• Resources Recycling
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• v.31 no.6
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• pp.52-59
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• 2022

Calcium silicate based cement (CSC) is a low-carbon cement that emits less CO₂ by up to 70% compared to ordinary Portland cement during its manufacture. Most developed countries have commercialized CSC, whereas Korea is still investigating the manufacturing characteristics and basic properties of CSC. This paper provides a review of methods for manufacturing CSC using domestic raw materials and discusses the possibility of CSC localization based on an evaluation of the basic physical properties of manufactured CSC. The experimental results of this study indicate that the primary mineral components of CSC were CS, C₃S₂ C₂S, and unreacted SiO₂. This suggests the possibility of manufacturing CSC using domestic raw materials that exhibit mineral compositions similar to that of theoretical CSC. The compressive strength of CSC mortar is less than 1MPa at the age of 7 d under wet curing. This implies that hydration does not affect the property development of CSC mortar. Meanwhile, during carbonation curing, the compressive strength is 56 MPa or higher after 7 d, which indicates excellent early strength development. Furthermore, results of Thermogravimetric Analysis Differential scanning calorimetry (TG/DSC) show that a significant amount of CaCO₃ is formed, which is consistent with the results of previous studies. This implies that carbonation is associated significantly with the properties of CSC.

• Journal of the Mineralogical Society of Korea
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• v.21 no.1
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• pp.27-35
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• 2008

Characterization of mineralogy and nanocrystals of ingredient materials of $Lumilite^{(R)}$ used for water treatment was made using optical microscopy, XRD, SEM, FTIR, and XRF analyses. Constituent minerals identified by XRD and microscope are clinoptilolite, illite, quartz, and albite, characterized by dense and fine texture. The cross section of nanocrystals with the size $70{$\sim}100\;nm$ is generally round or subround. Numerous spheroids with few nanometers in diameter are extensively formed on the surface of nanocrystals. Bulk chemistry is $SiO_2$ $74.22{\sim}75.65\;wt.%$, $Al_2O_3$ $13.25{\sim}13.72\;wt.%$, CaO $4.23{\sim}5.15\;wt.%$, with other major elements being minimal. When heated to $700^{\circ}C$, the crystal structure was mostly destroyed, though it persisted to $500^{\circ}C$. It is likely that high capacity and applications of $Lumilite^{(R)}$ for water treatment are originated from its structural properties such as development of nanocrystals and various tiny pores.

• Economic and Environmental Geology
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• v.55 no.5
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• pp.447-463
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• 2022

The lime and clay that used in the construction of the Tomb of King Muryeong and the Royal Tombs in Gongju are auxiliary materials, and are used joint and plaster materials for the wall to play a role of structural support. In this study, the homogeneity between the tombs and material characteristics were interpreted through quantitative analysis of lime and clay. As a result of microtexture and composition analysis, almost the same minerals were identified in each sample groups, and similar characteristics were shown in thermal analysis. Geochemically, it is confirmed that the behavior characteristics are very similar regardless of the tombs. The compositions is also confirmed high homogeneity in the diagrams of CaO-MgO-SiO₂, RO₂-(RO+R₂O) correlations, A-CN-K and A-CNK-FM triangles. Therefore, it is interpreted that the clay used for the construction of the tomb complex was supplied from around area, and the raw materials of lime were produced using shell fragments of oyster family based on mainly composed of calcite. It is interpreted that the raw materials of lime were supplied from middens along the west coast of down the Geumgang river in Korean peninsula, but the consideration of the supply site, needs to be cross-validated through stable isotope analysis, use of carbonate rock and reproduction experiments.

• Journal of the Korean Chemical Society
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• v.51 no.2
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• pp.178-185
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• 2007

Intermediate pentasil borosilicate zeolite-like materials have been crystallized by a novel method named steam-assisted conversion, which involves vapor-phase transport of water. Indeed, amorphous powders obtained by drying Na2O.SiO2.B2O3.TBA2O gels of various compositions using different boron sources are transformed into crystalline borosilicate zeolite belonging to pentasil family structure by contact with vapors of water under hydrothermal conditions. Using a variant of this method, a new material which has an intermediate structure of MFI/MEL in the ratio 90:10 was crystallized. The results show that steam and sufficiently high pH in the reacting hydrous solid are necessary for the crystallization to proceed. Characterization of the products shows some specific structural aspects which may have its unique catalytic properties. X-ray diffraction patterns of these microporous crystalline borosilicates are subjected to investigation, then, it is shown that the product structure has good crystallinity and is interpreted in terms of regular stacking of pentasil layers correlated by inversion centers (MFI structure) but interrupted by faults consisting of mirror-related layers (MEL structure). The products are also characterized by nitrogen adsorption at 77 K that shows higher microporous volume (0.160 cc/g) than that of pure MFI phase (0.119 cc/g). The obtained materials revealed high surface area (~600 m2/g). The infrared spectrum reveals the presence of an absorption band at 900.75 cm-1 indicating the incorporation of boron in tetrahedral sites in the silicate matrix of the crystalline phase.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.180-188
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• 2020

To replace Japanese coal ash used in the domestic cement production and to recycle large quantities of domestic pond ash, it is essential to develop the technologies for quality control of cement by using the domestic pond ash. Thus, in this study, the feasibility of using the pond ash as a raw material for cement was investigated through chemical composition and microstructure analysis. As a result, most of the domestic pond ash contained slightly more Fe2O3, chloride, and unburned carbon contents than Japanese coal ash. In particular, the contents of chloride were considerably low in the pond ash that was transferred to fresh water or collected from surface of landfill area. However, since circulating fluidized bed boiler coal ash had relatively high SO3 contents causing durability problems of cement, it was not suitable for use as a raw material for cement. Thus, to replace Japanese coal ash with the domestic pond ash, it is necessary to introduce the adjustment of mixture proportion of cement raw materials and the process of removing chloride in the pond ash.

• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.804-810
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• 2003

The fine powder produced by heating and grinding of the waste concrete in the waste construction was investigated whether utilize as substitution raw material of SiO$_2$, CaO, and Al$_2$O$_3$ source for OPC clinker manufacture is possible or not. In order to synthesize OPC clinker, limestone, shale, converter slag and fly ash were used as main raw materials, and modulus was fixed LSF 91.0, SM 2.60, IM 1.60. The synthesized clinkers were characterized. The Main products of synthesized clinker were C$_3$S, ${\beta}$-C$_2$S, C$_3$A, C$_4$AF as OPC clinker at 1,43$^{\circ}C$. As a result of TG-DTA and burnability index(B.U) analysis of each raw mixtures, the formation temperature of clinker phases was similar and B.I was showed easy burning as 48.6∼51.4.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.6
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• pp.240-246
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• 2021

In the ceramic industry, a drastic decrease in crystalline formation was found even among the glazes well known for their high crystalline productivity when the ceramic glaze was stored in wet conditions over a period. This study aimed to investigate the reason for decreasing willemite crystals during storage. As the starting materials ZnO, calcined ZnO and frit 3110 are selected; the composition for zinc crystalline glazes was set through a three-component system with the materials. The firing condition was used from previous studies. The study was observed how wet conditions affected the crystallization of zinc crystalline glazes from a day to 24 weeks. The results were obtained by particle size analysis, XRD, Raman spectroscopy and SEM analysis. The results indicated that ZnO is advantageous in terms of willemite crystalline development and growth; however, Zn(OH)₂ cluster, formed by the reaction with water during the storage, caused the decrease in ZnO level in the glaze. The reduction of ZnO in the glaze eventually interfered the willemite development and growth.

• Korean Journal of Materials Research
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• v.7 no.9
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• pp.811-823
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• 1997

차세대 반도체 배선분야에서, Cu박막은 현재의 AI을 대체할 물질로서 대두되고 있으며 CVD에 의한 선택적 증착은 Cu의 patterning과 관련하여 상당한 관심을 일으키고 있다. 본 연구에서는 (hfac)Cu(VTMS)의 유기원료를 사용하여, CVD공정변수, 운반기체, 표면 처리 공정에 따른 SiO$_{2}$, TiN, AI기판에 대한 선택성을조사하였다. 선택성은 저온(15$0^{\circ}C$), 저합(0.3Torr)에서 향상될 수 있었으며, 특히, HMDS in-situ-predosing공정에 의해 더욱 향상될 수 있었다. 모든 경우에 대해, H$_{2}$운반기체가 Ar 보다 짧은 incubation time과 높은 증착 속도가 얻어졌으며, Cu입자들의 크기가 작고 연결상태가 보다 양호하였다. 이는 H$_{2}$경우에 기판표면에 원료가 흡착되어 핵을 형성시키는 위치 (-OH)가 보다 많이 제공되기 때문으로 여겨진다. 이러한 미세구조의 차이는 H$_{2}$경우에 보다 낮은 비저항을 얻게 했다. HMDS in-situ predosing공정에 의한 Cu박막내 불순물 차이는 없었으며 뚜렷한 비저항의 차이도 나타나지 않았다.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.901-906
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• 1997

Ultrafine silicon dioxide($SiO_2$) powder was prepared from tetraethylorthosilicate(TEOS) by the gas-phase reaction. The effects of reaction temperature, flow rate of gas, TEOS concentration, and preheating temperature of reactants on the particle size were investigated. As the reaction temperature increased, average particle size of the silicone dioxide powder became smaller. Smaller particles were also obtained with decreasing the residence time of reactants in the reaction zone. Larger particles having narrow size distribution were produced with the high concentrations of the reactants. The effect of the preheating temperature was not considerable on the average particle size. The range of average particle size was from 30 nm to 58 nm depending on experimental conditions.

• Journal of Conservation Science
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• v.26 no.2
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• pp.157-169
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• 2010

This study focused on the material characteristics and archaeometric relationship between the molten glass and bronze materials within the crucibles and gilt-bronze Bodhisattva statue excavated from the Ssangbukri site in Buyeo, Korea. Yellowish green to red brown vitreous material in the crucibles was identified as lead glass which contained scarce amount of BaO, and low $Al_2O_3$ and CaO. Metallic molten material was identified as bronze of copper-tin-lead alloy with low amount of impurities that indicated well-refined materials. Also, cassiterite was used for raw metal ore of tin. The Bodhisattva statue consisted of major copper with trace impurities in the core metal, and gold amalgam in the gilded layer. Though lead isotopic analysis showed contradictory results in each lead glass, bronze and Bodhisattva statue that required further examination, it could be stated that the statue was made in the Ssangbukri site based on the high-level technical skills of bronze production.