• 한국세라믹학회지
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• 제33권1호
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• pp.110-118
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• 1996

• 한국결정성장학회지
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• 제27권1호
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• pp.47-56
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• 2017

본 연구에서는 Alumina 골재를 사용한 fly ash-blast furnace slag계 Geopolymer의 내열성 건축자재로서의 사용 가능성을 검토하기 위하여 고온조건에서의 열적 특성에 대하여 조사하였다. 모든 배합조건에서 Geopolymer 경화체의 표면 크랙은 $800^{\circ}C$까지는 관찰되지 않았으며, 이것은 열처리 전후 강도의 변화가 작은 것과 일치한다. 또한, $800^{\circ}C$까지 고로슬래그의 혼합비율이 60 wt%일 때 잔존압축강도가 가장 우수한 것으로 나타났다. Geopolymer 경화체의 주요 수화 생성물은 $20{\sim}35^{\circ}$(2theta) 범위의 비정질 halo 패턴과 원재료의 mullite($3Al_2O_3{\cdot}2SiO_2$)와 quartz($SiO_2$)가 확인되었다. 비정질 halo 패턴은 Geopolymer 축중합 반응에 의해서 생성된 aluminosilicate gel이며, $800^{\circ}C$까지는 aluminosilicate gel의 halo 패턴이 유지되고 있음을 알 수 있다. $1,000^{\circ}C$에서 aluminosilicate gel의 패턴은 사라지며 열처리온도의 증가와 함께 gehlenite, calcium silicate, calcium aluminum oxide, microcline와 같은 결정상이 관찰되었다.

• 한국세라믹학회지
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• 제32권1호
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• pp.45-50
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• 1995

In order to densify LAS(Lithuim Aluminosilicate)system compounds, we used metal alkoxides as precursors. Also Mg was added by sol-gel method using metal alkoxides to the LAS system for improving the sinterability, thermal and mechanical properties. The result was that the synthesizing temperature was lowered about 10$0^{\circ}C$, the sintering temperature was lowered by over 10$0^{\circ}C$ and MOR of samples from metal alkoxides was two times larger than that of sample form oxide.

• 대한환경공학회지
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• 제29권7호
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• pp.810-819
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• 2007

물유리와 수산화나트륨 용액을 이용하여 플라이 애쉬와 고로슬래그의 알칼리 활성에 관한 연구를 수행하였다. 플라이 애쉬/슬래그 시멘트 페이스트(FSC)의 반응생성물과 미세구조를 관찰하기 위하여 XRD, FTIR, $^{29}Si$ and $^{27}Al$ NMR, TGA and SEM 분석을 수행하였다. 무정형 상태 또는 저급 결정구조를 가진 calcium silicate hydrate와 aluminosilicate 겔이 각각 고로슬래그와 플라이 애쉬의 알칼리 활성반응에 의해 생성되었다. 실험결과, 물유리 모듈 1.0과 1.2가 플라이 애쉬와 고로슬래그의 알칼리 활성반응을 위해 적정한 것으로 나타났다. 물유리 모듈 1.0과 1.2로 알칼리 활성화된 FSC 페이스트는 플라이 애쉬와 고로슬래그의 알칼리 활성반응에 의해 생성된 겔 형태의 반응생성물과 물유리에 의한 또 다른 수화물(즉 실리카겔)에 의해 좀 더 단단하고 연속적이 모체가 형성되었음을 보여주었다.

• 한국재료학회지
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• 제21권9호
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• pp.502-508
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• 2011

The goal of the present work was to investigate the development of a geopolymeric ceramic material from a mixture of mine residue, coal fly ash, blast furnace slag, and alkali activator solution by the geopolymer technique. The results showed that the higher compressive strength of geopolymeric ceramic material increased with an increase in active filler (blast furnace slag + coal fly ash) contents and with a reduction of mine residue contents. The geopolymeric ceramic had very high early age strength. The compressive strength of the geopolymeric ceramic depended on the added active filler content. The maximum compressive strength of the geopolymeric ceramic containing 20 wt.% mine residue was 141.2 MPa. The compressive strength of geopolymeric ceramic manufactured by adding mine residue was higher than that of portland cement mortar, which is 60 MPa, when cured for 28 days. SEM observation showed the possibility of having amorphous aluminosilicate gel within geopolymeric ceramic. XRD patterns indicate that the geopolymeric ceramic was composed of amorphous aluminosilicate, calcite, quartz, and muscovite. The Korea Standard Leaching Test (KSLT) was used to determine the leaching potential of the geopolymeric ceramic. The amounts of heavy metals were noticeably reduced after the solidification of mine residue with active filler.

• 한국세라믹학회지
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• 제45권5호
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• pp.303-308
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• 2008

Mullite precursors were synthesized with aluminosilicate gels from mixture of aluminum nitrate and sodium orthosilicate by the geopolymer technique at ambient temperature. Then, the gel was heat-treated in air up to $1200^{\circ}C$ at intervals of $100^{\circ}C$. Raw and heat-treated gels were characterized by TG-DTA, XRD, FTIR, $^{29}Si$ MAS-NMR, TEM. The result to examine the crystallization of behavior though DTA, the synthesized precursors were crystallized in the temperature range from $950^{\circ}C$ to $1050^{\circ}C$. The XRD results showed that the gel compositions were begun to crystallize at various temperature. Also, it was found that the precursors of M-4 begun to crystallize at about $950^{\circ}C$. The M-4 XRD peaks were characterized better than $M-1{\sim}M-3$ at $1000^{\circ}C$. The formation temperature of mullite in this study is much lower than that of previous sol-gel methods, which crystallized at up of $1200^{\circ}C$. TEM investigations revealed that the sample with 10 nm particle size was obtained via heat-treated at $1000^{\circ}C$ for M-4.

• 공업화학
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• 제9권5호
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• pp.615-618
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• 1998

수성 교질법에 의한 제올라이트 합성 과정에서 활성탄을 부가함으로써 제올라이트 결정화 과정에 미치는 영향과 활성탄 기공 내에서의 제올라이트 결정의 담지현상을 조사하였다. A형 제올라이트를 합성하기 위한 몰 조성비로 조절된 알루미노 실리케이트 겔상에 5 wt % 정도의 활성탄을 첨가할 경우에는 그대로 A형 제올라이트가 생성되었으나 15 wt % 정도 첨가할 경우에는 대부분이 X형이고 일부 A형과 P형 제올라이트가 혼재된 상태로 결정화가 일어났으며, 20 wt %이상 첨가할 경우에는 순수한 X형 제올라이트가 생성되었다. 활성탄의 기공 입구와 내부에는 $1{\mu}m$ 이하의 미세한 제올라이트 결정들이 서로 엉겨붙어 있는 형태로 관찰되었으며, 기공분포 및 입도분포 결과로부터 단순히 제올라이트와 활성탄의 혼합물 형태가 아니라 활성탄 기공 내에 미세한 제올라이트 결정들이 담지되어 있는 복합 소재임을 확인하였다.

• 한국세라믹학회지
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• 제32권1호
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• pp.63-70
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• 1995

A crack-free ceramic composite membrane with micropores has been synthesized by the pressurized sol-gel coating technique using the mixed Al2O3-SiO2 sols. The mixed sols were prepared by mixing nanoparticulate SiO2 and boehmite sols. These sols were more stable at lower pH, but very unstable when their copositions were in the range of 50~75mol% of SiO2 at the same pH. The mixed Al2O3-SiO2 membrane prepared from the mixed sol (0.2mol/$\ell$ of solid content and pH=2) containing 40mol% of SiO2 had the mean pore radius of 0.80nm and the specific surface area of 280$m^2$/g. The nitrogen permeability through the coated Al2O3-SiO2 layer was 42$\times$107mol/$m^2$.s.Pa. It was found that the thermal stability of aluminosilicate membranes, even through similar to that of SiO2 membranes, was much improved in comparison with ${\gamma}$-alumina membranes.

• 한국세라믹학회지
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• 제28권5호
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• pp.365-372
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• 1991

LAS (lithium aluminosilicate) sol was synthesized using the hydrolysis-condensation reaction of TEOS, chelated Al(OBus)3 and Li-salt with H2O in alcohol (EtOH+2-Propanol) medium. Effects of important reaction parameters on the properties of sol and gel-derived LAS were examined. The crystallization of the sol-gel derived LAS with ${\beta}$-spodumene composition began at ∼600$^{\circ}C$, and a series of polymorphic transformations occurred as temperature was increased to 1100$^{\circ}C$: amorphous LAS\longrightarrowhexagonal LiAl(SiO3)2\longrightarrow${\beta}$-spodumene. Lowering Li content in the gel enhanced densification and retarded the crystallization significantly. Optimum reaction conditions of LAS sol formation for thin coating applications were derived from rheological measurements, and these can be summarized as: H2O/total alkoxides molar ratio=4, pH=∼2.5, and aging time of ∼250h.

• 한국세라믹학회지
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• 제27권8호
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• pp.1011-1019
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• 1990

Pyrophyllite, which has low impurities, was used in the synthesis of mullite to decrease the glass phase, which can be formed from impurities such as alkali and alkali earth elemetns present in raw materials. But, as pyrophyllite has less alumina content than other aluminosilicate materials such as kaolin, more alumina sources were needed in the synthesis of mullite. In other to investigate the effect of particle size of alumina sources on the mullitization of pyrophyllite, aluminum hydrate gel and activated alumina were used. When activated alumina, which has large particle size, was added to pyrophyllite, mullitization was not fully accomplished regardless of temprature. In the case of aluminum hydrate gel, which has small particle size, the maximum yield of mullite was about 90.3% at 1700$^{\circ}C$, and grain size of mullite was larter than the case of activated alumina was added.