KR100239217B1 - A method of producing porous alumina - Google Patents
A method of producing porous alumina Download PDFInfo
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- KR100239217B1 KR100239217B1 KR1019970035530A KR19970035530A KR100239217B1 KR 100239217 B1 KR100239217 B1 KR 100239217B1 KR 1019970035530 A KR1019970035530 A KR 1019970035530A KR 19970035530 A KR19970035530 A KR 19970035530A KR 100239217 B1 KR100239217 B1 KR 100239217B1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/42—Preparation of aluminium oxide or hydroxide from metallic aluminium, e.g. by oxidation
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- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
- B01J19/12—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electromagnetic waves
- B01J19/122—Incoherent waves
- B01J19/126—Microwaves
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/11—Powder tap density
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Abstract
본 발명은 새로운 저수축 다공성 알루미나 제조방법에 관한 것으로 제조비용이 많이 들거나 공정시간이 긴 종전의 단점을 보완한 제조방법이다. 본 발명에서는 35체적분율 알루미늄과 65체적분율 알루미나의 혼합분말 성형체를 마이크로파로 알루미늄 입자를 급속산화시켜 알루미나로 전이시킬 때 발생하는 28% 부피 팽창으로 소결시 수축율을 억제하는 동시에 소결공정도 함께 이루어져서 단시간(1시간) 내에 선수축 변화율 -4.5% 겉보기 밀도 2.88(g/cc)의 저수축 다공성 알루미나를 제조할 수 있었다. 본 발명은 복잡한 형상의 알루미나 제조나 저수축 다공성이 필요한 구조재료에 쓰일 수 있다.The present invention relates to a novel low-shrinkage porous alumina manufacturing method, which is a manufacturing method that compensates for the disadvantages of the conventional manufacturing process, which is expensive or has a long process time. In the present invention, the mixed powder compact of 35 volume fraction aluminum and 65 volume fraction alumina suppresses the shrinkage rate during sintering at the same time as the sintering process is performed with the 28% volume expansion produced by rapid oxidation of aluminum particles by microwave to transition to alumina. Within one hour, a low shrinkage porous alumina of -4.5% apparent density 2.88 (g / cc) could be produced. The present invention can be used in the production of complex alumina or structural materials requiring low shrinkage porosity.
Description
본 발명은 저수축 다공성 알루미나 제조방법에 관한 것으로, 좀 더 설명하면 세라믹 분말 성형체를 소결할 때 발생하는 10~20%의 선수축율을 억제하여 저수축다공성 알루미나를 제조하는 방법에 관한 것이다.The present invention relates to a method for producing a low shrinkage porous alumina, and more particularly, to a method for manufacturing a low shrinkage porous alumina by suppressing a 10-20% contraction ratio generated when sintering a ceramic powder compact.
종래에는 알루미나 소결시 생기는 수축율을 줄이기 위한 공정으로 고압성형법이나 반응소결 알루미나법이 연구되었는데 고압성형법은 성형공정이 복잡하고 비용이 많이 드는 단점이 있고 반응소결 알루미나법은 전체 공정시간이 상당히 긴(12시간이상) 단점이 있다.Conventionally, high pressure molding or reaction sintering alumina has been studied as a process to reduce shrinkage caused by sintering of alumina. However, high pressure molding has a disadvantage that the molding process is complicated and costly. Over time) There is a disadvantage.
본 발명은 상기와 같은 제반 문제점을 간소화 하기 위해 발명된 것으로 알루미늄과 알루미나의 혼합성형체를 마이크로파로 조사하여 산화와 소결을 급속히 진행시켜서 단시간 안에 저수축 다공성 알루미나를 제조할 수 있는 방법을 제공하는데 그 목적이 있다.The present invention was invented to simplify the above-mentioned problems, and to provide a method for producing low shrinkage porous alumina in a short time by rapidly advancing oxidation and sintering by irradiating a mixed molded product of aluminum and alumina with microwave. There is this.
제1도는 마이크로파 반응기 안의 실험장치 도면으로서 시편, 내화물, 예열재가 배치되어 있는 모습을 보여 준다.FIG. 1 is a drawing of an experimental device in a microwave reactor, showing the arrangement of specimens, refractory materials, and preheating materials.
제2도는 마이크로파로 급속 가열했을 때의 온도별 시편의 산화량과, 마이크로파 가열과 같은 가열 속도로 통상적인 로를 사용하여 시편을 가열했을 때의 산화물을 비교한 것이다. 마이크로파 가열이 높은 산화율을 보임을 알 수 있다.FIG. 2 compares the oxidation amount of the specimen for each temperature during rapid heating with microwave and the oxide when the specimen is heated using a conventional furnace at the same heating rate as microwave heating. It can be seen that microwave heating shows a high oxidation rate.
본 발명에서는 35체적분률 알루미늄과 65체적분률 알루미나를 혼합하여 성형한 후 제1도에서 보는 바와 같이 시편을 내화갑 가운데에 배치하면 내화갑 안의 실리콘카바이드(SiC)과 지르코니아가 상온에서 마이크로파를 흡수하여서 시편을 복사와 전도열로 가열하는데, 시편의 온도가 약 1200℃를 넘게 되면 시편이 마이크로파를 흡수하여 자체발열로 가열하게 된다.In the present invention, after mixing and molding 35 volume fraction aluminum and 65 volume fraction alumina, as shown in FIG. 1, when the specimen is placed in the refractory box, silicon carbide (SiC) and zirconia in the refractory bag absorb microwave at room temperature. The specimen is heated by radiation and conduction heat. When the temperature of the specimen exceeds about 1200 ° C, the specimen absorbs microwaves and heats itself by heating.
금속은 마이크로파를 흡수하지 않는 것으로 알려져 있으나 실제로는 마이크로파가 마이크로미터(㎛) 깊이로 금속 표면에 침투하여 흡수되므로 금속을 마이크로미터 크기의 분말로 만들 경우 금속분말이 마이크로파를 흡수하여 가열된다.Metals are known to not absorb microwaves, but in reality microwaves penetrate and absorb the metal surface to a depth of micrometers (µm), so when the metal is made into micrometer-sized powder, the metal powder absorbs microwaves and heats them.
마이크로파로 시편을 가열할 때 마이크로파로 인한 표면 옴(Ohmic)전류가 시편 속의 알루미늄 입자 표면에 흐름으로서 알루미늄 입자의 산화를 촉진시켰다는 것을 제2도에서 볼 수 있다. 산화된 알루미나는 28% 체적 팽창으로 시편 소결시 발생하는 수축과 서로 상쇄되어 전체 수축율을 낮추게 된다. 또 산화된 알루미나는 시편이 가열됨에 따라 원래 첨가된 알루미나와 접합을 이루며 소결이 이루어지기 때문에 산화와 소결 공정이 1시간내에 끝낼 수 있게 된다.It can be seen in FIG. 2 that when heating the specimen with microwaves, surface ohmic currents due to the microwaves promoted oxidation of the aluminum particles as it flowed to the surface of the aluminum particles in the specimen. Oxidized alumina is offset by shrinkage during sintering of the specimen with 28% volumetric expansion, resulting in lower overall shrinkage. In addition, since the oxidized alumina is sintered and bonded with the alumina originally added as the specimen is heated, the oxidation and sintering process can be completed within 1 hour.
1650℃에서 0분 소결한 시편은 선수축 변화율이 -4.5%였으며 겉보기 밀도는 2.88(g/cc)이었다.The specimens sintered at 1650 ° C for 0 min had a bow change of -4.5% and an apparent density of 2.88 g / cc.
상술한 바와 같이 본 발명은 마이크로파를 이용하여 단시간(1시간)안에 알루미늄과 알루미나 분말 혼합체를 효과적으로 산화·소결시켰으며 선수축 변화율도 -4.5% 정도로 줄일 수 있었고 공정이 단순하여서 제조비용의 절감효과를 기대할 수 있었다.As described above, the present invention effectively oxidized and sintered the aluminum and alumina powder mixture in a short time (1 hour) using microwaves, and the bow change rate could be reduced to about -4.5%, and the process was simple to reduce the manufacturing cost. I could expect.
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| Application Number | Priority Date | Filing Date | Title |
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| KR1019970035530A KR100239217B1 (en) | 1997-07-28 | 1997-07-28 | A method of producing porous alumina |
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| KR1019970035530A KR100239217B1 (en) | 1997-07-28 | 1997-07-28 | A method of producing porous alumina |
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| KR19990012197A KR19990012197A (en) | 1999-02-25 |
| KR100239217B1 true KR100239217B1 (en) | 2000-07-01 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100803049B1 (en) * | 2007-08-31 | 2008-02-22 | (주)제이피에스 마이크로텍 | Manufacture method of flake aluminum oxide using microwave |
| KR100837357B1 (en) | 2007-02-09 | 2008-06-12 | 한국과학기술연구원 | Fabrication method of alumina powders using microwave |
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1997
- 1997-07-28 KR KR1019970035530A patent/KR100239217B1/en not_active IP Right Cessation
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100837357B1 (en) | 2007-02-09 | 2008-06-12 | 한국과학기술연구원 | Fabrication method of alumina powders using microwave |
| KR100803049B1 (en) * | 2007-08-31 | 2008-02-22 | (주)제이피에스 마이크로텍 | Manufacture method of flake aluminum oxide using microwave |
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| Publication number | Publication date |
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| KR19990012197A (en) | 1999-02-25 |
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