 전극;을 포함하여 다층구조로 적층되는 세라믹적층체이되,An electrode made of a core made of one or more metal oxides selected from the group consisting of copper oxide and nickel oxide and a shell surrounding the core, coated with glass on the surface, and then printed on the ceramic tape in a mixed state with a binder. Including; but laminated ceramic stacked in a multi-layer structure,
    상기 세라믹적층체는,The ceramic laminate,
    산화분위기 하에서 1차 열처리된 후, 환원분위기 하에서 2차 열처리될 시 상기 금속산화물에서 산소가 분리되면서 금속으로 환원되고, 상기 산소가 분리된 부분에 공극이 생성됨으로써 상기 환원된 금속이 나노포러스(nanoporous) 구조를 갖는 것을 특징으로 하는 금속산화물을 이용한 세라믹소자.After the first heat treatment under an oxidizing atmosphere, when the second heat treatment is performed under a reducing atmosphere, oxygen is separated from the metal oxide and reduced to metal, and voids are formed in the portion where the oxygen is separated, so that the reduced metal is nanoporous. ) Ceramic element using a metal oxide, characterized in that it has a structure.
PCT/KR2019/011055 2018-09-19 2019-08-29 Ceramic element using metal oxide and method for manufacturing same WO2020060062A1 (en)

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KR101266002B1 (en) * 2012-10-12 2013-05-22 김형태 Fabrication method of multi-layer ceramics capacitor using dry process
KR101509878B1 (en) * 2013-01-31 2015-04-07 건국대학교 산학협력단 Metal­ceramic core­shell structured composite powder for multi­layered ceramic capacitor prepared by gas phase process and the preparation method thereof

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JP2004289089A (en) * 2003-03-25 2004-10-14 Murata Mfg Co Ltd Method of manufacturing multilayer ceramic electronic component
US20080010796A1 (en) * 2004-11-24 2008-01-17 Ning Pan High power density supercapacitors with carbon nanotube electrodes
KR101018240B1 (en) * 2008-08-12 2011-03-03 삼성전기주식회사 Multi-layered ceramic capacitor and manufacturing method of the same
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