• 한국세라믹학회지
• /
• 제20권3호
• /
• pp.243-249
• /
• 1983

This study has examined on the effect for the fitting in porcelain body of MgO-SiO system. The mixture was made of correponding in the theoretical composition of enstatite with Kyul Sung Talc and sea water magnesia cake. Hyup Jin Kaolin as clay minerals to give the mixture plasticity was added 10% by weight of the mixture. Feldspar was added inv various kinds of 1%-20% by weight of the above mixture. After the physical properties and microstructures were carefully examined the following results were obtained. 1. The addition amount of feldspar should generally be from 5% to 10% by weight of the mixture to be good for the properties of the strength and the range of the firing temperature. 2. The 5% addition amount of feldspar was good for the apparent bulk density. 3. 5% and 10% additions showed up stably excellant with respect to the various properties Therefore when we considered the apparent bulk density and the thermal shock resistance 5% addition amount of feldspar showed the most excellant properties between $1350^{\circ}C$ and $1400^{\circ}C$.

• 한국세라믹학회지
• /
• 제36권11호
• /
• pp.1243-1251
• /
• 1999

Densification behavior and microstructural evolution during the liquid-phase sintering of alumina-anorhite system were investigated as a function of MgO addition. When MgO component was added in either alumina or anorthite glass powder the aspect ratio of alumina grains decreased and concurrently the are of flat interface which was formed as a result of contact solid alumina gains rather increased. Consequently addition of MgO component in the Al2O3-amorthite system brought about suppression of the rearrangement of solid grains during the liquid phase sintering and then densification of specimens was also retarded.

• 한국세라믹학회지
• /
• 제32권11호
• /
• pp.1255-1261
• /
• 1995

Mullite-spinel-zirconia composites were prepared by reaction sintering of calcined alumina and magnesia, and zircon powders. The influence of calcining temperature on densification processes and on mechaical properties of subsequently sintered compacts was investigated. The mullite was formed by the reaction of $\alpha$-Al2O3 and amorphous SiO2 at firing temperatures over 141$0^{\circ}C$. The mullitization proceeded more rapidly in the specimen calcined at 110$0^{\circ}C$ than at either 120$0^{\circ}C$ or 130$0^{\circ}C$. Microstructures before and after the mullitization (or mullite dissociation) showed different morphologies, and their effects on mechanical properties were significant. The flexural strength and fracture toughness of the specimen calcined at 130$0^{\circ}C$ and subsequently fired at 145$0^{\circ}C$ were 316 MPa and 4.2Mpa.m1/2, respectively.

• 태양에너지
• /
• 제6권1호
• /
• pp.3-11
• /
• 1986

Minimum fludizing velocities and voidages were investigated for closely sized sand and magnesia particles with mean diameters in the range of $297-841\;{\mu}m$ over the temperature between 15 and $1.000^{\circ}C$. Boundaries between changing behaviour at $Re_{mf}=14$ and Ar=17,000 were observed. In beds of fine particles in Geldart's group "B", the minimum fluidizing velocity ($U_{mf}$) decreased as temperature increased, but not as much as expected on account of the gas viscosity increase, furthermore the increase in the minimum fluidizing voidage (${\in}_{mf}$). With larger particles in group "D", $U_{mf}$ increased, first, with temperature increase because of reduced gas density, and depending on the particle size, $U_{mf}$ reduced as flow conditions moved from turbulent to laminar. Among the correlations predicting $U_{mf}$, Ergun equation agreed best with the experimental data providing that the change in ${\in}_{mf}$ according to temperature is allowed for.

• 대한화학회지
• /
• 제8권1호
• /
• pp.5-8
• /
• 1964

In order to investigate the availability of serpentines occurring in Korea as fertilizer, the dissolving rates of Magnesia and Silicate contents in 0.5N HCl solution after heat treatment of the serpentines, have been studied. It was found that calcination of the serpentines at $700^{\circC$ for 30 min. was the best condition for utilization of serpentines as fertilizer. The weight decrease on calcining has also been discussed from the chemical point of view.

• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
• /
• pp.1009-1010
• /
• 2006

In this study, we attempt to synthesize the cordierite from the reaction of fly-ash, alumina, silicon dioxide, and magnesia powders. For the purpose of air purification, the honeycomb filter with porous cordierite was fabricated from the combination of synthetic cordierite and pore forming agent. Fabricated porous cordierite honeycomb was prepared with high porosity (58%), and good compressive strength (69MPa).

• The Korean Journal of Ceramics
• /
• 제1권4호
• /
• pp.214-218
• /
• 1995

Partially stabilized zironia with magnesia (Mg-PSZ) is known as one of the toughest monolithic ceramics. However, the very large grain sizes obtained after sintering at a high solution-heat treatment temperature in the cubic region of the phase diagram limit the strength of this material rather modest. In this study fine-grained Mg-PSZ materials were fabricated by adding TiC particles as a dispersed phase. Samples were hot-pressed at $1750^{\circ}C$ and then annealed at $1420^{\circ}C$ for various times. Grain growth was retarded severely by the TiC particles resulting in grain sizes smaller by more than one order of magnitude than those of PSZ without TiC. The fine-grained microstructure lead to doubly-increased fracture strength while maintaining the same level of high fracture toughness as that of conventional Mg-PSZ without TiC particles.

• 대한치과의사협회지
• /
• 제27권1호통권236호
• /
• pp.15-18
• /
• 1989

"62번 보다는 좀 어둡게" 또는 "62번과 65번 사이 정도로"라는 이러한 지시들이 만족스러운 결과를 가져오는가? "선생님, 제 앞니가 이젠 너무 희고 자연스럽지 않아요. 남들이 보면 해 넣은건지 금방 알아요." Porcelain fused to metal crown은 그 심미적 장점 때문에 전치부 수복에 있어 사용이 보편화되어 왔다. 하지만 두께의 제한과 세련되지 못한 일률적인 수복물은 일반적으로 너무 밝고 흰(높은 명도와 낮은 채도) 까닭에 인공적인 것을 쉽게 식별할 수 있으며, 환자들도 하여금 보다 개성화가 요구되어 오고 있다. 이러한 심미적 요구와 함께 최근 우수한 심미성과 높은 강도의 도재전장관들, 즉 Dircor이나 Cera Pearl, Alumina 또는 Magnesia core porcelain등이 연구 개발되어 왔다. 도재 축성술에 있어서도 내장된 첨색효과(internal characterization)나 다층축성법(layer build up)등 많은 방법들이 발전되어 왔다. 자연스러운 도재관을 재현하여 주기 위해서는 먼저 자연치아의 색조에 관한 치과의사의 충분한 인식과 판단이 앞서야 한다. 인식된 색조에 대한 정보가 체계적으로 기록되어 기공사에게 전달되고 재현되어야 한다.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2018년도 추계 학술논문 발표대회
• /
• pp.48-49
• /
• 2018

Recently the old buildings have been increasing and increasing reconstruction. As a result, the frequency of use of architectural adhesives has increased. Adhesives are not only used for bonding but also for building materials used in various fields. However, since the adhesive is made of an organic material, it causes various skin diseases and sick house syndrome, and when a fire occurs, harmful substances are generated, and incomplete combustion may cause personal injury. Therefore, in this study, to solve the disadvantages of conventional adhesives, we tried to develop inorganic adhesives using inorganic materials.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2018년도 추계 학술논문 발표대회
• /
• pp.79-80
• /
• 2018

Recently, the interest in remodeling of new and old buildings is increasing worldwide. As a result, the frequency of use of architectural adhesives has increased. Currently, adhesives used in buildings are made of organic materials in most cases, and epoxy resin adhesives are most widely used. However, epoxy resin adhesives contain formaldehyde and VOCs in the room during construction, which can cause sick house syndrome. In case of building fire, it may cause damage due to carbon monoxide generated from organic materials. It is urgent to study the problem of epoxy fill adhesive made of such organic materials. Therefore, the purpose of this study is to investigate the effect of the adhesion of epoxy resin adhesive, which is a problem of epoxy resin adhesive, which is an existing organic adhesive by using inorganic materials such as magnesia and phosphate, And the inorganic adhesive which does not emit the release amount as an inorganic material.